Application of Nonionic Gemini Aliphatic Polyurethane Surfactant for Improving the Performance of Vegetable Tanned Leather

Abstract

Vegetable tanned leathers with good embossing, air permeability, natural look and pleasing firm handle properties have applied in many goods with multiple uses. However, the performances of vegetable tanned leathers still need a further improvement. In this work, a kind of nonionic gemini aliphatic polyurethane surfactants (GPUs) with different hydrophobic chain lengths as a retanning agent combined with polyacrylic acid (PAA) for condensed tannin tanned leathers to improve their performances. The effects of the alone or combined use of the PAA and GPU, the hydrophobic chain length of GPU, and the offer percentage of retanning agent were studied by evaluating the organoleptic properties, shrinkage temperature, mechanical properties of the obtained leathers. The best performance was found in the leather retanned with PAA and 12-GPU-550 complex retanning agent, and the mechanical properties of leather could be improved when the total offer percentage was controlled at 4 wt%. Moreover, the collagen fibers morphologies and lightfastness properties of leathers retanned with different retanning agents were investigated. The results showed that the total color difference ?E and the yellowness index ?b decreased significantly with the introduction of 12-GPU-550, and the leather retanned with PAA and 12-GPU-550 complex retanning agent showed the lowest value of ?E, demonstrating that the lightfastness properties were improved significantly. Therefore, it was an attractive way to combine use of PAA and 12-GPU-550 as complex retanning agent, which can improve the mechanical and lightfastness properties of vegetable tanned leathers simultaneously.