Continuous Pad Dyeing of Cotton Fabric in a Non-Aqueous Medium for Realizing Ultra-High Fixation and Washing-Free

In traditional water-based dyeing system, a low fixation of reactive dye requires six to ten times washing after dyeing, which consumes a lot of water and results in huge dyeing effluent. To alleviate this issue, the development of a sustainable dyeing technology of cotton textile is essential. In the present investigation, silicone non-aqueous medium was employed to improve the fixation of dye with a pad-dyeing process under the optimized dyeing parameters. The appropriate washing-free dyeing conditions were recommended as follows: the padded fabric was placed at 105 °C for 15–30 s to complete pre-drying to decrease the water content rapidly, and then fixed in non-aqueous medium for 80–90 s at 95 °C. After dyeing, the dyed fabric was treated with 30 g /l fixing agent through pre-dried at 80 °C and baked at 160 °C. The results indicated that the final fixation of dye was above 95 %, and the dry rubbing fastness of dyed cotton fabric can reach grade 5. Moreover, the wet rubbing fastness and washing fastness of dyed cotton fabric can reach grade 3–4 and 4, respectively. Therefore, it can obtain the washing-free dyeing of cotton fabric with reactive dye. If the washing procedure was omitted in the industrial application, the environmental cost of cotton dyeing would be greatly decreased. This method provides a substantial reduction in wastewater effluent, which will be considerably potential for industrial application.