Aqueous finishing with polyisocyanate cross-linked binders

Abstract

Due to increasingly stringent environmental legislation the leather industry has to produce eco-friendly articles. At the same time, it needs to manufacture fashionable and high-quality articles in order to increase competitiveness. As part of this, factories have to replace solvent-based products by water-based products in their finishing formualtions to reduce the level of volatile organic compounds. The addition of a cross-linker is required in most cases in order to obtain high performance aqueous finishes. The aim of the present work is to explore the cross-linking reaction between polyisocyanate and both acrylic binders and polyurethanes. A comparison of results shows that polyisocyanate presents a very fast reticulation [cross-linking] speed at room temperature and has a pot-life of only 4 hours. In order to obtain optimum fastness values, different amounts of polyisocyanate are required, the amounts depend on the type of leather used and on the physical characteristics of the binders employed.