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DIFFERENT CHEMICAL
PROCESSES
Kapil
Dyeing
Finishing
Namit
Pretreatment
Printing
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DYEINGy Dyeing is the process of imparting colours to a textile material in fibre,
yarn, cloth or garment form by treatment with a dye.
y Adye can generally be described as a colored substance that has anaffinity towards the substrate to which it is being applied. It is appliedto different substrate by using a different kind of machines.
y Different types of machines:- Pad Mangles
High Speed Beam Dyeing Machine
Jet Dyeing Machine
Jigger Dyeing Machine
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PAD-MANGLEy Introduction:- In this machine, DIP-NIP method is followed. The
main purpose of the mangle is to impregnate the material evenly with
dye liquor.
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FACTORS NEEDS TO BE
CONTROLLED:-S. No. Factors Guidelines Controlled by/
Observed by
1. Hardening of rubber
of bowls
75-85 Shore
Durometer
Hardness Meter
2. Time available forsaturation withliquor
Sufficient forthorough saturation
Speed
3. Methods of feedingthe fabric to the nip
Perpendicular to thenip
Threading arrangement
4. Tension on the fabric Just sufficient toensure smooth entry
Threading arrangement
5. Pressure on themangle rolls
Equal on both sides &sufficient for reqd.pick-up
Pressure gauges
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DRYING EQUIPMENTS:-y Many a sequence in cloth dyeing requires intermediate drying, i.e.
drying after padding but before fixation. Three types of machines areused for this purpose:-
Cylinder drying range
Hot flue Float dryer
PRECAUTIONS FOR GOOD RESULTS:- Use multi cylinder drying range and keep low steam pressure in first to
avoid shock drying.
In hot flue and float dryer use low speed fans in first chamber.
Add a suitable migration inhibitor to the padding solution(say, 1 g/l forthick cloth to 0.5 g/l for thin cloth).
Keep the wet pick-up at the mangle as low as possible.
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TO CHECK MIGRATION INDEX:-
y Take two pieces of cloth,(stitch one side),pad through thesolution, dry, develop. Compare these visually or measurethe reflectance of both the sides of these pieces. The
migration index is calculated as follow:-
M = 2k/(k+k)
Where, M= Migration index
k= k/s value of outside surfacek= k/s value of inside surface
In this test M=1 indicates no migration and M=2 indicates
complete migration.
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MIGRATION BECOME LARGE IF:-
y Pick-up is high
y Thickness of material is more
y Drying rate is high
y Polyester content in the blend is high
y Cloth is densely woven
y Proportion of finer particles in the pad-liquor is high.
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STEAMING/THERMOSOLING:-
y Some dyes can be fixed by steaming or thermosolingoperation.
Parameters Involved In Steaming:-y Temperaturey Speed
y Absence of air(for vat dyes)
Parameters Involved In THERMOSOL
ING:- Even distribution of temperature is necessary. Regular cleaning of the filters & airflow passage is
necessary to prevent blockage.
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AFTERTREATMENT:-y It involves Oxidation(for vat dye), Soaping & Final
rinsing.
Parameters To Be Controlled:- Conc. OfChemicals.
TemperatureAccording To Dye.
Time Of Treatment.
Flow Of Water In Rinsing & Efficiency Of Rinsing.
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HIGH TEMPERATURE BEAM DYEING
MACHINE:-y Polyester component of polyester containing fabrics is dyed
with High Temp. Beam Dyeing or Jet dyeing machine.
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CONDITIONS:- Fabric should be Properly heat set.
The selvedge should be plain & should not be dented orfolded.
Fabric tension must remain constant. There should be sufficient layers of cotton cloth wound on
the perforated beam before winding batch. This will avoidpossibility of perforation marks.
Batch size should be acc. To the cover factor, 20 cm foropen weave & 10 cm for closed weave fabric.
Liquor flow should be in one direction say inside-out.
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PRECAUTIONS:-
S. No. Parameters Precautions
1. Beam batching Ensure wrapping with filter fabricCloth should cover perforation length equally onboth sidesWinding under satisfactory tension
2. Rate of circulation Ensure good working of injector & main pumpDo not allow foam formation
3. Preparation of dyeliquor & additionto dye bath
Check for clear solution Or good dispersion bychromatography
4. Rate of heating Use automatic control, periodically checking
5. Pressure Record pressure periodically
6. Conditions of dyebath during dyeing
Notice deviation(check pH)
7. After treatment Follow suitable sequence
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JET DYEING MACHINE:-y In this machine, we can perform pretreatment and dyeing
of any fabric.
y It can perform high temperature dyeing(at 125c) at MLR of12:1.
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FACTORS NEED TO BE CONTROLED:-y Batch size
y Jet type
y Cloth speed
y Jet pressurey Liquor circulation
y Rate of heating/cooling
y Concentration Of auxiliaries
y Choice of compatible dye
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METHOD FOR CHECKING
OPTIMISATION OF COLOUR FEEDING:-
y Load machine with water and full fabric length.
y Prepare dye stock and auxiliary solution.
y Heat water in dye vessel and dye stock to 60c.
y Feed the stock solution to the dye vessel.y Continue to run the machine after adding dye stock for 2
min.
y Now stop the machine.
y
Open it and take out the fabric and cut about 1 meter ofit.
y Give one stroke to it, hang it warp way and allow it to dryat room temperature.
y Inspect the fabric for dye distribution.
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JIGGER DYEING MACHINE:-y This machine is used for dyeing woven fabrics.
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PRECAUTIONS:-
S. NO. PARAMETERS PRECAUTIONS
1. Batch size Weigh or measure the length accurately
2. Loading of jiggerStitch the fabric carefullyAvoid crease formation during loading
3. Colours/chemicals Weigh or measure accurately
4.Preparation ofDye-bath Dissolve the dyestuff as per standard procedure
5. Liquor ratio Maintain the MLR
6. TemperatureAutomatic temperature control is essentialOr Provide thermometer for manual control
7. After treatmentFollow suitable sequenceControl time, temp & pH
8. Drying Dry as soon as possible
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FINISHINGy Any operation for improving the appearance and
usefulness of a fabric after it leaves the loom or
knitting machine.
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FINISHING ON STENTER/FELT CALENDER
(CELLULOSE & PC BLEND FABRICS):-S. No. ITEMS PARAMETERS
TO CHECK
METHODSOF
CHECKING
STANDARDS ACTIONNECESSARY
1. Finish pastepreparation
Weighing Ofauxiliaries
Cooking time
Visual
Clock
At least one
hour
-----
2. Storage of paste
TemperatureViscosity
ThermometerStarchrefractometer
>80c Adjust thesteam flow
3. Applicationof finishingpaste
Moisturecontent offabric beforefinishingViscosity offinishing pastein pad-mangles
Feel orlaboratory test
Measurementof time reqd.for flow ofpaste throughATIRA
viscosity cup
About 6%
10%
around thestandard
To look intopreviousdryingprocessAdjust thetemperatureAdjust thesqueeze
pressure
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S. No. ITEMS PARAMETERS
TO CONTROL
METHODS OF
CHECKING
STANDARDS ACTION
NECESSARY
TemperaturePressure atpad-mangles
Wet pick-up
Thermometer
Pressure gauge
Weigh thefabric, dip inwater & passthroughmangle, weighagain andcalculateNoteconsumptionagainst lengthfinished
>85c
As per
standard
65 to 75% or
as per
standard for
the lot
Adjust thesteam flowAnalyserecord
Adjustpressure onsqueeze rolls
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S. No. ITEMS PARMETERS
TO CHECK
METHODS
OF
CHECKING
STANDARDS ACTION
NECESSARY
Moisturecontent of driedfabric
Moisturemeter orlaboratorytest
Around 6% Note steampressure &temp. in diff.chambersAdjust speedof steam flow
4. Expanders Before paddingmangles orbefore
stenter/feltcalendar
Visual No creaseformation
Adjustment ofexpanders orfabric
5. Fabricwidth
Delivery end ofthe machine
Measurementby tape
As fixed bythe mill
Adjust thewidth offabric onstretching
device
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ANTICREASE FINISHING:-S. No. ITEMS PARAMETERS
TO CHECK
METHODSOF
CHECKING
STANDARDS ACTIONNECESSARY
1. pH of clothforfinishing
-----Universalindicator
Neutral orslightly acidic -----
2. Finishing
pastepreparation
Mode of
addition ofchemicalsFinal volume
pH
-----
Measureheight ofsolutionpH paper or
meter
Add thermo-
setting resin& catalyst last
-----
-----
3. Applicationof resinfinishingsolution
Moisturecontent of f/cbefore finishingWet pick-upMangle
pressure
Feel orlaboratory test
Pressure
gauge
----- -----
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S. No. ITEMS PARAMETERS
TO CHECK
METHODS TOCHECK
STANDARD ACTIONNECESSARY
4.C
uring Temperature
Time
ThermometerThermo paper
Stop watchSpeedindicator
A
s fixed bythe mill 5%
As decidedby the mill
A
djust theworking ofheatersAdjust thespeed of themachine
The fabric is padded through the resin finishing solution, dried on the stenterand cured in the polymeriser.
The efficiency of curing can be checked as follow:-
Efficiency(%)= Nitrogen content in sample ANitrogen content in sample B
Sample A:- Sample of fabric after padding and drying.
Sample B:- Sample of fabric after padding ,drying ,curing and washing.
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CARBONISATION:-y This process involves the treatment of PC blend fabric with
70% sulphuric acid at room temperature. After treatmentfabric was rinsed with water, neutralised with soda ash andthen washed with water.
y Important process control during carbonization:-Quality of the acid:- Sulphuric acid should be checked for
presence of oxidising impurities by titrating with standardalkali.
Conc. And Temperature of Sulphuric acid:- The loss infibre bundle strength is higher with increase inconcentration And temperature of sulphuric acid.
Atwaddle meter and thermometer should be provided tomeasure concentration And temperature.
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WEIGHT REDUCTION:-y This process involves the use ofCAUSTIC SODAon
polyester & polyester containing blends to impart specialaesthetic properties to the material. 10% loss in weight isallowed.
yThree variables to control:-Temperature:- Rate of weight reduction increases with
increase in temperature. So, temperature should becarefully controlled.
PercentCaustic Soda:- The recipe is based on volumebasis. Hence amount of chemicals and volume of bathmust be controlled accurately.
Time:- This parameter is biased on first two parametersand weight loss level desired.
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REFERENCE:-y Process and quality control in chemical processing of
textiles byATIRA.
y
Internet source.
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BY:-
KAPIL SINGLA