A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent. However, to achieve satisfactory resultant leather, the retanning process that is compatible with this emerging tannage needs to be investigated systematically. This paper aims to explore the interaction between the bimetal complex tanned wet white and retanning agents. The isoelectric point (pI) of wet white was 7.2, which was nearly the same as wet blue. The electropositivity of wet white was even higher than that of wet blue during post-tanning processes, resulting in higher uptake rate of retanning agents. The distribution of various retanning agents in wet white was analyzed by pI measurement of layered leather and fluorescent tracing technique. The retanning agents were unevenly distributed throughout the cross-section, which might be an important restriction factor in obtaining satisfactory organoleptic properties of the crust leather. This fact is mainly due to the strong electrostatic interaction between anionic retanning agents and wet white. Applying a high dosage of multiple retanning agents in a proper sequence of addition benefited the full penetration of retanning agents in leather matrix and thus improved the organoleptic properties of crust leather. This work provides guidance for optimizing retanning process of the wet white leather.

中文翻译：

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复鞣剂与新型双金属络合物鞣剂鞣制的湿白之间的相互作用

基于新型的Al-Zr双金属络合物鞣制剂，开发了一种有前途且实用的无铬鞣制系统。但是，为了获得令人满意的合成皮革，需要系统地研究与这种新兴鞣制工艺兼容的复鞣工艺。本文旨在探讨双金属络合物鞣制的湿白与复鞣剂之间的相互作用。湿白的等电点（pI）为7.2，几乎与湿蓝相同。在鞣制后的过程中，湿白的电正性甚至高于湿蓝的电正性，从而导致复鞣剂的吸收率更高。通过分层皮革的pI测量和荧光示踪技术分析了湿态白中各种复鞣剂的分布。复鞣剂在整个横截面上分布不均匀，这可能是获得令人满意的硬皮感官特性的重要限制因素。这个事实主要是由于阴离子复鞣剂和湿白之间的强静电相互作用。以适当的添加顺序施用高剂量的多种复鞣剂有利于复鞣剂在皮革基质中的完全渗透，从而改善了结皮的感官特性。这项工作为优化湿白皮革的复鞣过程提供了指导。这个事实主要是由于阴离子复鞣剂和湿白之间的强静电相互作用。以适当的添加顺序施用高剂量的多种复鞣剂有利于复鞣剂在皮革基质中的完全渗透，从而改善了结皮的感官特性。这项工作为优化湿白皮革的复鞣过程提供了指导。这个事实主要是由于阴离子复鞣剂和湿白之间的强静电相互作用。以适当的添加顺序施用高剂量的多种复鞣剂有利于复鞣剂在皮革基质中的完全渗透，从而改善了结皮的感官特性。这项工作为优化湿白皮革的复鞣过程提供了指导。以适当的添加顺序施用高剂量的多种复鞣剂有利于复鞣剂在皮革基质中的完全渗透，从而改善了结皮的感官特性。这项工作为优化湿白皮革的复鞣过程提供了指导。以适当的添加顺序施用高剂量的多种复鞣剂有利于复鞣剂在皮革基质中的完全渗透，从而改善了结皮的感官特性。这项工作为优化湿白皮革的复鞣过程提供了指导。