Highly efficient cross-linking of reactive dyes in the amorphous zones of cotton fabric to simultaneously improve color and wrinkle properties

Abstract

Dyeing and wrinkle-finishing of cotton fabric is generally achieved through two steps, which consumes a lot of energy and generates a lot of colored wastewaters. In this study, we report an energy-saving and cost-reducing dyeing process that enhanced the cross-linking degree of double reactive group dye in the amorphous zone of cotton fabric, which in turn improved the wrinkle resistance of cotton fabric as well as the utilization of the dye. Compared with the traditional dyeing processes, the method could improve K/S values by 69.7%, dye fixation by 22.4%, and wrinkle recovery angle by 21.5% for dyed cotton fabric. The wrinkle recovery angle of the dyed cotton fabric increased with the increase of cross-linking degree. The cross-section of cotton fibers changed from a flattened girdle shape to an elliptical or rounded shape, and the mid-cavity structure became smaller or even disappeared. In addition, the cross-linked structures could hinder the degradation of fiber macromolecular chains by cellulases. This meant that the better the wrinkle resistance of the dyed cotton fabric, the lower the glucose content in the degradation solution. Compared with the conventional dyeing processes, this dyeing method could be saved 36.5% of dyes and 28.4% of alkali for per 1 kg of cotton fabric, and the cost could be saved by 56.1%. The dye concentration in the waste water was reduced by 43.2%. This method had certain advantages in terms of economic and environmental.