Excellent fixation and color fastness of nylon fibers dyed with low-water-soluble reactive dyes based on the reactivity and stability of vinyl sulfone

Reactive dyes in nylon dyeing have been associated with utilization inefficiencies despite their high color fastness. A potential solution to this issue involves combining the benefits of reactive dyes and milling acid dyes to obtain low-water-soluble reactive dyes (LWSRDs), which can stain and fix to nylon fibers under neutral conditions. To identify a suitable functional group for LWSRDs, six model dyes comprising one vinyl sulfone and five monochloro- s-triazines were prepared and reacted with glycine or hydrolyzed to simulate the fixation progress on nylon fibers. The results show that vinyl sulfone exhibited sufficient reactivity with glycine, and ∼3% hydrolysis over 90 min. Consequently, vinyl sulfone was considered a superior functional group for LWSRDs. Based on these results, four LWSRDs with monofunctional groups were synthesized and used for dyeing nylon 6 microfibers. Notably, these dyes exhibited fixation of >91% and demonstrated exceptional color fastness against washing and rubbing, exceeding grade 4. These results underscore the potential of LWSRDs as highly efficient and effective dyes for nylon, offering a solution to the limitations associated with conventional dyeing techniques.