Reactive Dyes for Nylon*

Conventional dyes for nylon have suffered, hitherto, from the disadvantage that those of good fastness properties do not readily cover the chemical and physical irregularities of the fibre, whilst those which are free from these defects have rolatively low fastness properties. A new range of reactive dyes for nylon has now been developed. They are disperse dyes and can be applied in an unreaetive form under acid conditions, when they possess the level–dyeing properties of disperse dyes. When the bath is made mildly alkaline, reaction occurs between dye and fibre, and a fast, level dyeing is obtained. It has been found that these dyes react both with the amine end–groups and with the amide groups in the fibre, so difficulties associated with saturation of amine end–groups are not encountered. Rates of dyeing and fixation of the dyes have been determined both separately and in mixtures and it is shown that the dyes are compatible for dyeing as mixtures. Rate–of–dyeing curves indicate that these dyes behave as medium–to–slow dyeing disperse dyes. As with Procion dyes when applied to cellulose, a side–reaction occurs in the dyebath, and in this case the deactivated dye remains on the fibre after the soaping treatment. Since, however, the unfixed dye has fastness properties at least equal to those of conventional disperse dyes, this small proportion can be tolorated without undue loss of fastnoss. For the first time a range of dyes is available for dyeing nylon to level, attractive colours with good wet fastness properties using a simple technique and conventional dyeing machinery.