Reactive dyes form a covalent bond between fibre and dye. They are classified depending on the reactive group present and the optimized conditions in which they are best used. Depending on the type of reaction, the reactive dyes are broadly divided in to two categories:
- Dyes reacting through Nucleophilic substitution reactions
- Dyes reacting through Nucleophilic addition reactions.
A. Dyes reacting through Nucleophilic substitution reactions:
(1) Dichlorotriazynilamino types of dyes
These are more reactive than monochloro type of dyes and require lower temperature and milder alkali for dyeing and fixation. These are known as Cold brand reactive dyes.
(2) Monochlorotriazynylamino type of dyes
These require higher temperature and stronger alkali for dyeing and fixation. These are called hot brand reactive dyes.
About the Authors:
The authors are associated with the Textile & Engg. Institute, Ichalkaranji.