Fibre Reactive Dyes and Insoluble Azo Dyes

Fibre Reactive Dyes

Fibre Reactive Dyes attach themselves to the fibre by an irreversible chemical reaction. The dyeing is fast and the colour is retained for a long time. The bonding is through the substitution of leaving group of dye via the hydroxy or amino group of fibres like cotton, wool or silk


Insoluble Azo Dyes

Insoluble Azo Dyes are obtained by coupling phenols, naphthols, arlamines, amino naphthols adsorbed on the surface of a fabric with a diazonium salt. Over 60% of the dyes used are Azo dyes. Cellulose, silk, polyester, nylon, polypropylene, polyurethanes, poly acrylonitriles and leather can be dyed by using these dyes. Azo dyes also find use in cosmetics, drugs, biological stains and as indicators in chemical analysis. Use of such dyes for colouring of food stuffs is not permitted.

To know classification of dyes visit Chemicals in every day life: Dyes