Tailor-made Crosslinkers for High Performance PUR Coatings - Hyperbranched Polyisocyanates

摘要

The introduction of Self-Crosslinking Isocyanates (SCI) as AB_2-building blocks makes it possible to synthesize hydroxyl- or isocyanate-group terminated dendrimers. Furthermore, inherent reactivity differences of non equivalent NCO-groups of specific diisocyanates (such as isophorone diisocyanate [IPDI] or toluylene diisocyanate [TDI]) can be used to build up hyperbranched polyurethane structures in a one pot synthesis without the need of arduous protection/deprotection steps. This synthetic approach allows the construction of tailor-made hyperbranched molecular architectures which are end-functionalized with either hydroxyl or isocyanate groups. These products were then tested as crosslinkers in 2-component coating formulations where they displayed better hardness than any other aliphatic isocyanate raw material.