WELCOME

M.L.V. TEXTILE & ENGG. COLLEGE, BHILWARA (An Autonomous Engineering College of the Rajasthan Govt.)

for

The Partial Fulfillment of the Requirements for Degree of Bachelor of Technologyin

Textile ChemistrySUBMITTED TO SUBMITTED BY

Dr. V.K.GUPTA

A Seminar on Chemical Processing of Micro Denier Fabrics

BRIJMOHAN SHARMA09EMBTC201

MICROFIBRES

. . . ?Micro fibres are –

Half the diameter of a fine Silk Fibre,

One-Third the diameter of Cotton,

One-Quarter the diameter of Fine Wool,

And One Hundred times finer than Human Hair…

INTRODUCTION

The growing demand to increase the fibre properties hitherto known, and to create new sophistical application fields for textile materials have been the causes of the rapid growth of microfibre technology and the rising potential for the textile industry. Microfibres are half the diameter of a fine silk fibre, one-third the diameter of cotton, one-quarter the diameter of fine wool, and one hundred times finer than human hair. Fabrics made from microfibres are generally lightweight, resist wrinkling, have a luxurious drape and body retain shape, and resist pilling. They are also relatively strong and durable in relation to other fabrics of similar weight, and they are more breathable and more comfortable to wear

Definition of MICROFIBRE

A microfibre is defined as a fibre of linear density approximately 1 d tex or less and above 0.3 d tex ……

Relationship b/w fibre linear density and classification…

Fibre Count (d tex) Fibre Classification

> 7.0 Coarse

7.0 – 2.4 Medium fine

2.4 – 1.0 Fine

1.0 – 0.3 Microfibres

< 0.3 Super- Microfibres

History of Microfibres

In 1970s Very 1stly Japanese fibre Manufacturing companies introduced The first “micro-denier “ products.

In 1980s - EUROPE

In 1990s - American fibre manufacturers

At present , Polyester and Nylon are generally used for manufacturing microfibres

PRODUCTION OF MICROFIBRES

Microfibres are generally considered to be fibres with a linear density of less than 1.0 dtex.Although the technology for microfibre production has been available for many years now, strongdemand for these fibres did not begin until the 1980s. The currently available microfibres are differentfrom ordinary fibres mainly in their dimensions, but have much lower property differences than thestandard fibres. Toray was the first company in the world to introduce microfibres, followed by Teijin,Hoechst, ICI, DuPont, and others. Recently Toray has introduced an ultra-fine polyester microfibrewith a linear density of filament of about 0.05 dtex. This may be called the finest synthetic fibre so farproduced commercially.

WHAT SHOULD BE THE QUALITY OF THE CHIPS FOR MICROFIBRE ?

• Composition should be consistent• Should not contain foreign matters• Moleculer weight distribution curve should also be narrow• Short term viscosity must be kept as much as possible• polymer chips should be smooth and identical in shape/size• Due to high value of microfibres, the use of “off – quality ’’ chips should be avoided

It is also important to maintain the quality of the product in all subsequent steps.The drying process should be as consistent as possible, and chips must have aneven residence time. The moisture regained of the dried chips should be less than 0.005%, to minimize the hydrolytic degradation in molten stage. For drying quality chips, a continuous drying process is better than batchdrying.

METHOD OF MANUFACTURING MICROFIBRES

a) DISSOLVED TYPE

Microfibres of this type are manufactured from bi-component fibres with different types of polymers.Comparatively thick bi-component filaments containing different types of incompatible polymers are spun, and the fabric is made using them. When the fabric is treated chemically with solvent, one component is dissolved and removed, and the other component remains as the microfibre. Polyester and nylon microfibres can be made by this method. Commercial production has been reported to use 20/80 ratios of soluble/insoluble polymers to produce a bi-component filament of up to 2 dtex fineness, and a final dissolved filament with linear density of about 0.50 dtex.The main considerations for selection of suitable polymer component are:

High solubility; Stability at extrusion temperature; It should be recoverable for use, so that the cost of solvent and soluble polymer is affordable; It should be non-toxic, non-corrosive, and non-polluting.

Bi-component Fibres

Bi-component fibres are co-extruded with two different polymers in thecross-section. This allows the fibre to use the properties of both materials,and vastly expands the array of possible fibre performance characteristics. Bi-component fibres are available in staple, filament, and microfibreforms. Typical bi-component fibre types are presented below in fig…….

a) sheath/core

b) Eccentric sheath/core c) side-by-

side

d) Pie wedge

e) hollowpie wedge

f) islands/sea

g) three islands

A modified cross-section can provide added functionality, such as unique lustre or moisture transport. These cross-sections are available in staple, filament and microfibre forms, and in most cases, are also available as bi-component fibres. Typical microfibres with special cross-section shape, commonly used, are presented in Figure - - -

a) hollow b) trilobal c) ribbon d) 4DG™

Figure -- Typical microfibres with special cross-section shape

Specialty Cross-Sections

Figure - Scanning electron microscope images of microfiber fibre

a) top view of microfibers b) cross-section of microfibre

b) SPLIT TYPEThe microfibres of this type are obtained by physically or chemically treating the bi-component filaments containing two types of polymers andsplitting them into different types of filaments.It is easier to split the segment in filament from itself than in the fabrics. Suitable polymer combinations for splittable bi-component filament spinning are polyamides/polyester and polyester/polyolefines.The main considerations for selecting the polymer combinations are as follows:

The polymers must be incompatible; The polymer should have reasonably similar melt viscosities at common extruder temperature; The polymers should have weak adhesivity.An example of a splittable fibre is presented in Figure-

Figure - Cross-sectional photomicrograph of a 16-segment splittable fibre

SOME OTHER METHODS

1. DIRECT SPUN METHOD2. SUPER-DRAWING TECHNIQUE3. SHEATH-CORE SPINNING METHOD4. FLASH-SPINNING METHOD5. SOLUTION FLASH-SPINNING6. EMULSION-SPINNING METHOD7. JET-SPINNING METHOD8. CENTRIFUGAL-SPINNING METHOD 9. TURBULENT FORMING METHOD10.CONJUGATE-SPINNING METHOD

PROCESSING OF

MICROFIBRES

Carding

It has so far proved impossible to card microfibres at productionrates which are comparable with conventional type of fibres,and So the cost per unit weight of production is much greater. In carding itis necessary to have a greater density of carding wire points.

Winding and warping

All guide surfaces must be very smooth and in the best mechanicalcondition, as microfilaments are likely to break more easily than regularfilament.

Sizing Warp sizing of microfibres should ideally be done on single-end sizing machines to minimise filament breakage at splitting rods. The size pick up on microfibre yarn is higher and it is also more desirable.

Weaving

Generally the tensions should be kept as low as possible. Weft yarn for air jet or water jet looms will need some finish to perform at maximum efficiency.

Dyeing of

polyester

microfibres

Due to their fineness, the total surface area of microfibre yarn or fabric is far greater than ordinary fibres. Threfore 

1. Due to its special structure ,micro fibers has much larger quantityof size ,oil agents and wax on warp yarns.2. Since microfibres have very small interstitces, with consequentdifficulties of size accessibility and duffusibility, desizing becomes quite difficult and costly.3. Microfibres have greater absorption area resulting in a dyeing ratefour times higher than that of normal, which can cause unlevelness in dyeing.4. They also require more dyestuff than standard fibres to obtain the same depth of shade. 5. Larger external surface means an increase in number of threads exposed to light which, on destruction of dye, is expressed as lower light fastness rating.6. Washing fastness and color fastness to rubbing is also poor.

Problems occcurs

The problems in wet processing of microfibers can be overcome by --

1. Better knowledge about the size applied and optimum parameters during desizing operation

2. Pre-setting

3. Alkali weight reduction

4. Careful selection of the dyes

Properties should be – i. Compatibleii. Having same exhaustion ratesiii. Having high washing fastness propertiesiv. Good migration and Levelling properties

5.Optimizing the dyebath conditions and dyeing cycle.

Optimized dyeing cycles can be worked out by controlling the temperature to account for the high rate of dyeing and to eliminate the risk of uneven dyeing. Chemicals and dyes to be added at, at least 10-20 °C lower temperature than normal polyester fiber dyeing. The additions of dyes must be progressive or devided at least into 4 parts. The heating rate must be slow from 40 deg C to 100 deg C. 10-20 min more holding time required at 130 deg C as compared to normal Polyester.

6. Proper selection of  Dyeing machinery.

7. Proper selection of dye bath additives such as 

Levelling agents :- A strong levelling agent which shall start working at lower temperatures

Dispersing agents :- Higher quantities of dispersing agents are needed because amount of dyes required are more to produce the desired depth

8. Proper after treatment of dyed goods

Soaping

Reduction clearing

Washing

General properties of microfibres

1) Light weight and Flexiable2) Good stability and Shape retention3) Anti-wrinkle property4) Have a wicking ability that permits perspiration5) Comfortable to wear6) Doesn’t water stain – Super water repellency is available7) Woven or knitted into a very high quality fabric construction8) Strong and durable, water repellent and wind resistant – so tightly woven ,that the fabric can’t be penetrated by wind, rain or cold9) Washable, dries quickly and also washable in at the water temp. up to 200°c and their characteristics will remain same.10) Electrostatic effect – hair, lint and other dust particles are attracted and grabbed by the microfibres without lifting dust.

General properties of microfibres

11) The density of the material allowable it to grip six to eight times its weight in water hence high absorbing power capacity.12) The attraction capability of the microfibers is so sound, even absorbs bacteria and germs - hence can be use as germ or bacteria free purpose.13) Comfortable - very soft, texture like silk, lightweight14) Due to its fineness and superior fiber surface area making deep, rich and bright colors achievable15) Less "sweaty" in warm weather than usual synthetics16) Quickly cleanable - clean just with water17) Change without help - to establish lovely drape18) Microfibres are environmentally friendly.

Applications of microfibres -

Fashion clothing textiles

High-performance filter fabrics

The characteristics of microfibre liquid filters are as follows: high water passage speed, high extraction performance (retention of particles up to micrometers dimensions), and ease of cleaning micro-particles from the filter.

Protection against the weather

Medical applications

Microfibres for cleaning

Microfibre products are suitable for cleaning anything. Unlike ordinary cleaning fabrics that move or push dirt and dust from one place to another, microfibres actually ‘scrape’ the dirt or stain from the surface, and then store the dirt particles in the fabric until it is washed. Microfibre cleaning clothes trap dirt and dust inside the cloth, and do not spread dust or dirt around. The user can clean the cloths with water alone; no chemicals are needed.

Some examples of general applications of microfibres

automotive application to improve air oil filtration, allowing improved engine performance and extended life perfect for asthma and allergy sufferers, removing dust mites without chemicals. used extensively for hair transplantation, which works to conceal thinning hair Microfibres are also used in sports applications such as sports wear, sports materials, etc Microfibres are extensively used as a luxurious apparel wear Microfibres as swing threads Microfibres for production of synthetic leather Computer mouse pads, along which the mouse can slide easily, keeping the mouse ball clean at the same time Polishing cloths for wafers and hard disks, acoustic insulation, high performance sound absorption panels and concert hall seat covers, among other products.

T H A N K Y O U