24840511 Cotton Process

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Yar n Dy ing Tips a nd T

niqu sF a b r i Dy ing T

niqu s a nd TipsT xtil p r o ssing p r obl ms &

olutions

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Machinery Articles FAQ

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Water Hardness - how it affects textileprocessing?

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Home >> Textile Dyeing-1 In t following t a bl you a n s ow t p re s e n e of W a ter Har dn e ss a ff ec ts t e var ious w e t p r oce ssing s

r ig t f r om d e sizing to finis ing.

Process Problem

De sizing

c ou r ing

Bleach ing

Mercer izing

Deac tiva te e nzym e s a nd m a ke s it in-solubl e som e siz e m a ter ia lslike st arch a nd PVA.

Combin e with so a p, p rec ipita te m e ta l-or ga nic ac ids. P r odu ce ye llowing of off-w h ite sha de s, re du ce c lea ning e ffic ie nc y a ndwa ter a bso r ption.

Dec ompos e bleach ba th s.

Fo r m insolubl e m e ta l oxid e s, re du ce a bso r be nc y a nd lust er Combin e with dy e s cha nging t he ir s ha de s, in-soubis e dy e s, ca us e tippy dy e ing, re du ce dy e diffusion a nd he nce re sults in poo r wa sh ing a nd r ubbing f a stn e ss.


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Dye ing

Finis h ing

Dusting a nd w h ite pa tche s a pp ear if the har dn e ss is v er y h igh .

Fo r m insolubl e m e ta l oxid e s, re du ce a bso r be nc y a nd lust er .Combin e with dy e s cha nging t he ir s ha de s, m a ke the m in-solubl e ,ca us e tippy dy e ing, re du ce dye diffusion a nd he nce re sults in poo r washing a nd rubbing fastness.

Ba sic Re qui re m e nts fo r Hyd r og e n P er oxid e Bleach ing

Wa ter Har dn e ss - How do e s it a ff ec ts T e xtile P r oce ssing?

De ter min a tion of W a ter Har dn e ss - How to T e st d e ta ils?

Indust r ia l Wa ter ofte ning T rea tm e nt - A d e ta ile d Ion Ex cha ng e Me th od

A simpl e p re trea tm e nt of c otton - Us e ful tips a nd rec ipe s of P er oxid e Bleach ing

Bio-s c ou r ing, t ech niqu e , tips a nd b e ne fits

Ass e ssm e nt of Bl eache d Goods

Us e ful Links on W a ter

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Copy r igh t 2006 - 2008 t he sm ar ttime .c om All r igh ts re s er ve d. L a st Upd a te d on:03-12-2008


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Cotton - Scouring and Bleaching -Pretreatment

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Pretreatment - A simple way

The current problem that mostly worries the modern dyers could be short-listed as

1. Shade-matching in buyer defined illuminants.

2. Shade tolerance limits for shade passing.3. Strict limits of various Color-fastness properties.

4. Lowest Processing cost.5. Lowest load in effluent water

6. Meeting the various buyer-defined pre-requisites like Oko-Tex standards

The survival of the modern dyer would therefore lie in the ability to

1. Prepare Right Fabric for dyeing2. Select Right Dyes and Chemicals for various fastness requirements.

3. Maximize the Right First Time (RFT) dyeing both in lab and bulk dyeing.

e Garbage in, Garbage out, what we sow that we reap all these sayings would be proved true in the caseof quality pretreatment. It has been told that dyeing is the mirror image of preparatory treatment. Unless the

preparatory fabric is excellent, one cannot achieve proper dyeing and finishing.

Bleaching T echnique:

The main aim of preparatory process is,

1. To remove natural pectin, wax, protein, coloring matter and unwanted minerals from the fiber,2. To make the substrate uniformly absorbent throughout its length and breadth,

3. To make the substrate uniformly white for pure white finishes with optical brighteners or for subsequentdyeing, mercerizing etc.

The ideal process of combined Scouring and Bleaching for cotton knits and yarn should have the following


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c ont e nts.

S.No Material Details R ecipe

1

Non-Ioni c de ter ge nt wit h h igh c loud point, low

foa ming a nd good re we tting p r op er ty o r a nofo a ming Anioni c we tting a ge nt 0.5 to 0.75% (o.w.f.)

2 Anti- crea s e lub r ica ting- a ge nt 0.3 to 0.50% (o.w.f.)

3 od a As h 0.5 to 1.0% (o.w.f.)

4 Hyd r og e n P er oxid e (50%) 2.0 to 4.0gms/lit er 5 P er oxid e ta bilizer 0.5 to 1.0 gm/lit er

6 C a usti c od a fla ke s 0.7 to 1.0% (o.w.f.)

the wa ter har dn e ss is a bov e 100ppm, t he n a suit a ble s e qu e st er ing a ge nt s h ould a lso b e a dd e d to t he a brec ipe (0.5 to 1.0g/l).

Chec k the pH of t he bleach ba th . It s h ould b e 10.5~11.0

A t rea tme nt a t 85C is giv e n fo r 45~60 minut e s, follow e d by

1. Hot w a s h a t 80C fo r 15 minut e s2. T rea tme nt wit h 0.5% p er oxid e -killer a t the p re -d e fine d t e mp era tu re

3. Hot w a s h a t 80C fo r 15 minut e s4. N e ut ra lize with 2 gms/lit er Ace tic Ac id.


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S o, t h is is t he optimum p r oce ss re qui re me nt fo r good qu a lity f a b r ic /yar n.

Bleaching Machines :

Jigg er , win ch , soft-flow, ca bin e t a nd c ontinuous bl each ing ra ng e s su ch a s B e ning er are som e of t he r outimach ine s us e d fo r te xtile bleach ing.

me useful hints in Hydrogen Peroxide bleaching:

ma ximum bl each ing ac tivity f r om h yd r og e n p er oxid e is obt a ine d g e nera lly a t a bout pH 11.5. In p rac ticea linity le ve l is a ltere d to suit fib er s e nsitivity a nd bl each ing p r oce ss re qui re me nts; e .g. wool, c otton, a moud e tc . S e lec tion of t he a lka li to b e us e d in p er oxid e bleach ing is d e pe nd e nt t here fore on t he fiber s o r the

nd b e ing bl eache d. S odium Hyd r oxid e a nd S odium car bon a te will be us e d g e nera lly on ce llulos e fiber s, wmoni a a nd t e tra sodium py r op h osp ha te are us e d w he n bl each ing p r ote in fib er s.

Ba sic Re qui re me nts fo r Hyd r og e n P er oxid e Bleach ing



Indust r ia l Wa ter S ofte ning T rea tme nt - A d e ta ile d Ion Ex cha ng e Me th od

A simpl e p re trea tme nt of c otton - Us e ful tips a nd rec ipe s of P er oxid e Bleach ing







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Bio-scouring:

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Bio-s c ou r ing wit h pec tina s e s ( e nzym e ) ha ve s h own p r omis e in re plac ing t he dition a l a lka line s c ou r ing t rea tme nt. S om e a uxiliar ie s suppli er s ha ve intr odu ce d a ne nzym a tic p r oce ss to re mov e h yd r op h obi c a nd ot her non- ce llulosi c c ompon e nts f r om c otton. T he ne w bis c ou r ing p r oce ss op era te s a t mild pH c onditions ov er a b r oa d t e mp era tu re ra ng e a nd ca n b e a ppli e d usin

e quipm e nt su ch a s j e t m ach ine s.t is c la ime d t ha t, du e to a be tter bleacha bility of enzyme-scoured te xtile s, bl each ing ca n b e carr ie d out we du ce d a mounts of bl each ing che mica ls a nd a uxiliar ie s. Bio-s c ou r ing e nzym e s ac tu a lly ma ke the subst rre h yd r op h ilic (wh ich c ould e xpla in b e tter bleacha bility), but t he y are not a ble to d e st r oy w a x a nd s ee ds, w

are there fore re mov e d in t he subs e qu e nt bl each ing p r oce ss.Major Benefits achieved due to enzymatic scouring or bio-scouring:

re is no n ee d fo r the us e of ca usti c sod a in e nzym a tic s c ou r ing. S o t h is p r oce ss re du ce d pollution lo a ds,TDS , BOD a nd COD in t he e fflue nt.

Enzymatic

scouring

Enzymatic scouring + bleaching with

reduced concentration of hydrogenperoxide and alkali

Re du c tion in r insing w a ter c onsumption

20 % 50 %

Re du c tion in BOD-lo a d 20 % 40 %

Re du c tion in COD-lo a d 20 % 40 %T entative R ecipe for Bio-Scouring:

A typi ca l p r oce ss fo r a pa d-b a tch pr oce ss c ombining s c ou r ing a nd d e sizing in on e singl e st e p is a s followimp re gn a tion a t 60 C (pH 8 - 9.5) wit h :

y 2 - 3 ml/l w e tting a ge nty 2 - 5 ml/l e mulsifi er

y 5 - 10 ml/l e nzym a tic c ompoundy 4 - 6 ml/l a myla s e

y 2 - 3 g/l s a lt


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a llow to dw e ll we t fo r 3 - 12 h , d e pe nding on t he a mount a nd typ e of st arch

y h yd r o e xtrac tion a nd r insing.

Applicability he e nzym a tic s c ou r ing p r oce ss ca n b e a pplie d to ce llulosi c fibre s a nd t he ir ble nds (fo r bot h wov e n a nd kngoods) in c ontinuous a nd dis c ontinuous p r oce ss e s.

Whe n e nzym a tic de sizing is a ppli e d, it ca n b e c ombin e d wit h e nzym a tic s c ou r ing.The pr oce ss ca n b e a pplie d using j e t, ov er flow, win ch , p a d-b a tch , p a d-st ea m a nd p a d- r oll e quipm e nt.Compl e te re f ere nce Link: h ttp://www3.itv-d e nke ndo r f.de /itv2/downlo a ds/d0004918/WG3Bu c Mare k.pdf

R elated topics of your interest:




Indust r ia l Wa ter S ofte ning T rea tm e nt - A d e ta ile d Ion Ex cha ng e Me th od


Bio-s c ou r ing - t ech niqu e , tips a nd b e ne fits




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Assessment of Bleached goods

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Introduction: Absolute value for assessing bleached goods is difficult to define, since they are invariably

ciated with the subsequent use of the fiber, yarn or fabric.

factors which form the basis of any assessment include :

1.

Wh

ite

ne

ss 2. Che mica l o r ph ysi ca l da m a ge

3. Abso r be nc y, p ar tic ular ly of ce llulos e m a ter ia ls a nd bl e nds.

4. P re s e nce of re sidu a l non- ce llulos e m a tter .

5. Le ve lne ss of p re para tion.

6. F ree dom f r om impu r itie s, e .g., c otton s ee d

7. S

uita

bility for

subse

que

nt pr o

cess

es

e.g., spinning, dy

eing

etc.

la st t hree f ac to r s are subj ec tive to t he e xte nt t ha t the y are be st a ss e ss e d visu a lly o r judg e d by subs e qu e nt p r oce ssing on pl a

fir st fou r f ac to r s ca n b e m ea su re d qu a ntit a tive ly a nd t he ba sis fo r su ch a na lysis follows:

Assessment of Whiteness :


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Wh ite ne ss is g e nera lly a ss e ss e d inst r um e nt a lly a s p h ysica l m ea su re m e nts p r ovid e obj ec tive va lue s t ha t are ind e pe nd e nt of t hend c olo r s e nsitivity of t he e ye s. All inst r um e nta l m e th ods illumin a te the s a mpl e a nd t he m ea su re the a mount of lig h t re flec te d. us ha ve the a dd e d a dv a nt a ge tha t the illumin a nt a nd t he vie wing c onditions ca n b e c los e ly sp ec ifie d. T he a ss e ssm e nt ra ng e s

m ea su re m e nt of re flec ta nce a t a singl e wa ve le ngt h to a c ompl e te sp ec tra l s ca n w h ich ca n b e c omput er pr oce ss e d to giv e aff ere nce or Whiteness ../default . And er s a nd D a ul, on e of wh ich is rec omm e nd e d in t he AATCC t e st m e th od 110, ha ve re vi

the s e wh ite ne ss indi ce s.




Indust r ia l Wa ter S ofte ning T rea tm e nt - A d e ta ile d Ion Ex cha ng e Me th od








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24840511 Cotton Process

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