Preparation of cationic cotton with two-bath pad-bake process and its application in salt-free dyeing

Cationic cotton was prepared by a designed two-bath pad-bake process with 3-chloro-2-hydroxypropyltrimethylammonium chloride as cationizing reagent to realize recycle utilization of the reagent and continuous processing of cationization. Experiments showed that 8.0% (o.w.bath) of the reagent, 1:1 of molar ratio of sodium hydroxide to the reagent, 60 °C and 6 min of baking temperature and time were selected for cationization and the obtained cationic cotton was suitable for application in salt-free reactive dyeing. The structures of both the untreated and cationic fibers were investigated by X-ray diffraction and scanning electronic microscopy. Higher dye utilization and color yields could be realized on the cationic cotton than that on the untreated one in the conventional dyeing. Levelness dyeing and good fastness properties of the dyes on the cationic fabrics were obtained. Besides, colorimetric properties and mechanical strength of the dyed fabrics were both evaluated to show applicability of this preparation process of cationic cotton.