Study On Dyeing Behaviors Of Mixed Bifunctional Reactive Dyes With Wool/silk Fiber

Reactive dyes have bright color, high color fastness, and are widely used in wool and silk fiber. Although wool and silk are protein fibers, they have large differences both in physical structure and chemical composition. However, reactive dyes show great differences when dyeing with wool and silk, which brings a series of problems when dyeing with wool/silk multi-component fibers. By studying the reaction differences and dyeing difference of reactive dyes on silk and wool, this paper is to provide theoretical guidance on designing and developing new dyeing technology on wool/silk.This paper applied high performance liquid chromatography (HPLC) to analyse the hydrolysis characteristics of mixed bifunctional reactive dyes M-2GE on wool and silk and used simulation reaction experiment to study the nucleophilic reaction and reaction conditions of reactive dyes with nucleophilic group in wool and silk. Combined with the actual dyeing results of the mixed bifunctional reactive dyes on wool and silk, the differences and essence of dyeing performance between wool and silk were analyzed. Finally, use HPLC to analyze influence of sodium sulfate on reactive dyes hydrolysis and nucleophilic reaction between wool and silk. The main results showed that:When wool and silk were dyed by mixed bifunctional reactive dyes at low alkalescence condition, the relative content of hydrolysis product in wool bath was more than that in silk bath. Mixed bifunctional reactive dyes M-2GE reacted slowly with alcohol-hydroxyl groups, and the competition reaction with alcohol and water reaction was increased by pH value and temperature. Mixed bifunctional reactive dyes M-2GE reacted quickly with amino groups and phenol groups, the reaction rate of VS with amino groups was quicker than MCT. The reaction of mixed bifunctional reactive dyes M-2GE with amino groups was different from with phenol groups and MCT reacted quickly with phenol groups. The mixed bifunctional reactive dyes and hydrosulfide group had strong reactivity with dyes in the range of pH 4-10, and had different products at different pH. In weak acidic condition, hydrosulfide groups mainly reacted with MCT; in weak alkali conditions, hydrosulfide groups mainly reacted with VS. It could be concluded that: when wool dyed with mixed bifunctional reactive dyes, hydrosulfide group and amino groups on wool played a principal role. The reactivity between hydrosulfide and dyes in acidic condition might explain why reactive dyes had high fixation ratio on wool in acid bath. When silk dyed with mixed bifunctional reactive dyes firstly, MCT in mixed bifunctional reactive dyes reacted with a large of phenolic group on silk surface. Meanwhie, VS in mixed bifunctional reactive dyes also could react with amino groups on silk, in addition, and reactive dyes and silk might form a cross-linking mode. In addition, when wool and silk were dyed with reactive dyes, excess sodium sulfate made against dying, this could be attributed to dyes aggregation and the inhibition on the reaction with dye and fiber.