The dyeing mechanism of material with reactive dye takes place in 3 stages:-
- Exhaustion of dye in presence of electrolyte or dye absorption.
- Fixation under the influence of alkali.
- Wash-off the unfixed dye from material surface.
1. Dye absorption:
When fibre is immersed in dye liquor, an electrolyte is added to assist the exhaustion of dye. Here NaCl is used as the electrolyte. This electrolyte neutralize the negative charge formed in the fibre surface and puts extra energy to increase dye absorption. So when the textile material is introduces to dye liquor the dye is exhausted on to the fibre.
Fixation of dye means the reaction of reactive group of dye with terminal –OH or-NH2 group of fibre and thus forming strong covalent bond with the fibre and thus forming strong covalent bond with the fibre. This is an important phase, which is controlled by maintaining proper pH by adding alkali. The alkali used for this purpose depends on brand of dye and dyeing temperature. Here generally caustic soda, soda ash or NaHCO3 is used as alkali depending upon reactivity of dye. They create proper pH in dye bath and do as the dye-fixing agent. The reaction takes place in this stage is shown below: -
As the dyeing is completed, a good wash must be applied to the material to remove extra and unfixed dyes from material surface. This is necessary for level dyeing and good wash-fastness. It is done by a series of hot wash, cold wash and soap solution wash.
You have some articles on Reactive Dye:
- Introduction of Reactive Dye | History of Rective Dye | Uses of Reactive Dye
- Why So Called Reactive Dye | History of Reactive Dye | Which Fibers Can be Dyed with Reactive Dye?
- Chemical Structure of Reactive Dyes | Commercial Names of Reactive Dye | Properties of Reactive Dye | Popularity of Reactive Dye
- Classification of Reactive Dyes
- Hydrolysis of Reactive Dye | Removing Process of Hydrolysis of Reactive Dye | Why Low Affinity Reactive Dyes are Preferred for Dyeing?
- Stages/Steps Involved in Reactive Dyeing
- Stripping Process of Reactive Dye
- Important Factors of Cold Brand Reactive Dye | Factors of Reactive Dye
- Different Methods of Reactive Dye Application | Pad-batch Method | Pad Dry Method | Pad Steam Method
- Knit Dyeing with Reactive Dyes(Hot Brand) | Knit Dyeing with Hot Brand Reactive Dyes