15 Nonwoven Fabrics

8/8/2019 15 Nonwoven Fabrics

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Nonwoven Fabrics.:. N onwovens are produced d irectly from fib res w ithoutthe need of m aking a yarn

.:. N onwoven fabrics can be produced at a very rap id rateo f p ro du ctio n

.:. B ecause o f a short and sim ple process and a h igh rateof production , nonw ovens can be produced veryeconomical ly

.:. F ib res w hich can not be used fo r a yarn can be utilizedto m ake nonwoven fabrics .

:. Layered com posite fabrics can alobe form ed


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Forrnatlon of N onwoven Fabrics.:. 'To create a nonwoven fabric:

.:. First a web is made either from staple fibres orcontinuous filaments

.:. Then the web is strengthened by using one of thefour following techniques:

(1 ) Adhesive Bonding(2) Mechanical Bonding(3) 'Thermal Bonding(4) Stitch Bonding


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Classlf lcatlon o f Nonwoven F a b r i c s

II

According to Web Formation

Wet Laid

D ry Laid

Melt Blown

1-

According to Bonding TechniqueI

Adhes ive Bonded

- Mechanical Bonded

The rma l Bonded

- Stitch Bonded


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Web Forrnatlon --Wet l.a ld.:. 'T he w et la id techno logy of m ak ing non-w oven fabrics

is based on paper m ak ing.:. In th is m ethod , the fib res are suspended in w ater to

create a slu r ry .:. 'T he suspension is then filtered on a screen to fo rm a

m at or w eb on the screen.:. 'T he w ater is then rem oved by suction or squeezing andthe m at o f fib res is dried.:. 'T he m at o f fib res is then com pacted and bondedtogether using d ifferen t bond ing techniques


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'Web Forma tlon ....Wet, L a i d

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a

Wet Laid w eb Form ing 'Technique


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Web Forrnatlon - Dry Laid.:. In the dry la id w eb form ing technique, the fib res areopened , b lended and cleaned and are then taken in to a

w eb form .:. 'T he m ach ine line used for dry laid w ebs are sim ilar toa typ ical short stap le spinn ing system and includes

series of open ing m ach ines and a carding m ach ine .

:. D epending upon the requ ired th ickness of thenonwoven fabric , a num ber of w ebs produced bycard ing m ach ine are la id on top of one ano ther and arebound together by som e m eans to fo rm a fabric


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Types of Dry . .Laid Web Forrnatlon.:. D epend ing upon the w ay the dry -la id w ebs are fo rm ed

and com bined together, the d ry-la id w eb form ingtech n lque is fu rther classified as:( 1 ) P a r a l l e l - L a l d(2 ) C ross-L aid(3) Air-Laid or R andom -L aid


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Type s of D ry-Laid Web Forrnatlon

+--- CardWeb

Carriage 4 I I I

Cross..La id Web Forrnatlon

FaR

A ir or R andom -Laid W eb Form atlon


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Web Forrnatlon --Melt, B lown.:. In th is m ethod the polym er is ex truded through thesp innere t and is then sprayed by m eans of hot gas o r

air on to a vacuum belt ..:. 'T he fibres are then bonded together to form a sheet o ffabric by m eans of therm al bond ing using calendar

rollers.:. 'T he fibres can a lso be deposited on a w eb form ed bydry-la id p rocess to form a com posite m ateria l.:. 'T h is m ethod can give a very fine nonwoven fab ric

su itab le for filtra tion and abso rben t pu rposes


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W eb Forrnatlon -Mel t , BlownP ia ,I ',m , er IG,a.

Imllll' ,compile-a.a'r

Pump' O ' . - . ~ . - - . ' ".. ..'1

I

Melt Blown Method o f W eb Format i on


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Bonding Techniques - A dhesive Bonding.:. In th is m ethod , th e tex tile m ateria l com posed of a w ebor ba tt o f fib res is bonded together by m eans of som ead he siv e m a te ria ls .

:A fte r app ly ing the adhesives to the w eb , it is necessaryto cu re the adhesives by hea ting or b low ing air,:A dhesive Bond ing is fu rther c lassified as:

(1 ) Sa tu ra tion B ond ing(2 ) Spray Bond ing(3) P rin t B ond ing


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(1 ) Saturation Bonding.:. In Satu ration bonding , the w eb of fib res is passedthrough a trough contain ing adhesive. 'T he excess ofad hesiv e so lu tio n i s squeezed ou t betw een ro llers n ip

.:. The saturation bonding can be applied In following twoways :

a 0

N ip Padding Lick. .up Padding


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(2 ) Sp ray Bonding.:. In sp ray bond ing , the adhesive is app lied to the w eb info rm of d rop le ts being sprayed from spray ing nozzles .:. 'T he adhesive is show ered on the sheet in a separa te

sp ray ing cham ber w ith the help of a ir.:. 'T he spary ing nozzles are rec ip rocated in the m ach ine

d irec tion to p reven t any streak ing on the fabric .:. Suction can also be app lied beneath the w eb to helpthe d rops of adhesive to penetra te the w eb sheet.


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(3) Print Bonding.:. In p rin tbond ing , ju st like regu lar co lou r p rin ting of

fabrics, the b ind ing agen t is applied in te rm itten tly overthe surface o f the w eb in fo rm of som e design .:. S ince p rin t bonding techn ique does not en tire ly coverthe surface o f the fabric , it leaves the fab ric so fter andm ore flex ib le as com pared to saturation or spraybonding

.:. 'T he adhesive or the b inder is applied to the w eb eitherfrom a ro tary screen or engraved prin t ro ll.

.:. C o lour b inders can also be used to p rin t designs alongw ith the b ind ing of the fib res


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(3) Print Bonding

E ng raved Roll P ri n t Bondi ng

)'~',~ ' ~ / "'/~io'aI, -aeen _,"' I I . . . . . . . . . . . . ~

~ . I" I ,

I I'

Rotary Screen P rint Bonding

;,


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Bonding Techniques - Mechanica l Bonding.:. In m echan ical bonding , the w eb of fib res isbou ndw itheach o ther by their en tang lem ent using m echanicaltech n lqu es.

.:. M echan ical bonded fabrics are usually g iven anadditional therm al bond ing treatm ent.

.:. 'Tw o m ain types of m echan ica l bond ing techniques are :(1) Pressure Felting(2) N eed le Felting


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( 1) Pressed Felts.:. Fabric sim ply known as felt has been produced about4000 years ago by the Chinese by the process of

pressu re feltin g..:. In th is m ethod , conven tionally w ool fibres are used

which are sub jec ted to m oistu re heat and m echan icalpressure, Th is causes the fib res to get en tang led w itheach and the lndiv idual fibres can no t slip back form inga fabric .

:M anm ade fibres can no t be used to fo rm pressed felts,how ever a b lend of w ool and m anm ade fib res can beused to create such a fabric .


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(2) Needle Felts.:. F ib res o ther than wool can be converted in to a feltedfabric by m echanical en tang lem ent of the fib res using

barbed need les. Such a fab ric is called as needle felt.:A series of need les are m oun ted on aboard or fram e

called as need le board.:. 'T he needles are d riven dow n in to the w eb of fib res and

are w ithdraw n. In th is w ay each barbed needle punchesthe fib re w eb entangling them together to form aneed le felt fabric .


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(2) Needle F elts

A Barbed N eedle

()oI/'I" ~"_" "L~"_~"~" __"_ "_~ L_

ANeed l e Loom


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Bonding Techniques - Therm a l Bonding.:. In therm al bond ing , a w eb of fib res is c rea ted by

m ix ing it w ith a m eltab le m ateria l. Therm al bond ing isachieved by heating the fib re w eb un til the m ateria lm elts down and becom es adhesive and then the w eb iscoo led down to hold the fib res together .

:. For bond ing m ateria l e ither adhesive is m ixed w ith thefib re w eb in the fo rm of pow der or therm oplastictex tile fib res can also be used .

:. D uring therm al bonding / pressu re can a lso be app lied .:. For hea ting the fib re w eb , various techniques can be

used as shown below :


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Bonding Techniques - Therm a l Bonding(j. .

Calendar T herm al Bondi ng Conveyor O ven Therm al Bonding

'D rum O ven Therm al Bonding


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Bonding Techniques - Therma l Bonding

01,OJ,'It ip l:e ' IO IJ 'ener C : I ~ ; l d , e ' C:ar1d(IJIIU~ ilie ' "e,edl

Powde r T he rma l Bonding


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Bonding Techniques - S titch Bonding.:. In stitch bond ing , the w eb of flb res i s held toge the r as

a fabric by means of stitched loops.:. S titches th rough the fib re w eb a re fo rm ed using row o f

need les and th ep rocess resem b les to w arp kn itting

K ln oc k iO ' i8 r'fable,\

S titc h B o n din g using L atch N eed le M icroscope Im age o f s titc h b o nd ed fabric


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U ses of N onw ovensDisposable Durable

WipesPampers

Surgical GownsSterilization Packs

MedicalWork Wear

Floor CoveringIndustrial & . Technical

FurnitureApparel

Civil EngineeringAutomotive


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Tufted Fabrics.:. 'T ufted fabrics are m ade by the com bination of :-( 1 ) Fou ndation C lo th(2 ) 'T ufts

.:. T he foundation clo th is norm ally a w oven fabricgenerally a p lain w eave or any open structu re m ade upof co tton/w ool or ju te can be used as a foundation .

:. O n the foundation clo th / tu fts are inserted .:. Tufts o f the fib res are inserted in to the open spaces of

the foundation clo th . For tu ft fo rm ation a special tu ft-form ing m achine can be used or tufts can be m ade byhand.


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Tufted Fabrics:A bunch o f fib res tied together by m eans o f a th readcan be used as a tu ft. Som etim es in stead of fib res,th reads can also be used as tu fts .:. T he tu fts are inserted in to the foundation clo thaccord ing to the requ ired pattern . V arious co lou redtu fts can also ,be used to p roduce co lou red designs .:. O nce the tu fts are inserted in to the foundation , theyare m ade perm anen t by using a natu ra l la tex coating o rby som e chem ical b ind ing agen ts. Som etim es instead o fusing la tex o r b ind ing agen ts, tu fts are sew ed to thefou ndation clo th .


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Characterls tlcs of Tufted Fabrics.:. Tufted fabrics are soft w ith low tensile streng th .:. P roduction of tufted fabrics take m ore tim e ascom pared to woven fabrics, because first w oven fabricis m ade and then tufts are inserted .

:. They are bulky in nature .:. O nly lim ited designs can be m ade on tu fted fabrics .:. Their dyeing and prin ting is very d ifficu lt. G enerallytu fts are first dyed and then inserted in to thefou ndation clo th to give co lou red effec ts .

:. Tufts once rem oved from the fabric are hard to repair.


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U ses of Tufted Fabrics.:. T hey are m ostly used as carpets, rugs, m ats, e tc .:. 'T hey are also used in bed covers and tab le c lo ths .

:. D ecorative fab rics are also m ade ou t of them .:. 'T u fted fab rics are also used as a fu rn ish ing m ateria l

.:. D resses are rarely m ade ou t of them .


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Laced Fabrics:A lace is an openwork fab ric m ade from in term eshingthreads in to a fab ric . In term eshing of th reads can becarried out by the fo llow ing m ethods :-( 1 ) U sing knitting needles (N eedle Po in t)(2) U sing bobb ins (p illow )(,3) U sing shuttles (T atting)(4 ) U sing crochet need les (C ro tchet)


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Laced Fabrics.:. L aced fabrics cou ld on ly be produced by hands till theinvention of the first au tom atic lace m ach ine in early1800s .:. 'T he laced fabric produced by hands is called as the

IIReal l.ace" .:. R eal laces take p len ty of tim e and their cost is h igh .:. B u t various patterns of laces can be produced on them odern lace loom s at huge quantltles and at a very lowcost.


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Characterls tlcs of laced Fabrics.:. S ince it is an open 'w ork fabric , it g ives a very low cover .:. Its p roperties are very sim ilar to kn itted fab rics .:. T heir dyeing is possib le bu t p rin ting canno t be done .:. 'T hey have h igh elastic ity so they can be stre tchedw ithou t dam ag ing the fabric .


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Uses of Laced Fabrics.:. L aced fabrics are used as shaw ls and scarves .:. L aces are stitched on the w oven fabrics to g ive variousd esign s .:. F ine laces are used as curtains .:. D ifferen t decora tive tex tiles are m ade from them .:. F ish ing nets are a lso m ade from laced fabrics.


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Bra ided Fabrics.:. B ra ided fabrics are produced by a special m ethod ofin terlacem ent known as braid ing or p laiting .

:. In bra id ing or p laiting , th ree or m ore yarns over andunder one ano ther are in terw oven to fo rm a flat ortubular c lo th known as a braided fabric .:. In bra id ing , instead of threads, cut strips of clo ths orstraw s can also be used for braid ing . 'The bra ided fabricshave rela tive ly narrow w id th as com pared to the w ovenfab rics .

:. 'T he process of bra id ing or pla iting is very m uch sim ilarto the process of w eav ing . Follow ing are the d ifferencesin braid ing and w eav ing


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Bra ided Fabrics.:. Inw eaving only two threads are used l.e. w arp andweft, but in braid ing three or more than three threadsare used .

:. ln weavlng threads alw ays interlace at right angles/whilein braid ing threads can in terlace at any angle .

:. Inw eaving only threads can be used,while in braid ingapart from threads straw s, strips of threads, etc can beused to produce a fabric .


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Characterlstlcs of B raided Fabrics.:. S tructure o f braided fab rics is very m uch sim ilar tow oven fab rics .:. T hey give good covering effect .:. B raided fabrics have a narrow w idth .:. 'T hey can be dyed and prin ted easily .:. 'T hey can be produced cheaply and on large scale .


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Uses of Braided Fabrics.:. 'T he are used as belts, cords, shoe laces, e tc .:. D iffe ren t k inds o f ribbons are also m ade from bra idedfa bric s .:. P lastic o r straw braids can be sew n toge ther to fo rm

hats .:. B raided fab rics can also be sew n together to form

braided rugs .:. 'T rimm ing and tapes for d resses can be m ade from

them .:. 'T ubu lar b raided fabrics are used as hose p ipes, ropes"

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15 Nonwoven Fabrics