Studies In Pretreating Cotton Fabric With Scouring, Bleaching And Cationisation In One-bath And Salt-free Dyeing

To reduce the waste of alkali in the scouring and bleaching process of cotton fibers, and resolve the problems of salt and color contamination in reactive dyeing procedure, a new approach for combining scouring and bleaching process and cationisation is postulated and investigated. Accordingly, cotton fabric was scoured, bleached and catioinized with 2,3-epoxypropyltrimethylammonium chloride (Glytac-A) in one step process. After being scoured and bleached, greige cotton fabrics were directly cationized in the same bath. The Glytac-A-modified cotton fabrics could be dyed without salt addition and the utilization of the reactive dyes was improved.Based on the content of nitrogen and cations on the cotton the grafting conditions were then determined. The conditions for the one step process were that:4 g/L scouring agent,6 g/L hydrogen peroxide (30%),90 ? of the reaction temperature, for 60 min, after that adding 3 g/L sodium hydroxide and 30 g/L 2,3-epoxypropyltrimethylammonium was added to the above solution and the reaction temperature were kept 90 ? for 15 min. Whiteness test, weight loss rate test and water absorption test (Capillarity Effect test, water absorption rate and water droplets spreading time test) were used to analyze the practical property of greige cotton fabric. The test results showed that the performance of cotton fibers was in line with the national standards. The content of nitrogen and cations on the cotton were 0.0839% and 9.08 mg/g, respectively. ATR-IR was used to confirm the synthesis of graft Glytac-A. XRD, SEM, TGA and other methods were used to analyze its physical and thermal stability properties.At the same time, dyeing properties of cotton fibers were investigated. The dyeing effect of eight commercial dyes on the cationized cotton fabric was compared with that in traditional dyeing method. The commercial dyes were Reactive Blue KN-R, Reactive Red M-3BE, Reactive Yellow M-3RE, Reactive Red M-8B, Reactive Red M-2B, Reactive Blue M-2GR, Reactive Blue KN-G and Reactive Black KN-B. The fixation of the dyes on the Glytac-A modified cotton was 89.72%,96.74%,96.74%,96.34%,94.16%,86.07%,89.90% and 94.51%, respectively. Compared with that on the un-treated cotton, the dye fixation on the modified ones improved by 21.63%,30.73%,21.03%,37.26%,18.65%,18.24%,46.89% and 18.26%. The K/S increased as compared to those on the untreated cotton fibers. Colorimetric properties of the Glytac-A modified cotton were little changed compared with un-treatment cotton. The color fastness and dye penetrability of the cationized cotton fabrics were still favorable.