World’s Leading Hydrocolloid Solutions Provider

1st

Edition

Carb

oxymethylcellulose (C

MC

)CCMMCCBBooookk

www.cpkelco.com

Äänekoski

Nijmegen

The core business of CP Kelcois hydrocolloids. CP Kelcoholds #1 positions in pectin,xanthan gum, and CMC(sodum carboxymethylcellulose- a versatile, water soluble,cellulose-based polymer), as well as a leading position incarrageenan.

Manufacturing sites in Europe

CP Kelco – The World Leader in Carboxymethylcellulose (CMC)

Production

CP Kelco has been producingCMC since the early 1940'sand has extensive knowledgeof the manufacturing processand the products. Backed byits customers' cooperation andsupport, the company hasgrown into the world's leadingproducer of CMC.

CP Kelco manufactures CMC at three production sites: in Finland, Sweden, and in the Netherlands. The quality ofour product meets the require-ments of both new and long-standing customers.

Contents

CMC manufacture .............................................................. 2

Trademarks ....................................................................... 5

Properties of CMC solutions ........................................... 6

1. Dissolution of CMC 6

New development in dissolution of CMC

2. Viscosity and rheology of CMC solutions 8

3. Molecular weight 9

4. Concentration 9

5. Temperature 10

6. pH 11

7. Influence of electrolytes 12

8. Influence of DS on solution characteristics 14

9. Stability 16

10. Shelf life 16

11. Blending 17

Environment and Safety ................................................... 19

Compatibility with other polymers ................................... 20

1. Nonionic cellulose derivatives 20

2. Other polysaccharides 20

3. Proteins 21

Some important applications of CMC .............................. 22

Modifications of CMC ........................................................ 23

Analytical Methods for CMC ............................................. 23

1. Moisture content 23

2. Viscosity 24

3. CMC content of technical grades 24

4. CMC content of purified grades 24

5. Degree of substitution, DS 24

6. Determination of pH 24

CMC stands for carboxymethylcellulose. However,CMC is more correctly the sodium salt of carboxymethylcellulose. It is derived from cellulose,which is made water-soluble by a chemical reaction.The water-solubility is achieved by introducing carboxymethyl groups along the cellulose chain, which makes hydration of the molecule possible.

CMC Manufacture

Suspending

Binding

Water retentionFormation ofnetwork structure

Film forming

Thickening

Stabilizing

CMC

The substituents are irreversibly linked to the cellulosebackbone with ether bridges, and thus, CMC belongs to the group of substances called cellulose ethers. It is important to note that the carboxymethyl grouphas an acid function meaning that CMC is an anionicpolyelectrolyte.

CMC has many interesting properties when dissolvedin aqueous solutions, but this will depend on the CMCgrade and the solution conditions.

2

The cellulose is carefully selected to meet the verystrict quality requirements of the end product. It is first treated with sodium hydroxide. Alkali cellulose isformed in the reaction between cellulose and sodiumhydroxide. This is a crucial step in the process toensure that the cellulose is homogeneously convertedto alkali cellulose.

CMC is produced from cellulose and monochloroacetic acid (MCA) and with sodiumhydroxide (NaOH) as the third essential ingredient. The different steps in the CMCprocess are described in the flow sheet below.

After completion of the different reaction steps theproduct contains about 25-35% of by-product salts(sodium chloride and sodium glycolate). It can be dried as it is (technical grade CMC) or neutralized andrefined by washing either to minimum 98% purity(FFIINNNNFFIIXX® CMC purified grades) or minimum 99.5%purity (CCEEKKOOLL® cellulose gum grades).

Technical CMCRefined CMC

Cellulose NaO

H

MC

AN

aMC

A

acid washing

liquor

cellulosegrinding

mercerization etherification

drying

grinding bagging sieving

grinding

dryingwashing

The alkali treatment step is commonly known as mercerization. The alkali cellulose is accessible andreactive towards monochloroacetic acid, which isadded to the reactor either as free acid—MCA, or asits sodium salt—NaMCA.

The basic elements of PAC (polyanionic cellulose) aresimilar to those of CMC. It is, however, made fromspecially selected cellulose raw material and manufac-tured under specific process conditions that ensure theunique characteristics typical of PAC.

SSttrruuccttuurree ooff cceelllluulloossee aanndd ooff ssooddiiuumm ccaarrbbooxxyymmeetthhyyllcceelllluulloossee

CH2OCH2COONa OCH2COONa OCH2COONaCH2OH

CH2OH CH2OH

OH

OH

OHOHOH

OH

CH2OH OH OHCH2OH

CH2OH CH2OH

OH

OH

OHOHOH

OH

3

Trademarks

To serve its diverse markets, CP Kelco water-soluble polymers are producedin a large number of grades with a variety of specifications and performances.The different grades are marketed under different product trademarks:

TM

TM

®

CMC for industrial applications. Available as purified and technical grades.

More detailed information about CP Kelco's CMC products can be found inthe brochure “Standard Grades & Graphs of CMC”.

The CAS number for Sodium CMC is 9004-32-4.

Cellulose gum for food, cosmetics, personal care, and pharmaceuticals.

Special CMC grades for pharmaceuticals.

PAC for oil and gas drilling.

Semi-pure PAC for oil and gas drilling.

Special CMC grades for use as thickener in textile printing pastes.

Efficient binders developed for use in building products.

Purified cellulose ether products specially developed for use in water-basedemulsion paints.

Liquid pumpable CMC dispersion. An attractive alternative to powder CMC,when dissolution capacity is a constraint.

5

Properties of CMC Solutions

11.. DDiissssoolluuttiioonn ooff CCMMCC

The method of dissolving the CMC and the extent ofagitation (shear) during dissolution, will ultimately influ-ence the final viscosity of the solution. The solvent, thechemical composition of the CMC and the shear histo-ry of the final solution affect the dissolution propertiesof CMC, i.e. hydration of the CMC molecules. Thismeans that standardized conditions for CMC dissolu-tion are essential for viscosity control of the resultingsolution.The principle of dissolving CMC is to wet all particlesas quickly as possible before the viscosity starts todevelop. CMC is by nature hydrophilic ("water-loving"),which means that the CMC particles will instantly start

to swell (hydrate) and dissolve when dispersed inwater. Therefore, the mixing device used must be efficient enough to keep the entire liquid in motion toavoid agglomeration or lump formation. The mixershould create a strong downstream flow in the centerof the dissolution tank and CMC should be added tothe vortex formed by the stirrer (FFiigguurree 11). It is essentialto emphasize that the rate of CMC addition must beslow enough (and even) to permit the particles tobecome individually wetted.

Addition can be done through a funnel or more prefer-ably with an inductor. However, the rate of additionmust be balanced to minimize viscosity build up of theaqueous phase while the CMC is being added.

CMC shows good solubility in both cold and hot water.The rate of dissolution increases at elevated tempera-tures because the viscosity of the solvent and of thedeveloping CMC solution is lower at high temperature.The dissolution rate of the CMC molecule is independ-ent of temperature. When heating is possible, a suit-able (and recommended) temperature to prepare aCMC solution is at about 50-60 °C.The dissolution rate of CMC also depends on the particle size. Provided that all particles have been indi-vidually wetted and no lumping occurs, a fine powderwill always dissolve faster compared to a more coarsematerial. The dissolution profile for different particlesizes is illustrated in FFiigguurree 22, expressed as the torsionexperienced by the stirrer.

FFIIGGUURREE 11: Dissolving of CMC

FFIIGGUURREE 22: The dissolution time of several particle size ranges expressed in torque values

0-0.2 mm

0-0.3 mm

0-0.5 mm

0.2-0.5 mm

Time

7

6

5

4

3

2

1

0

Torq

ue, N

cm

6

Recommended solution concentration for some CMC grades, to achieve asolution viscosity of about 2000 mPa•s (at room temperature, Brookfield LVT,spindle 3, 30 rpm), is given below.

DDeevveellooppmmeennttss iinn ddiissppeerrssiioonn//ddiissssoolluuttiioonn ooff CCMMCC

CMC can be chemically modified, which provides excellent dispersionproperties of the powder and retarded dissolution characteristics underneutral or slightly acidic condition. If the dispersion is kept at neutral pH,dissolution will eventually take place, starting after approximately 15-20minutes. However, by increasing the pH of the dispersion dissolution (atany time) can be triggered (see FFiigguurree 33). Even though a chemically modified CMC is an elegant way to control dissolution, this approach has certain limitations and this type of modifiedCMC can only be used in special applications.

Specialized dry addition of CMC is employed in certain industries, forinstance – in the paper and board coating industries. This simplifies handlingof the dry CMC and also eliminates the need of a special dissolution stationas well as storage tanks.

CP Kelco has developed a liquid CMC dispersion specifically for use inthe paper coating industry. The dispersion dissolves readily in the coatingformulation and is easy to handle. Furthermore, the product has excellentstorage stability.

FFIINNNNFFIIXX® ggrraaddee oorr CCEEKKOOLL® ggrraaddee MMaaxx.. ccoonncceennttrraattiioonn,, %%

10 10

30 7

300 3

4 000 1.5

30 000 0.8

FFIIGGUURREE 33:: Hydration profile of special treated CMC, retarded hydration

0

5.0

1

5.1

2

5.2

3

53035202510150 Time, minutes

Torq

ue, N

cm

Hydration time Hydration time with NaOH addition at 5 min.

7

Apparent viscosity

Shear rate

Δt

1

10

100

1,000

10,000

1 10 100 1,000 10,000

Shear rate, 1/s

Visc

osity

, mPa

•s

CEKOL 30 CMC

CEKOL 700 CMC

CEKOL 30 000 CMC

22.. VViissccoossiittyy aanndd rrhheeoollooggyy ooff CCMMCC ssoolluuttiioonnss

The most important and useful property of CMC is itsability to impart viscosity to its aqueous solutions.Solutions can be prepared in a wide range of viscosi-ties. CMC products range from low molecular weightto high molecular weight polymers. The solutionsbehave, consequently, from almost Newtonian toincreasingly pseudoplastic, meaning that the viscositywill change when different physical forces are imposedon it.The viscosity depends on the shear applied. This isexperienced in practice as a decrease in viscosity

FFIIGGUURREE 55: Thixotropic flow behavior depictedin viscosity profile (Δt illustrative ofrestore of viscosity)

FFIIGGUURREE 44:: Effect of shear rate on viscosity of a 1% solution of a low, medium, and highviscous CCEEKKOOLL CMC

when a CMC solution is stirred, pumped or sheared in some other way. The pseudoplastic flow behavior is related to de-entanglement and orientation of theCMC molecules in the direction of the flow. A longermolecule (higher molecular weight), as found in CCEEKKOOLL 3300 000000 CMC,, is far more "shear thinning"compared to the shorter chain molecule found inCCEEKKOOLL 770000 CMC (see FFiigguurree 44). The viscosity of thelow molecular weight CCEEKKOOLL 3300 CMC is hardly influ-enced by the shear rate, meaning that the flow behav-ior of a CCEEKKOOLL 3300 CMC solution is almost Newtonian.

When the shear stress is increased, the viscosity(resistance to flow) will decrease. The viscosity changeis completely and instantaneously reversible and theoriginal viscosity is retained when the shear stops. It isimportant to note that due to pseudoplastic flow prop-erties of a CMC solution, a measured viscosity value isonly valid for a defined shear rate. The term 'apparentviscosity' is often used to denote that it is not a definitevalue but only true under certain conditions.

A property related to the polymeric nature of CMC,and often mixed up with pseudoplasticity, is thixotropy.This has to do with interaction between the long-chainCMC molecules and the development of a three-dimensional structure (network) in the solution. Whensufficient shear stress is exerted on a thixotropic solu-tion, the structure can be broken and the apparent vis-cosity reduced. The viscosity change is reversible buttime-dependant and the original viscosity will beretained when the solution remains at rest for a periodof time after shearing (FFiigguurree 55).

8

33.. MMoolleeccuullaarr wweeiigghhtt

The viscosity is proportional to the aver-age chain length of the CMC molecule or the degree of polymerization (DP). The average chain length and the degreeof substitution determine the molecularweight of the CMC grade. The viscosityincreases rapidly with increasing degreeof polymerization.

Approximate values for the degree ofpolymerization and the molecular weight(weight averages) of some CP KelcoCMC grades are given in TTaabbllee 11.

TTAABBLLEE 11: Typical molecular weight averages for some CP KelcoCCEEKKOOLL CMC and FFIINNNNFFIIXX CMC grades (DS = 0.8)

GGrraaddee DDeeggrreeee ooff ppoollyymmeerriizzaattiioonn MMoolleeccuullaarr wweeiigghhtt,, MMww

30 000 3 200 750 0004 000 2 000 450 000700 1 200 270 00030 360 80 000

44.. CCoonncceennttrraattiioonn

The viscosity of a CMC solution increasesrapidly with concentration. A fairly goodrule of thumb is, that viscosity increaseseight to ten fold when the concentrationis doubled.

FFiigguurree 66 shows the relationship betweenviscosity and concentration for somepurified CP Kelco CMC grades. From thisgraph it can be seen that a 0.5% solutionof a 30 000 grade will show the same vis-cosity as a 2.5 % solution of a 700 grade.However, this does not imply a similarfunctionality in applications because thefunctionality depends on multiple addi-tional factors.

DDSS = Degree of SubstitutionThe approximate molecular weight is calculated from:DP x (162 + 80 x DS) = Mw

Visc

osity

25°

C

Concentration % (dry basis)0 1 2 3 4 5 6 7

mPa•s

10,000

1,000

100

10

30 0004 000

700

30

5

FFIIGGUURREE 66: Viscosity of FFIINNNNFFIIXX / CCEEKKOOLL CMC of variousconcentrations in demineralized water

9

55.. TTeemmppeerraattuurree

The viscosity of a CMC solution is reversibly tempera-ture dependant i.e. the viscosity decreases when thetemperature is increased but the original viscosity isregained when the temperature is lowered to the starting value. Heating for longer periods, in particular if the temperature is above 100 °C may cause loss of viscosity, depending on the grade (see FFiigguurree 77). The viscosity/temperature relationship for some purified CP Kelco grades is illustrated in FFiigguurree 88.

0

400

800

1,200

1,600

2,000

Visc

osity

, mPa

•s

10 minutes80°C

2,400

1 minute120°C

60 minutes120°C

60 minutes120°C (high ds)

Initial viscosity

Viscosity afterheating andcooling

Visc

osity

Temperature °C 10 20 30 40 50 60 70 80

mPa•s

1,000

100

10

1% 30 000

2% 700

4% 10

4% 30

Viscosity

Heating Cooling

FFIIGGUURREE 77: Effect of heat treatment on CCEEKKOOLL 3300 000000 CMC 1% in demineralized water

FFIIGGUURREE 88: (left) Effect of temperature on the viscosity of various aqueous solutions of FFIINNNNFFIIXX / CCEEKKOOLL CMC(right) Effect of heating at temperatures < 100 °C

10

66.. ppHH

The viscosity of CMC solutions is stable within a widepH range (FFiigguurree 99). At pH levels of 11-12 and higher,the viscosity is affected due to the high electrolyte concentration prevailing and alkaline degradation(hydrolysis) of the CMC molecule. At a pH <4 the acidform of CMC is beginning to dominate (the Na+ count-er-ion will be replaced by H+). This type of CMC isinsoluble in water resulting in a decrease in the viscosi-ty. However, high DS CMC grades and special acidstable grades will show good viscosity stability evenunder hostile low pH conditions.

CEKOL 30 CMC

CEKOL 30 000 CMC

100

1,000

10,000

4.0 7.0 9.0 12.0

pH

Viscosity , mPa•s

FFIIGGUURREE 99:: Effect of pH on the viscosity of CCEEKKOOLL 3300 CMC and CCEEKKOOLL 3300 000000 CMC

11

77.. IInnfflluueennccee ooff eelleeccttrroollyytteess

The effect of inorganic salts on the viscosity of a CMCsolution depends mainly on the ability of the cation ofthe salt to form a soluble salt with CMC. The compatibility depends, besides the cation, on the concentration of the inorganic salt and the CMC.The properties of the CMC (degree of substitution and the distribution of the substituents) are of para-mount importance to enhance the viscosity stability inaqueous electrolyte solutions. It should also be notedthat the preparation of the solution often has a strongeffect on the final solution viscosity. Generally, the viscosity is less affected if the electrolyte is added to a water solution of CMC rather than dissolving theCMC in the aqueous electrolyte solvent.

Monovalent ions will generally form soluble salts withCMC, while divalent and polyvalent ions form insolublecomplexes with CMC. Although calcium CMC is waterinsoluble, a low number of calcium ions in the sodiumCMC molecule will not make it water insoluble. Silver is atypical as well – it forms an insoluble saltdespite being monovalent.

For a low substituted CMC grade, considerable differ-ences in viscosity may be seen if salt is added beforeor after the CMC is dissolved. When salt is added to a CMC solution, it will hardly affect the viscosity (noteven after a long storage time) while a CMC dissolvedin an aqueous electrolyte solvent may show a muchlower viscosity than expected. High substituted CMCis less sensitive towards electrolytes than medium orlow substituted grades. The reason for this is that,although some of the sodium ions of the CMC will bereplaced, there is still enough unpreturbed Na-CMC to maintain the viscosity.

0 1 2 3 4 5 6

1,000

100

10

% NaCl in solution

FINNFIX 700 CMC

FINNFIX 30 CMC

0 1 2 3 4 5 6

1,000

100

10

FINNFIX 700 CMC

FINNFIX 30 CMC

% CaCl 2 in solution

FFIIGGUURREE 1100: Effect of electrolyte on solutions of low and medium viscosity CMC

12

Electrolyte effects are most pronounced on high vis-cosity grades. For low viscosity grades no effect or even an opposite effect (viscosity increase) may occur.The effect of salt on the viscosity of a CMC solution isillustrated in FFiigguurree 1100. It should be noted that FFiigguurree 1100 shows the viscosity behavior when CMC hasbeen dissolved in the aqueous salt solution.

The CMC molecule will change its configuration (coilingwill occur) in solution when exposed to various types of electrolytes (salts, acids, or alkalis) often resulting in a decrease in the viscosity. This effect is commonlyknown as the “polyelectrolyte effect” and is most pronounced in dilute solutions (< 0.5% solute concen-tration). At higher concentration the effect diminishesbecause the migration of the counter-ions is restricteddue to the high local viscosity in the solution. The presence of an electrolyte will (in most cases) also

affect the solubility of the CMC molecule as discussedabove. A high viscosity grade is normally more affectedby the presence of electrolytes compared to a mediumor low viscosity grade since the high viscosity gradesare generally used at a lower concentration and thismeans that the "polyelectrolyte effect" will be more visible. The electrolyte compatibility can be improvedby increasing the degree of substitution of the CMC(see § 8). Equally important is the selection of rawmaterials and process conditions during manufacture.FFiigguurree 1111 and FFiigguurree 1122 illustrate some properties ofhigh viscosity grades compared to a medium viscositygrade when the CMC has been dissolved in 5% aceticacid (pH of the solution was 3.4). The CCEEKKOOLL AAgrades are specially developed to be highly compatiblewith various types of acids. Even more important isthat solutions of these grades stay transparent while a solution of a standard grade becomes hazy underacidic conditions (see FFiigguurree 1122).

0

400

800

1,200

1,600

2,000

Broo

kfie

ld v

isco

sity

, mPa

•s

CEKOL 30 000ACMC

CEKOL 10 000ACMC

High visco food grade

CEKOL 700CMC

Viscosity inwater

Viscosity inacetic acid

0

2

4

6

8

12

Turb

idim

eter

val

ue, N

TU

CEKOL 30 000ACMC

CEKOL 10 000ACMC

High viscofood grade

CEKOL 700CMC

Cellulose gum grade

10

14

FFIIGGUURREE 1111:: Comparison of viscosity of various CCEEKKOOLL CMC grades in water and in 5% acetic acid

FFIIGGUURREE 1122:: Comparison of the clarity of solutions of CCEEKKOOLL AACMC grades and CCEEKKOOLL CMC standard products in 5% acetic acid

13

88.. IInnfflluueennccee ooff DDSS oonn ssoolluuttiioonn cchhaarraacctteerriissttiiccss

The degree of substitution, DS, is one of the mostimportant properties of CMC. It not only influences thesolubility of the CMC molecule but also affects the solu-tion characteristics. By definition, the DS is the averagenumber of carboxymethyl groups per anhydroglucoseunit. Theoretically, the maximum DS is 3. The normal DS range for commercially available CMC is approx. 0.5 - 1.5.Higher degrees of substitution will normally improve thesolubility of the CMC and enhance the viscosity stabilityin the presence of salts or at low pH.

CH2OCH2COONa

OCH2COONaCH2OH

CH2OH

OH

OH

OH

OH

CH2OCH2COONa

OC 2COO a

OH

CH2OH

CH2OH

OH

The degree of substitution of the CMC molecule has a major influence on the solution characteristics. The main effects are summarized in FFiigguurree 1133.

DEGREE OF SUBSTITUTION

Interaction via H-bonding

Thixotropy

Interaction via -COO- groups

Clarity of the solution

Stability

FFIIGGUURREE 1133: Influence of the degree of substitution

14

SDsuoeuqa %2 ,)•saPm( .csivEDARGnoitulos

07.0054I07.0554II

Not only the DS level but also the distribution of thesubstituents along the chain will influence the solutioncharacteristics of the CMC. The rheological behavior of a CMC solution and the compatibility with other soluble components will be affected by the substitutioncharacteristics. An aqueous solution of an unevenlysubstituted CMC (normally at a DS < 0.7) will oftenexhibit thixotropic (see FFiigguurree 1144) behavior due to thedevelopment of a three-dimensional network in thesolution. This behavior will be more pronounced inmixed solvents. This is illustrated in FFiigguurree 1155.

Both CMC types show a 'viscosity bonus effect' (synergy) in this solvent. However, the synergistic effectwill be strongly influenced by the distribution of thesubstituents. This is clearly illustrated by the perform-ance of CMC type I.This type (i.e. CP Kelco CCEEKKOOLL® 550000TT cellulose gum)is an efficient gelling agent with a unique distribution of the substituents.Higher degrees of substitution give products havingimproved resistance to enzymatic degradation.However, these CMC grades are still biodegradable.

FFIIGGUURREE 1155: Effect of mixed solvent (glycerin/water) on the viscosity of CMC with different substitution patterns

FFIIGGUURREE 1144: Effect of the substitution pattern on the rheology

Shear rate

Viscosity

CEKOL I – high structure

CEKOL II – low structure

0 1 2 3 4 5 6 7 8 9

10,000

1,000

Visc

osity

Time, days

mPa•s

Unevenly substituted

Evenly substituted

I

II

15

99.. SSttaabbiilliittyy

Although CMC has good stability towards degradation– enzymes and oxidants may still degrade it. Enzymes,either added as such or produced by microorganisms,may degrade the cellulose chain, and thus, cause serious, irreversible viscosity decreases.

The normal route of enzyme contamination is viamicroorganisms, present in the environment. Theseinfect the system where CMC is used and start pro-ducing enzymes. An efficient way to stop enzymaticattacks is thus to prevent growth of microorganisms.This can be done by heat treatment or by adding preservative. Heating for about 30 minutes at 80 °C, or about 1 minute at 100 °C is normally sufficient todestroy the microorganisms. Complete inactivation ofpossibly present cellulolytic enzymes may require asomewhat higher temperature and/or longer time. Some preservatives suitable for CMC solutions are listed below.

Further information about type and amount of preser-vative should be requested from the preservative man-ufacturer.

Formaldehyde Phenol Thymol

Dowicide(Dow)

Santobrite(Monsanto)

Hydroxyquinoline 2-Biphenylol

Suitable preservatives for food, cosmetic and pharmaceutical uses are given below.

Sodium benzoate | Sorbates (Na and K salts)

Sodium propionate | Methyl parahydroxybenzoate

1100.. SShheellff lliiffee

All CMC grades are derived either from wood pulp or,sometimes, also from cotton linter. They arebiodegradable and this also means that the shelf life ofthese products is limited. Consequently, it is importantto store these products in a correct way to preventunnecessary degradation.

Never store CMC in open bags.

CMC is hygroscopic, meaning that it easily absorbsmoisture from the environment. The product should bestored in its original packaging, in a dry and well-con-ditioned place. It is important to keep the storage areadry, clean, and dust free.

The properties of CMC mostly affected during storage are moisture and viscosity.

Oxidants, e.g. chlorine and hydrogen peroxide, causedegradation of the cellulose chain. Oxidative degrada-tion occurs under alkaline conditions in the presence of oxygen. Metal ions, like Fe2+ accelerate alkalinedegradation.

To prevent oxidative degradation, CMC solutionsshould not be exposed to the open air for longer thannecessary, especially at elevated temperatures and pH.During prolonged storage, the CMC solutions shouldbe preserved as soon as possible after preparationand (if possible) maintained at neutral pH. Oxygen andsunlight should be excluded.

Provided the product is stored as outlined above, mostCMC grades remain in good condition for a period ofabout 3 years. However, in general it is recommendednot to store CMC longer than 1 year, since even duringappropriate storage some minor changes in the chemi-cal properties of the product are unavoidable. This is,in particular, the case for high viscosity grades, whereas an extra precaution before use, a re-check of thechemical properties already after 6 months storage isrecommended.

It is important to use clean equipment when handlingCMC, to avoid possible microbial contamination.

16

1111.. BBlleennddiinngg

In order to achieve a specific viscosity it is possible toblend two or more CMC grades with different viscosi-ties. The resulting viscosity of the blend can be calcu-lated by using the formula:

Where:Vb = viscosity of the blend

a1 = the amount of component 1

v1 = the viscosity of component 1

a2 = the amount of component 2

v2 = the viscosity of component 2

If only two components are used the viscosity of theblend can easily be determined from the logarithmicdiagram shown in FFiigguurree 1166.

a1 v gol 1 a + 2 v gol 2 ... + vgol b –––––––––––––––––––––––––– = a1 a + 2 ... +

10,000

1,000

500

200

mPa•s

2,000

5,000

100 90 80 70 60 50 40 30 20 10 0

0 10 20 30 40 50 60 70 80 90 100

Component A %

Component B %

FFIIGGUURREE 1166: Logarithmic blending diagram

17

Environment and Safety

CMC has been extensively evaluated by bothWHO/FAO Joint Expert Committee on Food Additives(Jecfa) and by the Scientific Committee for Food in theEuropean Union. The results of both toxicological evaluations were that no adverse toxicological effectscould be identified.

Aquatic organisms are exposed to CMC due to occa-sional direct discharge of CMC into surface water. Noharmful effects to aquatic organisms of various CMC and their intermediates have been detected.

Partial biodegradation of CMC in activated sludgeplants also necessitates assessment of the aquatictoxicity of the intermediates formed during the bio-degradation process. Tests made with intermediates ofCMC (DS=0.7) reveal that the biological treated CMCdoes not exhibit toxicity. Acute and chronic toxicity ofCMC (DS=0.7) and of the biodegradation intermediateof this CMC to aquatic organisms are summarizedbelow. All no-effect concentrations (NOEC) values werethe highest concentrations tested.

TESTORGANISM

OECD Guideline

Duration (hours)

EndpointCMC concentration, g/l

Intermediate concentration, g/l

Pseudomonas putida

96 NOEC 1.0 *

Selenastrum capricornutum

201 96 NOEC 0.5 0.5

Daphnia magna 202 48 NOEC 5.0 1.0Brachydanio rerio 203 96 NOEC 2.5 1.0

* Not determined

0

20

40

60

80

Biod

egra

datio

n, %

0 50 100 150 200 250 300

Time, days

7,200 mPa•s(1% soln.)

1,200 mPa•s(2% soln.)

29 mPa•s(6% soln.)

Bio

deg

rad

atio

n, %

0 50 100 150 200 250 300

Time, days

0

20

40

60

80

DS = 0.57

DS = 0.85

DS = 1.20

Biodegradation of a wide range ofCMC types has been studied in labora-tory scale with the purpose to simulateconditions on wastewater treatmentplants and natural ecosystems. A pro-longed Closed Bottle test method wasused. The test results show that therate of biodegradation of CMC isdependent on the molecular weight(see FFiigguurree 1177). The DS and the rate of biodegradation have an inverse rela-tionship (see FFiigguurree 1188). This is in linewith other tests where CMC solutionshave been innoculated with Cellulase.The rate of enzymatic degradationdecreases with increasing DS.The biodegradation of all CMC typeswas >60%, indicating completebiodegradation. Furthermore, CMC(DS=0.6) labelled with 14C in the car-boxymethyl group, was subjected tonaturally occurring microorganisms in a batch culture. 84% of the 14C wasrecovered as carbon dioxide after 16weeks, demonstrating the susceptibilityof the carboxymethyl groups tobiodegradation.

FFIIGGUURREE 1177:: Effect of the molecular weight on the rate of biodegradation

FFIIGGUURREE 1188:: Effect of the degree of substitution on the rate of biodegradation

The data in the Table is obtained from the publication: Ginkel C.G. van and Gayton S., Environmental Toxicology Chemistry 1155, 270-274, 1996

19

Compatibility with Other Polymers

11.. NNoonniioonniicc cceelllluulloossee ddeerriivvaattiivveess

CP Kelco CMC products are compatiblewith most nonionic cellulose derivativesover a wide range of concentrations.However, when working with blends of CMC and nonionics it is sometimesadvisable to select reasonably similar viscosity grades unless very specialproperties of the blend are requested.Blends of CMC and a nonionic cellulosederivative will, in most cases, show asynergistic effect on viscosity. The poly-mer blend shows solution viscositiesconsiderably higher than would beexpected. This is illustrated in FFiigguurree 1199,where the viscosity behavior of blendsbetween FFIINNNNFFIIXX® 22 000000 + EHEC (ethyl-hydroxy-ethyl cellulose) [FFiigguurree 1199AA] andFFIINNNNFFIIXX® 330000 + MC (methyl cellulose)[FFiigguurree 1199BB] is depicted.

A B

Visc

osity

0 33 67 100

120

100

80

60

40

20

00 33 67 100

190

170

150

130

90

70

50

110

% CMC % CMC

mPa•s

Visc

osity

mPa•s

22.. OOtthheerr ppoollyyssaacccchhaarriiddeess

CP Kelco CMC products are fully com-patible with most other polysaccharides.With some, a synergistic viscosity effectmay be experienced and with others –the viscosity follows the theoreticallyexpected behavior. A few examples ofblends of CMC with different polysaccha-rides are given in FFiigguurree 2200.

FFIIGGUURREE 1199: Examples of viscosity behavior of blends of CMC and other cellulose ethers

FFIIGGUURREE 2200: Examples of the viscosity effect of blends of CMC and some other polysaccharides

5,000

500

100

mPa•s

1,000

MeasuredTheoretical

0 % CMC 100 % Alginate 0 % CMC 100100 % Guar gum 0 % CMC 100 % Xanthan gum 0

20

33.. PPrrootteeiinnss

Proteins are polymers of amino acids and occur in alarge number of different shapes. These have severalproperties in common, one of which is their pH-sensi-tivity. This makes their water solubility restricted torather narrow pH-intervals. However, due to the ionicnature of CMC, it can interact with many proteins toform soluble and stable complexes. This is especiallyimportant for proteins showing an iso-electric point (thepH where the solubility normally is poorest) near orbelow neutral. An important example is stabilization ofmilk protein (casein) with CMC in sour milk products.The iso-electric point of casein in milk is approx 4.6.The reaction of a protein and CMC around the iso-electric point is illustrated below.

500

100

mPa•s

1,000

Visc

osity

pH

2 3 4 5 6 7 8

1% CMC + 0.5% Na-caseinate

0.75% CMC + 0.5% Na-caseinate

0.5% CMC + 0.5% Na-caseinate

Cekol 10 000

FFIIGGUURREE 2211: Formation of a cellulose gum-protein complex

FFIIGGUURREE 2222: Stabilization of casein with CMC

OCH2COO-

CH2OCH2COO-

OCH2COO -

OCH2COO-

CH2OCH2COO-

OH

OH

CH2OCH2COO-

OH

COO-

NH3+ NH3+

CMC

Protein

OCH2COO-

CH2OCH2COO-

-

OCH2COO-

CH2OCH2COO-

OH

OH

CH2OCH2COO-

OH

COO-

CMC

Protein

-

21

Some Important Applications of CMC

Sodium carboxymethylcellulose, CMC, is one of the most diversified commercialthickening agents with respect to its industrial applications.

A review of some important applications of CMC is compiled below.

Paints

Adhesives

Personal care products

Pharmaceuticals

Food

Paper coating

Paper sizing

Ceramics

Textile sizing

Mineral flotation

Textile printing

Detergents

Drilling fluids

Thickening agentgives viscosity to anaqueous formulation

Protective colloidkeeps suspended particlesstable in suspension

Water retention agentprevents water from escaping

Film formation agentgives a mechanical- and

chemical-resistant film

Binding agentis able to bind large

amounts of water

Stabilising agentkeeps suspended particles

or dissolved molecules stable

Mainly purified FINNFIX® CMC grades, 98%

CEKOL® CMC and NYMCEL® CMC grades,purity criteria min. 99.5%

CELPOL® PAC grades and alsotechnical FINNFIX CMC grades

CELFLOW® cellulose ether andpurified FINNFIX CMC grades

CELLUFIX® CMC and purified FINNFIX CMC grades

Purified and technical FINNFIX CMC grades

CELLCOSAN® CMC

Technical FINNFIX CMC grades

through chemical interaction

22

(A – B) x 100 Moisture % =

A

Modifications of CMC

There are a number of interesting possibilities to modifythe CMC molecule either by using CMC as raw material to add other functional groups or modifyingCMC through chemical or physical treatments. A fewexamples will briefly be reviewed in this paragraph.

• ASSOCIATIVE PERFORMANCEAssociative performance can be achieved through ahydrophobic modification of the CMC molecule. Anexample of such a modification is given below, whereCMC is reacted with Alkyl Ketene Dimer (AKD), givinga surface active hydrophobic CMC molecule (J.M.Huber patent).

Depending on the degree of hydrophobicity as well asthe chemical composition of R1 and R2 respectively,unique and specific functionallity can be achieved withthis modified CMC.

• CROSSLINKINGCrosslinking of CMC can be done either through a chemical reaction or through heat treatment. Thedegree of crosslinking will affect the water solubility of the CMC molecule and, at a certain point, the molecule becomes insoluble in water. However, thismolecule is still very hydrophilic and has the ability toabsorb and retain considerable amounts of water oraqueous media. This ability combined with the factthat such a CMC type is still inherently biodegradable,makes it attractive for use as a superabsorbent.Special types of crosslinked CMC, so called cros-carmellose sodium, are extensively used in the phar-maceutical industry as disintegrants for tablets.Low or moderate crosslinking of the CMC moleculecreates a three-dimensional structure in solution, whichaffects the rheological properties. This type of CMCshows thixotropic flow behavior (see FFiigguurree 55) makingit attractive for use as an adhesive or as a thickener inapplications, where workability and flow characteristicsof the products are key elements.

R1 CH C CH R 2 + CMC O R2 O

R1 – CH2 – C – C – C O CMC O C O

H

R1 and R 2 C 6 – C 22

– – – –––

– –

––– ––

––– – –

––

Analytical Methods for CMC

Analysis may be carried out by various methods. CP Kelco CMC products are analyzed according to the following standard methods.

11.. MMooiissttuurree ccoonntteenntt

Weigh accurately 5 g sample of CMC in a beaker.

Let it dry for 4 hours at 105 ± 3 °C.

Cool the beaker in a desiccator for 30 minutes andweigh it again.

Where: A = weight of the original sample, gB = weight of the dried sample, g

23

22.. VViissccoossiittyy

Depending on the grade of CMC, the viscosity isdetermined in 4%, 2% or 1% aqueous solutions.

Mix the sample slowly into distilled water by stirringwith a wire mixer at 550-600 rpm. Increase the speedof the mixer to 700 ± 100 rpm and stir until the

33.. CCMMCC ccoonntteenntt ooff tteecchhnniiccaall ggrraaddeess

Determine the moisture content of CMC.

Wash 1 - 1.5 g CMC free from salts with 80% ethanol.

Dry and weigh the residual CMC.

44.. CCMMCC ccoonntteenntt ooff ppuurriiffiieedd ggrraaddeess

Determine the sodium chloride and sodium glycolatecontents of CMC according to the instructions of ASTM D 1439.

55.. DDeeggrreeee ooff ssuubbssttiittuuttiioonn,, DDSS

Weigh accurately 0.5 g sample of pure 100% CMC(salt free) in a crucible.

Ignite the sample first over a small flame until the sam-ple becomes charred, followed by 45 minutes in a kilnat 650 °C. Ash should be grayish white.

Dissolve the ash in a small amount of distilled waterand titrate with 0.1 N sulphuric acid and use methylred as an indicator.

66.. DDeetteerrmmiinnaattiioonn ooff ppHH

Dissolve CMC in distilled water into 1% solution andmeasure pH.

sample is completely dissolved. Stabilize the tempera-ture of the solution in a water bath to 25 ± 0.5 °C.

Viscosity is measured with a Brookfield LVT viscometerusing a spindle and speed according to the tablebelow.

Where: A = weight of the dried residue, gB = weight of the sample, gC = moisture of the sample, %

CCMMCC ccoonntteenntt,, %% == 110000 -- AA -- BB

Where: A = sodium chloride content, %B = sodium glycolate content, %

B = 0.1 x b/G= milliequivalents Na/g

of 100% CMC

Where: b = consumption of 0.1 N H2 SO4, mlG = weight of 100% CMC, g

AA xx 1100 000000 CCMMCC ccoonntteenntt,, %% == {{BB xx ((110000 --CC))}}

(0.162 x B) DS =

(1 – 0.080 x B)

VViissccoossiittyy rraannggee iinn mmPPaa•ss SSppiinnddllee SSppeeeedd,, rrppmm

< 100 1 60

100 - 500 2 60

500 - 2 000 3 60

2 000 - 4 000 3 30

4 000 - 20 000 4 30

> 20 000 4 12

24

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The information contained herein is, to our best knowledge, true and accurate, but all recommendations or suggestions are made without guarantee, since we can neither anticipate nor control the different conditions under which this information and our products are used. THERE ARE NO IMPLIED OR EXPRESS WARRANTIES OF FITNESS FOR PURPOSE. Each manufacturer is solely responsible for ensuring that their final products comply with any and all applicable federal, state and local regulations. Further we disclaim all liability with regard to customers' infringement of third party intellectual property including, but not limited to, patents. We recommend that our customers apply for licenses under any relevant patents.

All trademarks herein are owned by CP Kelco Oy. These marks are registered or pending registration in various countries around the world.

© 2006-2009 CP Kelco U.S., Inc.

Argentina CP Kelco Argentina S.A. Bolivar 187 - 6th A C1066AAC Buenos Aires Argentina Tel: +54 11 4331 8483 Fax: +54 11 4331 8483

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