Introduction to Textile Processing for Non Tech

8/8/2019 Introduction to Textile Processing for Non Tech

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Why we need FURTHER

PROCESSINGy Textile fabrics, just after the

Fabric formation- weaving, knittingetc. do not satisfy requirement fora particular end use.

y Textile processing attributes thefinal performance or aestheticneeds.


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MA TERIAL FOR TEXTILEPROCESSING

y G ray material coming for textile processing couldtake various forms like

1. Loose fiber2. Yarn in cone, cheese or Hank form3. Fabric either woven, knitted or any other form of interlacingDepending on nature of the raw material, various forms of

machines as well as processing methods have to be used. we will consider mainly processing of Important fibers like

Cellulosic ( specially Cotton), Polyester and - woven/ knitted,material, and very briefly other fibers and blends.


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TEXTILE PROCESSING Processsequence

GRAY FABRIC

DIRECT USE(e.g.Handloom Cloth )

CHEMICAL PROCESSING

PHIYSICAL CLEANING +CHEMICAL PROCESSING


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PHYSICAL CLEA NINGy Physical cleaning , like shearing & cropping and is done

to remove extra pieces of yarn hanging from the fabricsurface.

y

Singeing removes fibers protruding from the surface.y Brushing is used in both processes to loosen the added

material like sizes, from the fabric surface.

Shearing @ CROPPPING BRUSHING SINGEING


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PHYSICAL CLEA NING - Singeingy Singeing is a processing step that removes surface

fibers from woven fabric and not needed for knitted

goods.y These surface fibers form small fiber balls on the cloth

after being washed several times ( Pilling).y Many different systems are available for Sineing but

usually G as Singeing is common where the goods passthrough gas-fired burners at a high speed. For wovenmaterials, this is the first processing step.


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Gas Singeing M achine


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CHEM ICAL PROCESSINGy 1. PRETREATMENT

DESIZING SCOURING BLEACHING

MERCERIZING

WOVEN CLOTH Knitted cloth


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PROCESSING COTTONy First step of wet processing is to remove all the impurities

either natural occurring ( in Natural fibers) or man made ( inman made fiber).

y

Natural impurities include waxes, oils, proteins, mineral matterand residuals seeds. And in addition, Cotton contains asignificant amount of contaminants resulting from the widespread useof fertilizers, insecticides and fungicides.

y Previous spinning, knitting or weaving processes leave

residuals of knitting oils and sizing chemicals on the surface of the natural and man made fibers. All these impurities must beremoved before dyeing, because they can interfere with thedyeing process.

y Insufficient preparation can result in an uneven dyeing, cancause potting or can even damage the fabric permanently.


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Sizingy During sizing, chemicals are applied to the yam before

the production of a woven fabric. Substances such as

starch, polyvinyl alcohol (PVA), polyvinyl acetate,carboxymethyl cellulose (CMC) and gums enhancethe tensile strength and smoothness of the warp yarnso it can withstand the mechanical forces during

weaving.y Yarn used for the production of knitted fabric areusually treated with waxes or lubricants


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D esizingy After the weaving process, the sizes have to be

removed from the fabric because they interfere withsubsequent processing steps.

y Three methods frequently used in textile processingare Acid desizing,Enzyme desizing, andOxidative desizing.

The goal of these different methods is to hydrolyze thestarch, and conevert them to water soluble sugars.


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Scouringy Scouring is typically performed in an alkaline solution

and high temperature environment. The removal of natural impurities is based upon saponification at high

pH.y The removal of natural impurities can be done in a

single process or can be combined with desizingand/or bleaching.

y Scouring is usually the first step in the processing of knitted goods and will remove the knitting oils which

were applied to the yarn prior to knitting.y There is modern environmentally freindly, enzyme

process also available today.


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Bl eachingy Almost all fabric are being bleached to remove the

natural coloured matter.y

Chemicals commonly used: hydrogen peroxide,sodium hypochlorite and sodium chlorite.y After Chlorine bleaching, the goods are washed and

treated with antichlor (NaHSO3) to remove any traces

of Chlorine.y Hydrogen peroxide bleaching is carried out under

alkaline conditions. As a result, scouring and peroxidebleaching can often be conducted in one step.


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M ercerizationy Mercerization is the treatment of pure cotton fabrics

or yarn with a strong caustic soda solution to improve

strength,y dye substantivity,y absorbency y and smoothness and lustery Sufficient washing is required after this step to remove

any traces of caustic soda


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D YEINGEXHAUST

APPLICATION

PAD APPLICATION PAD MANGLE

HEATFIXATION

STEAMING

ColdBATCHING

WASHING

Jigger

WINCH

JET

SOFT Flow


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M odern Jiggers


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D YEING WINCHES


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Jet D yeing M achine


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B eam D yeing MA chine


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Pad Steam range


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D YEINGy Dyes can be divided into number of classes based on

their method of application.y DIRECT dyes are kept loosely by week attractive forces.y Reactive dyes are anionic dyes that form covalent

bonds with the hydroxyl groups in the cellulose.y Acid dyes contain sulfonic groups are used to dye SILK,

Nylon and wool.These dyes are rarely used in cotton dyeing.

. Mordant dyes are acid dyes Which are reacted with ametal salt prior to dyeing.


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Selection of D yesy There are number of Criteria to select a suitable dye

for a dyeing process. They arey

1. Type of fibery 2. Type of Machine availabley 3. Fastness properties needed.y 4.COST


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D YEINGCOTTON and Other Cellulosic fibers:

y Direct dyes: Easy dyeing poor wash fastness and Light

fastness but could be improved a little. AZO Bann Appliesy REACTIVE:G ood wash Fastness, G ood light fastness (

Except some reds)y VAT: Very G ood over all fastness. Costly y Naphthols: Not in use. AZO bann applies


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D YEINGThe second class of dyes needs chemical reaction before

application.y

Vat dyes are soluble in their reduced form. They aremade insoluble by oxidation after they are applied toorganic fibers.

y Sulfur dyes are also made insoluble through oxidation.


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D YEINGy The third dye class are special dyes such as

disperse dyes used for Polyester, and natural dyes and

pigments.Disperse dyes are water insoluble ( Sparingly soluble)and are used for most synthetic fibers.

. Pigments are set to the fabric by an adhesive ( Binder).


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FA STNESS RATINGy Fastness to LI G HT is measured on the BLUE SCALE

with following ratings:

1. Poor2. very bad3. bad4. Fair5. G ood6. Very G ood7. Excellent

8. Unsurpassable.


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y Fastness to other media is measured on the two G RAY SCALES ( Effect & Stain) with following ratings:

1. Very Bad2. bad3. Fair4. G ood5. Very G ood


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D YEING POLYESTERy Only Dispersed dyes.y Limited application of Vat and Pigments.y Problems with Sublimation and Thermomigrationy G ood wash and light and Rub fastness.


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Poly A mide , Wool and Silky Acid dyes: Bright colours, good light and washand rub

fastnessy

Basic dyes: Very bright shades . Poor Light fastnessy Wool and silk could be dyed with reactive dyes as well.


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D YEINGM ETHOD Sy Like pretreatment, dyeing can be done in the batch or

continuous mode.y

Continuous dyeing is carried out by passing the fabricthrough a dyebath of sufficient length. The dye is thenfixed onto the fabric by steaming. Subsequently, thefabric is washed to remove excess dye.

y

Batch processes include beam, package, jig, and jetdyeing.Pad-batch dyeing is a specialized technique for theapplication of reactive dyes to cellulosic fibers


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What is Textile Printing ?

y It is application of colorants to alocalized area, on a textile

substrate.


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What are the Printing methods?W e have following methods, as mostsuitable methods for textile printing.

1. Block printing2. Roller printing 3. Flat Bed printing#4. Rotary screen Printing5. Transfer printing6. Digital printing


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PRINTINGy In printing, the print paste is very thick and viscous to

prevent the migration of the dye in the fabric. Thismakes it possible to create a pattern of colours on thefabric.

y The paste is transferred onto the fabric using a rotary screen, flat screen or engraved rolls.

y Other printing techniques use heat to transfer the dye

to the fabric.y When the different colours are applied to the fabric, it

is dried at high temperature to set the colors on thefabric


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Printing stylesy Direct : Printing of all colours in the design, one

by one directly to fabric.y Discharge: Decolourisation of a printed area

or a dyed back ground colour, by printing a reductivechemical preparation.

y

Reserve : Printing of a material which inhibitsthe dye take up, and then over dyeing the fabric.


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Transfer printingy In transfer printing, a design

printed on paper by using paperprinting techniques, are transferredon to a textile material by Heat (Thermal Tranfers) or by W ater ( W ettransfer ) or by a vacuum (Vacuume Transfer)


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Thermal Transfersy M elt transfersy

Adhesive transfersy Sublimation Transfers.


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FINISHING -D RYINGy Drying operation is carried out by y 1. Stentering and drying machiney 2. Cylinder drying Machiney 3 IR or RF dryers.y

y The process also associated with shrinkage of thefabric and bringing in Dimensional Stability


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STENTER


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SOFT FINISHy Fabric surface can be made to give a soft touch by a

physical process , named CALENDERIN G and it isonly a temporary finish.

y There are also special effects like embossedCalendering, done with chemicals and they are morepermanent


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Three B owl Calendering


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V iew of a Calendered Cloth


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Finishing operationsy Finishing operations change the properties of the fabric or

yarn. They can increase the softness, luster, and durability of textiles.

y Finishing can also improve the water & Soil or OILrepelling and flame resistant properties of the fabric.

y The characteristics of textiles can be altered by physicaltechniques (dry finishing processes) or by application of chemicals (wet finishing processes).

y Luster can be added by both physical and chemicalmethods.

y Characteristics like flame or water repellency can only beobtained by wet finishing


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PRE-SHRINKING ( Sanforizing)


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Sanforizing M achine


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CHEM ICAL FINISHING Various performance characters could be imparted to

a fabric by applying functional chemicals at thestuttering machine, followed by drying and Curing orPolymerizing.

Various such applications will be discussed next


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FINISHES WITH CROSSLINKERSThe wrinkle free finish also known asy "Easy Care",y

Durable Press ",y " Wrinkle-Resistant ",y " Wash and Wear ",y "Non-Iron " is obtained by cross-linking cotton.y SCRUNCH or crushed look is also obtained by giving

the same finish while keeping the garment in acrushed state.


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Easy-care finishThe application of an easy-care finish,reduces thetendency of the fabric to crease in wear and makes itmuch easier to iron after laundering.The same finish also prevents shrinkage during washing.These types of finish have greatly reduced themaintenance which cotton in everyday use requires,

and have increased its suitability for apparel of alltypes.It is achieved by crossilnking reaction of cellulose withresins like DNDHEU or G yoxal.


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D efinition:W ATER /Oil Repemmalnt finishD efinition:W ATER /Oil Repemmalnt finish

Repellent finishing:

Wetting and soiling of a textile is avoided by repellingthe soiling substance, by a chemical coat applied to afabric surface.

This is achieved by application of Fluoro Carbon resins with an Isocyante back bone.


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Mode of action of fluorocarbons

Interaction withinthe liquid (e.g.

water, oil)>

Interaction between liquid surfacemolecules and the substrate

NO WETTINGOF THE SURFACE

Reduction of the surface tension of finished fabrics


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Water Oil

Water

Oil

Household washes

Dry cleaning

or

Ironing

Tumbling

or

Mode of action of fluorocarbons


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A NTI B A CTERIAL and A nti

mildew FINISHESy The material which should be worn for a longer period

like without washing Like army uniforms could betreated against mildew and bacterial attacky Woolen and silk material which are more prone to

insect attachs like white moth attacks, could be given a

insect repellant finis.


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New finishesy With the development of technology many more new

types of finishes are given today to increase the valueof a finished cloth. Some of the modern finishes areusing in the finish

y Wellness productsy Micro-granulated fragrances/ Anti bacterial productsy

Constant temperature products are also availabletoday.


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M icroencapsulated Substances in

Finishing.


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M icro Encapsulated Products


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NEW FINISHESy The texyile industry finds always new techniques to

meet the needs of the changing fashions in the world.y

Hence the textile processing technology would benever be conclusive. One has to update the knowledge,almost on daily basis.

y New fibers, new chemicals, new application

techniques are constantly enriching this industry.


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y Thank You !

Introduction to Textile Processing for Non Tech

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