Studies On Salt-free Dyeing Of Reactive Dyes

Cationic starch of quaternary ammonium type with high DS, polyamines and polyamines grafted with UV-absorber BP-4 were applied as cationic agents of cotton in salt-free dyeing of reactive dyes. Quaternary ammonium groups of cationic starch and aminocations within polyamines in a wide range of pH were functional groups for dye adsorption. High fixation was achieved in salt-free dyeing, and pollution problem resulted from salt usage in conventional dyeing process was solved.Dip-pad-bake process was employed in pretreatment of cotton with native cationic starch with high DS. Influence of pretreatment conditions on dye fixation was investigated. The results showed that good dye fixation compared with that of conventional dyeing was obtained, but level dyeing was not achieved. Ultrasonic was used to reduce viscosity of native cationic starch to improve levelness of dyeing, but unsatisfactory dye fixation was got.Cationic starch hydrolyzed by hydrochloric acid was then applied;dip-rinsing process and dip-pad-bake process were used for pretreatment of cotton. Effect of pretreatment conditions on both adsorption amount of cationic starch and dye fixation was examined. Dyeing mechanism was discussed and the performances (including color, fastness, finishing properties and dye penetration) of the dyed cotton fibers were investigated. Recycle utilization of cationic starch was also examined.Polyvinylamine and polyallylamine were applied in pretreatment of cotton in salt-free dyeing process. Dip-pad-bake and dip-rinsing processes were used for pretreatment of cotton. Effect of pretreatment conditions on both adsorption amount of polyvinylamine and dye fixation was examined. Dyeing mechanism was discussed and the performances (including color, fastness, finishing properties and dye penetration) of the dyed cotton fibers were investigated. Recycle utilization of polyvinylamine was also examined.Chlorosulfonyl-containing UV absorber CBP-4 was synthesized by the reaction of the corresponding UV absorber BP-4 and thionyl chloride in the presence of a catalytic quantity of DMF. Its structure was confirmed by IR, ~1H NMR and MS spectroscopies.Two BP-4 grafted polyamines-PVAmBP-4 and PAAmBP-4 were synthesized from the prepared CBP-4 and their applications including effect on dye fixation and transmissivity of cotton were investigated.