Cross-linked polymers for aqueous finishing.: Binders crosslinked with polyaziridine.: Part I:: Behaviour of polyurethane

Aqueous finishing emerges as an alternative to solvent based finishes. which have to be limited due to their toxicity, negative effects on the environment and in terms of safety. It is necessary, in order to be able to introduce aqueous systems progressively, to use cross-linkers that react with polymers. Otherwise, it is not possible to obtain the physical properties required for most leather goods. The present study aims to look into the behaviour of polyurethane binders cross-linked with polyaziridine: the amount of cross-linker used, the type of polymer employed, the type of tannage and retannage effected and the evolution of the reaction over time. A comparison of results shows that the type of tannage and retannage, as well as the physical characteristics of the polyurethane used are influential factors in the behaviour of polyurethane binders cross-linked with polyaziridine. Different amounts of polyaziridine are needed with regard to the type of tannage and retannage effected and to the physical characteristics of the polyurethane used.