Polyester (PES) Discharge/Disperse Discharge through Alkali (Soda Ash, Na2CO3)

SUBJ-20:

Polyester (PES) Discharge/Disperse Discharge through Alkali (Soda Ash, Na2CO3)

Chemicals:

Synthetic Thickener (Polysacchride), Soda Ash, Sodium Hydro sulfite and Caustic for Reduction Cleaning (although not necessary, it is done to have shin and glorious effect), Disperse Dyes

1. Stable to Alkali

2. Not Stable to Alkali.

Bit Discussion:

Polyester dyed or printed fabric can also be discharged but discharging requires more severe conditions like chemicals and parameters to obtain good results. Discharge of Polyester is more crucial and every dye cannot be discharged.

Normally there are two ways to Discharge a polyester fabric printed through Disperse dyes. First, utilization of simple alkali like soda ash which provides alkaline medium required to carry out discharge and other is done through utilization of Ragolit C and Tin Chloride.

Here in this post we are going to utilize former method in which we will be discharging though alkali soda ash. There are two kind of disperse dyes. One, Which are not stable to Alkaline medium at all and Second, Those disperse dyes which can bit stand with alkaline medium. So, this is basic principle which we are going to utilize in our both discharges, white and color Discharge.

Process:

Dyeing Recipe:

Padding Liquor{Continuous Process}

Disperse Dye (Not stable to Alkali)    30  g/Kg

Acetic Acid                              To Adjust Ph between 5-6

Water                                                     Balance

Total                                                      1     Kg

Pad at pressure 2bar with pick up 70 to 80.

Dry at 110C° for 1Min.

After Dyeing, Not fixed Yet and remember, we need not to fix it here.

Print(Discharge):

White Discharge Recipe:

Synthetic Thickener(8%)                    Balance

Soda Ash                                             30  g/Kg

Total                                                      1     Kg

Color  Discharge Recipe:

Synthetic Thickener(8%)                    Balance

Disperse Dye (Stable to Alkali)          30  g/Kg

Soda Ash                                             30  g/Kg

Total                                                      1     Kg

Fixation:

Different fixation modes are tried like

1. Saturated Steam 102C° for 30min.
2. Curing(Dry Air) at 210C° for 1Min.
3. High temperature Steaming (170C°, 40% Moisture for 15Min)
4. Pressure Steaming (2.5Bar, 140C° for 30Min) {Recommended}

Only Fixation modes recommended for Discharge either white or Color is Pressure Steaming the fourth one. Other methods will not work as for as Discharge is concerned, Although color fixation is normally done through second and third option too. First one is big and all time failure for disperse dyes fixation.

Look here the difference of fixation Modes on end result.

Fixation through Curing 210C° for 1Min

White Discharge.......Color Discharge.

White Discharge.......Color Discharge.

 Fixation through Pressure Steaming 2.5Bar for 30Min.

Washing{Reduction Cleaning}:

§     Cold rinse

§     Hot rinse with Soap for 1Min.

§     Reduction Cleaning with

2g/L Soap

2g/L Caustic 48Be°

4g/L Sodium Hydro Sulfite {Na2S2O4}

§     Hot rinse with Soap for 1Min.

§     Cold Rinse

What if one has Disprese dyed piece{Fabric}, Which have been fixed too {Mean fixation has been carried out} :

Fixed dye will not be discharged through simple alkali technique as dye has completely make its space into the fabric and will be needed Rangolit C or Tin chloride to carry out the Discharge.

Remarks:

Hopefully, You will like this post and will be helpful for some of you geniuses around.

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