pretreatment of textile

50
TYPES OF SINGEING

description

singeing, desizing, bleaching & other textile processes

Transcript of pretreatment of textile

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TYPES OF SINGEING

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Plat singeing machine consist of one or two copper plate in form of curve.Heater of plat using charcoal or mixture between air and gas. Fabric overcome by friction at hot damper smolder with speed 125 – 250 metre/minute so that fur will burning.

Figure of plat singeing machine

Description of figure: 1. Guide rollers 2. Singeing plat 3. Fabric

PLAT SINGEING MACHINE

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CYLINDER CIRCULAR OF SINGEING MACHINE

Cylinder singeing machine is development of plate singeing machine,its

made cylinder of copper, hot from within using gas fuel, charcoal, oil,

electrics. Fabrics overcome at circular cylinder of giration by two surface,

like at burner of plate fur, burner of cylinder fur also yield lustrous fabric.

Both types of this machine very good to heavy cotton fabric type.

Description of figure : 1.Guide rollers 2. Fabric 3. cylinder

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DISADVANTAGES

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UNWINDING

PRE-BRUSHING SINGEING POST-BRUSHING IMPREGNATION BIG-BATCH

GAS SINGEING

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GAS SINGEING

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SINGEING

BEFORE AFTER

SINGEING SINGEING

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SINGEING

This is fabric

going through

a singeing

machine

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SINGEING SCOURING MERCERIZING BLEACHING DE-SIZING

DESIZING

Onto de-sizing…

PRE-TREATMENT

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The reason for de-sizing because during the spinning and weaving process, the fabric goes through sizing.

DESIZING

SIZING is when

SIZE is applied to

the fabric to protect

it from the abrasive

action of the loom.

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WHAT IS SIZE?

Natural sizing

agents are mostly

based on starch

and starch-

derivatives. There

are also synthetic

sizing agents such

as modified

polyesters

DESIZING

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DESIZING

De-sizing is the removal of sizing agents from the fabric using

enzymes, acid, oxidative agents, etc. Enzymatic de-sizing is the

most common.

STARCH (AMYLOSE)

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ROT STEEPING

ACID STEEPING

ENZYME DESIZING

TYPE OF DESIZING

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STARCH

Attack randomly and produce

Attack at particular places

and produce

dextrins

FAST REACTION

maltose

SLOW REACTION

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Amylase Optimum Optimum Effect of Effect of

PH Temp(°C) NaCl CaCl2

Pancreas 6.8-7.0 40-55 + +

Malt ∝ 4.6-5.2 55-65 — +

Malt β 4.6-6.2 40-50 — __

Bacterial 5.0-7.0 60-70 O +

ENZYME DESIZING

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Irrespective of what kind of de-sizing, the process includes:

Washing out the degradation products

Impregnation of fabric with

de-sizing agent

Allowing the de-sizing agent to

solubilize or degrade the size

DESIZING

Process route

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DESIZING

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OXIDATIVE DESIZING

(1) Sodium Hypochlorite 2 g/l at room temperature

(2) Hydrogen Peroxide 1 to 2 volume

Sodium Hydroxide 7 to 15 g/l

pH 10.0

Steamed for 2 to 3 minutes

Temperature 30° to 40° C

Pad cold and store overnight

The residual starch content on the weight of the fabric after desizing should be less than 1.0%

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DESIZING EFFECIENCY

CONVENTIONAL METHOD

TEGEWA RATING

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W1 W3

W2 W3

CONVENTIONAL METHOD

W1 WEIGHING

W2 DESIZING

W3.

TREATMENT WITH HCl

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TEGEWA METHOD

PREPARTION OF TEGEWA SOLUTION

Potassium iodide (10 gm. Of KI (100%) in 100 ml water

Add 0.6358 gm of iodine (100%) stir and shake

Fill up to 800 ml with water then complete to 1000 ml with ethanol

Shelf life approx 6 months only

METHOD & ASSESSMENT

Spot drop wise Tegewa solution onto fabric

Rub in gently and Assess change of colour

Grey fabric:

No change of colour = no starch size present.

Desized fabric:

Pale blue to bluish violet = refer to violet scale TEGEWA This indicates residual Starch content

Violet =of starch size with synthetic size

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FABRIC IN OPEN WIDTH

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CONTINUOUS DESIZING IN j- BOX

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CONTINUOUS PROCESS FABRIC FORM

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SINGEING SCOURING MERCERIZING BLEACHING DE-SIZING

SCOURING

Let’s talk about scouring………….

PRE-TREATMENT

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SCOURING

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• POTASSIUM CHLORIDE

• POTASSIUM CARBONATES

• CALCIUM SULPHATES

• NITROGENOUS COMPOUNDS

• COLOURING MATERIALS

• PRESENT IN PRIMARY WALL AND LUMEN

• PECTIC ACID

• COOH GROUP PRESENT

• INSOLUBLE IN WATER

• FATTY ACIDS

• FATTY ALCOHOLS

• OLEIC ACIDS

• INSOLUBLE IN WATER

FAT & WAXES

PECTINS

MINERALS

PROTEINS

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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SCOURING

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TYPE OF SCOURING

SOLVENT SCOURING

AQUEOUS SCOURING

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SOLVENT SCOURING

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SOLVENT SCOURING

DRY CLEANING

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SOLVENT SCOURING

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ADVANTAGES

dissolve

low liquid surface tensions penetrate

evaporate

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DISADVANTAGES

flammable explosion hazards

carcinogens

atmospheric ozone depletion

phosgene

and hydrochloric acids

corrosive to met

damage cellulosic fibers

expensive recovered

removal of motes, metal ions, starch and

other solvent

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SOLVENT SCOURING

COMMON SOLVENTS

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PROPERTIES OF SOLVENTS

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Boiling Point

Specific Heat:

Latent Heat of Evaporation:

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AQUEOUS SCOURING

1. WATER

2. CAUSTIC

3. SEQUESTERING

AGENT

4. WETTING AGENT OR

SURFACTANT

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SEQUESTERING AGENT

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CHEMICAL REACTIONS

REACTION WITH CAUSTIC SODA

FAT & OILS SOAP

REACTION WITH SODA ASH(SODIUM CARBONATE)

FAT & OILS SOAP

soap of

sodium

dissolve

easy in water

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RECIPE SCOURING PROCESS

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scouring process of cotton with Na2CO3 and NaOH used

exhaustion method

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Materials dried is later,then weigh and perceived, do test of fabric absorpsion

Afterwards cloth cleaned by hot water ,then cleaned to be chill water

Fabric done at solution process with temperature 95oC,then stir to flatten during 60 minute

Water and chemical agent prepared as according to liquor ratio at recipe

Weigh Materials and chemical agents as according to calculation of recipe

PROCEDURE