Sulphur dyes on nylon 6,6 - part 1: the effects of temperature and pH on dyeing

Nylon 6.6 was dyed with five commercial sulphur dyes at different pH values and various temperatures. It was found that over the pH range 6-12, maximum colour strength was achieved at pH 7 and the colour of the dyeings was influenced by the pH at which dyeing had been carried out. The latter observation was explained in terms of the effect of pH on the state of reduction of the dyes and their subsequent oxidative condensation. The five dyes varied in terms of the effect of dyeing temperature, over the range 50-120degreesC, on colour strength. Generally, within the range 70-98degreesC, temperature had little effect on the colour of the dyeings whereas both lower dyeing temperatures (50 and 60degreesC) and, especially, higher temperatures (110 and 120degreesC) resulted in colour change. In terms of wash fastness, dyeing temperature had little influence on shade change or staining of adjacent multifibre material. With the exception of the black dye used, the dyeings displayed poor fastness to light; dyeing temperature had little effect on light fastness. (C) 2003 Elsevier Science Ltd. All rights reserved.