Scouring of Synthetics

8/2/2019 Scouring of Synthetics

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SCOURING OF SYNTHETICS

PolyesterNylon

Acrylic

Polyester- Cotton Blend

Polyester- Wool Blend

Polyester- Viscose Blend


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What is Scouring and why is it done?

Scouring is a process in which the fabric istreated with a mild alkali at high

temperatures for one to two hours toremove the natural and added impuritieswhich increases the absorbency of the

fabric by 90%-95% to give good whiteness.


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Scouring of synthetics is relatively simple since thefibres contain fewer impurities, most of which have at

least some degree of water solubility, the mostimportant being sizes and lubricants.

The major sizes used are-

Polyvinyl Alcohol

Carboxymethylcellulose

Polyacrylic acid

All of the above sizes are completely orpartially water soluble.


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Scouring of Polyester

Liquor content-1-2 g/l detergent

Non-ionic surfactant (if needed)

2 g/l soda ash

Soil suspending agent like sodiumtripolyphosphate (in case of heavily soiled goods)

For light weight material in the rope form or unset

filament form, the temperature should be below60c

For other material, scouring may be done at boil for

20-30 minutes or 4 to 5 ends in a jigger.


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Scouring of Nylon

Synthetic non-ionic detergents are usedalong with mild alkali.

Soft water should be used to minimizeretention of heavy metals by carboxyl group

of nylons. For heat set fabric temperature range is

75-80C For unset fabric temperature is 95-100C.

Liquor content for batch and continuous

process are shown in the table:


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Scouring

chemicals

Batch

process

Continuous

process

Non-ionicdetergent(g/L) 2-3 2-3

Anionicdetergent(g/L) 1-2 1-2

Soda ash 1-3 -

Sodiumpyrophosphate(g/L)

- 3-6

Temperature 70C 90C

Time (min.) 20-30 10-20


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Scouring of Acrylics

Before scouring high bulk fibres on cones arerelaxed in saturated steam at about 100c for 20

mins.

Liquor content:

1-2 g/L non ionic detergent

1 g/L trisodium phosphate at boil for 30 mins.

1 mL/L solvent based detergent to remove oilsand greases

After scouring bath is cooled at 60c and rinsed to

remove detergents.


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Scouring of Polyester-Cotton Blend

In P/C blends mild conditions of alkalinity andtemperature are maintained to avoid deterimentaleffects on polyester.

Different liquor contents and conditons for differentmachines are:


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Equipment Liquor contents

and conditions

Jigger Caustic soda (3%) at70c or at 100c for 15

min

Jigger soda ash (5-10

g/L),detergent(2-5 g/L)at boil OR NaOH (2-5g/L), detergent(2-5g/L) at 75 c

Winch NaOH(1-2 g/L) orsodium carbonate(2-5g/L) at 75 c

Pad steam Soda ash (5-10 g/L)and detergent (2-5 g/L)


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Other scouring agents which can be used are:

Trisodium phosphateEmulsifiable scouring agents


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Scouring of Polyester-Wool Blend

Liquor content-

0.5-1% non-ionic alkyl phenol polyglycol ethertype detergent

0.2-0.4 g/l soda ash at pH 8 to 9

Synthetic detergent solution at pH 5 to 6 can

be used to minimize degradation.

Scouring is carried out in a Dolly washingmachine.

Wool rich fabrics are in rope form and polyesterrich fabrics are in open width form.

In both cases, the time for scouring is 20-30

minutes and the temperature is 40-50c.


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Dolly washing machine


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Scouring of Polyester- ViscoseBlend

Scouring process is almost same as thatof polyester.

Liquor content- 1-2 g/l detergent

Non-ionic surfactant (if needed)

2 g/l soda ash

Soil suspending agent like sodiumtripolyphosphate (in case of heavilysoiled goods)


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For light weight material in the rope formor unset filament form, the temperatureshould be below 50c

For other material, scouring may bedone at boil for 20-30 minutes or 5 to 6

ends in a jigger.


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Modern methods of scouring

Solar Oven

A simple "hot box" solar collector,was modified into a cylindrical circulartrough solar concentrator for ease offabric loading and uniform year-roundheating. Combined scouring and

bleaching of blends by a pad-batchmethod was done using sodiumchlorite.


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ADVANTAGES-

Renewable source of energy i.e. solarenergy is used. Hence eco- friendly.

Cost effective as renewable resource

is used and bleaching and scouring isdone together.

Efficiency as high as convention

methods.


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LIMITATIONS-

Can be used only in those locationswhere sunlight is present through outthe year.

Set up cost is high.


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Comparison between Cotton andSynthetic scouring

Liquor for scouring cotton has a slightlyhigher concentration of alkali than that usedfor synthetics.

Time for scouring is more in case of cotton(8-24 hours) as there are more impurities incotton than synthetics (10-90 minutes).

Scouring of cotton done at boiling

conditions where as that of synthetics donein hot conditions.

Scouring of Synthetics

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