Bifunctional amphoteric polymer-based ecological integrated retanning/fatliquoring agents for leather manufacturing: Simplifying processes and reducing pollution

The leather industry is moving towards the goals of reducing pollution, simplifying manufacturing processes, and achieving sustainable development. However, there are still challenges in current leather processing methods that make achieving these goals difficult, including low chemical absorption rates, generation of large amounts of contaminated waste, and complex manufacturing processes. Herein, an amphoteric polymer was compounded with castor oil to create an integrated “retanning and fatliquoring” agent (ARFMDD) for post-tanning wet processing of ecological chromium-free organic tanned leather. The amphoteric polymer was prepared by free radical polymerization of 1-Dodecyl-3-vinyl imidazole bromide, dimethyl aminoethyl methacrylate, and maleic anhydride. Comprehensive characterization showed that ARFMDD increased the TWS-tanned leather fullness, softness and increased the dye absorptivity up to 98.33%. Moreover, the treated leather had a bright color and high color fastness after dyeing. Impressively, compared to traditional dyeing processes, omitting the acid fixation step for ARFMDD treated leather did not affect the leather performance. The total organic carbon content in waste from the non-acid fixation dyeing process was significantly reduced by 66.49%. The proposed integrated “retanning and fatliquoring” amphoteric polymer system for post-tanning wet processing of leather realizes the overall goals of reducing pollution, increasing the chemical absorption rate, and simplifying the process as well as promoting the sustainable development of the leather industry.