Abstract:
The chemical stability of Disperse Navy Blue HGL (C. I. Disperse Blue 79) during the high-temperature dyeing process has been studied, when sodium lignin sulfonate (Lignosol D-30) is used as a dispersing agent. It was found that a part of the dye would undergo a secondary reaction, i. e. the bromine atoms replaced by hydrogen atoms, and the mixed products thus produced are able to dye the polyester and will accordingly change the regular color shade to some degree, an undesirable effect. Therefore, in using of a dispersing agent having reduction potential, if a good stability of the dye and a uniform shade are expected, the careful control of the proper dosage used and the pH value of the dyebath are both necessary.