Preparation of a ricinoleic acid modified amphoteric polyurethane for leather cleaner and simplifying production

Realizing green processes in wet finishing (including tanning, retanning, and fatliquoring) has become a big concern in the leather industry. Although the development of chrome-free tanning agents has made great contributions to the cleaner production of leather in recent years, the retanning and fatliquoring processes matched with this promising system still have many disadvantages, such as low compatibility, complex processes, and high pollution. Here, a novel multifunctional amphoteric polyurethane (RAWPU, an amphoteric polyurethane modified by ricinoleic acid) was synthesized and applied in the processing of chrome-free tanned leather. As a result, this product has not only the retanning characteristics of leather but also the lubrication characteristics of leather, thus integrating the traditional retanning and fatliquoring processes into one step. In addition, the hygienic performance of leather treated with RAWPU is better than that of the leather treated by commercial agents. More interestingly, compared with commercial agents which are nondegradable, RAWPU synthesized in this work easily degrades. This work is of great significance to the practical production of leather.