Different Methods of Reactive Dye Application | Pad-batch Method | PadDry Method | Pad Steam Method

Different methods of reactive dye application:

1) Pad-batch method.

Pad batch processes are of two types-
a) Pad (alkali)-batch (cold) process.
b) Pad (alkali)-batch (warm or hot) process. 

2) Pad dry method
3) Pad steam method.

1) Pad-batch method

a. Pad (alkali)-batch (cold) process.

Figure: Pad-batch method

Steps:
1) The fabric is first padded in a padding mangle with reactive dye in presence of an alkali.
2) The padded fabric is rolled in a batch and the batches are wrapped by polyethylene sheets and stored in wet condition for 1-24 hours at 200-300C in a room.
3) During the storage period, the rolls may be kept slowly rotating to prevent seepage of the dye liquor.
4) After storing time is finished fabric is washed in a rope washing machine to remove the unfixed dye from fabric surface.

b. Pad batch (hot) process:

Figure: Pad batch (hot) process

Steps:
1) The fabric is first padded in a padding mangle with reactive dye in presence of an alkali.
2) The fabric is then passed in between infrared heater to preheat the padded fabric to 500C to 900C.
3) The fabric is then batched on a large diameter roller in a hot chamber. The batching is done under controlled conditions of temperature and humidity for a sufficient time to ensure diffusion and fixation of the dye in the fibre. During this period the batch is kept slowly rotating to avoid the seepage of dye liquor.
4) The cloth is then washed in a rope washing machine to remove the unfixed dyes.

2) Pad dry method:

Figure: Pad dry method

Steps:
1) Fabric is first padded in a padder with reactive dye in presence of an alkali.
2) Padded fabric is then passed through a squeezing roller into a dryer. As a dryer cylinder, stenter etc may be used. During drying due to higher temperature fixation of dye in fibre increases and at the same time water is removed by evaporation.
3) After drying fabric is washed in a washing machine to remove unfixed dye.

3) Pad steam method:

Figure: Pad steam method

Steps:
1) Fabric is first padded in a padder with the dye.
2) It is then passed through between two squeezing roller in a dryer. Drying should be done slowly; otherwise precipitation of dye due to quick removal of water may take place leading to lower color value.
3) After coming out from dryer fabric is padded in a padder containing salt and alkali. Due to salt exhaustion of dye takes place and due to alkali fixation occurs.
4) Fabric then passed through a steamer where it is kept for 15-19 second. Due to high temperature here fixation rate increases.
5) In this step fabric is washed in a washing machine to remove the unfixed dye.