Reactive dyes

摘要

IT took almost 100 years after the synthesis of the first artificial dye for the reactive dyes to see the limelight. The reactive were so named because they enter into a chemical reaction with the textile substrate. Before the advent of reactive dyes, the coloration of cotton was achieved by direct, vat, azoic, sulphur, solubilised vat, solubilised sulphur, and basic dyes (after mordanting). In all these cases dyes were held onto the textile substrates by different attractive forces like electrostatic interactions, hydrogen bonding, non-specific interactions like van der Waals forces, and H-bonding The possibility of attaching dyes with fibers with a covalent bond has long been attractive to dyestuff chemists because attachment of dye molecules to the fibers by physical adsorption and mechanical retention have the disadvantages of high cost, low wet fastness and elaborate dyeing methods (except direct dyes).