Dyeing of 100% cotton Fabric with Sulphur dye by the discontinuous method.

Sulphur dyes are highly colored water-insoluble dyes. No direct affinity towards cellulosic fibers. These dyes have good & excellent light & wash fastness respectively. Sulphur dyes are the most commonly used dyes manufactured for cotton in terms of volume. Sulphur dyes are predominantly black, brown, and dark blue. Red sulphur dyes are unknown, although a pink or lighter scarlet color is available. These yes are water-insoluble compounds and have to be converted into water-soluble substantive forms  (known as leuco forms) before application to the textile material dyeing. For soluble dye into the water, a reducing agent is used(Na₂S).

Nature Of sample: 100% Cotton Woven Fabric (Pre-Treated).

Apparatus Required:  i) Beakers. ii) Glass Rod. iii) Pipette. iv) Measuring Cylinder. v) pH meter.        vi)Tripod Stand. vii) Gas Burner. viii)Thermometer. ix)Pot. x) Electronic Balance.

Process Sequence: 

Process Sequence:

Collection of 100% cotton Fabric (Pre-treated)

Reduction at 80°C for 10 minute

Dyeing with sulphur dye for 15 min at 100°C

Physical Oxidation

Cold  Rinsing 

Hot Wash 

Cold  Rinsing 

Drying

                           Recipe :

                                    Sample Weight: 10gm

                                    Sulphur Dye: 1% owf (S.solution-8% )
                                  
                                    Common Salt: 1 g/L (S.solution-1% )

                                    Wetting agent: .5 g/L (S.solution-1%)

                                    Sodium Sulfide :2 g/L (S.solution-2%)

                                     Caustic Soda : 2 g/L (S.solution-2%)

                                     Leveling agent: 1 g/l(S.solution-1%)

                                     Temperature for reduction: 80°C 

                                   Time for reduction: 10 min

                                  Temperature for dyeing: 100°C                                  

                                      pH: 13

                                      M:L: 1:40

    
Function Of chemical : 

Wetting agent:

To reduce the surface tension of water to allow it to spread drops onto a surface, increasing the spreading abilities of a liquid.

Sodium Sulfide: Used as a reducing agent

Caustic Soda:

Common Salt: Uses as electrolyte and Increases exhaustion rate. 

Leveling agent: To achieve uniform dyeing by controlling the rate of dyeing

   Calculation: 

                                  Sample weight: 10 gm

                                  Solution = (40 x 10) ml

                                                 =400 ml

                                  Sulphur dye = 10 x 8 %  / 1%

                                                        = 80 ml

                                  Caustic Soda = 400 x 2 x 100 / 2 x 1000

                                                     = 40 ml

                                  Leveling agent = 400 x 1 x 100 / 1 x 1000

                                                           = 40 ml 

                                   Sodium Sulfide = 400 x 2 x 100 / 2 x 1000

                                                     =40 ml

                                   Wetting agent = 400 x .5 x 100 / 1 x 1000

                                                          = 20 ml
                   
                                    Common Salt = 400 x 1 x 100 / 1 x 1000
                                                           = 40 ml 

                                    Initial water = 400 - (80+40+40+20+40+40) 

                                                          = 140 ml 

Process curve :

Fig: Process Curve

       Precaution:

1. We have to maintain laboratory precautions very carefully.
2. Every chemical we take should be taken accurately by pipette and should be taken very carefully.
3. We should be very careful during the time of working with a gar burner.
4. We should have to maintain the temperature accurately.    

  References: 

1. https://www.corrosionpedia.com
2. http://www.textiletoday.com.bd
3. https://www.google.com/search
4. https://en.wikipedia.org