Experiment
name : Dyeing off 100% cotton fabric with sulpher
dye.
Theory: Sulpher dyes are complex
heterocyclic molecules or mixtures formed by melting or boiling organic
compounds containing amino or nitro groups with Na-polysulphide and
Sulpher. Sulpher dyes are so called as
they all contain Sulpher linkage within their molecules. Sulpher dyes are
highly coloured, water insoluble compounds and have to be converted in to water
soluble substantive forms (lucoforms) before application to the textile materials.
This conversion is carried out by a treatment with a reducing agent like dilute
aqueous Na2S. Since this lucoform of Sulpher dye is substantive to cellulosic
materials. They are absorbed on the fibre surface. Then they are reconverted
original water insoluble form of dye by oxidation. This oxidation is carried
out by “airing” (exposure to air) or by using an oxidizing agent like
Na-dichromate (Na2Cr2O7). The reducing
agents converts the “S” in dye in to –SH group and the Sulpher linkages. Then inside
the material the thiols containing –SH groups are oxidized & thus
reconverted to original form of dye.
Objective:
1.
To learn about dyeing process
of cotton fabric by sulpher dye.
2.
To dye cotton fabric by sulpher
dye.
Nature
of sample:
Pre-treated 100% cotton knit fabric.
Apparatus
required:
1.Beakers
2.Glass Rod.
3.Pipette.
4. Measuring Cylinder.
5. Digital Balance.
6. Tri-pod stand.
7. Gas Burner.
8. Thermometer.
9. Pot.
Process
sequence
- collection of pre-treated sample
- set water level
- add dye solution
- add Na2S solution
- add wetting agent solution
- add levelling agent solution
- add glauber salt salution
- add soda ash
- add fabric sample
- raise the temperature to 55deg C
- run time for 30 minute
- bath drop at 70deg C
- rinsing
- dry
Table1: Dyeing Recipe
|
SL
|
Process Parameter
|
Unit
|
Dossing
|
Stock soln:
|
|
01
|
Dyes
|
%
|
4
|
1%
|
|
02
|
Na2S
|
g/L
|
10
|
10%
|
|
03
|
Wetting Agent
|
g/L
|
1
|
1%
|
|
04
|
Glauber Salt
|
g/L
|
10
|
10%
|
|
05
|
Levelling Agent
|
g/L
|
1
|
1%
|
|
06
|
Soda Ash
|
g/L
|
5
|
3%
|
|
07
|
Sample Weight
|
gm
|
5
|
---
|
|
08
|
M:L
|
-----
|
1:30
|
---
|
|
09
|
Temperature
|
degC
|
95
|
----
|
|
10
|
Time
|
min
|
30
|
----
|
Calculation:
Total Liquor = Fabric weight X L [M:L = 01:30]
=
5 X 30
=
150mL
Dye = (Fabric weight X x%) / stock
solution%
=
(5X4%) / 1%
=20mL
Na2S =
= (Total liquor X 'x'g/L) / (stock solution% X 1000)
=
(150 X 10) / 10% X 1000
=
15ml
Wetting Agent = (Total liquor X 'x'g/L) /
(stock solution% X 1000)
=
(150 X 1) / 1% X 1000
=
15ml
Levelling Agent = (Total liquor X 'x'g/L) /
(stock solution% X 1000)
=
(150 X 1) / 1% X 1000
=
15ml
Glauber Salt = (Total liquor X 'x'g/L) /
(stock solution% X 1000)
=
(150 X 1) / 1% X 1000
=
15mL
Soda Ash = (Total liquor X 'x'g/L) / (stock
solution% X 1000)
=
(150 X 5) /3% X 1000
=
25ml
Initial Water = total liquor - (chemical 1
+ chemical 2 + chemical 3 ...)
=
150- (20+15+15+15+15+25) mL
=
150 -105 mL
=
45mL
Process Curve:
Sample attachment:
Comment:>>>>
Conclusion:>>>
