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Here the dye contains a reactive group and this reactive group makes covalent bond with the fibre polymer and act as an integral part of fibre. This covalent bond is formed between the dye molecules and the terminal –OH (hydroxyl) group of cellulosic fibres on between the dye molecules and the terminal –NH2 (amino) group of polyamide or wool fibres.
Reaction of Reactive Dye:
Here, D= dye part.
Wool = wool polymer.
Cell = cellulosic polymer.
Reasons for so named:
Reactive dyes are so called because this is the only type of dye, which has reactive group, and that reactive group reacts chemically with fibre polymer molecules and form covalent bond. This covalent bond is formed between the reactive group and terminal –OH (Hydroxyl) group of polyamide and wool fibre or between reactive group and terminal -NH2 (Amino) group of cellulosic fibre polymer. The strength of this covalent bond is more than ionic bond, hydrogen bond and Vander Waal’s force of attraction. Thus the reactive group becomes an integral part of the fibre.
For this reasons the dyes are so called. They are also called ‘fibre reactive group’.
History of Reactive Dye:
On the occasion of 100 year’s celebration of synthetic dye manufacturing, two chemists of ICI company (UK) named Stephen and Rattee tried to manufacture a new dyestuff. Thus they succeed to invent a new dye in 16965, which was named REACTIVE DYE. This was manufacture for dyeing cellulosic fabrics. The first three reactive dyes were PROCION YELLOWR, PROCION BRILLIANT RED 2B and PROCION BLUE 3G.for this effort they were awarded gold medal of the society of dyes and colorists for the year 1960.
Which Fibers can be dyed with Reactive Dye:
By reactive dyes the following fibres can be dyed successfully:
1) Cotton, rayon, flax and other cellulosic fibres.
2) Polyamide and wool fibres.
3) Silk and acetate fibres.
It covers a wide range of color spectrum and includes shades varying from bright to heavy dark like,
a. Violet
b. Blue
c. Green
d. Red
e. Black
f. Yellow
g. Etc.
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