Hydrogen-Bond-Assisted Dye-Incorporated Waterborne Poly( urethane-urea) (WPU) for an Environment-Friendly Textile Dyeing Process

To propose a green dyeing strategy permitting the incorporation of chromophores via the promotion of physical bonding and a simple sewage processing procedure, a strategy for increasing the reactivity of a conventional disperse dye, namely, 1-amino-4-hydroxy-2-phenoxyanthraquinone (Disperse Red 60, R60), to isocyanate groups and miscibility with waterborne poly(urethane-urea) (WPU) was reported. The modified dye R60-OH was prepared by the alkylation of 3-bromopropan-1-ol. Subsequently, R60-OH was reacted with the trifunctional isocyanate (named R60-O-THDI), which provided additional hydrogen bonds between the dye and the polymer chain and rendered better color fastness. Polyester, nylon, and cotton fabric coated with R60 and R60-O-THDI-incorporated WPUs were investigated by colorimetric analysis, washing tests, and rubbing color fastness. R60-O-THDI exhibited the best rubbing and washing color fastness, indicative of a simple method to fabricate a water-based dye ink without grafting a chromophore onto a polymer backbone via the promotion of physical bonding. The proposed green dyeing strategy also permitted a simple sewage processing procedure to recover polyurethane from the suspension by changing the pH, rendering better color fastness on textiles, as well as less wastewater production.