Epoxy resin Cross-linked binders in aqueous finishing

Nowadays, the leather industry needs to produce a very wide range of finished articles with different levels of performance to increase their competitiveness while minimizing their environmental impact. To reduce the negative effects on the environment a strong shift from solvent to water-based recipes has taken place in leather finishing. However, most of the water-based high-performance articles require the addition of a cross-linker 1-5 to improve wet-fastness properties. The aim of the present work is to study the cross-linking reaction between an epoxy cross-linker and both acrylic binders and polyurethanes. A comparison of results shows that epoxy resin improves wet rub fastness significantly. The cross-linking reaction evolves with time within 31 days storage. Moreover, different amounts of epoxy resin are required to obtain optimum values depending on the type of leather used and on the physical characteristics of the binders employed.