In order to facilely achieve pretreatment and salt-free dyeing of greige knitted cotton fabrics, a combinative scouring, bleaching, and cationization pretreatment of the fabrics is designed in this study. The fabrics are first treated in a bath containing commercial scouring and bleaching agents, and then glycidyltrimethylammonium chloride (GTA) is directly added into the bath to achieve cationization of the fabrics. Utilization of the alkaline and high-temperature conditions in scouring and bleaching process, cationization can facilely proceed in a short time. Optimal pretreatment conditions are as follows: greige knitted cotton fabrics are treated in a bath containing 4 g/L scouring agent and 6 g/L 30% hydrogen peroxide at 90 °C for 60 min, and then 30 g/L GTA and 3 g/L sodium hydroxide are added in the bath for another 15 min treatment. Fiber performances, including whiteness, water absorptivity, diffusion time, and capillary effect, are tested and evaluated. X-ray diffraction analysis, surface morphology, and thermal analysis of the pretreated cotton are also investigated and compared with that treated only with scouring and bleaching agents. Much higher dye fixation and color yield could be realized on the pretreated cotton in salt-free reactive dyeing. Colorimetric properties of the dyes are studied and good colorfastness of the dyes on the cationic fabrics are obtained. All of the above results show promising prospects of this combinative pretreatment in real application.
Keywords: cationic cotton; combinative pretreatment; reactive dyes; salt-free dyeing.