1. The dyeing of polyester/cotton blend fabric with disperses and vat dyes.

Beam dyeing machine is used for dyeing polyester/cotton blends

First polyester fiber dyed with disperse dyes by HTHP method

Subsequently to this, Cellulose fiber is dyed with vat dyesOne bath dyeing methods

Steps :

1. Dyeing of polyester Take the predissolvesd disperse dye and vat dyes in the dye bath based shade percentage

First, polyester fibre is dyed with disperse dye using HTHP method and the same time vat dyes remains in dye bath because the vat dyes are not dissolved water so that it is could not move to cotton fibres Recipe

Disperse dye Vat dye Dispersing agent - 0.5-1%Wetting agent - 0.5-1%Temperature- 135CpH 4-52. Reduction Clearing and VattingThe dyed fabric treats with caustic soda (NaOH) and Hydrose (sodium hydrosulphite) at 60 C for 20 30 minutes.

Here two reactions is take place one is reduction clearing treatment and second one is vatting

i. Reduction clearing treatment:

To remove the unfixed dyes with help sodium hydroxide and hydrose form polyester dyed fabric to improve the fastness.NaOH 2-3g/l

Hydrose 1g/l at 60c for 20 mins

ii. Vatting and dyeing of cotton fibresThe hydrose and caustic soda react with vat dyes and make water solubility

Now vat dyes move to cotton fibres and dyeing is carried out

Add some amount salt for better exhaustion and raise the temperature for 80 C work at 45 mins

1. Oxidation This treatment is to fix the vat dye on cotton fabric by means of air oxidation or chemical oxidation.Chemical Oxidation recipe:Hydrogen peroxide (35%) 1-2 g/lAnionic detergent 0.5-1 g/l 2. SoapingThe dyed fabric washes with soap solution at boiling temperature for 30mins to remove unfixed dyes from the surface of the fabric.

Soap: 5 gpl

Temp: 100C

Time: 30 mins

3. Rinsing

The dyed fabric rinsed with hot water for 10 mins

Followed with cold water for 10 mins

4. Hydro extractor

To remove the water from dyed material with help of hydro extractor

To facilitate to drying

5. Drying

To dry the fabric with dryer or sun light.

One bath two-step process