Preparation of quaternary ammonium lignosulfonate modified UV resistant polyurethane and its application in leather dyeing.

Applying cationic waterborne polyurethane (CWPU) in the leather color-fixing process can improve the dyeing rate and enhance color fastness. However, under prolonged exposure to sunlight, CWPU will age and degrade and the leather will fade in color, become stiff and crack easily. In this study, an Ultraviolet absorber was introduced into cationic waterborne polyurethane (UVCWPU) and quaternary ammonium Lignosulfonate (QLS) was prepared by quaternization. Quaternary ammonium Lignosulfonate/UV-resistant waterborne polyurethane (QLS/UVCWPU) composite was prepared by the blending method. A one-way experiment was carried out to investigate the effect of the additional amount of quaternary ammonium reagent on the degree of modification of QLS, and the results showed that when the ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMAC) to LS was 7:1, the isoelectric point of the prepared QLS reached 6.65, and the content of N was 4.32 % so that the quaternary ammonium lignosulfonate modification was successful. QLS/UVCWPU was used to solidify the leather at pH 4.0 and a dosage of 4 %. The dye absorption rate of the leather increased to 97.3 %, the K/S value of the dyed gray leather reached 28.51, the color fastness to dry rubbing was improved to grade 5, and the color fastness to wet rubbing was up to grade 3 and enhancing the color fastness to sunlight, slowing down the effect of ultraviolet aging, and improving the antimicrobial properties of the leather.