A vacuum-dehydration aided pad-steam process for improving reactive dyeing of cotton fabric

Abstract

The serious colored effluent pollution and high production costs generate new requirements of enhancing dye utilization and reducing energy consumption in reactive dyeing of cotton. A vacuum-dehydration aided pad-steam process with high dye utilization and energy efficiency potential to dye cotton fabric with reactive dye was preliminarily trialed on this purpose. The effects of steaming time, sodium carbonate amount and dye concentration on reactive dyeing were investigated. The color build-up property and rubbing fastness of dyed fabrics were also analyzed. The results show that the steaming time of 3 min and 30 g/L of sodium carbonate were appropriate for dyeing cotton fabric with 25 g/L of C. I. Reactive Black 5. The dye penetration into cotton fibers became poor with increasing dye concentration. Cotton fabrics dyed with the vacuum-dehydration aided pad-steam process had maximum 12% higher K/S value than the fabrics dyed with the conventional pad-steam process, meaning that fewer quantities of dyes could produce higher color strength, which is beneficial to the environmental protection, saving dyes and lowering costs. Rubbing fastness ratings of the dyed fabrics reached equal to or above 3 using the proposed dyeing process, which is suitable for the end use of the fabric.