Mechanism of cellulose staining in disperse dyeing of polyester/cotton blended fabrics in non-aqueous medium

A recent development in non-aqueous two-step (disperse and reactive) dyeing technology, minimizes water usage, eliminates the need for salt, and avoids the production of wastewater during the dyeing of polyester/cotton blend fabrics. However, an issue of color staining on cotton fibers during the disperse dyeing process has been observed. To address this issue, the mechanisms of dyeing polyester fibers and staining cotton components by disperse dyes in this process were investigated, using C.I. Disperse Red 177 as an example. It was observed that the adsorption isotherm of the disperse dye on cotton fibers resembled the Freundlich type. Moreover, as the temperature increased, the affinity between the dye and the cotton component decreased, thereby reducing the staining rate of disperse dyes on cotton fibers. High performance liquid chromatography (HPLC) analysis revealed that 22% of disperse dyes absorbed by cotton components were hydrolyzed dyes, while 78% were original dyes. This was attributed to the greater interaction energy between the original dye and the cotton fiber compared to the hydrolyzed dye. The primary interaction between disperse dyes and cotton fibers was identified as dispersion forces. From investigating the uptake, staining and hydrolysis performance of disperse dyes, the study sheds light on the mechanism of color staining behavior of disperse dye on cotton fibers, demonstrating the potential of a one-bath two-step dyeing process in non-aqueous medium dyeing system.