Investigation into the Blocking Effect of Reactive Dye Combinations in Exhaust Dyeing of Cotton

Abstract

The blocking effect of reactive dye combinations during the exhaust dyeing of cotton was studied using C.I. Reactive Yellow 176, C.I. Reactive Red 239 and C.I. Reactive Black 5. In the exhaust dyeing of binary reactive dye combinations, reverse order of dyeing was carried out at the dye concentration of 1%owf. After the shade of dyed cottons were evaluated, we found that the combination of C.I. Reactive Yellow 176 and C.I. Reactive Black 5 exhibited a blocking effect. The blocking took place readily in the dyebath. Therefore, C.I. Reactive Blue 250 was used to replace C.I. Reactive Black 5 because of the similarity of their chromophores and reactive groups. The results showed less blocking effect, indicating low interaction between the dyes in the combination.