pretreatment of textile
Post on 07-Nov-2014
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TYPES OF SINGEING
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
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
DISADVANTAGES
UNWINDING
PRE-BRUSHING SINGEING POST-BRUSHING IMPREGNATION BIG-BATCH
GAS SINGEING
GAS SINGEING
SINGEING
BEFORE AFTER
SINGEING SINGEING
SINGEING
This is fabric
going through
a singeing
machine
SINGEING SCOURING MERCERIZING BLEACHING DE-SIZING
DESIZING
Onto de-sizing…
PRE-TREATMENT
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.
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
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)
ROT STEEPING
ACID STEEPING
ENZYME DESIZING
TYPE OF DESIZING
STARCH
Attack randomly and produce
Attack at particular places
and produce
dextrins
FAST REACTION
maltose
SLOW REACTION
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
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
DESIZING
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%
DESIZING EFFECIENCY
CONVENTIONAL METHOD
TEGEWA RATING
W1 W3
W2 W3
CONVENTIONAL METHOD
W1 WEIGHING
W2 DESIZING
W3.
TREATMENT WITH HCl
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
FABRIC IN OPEN WIDTH
CONTINUOUS DESIZING IN j- BOX
CONTINUOUS PROCESS FABRIC FORM
SINGEING SCOURING MERCERIZING BLEACHING DE-SIZING
SCOURING
Let’s talk about scouring………….
PRE-TREATMENT
SCOURING
• 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
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
SCOURING
TYPE OF SCOURING
SOLVENT SCOURING
AQUEOUS SCOURING
SOLVENT SCOURING
SOLVENT SCOURING
DRY CLEANING
SOLVENT SCOURING
ADVANTAGES
dissolve
low liquid surface tensions penetrate
evaporate
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
SOLVENT SCOURING
COMMON SOLVENTS
PROPERTIES OF SOLVENTS
Boiling Point
Specific Heat:
Latent Heat of Evaporation:
AQUEOUS SCOURING
1. WATER
2. CAUSTIC
3. SEQUESTERING
AGENT
4. WETTING AGENT OR
SURFACTANT
SEQUESTERING AGENT
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
RECIPE SCOURING PROCESS
scouring process of cotton with Na2CO3 and NaOH used
exhaustion method
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
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