Dyeing off 100% cotton fabric with sulpher dye.

 

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:>>>