FIBIC FuBio Cellulose programme report

The FuBio Cellulose programme focuses on promoting selected novel

value chains starting from wood derived cellulose. The specific target of

the programme is to develop novel sustainable processes for production

of staple fibres, new cellulose based materials and water treatment

chemicals. The programme provides knowledge and capabilities

supporting the new value chains based on wood cellulose products.

www.fibic.fi

13Ohjelmatunnukset

Future BiorefineriesProducts from Dissolved Cellulose

Programme Report 2011-2014

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13Ohjelmatunnukset

Future Biorefinery Cellulose


Copyright Finnish Bioeconomy Cluster FIBIC 2013. All rights reserved.

This publication includes materials protected under copyright law, the copyright for which is held by

FIBIC or a third party. The materials appearing in publications may not be used for commercial pur-

poses. The contents of publications are the opinion of the writers and do not represent the official

position of FIBIC. FIBIC bears no responsibility for any possible damages arising from their use.

The original source must be mentioned when quoting from the materials.

ISBN 978-952-67969-4-9 (paperback)

ISBN 978-952-67969-5-6 (PDF)

Layout: Brand United Ltd

Printing: Kirjapaino Lönnberg

Scarf photo (cover) by: Mikko Raskinen

CONTENT

Foreword ..........................................................................................................................................................5

Promising results in creating new cellulose-based products in novel value chains ...........6

Introduction ................................................................................................................................................... 8

Ionic liquid based dissolution and regeneration processes ....................................................... 12

Water based dissolution and regeneration processes ................................................................40

Textile value chain and recommendations for future research priorities

related to FuBio Cellulose textile fibres ............................................................................................60

New cellulose products ........................................................................................................................... 72

Cationic cellulose based chemicals .................................................................................................. 102

FOREWORD

The Finnish forest industry is undergoing active renewal. This is being pursued partly due to changes in the traditional business environment, but also as a response to the opportunities presented by the emerging global bioeconomy. New wood-based products and related new and previously less known value chains are under scrutiny. Alongside paper, board and tissue, which remain the backbone of the pulp industry, the value and versatility of wood as a raw material is being intensively explored to its fullest potential, with a key focus on wood as a viable renewable alternative to petroleum-based resources.

The five-year research programme Future Biorefinery (FuBio) was launched in 2009 by the Finnish Bioeconomy Cluster FIBIC (formerly Forestcluster Ltd.). During the first phase of FuBio, several new pathways for wood-based bio-products were studied and pre-evaluated. This laid the ground for the next phase of the programme, which was dedicated to exploiting the most promising results of phase one in order to create new value chains and future business opportunities for the participating companies.

In this second phase, launched 2011, FuBio was split into two separate programmes, FuBio Joint Research 2, focusing on bioeconomy research, and the present programme FuBio Products from Dissolved Cellulose. During the programme planning stage, commercial interest towards man-made cellulosic fibres grew to new heights with the price of dissolving pulp peaking in early 2011. This market pull had a clear impact on the planning process. In addition, the first phase of FuBio had introduced some interesting processing alternatives for dissolving and regenerating cellulosic fibres and other shaped particles. These new technologies formed the basis of the new programme. FuBio Products from Dissolved Cellulose focused on developing new processes for dissolving and regenerating cellulose. The aim was twofold: to produce new fibres for use in textiles and nonwoven products, and to produce new cellulose-based materials – such as thermoformable cellulose and cationic cellulose derivatives – for use in water treatment. Understanding the business environment and cost structures as well as value chain formation and value generation were identified as critical, and these aspects were thus built in as a separate, generic work package. Considerable effort was focused on techno-economical modelling and business area and value chain analysis. It was of primary importance for the programme to include as programme partners companies active downstream in the studied value chains – i.e. potential new customers for pulp manufacturing companies. Another objective of the programme was to introduce demonstration products or materials in order to generate interest among potential future customers. This was largely successful, and also public interest was raised through the demo products.

FuBio Products from Dissolved Cellulose achieved the majority of its set targets and succeeded in bringing Finland’s forest industry an important step closer to its ultimate goal of renewal. The success stories highlighted in this report are a true embodiment of this achievement.

Kari KovasinMetsä Fibre, Industrial Coordinator of Programme

FUBIO CELLULOSE PROGRAMME REPORT6

New value chains will have a major impact on the renewal of the Finnish forest industry. Research performed in FIBIC programmes has already shown the power of novel value chains in creating new processes and products based on new raw materials.

The FuBio Cellulose programme (FuBio Products from Dissolved Cellulose) has been the first programme in the FIBIC framework to be focused on a value chain. This approach to a platform for promoting value creation in the Finnish forest industry of the future has proved to be a good choice. At the same time the programme has been able to improve general awareness of new wood-based biorefinery opportunities among the industrial companies of the sector.

The specific target of the programme was to develop novel sustainable processes for production of staple fibres, new cellulose-based materials and water treatment chemicals.

The industrial partners of the programme believe that the targets have been met very well, although the original ambition level was high, as it has to be in this kind of research.

The partners represented a broad selection of forest cluster companies. In the following chapters the companies highlight the business relevance of the results achieved in the programme.

A breakthrough in ionic liquids

A clear breakthrough in the FuBio Cellulose programme was made in research into ionic liquids used in the production of textile fibres. This work has achieved its targets and generated very valuable results.

Ionic liquids have been a key area in the programme. A team of researchers from the University of Helsinki and Aalto University has been developing new ionic liquids systems that have high potential in industrial applications.

They have even been able to spin regenerated fibres produced from ionic liquids. This work was highlighted when a dress knitted from birch cellulose fibre was displayed at a Marimekko fashion show in the spring of 2014.

The combined efforts of the University of Helsinki and Aalto University have contributed to the formation of ionic liquids competence on which the future application-oriented research can be built.

PROMISING RESULTSIN CREATING NEW CELLULOSE-BASED PRODUCTS

IN NOVEL VALUE CHAINS

Kari Kovasin, Metsä Fibre:

“The industrial concepts of ionic liquids will

require further development, but the roadmap

has been clearly defined by the results achieved

in the FuBio Cellulose programme.”

Jari Räsänen, Stora Enso:

“Fibre processing by using ionic liquids is very

high on our research agenda for the future.”

Margareta Hulden, Suominen Nonwovens:

“The results in the ionic liquids research indicate

many new product opportunities for wood-based

pulp as a feedstock. As our company makes

nonwovens, we would be a downstream user of the

potential new products, but we feel that it is always

beneficial to be involved at an early stage in the

development of raw materials that we can utilize.”

FUBIO CELLULOSE PROGRAMME REPORT 7

Feasibility studies proved to be of great importance

Several industrial participants have expressed appreciation for the techno-economic feasibility analyses of selected value chains and novel cellulose-based processes performed in the FuBio Cellulose programme.

Without understanding the characteristics of new value chains that may provide companies in the pulp and paper industry with new businesses, it is extremely difficult to develop the concepts required and to steer the research in the correct direction.

Moreover, by considering the techno-economic aspect at an early stage of the project, the management group and project teams were aided in the prioritisation and selection of development paths.

A good basis for further development

The programme and its results have been very innovative and future-oriented. And it has given a proof of concept for the high-value precommercial research in forest-based sector in Finland.

The joint research teams and knowhow platform created by the programme will make it easy to continue the work. Many companies already have plans for how they will use some of the results in the company-specified future development projects.

The participants agree that the results point in the right direction, but more work is needed before business potential can be determined.

A good example of common interest for the combined research efforts and cooperation is the new Advanced Cellulose for Novel Products (ACel) programme that FIBIC launched in the summer of 2014.

Esa Hassinen, UPM-Kymmene:

“Upgrading wood-based cellulose to higher-value

products fits well with our strategic targets.

Broadening the use of wood and fibres, and using

biomaterials for new and existing applications,

are good candidates for future businesses.”

Kari Saari, Kemira:

“The knowledge created in activation and

modification of cellulose can be utilized broadly

in future programmes. Kemira will continue to

study production and utilization of cellulose-

based products in different applications. We

expect good ongoing collaboration with the

competent partners we have had in the FuBio

Cellulose programme.”Advances in several areas

Great advances were made in several research areas of the FuBio Cellulose programme. For example, it developed and demonstrated a new cellulose dissolving-regeneration process with high sustainability and quality features, which is seen as a promising new alternative.

Non-fibre products, such as absorbent materials, have also been regenerated. They will be suitable for a great variety of end-products in the future.

Another major focus was to develop water-soluble cellulosic products to be used in various water treatment or paper manufacturing processes. They are good bio-based candidates for the future processes.


INTRODUCTION

Background

Future Biorefinery (FuBio) has been a strategic focus area of the Finnish Bioeconomy Cluster (FIBIC) during 2009-2014. The overall objective of FuBio research and development was to establish in Finland globally-competitive knowledge platforms for the renewal of existing forest industry and the creation of new business. The focus has been on creating new value chains in which biomass-based materials and chemicals are applied in substantial global markets. The potential markets of focus are both well-known to the forest industry (e.g. fibre-based packaging) as well as essentially new (e.g. textiles, nonwovens, polymers, resins and thermoformable composites). The creation of new biorefinery value chains requires deep understanding of the biomass structure. In addition, new processing technologies must be developed hand in hand with new biorefinery concepts and their related value chains. Understanding of the markets and freedom-to-operate are also needed, and the first steps towards future industrial partnerships must be taken.

The first, two-year Future Biorefinery programme (FuBio Joint Research 1) was completed in May 2011. This research was thereafter continued through two separate programmes, FuBio Joint Research 2 (FuBio JR2) and FuBio Products from Dissolved Cellulose (FuBio Cellulose). FuBio Cellulose, the focus of this report, was a value chain oriented programme building on the knowledge generated in FuBio Joint Research 1 on novel cellulose solvents and the modification of dissolved cellulose to produce bio-based materials and chemicals.

The motivation for the FuBio Cellulose value chain programme stemmed from the needs of the radically evolving forest industry. Upgrading of wood cellulose to higher value products fits the

strategic targets of generating new end uses for wood and fibre and using biomaterials in new and existing applications. In Finland, industrial interest and activity towards novel, wood cellulose-based regenerated fibre products are on the rise. This is due mainly to promising market trends, especially in textile fibres, combined with environmental considerations related to the current dominant raw material, cotton. In addition to fibre, other products such as films, beads and other cellulosic particles can also be regenerated, opening opportunities for a wide range of end products. Furthermore, targeted functionalization or manipulation of the cellulose chain paves the way towards generation of water soluble cellulosic products for use in water treatment and paper manufacture, as well as an exciting new target area – thermoplastic cellulose.

FuBio Cellulose focused on the development and evaluation of novel sustainable processing concepts for selected cellulose products. The programme aimed to promote the development of the basic knowledge and techniques of sustainable wood cellulose dissolution, regeneration and functionalisation developed in FuBio 1 towards process concepts suitable for industrial feasibility evaluation through cellulose-focused and process- and product-oriented high-quality research.

The three-year FuBio Cellulose research programme had total budget of 11.6 million euros. The Finnish Funding Agency for Innovation (Tekes) provided 60% of the financing, with the remainder sourced from the participating companies and research institutes.


Programme goals and structure

The main goal of FuBio Cellulose was to develop novel sustainable processes for the production of i) regenerated cellulose staple fibres, ii) novel functional materials based on cellulose beads, nonwovens or thermoformable structural materials, and iii) cationic cellulose chemicals for water treatment. The programme was composed of five interlinked work packages contributing to these selected focus areas (see Figure 1). The programme’s value-chain approach aimed at building technologies and expertise in dissolution, regeneration and product development within the selected areas, thus providing a platform for future value creation for the Finnish forest industry and cellulose converting industry value chains. Concrete process concepts were built based on the selected research paths. Techno-economic evaluations were carried out for selected concepts and these guided the technical process development work throughout the programme. Market analyses provided valuable information on the value chains in general and on the value generation mechanisms of the selected value chains.

The first target of the programme was to develop a new process for the production of cellulosic staple fibres from dissolving grade pulp. The main emphasis was on sustainable, techno-economically feasible process concepts that could replace the current industrial NMMO-based lyocell process or viscose process. The research focused on two approaches: ionic liquid based dissolution and fibre regeneration, and water-based dissolution and fibre regeneration. The ionic liquid based process development drew on the knowledge on cellulose-dissolving ionic liquids developed (at University of Helsinki) and the new dry-wet spinning equipment line built (at Aalto University) by FIBIC during FuBio JR1. The research on water-based process development focused on generating basic understanding of the

factors affecting the dissolution and regeneration of pulp cellulose to state-of-the-art water-based Biocelsol system, which was used as a reference. In both approaches, special emphasis was given to demonstration of the properties of novel regenerated fibres in clothing applications and modelling the technical and economic feasibility of the most promising novel processes.

The second target of the programme was to develop processes for the production of two new high-volume products or product platforms based on cellulose beads, nonwovens and thermoformable structures from dissolved cellulose, without the use of spinning regeneration. The end-product areas of focus were hygienic products, packaging, and medical component carriers, all selected based on market studies carried out in the programme. The research focused on processes for producing absorbing cellulose materials, thermoformable cellulose derivatives and slow-release cellulose beads. Special attention was paid to economic factors and the properties of the cellulose materials produced. Demonstrations of the most promising materials were targeted in all of the focus end-product areas.

The third target of the programme was to develop a new process for producing a water-soluble, cellulose-based polyelectrolyte chemical product. The research focused on the development of a techno-economically feasible synthesis route for cationic water-soluble cellulose derivatives from wood pulp. Two main synthesis lines – water-based and organic solvent based – were targeted after the initial screening phase. The most promising synthesis products produced at laboratory scale were tested as paper and/or water processing chemicals and benchmarked in selected applications against commercial reference chemicals.


Management of the programme

The FuBio Cellulose programme was administered by a Management Group (MG) comprising representatives from industry and academia. Execution of the programme was headed by a Programme Manager together with Industrial and Scientific Coordinators. Daily management tasks were performed in each Work Package (WP) under the leadership of the WP manager. The main tasks of the Management Group were to supervise the progress of the programme with respect to the objectives of the FuBio Cellulose programme plan, and to assess the scientific progress and techno-economic feasibility of the results. The MG had the following members:

• HeikkiHassi,Carbatec,untilMarch2013• EsaHassinen,UPM-Kymmene(Eeva

Jernström until September 2012) • MargaretaHuldén,Suominen• IlkkaKilpeläinen,UniversityofHelsinki,

Scientific Coordinator• KariKovasin,MetsäFibre,Chairman,

Industrial Coordinator• JukkaLaakso,Tekes• MarkkuLeskelä,FIBIC(LarsGäddauntilApril

2012)• JariRäsänen,StoraEnso• KariSaari,Kemira• AnnaSuurnäkki,VTT,ProgrammeManager

Dissemination of the FuBio Cellulose programme results was achieved with a number of different tools, the most important being the FIBIC research portal, accessible to the FuBio Cellulose programme participants, and the FIBIC Ltd website open to the wider public (http://fibic.fi/programmes/fubio-cellulose). Both internal and public programme seminars were held annually. The public seminars held jointly with the FuBio JR2 programme brought together experts from academic and industrial fields and provided a comprehensive overview of the research activities and results of both

the FuBio Cellulose programme and the whole Future Biorefinery entity in Finland.

Participants and international cooperation

The FuBio Cellulose programme brought together the leading forest cluster companies, selected value chain companies in nonwoven and staple fibre areas, and public research groups related to chemical pulping technology, cellulose material science, modelling and simulation and cellulose product applications in Finland. Six companies (seven until 2013)and six Finnish universities and research institutes participated in the programme. In addition, material demonstration work was also subcontracted from external partners. Industrial partners• Carbatec,withdrawn2013• FIBIC• Kemira• MetsäFibre• StoraEnso• Suominen• UPM-Kymmene

Research organizations• LappeenrantaUniversityofTechnology• TampereUniversityofTechnology• UniversityofHelsinki• UniversityofOulu• VTTTechnicalResearchCentreofFinland• ÅboAkademi

International collaboration was integral to the FuBio Cellulose programme. The research and company networks generated play an important role in the further development of the wood cellulose based value chains and the Finnish knowledge base supporting this


development. The programme partners worked collaboratively with several research groups from five countries: Germany, Latvia, Poland, Portugal, Spain, and Sweden. Close links with the international scientific community will be maintained and strengthened in the future, particularly in the research areas of cellulose dissolution and regeneration as fibres by novel methods, chemical modification of cellulose and cellulose structure characterization.

Programme participants have been active in presenting the programme results at international conferences and workshops. Furthermore, programme results have been and will continue to be published in scientific journals as peer reviewed papers. The programme results have also been communicated with the value chain companies outside the programme consortium. The novel wood cellulose based textile fibres produced using the processes developed in FuBio Cellulose drew national attention in 2014 with the presentation of a dress manufactured from these fibres by design company Marimekko (see: http://fibic.fi/results).

Figure 1. FuBio Cellulose programme structure.

Dissolution of cellulose•Newionicliquidbasedprocesses•Newwater-basedprocesses•Modification

Cellulose-based chemicals•Celluloseactivation•Synthesisroutesforcationicpolymers•Synthesisofcationicparticles•Application&scale-up

New productsAbsorbents for hygiene productsThermoformable structuresProducts based on cellulose beadsMaterial demonstration

Markets and economics

Textiles and nonwovens via spinning regeneration•Regenerationtofibres•Modification•Nonwovens•Modellingcelluloseinprocessing

The FuBio Cellulose programme has been closely linked to the FuBio Joint Research 2 programme, especially in the development of cellulose dissolving ionic liquids. It is also the basis for the new Advance Cellulose to Novel Products (ACel, 2014-2017) programme of FIBIC Ltd. Many of the programme’s researchers have also been involved in other on-going, related national and international projects. This has ensured active information exchange and synergistic knowledge generation among the Finnish and international research community. FuBio Cellulose research groups participated, for example, in the European Community’s 7th Framework Programme projects and several COST actions.

The FuBio Cellulose programme’s results support industry-driven projects aimed at developing novel business based on wood cellulose. Active participation of industrial partners within the programme has ensured effective information flow from research to innovation, thus speeding business development among the participating companies.

C O N TAC T P E R S O N

Kristiina Poppius-Levlin, [email protected]

PA R T N E R S

Aalto University

Glocell

Lappeenranta University of Technology

Metsä Fibre

Pöyry Management Consulting

Stora Enso

University of Helsinki

University of Oulu

UPM-Kymmene

VTTTechnicalResearchCentreofFinland

IONIC LIQUID-BASED DISSOLUTION AND

REGENERATION PROCESSES


FUBIO CELLULOSE PROGRAMME REPORT

ABSTRACT

13

The main objectives were to develop novel sustainable ionic liquid-based (IL) solvent sys-tems with the capability to dissolve cellulose pulp of sufficiently high molecular weight to achieve the targeted mechanical fibre properties upon regeneration and to develop com-mercially viable cellulose staple fibre spinning processes for cellulose/IL solutions.

Detailed knowledge of the rheological behaviour of the IL-cellulose solutions, i.e. dopes, is a prerequisite for determination of the viscoelastic properties and further processing ofthedopes.Variouspulpsofdifferentgradeandoriginwereanalysedanddissolvedindifferent ILs. Obtained insights and knowledge of dope properties were crucial for the development of the spinning window, i.e. for the prediction of optimal spinning conditions.

The hitherto unreported and distillable IL [DBNH][OAc] proved to be an excellent solvent for the production of cellulosic fibres with strength properties significantly higher than those of other man-made commercial fibres. Cellulosic textile fibres were produced with tensilestrengthproperties(>50cN/tex)exceedingtheinitialtarget(≥35cN/tex).Twode-monstration products were manufactured: a scarf made of eucalyptus pulp and a dress (in collaboration with Marimekko) made of Enocell birch dissolving pulp.

To assess sustainable chemical modifications of pulp cellulose prior to dissolution, a wide range of chemical reactions were carried out in commercially available and novel, distillable ILs. A sustainable acetylation process of pulp cellulose in distillable IL, i.e. [DBNH][OAc], was of high potential as the mechanical properties of the chemically modified and spun fibres were good. A new cellulose modification method – cellulose alkoxy carbonylation – was also developed using ILs as a direct dissolution solvent.

In recovery and recycling studies of [emim] [OAc], polymeric ultrafiltration and nanofilt-ration (NF) membranes as well as a TiO2 ceramic NF membrane gave good retention of organics while not retaining the IL. Reverse osmosis was able to remove some water from IL-water solution ([DBNH][OAc]). In addition, pervaporation showed potential as a method for separating water from IL. Testing with ion-exchange resins showed their potential to remove possible metals from spinning bath solution. The most promising concept for DIL (distillable IL) recovery was based on evaporation and distillation technology.

Keywords:carbonate cellulose, chemical modification, distillable ionic liquid, dissolving pulp, dry-jet wet fibre spinning, fibre, ionic liquids, ion-exchange, membrane separation, purification technology, lyocell process, nanofiltration, pervaporation, reverse osmosis, rheology, solute exclusion, sustainable


1. Work background

Increasing global demand for consumer goods is generating robust growth in the textile fibre market. Total fibre consumption in 2030is predicted to rise to more than 130 milliontonnes, with a predicted share of cellulosic fibreofca.30%.Pairedwiththestagnationofcotton production, this will create an annual shortage of 15 million tonnes of cellulosic fibre. This ‘cellulose gap’ opens up new opportunities for man-made cellulosic fibres. For the Finnish forest industry, wood cellulose upgrading to higher value products fits the strategic target of generating new uses for wood and wood-based fibres. The promising market trends in textile fibres have aroused interest and activity towards novel, wood cellulose-based regenerated fibre products. Accordingly, one of the strong platforms identified as the main outcome from the FuBio1 programme, which ended in May 2011, was “New knowledge on cellulose dissolution in novel, recyclable ionic liquids”. A further goal was set to convert the generated competences into market-driven value chains.

Many attempts have been made to develop alternative regenerated cellulosic fibre processes that are competitive or even superior to the well-established viscose process. So far, only one technology fulfilling these criteria, lyocell, is in industrial use. The process is based on pulp dissolution in N-methylmorpholine-N-oxide (NMMO) to form a spinning solution. However, certain intrinsic properties of NMMO render the solvent prone to thermal run-away reaction and cellulose degradation, thus necessitating an appropriate stabilizer. This limits the versatility of the process.

Approximately a decade ago, ionic liquids were identified as powerful direct cellulose solvents. Their thermal and chemical stability can be utilized to circumvent problems associated with

NMMO. Of the relatively few ionic liquids that have been studied, the majority are imidazolium based, thus having moderate thermal stability, and some reactivity towards cellulose via carbene formation. Moreover, only little progress in the formation of cellulosic fibres from IL solutions has been reported so far.

A big challenge for IL-based pulp dissolution and regeneration systems is efficient and economical IL recovery. ILs need to be circulated and reused efficiently. For this purpose, new, easily recyclable ILs also had to be developed as, for example, distillable ILs were not available.

2. Objectives

The main objectives were to develop novel sustainable ionic liquid-based (IL) systems with the capability to dissolve cellulose pulp of sufficiently high molecular weight necessary to achieve the targeted mechanical fibre properties upon regeneration. Chemical pulp modifications during dissolution were aimed at enhancing water uptake of the regenerated fibres. The overall goal was to develop commercially viable cellulose staple fibre spinning processes for cellulose/IL solutions and to improve the properties (fibrillation and mechanical properties) of the obtained regenerated fibres so that they can be demonstrated in textile structures. In order to develop an efficient, commercially and environmentally viable IL-based process, recycling of ILs is of crucial importance.


3. Research approach

The overall approach was to develop and demonstrate a novel IL-based textile value chain spanning from wood and chemical pulp production to pulp dissolution in ILs, fibre regeneration, yarn spinning and, finally, fabric production (Figure 1).

In the commercial lyocell process, pulp is dissolved in N-methylmorpholine N-oxide (NMMO) monohydrate (non-derivatizing solvent) to achieve cellulosic textile fibres.

To circumvent the problems associated with NMMO, the potential of different ionic liquids (IL) for the production of man-made cellulosic fibres was studied.

A commercially available IL, [emim][OAc] (1-ethyl-3-methylimiadzoliumacetate),knowntobeanexcellent cellulose solvent, was used for initial trials. Several dissolving pulps were dissolved and the rheological properties of the resulting solutions were assessed. An understanding of the factors governing the rheological properties of cellulose solution was of great importance for solution processing. Thus, a classical shear rheometer to assess the viscoelastic properties

and an extensional rheometer to determine the elongational-rheological properties were used. The goal was to establish a relationship between pulp properties (molecular weight distribution), the rheological properties of the spin dope, and the spinnability. Spinnability describes the extrusion behaviour of the dope and the filaments’ stability in the air gap when stretched, i.e. extensional stress exerted.

The chemical stability of cellulose in the IL is important for the final fibre properties and for the development of a recycling strategy. Thus, respective pulp solutions in [emim][OAc] were tested with time-temperature degradation tests. All properties were compared to NMMO. Once a basic understanding was established, other ILs were tested. Besides known cellulose-dissolving ILs, promising novel, distillable ILs were developed and their suitability in fibre spinning was tested. Hence, respective pulp solutions were prepared and characterized in detail.

The strategy for chemical modification of pulp cellulose in ILs was to modify cellulose to low DS (degree of substitution) in order to

Figure 1. Ioncell-F textile chain – from wood to garment.


allow disruption of the crystallinity of cellulose and hence increase the water absorptivity of the resulting regenerated fibres. Similar incorporation of other alternative functionalities besides low DS may also afford novel properties and increased water retention. Therefore, the research approach was to look for sustainable chemical modification procedures for modification of cellulose in the chosen ionic liquid for fibre spinning. At the early stages the fibre-spinning process was not established, so a wide range of ionic liquids was tested. Many types of chemical modification were also tested to see which ones would be atom efficient, cause minimal degradation and be sustainable. It was initially intended that the regenerated cellulose properties would guide the development, but this approach proved impractical. Instead, it was found to be more effective to examine a wide range of chemistries to see which ones were suitable and then transfer these to the resource-intensive fibre spinning directly.

In the spinning trials, the commercially available ionic liquid [emim][OAc] was chosen as the first IL to be tested. Different dissolving pulps used in the lyocell process were used to benchmark the first results. Since the formation of a single monofilament is more straightforward, this was studied first. Subsequently, other novel volatile ILs were implemented. One new IL, [DBNH][OAc] (1,5-diazabicyclo(4.3.0)non-5-enium acetate)showed excellent spin stability, thus enabling the effects governing the multi-filament spinning process to be studied. Different pulps of lower quality (higher hemicellulose and residual lignin content) were also spun, and the effects of chemical cellulose modification on spin stability and fibre properties were studied. A comprehensive set of analytical tools was employed to shed light on the mechanisms of solution spinning and to characterize the resulting fibres not only in terms of their mechanical properties but also their (supra-)molecular structure.

In the functionalization of regenerated fibres, the goal was to improve fibre properties, such as to reduce fibre fibrillation, through chemical modification. In recent years, robust, quick, and high fidelity chemical reactions tolerating both water and oxygen have been developed under the context of click chemistry. Alongside this, irreversible adsorption of certain polysaccharides, such as carboxymethyl cellulose (CMC), is a well-established phenomenon. These two concepts can be combined to provide a generic modular platform. In the first step, modified polysaccharide chains with clickable functional groups were physically adsorbed on the cellulose surface. Second step was the actual click reaction, in which the desired molecule was covalently attached to the modified polysaccharide in-situ as already adsorbed on the surface.

To ensure the economic viability of IL-based pulp dissolution and regeneration systems, ILs need to be circulated and reused efficiently. Use of pressure-driven membrane separation processes for purification, recovery and concentration of ILs is one potential approach. To examine this approach, the filterability and tolerance of selected membranes towards the ILs – [emim][OAc] and distillable [DBNH][OAc] – were first studied. After identifying suitable membranes, their usability for removing impurities, such as carbohydrates dissolved during the process, was proved.

The efficient removal of water from the ionic liquids used in the cellulose dissolution process is also a prerequisite for the feasibility of the ionic liquid based fibre spinning process. Pervaporation proved to be a potential energy-efficient separation, purification and recovery technology for this purpose.

Preliminary techno-economic screening of DIL (distillable ILs) recovery concepts was carried out, including identification of different recycling concepts and estimation of the main production costs of the concepts.


4. Results

4.1 Programme pulps and ILs

PulpsThree different common pulps were selected for the programme in order to be able to compare results between different partners in the programme. Additional pulps were also used in different programme activities as necessary. The programme pulps were acquired, characterized with a number of methods and delivered to all partners in the programme (FBC-pulp1: Domsjö softwood sulfite pulp; FBC-pulp2: Eucalyptus urograndis pre-hydrolysis kraft pulp, Bahia Solucell; and FBC-pulp3: Borregaard sprucesulfite pulp) (Table 1).

Ionic liquids (ILs)The main ionic liquids used in the programme are shown in Table 2 and the structures are presented in Figure 2. In the case of the TMG

and DBN-based distillable ionic liquids, the propionate versions were also briefly studied.

4.2 Dope properties

Detailed knowledge of the rheological behaviour of the IL-cellulose solution, i.e. dopes, is a prerequisite for determination of viscoelastic properties and for further processing of the dopes. Various cellulosic solutes (pulps withdifferent cellulose content and intrinsic viscosity levels) were used for dope preparation. Figure 3 shows the complex viscosities and dynamicmoduli of three pulps in [emim][OAc]. Although the softwood and beech sulfite pulps have similar intrinsic viscosity values (540 and 520 ml/g, respectively) their respective IL-solutions differ significantly. On the other hand, solutions of the eucalyptus pre-hydrolysis kraft pulp (FBC-pulp2) and beech sulfite pulp are similar in terms of their viscoelastic properties although the pulp viscosities were different.

FBC-pulp1, Domsjö

Sulfite, SW/Spruce-Pine

FBC-pulp2, Bahia, HW/

Euca, PHK

FBC-pulp3, Borregaard,

SW/Spruce Sulfite

Viscosity, ml/g 520 470 1520

Kappa no 0.48 0.3 4.1

Glucan, rel% 89.8 95.8 90.8

Xylan, rel% 1.4 2.6 3.6

Mannan, rel% - - 2.1

Mn, g/mol (SEC) 47 600 34300 32100

Mw, g/mol (SEC) 405 000 358000 1307000

PD (Mw/Mn) (SEC) 8.5 10.4 40.7

Mn, g/mol (MALLS) 41300 62 900 67 200

Mw, g/mol (MALLS) 530500 196 400 792 000

DP<100, w% 4.1 3.7 7.3

DP>2000, w% 39 14.6 58.7

PD (Mw/Mn) (MALLS) 12.9 3.1 11.8

Crystallinity, % 54 59 -

Fibrils, nm (Lateral

dimens.)

4.2 4.8 -

Aggregates, nm 14.2 36 -

Table 1. Programme pulps and their properties.


Name of IL Abbreviation Comments, main uses in the programme

1-ethyl-3-methylimidazolium acetate [emim][OAc]] For dope property and rheological studies; benchmark literature IL

1-ethyl-3-methylimidazolium methylhydrogenphosphonate

[emim][MeHPO3] For IL phosphonate anionization of cellulose

N,N,N,N-tetramethylguanidinium acetate [TMGH][OAc] 1st generation distillable IL

1,5-diazabicyclo(4.3.0)non-5-enium acetate [DBNH][OAc] Dope property studies; current fibre-spinning IL

1-methyl-1,5-diazabicyclo(4.3.0)non-5-enium dimethylphosphate

[mDBN][Me2PO4] Alternative low-viscosity non-distillable structure for rheology testing

methyltrioctylphosphonium acetate [P8881][OAc] Phase-separable ionic liquid

Table 2. Main ILs used in the programme.

Figure 2. Main ionic liquids studied during the programme.

Figure 3. Complex viscosity and dynamic moduli of FBC-pulp2 (Euca PHK pulp, 470 ml/g) (blue); FBC-pulp1 (Domsjö 540 ml/g) (black), beech sulfite pulp (Lenzing, 520 ml/g) (red) in [emim]OAc (all solutions 10 wt-%, at 60°C).


It is known that cellulose undergoes degradation in IL solutions. To study the stability in detail, a 10 wt-% solution of eucalyptus pre-hydrolysis kraft pulp (FBC-pulp2) in [emim][OAc] was prepared and then stored at different temperatures for various periods. The solutions were then characterized in terms of rotational shear and extensional viscosity before the cellulose was regenerated and its intrinsic viscosity measured.

Figure 4 (a) reveals substantial degradation of cellulose at temperatures of 90°C or higher. However, the cellulose is not affected when stored at 60°C for 24 h. The cellulose degradation is reflected in the viscoelastic properties of the respective solutions (Figure 4 b) and can thus

Figure 4. DP of the regenerated cellulose of IL-cellulose solutions stored at different temperatures as a function of storage time (a) and Zero shear viscosity from respective solutions (b); DP calculated from the intrinsic Cuen viscosity.

a) b)

Figure 5. Molecular weight distribution (a) and zero-shear viscosity (full symbols) and crossover moduli (open symbols) as a function of COP-angular frequency (b).

be assessed without laborious regeneration of the cellulose. Extensional studies show a very sensitive response in elongational relaxation time to cellulose degradation. This is important for predicting the spinnability of various dopes. It should be noted that substantial degradation already occurs during the dissolution process. Thus, the effect of propyl galate (PG) as a stabilizer – as used in lyocell solutions – was studied. The addition of PG reduced degradation substantially.

In order to study the influence of molecular weight distribution on the spinnability of the resulting dope, different (native and degraded) pulps were mixed and dissolved in [emim][OAc] (Figure 5.) Only Blend 2 showed good spinnability.

a) b)


The zero-shear viscosity and the angular frequency and dynamic modulus of the crossover point (COP) of a cellulose-IL solution need to be within specific ranges to obtain successful spinning. A zero-shear viscositybetween27000and30000Pa·sandacrossover point between 0.8 and 1.2 s-1and3000and 5500 Pa, respectively, seem to be required. Furthermore, it seems that the spinnability of a cellulose-IL solution is very sensitive to the high molecular weight fraction of the cellulosic solute and to the polydispersity index (PDI). For successful spinning, a high molecular weight content greater than20%andaPDIhigherthan3appearedtobefavourable.

Main achievements• Obtainedinsightsandknowledgeofdope

properties were crucial for the development of the spinning window, i.e. prediction of optimum spinning conditions.

• Variouspulpsofdifferentgradeandoriginwere analysed and dissolved in ionic liquids. Even low-grade pulps were successfully spun in appropriate spinning conditions.

4.3 Chemical modification of pulp cellulose in ILs

In examining the chemical modification of pulp cellulose in ILs, several sustainable strategies were developed with the aim of imparting novel properties to the regenerated fibres, such as increased water absorptivity, reduced fibrillation or fire-resistance.

Cellulose etherification with epoxidesA typical reaction scheme for cellulose etherification, i.e. preparation of hydroxypropyl cellulose, is shown in Figure 6. Cellulose (typically 5-10% w/w) was dissolved in different ILs, typically [emim][OAc], [DBNH][OAc] and compositions of DMSO and [P8881][OAc] (0-40% w/w DMSO). After dissolution, propylene oxide was added (10 eq) and the mixtures were heated for a set time period.

Using recyclable IL systems, [DBNH][OAc] and [P8881][OAc] gave better product quality and cleanliness than [emim][OAc]. The reaction is, however, still not very atom-efficient (10 eq of epoxide used) and cellulose and ionic liquid were found to degrade to some extent under the used conditions, even in the presence of catalysts.

Cellulose alkoxycarbonylation using dialkylcarbonatesNew cellulose derivatives – cellulose alkyl (methyl or ethyl) carbonates – were successfully prepared (Figure 7). The optimum procedure for their preparation is by dissolution of cellulose in 10 wt% DMSO:[P8881][OAc] (phase-separable ionic liquid electrolyte) and using dimethyl or diethylcarbonate. Reaction also succeeded in [P8881][OAc] and [emim][OAc]. Products with a DS (degree of substitution) up to 1 were obtained. However, [DBNH][OAc] did not give the desired product.

See-through and flexible cellulose methyl-carbonate films were successfully prepared by solvent casting from pyridine.

Corey-Kim oxidationCorey-Kim oxidation is a method of selectively converting alcohols to aldehydes or ketones. The reaction was confirmed to occur in LiCl/DMA (lithium chloride / dimethyl acetamide), but overall the amounts of cellulose soluble at the low temperatures required by the method, combined with the inability to recycle all reagents made it unlikely that this procedure could be transferred to the spinning dopes. Despite this being a novel and unpublished reaction in the literature, the decision was made not to continue this work.

Cellulose esterification using anhydrides or estersEsterification of cellulose with carboxylic anhydrides and esters was highly successful. A sustainable method of cellulose acetylation was developed. Fibres have been spun from these dopes and the initial results look promising.


Main achievements• Severalnew,potentialstrategiesfor

chemical modification of pulp cellulose in different ILs were developed.

• EsterificationofcelluloseinILswithcarboxylic anhydrides and esters was very successful. Fibres have been spun from the dopes and the initial results look promising.

• Transesterificationofaphosphonateionicliquid with cellulose produced water-soluble, film-castable and fire-retardant cellulose. Unfunctionalized cellulose was found to be regenerated by dispersing in dilute acid, resulting in a novel cellulose regeneration process.

• Alkoxycarbonylationofcelluloseusingthe green reagents dimethyl and diethylcarbonate succeeded in ionic liquids.

Figure 6. Typical cellulose etherification conditions and reaction in DMSO:[P8881][OAc].

Figure 7. Scheme for preparation of cellulose alkyl carbonates using dimethyl carbonate (DMC) or diethylcarbonate (DEC) in [P8881][OAc]:DMSO solutions.


4.4 Cellulose textile fibres via spinning regeneration

Production of staple fibres – Ioncell-F processA novel process for producing staple fibres from ILs was developed and named Ioncell-F(iber) in analogy to the lyocell process. Staple fibres from various pulps were produced successfully using a distillable IL ([DBNH][OAc]) as solvent. Optimized multi-hole spinnerets with a two-

stage conical diminution (first cone 60°, second cone 10°) and a spin capillary aspect ratio of L/D = 0.2 showed no melt fracture. Fibres spun from eucalyptus pre-hydrolysis kraft pulp (FBC-pulp2)-[DBNH][OAc] solutions and their extraordinarily high draw ratio are illustrated in Figure 8. Mechanical properties of Ioncell fibres are significantly better than those of other man-made cellulosic fibres, such as viscose, modal and lyocell (Tencel) (Figure 9).

Figure 8. Fibres spun from FBC-pulp2 (eucalyptus PHK)-[DBNH][OAc] solutions (a). Linear density (titer) and tensile strength (tenacity) of fibres spun from FBC-pulp2-[DBNH][OAc] solutions as a function of draw (b).

a) b)

Figure 9. Mechanical properties of Ioncell fibres in comparison to other man-made cellulosic fibres.


Figure 10. SEM (a) and GPC (b) analysis of fibres spun from FBC-pulp2 (eucalyptus PHK)-[DBNH][OAc].

a)

b)

Fibre analysisStandard fibre properties such as linear density (titer) and tensile strength (tenacity) were measured on a routine basis. In addition, orientation and crystallinity were measured via optical birefringence and X-ray analyses, respectively. Morphology was assessed by means of SEM. Similar to lyocell fibres, the Ioncell fibres showed high tenacity values that were retained under wet conditions. Crystalline and total

orientation that was high and increasing with the draw ratio. The fibres showed a typical fibrillar morphology (Figure 10, a). Also, determination of the molecular weight of the cellulose before and after spinning showed that there is no significant degradation during the spinning process (Figure 10, b). This is important not only for the fibre properties but also regarding purification and recycling of the IL.


Demonstrations of textile production A demonstration run was performed to demonstrate the applicability of the fibres for textile production. Ca. 20 litres of [DBNH][OAc] were synthesized at Helsinki University and approximately 300 g of Ioncell staple fibresspun at Aalto University. Together with the Department of Design (School of Arts, Design and Architecture, Aalto University) the fibres were ring spun to a yarn at the Swedish School of Textiles (University of Borås, Sweden), dyed and flat-bed knitted (Figure 11). Fibre and yarn properties are summarized in Table 3. Boththe IL-fibres and the IL-yarns have significantly higher tenacity than commercial viscose fibres.

The official presentation of the scarf (Figure 11g)attheFIBICannualseminar(autumn2013)attracted the attention of a Finnish textile and design company Marimekko, who expressed an interest in jointly producing a full garment. Fibres from birch dissolving pulp (Stora Enso) were subsequently similarly processed to produce a dress (Figure 12), which was exhibited at Marimekko’s Autumn and Winter Fashion show (Helsinki railway station, March 2014). This spin-off project of the FuBio Cellulose programme is summarized in a video available online (http://youtu.be/AGFDPyzN1C8).

Figure 11. Process steps during yarn manufacture and the final knitted product: a) carding of [DBNH][OAc]-spun staple fibres; b) sliver feeding to the drafting machine; c) preparing the roving; d) feeding the roving; e) ring spinning; f) plying; g) flat-bed knitted scarf.


fibre

yarn

[DBNH][OAc] viscose

linear density (dtex) 1.9 1.5

dry tenacity (cN/tex) 47 23

elongation (%) 9.4 22.5

fibre length (mm) 37 40

finish no yes

linear density (tex) 54.3 62.7

tenacity (cN/tex) 34.4 17.3

elongation (%) 7.4 18.2

CV(%) 13.6 9.1

Table 3. Properties of yarns spun from [DBNH][OAc] and commercial viscose fibres.

Figure 12. Marimekko’s multi-functional dress produced from 100% Ioncell fibre (birch).


Extensional rheology experiments have thus been conducted by means of a Capillary Break-up Extensional Rheometer (CaBER) to characterize the air gap phenomena. Once the filament enters the spin bath, a complex solvent exchange leads to the coagulation of the cellulose and formation of the solid fibre. The solvent exchange in the spin bath is suspected to proceed via spinodal decomposition, which largely preserves the molecular orientation created in the spin capillary and air gap. Batch experiments were conducted to study the diffusion kinetics of the solvent and anti-solvent. Upon solvent exchange, the water content in the filament increases gradually from the surface while, concomitantly, the solvent level decreases. This causes a radial gradient where the transition from filament to fibre passes through various gel-states (Figure13).Thesegelstateswereassessed in

Figure 13. Cut through a simulated filament in the coagulation bath. The graphs show the solvent and water content, respectively, as the coagulation proceeds. The solvent content decreases from blue to red. X-axis shows the radial distribution, y-axis along the fibre.

Structure formation processA better understanding of the effects and factors governing the structure formation of the cellulosic fibre, i.e. the transition from solution to solid state, is needed to tailor and improve the solvent-based spinning process. Several stages in the spinning process influence the final (supra-)molecular structure of the cellulose polymer chains in the fibre. Shear stress in the spin capillary causes pre-orientation of the polymers in solution. Thus, each prepared dope was subjected to a routine shear rheological characterization. When the liquid filament enters the air gap, the shear stress is released instantaneously and the polymer chains tend to re-assume a random-coil formation which leads to die-swell. This is counteracted by the draw acting on the filament. The exerted elongational stress causes a further orientation of the cellulose chains.


Figure 14. KS15 (left) and KS42 (right) piston spinning unit.

KS42 KS15

piston diameter 42 mm 15 mm

cylinder volume 500 ml 17 ml

extrusion velocity range 0.4 – 5.0 ml/min 0.007 – 0.06 ml/min

Table 4. Specification of spinning units.

terms of their elastic strength and moduli in order to determine the weakest point of the filament in the spin bath. It was shown that the structure formation can differ markedly due to different diffusion constants and gel strengths of different ILs.

New ILs were constantly tested for their suitability as fibre spinning solvents. In order to process

also small (lab-scale) amounts of IL and thus gain more flexibility, a small piston spinning unit (KS15) was integrated into the existing spinning line, thus enabling full use of all previously installed equipment (Figure 14). The piston speed was reduced accordingly to create the same shear stress conditions generated in the bigger unit (KS42). The characteristics are summarized in Table 4.


Main achievements• [DBNH][OAc]provedanexcellentsolventfor

cellulose fibre spinning.• ThemechanicalpropertiesofIoncellfibres

are significantly higher than those of other man-made cellulosic fibres.

• Thechemicalstabilityofthecelluloseandmechanical properties of the resulting fibres clearly exceeded the goals set at the beginning of the programme. Cellulosic textile fibres were produced with tensile strength properties (>50 cN/tex) exceeding theinitialtarget(≥35cN/tex).

• Differentdissolvingpulpswerespunsuccessfully with only minimal difference in final mechanical properties. Paper grade pulp was converted into textile fibres with tenacity values of 48 cN/tex.

• Twodemonstrationproductsweremanufactured: a scarf made of eucalyptus and a dress (in collaboration with Marimekko) made of Enocell birch dissolving pulp. The products were presented at the FIBICAnnualSeminarNovember2013andatMarimekko’s autumn and winter collection fashion show (March 2014).

4.5 Functionalization of regenerated cellulose fibres

The aim of the chemical functionalization of regenerated and spun fibres task was to give the fibres more added-value and better properties, such as reduced fibre fibrillation.

Crosslinking of spun fibresDue to the high orientation of Tencel (lyocell) fibres, the fibres have a high tendency for fibrillation. The degree of fibrillation can be taken as a direct indication of the abrasion resistance of the fibre. Results using click chemistry for crosslinking Tencel reference fibres to reduce the unwanted fibrillation tendency of highly oriented fibres showed promising results similar to those of

commercial triazine crosslinker (Figure 15). The fibrillation index was reduced from 2.5 to 1.0. Similar positive effects of crosslinking are also expected with other fibre types. Fibre crosslinking chemistries based on the adsorption of pre-modified CMC and click chemistry and those with commercial crosslinking agent 2-sodiumhydroxy-4,6-dichloro-1,3,5-triazineareshowninFigure16.

Main achievements• Pre-modifiedCMCswereirreversiblyadsorbed

onto regenerated cellulose fibres. Further functionalization of cellulose fibres was demonstrated using click chemistry reaction.

• Fibrefibrillationwasreducedusingaclick-chemistry based crosslinker.

4.6 Recovery of ionic liquids

Efficient recovery of ILs in IL-based solution and spinning processes is a prerequisite for an environmentally and economically feasible process.

Pressure-driven membrane separationsDifferent UF (ultrafiltration) and NF (nanofiltration) membranes were screened and tested for filtration of IL-water solutions and for removal of impurities, i.e. dissolved material, during the process.

Model solution (galactoglucomannan, GGM, representing carbohydrate impurities in the spinning bath) filtration tests were conducted in cross-flow mode with a polymeric ultrafiltration membrane (GM by GE Waters, USA) and a ceramic nanofiltration membrane (Inopor®nano by Inopor® GmbH, Germany) (Figure 17). With the ceramic membrane the flux was slightly better than that with the GM membrane and the model compound retention was also better. The normalized fluxes were more or less the sameatthebeginningoftesting(around13L/m2hbar) but remained higher with the ceramic


Figure 15. Fibrillation indexes of unmodified and crosslinked Tencel (commercial lyocell) fibres after mechanical abrasion test (ball bearing method).

Figure 16. Chemical crosslinking via triazole ring (click chemistry) (a) and chemical crosslinking via triazine ring (commercial crosslinker) (b).

a)

b)

R1=H, CH2COONa or azide groupR2=H, CH2COONa or alkyne group

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Figure 17. Filtration with the GM UF membrane (cross flow)(a); [emim][OAc]] 20w%/H2O 80w% + 1 g/L GGM, 7.5 bar, 25°C, initial feed volume 2.0 L, A = 100 cm2 and cross-flow velocity 1.7 m/s.Filtration with ceramic NF membrane (Inopore®nano TiO2) (cross-flow)(b); [emim][OAc]] 20w%/H2O 80 w% + ≈1 g/L GGM, 2.0 bar, 25°C, initial feed volume 2.0 L, A = 660 cm2andcross-flowvelocity0.3m.

a)

b)

membrane (10 L/m2hbar with the ceramic membrane and 7 L/m2hbar with the polymeric membrane, see Figure 17). This may be due to more fouling of the GM membrane during the filter test.

It is possible to remove polysaccharides almost entirely and monosaccharides (glucose) partially (more than 50%) by NF (nanofiltration) if the IL concentration is high enough (thus IL

is not retained, i.e., the solution can be purified from organic contaminants). UF (ultrafiltration) can be used as a preceding step, although it will not remove smaller molecules.

The filtration trial with real spinning bath solution was done with an NF 270 membrane in cross-flow. Sugars in the spinning bath solution were retained totally, but the IL was also 90% retained.


Reverse osmosisThe reverse osmosis (RO) process can remove water from the spinning bath solution up to about 30 wt%. This limit derives from theosmotic pressure of the IL/water solution, which would require even higher pressures to be used to overcome the osmotic pressure resistance. In this study the highest operating pressure was 50 bar. A 15 wt% solution of IL ([DBNH][OAc]) in water would give about 40 bar osmotic pressure, theoretically. Pressures above 50 bar would remove more water, but would be economically unfeasible due to energyconsumption.A30wt%solutionwouldgive about 80 bar osmotic pressure (at 25°C and if IL is dissociated completely) which is, however, already close to the recommended upper limits for RO membranes.

Metal removal by ion-exchange resinsA simple IEX (ion exchange) test to remove metals from the model spinning bath solution gave very positive results. SAC (Strong Acid Cation) exchange resin removed magnesium almost totally, whereas WAC (Weak Acid Cation) exchange resin showed significantly inferior performance.

Recovery of ionic liquids by pervaporationSeveral polymeric membranes were tested for the recycling of ionic liquids used in the cellulose dissolution process. Pervaporation (PV) tests with tri-1,5-diazabicyclo propionate([DBNH][CO2Et]) showed that PVA-TiO2 and PVA-PDMSmembraneswereabletoseparatewater from the [DBNH][CO2Et] / water solution. Also 1-ethyl-3- methylimidazolium acetate([emim][OAc]]) showed high selectivity to water permeation with PVA-TiO2 and PVA-PDMSmembranes. The membranes did not, however, tolerate mDBN-dimethyl phosphate ([mDBN][Me2PO4]). In summary:

1) [emim][OAc]] •PVA-TiO2andPVA-PDMSmembranes

from HZG (Helmholtz-Zentrum Geesthacht) tolerated [emim][OAc]] and were able to separate water from the [emim]OAc/watersolution(90wt%/10wt%)inthePVexperiments.

2) [mDBN][Me2PO4] •Noneofthesevenstudiedpervaporation

membranes tolerated [mDBN][Me2PO4].

3)[DBNH][CO2Et] •PVA-TiO2andPVA-PDMSmembranes

fromHZGandPERVAP2255-30membranefrom Sulzer tolerated [DBNH][CO2Et] in the preliminary experiments.

•PVA-TiO2andPVA-PDMSmembraneswereable to separate water from the [DBNH][CO2Et] / water solution (90 wt%/10 wt%) in thePVexperiments.

DIL (distillable IL) recovery conceptsTwelve DIL recovery concepts were identified together with the research groups. Preliminary production cost estimates of these concepts were analysed in six scenarios. In summary, energy and capital costs dominated the costs in all concepts, while evaporation of water made up the bulk of the energy costs. The lowest production costs were achieved in the concepts where IL was purified by distillation, followed by concepts with flotation and ion exchange based purification.

[DBNH][OAc] hydrolysis and recycling[DBNH][OAc] as the favoured distillable ionic liquid for Ioncell fibre spinning has a certain degree of hydrolytic instability. This is dependent on temperature and water content. IL hydrolysis is faster as the water content decreases and temperature increases. Successive cycles of pulp dissolution and regeneration in a batch reactor were undertaken to determine how


many times the IL can be recycled whilst still maintaining its cellulose-dissolving capability. It was determined that under batch dissolution, regeneration and drying conditions the IL could be reused seven times until the hydrolysis product reached a level preventing dissolution (15 mol% hydrolysis product). As compared to a dynamic process, the regeneration and recycling conditions under batch dissolution conditions allow much longer solvent residence times in contact with hot surfaces. Therefore, hydrolysis was greatly increased. Nevertheless, the hydrolysis product needs to be converted back to ionic liquid, and this requires a recycling step. This was demonstrated to be possible by preparing the hydrolysis product and converting it back to the IL in the presence of excess DBN and Amberlyst 15 (superacidic resin). This enabled recovery of [DBNH][OAc] (Figure 18), avoiding irreversible decomposition to the amide decomposition product.

Main achievements• Itwasproventhatmembranefiltration

and ion exchange resin processes can be used as building blocks for solvent recovery and recycling in novel cellulose processing techniques that utilize ILs.

- Nanofiltration (NF) membranes were effective at separating dissolved organics from IL-water solutions while not retaining IL ([emim][OAc]).

- Reverse osmosis (RO) was able to remove some water from IL-water solution ([DBNH][OAc]).

- Ion Exchange Resin (IEX) was highly effective at removing metals from IL-water solution

• Pervaporationwasshowntobeasufficientmethod for separating water from IL.

• [DBNH][OAc]canbereused7times.Acertain degree of hydrolytic instability is overcome by a recycling step that converts the hydrolysis products back to the IL.

• ThemostpromisingconceptforDIL(distillable IL) recovery was based on evaporation and distillation technology.

4.7 Techno-economic modelling of Ioncell fibres

The objectives of the techno-economic evaluations were to facilitate communication between researchers and decision-making companies,toidentifycentralR&Dneedsduringthe course of the programme, and to provide recommendations for further research. The techno-economic modelling of Ioncell-F fibres analysed the production of cellulosic stable fibres using dissolution and regeneration technology based on novel ionic liquids developed at the University of Helsinki. Lyocell staple fibre was selected as a reference both for the production concept and end-use market.

Figure 18. Hydrolysis and reconversion to [DBNH][OAc] under suitable experimental conditions.


Figure 19. Block-flow diagram of the IL-based staple fibre production process

Water

Dissolving PulpDC 90%

Fibres

Premixing

Thin film evaporation

Filtering

Spinning

Washing

Finishing

Drying

Evaporation

IL recovery

IL Distillation

Impurities

Makeup IL

The techno-economic modelling compared two ionic liquid based processes with the commercial NMMO process (Table 5). SPINCELL process concept included Ioncell-F process and ionic liquid recycling process using dissolving pulp and INTEGRATED process concept had kraft pulp as feedstock and the same ionic liquid to function both in hemicellulose dissolution and fibre spinning. NMMO refers to the dissolution solvent used in the process of producing lyocell fibres from dissolving pulp feedstock.

All studied cases showed good profitability at a lyocell staple fibre price above 2 000 EUR/t.

Steam consumption in the SPINCELL process was about 16% higher than the corresponding NMMO process. IL consumption in the INTEGRATED process was somewhat higher compared to SPINCELL. Optimization of ionic liquid recovery could lead to lower production costs via energy and IL savings. A block-flow diagram of the IL-based stable fibre production process is illustrated in Figure 19.

Of all the techno-economic modelling cases studied in the FuBio Cellulose programme, the Ioncell fibres received the highest scores in the qualitative opportunity assessment.

Process concept Feedstock Solvent

SPINCELL Dissolving pulp [DBNH][OAc]

INTEGRATED Kraft pulp [DBNH][OAc]

NMMO Dissolving pulp NMMO

Table 5. Studied process concepts.


Market opportunities were seen as promising, with a large global market, increasing demand for man-made cellulosic fibres and excellent product qualities recorded. However, technical feasibility still remains a question with several uncertainties related to ionic liquid performance, recyclability and availability. The strengths and weaknesses of Ioncell fibre production are summarized in a SWOT analysis in Figure 20.

Based on the techno-economic assessment, the key recommendations for further Ioncell fibre research are related to ionic liquid preparation and recycling and the impact of various impurities on the spinning process. In developing novel ionic liquids, researchers should take into account the industrial-scale availability and price of applied reagents. If the reagents are not commercially available, the complexity of the chemical synthesis to produce such chemicals should be evaluated. Whether the same ionic liquid is suitable for both hemicellulose dissolution and fibre spinning is likely to define

whether the fibre producer should use kraft or dissolving pulp as feedstock. The type and efficiency of the recycling concept has a great impact on total production costs, and thus should be studied as a top priority. Similarly, the maximum concentration of impurities in ionic liquids should be analysed in order to define the required level of IL purification, and thus purification costs.

5. Exploitation plan and impact of the results

Finland has a long tradition in the pulp and paper industry. The importance of the wood sector to the Finnish economy is reflected in the multitude of university faculties that belong to the leading institutes of wood technology and chemistry worldwide. Industrial and academic cooperation in the Finnish wood sector is truly outstanding, providing the perfect foundation for cutting-edge research and innovative products. With the pressure of globalization

Figure 20. SWOT analysis of textile fibre production via ionic liquids.

Helpful to achieving business success Harmful to achieving business success

Process related

STRENGTHS•Excellentfibreproductquality•Largemarketandgrowingdemandofman-

made cellulosic fibres

WEAKNESSES•ProcessconceptisnotyetdemonstratedIonic liquid performance and availability

still on a vague basis•Ionicliquidrecyclabilityremainsa

question•Noclearcostadvantagesforeseencompared to commercial NMMO process

Business environment related

OPPORTUNITIES•Promisingproductioneconomics•Politicalsupportforenv.sustainableandsafe

fibres and production processes is very strong•Integrationtopulpmillseemsfeasiblewith

mutual benefits•Flexibleproductlinewithopportunitiesfor

various raw materials and product specs.•Ionicliquidscreeningisstillatearlystage.Even

more promising solvents may be found.

THREATS•Pricecompetitivenessagainstlyocellin

niche applications and against viscose, cotton and other fibres in bulk textile end-uses

•Marketentrymaybedifficultduetoclosemarket with only few large players


and the accompanying shift of big production sites towards the southern hemisphere (especially South America, Indonesia and China), the need for new specialized products is urgent. The market for cellulosic fibres is growing fast due to rapidly industrializing nations, offering new possibilities for Finnish wood-based industry. The knowledge created by this project opens new opportunities to utilize a broad spectrum of different grade pulps for fibre spinning, enabling raw material costs to be saved and energy consumption in subsequent process steps to be reduced. This increases the economic feasibility and reduces the environmental impact of the entire process. Finnish companies are well positioned to take a leading role in the biorefinery concept. Stora Enso has already taken a lead by starting dissolving pulp production at its Enocell plant in Uimaharju.

The successful production of textile fibres from local biomass resources has attracted the interest of Finnish textile and design companies and has already led to close collaboration with the leading Marimekko brand.

The developed generic methodology for the chemical functionalization of regenerated fibres showed potential, and is expected to gain the attention of industrial viscose producers. However, the method has not yet reached the exploitation stage and further work is needed to gather additional data and to understand the full potential and feasibility of the new technique.

The ability to use membranes in ILs recovery is important when considering the use of ILs in cellulose dissolution processes. Pervaporation offers a potential energy-efficient separation, purification and recovery technology for biorefinery that can bring financial savings and competitiveness to producers. This finding is also of benefit to other industries using ILs as solvents.

6. Networking

The research was carried out jointly by Aalto University, Technical University of Lappeenranta, University of Helsinki, University of Oulu and VTT. Table 6 presents both theresearch partners and industrial partners and their roles in the programme.

Aalto University has initiated collaboration with the Department of Chemical Engineering, University of Porto, in elongational viscosity of cellulose-IL solutions. The University of Helsinki has collaborated with the University of Santiago in the development of analytics related to recyclable ionic liquids. The University of Oulu has collaborated with the Membrane Separation Processes Group of the Chemistry Faculty at Nicolaus Copernicus University (Torún, Poland) in the form of researcher exchanges in the area of pervaporation theory and research.


Partner Role

Aalto University

- Forest Products Technology (FPT)

- Biotechnology and Chemical Technology (BCT)

FPT: Pulp analyses, rheological characterizations

of spinning dopes. IL fibre spinning. Pulp and fibre

modification.

BCT: Modelling of ionic liquid hydrolysis kinetics

Glocell Quantitative economic modelling


- Separation Technology

Membrane filtrations

Metsä Fibre Industrial tutor. Defining, steering and providing com-

petence for the modelling. Providing industrial view

insight to techno-economic assessments

Pöyry Management Consulting Market study. Economic feasibility modelling. Busi-

ness potential evaluation

Stora Enso Industrial tutor. Providing industrial insight to techno-

economic assessments


- Organic Chemistry

•Preparationoflarge-scaleionicliquidsamples(for

Aalto spinning trials, for UO for pervaporation and

VLEstudies,forLUTmembranepurificationstudies)

•ChemicalmodificationsofcelluloseinILs

•Designingoptimaldopemodificationproceduresin

cooperation with Aalto

•UnderstandingILrecyclabilityincooperationwith

AaltoandVTT

University of Oulu

- Mass and Heat Transfer Process

•Pervaporationstudies

•Roleofpervaporationincellulosedissolutionand

regeneration processes

UPM-Kymmene Industrial tutor. Providing industrial insight to techno-


VTT •Molarmassanalyses

•Techno-economicscreeningofDIL(distillableionic

liquid) recovery concepts

•Processmodelling,ionicliquidbasedprocesses

Table 6. Partner organizations and their roles.


7. Publications and reports

Publications:

García, V., Valkama, H., Sliz, R., King, A., Myllylä, R., Kilpeläinen, I., Riitta L. and Keiski, R.L. Pervaporation recovery of [AMIM]Cl during wood dissolution; effect of [AMIM]Cl properties on the membrane performance, Journal of MembraneScience,2013,Vol.444:9-15.

Hauru, L. K. J., Hummel, M., Michud, A. and Sixta, H. Dry jet-wet spinning of strong cellulose filaments from ionic liquid solution. Cellulose, 2014. DOI: 10.1007/s10570-014-0414-0

Hummel, M., Michud, A., Tanttu, M., Asaadi, S., Ma, Y., Hauru, L. K. J., Parviainen, A., King, A. W. T., Kilpeläinen, I. and Sixta, H. Ionic liquids for the production of man-made cellulosic fibres – opportunities and challenges. Advances in Polymer Science, 2014, accepted.

Stépán, A. M., King, A. W. T., Kakko, T., Toriz, G., Kilpeläinen, I. and Gatenholm, P. Fast and highly efficient acetylation of xylans in ionic liquidsystems.2013,Cellulose,202813-2824.

Conference proceedings

Asaadi, S., Michud, A., Hummel, M. and Sixta, H. High tenacity cellulosic fibres from novel ionic liquid-cellulose solution by dry-jet wet spinning. Proceedings of the 13th EuropeanWorkshop on Lignocellulosics and Pulp, Seville, Spain, 24th-27th June 2014.

Hauru, L. K. J., Hummel, M. and Sixta, H. Fibre spinning from ionic liquid dope. Proceedings of the 12th European Workshop on Lignocellulosics and Pulp, Espoo, Finland, 27th-30th August2012, pp. 272-275

Hauru, L. K. J., Hummel, M., Michud, A., Asaadi, S. and Sixta H. High-strength (870 mpa) cellulose filament spun from ionic liquid. Proceedings of the 7th Aachen-Dresden International Textile Conference, Aachen, Germany,28th-29thNovember2013.

Hummel, M., Hauru, L. K. J., Michud, A. and Sixta, H. Mechanistic studies on the regeneration of cellulose from ionic liquid solutions. Proceedings of the 12th European Workshop on Lignocellulosics and Pulp, Espoo, Finland,27th-30thAugust2012,pp.284-287.

Michud, A., Arnoul-Jarriault, B., Hummel, M. and Sixta, H. Influence of molecular mass distribution on the rheological behaviour of cellulose/ionic liquid solutions during dry-jet wet spinning process. Proceedings of the 12th European Workshop on Lignocellulosics and Pulp,Espoo,Finland,27th-30thAugust2012,pp.134-137.

Michud, A., Hummel, M. and Sixta, H. Influence of molar mass distribution on the final properties of regenerated fibres from cellulose dissolved in ionic liquid by dry-jet wet spinning. Proceedings of the13thEuropeanWorkshoponLignocellulosicsand Pulp, Seville, Spain, 24th-27th June 2014.

Presentations:

Hummel, M., Michud, A. and Sixta, H. Structure formation of cellulosic material upon regeneration from ionic liquid solutions. (Oral presentation at the 243rd American ChemicalSociety (ACS) meeting, March 2012, San Diego, USA).


Hummel, M., Michud, A., Hauru, L. K. J. and Sixta, H. Ionic liquids as powerful tool to exploit renewable biomass. (Oral presentation at the Technoport conference, April 2012, Trondheim, NO).

Hummel, M., Michud, A. and Sixta, H. Solution state of cellulose in ionic liquids. (Oral presentation at the 245th American Chemical Society (ACS) meeting, March 2013, NewOrleans, USA).

Hummel, M., Michud, A., Asaadi, S., Tanttu, M. and Sixta, H. High tenacity cellulosic fibres via ionic liquid processing. (Oral presentation at the FuBioopenseminarday,August2013,Helsinki,Finland).

Hummel, M., Michud, A., Tanttu, M., Asaadi, S., Ma, Y., Hauru, L. K. J., Hartikainen, E. and Sixta, H. Rheological aspects of ionic liquid based fibre spinning. (Oral presentation for the Finnish section of the Nordic Rheological Society, March 2014, Espoo, Finland).

Hummel, M., Michud, A., Roselli, A., Tanttu, M., Asaadi, S., Ma, Y., Hauru, L. K. J., Hartikainen, E. and Sixta, H. Ioncell: From pulp to high-performance fibres via ionic liquids. (Oral presentation at the “Journée Scientifique desGDRs LIPs et Biomatpro: Liquides ioniques et polymères biosourcés“, April 2014, Sophia-Antipolis, France).

Michud, A., Hummel, M. and Sixta, H. Dry-jet wet spinning of cellulose/ionic liquid (IL) solutions. (Oral presentation at the 245th American Chemical Society (ACS) meeting, March2013,NewOrleans,USA).

Michud, A., Hummel, M., Tanttu, M., Ma, Y., Asaadi, S. and Sixta, H. IONCELL-F Ionic Liquid based Fibre Spinning. (Oral presentation at the FuBio seminar, April 2014, Espoo, Finland).

Mänttäri, M., Keiski, R., Pihlajamäki, A., Nakari, O., Valkama, H. and Turkki, A., Recovery of Ionic Liquid by Hybrid Membrane Process (oral), FuBio Cellulose Seminar: Cellulose activation, dissolution and fibre regeneration, ÅboAkademi,11thMarch2013,Turku.

Sixta, H., Hummel, M., Michud, A., Hauru, L. K. J., Roselli, A., King, A., Kilpeläinen, I., Froschauer, C. and Schottenberger, H. Progress in Processing Lignocellulose with Ionic Liquids. (Oral presentation at The 3rdInternational Cellulose Conference, October 2012, Sapporo, Japan).

Sixta, H. Progress in processing lignocellulose with ionic liquids. Invited lecture at the University of Leipzig, Institute of Chemical Technology,July2013,Leipzig,Germany.

Sixta, H. Progress in processing lignocellulose with ionic liquids. (Oral presentation at the FuBioJR2WP2summerseminar,August2013,Helsinki, Finland).

Sixta, H., Hummel, M., Roselli, A., Asaadi, S., Hauru, L. and Tanttu, M. Processing lignocellulosic materials in ionic liquids. (Oral presentation at the 3rd EPNOE InternationalPolysaccharide Conference, Nice, France, 21th-24thOctober2013).

Posters:

Hummel, M., Michud, A. and Sixta, H. Extensional rheology of cellulose-ionic liquid solutions. Extended abstract and poster at the Nordic Rheology Conference, 6th-8th June 2011, Helsinki, Finland.


Hummel, M., Michud, A., Hauru, L. K. J. and Sixta, H. Applicability of various ionic liquids in dry-jet wet spinning of cellulose solutions (poster presentation at the 5th International conference on Ionic Liquids, April 2013,Vilamoura,Portugal).

Michud, A., Hauru, L. K. J., Hummel M. and Sixta H. Dry-jet wet spinning of cellulose-ionic liquid solutions (poster presentation at the FuBio Cellulose seminar, June 2012, Espoo, Finland).

Michud, A., Parviainen, A., Hauru, L. K. J., Mutikainen, I., Kilpeläinen, I., Sixta, H., Hummel, M. and King A. W. T. Tailored ionic liquids for dry jet wet spinning of cellulose solutions (poster presentation at the FuBio Cellulose seminar, August 2013, Helsinki,Finland).

Michud, A. and Rissanen, M. From cellulose to textile fiber and a ready products (poster presentation at the SHOK summit seminar, May 2014, Helsinki, Finland).

Nakari, O., Pihlajamäki, A. and Mänttäri, M. Membranes for Recovery of Water-Ionic Liquid Solutions (poster), Fubio Cellulose internal seminar, 12th June 2012, Innopoli 1, Otaniemi, Espoo.

Nakari, O., Pihlajamäki, A. and Mänttäri, M. Membranes for Recovery of Water-Ionic Liquid Solutions (poster), Fubio Cellulose and JR2 joint seminar, 1st October 2012, Innopoli 2, Otaniemi, Espoo.

Tanttu, M., Michud, A., Asaadi, S., Ma, Y., Hummel, M. and Sixta, H. Textile application of cellulosic fibres from ionic liquid solution (poster presentation at the FuBio Cellulose TextileCompanyWorkshop31stOctober2013,Espoo, Finland).

Valkama, H., Niemistö, J. and Keiski, R. L. “Pervaporation in ionic liquid’s recovery: Effect of 1-Ethyl-3-methylimidazolium acetate onpermeability properties of hydrophilic polymeric membranes” (poster presentation at the FuBio Cellulose Programme Internal Seminar 12.6.2012, at the FuBio Programme Seminar 1.10.2012 and at the XXIX EMS Summer School on Membranes in Nancy, France, 11.7.2012; the abstract was also published in the abstract book of the XXIX EMS Summer School 2012).

Theses:

Benoît Arnoul-Jarriault. Influence of the molecular weight distribution of cellulose on the rheological properties of cellulose-ionic liquid solutions (Master’s thesis, 2012, Aalto Univeristy)

Hartikainen, Eeva. Solution state of cellulose in ionic liquids – A rheological study (Master’s thesis,2013,AaltoUniversity).

Saastamoinen, Jouni. Influence of the solute’s molecular weight distribution on the spinnability of cellulose-ionic liquid solutions (Master’s thesis, 2011, Aalto University)

Selg, Christoph. New amidinium, imidazolium and phosphonium ionic liquids for cellulose dissolution and modification, (Master’s thesis, 2012, University of Helsinki)

WATER-BASED DISSOLUTION

AND REGENERATION

PROCESSES


Marja Rissanen, [email protected]

PA R T N E R S

Aalto University


Metsä Fibre

Suominen

Stora Enso

Tampere University of Technology


University of Oulu

UPM-Kymmene




ABSTRACT

The objective was to develop novel, sustainable water-based dissolution and regeneration processes for the production of a cellulosic staple fibre, and to demonstrate the regenerated fibres in textile and nonwoven structures. The chosen water-based process was the Biocelsol process. The dissolution factors involved in the Biocelsol process were studied to generate new knowledge to support the development of novel up-scalable pre-treatment and dissolution processes. The studies showed that both mechanical and enzymatic treatments are needed in order to obtain a spinnable dope. The mechanical treatment opened up the pulp fibre matrix to enzymes, while the enzymatic treatment reduced the molecular mass of the cellulose for dissolution in sodium zincate. The novel combined mechanical shredding and enzyme pre-treatment developed decreased the treatment time and enzyme dosage significantly. Based on the pre-treatment studies, it is expected that the dissolution process can be up-scaled to the industrial scale.

The regeneration studies focused on trials of spin dope and spin bath additives for controlling the regeneration process. The maximum tenacity of the novel Biocelsol fibres (19 cN/tex) was achieved by using both spin dope and spin bath additives. This value was slightly lower compared to commercial viscose (22 cN/tex), but further optimization of the spin bath could increase the tenacity value. Enzyme recycling and removal of oligosaccharides from the pre-treatment filtrates as well as separation of acid and salts from the spin bath were demonstrated by nanofiltration. Two demonstration products, i.e. spunlaced non-woven sheets and a knitted hat, were manufactured from Domsjö softwood dissolving pulp. The processing properties of novel Biocelsol fibres were comparable to commercial viscose fibres.

The novel chemical pre- and post-modification methods were demonstrated to achieve improved solubility and/or water absorption of regenerated fibres. The fibres regenerated from the pre-modified (butylated) pulp had slightly lower tenacity (15 cN/tex) compared to fibres from unmodified pulp.Waterabsorption,measured in termsofswellingcoefficient,was300%for thebutylatedfibres, which was significantly higher than both the unmodified Biocelsol fibres (170%) and commercial viscose fibres (100%). Post-modification of the regenerated fibres further improved the swelling coefficient to 500-1200%.

In addition, the cellulose and hemicellulose molecular weight distribution was modelled as a function of process conditions in order to optimize conventional viscose fibre production.

Keywords:Biocelsol, modification of cellulose, nanofiltration, pre-treatment of cellulose, spunlaced nonwovens, modelling of viscose process


1. Work background

Global annual consumption of textile fibres reached 90 million tonnes in 2012 and is increasing continually along with population growth and rising living standards. Cellulose-based textile fibres (natural and man-made) have a comfortable texture and high moisture absorption and are thus used mainly in apparel and home textiles. Cotton is the main natural cellulose textile fibre, with an annual production yield of between 20–27 million tonnes. The total global area dedicated to cotton cultivation has barely changed for 90 years, yet yields have tripled during this period. This has been achieved through intensive consumption of irrigation water, chemical pesticides, insecticides, and fertilizers, and at no small ecological cost. Man-made cellulosic fibres (MMCF), such as viscose, modal, cupro, lyocell, acetate, and triacetate, are made from cellulose dissolving pulp. MMCF production stood at about 5 million tonnes in 2012, the majority of which was viscose fibre. Man-made cellulosic staple fibre production has increased markedly during the past 10 years at an average annual growth rate of 7.5%, compared to 3.2% for synthetic staple fibres.Total textile fibre production has increased 5.4% during the same period.

The viscose process was invented as early as 1892. In the process, dissolving pulp is first treated with caustic soda, then with carbon disulphide (CS2), and dissolved in diluted caustic soda. The cellulose solution is then spun using the wet spinning method. The process is relatively lengthy and cellulose undergoes degradation reactions during the treatment process. The final fibre quality is strongly dependent on the degree of polymerization (DP) of cellulose, the degree of substitution and the by-products present in the viscose solution. Models developed in the FuBio Cellulose programme for different viscose steps can be used for optimization of product quality or for determining optimal process conditions for specific product grades.

The viscose process also consumes large amounts of water and chemicals, of which CS2 is extremely volatile and highly toxic. One of the most promising sustainable water-based processes for the manufacture of MMCF is the Biocelsol process (WO 2009/135875 A1)developed at Tampere University of Technology. In this process, chemical pulp is pre-treated mechanically and enzymatically and then dissolved directly in sodium zincate (NaOH/ZnO) solution using a freezing/thawing cycle. The solution is then regenerated into fibres using the wet spinning method. The benefits of the Biocelsol process are the lack of CS2 in the process and the possibility to use existing viscose fibre plants for the manufacture of regenerated fibres.

In order to further develop the Biocelsol process, deep understanding of the starting material structure and cellulose modification and dissolution were needed. Development and up-scaling of the pre-treatment processes were also essential in order to decrease the energy demand and to minimize water consumption. The coagulation conditions were adjusted to enhance fibre properties such as tenacity. Modification tools needed to be developed in order to modify key regenerated fibre properties, such as water absorption and holding capacity for nonwoven applications.

2. Objectives

The main objectives were to develop novel, sustainable water-based dissolution and regeneration processes for the production of cellulosic staple fibres, and to demonstrate the regenerated fibres in textile and nonwoven structures. Examination of dissolution factors involved in the aqueous process aimed to generate basic understanding of the dissolution process used in the development of pre-


treatment processes. The modifications, both pre- and post-modifications, aimed to improve cellulose dissolution and regeneration as well as the properties of regenerated fibres, such as increased water uptake. The cellulose and hemicellulose molecular weight distribution modelling as a function of process conditions was aimed at optimizing conventional viscose fibre production.


The overall approach was to manufacture textile products and nonwovens from wood via the production of chemical pulp, pulp dissolution and regeneration using the novel Biocelsol method, and subsequent production of textiles and nonwovens, as summarized in Figure 1. The chemical pulp used was Domsjö softwood sulphite pulp (spruce-pine, viscosity 520 ml/g).

The dissolution factors were studied to support the development of up-scalable pre-treatment and dissolution processes for use in the novel Biocelsol process. The treatment time of shredding and enzymatic hydrolysis as well as the enzyme concentration were varied to evaluate the structural changes in the cellulose pulp fibre. The pore structure of untreated and

differently treated pulp was studied by means of solute exclusion, thermoporosimetry, and different NMR methods. Crystal structures wereevaluatedby13C CPMAS NMR and wide-angle X-ray scattering (WAXS) measurements. The nanoscale structure was examined with small-angle X-ray scattering (SAXS). X-ray microtomography was used to observe structural changes at the micrometre scale.

A novel pulp pre-treatment was developed to improve alkaline solubility without extensive reduction in chain length, and to reduce energy and water consumption. The state-of-art Biocelsol treatment was used as a starting point. Several up-scalable mechanical treatments and enzyme preparations and their combinations were screened and the applicability of the novel treatments was evaluated by means of solubility tests. The solutions were characterized by optical microscope and by measuring ball drop viscosity, the quantity of dissolved and undissolved content, and total cellulose content. The dissolution process during the freezing/thawing cycle was examined using an optical microscope equipped with a cooling stage. Spinning trials ranging from small scale (5 kg spinning dope) to large scale (60 kg spinning dope) were carried out. Factors affecting

Figure 1. The production chain – from wood to textiles.


filterability and degassing of the solution were studied. The effect of drawing and other spinning parameters were evaluated. In addition, the effect of spin dope additives and the content of the spin bath on the spinning process and on the fibre properties were studied. The linear density, mechanical properties, swelling coefficient, and fibre morphology were characterized from the regenerated fibres.

In order to obtain an efficient process system, the purification and circulation of pre-treatment process water and the spin bath was evaluated. Purification of the enzymatic pre-treatment filtrate from sugars, salts and dissolved oligosaccharides and separation of acids and salts from the spin bath were studied by means of nanofiltration tests.

Chemical pre-modifications of cellulose with different substituents were studied to improve the solubility of cellulose. Additionally, the pre-modification formed tags for a post-modification step (grafting, crosslinking, etc.). The spinning properties of pre-modified pulps were evaluated. TEMPO oxidation as pre- and post-modification was used to improve solubility and to create charged groups for better water absorption. In addition, post-modification routes, such as grafting and click-chemistry, were used to improve the water absorption properties or to functionalize regenerated fibres.

The Biocelsol fibres were demonstrated in spunlaced nonwovens and a textile product. Non-woven sheets were manufactured in lab-scale pilots from the state-of-art, novel and modified (with acrylic acid) Biocelsol fibres. The fibres were carded and the webs hydroentangled with high-pressure water jets. The processing properties of the fibres and the water absorption and tensile properties of non-woven sheets were compared to commercial viscose fibres.

Finally, a textile demonstration product was manufactured from the novel Biocelsol fibres.

In order to develop physico-chemical models for the different steps in the viscose process, detailed information about related reaction chemistry, side reactions and component properties was collected. Modelling of xanthation, ripening, and dissolution was carried out. A population balance based method was used for prediction of the molecular weight distribution of cellulose during alkali cellulose ageing. A high-order numerical method capable of extremely accurate prediction of the integral properties of the distribution was applied. The method was also capable of predicting the actual distribution shape even in complex states, such as multimodal distributions. Several scission rate models were proposed and evaluated against the experimental data.

4. Results

4.1 Development of a novel water-based cellulose dissolution process

The objective was to develop a novel, sustainable and techno-economically feasible water-based dissolution process for wood pulp cellulose. Dissolution factors were studied to generate new knowledge to support the development of pre-treatment and dissolution processes. The focus was on understanding the changes in the cellulose fine structure occurring during mechanical treatment (shredding) and enzymatic hydrolysis, and understanding the effect of process chemistry, including additives and physical parameters, on dissolution. The Biocelsol process was used as a model dissolution system.

Dissolution factorsThe experimental data showed that the mechanical treatment opened the pulp fibre


matrix not linearly but stepwise according to the treatment time. The cellulose structure broke down or collapsed after a certain amount of stress (mechanical shredding). The molar mass and viscosity results showed that a longer mechanical treatment time increased the susceptibility of the fibres to subsequent enzymatic hydrolysis. The solute exclusion method, used for determination of micro and macro pores in the fibre wall, showed that the mechanical treatment has a dominant effect on fibre swelling. The results were confirmed with X-ray diffraction, NMR-cryoporosimetry and thermoporosimetry analysis. The SAXS results showed a slight loosening of the microfibril bundles during the mechanical treatment. According to the WAXS and solid-state NMR spectroscopy results, the duration of mechanical treatment did not affect the cellulose crystal size nor the crystallinity of the samples. The crystallinity of differently pre-treated cellulose samples varied between 60-62%, whereas the crystallinity of untreated pulp was 54%. The slightly lower crystallinity of untreated pulp might be due to the dissolution of some amorphous material during soaking of the pulp sheets before mechanical shredding.

The aim of enzymatic treatment of mechanically treated pulp was to decrease the pulp weight average molecular mass (Mw) and thus viscosity to a targeted level (e.g. from 520

ml/gto360ml/gin30minutes).Theenzymatictreatment was found to first rapidly result in cellulose chain cleavage, leading to decreased viscosity. Prolonging the treatment time did not cause further reduction in chain length or viscosity but merely increased the amount of carbohydrates dissolved from the pulp. Based on this result the amount of accessible sites for enzyme seems to be the limiting factor for the degree of enzymatic modification. No effect of enzymatic treatment on the crystal size or crystallinity of cellulose was observed by the solid-state NMR spectroscopy studies.

The molar mass and pore size of pre-treated pulp were found to be the limiting factors for dissolution in the Biocelsol system. Analyses of the soluble and insoluble fractions showed that the soluble fractions had lower molar mass compared to the original pulp, whereas the insoluble fraction had the higher molar mass fraction. The solute exclusion method and thermoporosimetry studies showed that the mechanical treatment opened the structure up for enzymatic treatment, and a higher enzyme dosage resulted in larger pores in the pulp. The larger pores most likely allowed NaOH/ZnO to penetrate more efficiently into the pulp fibre, thus increasing the quality of the solution. The relationships between molar mass and viscosity and solubility in the Biocelsol systems are shown in Figure 2.

Figure 2. Effect of molecular mass (Mw) on viscosity of cellulose solution (alkaline solubility of the samples shown as %) (left) and on solubility (right). MX = time of mechanical shredding before enzyme treatment. E0, E1=commercial enzyme preparations used for treatment.

Figure 2. Effect of a) Mw on viscosity b) on solubiltiy

Fb-‐visc. Solub. %Mw E1, 1mg/g E1, 0.25 mg/g Mw E0 E1, 1mg/g E1, 0.25 mg/g

405000 405000 41368431 368431 66295540 2908 295540 97.347161263724 484 263724 98.87594230572 172 230572 99.378971212931 60 212931 100

404518.5 404518.5 46.300552301632 301632 49.943442

307629.5 307629.5 58.742995214167 214167 55.64942191074 436 191074 88.260604

0

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Figure 2. Effect of a) Mw on viscosity b) on solubiltiy

Fb-‐visc. Solub. %Mw E1, 1mg/g E1, 0.25 mg/g Mw E0 E1, 1mg/g E1, 0.25 mg/g

405000 405000 41368431 368431 66295540 2908 295540 97.347161263724 484 263724 98.87594230572 172 230572 99.378971212931 60 212931 100

404518.5 404518.5 46.300552301632 301632 49.943442

307629.5 307629.5 58.742995214167 214167 55.64942191074 436 191074 88.260604

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The Biocelsol system requires a freezing/thawing cycle during dissolution. The mechanically and enzymatically pre-treated pulp fibres dissolved through fragmentation without ballooning. Conversely, the untreated and only mechanically treated samples dissolved mainly by swelling and ballooning. Dissolution of the pre-treated samples started when the temperature reached 0 °C. The untreated pulp started to dissolve at a much lower temperature (-15 °C) compared to the mechanically and enzymatically treated samples, as shown in Figure 3. The mostimportant process parameters in the freezing/thawing cycle were the cooling rate, the lowest temperature of sample, and the duration of the sample at low temperature.

Pre-treatment process development Several up-scalable, cost-effective mechanical methods and commercial enzyme preparations and their combinations were screened. For example, a high-intensity homogenizator, horizontal agitated laboratory pearl mill, planetary ball mill, and ultrasound treatment were trialled for mechanical treatment, but none proved sufficiently effective.

Two novel mechanical treatment devices and two commercial enzyme preparations were found to have the most potential for the novel pre-treatments. The solubility of the novel pre-treated pulp was better compared to the solubility of state-of-art treated pulp, as shown in Figure 4. In addition, the novel pre-treatment enabled a significant decrease in enzyme dosage (0.25 vs. 1 mg/g), higher treatment capacity (200 g/20 min vs. 70 g/h.), and higher cellulose concentration in the solution (7wt% vs. 5.5wt%).

The pre-treatment consistency had no clear effect on dissolution in NaOH/ZnO. However, if mixing at high consistency could be carried out at higher speed, the resulting fibre-fibre interactions might achieve better results. The best pre-treatment process developed was up-scaled to 200 g/20 min and the sodium zincate dissolution process was up-scaled to 60 kg dope. It is now expected that both processes can further be up-scaled to the industrial scale.

Preliminary studies of enzyme recycling showed that some of the enzyme can be recycled. Two-stage filtration (NF270 and NF90

Figure 3. Microscopy images during dissolution of differently pre-treated pulp in NaOH/ZnO a) untreated, b) mechanically shredded (5h) and c) mechanically and enzyme treated. Upper row = 0 °C, lower row = -20 °C.


membranes) of the process water from the enzymatic treatment significantly improved the removal of dissolved organics and salts. The treated water had significantly higher purity, and fouling of the tighter NF90 membrane was remarkably reduced. The total organic content of the process water was about 8.2 ppm after the two-stage NF process (unfiltered process water over 1400 ppm). The conductivity was 6.2 μS/cm (at 25 °C) (unfiltered process water 52 μS/cm).

4.2 Regeneration of cellulosic fibres

The objective was to develop a commercially viable cellulose staple fibre spinning process for a water-based cellulose solution, and to demonstrate the advanced Biocelsol fibres

(prepared using the developed novel pre-treatment process) in a textile product.

Regeneration of novel Biocelsol dopesThe regeneration or coagulation of cellulose should proceed through the gelling process. If the coagulation process is too fast, the cellulose solidifies too quickly preventing the high draw ratios of as-spun fibres and resulting in low fibre tenacity. Spin dope and spin bath additives were tested for their effect on slowing coagulation and increasing the draw ratio.

The combined effect of spin dope and spin bath additives proved most effective for increasing fibre tenacity, as shown in Figure 5. A clear effect on fibre properties was also obtained when the degree of filtration was altered.

Figure 4. Drop ball time of the alkaline solution as a function of cellulose concentration of the solution (left), and SCAN viscosity of the pulp (right).

Figure 4 Drop ball time a) b)

Kuviin muutettu extruder -‐> novel ja Baker Perkins -‐> state-‐of-‐art

matalin matalinalfa, % kuula, s/20cm Liuokset alfa, % kuula, s/20cm

Novel mechanical tr. SCAN <220State-‐of-‐art mechanical tr. SCAN 240-‐250Novel mechanical tr. SCAN 250-‐260 SCAN, ml/g Koodi Novel mechanical tr.State-‐of-‐art mechanical tr.

6.05 32 200FBC-‐TUT254b 6.05 32

6.13 56 250FBC-‐TUT268 6.13 56

6.3 44 170FBC-‐TUT269 6.15 24

6.49 56 260FBC-‐TUT270 6.26 88

6.8 72 220FBC-‐TUT271 6.17 48

7 112 250FBC-‐TUT133 6.16 128

6.15 246.26 886.17 486.14 326.59 606.94 1166.16 1285.7 108

5.46 40

0 20 40 60 80

100 120 140

100 150 200 250 300

Drop

bal

l )m

e, s/

20cm

SCAN viscosity, ml/g

Novel mechanical tr.

State-‐of-‐art mechanical tr.

1x with 0.25 mg/g E1, 6.26%

1x + (1x with 0.25 mg/g E1) 6.13%

1mg/g E1, 6.16%

0

20

40

60

80

100

120

140

4.5 5 5.5 6 6.5 7 7.5

Drop

bal

l )m

e, s/

20cm

Cellulose concentra)on, %

Novel mechanical tr. SCAN <220

Novel mechanical tr. SCAN 250-‐260

State-‐of-‐art mechanical tr. SCAN 240-‐250

Figure 4 Drop ball time a) b)

Kuviin muutettu extruder -‐> novel ja Baker Perkins -‐> state-‐of-‐art

matalin matalinalfa, % kuula, s/20cm Liuokset alfa, % kuula, s/20cm

Novel mechanical tr. SCAN <220State-‐of-‐art mechanical tr. SCAN 240-‐250Novel mechanical tr. SCAN 250-‐260 SCAN, ml/g Koodi Novel mechanical tr.State-‐of-‐art mechanical tr.

6.05 32 200FBC-‐TUT254b 6.05 32

6.13 56 250FBC-‐TUT268 6.13 56

6.3 44 170FBC-‐TUT269 6.15 24

6.49 56 260FBC-‐TUT270 6.26 88

6.8 72 220FBC-‐TUT271 6.17 48

7 112 250FBC-‐TUT133 6.16 128

6.15 246.26 886.17 486.14 326.59 606.94 1166.16 1285.7 108

5.46 40

0 20 40 60 80

100 120 140

100 150 200 250 300

Drop

bal

l )m

e, s/

20cm

SCAN viscosity, ml/g

Novel mechanical tr.

State-‐of-‐art mechanical tr.

1x with 0.25 mg/g E1, 6.26%

1x + (1x with 0.25 mg/g E1) 6.13%

1mg/g E1, 6.16%

0

20

40

60

80

100

120

140

4.5 5 5.5 6 6.5 7 7.5

Drop

bal

l )m

e, s/

20cm

Cellulose concentra)on, %

Novel mechanical tr. SCAN <220

Novel mechanical tr. SCAN 250-‐260

State-‐of-‐art mechanical tr. SCAN 240-‐250

Figure 5. Tenacity and elongation of fibres at rupture.

KUITUJEN MEKAANISET OMINAISUUDETKeskiarvot, 20 kuitua Lujimman kuidun arvot Lujuus, cN/dtex Lujuus, cN/tex

Kuidun koodi Haude tarkennus Alfa, % Q, ml/minII ja III, m/min I, m/min Suulake, n

Suulake, L, mm

Suulake, L/D

Maksimivenytyksen säätö: I-‐ / II,III+

suulake-‐venytys

venytys-‐suhde

Teoreettinen hienous, dtex Venymä, %

Lujuus, cN/dtex

Hienous, dtex

Lujuus, cN/dtex Venymä, %

Hienous, dtex Small scale Large scale Reference

Spin dope additive

Spin bath additive

Spin dope and bath additives Filtration

Raw material

TUT154 Avilon BrMS 18.58 2.43 1.23 2.68 18 1.2TUT191 Lenzing nonwoven 18.57 2.1 1.78 2.25 19 1.84TUT134F-‐7 Ref sarja 2 5.95 4.08 26 20 100 0.15 2.9 II, III+ 1.00 1.30 1.31 20 1.30 1.40 1.60 19 1.22 1.60 16.00TUT134F-‐12 +DMAc sarja 2 5.95 4.08 26 20 100 0.15 2.9 II, III+ 1.00 1.30 1.31 21 1.35 1.36 1.49 18 1.47 1.49 14.90TUT133F-‐17 +DMAc sarja 1 6.16 3.93 20 15 100 0.15 2.9 II, III+ 0.78 1.33 1.69 22 1.34 1.92 1.60 20 1.32 1.60 16.00TUT133F-‐27 Ref sarja 1 6.16 3.93 20 15 100 0.15 2.9 II, III+ 0.78 1.33 1.69 17 1.43 1.62 1.48 17 1.41 1.48 14.80TUT208F-‐8 Ref pesuh.vesi 5.82 3.93 24.4 17 100 0.15 2.9 II, III+ 0.88 1.44 1.31 17 1.47 2.43 1.55 17 2.45 1.55 15.50TUT208F-‐15 5% etikk. pesuh. 10% H2SO4 5.82 3.93 26 17 100 0.15 2.9 II, III+ 0.88 1.53 1.23 19 1.17 1.50 1.36 20 1.28 1.36 13.60TUT208F-‐19 5% etikk. pesuh.vesi 5.82 3.93 27 18.1 100 0.15 2.9 II, III+ 0.94 1.49 1.19 24 1.08 1.42 1.44 24 1.35 1.44 14.40TUT299A-‐F8 10%;10% ei 6 3.04 12.5 8.9 100 0.15 2.9 II, III+ 0.60 1.40 2.04 19 1.42 2.16 1.57 19 2.18 1.57 15.70TUT299A-‐F11 10%;10%;5.7% ei 6 3.04 13 8.9 100 0.102 2.0 II, III+ 0.60 1.46 1.96 18 1.44 1.97 1.57 18 1.96 1.57 15.70TUT299C-‐F17 10%;10%;5.7% BV641 6 3.04 13.5 8.9 100 0.102 2.0 II, III+ 0.60 1.52 1.89 18 1.64 1.81 1.88 17 1.53 1.88 18.80TUT299C-‐F20 10%;10% BV641 6 3.04 15 11.5 100 0.102 2.0 I-‐ 0.77 1.30 1.70 21 1.35 1.73 1.43 21 1.62 1.43 14.30TUT299B-‐F26 10%;10%;5.7% TEGO 6 3.04 17.4 11.9 100 0.102 2.0 II, III+ 0.80 1.46 1.47 16 1.62 1.42 1.74 15 1.35 1.74 17.40TUT299B-‐F29 10%;10% TEGO 6 3.04 12.8 8.9 100 0.102 2.0 II, III+ 0.60 1.44 2.00 17 1.42 1.95 1.48 17 1.92 1.48 14.80TUT307F-‐g 10%;10% ekstr.sellu 5.9 86.24 20 13.3 2100 0.66 1.50 1.70 21 1.24 2.19 1.37 23 2.17 1.37 13.70

ekst. TUT315F-‐2 10%;10% 60 5.8 3.14 12.5 9.2 100 0.102 2.0 II,III+ 0.60 1.36 2.04 24 1.42 2.25 1.55 24 2.16 1.55 15.50ekst. TUT315F-‐7 10%;10% 90 5.8 3.14 12.5 9.2 100 0.102 2.0 II,III+ 0.60 1.36 2.04 21 1.53 2.20 1.59 22 2.17 1.59 15.90ekst. TUT315F-‐11 10%;10%;Al2(SO4)3 90 5.8 3.14 12.6 9.2 100 0.102 2.0 II,III+ 0.60 1.37 2.02 24 1.41 2.39 1.51 26 2.19 1.51 15.10

TUT329-‐2F-‐1 10%;10% suodatussarja 5.8 127.68 28.8 22.1 2100 0.102 2.0 I-‐ 0.74 1.30 1.71 27 0.92 2.18 1.19 24 2.12 1.19 11.90TUT329-‐2FBV-‐3 10%;10% suodatussarja 5.8 127.68 28.8 22.1 2100 0.102 2.0 I-‐ 0.74 1.30 1.71 29 1.03 2.45 1.20 26 2.71 1.20 12.00TUT329-‐1FBV-‐5 10%;10% suodatussarja 5.8 127.68 28.8 20.3 2100 0.102 2.0 I-‐ 0.68 1.42 1.71 23 1.07 2.44 1.42 20 1.92 1.42 14.20TUT329-‐3FBV-‐8 10%;10% suodatussarja 5.8 127.68 28.8 20 2100 0.102 2.0 I-‐ 0.67 1.44 1.71 20 1.33 2.45 1.56 18 2.49 1.56 15.60TUT329-‐5FBV-‐9 10%;10% suodatussarja 5.8 127.68 28.8 20.3 2100 0.102 2.0 I-‐ 0.68 1.42 1.71 18 1.36 1.91 1.49 15 2.05 1.49 14.90TUT329-‐4FBV-‐13 10%;10% suodatussarja 5.8 127.68 28.8 20 2100 0.102 2.0 I-‐ 0.67 1.44 1.71 21 1.37 2.34 1.54 19 2.49 1.54 15.40TUT 340F-‐1 10%;10% Enoalfa-‐arkki-‐M5-‐E 5.68 4.08 20 14.6 100 0.15 2.9 I-‐ 0.73 1.37 1.62 19 1.21 2.10 1.46 20 1.95 1.46 1.46TUT339F-‐5 10%;10% Enoalfa-‐nd-‐M5-‐E 5.92 3.93 20 14.8 100 0.102 2.0 I-‐ 0.77 1.35 1.63 20 1.35 1.81 1.45 20 1.78 1.45 1.45TUT341F-‐8 10%;10% Enoalfa-‐arkki-‐extr.+E 5.44 8.7 41.7 31.4 100 0.102 2.0 I-‐ 0.74 1.33 1.59 21 1.24 3.44 1.39 20 3.38 1.39 1.39TUT342F-‐10 10%;10% Enoalfa-‐nd-‐extr.+E 5.2 6.9 28.4 20.8 100 0.15 2.9 I-‐ 0.62 1.37 1.77 21 1.14 2.40 1.33 22 2.65 1.33 1.33

0

5

10

15

20

14 16 18 20 22 24 26 28

Tena

city, cN/tex

ElongaBon, %

Reference

Spin dope addifve

Spin bath addifve

Spin dope and bath addifves

Filtrafon


A dope additive (alkylpolyamine polyoxyethylene glycol) was needed to remove the air bubbles from the filtered high-viscosity solutions. In addition, the dope additive enabled storage of the dope at ambient temperature for several days.

The fibre tenacity of the advanced Biocelsol fibres was 19 cN/tex (state-of-art Biocelsol fibre 13cN/tex).Fibrespinningwasscaled-upfrom50gto3kgoffibre.

Textile demonstrationThe applicability of the advanced Biocelsol fibres for textile products was demonstrated. The fibres were regenerated, spin-finished, and opened at Tampere University of Technology (TUT). The carding, ring spinning, and plying processes were performed at the Swedish School of Textiles (University of Borås, Sweden). The carding and yarn spinning properties of the advanced Biocelsol fibres were good due to the suitable crimping of the fibres. The crimps are formed during the regeneration stage and no further fibre crimping or texturization is needed.

The design of the textile product was produced by Studio Tint Ltd, Finland, and included the colour and pattern of the knitted textile as well as the model of a hat with an embroidered Biocelsol brand mark. The industrial-scale flat-bed knitting and sewing was done by Nevil Ltd, Finland. The knitted structure was dyed at TUT according to a dyeing recipe obtained from Nanso Ltd, Finland. The Biocelsol mark was embroidered by Brodeca Ltd, Finland. The demonstration textile product, a Biocelsol hat, is shown in Figure 6.

Spin bath recycling was studied using the two-stage nanofiltration (NF) process. In the first stage, dissolved oligosaccharides were removedwiththeopenNFmembrane(NP030,NP010 and NTR-7450). The oligosaccharide retentions were relatively low (<50%). In the second stage, salts and acids were separated with the tight NF membrane (Desal-5 DK and MPS-36), and only slight separation betweenacid and salts was achieved. Other membranes should therefore be tested to achieve efficient separation of spin bath compounds.

Figure 6. Biocelsol knitted hat.


4.3 Modifications

Chemical modifications were divided into pre-modifications, i.e. modification of the pulp prior to dissolution, and post-modifications, i.e. modification of the regenerated fibres. Some of the modification routes used are suitable for both pre- and post-modification. The objectives of pre-modification were to improve cellulose dissolution in NaOH/ZnO and/or improve the water absorption properties of fibres regenerated from the modified pulp. The objectives of post-modification were to improve the water absorption of regenerated fibre and to functionalize the obtained fibres. High water absorption properties are required for nonwoven products such as wipes, diapers, incontinence products, and feminine hygiene products.

The modification routes of cellulose (both pulp and regenerated fibres) are presented in Figure 7. Routes i, ii, and iv were used for pre-modification and routes ii, iii, iv, and v for post-modification. The chemical modification routes were:

i. Functionalization of cellulose with butyl groups containing reactive double bonds. These can be further cross-linked and grafted with hydrophilic monomers such as acrylic acid (AA) and/or 2-acrylaminomethylpropane sulfonic acid (AMPS).

ii. Functionalization of cellulose with allyl groups, followed by grafting or cross-linking as in route (i).

iii. Grafting of cellulose with hydrophilic monomers as in route (i).

Figure 7. Chemical modification routes: functionalization with (i) butyl or (ii) allyl groups followed by (iii) grafting, (iv) TEMPO oxidation, and (v) click chemistry.


iv. Oxidization of cellulose fibres, e.g. TEMPO oxidization. Cellulose is oxidized to cellulose derivatives containing carboxylic acid groups, which can be further modified for other functionalities or used as cross-linkable functionalities (pre- and post-modification).

v. Click chemistry

Modification of pulp and its regeneration into fibres For the dissolution and regeneration tests, 3-butoxy-2-hydroxypropyl(butylated,BinFigure7) cellulose and 3-allyloxy-2-hydroxypropyl(allylated, A in Figure 7) cellulose samples were prepared. The allylated sample with degree of substitution, DSA, 0.09 had higher solubility (7wt%) in NaOH/ZnO compared to the unmodified pulp (6wt%). Butylated pulp also

dissolved well in NaOH/ZnO. Due to the high surface activity of the pulp, extreme quantities of air bubbles were formed in the alkaline solutions, as shown in Figure 8.

The spin dope made from the butylated pulp regenerated easily into fibres. However, the spin dope made from the allylated pulp did not regenerated properly, and the allylated solution was thus mixed with unmodified solution in ratios 1/4 and 1/10 prior to spinning.

Tenacity and elongation of regenerated fibres from the modified pulps and reference pulp were at the same level. However, the swelling coefficient of the regenerated fibres from butylated pulp was huge compared to that of the other fibres, as shown in Figure 9. Water absorption values are measured as the swelling

Figure 8. Effect of mixing on the formation of air bubbles in alkaline solution from butylated pulp, a) mixed with a laboratory mixer and b) mixed by hand.

Figure 9. Water absorption capacity of the regenerated fibres as measured by swelling coefficient value.


coefficient, which indicates the amount of water that the sample is able to hold under centrifugation. For example, fibres regenerated from butylated pulp can absorb three times their own weight of water, whereas commercial viscose absorbs only its own weight of water.

TEMPO oxidation increased the carboxyl content of the pulp, and this could be further increased with NaClO2 treatment. The solubility of TEMPO-oxidized pulp fibres in NaOH/ZnO was higher compared to unmodified pulp. Unfortunately, the solutions made from TEMPO-oxidized pulp were not suitable for fibre regeneration.

Modification of regenerated fibresThe post-modifications reported in this chapter can be performed on all types of regenerated cellulose fibre. Reference and advanced Biocelsol fibres and commercial viscose fibres were used for the trials.

For non-woven trials, advanced Biocelsol fibres were first allylated and then grafted with different amounts of acrylic acid to obtain post-modified fibres containing poly(acrylic acid) (PAA)

chains. This route was based on etherification of cellulose fibres with substituents containing allyl functionalities, as shown in Figure 7 (ii). Fibres having reactive double bonds can be grafted in very mild aqueous conditions. Swelling ratio was improved up to 1200% (Table 1), meaning that 1 g of modified regenerated fibre can absorb 12 g of water. Water absorption properties were highest when the samples were converted into neutralized sodium salt form. The tenacities of the PAA grafted samples were slightly lower compared to the unmodified fibres (8 cN/tex vs. 11 cN/tex) as the grafted PAA increased the fibre weight (linear density in tex is defined as mass in grams per 1000 metres of fibre).

Modification with some anhydrides, such as maleic anhydrides, gives the fibres reactive double bonds, and at the same time enables the hydrophilic-hydrophobic balance of the fibres to be adjusted. The advantage of etherification is that ether bonds are rather stabile in acidic and especially in strong alkaline conditions. Ester bonds, as in the case of maleic acid derivatives, can be hydrolysed more easily

Table 1. Mechanical properties and water absorption capacities of the post-modified fibres measured by swelling coefficient value.

SampleWater

absorption capacity %

TenacitycN/tex

Elongation %

Reference samples

Biocelsol fibre 140 10.9 21

Lenzing viscose 80 22.5 19

Biocelsol fibres grafted with 32% PAA

Small-scale batch

in acid form 170 8.4 15

in neutralized form 1170 7.6 20

Bench-scale batch for non-woven trials


Biocelsol fibres modified with maleate

in acid form 160 6.0 13



in alkaline conditions. Some fibres with maleate substituents were prepared, but grafting of these fibres was not performed. The results are presented in Table 1.

Two different advanced Biocelsol fibre samples were TEMPO oxidized. The modification improved water absorption if the fibres were washed to Na+-form. However, oxidative treatment showed detrimental effects on the mechanical properties of regenerated fibre, as shown in Figure 10.

A click reaction can be used for post-modification of regenerated fibres, as shown in Figure 7 (v), and for functionalization of regenerated fibres. The irreversible adsorption

of CMC onto cellulose was combined with click chemistry (alkyne-azide cycloaddition) for preparing cross-linked Biocelsol fibres. First, an azide derivative and an alkyne derivative were adsorbed on the fibre surface. Next, the click reaction was executed to bring together the modified regenerated fibres via crosslinking reaction with the aim of improving the mechanical properties of the fibres. However, no improvement in mechanical properties was found to have resulted from the crosslinking.

4.4 Nonwovens from Biocelsol fibres

The objective of the non-woven trials was to test the processing properties of the Biocelsol fibres developed in the FuBio Cellulose programme,

Figure 10. Effect of TEMPO oxidation on the water absorbency (a) and mechanical properties of regenerated cellulose fibres (b).

a)

a)

Figure 10 Effect of Tempo

SwC, %Biocelsol Viscose

REF 176 107H+ 131 102Na+ 287 210

0

50

100

150

200

250

300

Biocelsol Viscose

Water absorp+

on cap

acity

,%

REF

H+

Na+

b)

Elong, % Tenacity, cN/tex

Biocelsol-‐REF 20,47 10,9Biocelsol-‐Na+ 12,63 8,6Biocelsol-‐H+ 15,47 9,20Viscose-‐REF 18,57 21Viscose-‐Na+ 7,30 9,90Viscose-‐H+ 7,66 11,00

0

5

10

15

20

25

0 5 10 15 20 25

Tena

city, cN/tex

Elonga+on, %

Biocelsol-‐REF

Biocelsol-‐Na+

Biocelsol-‐H+

Viscose-‐REF

Viscose-‐Na+

Viscose-‐H+

b)


and to characterize the properties of the obtained nonwoven sheets. The nonwoven sheets were manufactured by spunlacing (carding and hydroentanglement).

The processing properties of state-of-art Biocelsol and advanced Biocelsol fibres were comparable to commercial viscose fibres in carding and hydroentanglement carried out in pilot line for preparing spunlaced non-woven (Figure 11). Both 100% Biocelsol nonwoven sheets and 50% Biocelsol: 50% polyester blend nonwoven sheets were manufactured. The basis weights of the samples varied between 43-50 g/m2. Dry-state thicknesses were 0.5 mm for all non-blended samples, and 0.7 mm

for all blended samples. Wet-state thicknesses varied between 0.4–0.5 mm for non-blended, and between 0.6–0.7 mm for blended samples.

The water absorption properties are presented in Table 2. The absorption capacity (measured as swelling coefficient, Table 1) of the fibres does not translate directly into the absorption capacity of the nonwovens because a lot of the absorption correlates to the void space in the nonwoven structure. This can clearly be seen in the higher absorption of the 50% regenerated cellulose: 50% polyester blends compared to the nonwovens of 100% regenerated cellulose fibre. It is well known that the addition of synthetic fibres to a viscose mix increases the dry and wet thickness of the nonwoven, which is reflected in absorption increase. The highest absorptive capacity was reached with the 50% chemically modified Biocelsol: 50% polyester blend. This was, however, only a 15% increase over the comparable commercial blend, which cannot be considered a major improvement.

The mechanical properties of nonwoven sheets are presented in Figure 12. The tensile strength values of nonwovens made from Biocelsol fibre were lower compared to nonwovens made from commercial viscose. The dry tensile strength of non-wovens made from 50% modified Biocelsol: 50% polyester blend was relatively good, but dropped to very low levels when wet.

Figure 11. Pilot line for preparing spunlaced non-wovens.

Table 2. Water absorption properties of non-woven samples

Property Basis weight

(g/m2)

Water absorptive

capacity (g/g)

Water absorbency

time (s)Fibre blend

100% Lenzing viscose 43.3 11.8 1.3

100% state-of-art Biocelsol 53.5 9.9 4.9

100% novel Biocelsol 49.5 10.9 1.5

50% viscose : 50% polyester 45.9 12.9 4.6

50% state-of-art Biocelsol : 50% polyester 50.6 12.1 2.4

50% advanced Biocelsol : 50% polyester 49.8 13.0 1.9

50% chem.modified Biocelsol : 50% polyester 44.3 14.8 2.2


4.5 Modelling of hemicellulose and cellulose chain length distribution evolution as functions of process conditions in the viscose process

Physico-chemical models were developed for the different steps involved in viscose fibre production (xanthation, ripening and dissolution). Although a limited amount of experimental data was available in the literature for development of the model, the model provided basic information in accordance with the literature, such as the relative concentration of different species, changes in the degree of substitution of cellulose, change in reactor pressure, etc. As an example, the simulated change in degree of substitution duringxanthationisillustratedinFigure13.

The degree of substitution was defined as the number of xanthate groups present on one anhydro-glucose unit of the cellulose chain.

Normally, fresh xanthated cellulose solution has DS values of 0.5–0.7 after 80–120 minutes of xanthation and seldom exceeds DS 1. The simulation results give DS 0.5–0.65 for the same xanthation period.

The evolution of molecular weight distribution (MWD) can be modelled by population balance models. Discretization of MWD into categories representing a certain DP range considerably reduced the computational time. A model for prediction of changes in MWD during alkali-cellulose aging was developed and different equations for polymer scission rate were tested. Promising results were obtained from the scission rate equation given below.

ScissionRate = k(1-exp[-((DP-1)/c)d].exp(-a.t)

Values of ‘k’, ‘a’, ‘c’, and ‘d’ are constant andtheir values were optimized. ‘DP’ is degree of polymerization and ‘t’ is ageing period.

Figure 12. Mechanical properties of non-wovens (MD = machine direction, CD = cross direction).

a)

0

20

40

60

80

100

Tensile strength MD, dry

Tensile strength CD, dry

Tensile strength MD, wet

Tensile strength CD, wet

Force (N)

100% viscose 100% state-‐of-‐art Biocelsol

100% novel Biocelsol 50% state-‐of-‐art Biocelsol : 50% PES

50% novel Biocelsol : 50% PES

b)

0 20 40 60 80

100 120 140

ElongaSon MD, dry ElongaSon CD, dry ElongaSon MD, wet ElongaSon CD, wet

Elon

ga/o

n (m

ax %)

100% viscose 100% state-‐of-‐art Biocelsol

100% novel Biocelsol 50% viscose : 50% PES

50% state-‐of-‐art Biocelsol : 50% PES 50% novel Biocelsol : 50% PES


Comparisons of experimental and model results for different ageing periods are shown in Figure 14. Continuous lines represent the experimental MWD, while dots represent the discretized categories from the model. As cellulose degradation takes place continuously throughout the viscose process, a model similar to ageing could be implemented for the other

Figure 14. Comparison of experimental (lines) and model (dots) MWDs for different ageing periods.

process steps For the model development, experimental MWDs from the other steps should be available for optimizing the parameters in the scission rate equations. The experimental method generally used for analysis of MWD does not provide very accurate results for the lower molecular weight range, which makes accurate MWD modelling more challenging.

Figure 13. Degree of substitution from simulation (xanthation).

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0 40 80 120 160

DS (n

umbe

r/AG

U)

Time (min)

Degree of subs6tu6on

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1 hr

dw/d

(log

Mw)

log Mw

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

4 hr

dw/d

(log

Mw)

log Mw

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1 hr

dw/d

(log

Mw)

log Mw

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

4 hr

dw/d

(log

Mw)

log Mw

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

2 hr

dw/d

(log

Mw)

log Mw

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

8 hr

dw/d

(log

Mw)

log Mw

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

2 hr

dw/d

(log

Mw)

log Mw

3 4 5 6 7

0.0

0.2

0.4

0.6

0.8

1.0

1.2

8 hr

dw/d

(log

Mw)

log Mw


Population balance based modelling has now been implemented to predict the evolution of molecular weight distribution of cellulose during alkali cellulose ageing. These models can be used for optimizing viscose process conditions for a certain end product quality.


The results obtained on the effects of enzymatic pre-treatment on molecular weight and fibre surface pores can be utilized in planning pre-treatments to activate cellulose for dissolution to advanced Biocelsol or other water-based systems, as well as for chemical synthesis. The results regarding combined mechanical and enzymatic pre-treatments indicate that there is a potential to decrease the enzyme dosage and mechanical energy usage and thus enhance the economic feasibility of mechanical-enzymatic pre-treatment. It is also expected that both the pre-treatment and the dissolution process can be up-scaled to the industrial level. Recycling of water, enzymes and chemicals in the Biocelsol process by membrane separation requires further development.

The results of advanced Biocelsol fibre regeneration and demonstrations of spunlaced nonwovens and textile products are promising. The unmodified and modified Biocelsol fibres have higher water uptake values compared to commercial viscose fibres. Applications for Biocelsol-based fibres should reflect this special property. However, the mechanical properties of Biocelsol fibres need further development. Further modification and improvement of the mechanical properties could be achieved, for example, by utilizing the reactive allylic double bonds of modified and regenerated fibres in suitable post-crosslinking and post-grafting techniques.

Replacement of the current viscose process with the novel water-based dissolution and regeneration process would reduce the environmental impact of regenerated fibre manufacturing. Price competitiveness, however, remains a key challenge for the implementation of Biocelsol fibre.

Process models of different viscose process steps could be used for optimizing process conditions and product quality. The information obtained from these models could, in turn, be used in the evaluation of various process alternatives during the development of new processes. The modelling work thus supports the development of more cost-efficient and environmentally friendly processes, which is not only beneficial for industry but also for the environment and society. New process understanding gained through modelling could also be used in teaching at university level.

6. Networking

The research was carried out jointly by research organizations, Finnish forest cluster companies, and other companies. Table 3 presents theresearch partners and their roles.


Partner Role

Aalto University

- Forest Products Technology (FPT)

- Biotechnology and Chemical

Technology (BCT)

FPT: Characterization of pore structure (thermoporosimetry and solute

exclusion techniques); post-modification of regenerated fibres (click-

chemistry, TEMPO oxidation)

BCT: Physico-chemical modelling of viscose process steps.

Lappeenranta University of

Technology

- Separation Technology

Filtration studies.

Metsä Fibre Industrial tutor. Defining, steering and providing competence for the

viscose modelling.

Suominen Nonwovens Industrial tutor, manufacturing and characterization of spunlaced

nonwovens.

Stora Enso Industrial tutor. Giving industrial insight and steering of the work.

Tampere University of

Technology

-Materials Science

Solubility trials, SCAN viscosity measurements of pulp and regenerated

fibre, preparation of spin dopes, fibre spinning trials, management of

textile demonstration.


- Polymer Chemistry (PC)

- X-ray Physics (XP)

PC&XP:Characterizationoffibreporestructure(NMRmethods,X-ray

studies)

PC: Characterization of dissolution process.

University of Oulu

-Fibre and Particle Engineering

Experiments of mechanical treatments.

UPM-Kymmene Industrial tutor. Giving industrial insight and steering of the work.

VTT Mechanical and enzymatic treatments, factors affecting cellulose dissolution,

pre-treatment process development; pre- and post-modifications.



Publications:

Pahimanolis, N., Salminen, A., Penttilä, P., Korhonen, J., Johansson, L., Ruokolainen, J., Serimaa, R. and Seppälä, J. Nanofibrillated cellulose/carboxymethyl cellulose composite with improved wet strength. Cellulose 20(3),1459-1468,2013.

Grönqvist, S., Hakala, T. K., Kamppuri, T., Vehviläinen, M., Hänninen, T., Liitiä, T., Maloney, T. and Suurnäkki, A. Fibre porosity development of dissolving pulp during mechanical and enzymatic processing. Cellulose2014.DOI10.1007/s10570-014-0352-x.

Rissanen, M., Syrjälä, S., Vehviläinen, M. and Nousiainen, P. Solubility and solution rheology of enzymatically treated pulp. Annual Transactions of the Nordic Rheology Society, Vol.19,303-306,2011.


Presentations:

Grönqvist, S., Maloney, T., Kamppuri, T., Vehviläinen, M., Hakala, T.K., Liitiä, T., Hänninen, T., Suurnäkki, A. Activation of cellulose. Oral presentation in FuBio seminar, August25,2013,Helsinki,Finland.

Kamppuri, T., Vehviläinen, M., Grönqvist, S. and Rissanen, M. Novel regenerated cellulose fibres with high water absorption properties. Oral presentation in Ambience'14 & 10i3mConference, Sept 7-9, 2014, Tampere, Finland.

Kamppuri, T., Vehviläinen, M., Grönqvist, S., Setälä, H., Maloney, T. and Rissanen, M. Fabrication of wood cellulose – from pulp to textiles: Biocelsol. Oral presentation in FIBIC seminar April 15, 2014, Espoo, Finland.

Nousiainen, P., Vehviläinen, M. and Rissanen, M. Enzymatic Modification of Pulp Cellulose to Regenerated Fibres and Films via Aqueous Alkaline Solutions. Oral presentation in The Third Nordic Wood Biorefinery Conference, March 22-24, 2011, Stockholm, Sweden.

Rissanen, M. Sustainable Development in Textiles. Oral presentation in Cristal – Sustainable development in lifelong learning, June6,2013,Valkeakoski,Finland.

Sixta, H., Nousiainen, P., Vehviläinen, M. and Rissanen, M. From wood to structural materials: Regenerated fibres for textiles and nonwovens. Oral presentation in FuBio seminar, October 1, 2012, Espoo, Finland.

Vehviläinen, M., Kamppuri, T., Rissanen, M. and Nousiainen, P. Cellulose regeneration from aqueous solution. Oral presentation in FuBio seminar,March11,2013,Turku,Finland.

Posters:

Michud, A. and Rissanen, M. From Cellulose to textile fibre and a ready product. Poster presentation at SHOK Summit 2014, May 15, 2014, Helsinki, Finland.

Hänninen, T., Kamppuri, T., Vehviläinen, M., Grönqvist, S., Hakala, T.K. Dissolution of TEMPO oxidized pulps in aqueous alkaline solvents. Poster presentation in FIBIC seminar,November20,2013,Espoo,Finland.

Rajala, S., Kamppuri, T., Vehviläinen, M. and Setälä, H. Regeneration of modified cellulose into fibres. Poster presentation in FIBIC seminar, November20,2013,Espoo,Finland.

Waqar A., Kuitunen, S., Alopaeus, V. Modelling of xanthation kinetics during viscose process. Poster presentation in FIBIC seminar, November 20,2013,Espoo,Finland.

Rajala, S., Kamppuri, T., Vehviläinen, M. and Setälä, H. Regeneration of modified cellulose into fibres. Poster presentation in FuBio seminar,August27,2013,Helsinki,Finland.

Penttilä, P., Kilpeläinen, P., Tolonen, L., Suuronen, J.-P., Sixta, H., Willför, S. and Serimaa, R. Effects of Pressurized Hot Water Extraction on the Structure of Birch Sawdust. Posterpresentation.COSTFP110513.05.2013-14.05.2013,Edinburgh,UK.

Penttilä, P., Kilpeläinen, P., Suuronen, J.-P., Willför, S. and Serimaa, R. Effects of pressurised hot water extraction on the nanoscale structure of birch sawdust. Poster presentation. Physics Days,14–16.3.2013,Espoo,Finland.


Maloney, T., Grönqvist, S., Hakala, T.K., Hänninen, T., Penttilä, P., Kamppuri, T., Vehviläinen, M., Serimaa, R. and Suurnäkki, A. Pore Analysis of Dissolving Pulps. Poster presentation at the FuBio open seminar day, August2013,Helsinki,Finland.

Rissanen, M., Syrjälä, S. and Vehviläinen, M. Nousiainen P. Solubility and solution rheology of enzymatically treated pulp. Poster presentation at The Nordic Rheology Conference, June 8-10, 2011, Helsinki, Finland.

Theses:

Penttilä, P. Structural Characterization of Cellulosic Materials Using X-Ray and Neutron Scattering, PhD thesis, University of Helsinki, 1.11.2013.ReportSeriesinPhysicsHU-P-D207.

Rajala, S. Regeneration of modified cellulose into fibres. Master’s thesis. Tampere University ofTechnology,5.6.2013.

PA R T N E R S

Kemira

Metsä Fibre


Stora Enso

Suominen

UPM-Kymmene


Katja Salmenkivi, [email protected]

TEXTILE VALUE CHAIN RELATED TO

FUBIO TEXTILE FIBRES



ABSTRACT

The key objective was to provide information on market prospects, needed end-use pro-perties, and value chain dynamics in order to help Finnish Bioeconomy cluster (FIBIC) part-ners focus their research investments on the most lucrative market areas. The project included a market assessment on textile and nonwoven fibres, as well as an analysis of the value chain structure and value creation in the apparel industry.

As the largest end-user of man-made cellulosic fibres, the apparel industry is a high-po-tential application area for the FuBio Cellulose fibres Ioncell and Biocelsol. Despite a clear trend towards more environmentally friendly and natural fibres, the industry is very price conscious with constant pressure from brand owners to trim the supply chain. Fibres that offer technical or cost benefits compared to existing products thus offer the greatest po-tential for success.

Successful entry into the apparel value chain calls for brand owner cooperation as early as possible in the development process. FIBIC partners should locate end users that are able andwillingtoengageinR&Dcooperationandprovideindustryinsightsregardingpotentialapplications and needed fibre properties.

Keywords:apparel, technical textiles, nonwovens, Ioncell, Biocelsol, man-made cellulosic fibres, market forecast, value chain


Figure 1. Scope of market and techno-economic analyses related to FuBio textile fibres.

13Ohjelmatunnukset

1. Work background

The target market for the novel fibres developed in the FuBio Cellulose programme (Ioncell and Biocelsol) is the global market for man-made cellulosic fibres. The increasing global demand for cellulosic fibres cannot be met by cotton alone. In addition, there are serious drawbacks related to the conventional viscose process, namely the use of extremely volatile and toxic carbon disulphide (CS2) and a complex process configuration. The lyocell process yields fibres with higher strength properties than other cellulosic fibres with an environmentally friendlier process. However, the solvent used in the process, NMMO, has low thermal stability and there is an increased risk of runaway reactions. The FuBio Cellulose programme aimed at developing novel processes for the manufacture of regenerated fibres, which yield intrinsic fibre properties superior to viscose fibres but with significantly less environmental impact.

Man-made cellulosic fibres are widely used in the textile and nonwoven markets. In the FuBio programme, Pöyry analysed cellulosic fibre consumption in three main segments: apparel, technical textiles, and nonwovens. The apparel industry represents over 70% of all fibre markets and thus this overview is exclusively focused on the textile fibre market and apparel value chain (Figure 1).

2. Objectives

The objective of this work was to analyse the market opportunities for novel cellulose products in textiles and nonwoven applications and to analyse the value chain structure and value creation in the apparel industry.


Market assessments and value chain analyses were carried out as desktop studies complemented by external expert interviews when applicable. All market assessments were conducted with close guidance from the industrial partners. The industrial partners also took part in workshops to define the frameworks and scope of the studies as well as in result reviewing and dissemination activities.

4. Results

4.1 Textile fibre markets

Synthetic fibres dominate the textile market with over 50% of annual fibre consumption. Cotton is the most widely used natural fibre, representing approximately a third of all fibre demand (Figure 2). In 2011, consumption of synthetic textile fibres was almost 20 times higher than in 1970. The main reasons for this dramatic growth are the low production cost of synthetic fibres, the development of novel synthetic fibre grades and the limited supply of cotton fibre. Man-made cellulosic fibres constitute approximately 5% of global fibre production.


Polyester

Cotton

PolypropyleneAcrylicsPolyamide

Wool

SilkOther synthetics

Cellulosics

Viscose

Other cellulosic fibres

Knitted and woven textiles

Nonwoven

ModalHigh purity nonwovenMicro-denierFlame retardantHygiene products

Pöyry Management Consulting Oy

Figure 2. Global consumption of textile and nonwoven fibres

Although man-made cellulosic fibres represent only a small share of global fibre consumption, they have several advantages compared to cotton and polyester, such as feel, wearer comfort, softness, smoothness, moisture absorbency and capability for fibre modification. The most significant factor limiting the use of man-made cellulosic fibres is the price difference compared to cotton and polyester. Price is typically the strongest driver of fibre selection, although the effect of trends and traditions cannot be underrated. The choice of fibre is always a compromise between cost and fibre properties. Different blends are generally used both to reduce the manufacturing price of the garment and to modify textile properties such as pilling, softness, washability, and durability.

The demand for textile fibres is estimated to grow along with population growth, GDP growth, and a growing middle class with rising disposable income, among other trends. The more the GDP of a nation grows, the more textiles are

consumed. The majority of the projected demand growth in textile fibres will be realized in the BRIC (Brazil, Russia, India and China) and booming Asian countries, to which manufacturing is also relocating. Today, over half of all man-made cellulosic fibres are produced in China. It should be noted that the apparel value chain as a whole is more energy and labour intensive than, for example, the chemical or automotive industries. Due to higher energy prices, higher labour costs, restricting legislation, numerous standards, and the complexity of EU policies, European producers struggle to compete against developing countries. Fibre innovations are therefore essential for business survival and research and development of man-made fibres is concentrated accordingly in the industrialised countries. Europe’s long-term opportunity is to form a hub of specialized fiber production, while commodities would be produced in countries such as Indonesia, India or Brazil.

Although man-made cellulosic fibres represent only a marginal share of today’s


total fibre production, there is one widely-known but disputed scenario that predicts strong growth for cellulose-based fibres (Figure3).This‘cellulosegap’scenarioisbuilton the estimation that one third of all fibres should be based on cellulose materials due to their softness and moisture management properties. ‘Gap’ refers here to the supply gap in cellulose-based fibres, to which current cotton production methods are unlikely to be able to respond. Cotton production uses over twenty times more water than viscose, needs four times more high-grade arable land and is one of the largest markets for pesticides. Although viscose fibres have traditionally had a significant price premium over cotton, this cellulose gap would provide an opportunity for man-made cellulosic fibres, including FuBio Cellulose fibres, as cotton substitutes. The global textile market is highly dependent on the general economic situation. In weaker conditions, apparel is one of the first segments

to suffer. The apparel industry is dominated by strong brands that dictate each step of the value chain. This has resulted in an industry ready to relocate, always seeking the lowest labour cost countries.

The key trends shaping the apparel industry include fast-moving fashion trends, mass consumption, increasing homogeneity of the sector, growing interest in environmental sustainability, and increasing demand for functional textiles. Global fashion trends are defined by a small number of players (e.g. Peclers Paris), which the majority of brand owners follow. Multinational retail chains supplying low-price, short lifespan products are among the strongest drivers of mass consumption and increasing homogeneity of the apparel industry.

Environmental sustainability and ethical consumerism have increasing influence in the textile industry, especially in the mature

Figure 3. Cellulose gap scenario1.1. Modified from

‘The Cellulose Gap’ by Gherzi, Feb 2011

0

20

40

60

80

100

120

140

160

1900 1920 1940 1960 1980 2000 2005 2010 2015 2020 2025 2030

Cellulose GapMMCF

Cotton

SyntheticFibres

Wool

Million tons



markets. Green products are gaining ground but remain niche, as the majority of consumers are unwilling to pay a premium. One means of justifying premium pricing and ensuring that products live up to environmental and ethical standards is labelling. One of the most well-known labels in the textile industry is the Oeko-Tex Standard, a globally uniform testing and certification system for textile raw materials, intermediate and end products at all stages of production. The importance of these standards and labels is emphasized with apparel items that are in close contact to sensitive skin, such as underwear and children’s clothing.

Increasing demand for functional apparel is interlinked with the development of technical textiles and materials. Functional textiles include smart features, such as responding to variations in body temperature and absorbing heat and body moisture to give the clothing a comfortable, dry feel. A common example is the Gore-Tex fabric.

4.2 Apparel value chain

Despite considerably varying end product requirements, textile supply chains share numerous close similarities and the apparel industry as a whole can be described using a single generic supply chain. The supply chains all use similar raw materials, which are further treated processed to gain specific characteristics. Most differences therefore occur at the consumer end of the chain. In the apparel industry, retailing plays a significant role in distribution, whereas technical and industrial textiles are typically a business-to-business market. The textile industry is strongly connected to the chemical industry throughout the chain, from fibre to finished product. The production of man-made fibres is an entirely chemical process, and many natural fibres require substantial amounts of pesticides, fertilizers and other chemicals for cultivation,

harvesting and protection during transport. Downstream processing also consumes substantial amounts of chemicals, including dyes for colouring and different finishes and preservatives for ready-made garments.

The apparel value chain studied in the FuBio Cellulose programme starts with pulp and cellulose fibre producers and ends with distribution and sales. In this overview, the beginning of the value chain is limited to viscose and lyocell fibres. After fibre production the fibre is spun into yarn, which is woven or knitted into a fabric and usually treated with finishing chemicals. Finishing can be also done after garment manufacturing or in both steps. Each step in the value chain, from pulp to garment manufacture, can be performed separately or be partially or wholly integrated (Figure 4).

Distribution and sales can be roughly divided into two parts: the ‘traditional apparel value chain’, where retailers buy ready-made garments from garment manufacturers with little influence on the value chain and the products, and the ‘new apparel value chain’, which is controlled by strong multinational brand owners.

The number of operators increases significantly towards the end of the apparel value chain (Figure 5). In the pulp production step there are only tens of operators, while in the retail step there are tens of thousands of operators. Pulp producers are often forward integrated with fibre producers due to demanding quality parameters, which makes switching costs notable resulting in notable switching costs between suppliers or fibre types. Also, barriers to entry are substantial in the dissolving pulp industry, for example, due to high investment costs of new plants, know-how issues and the length of the product approval process.

Viscosefibreproductionisheavilyconcentratedin China, with large companies dominating the


Figure 4. Integration of operations within the apparel value chain.

Pulp producer

(Viscose staple) fibre producer

Spinner Weaver/Knitter Finishing

Garment manu-facturing

Distribution and sales by Brand owner or Retailer

Integrated from the production of fibre to garment (Toray)

Integrated from yarn spinning to garment production (e.g. Bombay Rayon Fashions, Arvind)

Integrated from yarn spinning to weaving/knitting (e.g. Weiqiao, Alok Industries, Toyobo, Huafu)

Integrated from fabric manufacturing to retail (e.g. American Apparel)

Wholesaling by brand owner

Cotton, wool, silk etc. producer

Synthetic fibre producer

Design, marketing, advertising, supply chain managementIntegrated dissolving pulp and viscose production (e.g. Birla)


• Less than hundred operators

• Thousands of operators.• Focus in production is in China and rest of Asia • Strong consolidation trend

• Thousands of operators.• Focus in production is in China and rest of Asia•Strong consolidation trend

• Can be done by same operator as fabric or garment

• Low investment costs make it easy to establish new operators if needed• Tens of thousands of operators• Focus in production is in Asia

• Tens of thousands of operators both in retailing and brands. • Some strong brands are more significant than others and drive the consumption.

Amount of operators

Fibre producer Spinner Weaver/

Knitter FinishingGarment manu-facturing

Distribution and sales

Pulp producer

• ~30 Operators

Source: Pöyry, Interviews Pöyry Management Consulting Oy

Figure 5. Number of operators in the apparel value chain.


Figure 6. Geographical distribution of key companies in each step of the value chain.

market. In addition, China also accounts for the bulk share of global viscose demand. The number of yarn manufacturers, weavers and knitters is, on the other hand, substantially larger compared to fibre producers. The industry includes hundreds of large companies and thousands of operators, which are mainly located in China and the rest of Asia (Figure 6). Finishing is usually done by the same company as the weaving or by the garment manufacturer if finishing is applied to a ready-made garment. Overall, there is a strong consolidation trend throughout the fibre industry.

Garment manufacturing has notably more players than the previous steps in the value chain. The industry is very labour intensive and characterized by high cost competition. Relocating a garment manufacturing company is relatively cheap and easy, which is one of the reasons why the industry is in constant search of new locations with readily available cheap labour.

There are tens of thousands of operators in apparel distribution and sales. Consumption

and industry changes are driven by a handful of a relatively small pool of strong and influential global brands. Brand owners rarely own production capacity as it offers no competitive advantage, and contracts between garment manufacturers and brand owners tend to be short-term.

The vast majority of apparel industry companies are affected by fashion trends driven by strong consumer brands. These trends are transferred to yarn and fabric manufacturers through demand for certain types of products. Trends rarely impact fibre selection directly, since brands are unlikely to commit to a specific fibre type. However, trends can have an indirect effect on fibre demand. For example, a new trend for glossy garments will increase demand for viscose in fibre blends. The freedom to switch between fibre materials also serves as a dampener against price volatility. If, for example, cotton is readily available at a reasonable price, 100% cotton fabrics are used. If the cotton price soars, production costs can be easily cut by using blends of lower-cost fibres.

General retailer

Pulp producer

Brand retailerGarment manufacturer

SpinnerFibre producer

Weaver



Pulp producer Fibre producer Spinner Weaver/knitterGarment

manufacturerRetailer (general)

Retailer(brand owner)

Key bottlenecks determining competitive position

- Wood price and availability

- Pulp price- Price of

competing fibres

- Competing yarn producers

- Changes in material price/ availability (depending onflexibility&specialization)

- Competing fabric producers

- Changes in material preferences (depending onflexibility&specialization)

- Competing garment producers

- Strong bargaining and pricing power of brand owners

- Competing retailers

- Competing brands, private labels of retailers

- Threat of forward integration of big garment manufacturers

Sources of power & profits

- Cost competitiveness

- Technology advantage

- Wood procurement

- Price and price variability of cotton

- Quality (compared to synthetic fibres)

- Lowest cost producers have an advantage

- Verticalintegration to increase control and power

- Raw material flexibility


- Differentiation with high quality fabrics

- Verticalintegration


- Verticalintegration

- Marketing- Brand and

position of the retail chain

- Bargaining power of large retail chains

- Bargaining&pricing power through strong brand

- Control over the whole supply chain

Clock speed SLOW SLOW FAST FAST FAST FAST FAST

(Investment cycle, raw material price)

(Investment cycle)

(Labour price, competitors, fashion)



(Category management, fashion, colour industry)

(Fashion trends, colour industry)

Table 1. Competitive position of operators in the apparel value chain.

The bargaining power of big brands is overwhelming compared to suppliers, with practically no switching costs incurred in changing suppliers. The gap in bargaining power is not likely to narrow, rather the opposite, which has an impact on the profitability of all players in the upstream value chain. Table 1 summarizes the competitive position of different operators in the apparel value chain. The ‘clock speed’ analogy illustrates how different parts of a value chain operate with different cadences, or at different inherent clock speeds. In studying a long value chain it is not only important to know the speed of its different parts, but also to understand the key criteria determining this speed.

Integrated brand owner retailers are the most profitable players in the value chain, which emphasizes the strong position of brands in the apparel industry. Companies with strong brands have strong bargaining power towards their suppliers and can sell their products with higher margins. The high profitability

of integrated brand owner retailers further illustrates the global success stories of the rapidly growing ‘fast retailing’ companies such asInditexandH&M.Despitefiercecompetitionin apparel retailing, the big players are able to run their operations with reasonable margins.

The profitability of non-integrated companies located in the middle of the value chain (fibre, yarn, fabric, and garment) is generally lower than that of companies at the ends of the chain. Some vertically integrated apparel manufacturing companies have, however, reported relatively high profits. Although the number of fibre producers is significantly lower than that of apparel manufacturers, the value created by non-integrated fibre producers is rather poor. This can be partly explained by high raw material costs, strong competition and low switching costs between different fibre types, resulting in poor pricing power. Pulp and integrated pulp and fibre producers, on the other hand, have recorded solid financial results.


4.4 Conclusions

The apparel industry – the largest end-user of man-made cellulosic fibres – is an attractive application area for Ioncell and Biocelsol fibres. In addition, the proposed ‘cellulose supply gap’ scenario would have most significance in the apparel market where there is a clear trend towards more environmentally friendly and natural fibres. On the other hand, the apparel industry is highly price conscious, with constant pressure from brand owners to trim the supply chain. The market is dictated by fashion trends driven by strong brands, which also make most of the profit in the value chain. The beginning of the apparel value chain, especially fibre production, spinning and weaving, is concentrated in Asia, whereas the end of the value chain (brand and retailing) is located mainly in the West.

Operations in the middle of the apparel value chain are integrated in various ways. In general, the value chain as a whole is characterized by

heavy competition, especially on price and quality. Therefore, fibres that offer technical or cost benefits compared to existing products offer the greatest potential for success. Overall, integrated companies seem to have better profitability than companies focusing on only one step of the value chain. A major challenge for many industry operators is the volatile price and availability of cotton, which has an impact on the entire market from fibre suppliers to brand owners. The main bottlenecks for FuBio Cellulose fibre in the apparel value chain are related to politics and legislation, product quality, technology, and the fibre market (Table 2).

Successful entry into the apparel value chain calls for brand owner cooperation as early as possible in the development process. FIBIC partners should locate end users that are willing andabletoengageinactiveR&Dcooperationand provide industry knowledge and insights regarding potential applications and needed fibre properties. Cooperation with Marimekko is a major step in this direction.

Table 2. Main bottlenecks for FuBio Cellulose fibres in the apparel value chain.

Security of supply for viscose producers in China has to be ensured before you can build a new cellulose based fibre plant.

India and China can increase their protection of home markets thus making it impossible to export to these countries.

Politics /legislation

If the FuBio Cellulose fibre is expected to be technically similar to viscose, the quality barriers are:

A certain capacity is required to be able to get customers.

There are no high switching costs in the value chain for FuBio Cellulose fibre if the technical quality is similar to viscose.

Product quality

Technology

The availability of raw material for fibre producer has limited the production (dissolving pulps).

The volatile price and availability of cotton affects the whole fibre market.

Fashion trends can benefit or hinder the demand of the fibre.

Market

Wet strength is not good as for synthetic fibres

Highest yarn uniformity

Resistance to rubbing, abrasion, pilling

No hydrophobic properties



The work provided its industrial partners with important information on market prospects, end-use properties, and value chain dynamics that can be used to evaluate the opportunities and risks entailed in entering these markets. It also provided key recommendations and actions for achieving further development and market entry.

The results of the different market analyses were communicated not only to the industrial partners in question but also to all researchers in the FuBio Cellulose programme. Based on the overall results, successful market entry in the studied value chains requires proactive cooperation with brand owners, as the brand owners are the key decision makers in all of the studiedvaluechains. In2013,FIBICorganizeda textile value chain workshop in which selected brand owners took part in evaluating the industrial importance and applicability of the FuBio Cellulose results. As a result, new cooperation was initiated with several brand owners and FIBIC industrial partners.

According to the industrial partners, the market analyses provided essential information regarding the market prospects of the selected end-product areas of the Fubio Cellulose

programme. The results clarified both the market potential and barriers for the most promising products as well as the current supply and demand situation. The impacts of the market analyses from the industrial partners’ viewpoint can be summarized as:

- increasing understanding of the markets relevant to the programme, and

- increasing understanding of the value chains relevant to the programme

6. Networking

The market assessments facilitated communication between the researchers and industrial partners by bringing the latest research information into the business arena. As stated in the research plan approach, all work tasks were carried out in close cooperation between the industrial partners, research work package leaders and individual researchers. Key results were communicated to industrial partners and researchers during internal work package meetings, FIBIC seminars, and industrial partners’ internal meetings.

Table3presentstherolesofPöyryManagementConsulting and industrial partners in this work.

Partner Role

Kemira Industrial tutor. Defining and guiding the market assessments.

Metsä Fibre Industrial tutor. Defining and steering the value chain analysis. Defining and guiding

the market assessments.

Pöyry Management

Consulting

Marketassessment.Valuechainanalysis.

Suominen Industrial tutor. Defining and guiding the market assessments.

Stora Enso Industrial tutor. Defining and guiding the market assessments.

UPM-Kymmene Industrial tutor. Defining and guiding the market assessments.




Posters:

Rouhiainen, J. and Salmenkivi, K.Valuechainsand value creation: Case apparel value chain. Poster presentation at the FuBio seminar, August2013,Helsinki,Finland.

NEWPRODUCTS


Jaakko Hiltunen, [email protected]

PA R T N E R S

Glocell

Metsä Fibre


Stora Enso

Suominen



UPM-Kymmene


ÅboAkademiUniversity



The main focus was to develop novel absorbent cellulose materials for wiping and hygienic

applications and thermoprocessable celluloses for melt-spinning and extrusion coating by

industrially feasible methods. Furthermore, the aim was to produce functional beads from

wood-based cellulose.

A heterogeneous esterification process for producing thermomeltable cellulose esters from

different pulp materials at high pulp consistencies (15-25 wt-%) was demonstrated. The targeted

material properties, including good film forming ability and melt-spinnable formulations, were,

however, not fully obtained, likely due to the inhomogeneity of the starting materials. Melt

extrusion of the best synthesis materials by laboratory-scale twin-screw microcompounder

was successful, indicating that these materials could be utilized, for example, in injection

moulding processes. Commercial cellulose acetate butyrate showed very good spinnability in

the melt spinning process; the mechanical properties were comparable to polypropylene fibres.

The processability of the various commercial cellulose acetates in extrusion was good and

polymer films with good quality were produced.

Absorbent cellulose materials were easily produced at the kilogram scale. The results showed

that drying of chemically modified fibres is challenging when the target is to maintain improved

absorption properties. Hence, the drying process itself can be considered as a bottleneck in

developing novel absorbent materials competitive with currently used superabsorbents and

thus it needs further development. Processing of novel absorbent fibres by foam forming was

feasible and the foam-formed absorbent fibres were suitable for making novel nonwoven

structures by hydroentanglement. The absorbent fibres also provided improved water

absorption and water retention capacities in the evaluated fluff pulp compositions.

Physicochemically and chemically functionalized cellulose beads were prepared using an

environmentally-friendly water-based solvent. HyCellSolv pretreatment was developed for

making cellulose beads from different wood pulps. The method was successfully up-scaled

to meet the demands of the semi-pilot scale bead machine. Functional cellulose beads were

utilized as drug carriers. Drug delivery was studied with physicochemically modified beads,

oxidized anionic beads and CMC-cellulose blended beads. All of the beads demonstrated high

loading capacity and extremely good uniformity. In addition, controlled release from the beads

was recorded with various active pharmaceutical ingredients (APIs). The cellulose beads and

oxidized cellulose beads both showed excellent properties as drug carriers.

ABSTRACT

Keywords:absorbents, cellulose, cellulose esters, beads, extrusion, fluff, hygiene products, melt spinning, nonwoven, synthesis


1. Work background

Industrial processes for making cellulose derivatives are typically rather complicated multi-stage processes consisting of different activation, hydrolysis and purification steps, depending on the nature of the reaction and the targeted end-product properties. In addition, use of expensive high-purity pulps is typically a prerequisite, especially for the production of thermoprocessable cellulose materials. For these reasons most cellulose derivatives are too expensive to compete with conventional polymers such as polypropylene (PP), polyamide (PA) or polylactide (PLA). Simplification of the manufacturing process, reduced chemical consumption and use of cheaper raw materials are factors that could enable significantly lower market prices for cellulose derivatives. Additionally, general wet-lay methods for obtaining cellulose filament material have the problem of low productivity due to a low spinning rate. Therefore, a spun-lay process not using an organic agent is necessary for obtaining low-environmental-load fibres using cellulose as a raw material. Known examples of industrial thermoprocessable cellulose products applicable for melt spinning are plasticized cellulose acetate and cellulose acetate butyrate (CAB). However, these fibres are still mainly produced via spinning from acetone solution due to the different challenges associated with their melt spinning.

High volumes of absorbent fibres and nonwovens are used in producing hygiene products. In addition, superabsorbents (SAP) are used in high quantities in applications where high water absorption and/or water retention capacities are needed. Crosslinked polyacrylates, which can typically absorb 40 000–50 000% of distilled water and 4000-5000% of 0.9% saline solution by weight, are commonly used as SAPs in hygiene products. New and innovative personal care products require increasing amounts of

sustainable absorbent materials in different application forms. Fluff pulp is currently widely used as an absorbent in feminine hygiene products and nappies. The absorption capacity of fluff pulp cannot, however, compete with that of commercial SAP materials. If the fluff pulp absorption capacity could be increased, the use of SAPs could be reduced respectively. As SAP materials generally produced from oil-based polymers are significantly more expensive than fluff pulp, even partial replacement of SAPs by fluff pulp could positively affect both the cost and sustainability of the final product.

Fibre materials applied in disposable nonwovens are typically synthetic PET and PP combined with certain cellulose fluff pulp fibres. Rayon, once a common fibre in nonwovens, has now been largely replaced by synthetic fibres. Synthetic fibre blends are wet-laid along with cellulose for single-use fabrics. Growing concern regarding the sustainability of disposables has led to the creation of new biopolymer-based fibres that offer more environmentally responsible, performance-designed alternatives to the traditional oil-based fibres currently used in nonwovens manufacturing today. In technical applications, synthetic fibres are also being replaced with natural fibre, such as hemp or coir. The challenge of using cellulose fibres in nonwovens is their cost compared to synthetic fibres. Thus, the identification of suitable end product applications is key when aiming for increased cellulose incorporation in nonwovens.

Cellulose and modified cellulose matrixes can be used as carrier material for specific functionalities and for their controlled release. Cellulose beads, for example, can be used for various chromatographic and ion exchange purposes. The challenge of functional cellulose


beads is their biodegradability and techno-economic feasibility. Current solutions based on synthetic materials are, however, relatively expensive, which can provide a competitive edge for cellulose beads. In addition, benefits can also be found in the ability to produce biocompatible and very pure cellulose materials suitable, for example, for medical applications.

2. Objectives

The main objective was to develop i) functional cellulose bead structures from novel cellulose starting materials, ii) nonwovens with cellulose adsorbents aiming at minimum 4 000-5 000% water uptake for hygiene products and ii) extruded paper laminates and/or fibres from thermoplastic cellulose for nonwoven structures. The work aimed at demonstrating the performance of novel cellulose-based materials in target applications and facilitating their feasibility evaluation in WP5.


The focus was to develop novel absorbent cellulose materials for wiping and hygienic applications and thermoprocessable celluloses for melt-spinning and extrusion coating by industrially feasible methods.

Various routes formaking thermoprocessablecelluloses and cellulose water-absorbent materials were evaluated and critical technical parameters for material development were identified and investigated. Optimization and up-scaling of the most potential syntheses were carried out and the material applicability for the target end-use applications was evaluated. Economic evaluations were carried out to support the material development and to illustrate the technical feasibility and economic

viability of the optimized materials in the selected end-use applications.

Thermoprocessable celluloses consisted of novel cellulose esters and synthesized cellulose ethers as well as commercial cellulose acetates (CA) and cellulose acetate butyrates (CAB) as reference materials. Absorbent cellulose materials were prepared at laboratory scale by grafting hydrophilic monomers and/or allylated xylan to allylated cellulose fibres by TEMPO oxidation of the fibres or by dissolution and coagulation of cellulose as bead particles. Domsjö dissolving pulp was used in most cases as raw material, but high molecular weight Borregaard dissolving pulp, never-dried kraft pulp and Sigma’s commercial α-cellulose were also evaluated as raw materials. Mechanical, enzymatic and/or chemical pre-treatments were used as pulp activation methods to overcome the low pulp reactivity generally associated with the Domsjö dissolving grade pulp. Synthetized products were purified before material characterizations in order to remove chemical waste and unreacted reagents. Water absorption capacities were measured from air-dried and freeze-dried samples using standardized methods.

Nonwoven samples were prepared using two alternative web forming methods. Base structures were prepared from reference materials and novel absorbent materials using air-laid or foam-forming processes and the applicability of these methods for making controlled structures was evaluated. The intermediate structures were combined with a polyester web by hydroentangling on a lab-scale pilot line at Suominen Nonwovens Ltd. targeting 50:50 blends of absorbent material:polyester. The final samples were characterized (e.g. mechanical properties) and their performance was assessed against the


prepared reference materials, which imitated commercially existing products.

Beside nonwoven structures, novel fluff pulp compositions with improved water absorption capacities for use, for example, in nappies were targeted. Fluff pulp is typically produced via hammer milling of cellulose web. The same method was also used to prepare fluff pulps from foam-formed absorbent sheets. It was expected that the foam-forming method would be more suitable for absorbent material processing than conventional papermaking technologies. Finally, water absorption capacities and water retention capacities were measured from the samples.

Melt extrusion and melt spinning of selected commercial and novel thermoplastic cellulose derivatives were carried out with a micro compounder and laboratory-scale melt spinning line. The spinnability was studied by increasing the take-up velocity. The as-spun filaments were separately hot-drawn in an oven instead of the heated godet on the melt spinning line due to the small amount of polymer used. The fibre properties were characterized by an optical microscope and combined linear density and tensile tester equipment. The target of the small-scale and pilot-scale melt extrusion trials was to assess the processability of commercial and novel thermoprocessable cellulose compared to currently used synthetic plastics, such as PP, and to produce continuous film and moulded structures from novel thermoprocessable celluloses.

Cellulose bead structures were prepared by dissolving cellulose in environmentally friendly NaOH/urea solvent and coagulated via the sol-gel process in anti- or non-solvent using dropping or spinning drop atomization techniques. The bead structure design process included selection of flocculation media and

flocculation conditions, determination of the cellulose concentration of the solutions, functionalization of the bulk and surface of the beads, and control of micro- and mesopores and bead shape and size.

Chemical modification of the cellulose beads can be done either before or after coagulation. Both methods were applied. Heterogeneous modification was studied more intensively due to better stability and higher content of functional groups.

To evaluate the applicability of cellulose beads as slow-release drug carriers, the native and chemically modified beads were loaded with two model drugs, freely soluble (riboflavin 5`-monophosphate sodium salt, lidocaine hydrochloride monohydrate) and poorly soluble active pharmaceutical ingredients, APIs (griseofulvin and piroxicam). In addition, anionic beads were loaded with a cationic drug (Ranitidine HCl). Incorporation of model drug substances was achieved by immersing unloaded water-swollen beads in a solution of the drugs. In-vitro drug release with the loaded and dried beads was performed according to the USP paddle method. The drug content of the beads and the amount of drug released from them was investigated with a UV/Visspectrometer to determine the loading efficacy and drug release mechanism. The drugs incorporated in the beads were investigated in the solid state with field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR) to determine the crystallinity of the drug substances and the reasons for the different release profiles. The drug distribution in the beads was studied with a hyperspectral near-infrared (NIR) imaging device to clarify the drug release profiles.


Figure 1. Acetate laurate before and after melt-compressing at 200 °C. The formed film was transparent, homogenous and brittle.

!

4. Results

4.1 Thermoprocessable cellulose materials

4.1.1 Synthesis and processing of materialsThermomeltable cellulose esters and ethers were prepared using several synthetic routes. The aim was to obtain materials suitable for applications such as melt spinning and extrusion coating. Cellulose esters with specific end-product properties were prepared up to the maximum theoretical degree of substitution (DS 3). At least partial melting of materials byhot compression was observed in most cases, but the homogeneity of the materials was not fully comparable to commercial thermomeltable cellulose acetates and cellulose acetate butyrates, which were studied as references. Generally, cellulose hexanoates and cellulose laurates resulted in ductile melt-compressed translucent films when the degree of substitution was over 1.0. An example of the melt-compressed film is presented in Figure 1. Mixed esters of cellulose acetate hexanoates and cellulose acetate laurates typically contained a high number of acetate groups and only a low number of long-chain esters (degree of substitution, DS, 0.1-0.5). Figure 2 presents the DSC scans for the sequentially esterified cellulose hexanoate acetate sample (DStotal 2.0).

The raw material used for syntheses had a very significant impact on end product quality; especially materials made from high cellulose molecular weight dissolving grade pulp displayed very poor thermal melting, whereas esters from commercial α-cellulose were very homogeneous and resembled the commercial references. The synthesis product quality was slightly improved by pre-treatments. The molecular weight (Mw) and polydispersity (PD) of the materials were at the same level or lower than the references. It appears that uneven distribution of acyl substituents caused by irregularities in the starting pulp materials and possible transglycosylation reactions may partly explain the synthesis product heterogeneity. The current methods for determining DS values are not able to distinguish differences in substitution between the crystalline and amorphous regions of cellulose. Especially in the case of mixed cellulose esters, the order in which the substituents are added to the pulp cellulose can affect the end-product properties remarkably. Regioselectivity is typically determined by the size of the substituent, and large acyl groups, such as laurate groups, may not be able to react with highly crystalline regions of cellulose due to steric hindrance. It was observed that sequential and simultaneous addition of acetate and long-chain fatty acid substituents resulted in remarkably different


synthesis products. The order in which the acyl substituents were added was also critical for the thermal behavior of a sample.

The thermoplasticity and melt processability of the cellulose esters of hexanoate and laurate as well as the sequentially esterified celluloses (Acet-Hex and Hex-Acet) were tested with a twin-screw microcompounder at 170 and 200 °C. The cellulose ester was fed into the compounder and mixed for 5 min prior to forming a homogenous melt. The melt was extruded through a 2 mm diameter circular die. For the cellulose esters 170 °C was generally found to be too low a temperature to obtain desirable melt formation. Good melt formation was obtained with all cellulose esters and when the temperature was raised to 200 °C the esters exited the microcompounder in rod form. The cellulose hexanoate and laurate samples were opaque and broke when bent. The sequentially esterified celluloses showed better melt formation than the other cellulose esters. The sequentially esterified cellulose (Hex-Acet) resulted in a translucent and ductile rod, whereas the sequentially esterified cellulose (Acet-Hex)

resulted in a translucent but brittle sample (Figure3Aand3B).Interestingly,thesequentiallyesterified (Hex-Acet) melt was possible to draw as a fibre by hand. The rod diameter decreased from1.3mmtoa0.1mmfibrebydrawing(Figure3C).Thisindicatesthatthesequentiallyesterifiedcellulose hexanoate-acetate (Hex-Acet) is suitable for the melt spinning process. Based on these observations, sequential esterification enhanced thermoprocessability, unlike single esterification.

Etherification of cellulose was not successful using the method implemented to a high DS level(highestlevelachievedDS0.3).Thedryandhornified pulp sheets may require novel types of chemical or mechanical activation, such as strong swelling and/or partial dissolution, before higher DSs and reaction efficiencies can be achieved using the etherification method.

Melt spinning of commercial thermoplastic cellulosesThe quality of the synthetized materials was not sufficient for extrusion coating and melt spinning processes and, therefore, only

Figure 2. DSC (1st and 2nd heatings) thermograms for the cellulose hexanoate acetate before and after thermal processing with a microcompounder at 200 °C . Thermal processing at 200 °C had no effect on the glass transition temperature of cellulose hexanoate acetate.


Figure 3. The sequentially esterified celluloses processed at 200 °C: A) cellulose acetate hexanoate and B)cellulosehexanoateacetate(1.3mm)andC)hand-drawncellulosehexanoateacetatefibre(0.1mm).

commercial materials were used for making demonstration products. The melt spinning trials were carried out with a laboratory-scale melt spinning line. Two commercial cellulose derivatives, cellulose acetate (Plastiloid CA) and cellulose acetate butyrate (Sigma Aldrich CAB Mn 70 000), were used for the spinning trials. The spinnability of cellulose acetate was poor. The broad melting point caused a considerable gas formation at the spinning temperature (225 °C). The obtained filaments were weak and the maximum take-up speed wasonly30m/min.Thefilamentswerethick(160 μm) due to the slow take-up speed and low drawing of the filaments. Melt spinning of CAB was easier. Gas formation was rather low at the spinning temperature of 220 °C. The obtained filaments had better spinnability, and the maximum tested take-up speed was 800 m/min. The spinning trials showed that the spinning velocity of CAB could be even higher than 800 m/min. The diameter of the CAB filaments was about 25 μm, comparable to commercial textile fibres, but can be further decreased if needed. The visual appearance

of both cellulose derivatives was typical of melt-spun fibres. The spinning temperature had an influence on the mechanical properties of the CAB. The maximum tenacity value was 1.2 cN/dtex for fibres spun at 220 °C and only 0.4 cN/dtex for fibres spun at 240 °C. The tenacity values can be increased by hot-drawing. The maximum obtained tenacity value of subsequently hot-drawn CAB fibre was 6.4 cN/dtex, which is comparable to melt-spun polypropylene fibres. The hot-drawing trial as a spin-drawing process (with heated godets) was not as successful as the subsequent process. The tenacity value of the CAB fibre was only 0.7 cN/dtex, indicating that optimization of spin-drawing process conditions (godet temperature, velocity, linear density) would be needed. In melt spinning, the requirements for novel cellulose derivatives are narrow melting temperature, stability at melting temperature, high molecular weight, and narrow molecular weight distribution. This melt spinning work is one of only a few studies reported in the literature based on cellulose derivatives.

A B

C


Figure 4. Modelling scope for thermoplastic cellulose esters.

1) Kraft pulp 12) Kraft pulp 23) Dissolving pulp4) Sulphite pulp

Cellulose acetate/butyrate process

Lignocellulosic feedstock / Sugars

Melt spinning

Film extrusion

Modelling scope

VARIABLES1. Electricity price2. Oil price3. Chemicals, concentration

and price4. Biomass price5. Pulp price6. Hemicellulose price

Thermoplastic cellulose structures (granules)

PP

PLA

Crude oil

Crude oil PE

REFERENCE MATERIALS

Moulding

End-use examples:


4.1.2 Techno-economic modelling of thermoplastic celluloseThe objective of the modelling was to evaluate the techno-economic feasibility of thermoplastic cellulose in melt-spinning applications. The thermoplastic cellulose materials of focus were cellulose esters, more specifically cellulose-acetate-butyrate (CAB), cellulose-acetate-hexanoate (CAH) and cellulose-acetate-laureate (CAL). The modelling scope for material and energy balances and quantitative modelling was limited to thermoplastic cellulose granules. Common melt spinning materials polyethylene (PE), polypropylene (PP) and polylactic acid (PLA) were selected as reference products (Figure 4).

The commercial cellulose acetate process was used as a starting point for the modelled production concept (Figure 5). For all studied cellulose esters, raw materials constituted the largest part of the costs. The total production costs and the share of raw materials decrease with lower degree of substitution and with higher share of acetyl groups of total acyls. In this analysis, the modelled production costs of

thermoplastic cellulose esters were well above the market prices of the fossil-based reference products PE and PP.

The techno-economic modelling task also included an analysis of how the projected oil price development would alter the cost competitiveness of the studied cellulose esters. Although the correlation with oil price development is not as strong in the case of cellulose esters as it is in the case of PP, PE or even PLA, increasing oil price will also increase the price of thermoplastic cellulose. Therefore, increasing oil price is not expected to improve the cost competitiveness of cellulose esters considerably.

Although the modelled production costs of thermoplastic cellulose esters exceed the prices of commodity polymers, the costs are not prohibitive. Figure 6 summarizes the strengths, weaknesses, opportunities and threats of cellulose esters in melt spinning applications.


Figure 5. Block-flow diagram of cellulose acetate derivative production processes.

Activation

Esterification

Stopping

Acid Recovery

Hydrolysis

Precipitation

Washing

Press&Drying

Pulp

Butyric/Hexanoic/Lauric acid

Acetic acid

Acetic acid

Acetic anhydride

Waste water

Water

Water

CAB/CAH/CAL

Anhydride prod

Figure 6. SWOT analysis of thermoplastic cellulose in direct melt spinning.


Process related

STRENGTHS

•  Exis%ng commercial process (cellulose-‐acetate) as a pla6orm for a new product.

•  Would open melt spinning process for cellulosic materials.

WEAKNESSES

•  Product is not (and is unlikely to become) cost compe%%ve with currently used melt spinning polymers PE, PET, PP, PLA.

•  Compa%bility/suitability of studied material for melt spinning process is unknown.


OPPORTUNITIES

•  Demand for melt spinning products is increasing. •  Possibili%es for improved product proper%es, and thus, new end-‐use applica%ons.

THREATS

•  High subs%tu%on poten%al from compe%tors (PLA, Bio PE, etc.).

•  Nonwoven industry is very consolidated with only few players.


4.1.3 Markets and business opportunities for thermoprocessable celluloseMarket assessment of thermoplastic cellulose concentrated on five selected application areas divided into two categories: “short-term cases”, which focus on large volume end-uses where market entry is relatively simple, and “long-term cases”, which represent end-uses where market entry is more complicated or the product development time is expected to be long (Figure 7). The short-term end-uses include blister and other high-visibility packaging, shrink sleeve labels and films used in coated nonwovens, whereas long-term applications include food contact packaging with strict regulation requirements and cellulose nonwovens through direct melt spinning where the technical material requirements are challenging to meet.

Generally, the market opportunities for the product groups studied are lucrative. All examined markets are growth markets with

an interest in non-food based bioplastics. However, cost competitiveness remains a key challenge in all end-use sectors. Thermoplastic cellulose materials should be aimed at higher value applications instead of as a substitute for commodity polymers, such as polyethylene or polypropylene.

A blister can be defined as a local partition of a surface layer that causes a raised area on a flat surface that can hold items. The three main end-use segments for blister and other high visibility packaging are food, pharmaceuticals and consumer goods, such as toys and tools. Blister and other high-visibility packaging meets current product marketing needs extremely well. Being able to see what you buy is still considered one of the most important marketing instruments, particularly in consumer goods. Despite fierce competition in the packaging sector, blister and other high-visibility packaging is winning market share from other packaging solutions.

Shrink sleeve labels are film tubes that are applied over the head of a container and shrunk to the container shape using heat, hot air or steam. A shrunk-on label can be applied just to the shoulders or to the cap of the container, or it can cover the entire product to give 100% promotional area. This possibility is of particular importance in the food and pharmaceutical segments, where the amount of compulsory regulatory information on labels is ever increasing. Shrink sleeve tubes can be used to label, for instance, glass and plastic containers, aluminium cans, contoured packages or chilled and frozen products. Shrink sleeve labels are high-profile promotional tools and the fastest growing labelling category.

The film-coated nonwoven market is extremely performance oriented. Film is applied on top of the nonwoven to gain properties unattainable by the nonwoven or film on its own. Performance

Figure 7. Selected application areas for the thermoplastic cellulose market assessment.

Shrink sleeve labels

Food packaging

Film coated nonwovens

Cellulosenonwovens

through directmelt spinning Blister and other

high visibility packaging

Approximatemarket size



depends on the chemical formulation, coating thickness and weight, the number of layers, the form of the technical textile and the nature of any pre-treatments. Currently, there are very few bio-based materials in use in the coated nonwoven market. Increasing environmental concerns are generally tackled by reducing material consumption or replacing harmful substances,suchasPVC.

Food packaging is a promising market for bio-based materials, but also challenging due to strict food contact regulations. Material requirements depend strongly on both the packaging design and the type of food. For instance, confectionery boxes have very different packaging requirements from chilled ready meals. Changes in the global diet towards more meat and dairy are having their effect on the food packaging market. Overall, the market is strongly driven by consumer behaviour.

Spunlaid nonwovens and bioplastics are the fastest growing segments with compound average growth rates of (CAGR) almost 10% per annum. Annual growth rates of both short- and long-term end uses are summarized in Figure 8. Today, cellulosic fibres cannot reach almost half of the nonwoven market due to technical incompatibility. Direct melt spinning makes possible the combination of fibre production, web-forming and web-bonding in a continuous single-step process with much lower production costs and enhanced efficiency than, for example, in viscose-based nonwovens. However, the technical fibre properties are challenging to meet with cellulose-based thermoplastics.

The value chain analysis looked at the blister packaging value chain, which starts with the raw material producer and plastic manufacturer and continues with converter, brand owner and retailer. The converter and brand owner can be horizontally integrated and, in some cases, brand

0% 2% 4% 6% 8% 10%

Spunlaidnonwovens

Bioplastics,total

Film coatednonwovens

Shrink-sleeve labels

Bilster and other highvis. Packaging

Packaging,total

Foodpackaging

Annual CAGR

Long‐term

Short‐term


Figure 8. Annual compound average growth rates of selected end-use markets.

owners outsource their entire packaging function. The largest companies by turnover are found at both ends of the value chain, whereas the middle is characterized by a large number of small and highly specialized producers. Raw material producers and brand owners create most value in the high-visibility and blister packaging sectors. The magnitude of the captured value varies between end-use industries.

The blister market is highly price conscious, and there is little or no willingness to pay a premium for bio-based packaging in large-scale applications. New bio-based materials should be compatible with existing converting equipment, as there is low interest in developing and investing in new converting lines. The food, pharmaceutical and toy industries have strict laws and regulations, making market entry more difficult. However, the market is large and growing with a growing packaging trend towards more sustainable solutions.


Figure 9. Degree of polymerization as a function of time and temperature. Optical images demonstrate the dissolution mechanism in diluted CED solution.

4.2 Cellulose beads

4.2.1 Preparation and application of cellulose beads

Preparation of physicochemically designed beads and anionic beadsHyCellSolv pretreatment was developed for the production of cellulose beads from different wood pulps. Dissolving pulp was pretreated with acidic ethanol liquor (HyCellSolv-liquor) using different treatment times and temperatures (Figure 9). After 2 h at 75 °C the pulp was soluble in 7% NaOH-12% urea-water so that the solution was clear without undissolved fragments. Cellulose was thus dissolved in water-based solvent without undissolved fragments after HyCellSolv pretreatment.

By controlling the coagulation kinetics it was possible to physicochemically functionalize cellulose beads. A 4-6% cellulose solution was coagulated dropwise in nitric acid of different temperatures and concentrations, as well as in salt water. Physicochemical modification by controlling the coagulation kinetics provided

the beads with different pore size distributions and surface areas (Figure 10).

Beads prepared from 5% cellulose solution in 2 M HNO3 at 25 °C were oxidized by the TEMPO/NaClO2/NaClO system. The main oxidizing component (NaClO2) had a molar ratio of ~1.2 per anhydroglucose unit (AGU) of cellulose. Oxidation with the TEMPO/NaClO2/NaClO system yielded higher charge than with meta-periodate or blending with CMC and the beads were also more stable. The highest charged measured for the oxidized cellulose beads was 1848 μmol/g.

Beads as drug carriersThe applicability of cellulose beads as slow-release drug carriers was evaluated by loading the native and chemically modified beads with two model drugs, freely-soluble (riboflavin 5`-monophosphate sodium salt, lidocaine hydrochloride monohydrate) and poorly-soluble active pharmaceutical ingredients, APIs (griseofulvin and piroxicam). In addition, anionic beads were loaded with cationic drug (Ranitidine HCl). Figure 11 describes the loading


Figure 10. Effect of (A) temperature, (B) acid concentration and (C) cellulose concentration on specific surface area of the CPD cellulose beads. General coagulation conditions were: 5% cellulose solution coagulatedinto2MHNO3at25°C.

Figure 11. Unloaded and loaded drugs and their morphology.

Drug loading

Cellulose beadsin drug loading solution

Drying

Empty waterswollen beads

Dried and loaded beads

Loading and drying atroom temperature

ContentAnalysis

UV/VisSwollen CBs crushed and immersed into 10 ml water solution and stirred for 24h

FE-SEM & FTIRField emission scanning electron microscopy

NIR imaginig(SPECIM MCT based Spectral Camera)

UV/Vis- USP paddle method-0.1NHCI,@37,100RPM- 4-20 beads per vessel

Surface and Interior Morphology

Drugdistrubition

Drug releaserate studies


Solubility of drug substances

Drug substance Type of CBs Drug content (%)

Freely soluble drugs RSP Non-ionic CBs T1 12.7

T2 13.0

T3 14.3

LiHCl T1 23.2

T2 26.6

T3 27.3

Sparingly soluble drug Thp T1 3.7

T2 4.2

T3 5.0

Poorly soluble drugs PiroxicamGriseofulvin

T2 10.8

T2 22.1

Cationic drugs Ran HCl Anionic CBsNon-ionic CBs

16.1

20.1

Quinine Sulphate Anionic CBsNon-ionic CBs

3.3

11.8

Table 1. T1,T2andT3refertodifferentcellulosebeadtypeswithdifferentphysicalproperties(porosity;T3>T2>T1). CB=cellulose beads, RSP=riboflavin 5'-phosphate sodium, LiHCl=lidocaine hydrochloridemonohydrate, Thp=anhydrous theophylline, Ran HCl=ranitidine HCl.

procedure and characterization methods for the cellulose beads and presents FE-SEM pictures of unloaded and loaded beads.

Drug loading studies were performed with various different compounds and several types of CBs (different charge, porosity, etc.). Table 1 summarizes the loaded drug substances, cellulose bead types and drug loading efficacies. Drug loading is dependent on the concentration of the drug loading solution, drug choice and the properties of the beads. Table 1 shows that drug loading increased with high porosity and anionic charge of the beads (for cationic drugs).

The release of freely soluble drugs was controlled with physicochemically designed beads (Figure 12). In addition, the amount of drug release was doubled with anionic cellulose beads (Figure 13). However, therelease profile of poorly soluble APIs could not be improved with beads due to shrinkage of the beads during the drying stage.

Cationic Ranitidine hydrochlorine was used as a model drug in a study of release profiles from oxidized cellulose beads. The release profiles were noted to be constant regardless of the bead charge, ambient pH, or bead swelling rate. Compared to native cellulose beads, oxidized cellulose beads could carry twice as much drug, and the drug was observed to be in amorphous form. This property could be utilized for the delivery of poorly soluble substances. Additionally, the loaded and placebo beads demonstrated high mass uniformity, indicating a good capacity for personalized dosing of patients.

CMC-cellulose beads with a ratio of 2:8 were prepared using high DS CMC (DS 1.15-1.45). The total polymer concentration of the solution was 5%. Reference beads (5% cellulose, no CMC) and CMC-beads were loaded with three different model drugs and the release profiles of drugs and drug-polymer interactions were studied.


Figure 12. Release profile of RSP-loaded beads.

Figure 13. Cumulative release of Ranitidine HCl from non-oxidized (reference) and oxidized (20-60 °C) cellulose beads.

Anionic CMC-beads can be used to delay drug release. Also, higher amounts of poorly soluble drugs can be incorporated in anionic CMC-beads. The release profiles showed an initial “burst” release, mainly due to unbound drug, followed by a subsequent more controlled release of bound cationic drugs from anionic CMC-beads. Also poorly soluble drugs demonstrated controlled release after an initial burst. This can be explained by slow diffusion and solubility.

Cellulose beads and oxidized cellulose beads have excellent properties as drug carriers.

They demonstrated high mass uniformity and high loading capacity. Drug release was constant, regardless of environmental changes, such as pH.

Adsorption of metal ions on beadsCellulose beads contain acidic groups, which were studied by potentiometric titration. The titration data was evaluated by the FITEQL software, giving detailed information about the different acidic groups on the cellulose beads and modified cellulose beads. Modified cellulose beads had more than ten times the amount of acidic groups than cellulose beads (Figure 14).


Figure 14. Potentiometric acid titration for cellulose and cellulose derivative with acidic group.

Figure 15. Preparation of cellulose with anionic cellulose derivatives (left). Concentration of metal ions in the collected fractions as a function of elution volume for a chromatographic column filled with cellulose beads (right).

The Domsjö dissolving pulp was treated with HCl and ethanol to eliminate any lignin residue. Cellulose with 3-sulpho-2-hydroxypropylgroups was inserted during preparation of the cellulose beads. The new modified cellulose can be used as a cation exchanger, a unique characteristic that can be used to achieve better and higher sorption. In these studies, cellulose beads were used as a stationary phase in column chromatography in order to study metal ion affinities. The mechanism is mainly ion exchange by complexation of metal ions to the cellulose, which contains carboxylic groups as a functional group. It was observed that divalent ions show better sorption than monovalent ions (Figure 15).

4.2.2 Markets and business opportunities for cellulose beadsCellulose beads are porous spherical cellulose particles with diameters in the micro- to millimetre scale. Cellulose beads can be functionalized by introducing different organic or inorganic materials to the bead structure. Depending on the derivatization agent, cellulose bead properties can range from, for example, steady drug release to rapid water absorption.

There are thousands of potential applications for cellulose beads with such functionalization capacity. Cellulose beads have been commercially available for 15-20 years, but annual production volumes are very

0

2

4

6

8

10

12

14

12 17 22 27 32 37 42

pH

Volume added of NaOH (mL)

Blank

Cellulose

Cellulose deriva8ve

Iontosorb

Poten5ometric 5tria5on

Poten8ometric 8tria8ons were performed for a cellulose sample , a cellulose deriva8ve with 3-‐sulpho-‐hydroxypropyl group and a cellulose with carboxylic func8onal group (Iontosorb).

Cellulose Cellulose deriva5ve Iontosorb

lgK Concentra8on lg K Concentra8on lg K Concentra8on

2.8 112.8 2.7 94.3 3.7 750.6

4.5 6.8 5.4 17.9 4.7 538.2

6.1 2.5 9.6 45.0 8.7 25.4

total 122.1 157.2 1314.2

Table 5. Protona8on constants(lgK) and concentra8on (µeq/g) of acid groups of cellulose beads, cellulose deriva8ve and cellulose with carboxylic func8onal group.

0

2

4

6

8

10

12

14

12 17 22 27 32 37 42

pH

Volume added of NaOH (mL)

Blank

Cellulose

Cellulose deriva8ve

Iontosorb

Poten5ometric 5tria5on

Poten8ometric 8tria8ons were performed for a cellulose sample , a cellulose deriva8ve with 3-‐sulpho-‐hydroxypropyl group and a cellulose with carboxylic func8onal group (Iontosorb).

Cellulose Cellulose deriva5ve Iontosorb

lgK Concentra8on lg K Concentra8on lg K Concentra8on

2.8 112.8 2.7 94.3 3.7 750.6

4.5 6.8 5.4 17.9 4.7 538.2

6.1 2.5 9.6 45.0 8.7 25.4

total 122.1 157.2 1314.2

Table 5. Protona8on constants(lgK) and concentra8on (µeq/g) of acid groups of cellulose beads, cellulose deriva8ve and cellulose with carboxylic func8onal group.

Domsjö Cellulose

1 h to -15°C

Cellulose beads

Cellulose derivative

Preparation of cellulose beads with acidic cellulose derivatives

Cellulose

+ Urea+ NaoH+ Water

Collected in 10%HNO3

CelluloseO

OH

SO3Na

Cellulose O

O

ONa

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

5

0

0,02

0,04

0,06

0,08

0,1

0,12

0,14

0,16

0,18

0,2

40 60 80 100 120 140 160 180 200 220

C , mmol /L

V, mL

K Li Na Ba Ca Mg Sr Cd Zn Ni Mn pH

pH


Potential end uses

Chromatography Composites Acoustic boards and panels

Metal ion-exchange and water treatment

Growth medium Smart sponges

Protein immobilization Pollution recovery, e.g. oil Light-adjusting paint

Cosmetics Water damage clean up eInk Lite

Air purification Oil-water emulsion aid Bending/origami sheet

Drug loading and release Plaster Reactive textiles

Ammunition Active food packaging Cellusensors

Dietary/ nutritional supplements Mixing with CMC Cellubots

Fertilizers Absorbents Cellubricks

Feed additive Replacement of charcoal tablets Swallowable perfume

Solid-phase synthesis support

Table 2. Potential end uses for cellulose beads.

small. Cellulose beads are currently used in niche applications such as ion-exchange, chelating sorbents, dye-ligand chromatography, hydrophobic interaction, affinity chromatography, size exclusion chromatography, filter material and core-particles for pellets. In the market assessment, the objective was to identify potential end-uses for cellulose beads (both existing and novel) and to analyse which of these seemed the most favourable for commercial bead production.

The screening of possible applications was based primarily on the unique properties of cellulose beads, i.e. identifying end-uses where cellulose beads could offer significant advantages compared to competing solutions. Key properties for cellulose bead competitiveness include mechanical stability, narrow particle size distribution, high chemical resistance and compatibility with most commonly used solvents, high temperature stability, high selectivity of separation, excellent flow properties, chemical reactivity in derivatization, non-toxicity, high porosity and large surface area.

In the market assessment reference markets, key drivers, annual growth rates and competitive

advantagesofcellulosebeadsinover30potentialapplications were identified and innovated in the screening stage (Table 2). These end-uses could be divided into four main categories: consumer beads driven by business-to-consumer (B2C) markets, industrial beads driven by industrial B2B markets, chemoactive beads, which refer to laboratory-related end-uses, and “jokers”, which can represent any end-use but with a higher degree of unconventional elements. The majority of the identified bead applications were related to industrial end uses.

The identified end-uses were prioritized based on three criteria: (i) market potential (including reference market size and annual growth), (ii) margin between reference price of competing solution and estimated cellulose bead production costs, and (iii) applicability of cellulose beads in a given end-use. As a result, eight potential end uses were ranked as hitting the “sweet spot” with good market potential, adequate margin and technical applicability for the target end-use. These most interesting applications included active food packaging, solid-phase synthesis support, composites, feed additives, cosmetics, growth mediums, plaster and dietary supplements (Figure 16).


Figure 16. Eight end-uses were ranked in the “sweet spot”.

Figure 17. Preparation of novel cellulose absorbents by grafting hydrophilic monomers onto allylated cellulose fibre surface.

The majority of identified end-use opportunities were completely new applications as opposed to direct substitutes for existing products. All in all, even if the required bead properties for a specific application were achieved, cellulose beads would still represent only a niche market for the forest industry. The greatest incentive for further development therefore most likely lies outside the forest sector.

4.3 Novel absorbent materials for hygiene products

4.3.1 Preparation and application of absorbent cellulose materials

Production of novel absorbent materialsVarious novel cellulose absorbent materialswere prepared at the laboratory scale by

grafting hydrophilic monomers and/or allylated xylan to activated cellulose fibres (Figure 17) or, alternatively, by TEMPO oxidation of fibres. In addition, blends of specific materials were also evaluated. Mechanically or enzymatically pre-treated dissolving pulps and bleached never-dried softwood kraft pulps (BNDS) were mainly used as starting materials. Reaction efficiencies in cellulose activations were low, with a typical degree of substitution for allylated fibres (DSallyl) of 0.05-0.10. TEMPO oxidation was more efficient with a degree of substitution for oxidized cellulose (DSoxidized) of up to 0.2, which is close to the theoretical maximum DS. Unlike most other oxidative reactions, TEMPO oxidation is highly selective to primary alcohol groups. This decreases the maximum amount of carboxyl groups introduced to cellulose drastically; however, it also enables oxidation without disrupting the crystalline structure of cellulose (Figure 18).

Absorbent materials were freeze-dried before analysis of their capacity to absorb water and 0.9 wt-% NaCl solution. The water uptake values of the cellulose absorbent materials generally varied between 10-40 g water/g, with the highest values obtained with TEMPO-oxidized fibres, whose structure was subsequently mechanically loosened.


Figure 18. Oxidation of surface anhydroglucose units of cellulose nanofibrils by TEMPO oxidation.

Figure 19. Absorbent properties of different structures.

The mechanical loosening was a prerequisite for high water absorption capacity. Without mechanical treatment water-absorption values for TEMPO oxidized pulps were generally lower than 10 g water/g absorbent. The significant increase in water uptake capacity by light mechanical treatment is apparently due to the increase in available fibre surface. Even if the chemical composition of the absorbents would favour very high water sorption, the sorptivity would remain low if the structure of the material does not allow access of the water and swelling. The water uptake values of the grafted fibres were maximum 15 g water/g fibre. Mild mechanical

disintegration did not significantly improve the absorption capacity of the grafted materials.

Drying of absorbent fibres is crucial for preserving material performance. As freeze-drying may not be realistic at the industrial scale, the applicability of foam forming for the processing and drying of TEMPO-oxidized absorbent fibres was evaluated. The absorbent properties of different structure types are illustrated in Figure 19. Absorption capacity was lowest for paper-like structures and highest for porous and bulky freeze-dried structures.

• 100%oxidizedcellulose• Foam-laidstructure• Air-laiddrying• Filmstructure

• Softwood&oxidizedcellulose• Foam-laidstructure• Air-laiddrying• Paperstructure

• 100%oxidizedcellulose• Freeze-drying• Porousandbulkystructure

Improved (structural) absorption capasity

TEMPO

oxida,on

Glucose unit

Oxidized glucose unit


Figure 20. Free swelling absorption capacity of cellulose-based materials when processing method was varied.

In addition to drying, further processing of the material is essential, especially when considering applications using fluff pulps. In end product (e.g. nappy) manufacture, a hammer mill is used for disintegrating the cellulose. In the present small-scale studies, this process was simulated by dry blending the materials with a mixer. The results are shown in Figure 20. Absorption capacity increased in the case of foam-laid papers (target grammage 80 g/m2) when the structure was dry blended.

Novel nonwoven structuresNovel spunlaced nonwoven structures simulating commercial household wipes (50% polyester and 50% pulp) were produced in Suominen pilot line. Both air-laid and foam-forming technologies were utilized in making absorbent cellulose sheet structures. Air laying was suitable only for processing fluff pulp fibres, whereas foam forming was applicable also for the production of sheet structures from novel absorbent materials, among which TEMPO-oxidized fibres were identified as the most promising novel absorbent materials.

Foam-formed handsheets with different ratios of softwood kraft pulp and TEMPO-

oxidized pulp were prepared. The aim was to determine the optimum pulp composition for producing nonwoven base structures. The target structure needed to have as high water absorption capacity as possible. Foam-formed sheets (80 g/m2) containing 80% softwood kraft pulp fibre and 20% TEMPO-oxidized fibre were used. The foam-formed layers were combined with a polyester web by hydroentangling, targeting 50:50 blends of pulp:polyester. As a reference, a pulp:polyester composition, using tissue sheets for the pulp, was produced on the same pilot line.

The foam-formed structures provided a much stronger pulp:polyester nonwoven than the tissue-derived reference pulp. Also, the decrease in wet strength was less for the foam-formed product, even though all samples had lower wet than dry strengths. The absorption capacity was only marginally better with the foam-formed nonwoven compared to the reference. Both pulp-containing products had clearly lower absorption capacity than the 100% polyester nonwoven. The absorption capacity of the fibres does not translate directly into the absorption capacity of the nonwovens, as a lot of the absorption is attributable to the void space

Dry-‐blended

80 g/m Absortion Absortion Grammage[g/g] [g/g] [g/m2]

100% Oxidized cellulose / Consistency 0.5%Tempo oxidized cellulose 100% / Consistency 0.5% 27 100% Oxidized cellulose / Consistency 2.0%Tempo oxidized cellulose 100% / Consistency 2.0% 28 18 100% Oxidized cellulose / Second oxidation 100% Oxidized cellulose / Second oxidation Tempo oxidized cellulose 100% 450% Oxidized cellulose / 50% SoftwoodTempo oxidized cellulose 50% / Softwood 50% 16 19 8030% Oxidized cellulose / 70% SoftwoodTempo oxidized cellulose 30% / Softwood 70% 20 25 80

27 28

4

16

20 18 19

25

0 2 4 6 8

10 12 14 16 18 20 22 24 26 28 30 32 34

Tempo oxidized cellulose 100% / Consistency 0.5%

Tempo oxidized cellulose 100% / Consistency 2.0%

Tempo oxidized cellulose 100%

Tempo oxidized cellulose 50% / SoEwood 50%

Tempo oxidized cellulose 30% / SoEwood 70%

Abso

rpIo

n [g

/g]

Freeze-‐dried Air-‐laid dried; not dry blended Air-‐laid dried; dry blended

Target grammage 80 g/m2


in the nonwoven structure. The pulp-containing products make a much denser product compared to the 100% polyester nonwoven, which can be seen from the thickness of the products at a given g/m2. Clearly, it is not enough to improve the absorption of the pulp alone; in addition, the pulp needs to be in a favourable nonwoven structure.

Improved fluff pulpThe applicability of TEMPO-oxidized pulp for improving fluff pulp water absorption properties was evaluated. Besides water absorption capacity, also water retention capacity, which is highly important for many hygiene products, was characterized. Different commercial superabsorbents were used as reference materials. Foam-formed and air-dried TEMPO-oxidized handsheets were defibrated together with fluff pulp using a hammer mill. Alternatively, TEMPO-oxidized fibres were applied onto a fluff pulp web using a semi-pilot scale coating device. The oxidized cellulose containing fluff reel was also defibrated by a hammer mill before material evaluation.

The results of the gravity-based analysis of the absorption capacity of the absorbent

cellulose materials are given in Figures 21 and 22. According to the results, TEMPO-oxidized pulp did not improve the free swelling absorption capacity of fluff pulp and the material performance was not comparable with commercial superabsorbents. However, gravity-based analysis may not be the most suitable method for determining absorption capacity.

Correspondingly, the increase in absorption capacity under load was enhanced by 40% when 100% fluff was compared to 100% TEMPO. A range of different SAP grades are available, and when comparing the absorption under load of the TEMPO-based solution to the commercial bio-based SAP, the difference was only 25%, as seen in Figure 22.

The applicability of the novel fluff pulp material in a hygiene product application was demonstrated at Delipap Oy. The target was to demonstrate the potential of bio-based absorbent material – oxidized cellulose – in a product application. The reference material was conventional fluff pulp used in different kinds of hygiene products. Foam coating was used as the coating method and the Surface

Figure 21. Free swelling absorption capacity of absorbent cellulose materials.

0.9% NaCl-‐liuos

[g/g] [%] [g/g]Fluff 100% Fluff 100% 22Tempo 100% Tempo 100% -‐100 19 Fluff & Foam coating 16 g/m2 Fluff reel & Foam coated Tempo 2.5% 22 0Fluff 50% / Tempo 50% Fluff 50% / Tempo 50% 22 0Fluff 50% / SAP 50% Fluff 50% / SAP 50% 33 50Commercial SAP / Fubio Commercial SAP / Fubio 44 100Commercial SAP BASF HYSORB T7061Commercial SAP BASF HYSORB T7061 40 82 40Commercial Bio-‐based SAP Commercial Bio-‐based SAP 30 36 30

22 22 22

33

44

19

40

30

0

5

10

15

20

25

30

35

40

45

50

Fluff 100% Tempo 100% Fluff reel & Foam coated Tempo 2.5%

Fluff 50% / Tempo 50%

Fluff 50% / SAP 50%

Commercial SAP / Fubio

Commercial SAP BASF HYSORB T7061

Commercial Bio-‐based

SAP

Abso

rpJo

n [g

/g]


Figure 22.Absorptionunderload(0.3psi)ofabsorbentcellulosematerials.

Treatment Concept (Sutco) as the research environment for the manufacture of oxidized cellulose containing fluff reel. The product demonstration was carried out on Delipap’s hygiene products production line. The demonstrated bio-based absorbent material was a fluff reel containing 10% oxidized cellulose. The product demonstration was an anatomically shaped panty liner. The results of the production-scale demonstration indicated improved absorption capacity in the case of the bio-based absorbent material.

4.3.2 Techno-economic modelling of bio-based absorbentsThe objective of the modelling task was to evaluate the techno-economic feasibility of bio-based and fully biodegradable absorbent materials as replacements for fossil-based superabsorbents and to increase the use of cellulose materials in absorbent hygiene products(Figure23).

The main cost factor in bio-based absorbent production was feedstock pulp, followed by

energy and chemicals. Chemical and catalyst recycling rates and doses were the most uncertain process parameters. Successful chemical recycling could have a major impact on the production economics. The competitiveness of the studied absorbents compared to commercial superabsorbents is fully dependent on the absorption capacity, which at the time of the modelling case was inferior to commercial SAPs. The lower the absorbent capacity, the higher volumes are required. Because in the modelling scope bio-based absorbents were defined as direct substitutes for SAPs, the quantitative modelling showed poor economic feasibility.

In the qualitative opportunity assessment, the technical availability, political and health-related feasibility, as well as the bio-based absorbents’ compatibility with the forest industry value chain were all very positive, but challenges arose from the absorbent markets and technical feasibility. The technical feasibility of the recycling processes, purification and drying were still a major question mark. On a general

Absorption under load

[g/g] [%] [g/g]Fluff 100% Fluff 100% 10Tempo 100% Tempo 100% 16 60 16 Fluff & Foam coating 16 g/m2 Fluff reel & Foam coated Tempo 2.5% 14 40Fluff 50% / Tempo 50% Fluff 50% / Tempo 50% 17 70Fluff 50% / SAP 50% Fluff 50% / SAP 50% 23 130Commercial SAP / Fubio Commercial SAP / Fubio 34 240Commercial SAP BASF HYSORB T7061 Commercial SAP BASF HYSORB T7061 29 190 29Commercial Bio-‐based SAP Commercial Bio-‐based SAP 20 100 20

Fluff 100% Fluff 100% 10Tempo 100% Tempo 100% -‐100 16 Fluff & Foam coating 16 g/m2 Fluff reel & Foam coated Tempo 2.5% 14 40Fluff 50% / Tempo 50% Fluff 50% / Tempo 50% 17 70Fluff 50% / SAP 50% Fluff 50% / SAP 50% 23 130Commercial SAP / Fubio Commercial SAP / Fubio 34 240Commercial SAP BASF HYSORB T7061 Commercial SAP BASF HYSORB T7061 29 190 29Commercial Bio-‐based SAP Commercial Bio-‐based SAP 20 100 20 10

14

17

23

34

16

29

20

0

4

8

12

16

20

24

28

32

36

40

Fluff 100% Tempo 100% Fluff reel & Foam coated Tempo 2.5%

Fluff 50% / Tempo 50%

Fluff 50% / SAP 50%

Commercial SAP / Fubio

Commercial SAP BASF HYSORB T7061

Commercial Bio-‐based

SAP

AbsorpKo

n [g/g]

+ 40% + 60%

"Tempo vs. Biobased -‐ 25%"


Figure 23. Block-flow diagram of bio-based absorbent production.

level, the hygiene industry is a challenging market that is difficult to penetrate due to the dominance of a handful of strong brand owners, the large number of major absorbent producers that are developing their own bio-based absorbents, a limited willingness to pay bio-premiums in the bulk nappy market, and

difficulty in demonstrating and communicating the environmental benefits. The pros and cons of bio-based absorbents in baby nappies are summarized in Figure 24.

Figure 24. SWOT analysis of bio-based absorbents in baby nappies.


Process related

STRENGTHS •  Bio and non-‐food based raw material, increase of

bio-‐based content in nappies

•  Biodegradability •  Growing demand of all absorbent hygiene

products

•  Rela;vely simple process with high yields

WEAKNESSES •  Low absorp;on proper;es •  Overall performance s;ll unclear: absorbent

capability in absorbent core, mixing performance, bulkiness and ability to distribute liquids to prevent SAP gel blocking

•  Unknown recycling and drying process


OPPORTUNITIES

•  Increasing demand of eco-‐nappies

•  Possibili;es in other end-‐uses, especially as “improved fluff”

THREATS •  Bio-‐based SAP already entering the market

•  Development of pulpless core and other technology breakthroughs such as nanocellulose

•  Contaminants of WP3 products s;ll unclear

•  Absorp;on proper;es remain low

•  Recovery process proves to be too expensive


Figure 25. Market volume of hygiene absorbent products.

4.3.3 Markets and business opportunities for bio-based absorbentsHygiene absorbent products dominate the absorbent market. Today, over 80% of fluff pulp and over 90% of superabsorbent polymers (SAPs) are consumed in baby nappies, training pants, feminine hygiene and adult incontinence products (Figure 25). Fluff pulp can also be found in airlaid, spunlaced and other nonwovens, whereas there are numerous specialty end uses for superabsorbents, for example in agriculture, cable wraps and packaging.

Two in three mothers in the US view disposable nappies as a “necessary evil” and have expressed concerns about the environment, but not at the expense of convenience. Only a marginal consumer group uses reusable cloth nappies in the West, despite the fact that absorbent hygiene products alone make up as much as 2-3%ofallmunicipalsolidwasteinEurope1.

Overall demand for absorbent hygiene products is driven by population growth, GDP development, urbanization, ageing population, growing middle-class and increasing time pressure. For instance, in Japan, sales of adult incontinence products have already

1 Edana Sustainability Report: Baby Diapers and Incontinence

Products (2005)

exceeded sales of baby nappies. Increasing time pressure has led to the development of, for example, pull-up training pants and heavy adult incontinence products that can absorb more than five litres of liquid.

There are four key trends shaping today’s nappy development: sustainability, convenience, demand for ultra-thin products and increasing concern for product safety. Consumers have gradually started to demand more environmentally friendly products. Currently, there is a vast number of different solutions on the market including thinner, lighter and more efficient nappies with less raw materials; combinations of re-usable cloth nappies with disposable absorbent pads; nappies with bio-based materials and reduced carbon footprint; and a variety of partly biodegradable nappies. Whether the emphasis is on bio-based content or biodegradability depends strongly on the region and regional end-of-life solutions. At present, there are no 100% bio-based or biodegradable nappies on the market due to the lack of substitutes for several fossil-based components.

Almost all new hygiene product launches focus on convenience. Examples include pull-up training pants, body-conforming stretchable products, adult briefs with flexible waist belts,

Fluff pulp4.2 million tons

SAP1.5 million tons

3.4 million tons

1.4 million tons

Adult incontinence products2.0 million tons

Hygiene absorbent products8.2 million tons

To other applications 0.1 million tons

To other applications 0.8 million tons

Nappies4.6 million tons


Feminine hygiene products1.7 million tons


and light incontinence products designed for everyday use. Ultra-thin products are win-win solutions not only for consumers and brand owners, but also for retailers. These lightweight products are more comfortable, more convenient to wear, require less space, bring savings in logistic costs and reduce waste. For retailers, ultra-thin products provide reductions in valuable shelf and warehouse space.

In recent years, product safety has become a top priority in the hygiene industry. Families are concerned about, for instance, chemical safety and possible traces of contaminants. Many eco-branded products are therefore marketed as “chemical free”, “containing less chemicals”, or “certified free from harmful chemicals”. Two such chemicals commonly perceived as a possible threat or allergen are TBT (tributyl tin) and latex.

The evolution of nappy composition in Figure 26 demonstrates how the introduction of more efficient and lower cost superabsorbents has resulted in lighter nappies with enhanced performance, more superabsorbents and less fluff pulp material. A typical modern nappy has roughly the same amount of fluff pulp and SAP,

each representing about a third of the nappy weight. In the past few years, the drive towards ultra-thin products has led to a completely new nappy design, the “pulpless” nappy. Pampers Drymax nappies are one example of such a product, with an absorbent core consisting of SAP between nonwoven sheets instead of bulky fluff pulp.

The nappy value chain consists of component producers (such as fluff, SAP, nonwoven and adhesive producers), converters, brand owners and retailers. There is a great deal of horizontal integration in the value chain: many brand owners are backward integrated to convert their own products, and more and more retailers are launching their own nappy brands. There are hundreds of operators in the nappy industry, and yet innovation and product development are led by only a few multinational converter/brand owners. Two leadingbrandowners,Procter&GambleandKimberly Clark, represent together more than half of all nappy sales.

Environmentally friendly nappies are still a very small, but growing, segment. In addition to leading brand owners having their own

Figure 26. Evolution of nappy composition 1987-20112.

0

10

20

30

40

50

60

70

1987 1995 2005 2011 Average nappy composition [g/pad]

Other

Adhesives

Elastic back ear

Tape

PP

LDPE

SAP

Fluff pulp

Mass [g/nappy]

2 Modified from Edana Sustainability Report (2011)


eco-brands sold at a premium price, there are smaller players focusing on online retail with a significant market share of the eco-nappies segment. Unfortunately, “greenwashing” is a major issue in the hygiene industry, and thus all environmental claims should be supported by, for example, LCAs.

Nappy performance and absorbency are more than the sum of the individual materials. In addition to superabsorbents, each absorbent core needs other materials (typically fluff pulp) to distribute liquid into the structure and preventing gel blocking. Because water molecules are attracted to superabsorbents by electrical charges, the absorbency is strongly affected by electrolyte concentration. When salinity is the most important factor reducing the absorbency of superabsorbent polymers, pressure has a similar role to fluff pulp. Hence superabsorbent polymers are not only needed to increase nappy absorption, but also to hold the liquids under pressure.


Heterogeneous synthetic routes for producing thermomeltable cellulose esters from different pulp materials at high pulp consistencies (15-25 wt-%) were demonstrated. Etherification, which is typically carried out in aqueous conditions, would be economically attractive and industrially easy to adopt, but the experiments showed that more basic research on cellulose reactivity and synthesis development will be needed before sufficiently high degrees of substitution providing thermal melting of an end-product can be obtained. The esterification route was more efficient than etherification, and thermomeltable cellulose esters were obtained from various pre-treated and non-treated cellulose pulps. The main raw material was a dissolving pulp that can be regarded

as a significantly cheaper raw material than typical high-purity dissolving pulps (acetate-grade pulps) industrially used in cellulose ester production. The targeted properties for cellulose esters, including good film-forming abilities and melt-spinnable formulations were not fully obtained, probably due to the inhomogeneity of the materials and the hot-pressed (by static laboratory press) film structures, which always contained some visible clods. Melt extrusion of the materials was, however, successful indicating that these materials could be utilized e.g. in injection moulding processes. The degree of substitution (DS) of the materials was theoretically sufficiently high to provide completely homogeneous melts and it can be speculated that the uneven distribution of the ester substituents may be at least partly explained by the raw material quality and heterogeneous reaction conditions. The results show the importance of raw material quality in producing thermoprocessable materials.

The melt spinning studies provided new insights regarding the property requirements of novel cellulose derivatives. Melt spinning offers a more economical and efficient method compared to dry or wet spinning, which both need a polymer solvent and a solvent recovery system for the spinning line. The only main environmental impact of melt spinning is the energy required for extruder heating and running the machine.

Cellulose absorbent materials can be easily produced at kilogram scale, for example by TEMPO oxidation. The results showed that drying of chemically modified fibres is challenging when the objective is to maintain improved absorption properties. The drying process can thus be considered as a bottleneck in developing novel absorbent materials competitive with currently used superabsorbents, and the technology therefore needs further development.


The preparation of air-laid nonwovens provided new information on the requirements of the different materials (fluff pulps and SAP) and how to optimize the process parameters, and highlighted key air-laying technology development targets.

Cellulose dissolution is generally challenging and untreated pulps cannot be properly dissolved in aqueous alkaline solutions for cellulose bead production. Controlling the degree of polymerization and primary cell wall rupturing enables the use of weaker environmentally friendly solvents. Additionally, an opened structure increases the penetration of derivatizing reagents. Understanding the roles of the different factors involved in the preparation of cellulose gel-based products enables the design of cellulose beads for multiple purposes. Oxidation post-processing, blending and physicochemical design during bead coagulation are tools that can be utilized to target certain functionalities. The knowledge accumulated on process parameters and the control of basic properties enables well-established methods to be readily modified for other functionalities, such as protein/enzyme immobilization. More research is, however, required to harness the full potential of cellulose beads.

Pharmaceutical companies are increasingly using more sophisticated excipients and blends in order to defend against generic competition. Greater use of so-called functional excipients – which go beyond the traditional role of excipients as a carrier for active pharmaceutical ingredients (APIs) – is one of the key drivers for growth in the excipients market. The commercialization of cellulose beads might thus be more feasibly pursued via excipient manufacturers rather than pharmaceutical companies. Both commercialization routes should, however, be explored.


6. Networking

The research was carried out jointly by industrial and research partners. Table 3 presents theresearch partners and their roles in this topic.

Partner Role

Glocell Qvantitative economic modelling

Metsä Fibre Industrial tutor. Providing industrial view insight to techno-


Pöyry Management Consulting Market study. Economic feasibility modelling. Business potential

evaluation

Stora Enso Industrial tutor. Steering of work related to thermoplastic

celluloses, material supply. Providing industrial view insight to

techno-economic and market assessments

Suominen Industrial tutor. Preparation and testing of nonwovens, steering

of experimental work. Providing industrial view insight to techno-

economic and market assessments


Materials Science

Extrusion coating and melt spinning of thermoplastic cellulose;

mechanical processing of fibres into nonwoven structures


Organic Chemistry

Research adviser

UPM-Kymmene Industrial tutor. Development of absorbent fibre materials,

steering of experimental work related to hygiene products.

Providing industrial view insight to techno-economic and market

assessments

VTT Syntheses and testing of thermoplastic celluloses and cellulose

absorbent material

Åbo Akademi

Fibre and Cellulose Technology (FCT)

Analytical Chemistry (AC)

Pharmaceutical Sciences (PS)

FCT: Dissolution of cellulose in water-based systems, preparation

and functionalization of cellulose beads, tailoring of beads for

applications in different value chains.

PS: Beads as drug carriers

AC: Chemical analyses

Table 3. Partner organizations and their roles



Publications

Gericke, M., Trygg, J. and Fardim, P. Functional Cellulose Beads: Preparation, Characterization, and Applications, Chem. Rev. 113, 2013:4812-4836.

Trygg, J., Fardim, P., Yildir, E., Kolakovic, R. and Sandler, N. 2014. Anionic cellulose beads for drug encapsulation and release. Cellulose 21(3)2014:1945-1955.

Trygg, J., Gericke, M. and Fardim, P. 10. Functional Cellulose Microspheres, in Popa, V. (Ed.)PulpProductionandProcessing:FromPapermaking to High-Tech Products, Smithers RapraTechnology,2013.

Trygg, J., Fardim, P., Gericke, M., Mäkilä, E. and Salonen, J. Physicochemical design of the morphology and ultrastructure of cellulose beads.Carbohydr.Polym.93,2013:291-299.

Trygg, J. and Fardim, P. 2011. Enhancement of cellulose dissolution in water-based solvent via ethanol–hydrochloric acid pretreatment. Cellulose 18, 2011:987-994.

Yildir, E., Kolakovic, R., Genina, N., Trygg, J., Gericke, M., Hanski, L., Ehlers, H., Rantanen, J., Tenho, M., Vuorela, P., Fardim, P. and Sandler, N. Tailored beads made of dissolved cellulose - Investigation of their drug release properties. Int.J.Pharm.456,2013:417–423.

Presentations

Setälä, H. 2012. Novel materials based on wood polysaccharides. BiPoCon 2012 conference, May27-31,2012,Siófok,Hungary.

Setälä, H. 2012. Cellulose absorbents. FuBio Cellulose seminar, 1st October 2012, Espoo, Finland.

Posters

Rissanen, M., Wikström, L. and Lahti, J. 2012. Commercial thermoplastic celluloses in melt spinning and extrusion coating, FuBio Cellulose seminar, 1st October 2012, Espoo, Finland.

Setälä, H. 2012. The use and preparation of fibrous celluloses with 1-allyloxy-2-hydroxypropylsubstituents,3rdInternationalCelluloseconference,Nov8-13,2012,Sapporo,Japan.

Trygg, J., Kuzmanovski, G. and Fardim, P. Up-scaling of cellulose beads manufacturing. Poster presentation in FuBio seminar, August 27,2013,Espoo,Finland.

Kolakovic, R., Redant, H., Trygg, J., Gericke, M., Fardim, P. and Sandler, N. Porous cellulose beads in drug delivery – comparison of anionic and nonionic systems. Poster presentation in FuBioseminar,August27,2013,Espoo,Finland.

Arroyo, J., Trygg, J. and Fardim, P. Targeted applications of modified cellulose beads: Chromatographic column and drug release. Poster presentation in FuBio seminar, October 2012, Espoo, Finland.

Rissanen, M., Lahti, J. and Wikström, L. Thermoplastic celluloses in extrusion coating and melt spinning. Poster presentation in FuBio seminar, October 2012, Espoo, Finland.

Theses

Redant, H. Cellulose beads in drug delivery – comparison of anionic and non-ionic systems, M.Sc.Thesis,ÅboAkademiUniversity2013.

CATIONIC CELLULOSE BASED

CHEMICALS


Jonni Ahlgren, [email protected]

PA R T N E R S

Glocell

Kemira

Metsä Fibre


Stora Enso


University of Oulu

UPM-Kymmene




ABSTRACT

The high molecular weight biopolymers such as cellulose become more and more important when alternatives for synthetic polymer raw materials for water soluble chemicals are considered. Synthesis of uncharged derivatives such as hydroxyethyl cellulose and anionic derivatives such as carboxymethyl cellulose are currently used in different commercial applications e.g. as rheology modifiers and as process additives. On the other hand the products from cationic derivatives of cellulose are practically non-existent. Cellulose was used here as a raw material in the production of flocculating agents for paper and wastewater treatment applications. Cationic water-soluble polymers and cationic nano-scale particles were targeted.

It was shown that a water-soluble derivative can be made only if sufficient charge density is achieved (about DS 0.5). Three interesting reaction routes to a cationic cellulose product were identified, each of which requires further development towards commercialization.

It was shown that, in addition to dissolving pulp, also ordinary kraft pulp can be used as a raw material for polymer synthesis. Hemicelluloses need not necessarily be removed, and the cationic product quality is better if the pulp is not heat-dried before use. Softwood performed better than hardwood, although hardwood also showed good properties.

The same cationic cellulose polymer is not suitable for all applications. Sludge dewatering prefers high charge density, whereas retention and other flocculation requires high molecular weight. The cationic particle performed relatively well in both applications. The cationic cellulose derivatives as such did not perform as well as polyacrylamide in sludge dewatering or in flocculation. In flocculation under high shear and in fixing applications, however, certain cellulose derivatives exceeded the performance of the polyacrylamide reference.

Keywords:cationic cellulose, cationic particle, cellulose betainate, CST, dissolving pulp, FBRM, GTAC, kraft pulp, market analysis, never-dried kraft pulp, techno-economic modelling


1. Work background

Cationic flocculating polymers have an important role in many industrial and municipal applications, such as in papermaking as a retention aid, in different wastewater treatments as a flocculant, and in sludge dewatering. Increasing environmental concern limits the use of synthetic cationic flocculating polymers, and alternatives to them are needed. One good option for this is cellulose.

Wood cellulose has one of the highest molecular weights of all natural polymers, i.e. biopolymers. Cellulose is also widely available, being the most abundant annually renewable biomass on the planet. Cellulose also has an important role in many industrial processes, such as paper- and boardmaking and fibre production.

Cellulose in its raw state is not water soluble and has no cationic charge and thus requires modification before it can be used as a cationic flocculating polymer.

Cellulose derivatization to water-soluble products has long been known. Uncharged water-soluble derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose and methyl cellulose, and anionically charged derivatives such as carboxymethyl cellulose are used widely in different applications, for example, as rheology modifiers and process additives. Cationic derivatives are much less known, and their commercial utilization is currently negligible.

The cationic polymer market is worth close to $4 billion, with global production (excluding starch in papermaking) at around 1 million tonnes a year.

It has been previously proven that cellulose can be made water soluble by introducing either non-ionic or anionic polar groups. If cationic groups could also be introduced to the cellulose

molecule, water solubility would be achieved and its use as a flocculating polymer would become possible.

This has been demonstrated in the TEKES project, Novel Cellulose Chemicals in Papermaking – CelPlus, where cationic water-soluble derivatives were made from cellulose. The derivatives were also tested in papermaking applications such as retention, dewatering and pitch control. Optimization of the manufacturing process was not included in the scope of CelPlus. Thus, identification of the optimum manufacturing method and its optimization were the main goals of the current research.

Although the main goal was to obtain a water-soluble cationic cellulose derivative, this approach was also questioned. An alternative approach involving the production of a cationic derivative of nano-scale cellulosic particles was investigated to determine whether an efficient cationic flocculant needs to be a water-soluble polymer. Both approaches were tested in different applications at laboratory scale.

The economic feasibility of the selected processes was also evaluated in order to compare how successful the cellulose derivatives would be commercially compared to synthetic cationic polymers.


2. Objectives

A new process for producing a cationized, water-soluble, cellulose-based polyelectrolyte chemical product was to be developed, verified at initial pilot scale and modelled economically. The polymeric product was to be tested and benchmarked in selected applications as a paper and/or water processing chemical.

Cationized cellulose nano-scale particles were also to be developed in order to compare them to water-soluble derivatives.


The research was divided into five Tasks:• Activationandmolecularweightcontrol• Evaluationofroutesforwater-soluble

cationic cellulose• Developmentofroutesforwater-soluble

cationic cellulose• Cationicparticlesfromreactivemilling• Applicationtesting

In ‘Activation and molecular weight control’ the aim was to improve the reactivity of wood pulp cellulose. In ‘Evaluation of routes for water-soluble cationic cellulose’ the aim was to evaluate different routes for synthesizing cationic cellulose derivatives for flocculants. In ‘Development of routes for water-soluble cationic cellulose’ the objective was to identify the two most potential synthesis routes and optimize them with the aim of upscaling one of the routes to the pilot scale. ‘Cationic particles from reactive milling’ was devoted to cationic nano-scale particle synthesis. Most of the product characterization work of the samples and application testing were done in ‘Application testing’.

4. Results

4.1 Used pulps

Different native and pretreated cellulosic pulps were used as starting material during the research. The aim was to find a pulp for chemical synthesis having high reactivity and resulting in a cationic polymeric end product of as high as possible molecular weight. In the cationic nano-scale particles the molecular weight of the cellulose did not play as important a role.

The used pulps and some of their properties are listed in Table 1.

4.2 Activation

The aim of the activation research was to investigate means of improving the chemical reactivity of cellulose and to evaluate how the improved activation leading to reactivity improvement could best be characterized. For the latter, the most straightforward method was considered to be a chemical derivatization itself.

As a model derivatization reaction, a simple carboxymethylation using sodium monochloroacetate, CMC synthesis, was selected. Using this method it was concluded that there was no significant difference in reactivity whether the cellulose was disintegrated in dry or wet form, and that isopropanol was the best performing additive in the reaction media.

Different energy sources during the pulp activation and CMC reaction stages were also studied. Use of microwaves gave a better reaction result than conventional heating, whereas reaction with ultrawaves performed the worst. Three different heating techniques, conventional heating, microwaves and ultrasound, were thereafter used for CMC reaction with Borregaard and Domsjö dissolving pulp. There was no clear


Cellulose starting material Abbreviation Mw (kDa)

Bahia dissolving pulp Bahia 360

Blue Bear Ultra Ether, Borregaard dissolving pulp Borregaard 1700

Domsjö dissolving pulp after mechanical treatment Domsjö 410

Domsjö dissolving pulp after acetylation DAc 550

Domsjö dissolving pulp after standard Biocelsol mechanical and enzyma-tic pre-treatment (see Chapter “Water based dissolution and regeneration processes”)

DENz nd

Domsjö dissolving pulp after novel mechanical and enzymatic treatment (advanced Biocelsol pre-treatment, see Chapter “Water based dissolution and regeneration processes”)

Dext 160

Enoalfa, Enocell dissolving pulp, Stora Enso Enoalfa nd

Bleached birch kraft pulp, Kaskinen Birch nd

Never-dried hemi-poor hardwood kraft pulp (birch) – freeze dried before use HWNDHP nd

Never-dried softwood kraft pulp (hemicelluloses not removed) – freeze dried before use

SWND nd

Never-dried hemi-poor softwood kraft pulp – freeze dried before use when used in DMAc/LiCl or HC DIT reaction systems

SWNDHP 880

Acetylated softwood never-dried hemi-poor kraft pulp Ac-SWNDHP nd

Butylated softwood never-dried hemi-poor kraft pulp B-SWNDHP nd

Thermomechanical pulp TMP nd

Microcrystalline cellulose MCC nd

Methylated cellulose MeC nd

Micro- and nanofibrillated cellulose MFC nd

Sigma α-cellulose 670

Table 1. Used cellulose and cellulose pulps. nd=not determined.

difference between the reactivity of the two dissolving pulps despite their different origin and cellulose degree of polymerization (DP) when the same energy source was used.

Different activation parameters were further studied using the actual cationization, GTAC synthesis (see Figure 1). Of the energy sources studied, microwaves gave again the best reaction results. Disintegration, especially wet disintegration, had a higher effect on GTAC than CMC reaction. It was also shown that CMC and GTAC synthesis have different NaOH concentration optimums. No better additive than isopropanol was found.

Chemical pre-treatment methods, such as acetylation, hydroxypropylation or methylation, did not give satisfactory results in increasing the reactivity of cellulose in cationization. Moreover, methylation seemed to disturb the cationization reaction, probably due to competing for the same active hydroxyl sites. It was considered that in certain cases hydroxypropylation could help improve solubility if it is done after the cationization step.

Freezing of alkaline water treated cellulose to -40 °C with and without ZnO as an additive was also tested as a pre-treatment method, but was not found to improve cationization.


Figure 1. The first six selected preparation methods for cationized cellulose derivatives: (1) Williamson etherification, (2)glycidyl route (GTAC), (3)Mannich routes, (4)C6activation, (5)Michael route,and (6)grafting methods.

Reaction route Utilized for pulps

Cellulose betainate Borregaard, Domsjö, Bahia

Cationizationofcelluloseacrylatewith3-methylimidazoliumpropionatechloride Borregaard, Domsjö

Cationization of cellulose acrylate with diethylamine Borregaard

Cationization of cellulose 2-methylpropanoyl bromide with 1-methylimidazole Borregaard

Cationization of low DS nitrocellulose Borregaard

Mannich reactions with cellulose carbamate Domsjö

Cellulose esterification with aromatic, tertiary amine group containing acid

halide and its quaternization with methyl iodide

Table 2. Some homogenous system reaction routes.

4.3 Water-soluble derivatives

4.3.1 Reaction route screeningIn the first phase several alternative reaction routes to cationic, water-soluble cellulose derivatives were screened. Figure 1 and Table 2 summarize the approaches tested.

The GTAC method was studied in several reaction systems, both in homogeneous and heterogeneous systems, and their reaction efficiencies were compared. The

other cationizations were made only in the homogeneous systems. Table 3 lists the usedreaction systems.

The reaction routes with highest potential were GTAC modification in a DMAc/LiCl homogenous system and in a HC DIT heterogeneous system, cationization of cellulose acrylate, and cationization of cellulose betainate. These reaction routes were further optimized.


Abbreviation Reaction system

Aq Aqueous system with cosolvent (typically 10-50% cosolvent) and 5-8 wt-% of cellulose (het-

erogeneous). With GTAC.

Biocelsol 5.5%NaOH/1.3%ZnO(homogeneous),5-8wt-%ofcellulose.WithGTAC.

DMAc/LiCl System with 5% lithium chloride in dimethylacetamide. Typically 1-5 wt-% of cellulose depending

on the cellulose type was dissolved in DMAc/LiCl yielding a homogeneous solution. With GTAC.

HC DIT High-consistency DIT or other reactor system typically with 20-70 wt-% of cellulose (hetero-

geneous) without any cosolvents. With GTAC.

two-phase E.g. water-toluene (heterogeneous) with 2-15 wt-% of cellulose. With GTAC.

MIPCl Cationizationofcelluloseacrylatewith3-methylimidazoliumpropionatechloride

NClB Cellulose betainate (N-chloro-betainate)

Other UH The other routes studied.

Table 3. Used reaction systems for water-soluble derivatives.

4.3.2 Reaction efficiency of the GTAC routesReaction efficiencies were calculated from reacted GTAC amount, and they were evaluated for different GTAC routes. The results are shown in Figure 2, where the calculated reaction efficiencies are plotted against the DS achieved. The plot forms three straight lines when the dominating factor is the used GTAC amount. This is seen in Figure 3, where the parameter‘Reaction efficiency per DS’ is plotted against the used GTAC amount. The best reaction efficiencies were obtained with the HC DIT route, thus in high consistency systems. When the best reaction efficiencies from Figure 2 are plotted against the achieved DS, the relationship between achievable reaction efficiency and DS is obtained (Figure 4).

There is a clear correlation between high DS and good reaction efficiency. It seems, however, that with the reaction systems used it is difficult to reach over 50% reaction efficiency. If a large amount of GTAC reactant is lost, which is the case when the reaction efficiency is below 50%, the manufacturing costs are high, making GTAC cationization uneconomical. Thus, means of achieving a higher GTAC utilization rate need to be studied further.


Figure 2. Reaction efficiency calculated from reacted GTAC against achieved DS. Classified by reaction system (a) and cellulose type (b).

a)

b)

0

10

20

30

40

50

60

0,0 0,5 1,0 1,5 2,0

Reac%o

n effi

cien

cy (R

E), %

DS

Aq

Biocelsol

DMAc/LiCl

HC DIT

two-‐phase

0

10

20

30

40

50

60

0,0 0,5 1,0 1,5 2,0

Reac%o

n effi

cien

cy (R

E), %

DS

Borregaard

Domsjö

DAc

DENz

Dext

SWNDHP

HWNDHP

SWND

Enoalfa

Ac-‐SWNDHP

MeC

B-‐SWNDHP

MCC


Figure 4. The best achieved reaction efficiencies against the DS values achieved (based on maximum points from Figure 2).

35

40

45

50

55

60

0,9 1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9

Max

reac

(on

efficien

cy (R

E) b

ased

on

GTAC

, %

DS achieved

Figure 3. Parameter ‘Reaction efficiency per DS’ against used GTAC amount.

0

20

40

60

80

100

120

140

0,0 1,0 2,0 3,0 4,0 5,0 6,0

Reac

%on effi

cien

cy RE pe

r DS ac

hiev

ed

GTAC used, mol/AGU

Aq

Biocelsol

DMAc/LiCl

HC DIT

two-‐phase


Figure 5. Charge density at pH 4 against DS. Classified by reaction system (a) and by cellulose type (b).

4.3.3 Sample characterizationFor flocculating polymers, the key parameters are:

• Solubility• Molecularweight(chainlength)• Chargedensity

The solubility of the cationic cellulose derivatives was characterized by measuring the turbidity of a 1% polymer solution. The effect of polymer chain length was characterized by measuring the viscosity of a 2% polymer solution. Because the polyelectrolyte charge affects the solution viscosity, salt viscosity was used as the main parameter to describe the effect of molecular weight. The charge density of the polymer was characterized by polyelectrolyte titration at pH's 4 and 7.5. The charge density

measured at lower pH was mostly used in the evaluations because the ester derivatives did not give reliable results due to decomposition by hydrolysis at higher pH.

In the results, samples are classified based on both the reaction route used and the cellulose starting material.

Figure 5 shows the relationship between measured DS and measured charge density at pH 4. The charge density of most of the derivatives is lower than expected based on the DS values. In some cases the charge density is, however, higher than expected, especially with some of the DMAc/LiCl samples. The DS of the samples was measured partly based on sample nitrogen content and partly by using

a)

b)

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

0,0 0,5 1,0 1,5 2,0

Charge den

sity at p

H 4, m

eq/g

DS

Aq

Biocelsol

DMAc/LiCl

HC DIT

two-‐phase

MIPCl

NClB

Other UH

theoreEcal

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

0,0 0,5 1,0 1,5 2,0

Charge den

sity at p

H 4, m

eq/g

DS

Borregaard

Domsjö

DAc

DENz

Dext

SWNDHP

HWNDHP

SWND

Enoalfa

Ac-‐SWNDHP

MeC

Bahia

theoreHcal


NMR. Further investigation is clearly required in order to clarify the relationship between DS and charge density.

The solubility behaviour of the samples is presented in Figure 6. Polymer solubility improves and thus solution turbidity decreases with increasing charge density. There is no exact definition of good solubility, but, for example, when targeting solutions with turbidity lower than 100 NTU, a charge density of 2 meq/g of polymer or higher is required. No significant difference between the reaction systems or cellulose types is found, although the HC DIT reaction system seems to give somewhat lower and cellulose betainate (NClB) and 3-methylimidazolium propionatechloride (MIPCl) somewhat higher solubility

compared to the majority of the samples. The highest charge densities were achieved using the DMAc/LiCl reaction system and Domsjö or extruded Domsjö (Dext) pulps.

The highest viscosities were achieved using cellulose betainate, 3-methylimidazoliumpropionate chloride (MIPCl), HC DIT or DMAc/LiCl reaction routes, and Borregaard pulp, SWNDHP or Domsjö pulp (Figure 7). When the salt viscosity correlating with polymer chain length is plotted against its charge density in the area of proper solubility (charge density >2 meq/g), the figure reveals a clear trend of reducing viscosity with higher charge density (Figure 7). This indicates that a very high molecular weight product with very high charge density cannot be obtained.

Figure 6. Turbidity against charge density at pH 4. Classified by reaction system (a) and by cellulose type (b).

a)

b)

1

10

100

1000

10000

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0

Turbidity

at 1

%, N

TU

Charge density at pH 4, meq/g

Aq

DMAc/LiCl

HC DIT

two-‐phase

MIPCl

NClB

Other UH

1

10

100

1000

10000

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0

Turbidity

at 1

%, N

TU


Borregaard Domsjö DAc Dext SWNDHP HWNDHP SWND Enoalfa Ac-‐SWNDHP MeC Bahia


Figure 7. Salt viscosity vs. charge density, when charge density is >2 meq/g. Classified by reaction system (a) and by cellulose type (b).

4.4 Cationic particles

Two main cationization routes were used to produce cationic nano-scale particles, see Table 4.

Cationization was tested both before and after cellulose comminution. Comminution after cellulose cationization was considered to be better. In addition, commercial microfibrillated and nanofibrillated celluloses were tested in cationization.

The main problem with the cationic nano-

scale particles was the product suspension concentration, which remained <0.5% after the comminution stage in a high intensity homogenizer.

Concentration of the suspension was also tested, and promising results were obtained by concentratingthesuspensionto30-100%withno significant loss in performance efficiency. It was also found that drying without performance loss can be achieved if the particles have a higher charge density.

a)

b)

1

10

100

1000

10000

2,0 2,5 3,0 3,5 4,0 4,5

Salt viscosity

at 2

%, m

Pas


Aq

Biocelsol

DMAc/LiCl

HC DIT

two-‐phase

MIPCl

NClB

Other UH

1

10

100

1000

10000

2,0 2,5 3,0 3,5 4,0 4,5

Salt viscosity

at 2

%, m

Pas


Borregaard Domsjö DAc DENz Dext SWNDHP HWNDHP SWND Enoalfa Ac-‐SWNDHP MeC Bahia


4.5 Performance evaluation

Product performance was evaluated using laboratory-scale methods. Sludge dewatering was tested using a CST (capillary suction time) method where the speed of water drainage from a sludge into a standardized piece of board is measured; the shorter the drainage time, the better the dewatering capacity. Flocculation efficiency, describing, for example, retention on the paper machine, was tested using the FBRM (focused beam reflectance measurement) method, which detects the particle or floc size of the suspension dynamically, with shear forces induced in the suspension controlled by mixing speed and time of mixing; the bigger floc size, the better the flocculation efficiency. Pitch control by fixing was tested by measuring how much turbidity in a mechanical pulp suspension water is removed by adding the fixing agent; the higher the removal percentage, the better the fixing performance.

The relationship between CST time and charge density of the sample is shown in Figure 8, which clearly reveals charge density to be the dominating factor in CST performance. The best performing samples are those with the highest charge density.

Some additional conclusions can also be drawn. Certain products, such as the cationic nano-scale particles and derivatives made via the methylimidazolium propionate chloride (MIPCl)

route, perform better in sludge dewatering than expected based on their charge density. On the other hand, the HC DIT made samples seem to perform worse than expected based on their charge density. One possible explanation for this is that because the HC DIT route is a heterogeneous system, the charge created during the modification is not evenly distributed. In addition, pulp type was found to have less of an impact on performance than expected; the Dext and Domsjö pulps were among the best performers with the DMAc/LiCl route, but well-performing samples were also made using Borregaard pulp. None of the cellulose derivatives had as good performance in CST as the reference polyacryl-amide, although their performance was not far from the reference (Figure 8). There are indications that sludge dewatering performance of the derivatives improves with higher molecular weight, but this requires further confirmation.

Typical FBRM curves are presented in Figure 9. When a flocculant is dosed, the floc size increases rapidly. When shearing is induced, i.e. mixing is continued, the floc size starts to decrease. With some cellulose derivatives it was found that even though the initial floc size was not as big as the reference, the decrease in floc size due to shearing was not as severe as the reference. Moreover, after a certain shearing level the floc size of the cellulose derivative was larger than with the reference (Figure 9).

Abbreviation Reaction system Maximum charge density achieved at pH 4, meq/g

AminoG Periodate oxidation of cellulose to

dialdehyde cellulose and subsequent

cationization using aminoguanidine

hydrochloride

2.3

Girard’s T Periodate oxidation of cellulose to

dialdehyde cellulose and subsequent

cationization using Girard’s reagent T

1.2

Table 4. Cationic particle reaction systems and achieved charge densities.


Figure 8. CST times vs. charge density at 8 kg/t dosage. Classified by reaction system (a) and by cellulose type (b). Reference polyacrylamide, Fennopol K506, gave a typical CST time of <10 s at 6-8 kg/t dosage. The sludge is a municipal digested sludge, pH 7-7.5 (all CST tests). Tests were performed at different times using different sludges from the same source.

a)

b)

0

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220

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260

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0

CST %m

e at 8 kg/t, s


Aq

Biocelsol

DMAc/LiCl

HC DIT

two-‐phase

MIPCl

NClB

Other UH

AminoG

Girard's T

0

20

40

60

80

100

120

140

160

180

200

220

240

260

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0

CST %m

e at 8 kg/t, s


Borregaard

Domsjö

DAc

DENz

Dext

SWNDHP

HWNDHP

SWND

Enoalfa

Ac-‐SWNDHP

Bahia

Birch (Kaskinen) MFC


Figure 9.CurvesmeasuredusingtheFBRMmethod.FennopolK3400Risthepolyacrylamidereference.UH-FBC-WP4-I is a sample made from Borregaard pulp using the cellulose betainate route. Dosing as kg active / t dry. See other details in Figure 10.

The dependence of flocculating efficiency on salt viscosity remains an anomaly, see Figure 10. In some cases high salt viscosity of the product clearly gave better flocculation efficiency. This was the case for samples made using cellulose betainate (NClB), MIPCl or HC DIT reaction systems and mostly Borregaard, SWNDHP or Enoalfa pulps. However, the same pulps also resulted in samples that did not show good flocculating efficiency despite having high salt viscosity. The reason for this odd behaviour is still unclear. The cationic particles also performed well in the flocculation tests. The better performing cationic particle, made using the aminoguanidine route, gave a maximum mean floc size of 24-27 μm at 12 kg/t dosage.

The cationic particles had an odd effect on floc strength, see Figure 11. Floc size increase was minimal, but shear resistance was high, even

increasing with higher shear levels. In high shearing systems the cationic particle thus gave as good, or even better, final flocculation efficiency than the reference polyacrylamide.

The fixing performance of selected samples is presented in Figure 12. While some samples performed better than the reference, worse performance was found in many cases. The cationic nano-scale particles performed clearly worse in fixing than many other samples. Some properties of the samples used in the fixing tests are presented in Table 5. The best performing samples in the fixing tests clearly belong to the group with the highest charge densities. Interestingly, the fixing performance of many of the cellulose derivatives with a clearly lower charge density than the reference was comparable or better than that of the polyamine reference having a charge density of about 7 meq/g.

10

15

20

25

30

35

40

45

50

15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

Mean flo

c size, µ

m

Mixing 1me, s

Fennopol K3400R_4kg/t

UH-‐FBC-‐WP4-‐I_12kg/t

UH-‐FBC-‐WP4-‐I_8kg/t

UH-‐FBC-‐WP4-‐I 4 kg/t


Figure 10. Maximum mean floc sizes at dosing 12 kg/t from the FBRM experiments against salt viscosity. Classified by reaction system (a) and by cellulose type (b). Tests were made at different times using the same type of mechanical pulp from two different sources. Furnish suspension: 60% groundwood, 40% PCC, pH 7.5, mixing speed 1500 rpm (all FBRM tests).

a) 10

15

20

25

30

35

1 10 100 1000 10000

Max m

ean flo

c size at 1

2 kg/t, µ

m

Salt viscosity at 2 %, mPas

Aq

Biocelsol

DMAc/LiCl

HC DIT

two-‐phase

MIPCl

NClB

Other UH

b) 10

15

20

25

30

35

1 10 100 1000 10000

Max m

ean flo

c size at 1

2 kg/t, µ

m

Salt viscosity at 2 %, mPas

Borregaard Domsjö DAc DENz Dext SWNDHP HWNDHP SWND Enoalfa Ac-‐SWNDHP Bahia


Figure 12. Fixing performance of selected samples. Groundwood pulp, pH 6.9. Dosing as g active / t dry pulp. Polyamine is the reference polymer.

20

30

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50

60

70

80

90

100

600 800 1000 1200 1400 1600 1800 2000

Turbidity

removal (%

)

Dosing, g/t

VTT-‐312

VTT-‐311

UH-‐FBC-‐WP4-‐VII UH-‐1-‐1

Polyamine

VTT-‐313

VTT-‐320

UH-‐FBC-‐WP4-‐VI AGDAC11

Groundwood pulp

Figure 11.CurvesmeasuredusingtheFBRMmethod.FennopolK3400Risthepolyacrylamidereference.AGDAC11 is a cationic nano-scale particle sample.

10

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50

15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

Mean flo

c size, µ

m

Mixing 1me, s

Fennopol K3400R 4 kg/t

AGDAC11_4 kg/t

AGDAC11_17 kg/t


4.6 Summary of the results

• Thebestpulpactivationmethodfoundwaswet disintegration. Chemical pre-treatment or freezing did not increase pulp reactivity. Use of microwaves during the activation and reaction stages gave better results than conventional heating.

• Thebestreactionroutesidentifiedforcationization were GTAC synthesis, the cellulose betainate route, and cationic particles. All three routes have their benefits and limitations, but none of them alone result in sufficient cationization.

• High-consistencyreactionsystemswerethebest systems identified.

• Goodsolubilityofacationiccellulosederivative requires a charge density of about 2 meq/g (DS about 0.5).

• Whenthechargedensityofthecationicend product is higher, the molecular weight tends to be lower.

• Differentapplicationsrequiredifferentpolymer properties.

• Sludgedewateringperformance(CST): - Prefers high charge density, except with

cationic particles - Best reaction systems: MIPCl and other

Michael routes, NClB and cationic particles - Best starting celluloses: no significant

differences, only SWNDHP gave poorer results

• Flocculationperformance(FBRM): - Prefers high molecular weight, except

with cationic particles where cellulose DP is irrelevant

- Best reaction systems: NClB, HC DIT, MIPCl and other Michael routes, cationic particles

- Best starting celluloses: Borregaard, SWNDHP and Enoalfa

- Cellulose derivatives did not give as big floc size as the reference polyacrylamide, but flocs were more shear resistant

• Inpitchcontrolbyfixing,somederivativesperformed better than the reference.

• Normalkraftpulpcanbeused,hemicelluloses have no significant effect on performance.

Table 5. Some properties of the samples mentioned in the figures above. Nd=not determined.

Code Cellulose Reaction system

Viscosity 2%, mPas

Salt viscosity 2%, mPas

Turbidity 1% (NTU)

Charge pH 4 meq/g

AGDAC11 Birch (Kaskinen)

Amino-guanidine

nd nd nd 2.3

UH-1-1 Domsjö NClB 394 nd 4 1.9

UH-FBC-WP4-I Borregaard NClB 55000 4515 18 2.6

UH-FBC-WP4-VI Domsjö MIPCl 21 11 10 3.5

UH-FBC-WP4-VII Bahia NClB 48 31 4 3.6

VTT-311 Dext DMAc/LiCl, GTAC

25 16 11 4.4


22 14 15 4.3


85 38 31 3.1

VTT-320 Domsjö DMAc/LiCl, GTAC

66 34 22 4.5


4.7 Markets and business opportunities for cationic water-soluble cellulose

About 20% of water-soluble polymers bear a cationic charge, while the remaining 80% consist of anionic and neutral polymers. Key properties of cationic polymers are molecular weight and charge density, which vary significantly depending on the end-use application. The cationic cellulose developed in the FuBio Cellulose programme has a molecular weight and charge density suitable for coagulation and flocculation applications. The key end-use sectors for cationic cellulose therefore include the water treatment, pulp and paper, oil, mining, cosmetics and textile industries.

The most widely used cationic polymer is polyacrylamide (PAM), followed by quaternary ammonium polymers and polyamines. Less than 10% of cationic polymers are currently based on natural materials such as chitosan. Large-scale manufacturers of bio-based cationic chemicals are currently few in number, but there is significant research interest in this area. Because the FuBio Cellulose products were developed specifically as coagulants and flocculants, other potential water-soluble polymers, such as cationic starch, were excluded from the market analysis.

Water treatment and pulp and paper are the largest end-use markets, which together account for over 80% of annual cationic polymer consumption. Key applications in these sectors include coagulation and flocculation in raw water and wastewater treatment, sludge dewatering, and retention aid in pulp and paper processes. Different applications require different polymer properties. For example, sludge dewatering requires a high molecular weight with linear, branched or cross-linked structures, whereas coagulant polymers have much lower molecular weight but very high cationic charge.

Demand for cationic water-soluble cellulose in water treatment applications is driven by limited water availability, changes in water use, increasing quality requirements, types of pollutants, trade-offs between various chemical compounds, government policies, and the emerging bio-based economy. Water scarcity is the key driver behind all water-related businesses and has driven both public and private sectors to focus on water recycling, reutilization and minimization of discharge water – all of which increase the demand for water treatment chemicals.

Geographical location, seasons, and water end-use have a major impact on the type and amount of coagulants and flocculants required. Demand for cationic polymers, in particular, is growing alongside increasing energy and resource efficiency targets. Municipal and many industrial wastewaters bearing impurities with high anionic charge can be effectively neutralized with cationic flocculants. The required molecular weight and charge density of the applied cationic polymer depends on the types of pollutants contained in the wastewater. Selecting the optimum coagulant and flocculant combination includes trade-offs among various chemicals. For instance, the ratio of metal salts to cationic polymers, or the ratio between different cationics may be altered based on chemical price changes to optimize overall cost efficiency. In most applications, the right coagulant and flocculant combination needs to be confirmed by on-site sedimentation tests.

Government policies also have a strong influence on the demand development of cationic polymers. Dosage volumes depend on the required purity levels (e.g. COD, BOD5 and phosphorus), which vary in different administrative regions. There are planned legislative restrictions for cationic polymers in Spain, Germany and Sweden driven by monomer residues, biodegradability and sustainability,


Figure 13. Potential of cationic cellulose in cosmetics and pulp and paper applications.

Market sizeGrowth potential ofthe end‐use segment

Growth potential

Unit value

Capability andwillingnessto pay

Regulativerestrictions

Legislativeenvironment of theend‐use segment

Threat of newtechnologies

Threat of subsitutionchemicals

Technical substitutionpotential

Market sizeGrowth potential ofthe end‐use segment

Growth potential

Unit value

Capability andwillingnessto pay

Regulativerestrictions

Legislativeenvironment of theend‐use segment

Threat of newtechnologies

Threat of subsitutionchemicals

Technical substitutionpotential

Cosmetics Pulp & Paper


respectively. These restrictions would limit or even ban the use of the most common cationic polymer, c-PAM, and thus, could open new opportunities for cationic cellulose. In addition, any actions supporting the creation of a bio-based economy will support the adoption of alternative bio-based materials.

In order to identify the potential of cationic cellulose in different end-use sectors, a variety of factors were analysed, including market size, growth of the end-use segment, growth of cationic chemical use in that segment, unit value, and capability and willingness to pay for bio-based or biodegradable products. However, the most crucial factors affecting the potential for cationic cellulose were the technical substitution potential, unit value and regulatory environment.

According to the analysis, cosmetic applications seemed the most promising end-use for cellulose-based cationic chemicals. Although the market size of cationic chemicals in cosmetics is small, both the cosmetic industry and the cationic chemicals used in hair care products (mainly polyquaternium) are estimated to grow at a respectable rate of over 3% per annum. There is a clear demand forbio-based raw materials in cosmetic products and the industry has both the capability and willingness to pay a premium for specific products. However, the product cycle in

cosmetics is short and polymer quantities small. Cosmetic applications do not require very high molecular weight or high cationic charge, and therefore the technical substitution potential of cationic cellulose is very high.

The pulp and paper industry was also an interesting end-use for cationic cellulose. Pulp and paper production is the second largest market for cationic chemicals in general. Both the end-use market and the use of cationic chemicals are slightly growing, although mostly in emerging markets. The key factors determining the potential of cationic cellulose in cosmetics and pulp and paper applications aresummarizedinFigure13.

4.8 Techno-economic modelling of cationic cellulose

The techno-economic analysis examined the production of cationic water-soluble cellulose production for water purification applications. The process concept of carboxymethylcellulose (CMC) was used as a general reference for the cationic cellulose process concept. Five different process variations were evaluated: (i) aqueous media with GTAC as reagent, (ii) organic media with GTAC as reagent, (iii) reactive dissolving with chloro-betainyl chloride as reagent, (iv) DMAc-LiCl as organic media and (v) a high-consistency process. Figure 14 shows a block-flow diagram of the studied process concept.


Based on the techno-economic analyses, the high-consistency process seems to be the most promising of the five concepts. The cationic derivatization agent GTAC was the biggest production cost factor and thus had a major impact on the economic feasibility. As a result, further research should focus on reducing GTAC consumption either by increasing reaction efficiency or by improving chemical recovery and recycling.

Cationic water-soluble polymers are performance chemicals, and their performance thus defines their potential selling price. Product functionality and application testing should be a top priority of future research and product development. Monomer residues, biodegradability and sustainability are the key driving forces behind planned legislative restrictions on cationic polymers in Spain, Germany and Sweden, respectively. Product development should also focus on exploiting these unique opportunities for cationic cellulose. The strengths and weaknesses of cationic

Figure 14. Block-flow diagram of cationic water-soluble cellulose production.

NaOHwater

DMAcLiCi

GTAC

HCI

Cellulose

Basification

Cationization

Neutralization

Filtration

Washing

Cationic cellulose

IPA

Drying

Solvent recovery

water-soluble cellulose in water treatment applications are summarized in a SWOT analysis in Figure 15.


Use of cellulose pulp as a raw material for the production of cationic flocculants was shown to have good potential for industrial utilization. The ready availability of cellulose, as the largest annually renewable biomass on the planet, further underscores the potential of this raw material.

Cellulose derivatives are normally produced using a dissolving pulp. The present study, however, showed that normal kraft pulp can be used irrespective of hemicellulose removal; only a minimal impact on final product performance was observed when hemicelluloses were not removed. This is a key finding, as it affects the raw material price remarkably.

A major impact on end product properties was found if the starting cellulose raw material was not heat dried before use. This calls for integrating cationic derivatization of cellulose close to pulp manufacturing. Although never-dried pulp performed better, normal heat-dried pulp can also be used.

The preferred pulp is softwood. Hardwood pulp gives a higher molecular weight end product, but reacts less readily. The hemicellulose content of hardwood is also higher than that of softwood.

Although the majority of the present findings require further confirmation, the results at this stage are very promising.

Several potential reaction types could be developed, although none of them can be utilized directly.


GTAC synthesis lacks reaction efficiency, which increases reactant consumption and thus manufacturing costs. The best reaction efficiency achieved was 55%, and any significant further increase on this is considered unlikely. One means of making the GTAC route more viable is to find a way to regenerate and circulate the extra reactant. This offers a very interesting avenue for further research.

The GTAC synthesis results show how important the processing consistency or concentration is during the reaction. The more solvents or other media that are needed, the higher the recycling costs. Low processing concentration is the weakest link in the cellulose betainate route developed. The end product properties were good, but the processing cost became high due to too low concentration during processing. The process economics would be dramatically improved if the processing could be done in a high concentration system, such as in an extruder, kneader or such. This requires further study, with a focus on high viscous processing. Uncertainties also remained regarding the

cellulose betainate product, namely the stability of the dry product and, because they are esters, the need for special attention in the application systems. Thus, further development of cellulose betainate is also required.

The third promising technique found is the use of nano-sized cationic particles. The particles performed comparably to soluble polymers and, in some cases, even better. However, the studied route has two weak aspects. One is cationization through the aldehyde oxidation route, which presents a challenge regarding chemical recycling. Another weak point is the product concentration. After the comminution stage the product concentration is below 0.5%. Good progress was made in the concentrating studies, but the drying method used, freeze drying, is technically undesirable. While simple thermal drying is not effective, methods such as fluid bed drying or spray drying deserve further study. Due to the large amounts of water removed, the drying technique used must be combined with mechanical dewatering in order to become economically feasible.

Figure 15. SWOT analysis of cationic water-soluble cellulose.

Helpful to achieving business success Helpful to achieving business success

Process related

STRENGTHS

•Growingdemandforbothbio-basedwater

treatment chemicals and for cationic

polymers as a whole

•Legislationmaysupportdevelopmentof

bio-based cationic chemicals

•Economicfeasibilityseemsattainable

WEAKNESSES

•Reagentrepresentstoohighshareoftotal

production costs.

•DITreactorcanoperateathighconsistency

but processing high viscosity material

streams may be challenging.

•Expensiveandharmfulreagentneeded

with a risk of harmful residues


OPPORTUNITIES

•Bio-basedreplacementforc-PAM

•Newend-usefordissolvedcellulose

•NewbusinessopportunitiesforFIBIC

•CMCproductionisalreadyexisting,same

analogy could be used here

•Potentialbiodegradability

THREATS

•Productqualitycannotreachc-PAM

•Fullsustainabilityassessment(cradle-

to-grave) may not show significant

improvements to c-PAM

•Bio-basedmonomerdevelopment


Thus although none of the processes is ready as such, there are several options for further development, either each route separately or by combining the best parts from each one. Other interesting reaction routes, which remained outside the scope of the present study, should also be examined. In addition, the Michael type addition reactions, to which the MIPCl route also belongs, gave very interesting and well-performing samples, although more work is required to find a substitute for trifluoroacetic acid used in it.

Although the derivatives did not generally perform as well as the reference polyacrylamide, their performance matched the reference when combined with polyacrylamides. In some applications, such as high shear condition flocculation and pitch control by fixing, some of them performed even better than the reference products.

Flocculating applications that do not require very high charge densities may be more attractive in the first instance, as the reaction efficiency with these was the highest. However, this depends heavily on the chosen reaction route.

Efficient raw material utilization and low-cost and low-toxic reactants are the key issues in the successful cationization of cellulose. The ultimate solution for producing cationic cellulose may be based on one of these processes, or be a combination of several of them. The final success of cellulose cationization will depend not only on process efficiency, but also on how raw material prices develop compared to the raw material prices of synthetic polymers.

6. Networking

The research was carried out jointly and exclusively by the programme partners, see Table 7.


Partner Role

Glocell Qvantitative economic modelling.

Kemira Steering of overall work. Sample characterization and application testing. Defining, steering and providing competence for the modelling. Providing industrial insight to techno-economic assessments.

Metsä Fibre Industrial tutor. Providing industrial insight to techno-economic assessments.

Pöyry Management Consulting Market study. Economic feasibility modelling. Business potential evaluation.

Stora Enso Industrial tutor. Providing industrial insight to techno-economic assessments.

University of Helsinki•OrganicChemistry

Synthesis development of water-soluble polymers. New routes.

University of Oulu•FibreandParticleEngineering

Synthesis development of cationic particles.

UPM-Kymmene Industrial tutor. Providing industrial insight to techno-economic assessments.

VTT Synthesis development of water-soluble polymers. GTAC routes. Techno-economic modelling.



Publications

Liimatainen, H, Suopajärvi, T, Sirviö, JA, Hormi, O. and Niinimäki, J. Fabrication of Cationic Cellulosic Nanofibrils through Aqueous Quaternization Pretreatment and Their Use in Colloid Aggregation. Carbohydrate Polymers 103,2014:187-192.

Presentations

Ahlgren, J., Jääskeläinen, H., Kurkinen, S., Rouhiainen, J., Salmenkivi, K., and Hult Mori, E-L. New products: The market potential for cationic cellulose chemicals. FuBio Cellulose Seminar, Espoo, June 12, 2012.

Ahlgren, J. Cationic chemicals. FuBio Seminar, Espoo, October 1, 2012.

Posters

Karisalmi, K. and Kyllönen, L. Activation studies in cellulose derivatization. FuBio seminar,Espoo,August27,2013.

Kavakka, J., Sievänen, K., Labaf, S., Lagerblom, L., Kilpeläinen, I., Karisalmi, K. and Ahlgren, J. Towards Cationic Cellulose: Reactive Dissolution Approach. FuBio Seminar, Espoo, June 12, 2012.

Kavakka, J., Sievänen, K., Labaf, S., Lagerblom, L., and Kilpeläinen, I. Towards Cationic Cellulose: Reaction Dissolution Approach. FuBio Seminar, Espoo, October 1, 2012.

Liimatainen H, Sirviö J, Niinimäki J and Hormi O. Cationic cellulose particles as flocculation agents. FuBio Programme Seminar, Espoo, June 12th, 2012.

Sievänen, K., Kavakka, J., Fiskari, J., Vainio, P., Karisalmi, K. and Kilpeläinen, I.2013.Synthesisof Cationic Cellulose derivative for Wastewater Treatment. FuBio Programme seminar, Espoo, August27,2013.

Vuoti, S., Setälä, H. and Karisalmi, K. 2013. Cellulose cationization in water. FuBioProgrammeseminar,Espoo,October22th,2013.

ABBREVIATIONS

Pulp types: see Table 1Reactionroutes:seeTable3

• CMC=carboxymethylcellulose• CST=capillarysuctiontime;asludgedewateringtestingmethod• DP=degreeofpolymerization;correspondstomolecularweight• DS=degreeofsubstitution;correspondstochargedensity• FBRM=focusedbeamreflectancemeasurement;adynamicflocsizemeasuringmethod• GTAC=glycidyltrimethylammoniumchloride;acationizationreagent• NMR=nuclearmagneticresonancespectroscopy• PCC=precipitatedcalciumcarbonate

The FuBio Cellulose programme focuses on promoting selected novel

value chains starting from wood derived cellulose. The specific target of

the programme is to develop novel sustainable processes for production

of staple fibres, new cellulose based materials and water treatment

chemicals. The programme provides knowledge and capabilities

supporting the new value chains based on wood cellulose products.

www.fibic.fi

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Future BiorefineriesProducts from Dissolved Cellulose


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