Preparation of cationic viscose and its salt-free dyeing using reactive dye

The traditional dyeing process of reactive dyes requires a large amount of inorganic salts to accelerate the combination of dyes and textiles, which leads to substantially more water pollution. In this work, we used a quaternary ammonium-type cationic modifier, 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC), to modify the viscose acetal fibre before the dyeing process. After the modification, reactive dyes were dyed without any inorganic salt. Then the fabric was finished with a commercial wet rubbing fastness enhancer, FM-8, to improve the colour fastness. The modified viscose acetal fibre was characterised by Fourier Transform-infrared spectroscopy and scanning electron microscopy. The results showed that viscose acetal fibre was modified successfully by CHPTAC and that the physical structure did not noticeably change following the modification. The optimum process was determined by establishing the ideal amount of modifier and the modification temperature, as well as the concentrations of sodium hydroxide and soda ash. The results show that the most suitable parameters were 80 g/L for the modifier dosage, a modification temperature of 70 degrees C, 20 g/L of sodium hydroxide and 10 g/L of soda ash. The wet rubbing fastness was grade 4-5 after finishing and dyeing. The exhaustion percentage was significantly higher than that for traditional dyeing, and the K/S and dyeing uniformity were both higher than traditional salt dyeing.

Automated summary

In this study, a quaternary ammonium-type cationic modifier was used to modify the fiber and achieve reactive dyes dyeing without inorganic salt. The wet rubbing fastness was improved by a commercial enhancer. The optimal parameters for the modification were determined, and the modified fiber showed better wet rubbing fastness, exhaustion percentage, K/S value, and dyeing uniformity compared to traditional dyeing.