Effect of an Amphoteric Chromium-free Polymer RetanningAgent with Reactive Aldehyde Groups on Collagen Fibers

A chromium-free amphoteric polymer retanning agent was prepared by free radical polymerization reaction of undecylenic aldehyde (UAL), acrylic acid (AA) and dimethyl diallyl ammonium chloride (DADMAC) as raw materials. The structure of amphoteric polymer retanning agent was characterized by FT-IR and H-1-NMR. Amphoteric polymer retanning agent was applied to the retanning of vegetable-tanned light leather to investigate the binding ability of crust leather to anionic dyes, fat liquoring agent and physical-mechanical properties of the crust leather. The results showed that the synthesized amphoteric polymer retanning agent was successfully prepared. The application trial indicated that the amphoteric polymer retanning agent can improve the binding capacity between leather and anion dye and fat liquoring agent in the retanning process. The dye absorption rate of the crust leather was up to 99.58% and the dyeing liquor was clear. Furthermore, color of the crust leather was uniform and full and its K/S value and dry-wet rub fastness, thickening rate and physical-mechanical properties were higher than that of the retanned leather by acrylic resin retanning agent. In addition, the crust leather after retanning with amphoteric polymer retanning agent has good softness, and the absorption rate of fat liquoring agent was 99.62%. The above results showed that amphoteric polymer retanning agent possessed the good retanning property in vegetable tanned sheep garment leather.