A study of reusing vinyl sulfone based reactive dye for dyeing cotton fiber

Reactive dye is a popular dye for dyeing cotton fiber due to its very good color fastness which is explained by the formation of covalent bond between dye and fiber. In this study, practicality of reuse of reactive dye by compensating for the hydrolyzed part of the dye solution is examined. A monofunctional dye (vinyl sulfone type) was used and it was found that dyeing cotton fiber with reused dyebath is possible. Since bifunctional dye can improve the chance of dye-fiber bond formation, vinyl sulfone based bifunctional reactive dyes were also selected in this study. Three types of bifunctional dyes were used and they basically share the same vinyl sulfone group; other reactive groups are monochlorotriazine, dichlorotriazine and vinyl sulfone. Such dyes were chosen in order to compare their respective efficiencies under the effect of one common reactive group. The aim of this study was to compare the effect of hydrolyzed and unhydrolyzed proportions of mono-and bifunctional reactive dyes on cotton fiber and study the possibility and efficiency of the two different reuse dyebath systems.