The wash-off of reactive dyes on cellulosic fibres part 2. Monochlorotriazinyl dyes on cotton

Abstract

One monochlorotriazinyl and two bis-monochlorotriazinyl dyes were applied to cotton fabric at 1, 2 and 4 % omf and the dyeings then washed-off using tap water, sodium carbonate and five commercial surfactants, the latter in both the presence and absence of sodium carbonate. The concentration of sodium carbonate was varied and its effects on both the extent of dye removal from the dyeings and the wash fastness of the dyeings were determined. Sodium carbonate, as well as each of the five surfactants used, was more effective in removing dye than tap water alone; the use of each of the surfactants in conjunction with sodium carbonate enhanced the effectiveness of the surfactants in removing unfixed dye. Dyeings which had been washed-off using sodium carbonate alone or using the five surfactants in the presence of alkali, were found to exhibit superior wash fastness to dyeings that had been washed-off using tap water only or each of the surfactants alone. In general, it appears that the use of surfactants in the wash-off of monochlorotriazinyl reactive dyes may be unnecessary and that an adequate level of wash-off can be achieved using 2 g litre −1 sodium carbonate alone. The avoidance of surfactants in wash-off and the alternative use of sodium carbonate may result in a process that is not only more cost-effective but also more environmentally friendly.