Scouring of Synthetics
Transcript of 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.