Garment Wet Processing
Presented by
Aart Geurtsen
Wet processing
of
Cotton Fabric
Current estimate of world cotton production is about
25 millions tons per year
This means 112 millions bales of 480 lb/heac.
China is the largest producer in
the world.
Top 5 World Producers of Cotton
(Year 2011)
9000
33500
10000
China 33500
USA 27000
India 15674
Pakistan 10000
15674
27000
Brazil 9000
X 1000 X 480 lb. bales
Source: United States Department of Agriculture
* Bangladesh = 66
The properties of the cotton fiber varies from the
conditions and the area where cotton is produced.
Preparation of the Cotton fabric
• Scour
• Pre-Bleach
• Prepare for dyeing
Option 1
• The scouring removes all dirts & chemicals present on the fabric, which
could interfer with the pretreatment (cationisation) of the fabric.
• It helps to make the fabric more absorbant allowing, in the same time, a
better diffusion of the chemicals used to pretreat or cationise the fibre.
Scour
0.5% Triscour JET conc
1.0% Soda ash
2.0% Caustic Soda 50%
96°C for 30 minutes
Rinse et neutralize
Option 2
142,150
Helps remove the oxidized oils and the yellow pigment in the cotton .
This bleaching will help
to obtain pale shades and more brilliant colors.
Pre-Bleach
0.5%
0.1%
2%
4%
Triscour JET conc (wetting + detergent)
Tristabilizer Jet-5 ( H2O2 Stabilizer)
Caustic Soda 50% (NaOH)
Peroxide 50% (H2O2)
(Temperature of 96°C for approximately 30 minutes)
This operation of bleaching will be followed by a neutralization
with acetic acid, as well as the neutralization of peroxide by a
catalase enzyme, such as Triminox GH.
Note: For a white, we will add an optical brightener
Tricoblanc BA 80% liquid.
0.8% - 1.0 % owg.
Prepare for dyeing
Jersey or Fleece
Applying lubricant
After pre-bleach, the cotton will need an application of a
polyethylene emultion and/or fatty acid in order to facilitate
the operations of napping or cut and sew.
This operation is usually made by nip padder
with:
30 gr. liter of Tricosoft MSG
This softener-lubricant is very easy to remove with a light
Scouring, before carrying out the dyeing.
Dyeing process with pigments
•
•
•
•
Scouring
Cationic pretreatment
Dyeing
Softener application
First Step
prior to
Garment Dying
In some cases the presence of hand modifiers, could
make the fibre practically hydrophobic
Good scouring is a must
0.5 gr./l. Triscour JET conc
1.0 gr./l. Sodium Carbonate
2.0 gr./l. Caustic Soda (optional)
Run 60 °C for 30 min.
(Optional 96°C for 30 minutes)
Scouring Process
60°C
1% Triwhite JET 5
1% Soda ash
30°C
Dyeing
5`
10`
10`
5`
Ring dye process
Why fixing the dyes at the surface of the fiber?
All conventional methods of dyeing suggest to penetrate completely the fiber.
In the ring dye process, we apply the dyes right onto the surface of the fiber to allow
subsequent wash down.
The mechanical action in the machine will contribute to give an old or worn out effect
to the garment, which will appear to have been washed many times in a laundering
machine.
Effect of Abrasion
Fiber Cationic Pigment Effect of abrasion
Pigment Dyeing (Ionic Bond)
Pigments
Pigment
Cationic Agent
Cationic Agent
Cotton
Fiber
Cationisation agent of positive load adheres to the surface of
fibre in a first operation named “pretreat” and then the dye of
negative charge adheres to the surface of the cationic agent in
the second operation, the dyeing.
Cationic Pretreatment Process
Dosing Texafix BR
Acetic Acid
60°C
Triscour Jet conc.
Tricellulase BPN
30°C
Dyeing
2`
5`
20`
15`
5`
10`
5`
Pigment Dyeing Process
Sample check
Acetic Acid
option addition
Texalev JL
60°C
Pigment + Tri Binder AC-M-2240N
by dosing
1. Rinse 20 ° C
2. Rinse 40 ° C
30°C
2`
15`
10`
20`
20`
10`
5`
Pigments
•
•
•
•
vs
Pigments
Direct
Reactive
Sulphur
others types of dyeing
Ionic bonds
Forces of Van der Waalls
Covalent bonds
Fixed by insolubilisation
Direct Dyes
The direct dye being of negative charge just like cotton,
makes them repulse. It is necessary in the case of the direct
dyeings to use an ELECTROLYTE which will separate in
positive and negative ions in the bath from dyeing.
•The positive ions will move towards fibre to fill the negative charge of cotton.
•The negative ions will make competition with the dye of negative charge and
will make it to go up on fibre by force of repulsion.
Salt will help the dye to get on fibre, the
temperature will help with the swelling of fibre,
and a neutral or slightly alkaline pH to help with
the solubilizing groupings.
Classes of Direct Dyes
Class A: These dyes have a great capacity of migration even when electorlytes are
involved. It can be unequal at the beginning, but will level out when a
temperature of 205°F is reached
Class B: These dyes have less migration and use less électrolytes. The
levelness of these dyes can be controlled by by salt addition. It is very
important that the dye is also applied from the very start.
Class C: These dyes have a very poor capacity of migration and
they are very sensitive to the electrolytes. In certain cases these dyes exhaust
quickly without addition of salt.
Note: When temperature decreases the affinity of the dye for fibre also
decreases, but it increases its capacity of migration towards the other sites,
thus improving levelness.
Procedure for Direct Dyes
Dose Salt
Trilube XTC
96°C
Soda
Dyes
Tricofix NZ
Acide
50°C
30°C
Precautions in production
The dissolution of the direct dye is done at the temperature of the cycle of
dyeing, This means 96°C except for the black 22 were we add the dye to the
warm water already in agitation to avoid agglomeration of dye.
Dosing(proportioning) of the dye is done by the return water in the
addition tank .
Reactive Dyes
The dye is not attracted towards fibre, we have to use an
electrolyte to push the dye towards fibre
The reactive grouping of the dye bonds with the alcohols group of the
cellulose which is present as an atom and will form a very solid covalent bond.
The reaction between fibre and the dye will release acide HCl, This is why
it will be necessary to compensate with alkali to keep a pH of ±11. Deep
shade generate more HCL and consequently requires more alkali to obtain
our pH.
Refer to table of Alkali for good fixation
Reactivity of the dyes
Trichloro pyrimidine
Drimarene XZ
Monochloro trazine
Cibacron E, Procion H/HE, Triactive HE
Vinyl Sulphone Monochlorotrazine
Triactive DF
Vinyl Sulphone
Triactive & Remazol
Monofluoro triazine & Vinyl sulphone
Cibacron C
Dichloro quinoxaline
Levafix E
Monofluorotriazine
Cibacron F
Difluoro monochloro pyrimidine
Levafix E/A Drimarene K/R
Dichloro triazine
Procion MX
Low.
Reactivity
High
Precautions in production
The dissolution of the reactive dye is done at the temperature of the
cycle of dyeing, Exemple: 60°C for Triactive DF, or 80°C for Triactive
HE. Add the dye powder to water with agitation, to not create
agglomeration of dye
Dosing (proportional) of the dye and Alkali should be done with
fresh water and not by the return water in the addition tank
•
•
• Add the dye in 30 minutes or more,
allowing good diffusion in fibre before adding alkali.
Ensure to maintain a ph of ± 11 after the alkali addition to assure good
fixation of the dyes.
6
Options
Option 1. Triactive DF 60 C
Option 2. Triactive Hot type 80C
Run
for45 minutes
80C
10’
6
30min
Run
for45 minutes
60C
10’
1
2
3
4
45’
5
30 min
Tex Alkali ASL
Soaping
30°C
20’
Dyes
LegendAGD, 2. TriminoxProcess
1. Graph
Tridefoam
GH, 3. Salt,
Cycle
4. Trilube BW,
Products Addition
5. Triactive dyes
6. Dosing Tex Alkali ASL
Drop Bath
Soaping is performed at 96 C with Triquest HON for 10 minutes
Optional Step
Soaping of the Reactive dyes
In reactive dyeing, usually the dye will be fixed on fibre, but there will be
also hydrolized dyes on the surface of fibre.
Indeed certain bonds are done with fibre, but unfortunately some are also
done with water.
For this reason it will be necessary after fixing, to rinse fabric very well
and make a soaping with Triquest HON wich is a very good dispersing and
anti-redeposition agent.
In this way the remaining electrolyte will be removed, thus reducing the
affinity of the dye for fibre, thus helping the washing off. The dye not fixed
and hydrolized will be removed in its turn and we will obtain better rubbing
and washing fastness .
Stripping of the Reactive dyes
Option #1
4 gr./l. Caustic soda 50%
heat to 80°C
2 gr./l. Tritex TD (Thioreadioxide)
heat to 100°C
Run for 30 minutes
rimse and neutralize
Option #2
1 gr./l. Soda Ash pH 10 - 11
20 gr./l. Sodium Hypochlorite (NaOCl)
heat to 50°C
run for 20 minutes
Rinse
Neutralize with 2 gr./l. Sodium Métabisulphite
50°C for 15 minutes
Dyeing with Sulphur Dyes
(For Deep Black Shades)
These dyes are usually insoluble and require to be solubilized
or reduced to be able to penetrate fibre.
They will be finally rendered insoluble again to remain permanently.
Example formulation of the bath reductor for 18 % of dyeing
1.0gr./l.
1.0gr./l.
0.5gr./l.
30.0 gr./l.
12.0 gr./l.
11.0 gr./l.
18% owg
Tridefoam AGD
Triquest XRD
Technowet SW-1
Salt
Dextrose
Caustic Soda 50%
Tricosulphur Black RC liq.
Temperature 96° C for 30 minutes
Procedure for Sulphur Dyes
Procedure for Sulphur Dyes
Salt, Dextrose, Caustic
Tricosulphur Black RC liq.
SW-1
Trioxy AL
96°C
XRD
1°C min.
85°C
AGD
Soda
80°C
3°C min.
Overflow
rinse.
50°C
40°C
10’
20’
20’
10’ 30’
20’
Oxidation of suffur dyes
Oxydation of this dye is very important to obtain good fastness.
Alkaline Oxidation
1 gr./l. Soda ash
2%
Trioxy AL
50 °C for 20 minutes
Trioxy AL remains the best, since we stay in alkaline
medium. The danger in the dyeing with sulphurs would be to leave the
material in acid medium at the end of the cycle, which could lead to
tenderizing of fibre by sulphuric acid formation during the
warehousing time.
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