In this method, temperature is kept in between 105-140°C and pressure is kept from 0 to 170 kPa. This method is also known as pressure dyeing which is used for highly crystalline synthetic fibres and their blends. This technique causes the fibre to swell even more than which achieved at 100°C temperature. So that dye molecules penetrate the fibre polymer system. It eliminates the need of carriers.
Recipe:
- Dye : 3%
- Dispersing agent : 1gm/lit
- Acetic acid : 1gm/lit
- Time : 60 min
- Temperature : 130°C
- pH : 4-5.5
- M:L : 1:10
Ø At first a paste of dye and dispersing agent is prepared and water is added to it.
Ø PH is controlled by adding acetic acid.
Ø This condition is kept for 15 minutes at temperature 60°C.
Ø Then the dye bath temperature is raised to 130°C and this temperature is maintained for 1 hour. Within this time, dye is diffused in dye bath, adsorbed by the fibre and thus required shade is obtained.
Ø The dye bath is cooled as early as possible after dyeing at 60°C.
Ø The fabric is hot rinsed and reduction cleaning is done if required.
Ø Then the fabric is finally rinsed and dried.
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