Rainer Königer

Tailor-made crosslinkers for high performance PUR coatings: Hyperbranched polyisocyanates

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.

Radiation curable materials – principles and new perspectives

Increasing environmental concerns and the ensuing legislation to cut emissions of volatile organic compounds (VOCs) have been major driving forces behind the development of radiation cured coatings over the past 25 years. Today radiation cured coatings are known for their good overall performance and their excellent resistance against chemical and physical surface damages. Advanced photoinitiator systems allow the light stabilisation of UV-curable formulations and the outdoor application of the coating. The rapid curing, combined with the possibility of immediate processing of the coated objects opens the way for radiation curing – in 100%-, water based-, and dual cure systems as well as for radiation curable powder coatings – for a wide variety of application.