TRAINING MODULE

Introduction to textile fibres

• Textile fibres are the smallest unit which take the shape of yarns to fabric and ultimately to garments by application of intermediate processes. Textile fibres can be divided broadly into 2 groups namely natural fibres and man-made fibres. man-made fibres again can be divided into 2 groups namely regenerated cellulosic fibres and synthetic fibres.

TEXTILE FIBRES Natural Fibres Man-made Fibres

Cotton Fibres

Wool Regenerated Synthetic

Silk Cellulosic Fibres Fibres

Hemp

Abaca Viscose Polyester

Coir Cuprammonium Acrylic

Jute Modal Polypropylene

Flax Nylon

Cashmere Elastomeric

Mohair

NATURAL FIBRES Natural Fibres are those which can be obtained from natural

resources like cotton from cotton plants, wool from fleece of domesticated sheep, silk is a filament obtained from the silk breeding worms.

REGENERATED CELLULOSIC FIBRES Regenerated cellulosic fibres are man-made fibres which are

regenerated from the cellulose polymers. Viscose is regenerated from the wood pulp.

SYNTHETIC FIBRES Synthetic fibres and filaments are produced from a polymer made

up of long chain molecules by a succession of treatments using a combination of temperature, tension, pressure and residence time, for a given polymer, the arrangement of the chain molecules in the fibre is decided by a combination of process conditions that ,inturn,decide the thermal and mechanical properties of the yarn produced.Thus, fibres with different properties can be prepared from the same polymer by altering the spinning and drawing parametres or by a heat treatment The relationship between the process conditions and the fine structure of the fibres is of particular importance to the processor as well as to the producer of the fibres

SYNTHETIC FIBRES

FIBRE SPINNING RAW-MATERIAL Polyester Melt Spinning PTA + MEG

Nylon-6 Melt Spinning Caprolactam

Nylon-66 Melt Spinning Hexamethylene Diamine and Adipic acid

Acrylic Wet/Dry Spinning Acrylonitrile

Polypropylene Melt Spinning Propylene

Lycra Dry Spinning poly-ethylene glycol and toluene

2- 4 di-iso-cyanate

Aramid Dry-Spinning M-phenylenediamine and isophthaloyl

Chloride

Polyvinyl Alcohol Wet-Spinning Vinyl Acetate

Polyvinyl Chloride Wet Spinning Vinyl Chloride

Polyvinylidene Melt Spinning Vinylidene Chloride + Co-Monomer such

Chloride as vinyl chloride + Acrylonitrile

FIBRES USES PVC Filter Clothes, ropes, swim suits, industrial packing.

PVA Rain-coat , protective clothing's, umbrella cloth , surgical filter

Cloths , fishing nets.

Aramid (Nomex) Conveyor belts , cables , radial tyres , ropes.

Polyvinylidene chloride Insect screen , Filter Cloths , belts , suspenders , braids.

Lycra Foundations , Swim wears , Stretch Fabrics , Hosiery , Belts.

Polypropylene Carpets , Sports garments , bale covers.

Acrylic Sweaters , Knitting yarns.

Nylon Tyre-cords , shocks , ropes.

Polyester Apparel uses , construction , medical uses , home

Furnishings , paper industry , carpets , non-woven fabrics

An Introduction to synthetic fiber• Synthetic fibers are made up of polymers • As in case of any substances polymer is also

made up of many molecules, the difference is in their molecular weight in case of polymer the MACRO MOLECULES are present.

• The molecular weight of Macromolecules is in the range of 10000-40000 gm

• In case of polyester the molecular weight is in the range of 15000-20000 gm

• Polymer is made up of units called Monomer• For Polyester the Polymer is Polyethylene

terephthalate.

Degree of polymerization

• The length of the polymer chain is specified by the number of repeating units in the chain. This is called the degree of polymerization.

• In case of polyester the degree of polymerization is 80-100

Some basic definition related to the process:

• Catalyst: A substance ,compound or element –the presence of which influence the rate of a chemical reaction, but which remain chemically unchanged at the end of the reaction.

• Elasticity: The ability of a material or fibre to resume its original form,size or shape after forces which caused its deformation have been removed;the ability from stretch.

• Ester: The organic compound formed from the reaction between an alcohol and an organic acid .An Ester has the general formula R – COO – R , Where R in case of textile polymers, is a polymer radical.

• Hygroscopic: Describe the ability of a fibre or substance to absorb moisture from the substance.

• PH Scale : An acidity –alkalinity scale ranging from 1 to 14 . A PH of 1 is most acid ; and a PH of 14 is most alkaline. And a PH of 7 is neutral.

• Relative Humidity : It is the measurement of the amount of moisture or water vapour present in one cubic meter of air , expressed as percentage of the maximum amount of water vapour the one cubic meter of air could hold at the given temp.

• Tex : The mass in gram of 1000 mtr of fibre,filament, sliver,roving or yarn . It is the universal system of describing the linear density.

Polymerization

• Step Reaction (Condensation Polymerization) • Fiber, which are produced by condensation

polymerization are— 1) Polyester 2) Nylon

• Chain Reaction (Addition polymerization)• Fibre,which are produced by Addition polymerization1) Acrylic2) Polypropylene

Over-View on the different spinning methods

• Melt Spinning : As the name indicate the polymer extruding through the spinnerette is in the molten form .

• An essential requirement for melt spinning process is that the polymer should not be volatile or decompose in the molten state

• Melt spinning process can be devided in to three steps -a) Shear flow of the spinning fluid within the spinnerette channel.b) Transition zone between shear and elongation flow ; In this zone

the fluid polymer can increase its dia (Barus effect).c) Elongation of the fluid jet under the external tensile force applied

by the winding up device.d) The fluid jet is transformed in to the solid fiber during the last step.

• Melt spinning was first used for the preparation of Nylon 66• Three commercially important textile fiber are produced by the

melt spinning process

FLOW DIG OF FILAMENT YARN PRODUCTION

DMT OR PTAAND MEG+ADDITIVES

PTA & MEG+ ADDITIVES ESTERIFICATION

POLYCONDENSATION

CHIPS PREPARATION

MELT SPINNINGPOY

DRAW- TEXTURING

DRYING OF CHIPS

FLOW DIG OF POLYESTER STAPLE FIBRE PRODUCTION

PPTA&MEG+ADDITIVES

ESTERIFICATION

POLYCONDENSATION

CHIPSPREPARATION

DRYING OFCHIPS

MELTSPINNING

STRETCHINGHEAT SETTINGCRIMPINGDRYINGCUTTINGBALING

TO TEXTILEMILLS

FLOW DIGRAM OF SPINNING LINE

FILAMENT FROM SPINNERET

QUENCH

CHAMBER

RING OILER PENCIL

GUIDE

SLOT OILER

V-GUIDESUCCER/CUTTER

DEFLECTORGODDETS

GODDET

ROLLERS

CAPSTAIN

UNIT

Wet Spinning• spinning dope is extruded through spinnerette holes and

bought in contact with the coagulation bath, The polymer in the dope is coagulated in to individual filaments,

• The bundle of such continuous filaments also called tow may be combined with the tow coming from other parallel spinnerette and are taken on the first set of take up roller

• These tow are then passed through the boiling water containing neutralizing and surface active agents, to remove the solvent and to stablise the fiber end groups. In the subsequent steps of processing the tow is stretched, thoroughly washed,lubricated,dried ,steam conditioned ,crimped, autoclaved for heat setting, and finally cut in to the staple fibre.

• There are mainly two types of spinnerette (1) Pan shaped spinnerettes accomodating 25000-75000 holes and (2) Spinneret element assemblies accomodating up to 1,20,000 holes in an assembly of 55 spinneret element

•Each spinneret hole has a concave entry portion , followed by a circular capillaryWith a small L/D ratio Hole dia ranges from .05 to .5mm, The pattern of the spinneretHole distribution are designed in such a way that the coagulation liquor penetratesThe filament bundles entirely.

Preparation of Dope: Polymer solution in an appropriate solvent is used in both theWet and Dry spinning processes .There are many things common in the process ofPreparation of the spinning solution for both the spinning processes. With inorganicSolvent ,the wet polymer cake is dissolved directly , while in the case of organic Solvent , thoroughly dried polymer powder is used .Dissolving polymer powder in the Solvent is a tricky process and require utmost care. The polymer is mixed with DMFOr Dimethyl acetamide under vigorous stirring condition to obtain polymer slurry,At very low temp (0-5 deg cent) which is then heated (80-90 deg cent) by passing Through heat exchanger to get clear solution . Additives often added to get the Special properties on the fiber .

COAGULATION : Coagulation is generally brought through solvent-non solvent Diffusional interchange between the spinning dope and the coagulation medium,Solvent leave while non solvent enters the polymer phase. After sufficient time No more exchange takes place and a stage of equillibrium is achieved For a givenPolymer and solvent system , the final equillibrium state is always governed by theComposition of the coagulation bath and the temp at which coagulation occurs.

The important Coagulation and spinning variables directly related to the fiber Formation are as follow…..

• Spinning Dope Concentration

•Coagulation bath temperature

•Coagulation bath concentration

•Coagulation bath PH

•Jet stretch ratio

•Stretching and washing bath temp

•Stretch ratio

•Stretching speed

Dry Spinning In a dry spinning process the spinning assembly with the spinning

pumps,filteration system and spinneret heads are located on the upper level of spinning tower .A relatively more concentrated spinning solution than wet spinning process is required in this process in order to evaporate the solvent rapidly Immediately below spinnerette,mounting in the spinning chamber ,preheated inert gas is blown on to the forming filaments through circular jet system. Special attention is given to avoid the possible turbulence in the gas flow so that filaments do not touch each other prematurely and fuse.

The oxygen content of the spinning gas sent in to the column is also carefully checked to minimize discoloration in the fibre .

The spinnerette with varying number of holes from 300-900 is used in the process .The spinning chamber consist of vertical jacketed cell .The spinning speed used in the process is of the order of 200-500m/min . In some processes the pre heated gas ,enters at the top of the jacketed cell ,flows downward with the filament and exits to solvent recovery near the bottom of the cell. While in some processes the pre heated gas is fed in counter current to the filaments which is emerging through the number of fine holes. Inlet inert gas temp varies over the range of 100-2500C depending on the nature of polymer and solvent .Fibre formation occur as the filaments are drawn through the spinning chamber and solvent gradually vapourises.The dry spinning process allows the spinning dope to be kept at higher temp ,making possible high concentration of the order of 25-35% and this in turn is responsible for a high level of liquid crystallinity leading to good molecular orientation in spinning.

Comparison between wet spinning and dry spinning process

Parameters Wet spinning Dry spinning

1) Investment cost Low High

2) Hazard Toxic Toxic and involve risk of

explosion

3) Heat input in spinning Low Very High

4) Spinning dope conc 20-28% 25-35%

5) Cross Section Round or Dog bone shape

Beam shape

6) Spinneret holes 20,000-75,000 300-900

MELT SPINNING EQUIPMENT

• The various melt spinning equipments are as follow—

1. Extruder

2. Static Mixer

3. Manifold

4. Spin pack

5. Spinneret

6. Quenching Chamber

7. Spin finish application

8. Intermingling in case of POY

9. Take up unit

EXTRUDER : The most widely device for melting and mixing of polymer chipsIs extruder. Essentially ,an extruder is a pump in that it is designed to supply A continuous stream of molten material .Material is fed in to the extruder ,ItIs then heated and compressed with in the extruder until it becomes a homogenerous uniform melt. The heart of an extruder is the polymer screw. Fitted Tightly

STATIC MIXER : When the polymer comes either from extruder or booster Pump there is substantial temp difference between of the melt near the wallOf the polymer line and at its centre. Such a big difference in temp will lead To the production of yarn with non uniform characteristic. Thus Static mixer Are provided to over come this problem

MANIFOLD : After filtration, the polymer melt is passed through the manifoldOr spin beam which divides a molten polymer stream in to many equal streamsAnd meters these streams through filter and spinneret to form synthetic fibersAn essential requirement of manifold is to maintain all the polymer stream atThe same temp and preferably to give equal residence time for each stream .If the residence time varies from position to position, so will be polymer molec-ular weight and therefore the viscosity.

SPIN PACK : The manifold deliver the polymer melt to the spin pack assemblyFixed at each spinning position. The spin pack assembly consists of machineElement to accomplish filteration and/or shearing of molten polymer stream.At the end of spin pack assembly spinneret is fixed for melt extrusion .The spin pack is a pressure vessel and is therefore subjected to high stressesAnd leakage problems common to the pressure vessel

SPINNERET: Spinneret is the most important part of the a spinning machine It is relatively small disk filled with many tiny holes . The disk is usually circularIn shape. The circular spinneret holes are slightly wider at the entry than the exit.

QUENCHING CHAMBER : The polymer coming through the spinneret bulgesSlightly to release the pressure and is then drawn off from the bottom,In order to get a good even yarn the output of the cross air must be constant and Uniform , without creating whirling motion around the yarns, which can lead to theVariation in yarn dia

SPIN FINISH APPLICATION : The Spin finish is applied to the quenched filamentsBefore they are wound up in to bobbins or passes through the pair of goddet rollersTo form tow. The function of spin finish is to afford to the yarn low frictional properties,to assist the drawing and winding operation, to confer antistatic protection.

Raw Material for POLYESTER• PTA (Pure Terephthalic acid)• MEG(Mono Ethylene Glycol)

PTA :It is produced from p-xylene,This process is based on catalytic oxidation of p-xylene, In this process p-xylene is converted to PTA by reaction with pure gaseous oxygen in acetic acid solvent at 1300C.Cobaltous acetate is used as catalyst and methylethyl ketone as the catalyst activator. The yield at this stage is around 98% on p-xylene

MEG: The other raw material is monoethylene glycol which is

produced by the oxidation of ethylene in the presence of air to get ethylene oxide which is absorbed in water to get monoethylene glycol. The on more process is acetoxylation process ,In this process ethylene is reacted with acetic acid and oxygen to obtain glycol acetate which are then hydolysed to monoethylene glycol . This process has an ethylene efficiency of 90%

The PET Polymer preparation • The PET Polymer preparation is a two step process • Esterification and the second step being Polycondensation Esterification Reaction: PTA and MEG are to be taken in the ratio of 1:1.5 to

1:1.8 For PTA Process it is usual practice to keep some quantity of DGT from earlier batch in the esterification vessel to get better solubility of PTA It also helps in increasing rate of esterification.

Polycondensation Reaction : After Esterification The polycondensation reaction is carried out in presence of catalyst such as antimony trioxide or antimony tri acetate. As the Temp and reation time increases the degree of polymerization also increases. But it can be seen that DP increases considerably when the temp is raised from 275 to 2850C The reaction velocity increases ten fold when the temp is raised from 240 to 2800C Raising the temp above 2800C only exerts a slight influence on reaction velocity and in general does not have a favorable effect on the characteristic of polycondensate. During the polymerization DEG formation takes place and DEG is not likely to be immediately removed from the reaction mixtureby distillation because it is rather high boiling point .

Thus Polyester is essentially a copolymer having DEG units occuring in between poly units.

Factors Promoting the formation of DEG in PET

• Low rate of esterification of PTA promote the formation of DEG in PET

• Formation of DEG is generally higher at lower PH (The PTA being acidic promote the formation of DEG)

Effect of DEG on polymer and fibre properties• The melting point of polymer is lowered and polymer will melt

over a broader range of temp ,an increase in 1% of DEG content will lower the melting point by 50C

• It will lead breakage during melt spinning .• Dyeing rate increases with the increase in DEG content • The tensile strength of fibre is lowered with increase in DEG

content• Fibre having high DEG content reduces resistance to light.

COOHHOOC + HO(CH2)2OH

HO(CH2)2OOC COO(CH2)2OOC COO(CH2)2OH +H2O

THE CHEMICAL REACTION FOR PET PREPARATION

Esterified Product

Here Also the major esterified product is DGT in which case x=0, The second stage Of preparation of PET Polymer is called polycondensation and is similar for bothDMT and PTA routes.In the polycondensation process DGT containing some quantity of dimer,trimerAnd tetramer is heated at high temp and under vacuum to get PET with the Liberation of MEG.

PTA MEG

n HOCH2CH2OOC COOCH2CH2OOC COOCH2CH2OH

COO(CH2)2OOCHOOC(CH2)2OOCnCOO(CH2)2OH

PET

+HO(CH2)2OH

Catalyst and Semi dull agent

• Antimony Trioxide(Sb2O3) used as a catalyst, the role of catalyst is to increase the rate of reaction without effecting the chemical reaction. Catalyst slurry is prepared with glycol 2% Sb2O3 slurry is prepared and is added during the beginning of the paste preparation of PTA+MEG.

• TiO2 is used to give the semi dull effect to the fibre in the final stage of fibre TiO2 present in 0.20-0.30%

Stretching or Drawing• Synthetic fibre produced by melt spinning or wet or dry spinning

processes have very high extensibility values and low strength and are therefore unsuitable for textile use

• The stretching or drawing of synthetic fibres is carried out to reduce the elongation and to increase the strength to a desired level

• During stretching both the crystallinity and orientation increases

• Stretching (Drawing) also stabilizes the filament to the physical, chemical or atmospheric influence.

• Thus it is important to choose proper drawing condition for the desired fibre properties.

These includes---- 1) Draw ratio 2) Draw speed 3) Draw Temp

Heat Setting• The event that occur in heat setting process

can be summarized in the following three stage

1) Weakening the intermolecular links in the fibre and increasing the mobility of its structure elements by raising its temp.

2) Formation of more even structure as a result of thermal relaxation and reduction of internal stresses and

3) Stabilization of the even structure by reformation of bonds in an energetically favorable configuration usually it is attained by sharply cooling the yarn

CRYSTALLINITY & ORIENTATION• The fine physical structure of synthetic fibres based on an amorphous-

crystalline, two or three phase module is now universally accepted• The elongation at break gradually decreases with the winding speed and

the orientation and in turn the modulus increases with the speed• Crystallinity of PET increases with the heat setting temp under relaxed

condition or taut condition ( with tension)• In case of synthetic fibres it is often possible to control the degree of

orientation by applying a stretch of desired intensity to the spun filaments.• There are two types of orientation present in the synthetic fibres-a) Crystalline orientationb) Amorphous orientation Birefringence measure the orientation in both the crystalline and amorphous

domains BIREFRINGENCE: It is the difference in refractive index along parallel and

perpendicular to the fibre axis. Birefringence is the measure of the degree of orientation of the molecules. The birefringence of the undrawn yarn is very low, which confirms that the molecules are not highly oriented , if a fibre consisting of randomly arranged molecules is stretched , the molecules tend to orient themselves in the direction of stretching . Thus the birefringence of the fibre increases on stretching.

Molecular Structure and Tg• The glass transition temp may be defined as the temp

below which the amorphous polymer is glassy and above which it is rubbery

• The Tg of the fibre is influenced by its crystallinity, crystal size,& orientation

• For ex the Tg of PET fibre increases with crystallinity from 80-120oC

• The amorphous PET chips soften and stick together if they are heated together at 100-120oC on crystallization the same chips do not soften even at 170oC

Fibre Line Process

Fibre line is a place where the actual fibre is born after passing through several processes .The cables which are collected in the cans are transported to the creel area of the fibre-line with the help of the transporter. No of cans in the creel area depends on the tow denier to be fed in the crimper or better to say the no of filaments per cm is calculated and on that basis the no of cans are decided for a particular denier.

CREEL AREA

The ends of the cable are pulled out of the cans and then it passes through guide roller and buffalo horn to the eye-guides placed in the creel area and finally to the eye guides placed in the 0-mtr floor. Creel area is divided into two parts left halve and right halve each accommodating a maximum of 14 cans. The cans are placed after dividing the cumulative no of positions into 2 parts (as per theory). The cables are then divided into 3 parts consisting of 25%,50% and then again 25%.The resulting form is called tow. Various sensors are used in the creel area to detect the faults in the cable.

• Loose end detector.• Tight end detector.• Knot detector.

The sensors are provided to sense the faults in the cable and stops the line if required. The further processes of the Draw-line are as follows.

TGF Dip-Bath DF1 DF-II HCA TSU Tow-Cooler

HC-B Tension Roller TCU

Crimper Dryer Cutter

conveyor belt

The different machine parts of Draw-line have different functions to control the fibre properties , runnability and final attenuation to desired fibre denier.

TGF

The full form of TGF is Tow Guiding frame it consists of 7 rollers which are rotated at speed such that the whole tow becomes taut and can be further useful for dipping and drawing.

DIP-BATH

The main function of dip bath is to wash out the spin finish already applied on the cables in the spinning.

DF-I AND DF-II

The use of draw-frame-I is for drawing the fibres and a specified draw ratio is given to stretch the filaments between DF-I and DF-II which is called Neck drawing. The draw-ratio is set by the difference in the surface speeds of the rollers.

HEATING CHANNEL

The function of heating channel is to decrease the temperature gradient the temperature in the DF-II is around 750C and the temperature in TSU is around 1800C .To minimise the temperature difference or gradient at pressure of 1.1bar pressure flush steam is applied and 2.0bar of coil steam is applied.Again this stage is important to reduce the breakage level and also make the fibre pliable for further drawing.

THERMOSETTING UNIT

In fleissner latest lines the TSU is of 18 rollers divided into 3 drive zones of 6 rollers each and 4 steam zones of 6,4,4,4 rollers traced backwardly from last to first. The 1st steam zone is given a pressure of around 16-18bar and the 2nd and 3rd zones are having a differential of 1bar each. from drive point of view, The 1st zone is having the highest speed which is also called line speed. In between DF-II and TSU-I draw-ratio of around 1.015 to 1.200 is maintained for stretching the filaments this is also called taper drawing. The successive zones are given a relaxation effect for more residence time and that the properties are achieved under relaxed conditions.TSU is a place where the stretching is completed and filament of required denier is formed.Here also the strength is imparted by annealing the filaments by passing them under tension on rest of the 12 steam heated cylinders at temperatures 195 to 220.

TOW COOLER

The spin finish is sprayed onto the tow through a series of nozzles which is 16 in all 8 at the top and 8 at the bottom. The main function of the tow cooler is to freeze the properties whatever achieved in the TSU zone.

TOW CONVERGENCE UNIT

The tow is divided at this place into 3 parts and the 2 parts of 25% tow each is overlapped with the 50% tow. The overlapped tow is then fed to the crimper after passing through tension roller and Heating channel-B.HC-B is provided to raise the temperature of the tow upto 100 for making the fibres pliable for crimping.

CRIMPER

The crimper is the part of the machine where the crimps are imparted onto the filaments.It has two parts nipping rollers and stuffer box. The roller are given to feed the tow and the stuffer box is provided to impart crimps in the tow. Crimps are generally of type:

1. primary crimps

2. secondary crimps.

DRYER

The dryer is generally divided into 4 steam zones to maintain a temperature from 65 to 95 to dry the wet tow. the tow is guided to the cutter and the cut fibres are baled for despatch.

CUTTER The cutter is a reel having slots at intervals equal to the

cut length desired 32/38/44/51/60. The cut fibres fall down by gravity and is usually partially opened by several air

FIBRE SPECIFICATIONS

DENIER:

Usually the actual denier is a little on the finer side i:e for 1.2d it is 1.16 to 1.18 for 1.4d it is around 1.35 to 1.38.The tolerance is normally is +/- 0.05 and CV% of denier should be 4-5%.Denier specifies the fineness of a fibre and in a way controls the spinning limit. Theory tells us that in order to form yarn on ring frame there must be 60-62 fibres in the yarn cross section. The limit for 38mm fibres are shown in the table limit rises for higher cut lengths.

DENIER COUNT(Ne)

1.0 60-70

1.2 40-60

1.4 30-40

2.0 20-30

3.0 Below 10

CUT LENGTH CL available are 32,38,44,51 and 60mm for textile grade fibres

for specialised fibres CL of 3mm,6mm,12mm,102mm and 204mm is also available. For blending with other man-made fibres,spinners preferred 51mm to get higher productivity, because the TM will be as low as 2.7 to 2.8 as against 3.4 to 3.5 for 38mm fibre.If the fibre cut length is more, the nepping tendency is also more, so a compromise cut length is 44mm.With this cut length the TM will be around 2.9 to 3.0 and yarns 35 to 40% lower imperfections can be achieved compared to similar yarn with 51mm cut length.

For open end spinning , 32mm fibre is preferred as it enables smaller dia rotor of 38mm to be used which can run at 80000 to 100000rpm.

Different Properties Of Filament yarns/Staple fibre

• A number of tests are performed to check the quality of filament yarns and staple fibres some of the important tests are as following---

For Filament Yarn For Fibre1. Denier Denier2. Draw Force %Elongation3. %Elongation Tenacity4. Tenacity Cut length5. U% T10 Value6. %OPU % OPU7. Nips AF/DDD/TF8. Bulk Density9. CN/CI/CS10. EYS( OFUDY)11. NDR(OF UDY)12. Spun Denier (OF UDY)13. % Moisture (OF UDY)

Influence of product parameters on product properties

CH

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DE

NIE

R

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NA

CIT

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EL

ON

GA

TIO

N

T 1

0

SH

RIN

KA

GE

DY

EB

ILIT

Y

CR

IMP

S

CR

IMP

S E

LA

ST

ICIT

Y

DR

AW

PO

INT

DR

AW

RA

TIO

VISCOSITY - - - - -

THRUPUT - - - -

SPINNING SPEED - - - -

SPINNING TEMP - - - - -

QUENCH AIR - - - - - - - - - -

DRAWING SPEED - - - - - - - - -

DRAW RATIO

THERMOSETTING TEMP - - -

DF-3 TEMP - - - - - - - - -

STEAM BOX PRESSUSRE - - - - -

CRIMPER GATE PRESSURE - - - - - - - -

DRYER TEMP. - - - - - - -

DRYER BELT SPEED - - - - - - - - -

FIB

RE

LIN

ES

PIN

NIN

GPROCESS PARAMETER

Increase in parameter –

Decrease in parameter –

Main Control parameters -

No significant impact - -

Detail discussion of different properties of fibre and their importance

• Denier: Denier is the weight of 9000mtr length of yarn/fibre in grams, it can be controlled by altering the through put in spinning .Different den which are spun ,most commonly are .0.8/1.0/1.1/1.2&1.4

• Elongation: Elongation is expressed in % ,This property is important for the staple fibres to be blended with cotton or viscous. Its value ranges from 19.0-22.0% for fibre of different denier.It is controlled mainly by IV,Spinning Temp&draw ratio

• Tenacity : Tenacity is the measure of tensile strength of the textile fibre , Polyester filaments and staple fibres are strong to very strong because of their extreamly crystalline polymer system.It is expressed

in gpd (gram per denier) , the value is around 6.4-6.7gpd• Dyeability : The dyeing properties of synthetic fibres are greatly influenced

by the crystallanity and orientation of the fibre. The dyeability of staple fibres should be checked regularly using suitable dyes. The dyeability of staple fibre can be adjusted by adjusting the temp of TSU (Thermosetting unit) It is expressed in % it should be close to 100%

• %OPU : In Staple fibres the %opu is of utmost important the value of this should be optimum i.e neither it should more nor less than the required value. For higher cut length fibre more OPU is required than lesser one. It ranges from .0165-.185% depending on CL of the fibre

CRIMPS : The Crimp measurement from time to time is very important, inspite of Measurement it should be in practice to check regularly the crimps immediately After coming from crimper.The variation in crimps will lead to the generation of OLF( Over length fibre) .For this the Crimper nip roll pressure should be optimum And the width of the tow should be as per the norms (350/700/350mm)

ABNORMAL FIBRE: The abnormal fibres are measured in mg per 100gmOf the sample and it should be below 5mg . Once the AF problem arisesIt is difficult to control thus care should be taken in spinning the problemMay be due to the following reason ---• Insufficient supply in quench air.• Air leakage from bellow.• Turbulence in air flow.

BULK DENSITY: This is the measure of the bulkiness of the fibre which isUseful while opening and mixing with other type of fibres the value comes Around 300cc (sample wt=40gm)

An Introduction to spun yarn • Spun yarn are produced by placing a series of individual

fibres together to form a continuous assembly of overlapping fibres, usually bound together by twist.

Terminology of spun yarn:Yarn Count: 1) Mass per unit length.This is known as the direct method

where a higher count number denotes a thicker yarn2) Length per unit of mass . This is known as the Indirect

method ,A higher count number denotes a thinner yarn. It is important to realize that yarn dia is related to Yarn count , either directly in the case of direct count

system or inversely for the indirect count system.

Flow dig of spun yarn manufacturing

OPENING &CLEANING

BLENDING &MIXING

HCARDING DRAFTING& DOUBLING

AUTOLEVELLING

COMBING

(OPTIONAL)

TO SPEED-

FRAME

TO RING FRAME

EXPLANATION• Opening and cleaning: The bales which is in

the compact form need to open for further processing in the spun yarn unit.

• Blow room opening and cleaning lines: Cleaning lines consists of from One beating points for synthetics up to about seven beating points for low grade cottons with trash contents exceeding about 3.0%

• For Polyester /Viscous ½ beating point is used• The minimum amount of beating to give sufficient

opening is desirable.

BLENDING AND MIXING: The basic objective of fibre blending is to get the desiredProperties in the yarn. Polyester being low moisture regain need to blend with cottonWhere moisture absorbency is required .On the other hand we can say that cotton Having less tensile property need to blend with polyester to improve its strength.

CARDING: There are four main carding objectives, they are:1) To separate each fibre from the others in each original tuft of feed material with a minimum of fibre breakage.2) To remove impurities and fibre entanglements3) To mix the fibres together to provide a uniform distribution4) To form a bulky sliver of overlapping, partially aligned fibres

DRAFTING AND DOUBLING: The use of draft gives a reduction of sliver thicknessAnd also contributes to improve fibre orientation when processing card sliver.The sliver fed together in to a drafting zone are called doublings. In yarn manufactureIt is correct to refer not only to two doublings , but also to three, four…,theoreticallyUp to any number of doublings, although in practice there will be an upper limit Imposed by the capacity of any given machine

THE USE OF DOUBLING SERVE THREE PURPOSES:1) Reduce Irregularity : In general the coefficient of variation of count of combined Sliver is less than that of each individual sliver.

2 Blending and mixing: The use of repeated drafting and doubling ensures that theEnd product is a homogeneous mixture.

3) Fibre alignment : The use of doublings necessitates a greater total draft productIn order to obtain a given amount of reduction of sliver thickness. The higher totalDraft product applied to thicker slivers thereby contributes to better fibre parallelizationAnd hook removal in an uncombed sliver, which usually implies greater yarn strengthAnd better yarn levelness.

COMBINATION OF DRAFT AND DOUBLING : There are three possible basic Relationshp-1)Doubling draft2)Doubling = draft3)Doubling draftThe first of these is only used where mixing is of prime importance. The second is usedWhere mixing is important but an increased sliver thickness must be avoidedThe third arrangement is used to obtain a reduction of count, the rate of reduction Being dependent on the ratio draft/doublings. This ratio is frequently increased towardsThe latter part of a drawing set immediately prior to spinning.

AUTOLEVELLING: The object of an autoleveller is to measure the sliver thicknessVariations and then continuously to alter the draft accordingly so that more draft Is applied to thick places and less to thin places with the result that the sliver deliveredIs less irregular than it otherwise would have been. Besides an improvement in Product appearance, autolevelling can also contribute to better productive efficiency,Fewer end breakages in subsequent processes, less waste and constant processCondition .

COMBING: The basic objectives of combing are

• Removal of short fibres.

• Removal of non fibrous impurities which may be called trash, and imperfections such as neps and slubs.

3) Straightening and parallelization of the long fibres which are retained.

The combing operation may be used to enable the ultimate yarn to be smoother,Finer,stronger,and more uniform than otherwise would be possible.Remember : Combing is done in case of cotton fibres only

THE SPINNING PROCESS: Although spinning is only one single process in theSequence of operations require to produce a staple fibre yarn ,It is an expensive one Require much more floor space ,power and labour than all the drawing operations Combined.

The spinning process consist of basically three stages:

1) Reduction of strand thickness from the supply roving to the required yarn count. This is usually done by roller drafting with some mean of fibre control such as doubling apron but a different arrangement is used in rotor spinning and in mule spinning. It is important that correct yarn count is produced because there is no subsequent opportunity for correcting any mistakes in this respect.

2) The prevention of further fibre slippage, usually by twist insertion

3) Winding on to a package which is convenient for handling and which protect the yarn.

Properties Effect in Spun Yarn processing

Tenacity Yarn strength and count strength product [ CSP] affected , The lower Tenacity will lead more breakages in ring frame.

ElongationElongation and Tenacity are co-related properties, thus the higher elongation will cause the

same effect as which is due to the lower Tenacity.

% OPU

The Oil pick up in fibre is of utmost importance as it directly influence the uniformity of yarn. The low OPU % will give rise to the low inter fibre cohesion And thus having roller lapping chances during carding operation, will lead to web

sagging also.

Crimps

Crimps number and crimp elasticity play a very important role To maintain the yarn uniformity The low crimps will cause the non uniform drafting due to low inter fibre cohesion and

will affect the CSP of yarn also.

Shrinkages [DHS]

The % shrinkage of yarn is important where bulkiness in yarn is required. It affects the productivity also if the shrinkage increase above the limit will slow down

the productivity.

Fused fibre / PlasticDuring processing of Spun yarn plastic / fused fibre will lead - The damaging of Card wire / licker in wire and may also cause the card jamming

OLF / MLF It will have significant effect on yarn uniformity Uneven drafting and short fibre generation during drafting process.

EFFECT OF FIBRE PROPERTIES ON SPUN YARN PROCESSING