Reuse of reactive dyebaths - Dyeing nylon 6,6, nylon 6, and wool with hydrolyzed reactive dyes

The dyeability of hydrolyzed reactive dyes was studied. The dyes examined were C.I. Reactive Black 5, Yellow 3, Red 2, and Blue 19. C.I. Acid Black 1 and Blue 25, which have the same parent structures as the Reactive Black 5 and Blue 19, were also tested as a comparison to the dyeing behavior of the hydrolyzed reactive dyes. The fibers tested were nylon 6,6, nylon 6, and wool. The effects of dyeing conditions (such as temperature, pH, and types and concentrations of electrolytes) with hydrolyzed reactive dyes were evaluated. The results show that the hydrolyzed reactive dyebath, the reactive dyebath after cellulosic dyeing, could be used as an acid dyebath. Fibers dyed with hydrolyzed reactive dyes had similar washfastness and lightfastness as ones dyed with acid dyes of similar dye structures.