Azodisperse Dyes with Photochromic Mercury(II)-Dithizonate Moiety for Dyeing Polyester, Nylon and Cellulose Triacetate Fibres: Dyes Based on N-Substituted Aromatic Amines as Coupling Components

160-163Twelve photochromic azodisperse dyes based on N-substituted and N,N-disubstituted derivatives of anilines and m-substituted anilines were synthesized and their dyeing performance on polyester, nylon and cellulose triacetate fibres was assessed. All the dyes showed moderate to good fastness to light and very good to excellent fastness to washing, rubbing, perspiration and sublimation. The dyed fibres on exposure to bright sunlight or a light of suitable wavelength showed a very good photochromic effect giving various shades. When the fibres were removed from the sunlight the colour returned to the original shade. The time required for this return depended on the intensity of incident light, ambient temperature and the moisture content of fabric. Polyester fibres required a longer duration for attaining the original shade but rapid change was observed by ironing the, cloth. The duration the fibre required to attain the original shade could be reduced to 3 min for nylon and cellulose triacetate and to 2-3 min for polyester fibres by keeping them in an oven at 80°C and 100°C respectively.