The enhancement of wool reactive dyes ink-jet printing through air plasma pretreatment

Abstract

Ink-jet printing is a clean and high-definition printing method for wool fabrics. However, due to the existence of scale layers, the dyes were hardly absorbed into the wool fibers, resulting in poor printing quality. In this work, a green and efficient air plasma pretreatment method was proposed to improve ink-jet printing performance of wool fabrics using reactive dye inks. The results showed that the wool surface was etched after plasma treatment, which led to the increased contact area between wool fiber and dyes. Meanwhile, due to the introduction of more oxygen-containing functional groups on the fiber surface, and part of the –SH and –S-S- were oxidized into –S-O-, the wettability of wool was obviously enhanced with the contact angle decreasing from 135° to 27.5°. The breaks of C–C and C–N bonds resulted in the increase of binding sites between reactive dyes and wool fibers. Because of the above changes, the inks were easily absorbed into the fiber, which promoted the covalent binding of dyes and fibers. As a result, compared with the untreated wool fabric (K/S value of 14.64), the wool fabrics treated by air plasma for 3 min obtained a wonderful printing effect with a K/S value of 22.34. This pretreatment method provides an environmental and efficient approach for the improvement of wool fabrics ink-jet printing performance.