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Scouring: Objectives, chemicals used and their functions, method of scouring in machines as kier, J box, HTHP steamers

PREPARATORY PROCESSES FOR COTTON

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SCOURING

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• FATTY ACIDS• FATTY ALCOHOLS• OLEIC ACIDS• INSOLUBLE IN

WATER

• PECTIC ACID• COOH GROUP

PRESENT• INSOLUBLE IN

WATER

• POTASSIUM CHLORIDE

• POTASSIUM CARBONATES

• CALCIUM SULPHATES

• NITROGENOUS COMPOUNDS

• COLOURING MATERIALS

• PRESENT IN PRIMARY WALL AND LUMEN

FAT & WAXES PECTINS

IMPURTIES

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SCOURING

SCOURING can be carried out as a separate step of the process OR in combination with other treatments (usually bleaching or desizing) on all kind of substrates (fiber, woven fibers, knitted fibers).

Cotton chemical structure

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The main processes occuring, during scouring are

saponifiable oils are converted Into soaps,

proteins are hydrolysed into soluble degradation products

simpler amino compounds are dissolved or hydrolysed to ammonia

pectose and pectin are changed into soluble salts of pectic or metapectic acid, mineral matter is dissolved,

unsa ponifiable oils and waxes are emulsified by the soluble soaps formed from the saponifiable oils

dust particles are removed and held in a stable suspension form in the kier liquor by the detergent present therein.

SCOURING

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TYPE OF SCOURING

SOLVENT SCOURING

AQUEOUS SCOURING

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AQUEOUS SCOURING

1. WATER2. CAUSTIC3. SEQUESTERING

AGENT4. WETTING AGENT OR

SURFACTANT

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SEQUESTERING AGENT

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CHEMICAL REACTIONS

REACTION WITH CAUSTIC SODA

R – COO – H + Na OH R – COO – Na + H2O FAT & OILS SOAP

REACTION WITH SODA ASH(SODIUM CARBONATE)

2R – COO – H + Na2 CO3 2R – COO – Na + H2O + CO2

FAT & OILS SOAP

soap of sodium dissolve easy in water

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NaOH : 10 - 40 ml/lNa2CO3 : 2 g/l

Wetting agent : 2 ml/l Time : 60 minute

Temperature : 95oCLiquor ratio : 1:30

RECIPESCOURING PROCESS

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TemperatureoC

60oC

30oC

SCOURING

Rinsed by Hot Water And chill water

scouring process of cotton with Na2CO3 and NaOH used exhaustion method

0 15 75 minute

Time(minute)

NaOHNa 2CO3

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PROCEDURE

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TYPE OF SCOURING MACHINE

1.Batch process2.Semi- continuous3.Continuous

WITHOUT PRESSURE WITH PRESSURE

OPEN TANK,JIGGER, HASPEL, CLAPEAU, J-BOX AND OF L-BOX

KIER M/C, CLOSED JIGGER

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Schema of machine haspel Description:1. Roller up 2. Guide Roller 3. Guide Roller 4. Vessel5. Water pipe6. Steam pipe

Process of scouring cotton with haspel machine

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SCOURING PROCESS WITH JIGGER MACHINE

OPEN JIGGER M/C

CLOSED JIGGER M/C

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One of the scouring recipe of drill fabric with jigger machine is :Caustic soda (38o Be) : 10 cc / litre Wetting agent : 4 g / litre M:L ratio : 1 : 5Temperature : 100oC Time : 8 - 10 Rotation

After scouring material is cleaned with chilled water, hot water, and rinsed with cool water, rinsing with the help of water emitting stream.

SCOURING RECIPE

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SCOURING PROCESS WITH J-BOX MACHINE

A typical recipe (% o.w.g.) for J‑box

scouring is as follows. :

Caustic soda : 4.0

Soda ash : 1.5

Sodium silicate : 1.5

Wetting agent : 0.5

Detergent : 0.5

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The procedure for treating the fabric by the J box system consists essentially of ‑saturating the incoming wet fabric with relatively concentrated solutions of caustic

soda. Two different principles are used in the design of J boxes, depending on the ‑method by which the cloth is pre heated before storage. ‑Some J boxes, such as the used in the DuPont and Farmer Norton plants, have ‑separate chamber where the temperature of the material is brought to about 800C

before it enters the J box which is insulated sufficiently to ensure that the cloth ‑maintains this temperature approximately during its entire passage through it. An

alternative machine used is the Becco type. In this type of a J box the heat is ‑ ‑supplied by steam jets situated inside the box at the point of entry.

dilute concentrationslonger times higher temperatures

IN KIER

higher concentrationsshorter reaction times lower temperatures

IN J- BOX

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scouring Machine with pressure

Kier boiling is made from cylinder tube of rustproof iron or steel

capacities of this Kier boiling is variety from ½ ton until 5 ton of material

existence of pressure seed husk and other impurities will be able to release.

caustic soda liquor 1 - 5% wetting agent – 0.2 – 0.5% Time - 6 -10 hour pressure 1 – 3 atm

KIER SCOURING

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Pile the cloth,

Dissolve the chemicals in a separate tank,

Take water in the kier,

Circulate water along with the chemicals,

Start heating,

Close the lid but keep the air vent valve open,

when the air is completely expelled out with steam, close the air vent valve and develop the pressure

Heat for 8-10 hours at 1.5 kg per sq cm i.e. 1300C.

STEPS FOR FILLING THE KIER

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Blow off the kier,

Throw away the liquor,

Take fresh water,

Circulate the water,

Throw away the water,

Again take water,

Circulate and throw away,

Open the kier, and

Wash the fabric.

STEPS FOR EMPTYING OUT THE KIER

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ADVANTAGES OF J- BOX SCOURING SYSTEM

Daily production per kier would be only about 19000 meters/kier/day, which is rather

low. The J-Box system, gives a daily production of at least 80,000 m./day/per J Box.

The J-Box plants are suitable for routine fabrics such as dhotis, sarees, sheetings, mulls,

voiles, etc. Along with the J Box plants, the supporting machines such as pre washing ‑and post washing units, saturators, etc. are also to be equally production oriented.‑

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SCOURING