Photo‐induced catalytic poly‐trimerization of polyisocyanurates

Abstract

Radiation curing is an excellent option for the economical implementation of coatings while simultaneously producing technically advanced products. Nevertheless, the number of materials used is mainly limited to pure (meth)acrylate and epoxy systems. Polyisocyanurates could be an excellent addition to this range, especially due to their thermal and chemical stability. In this work, through the use of a transition metal-based photocatalyst, as well as the use of 1,5-diazabicyclo(4.3.0)non-5-en as a co-catalyst, formulations are presented, which enable pure polyisocyanurates to be used in radiation-based coating technology. Trimerization with this system using any primary isocyanates worked and consequently thus opened the possibility for aromatic and aliphatic polyisocyanurates. Using monofunctional isocyanates, the theoretical background of trimerization as well as the theoretical enthalpy is evaluated and the possibilities as well as the limitations for poly-trimerization of polyisocyanurates are analyzed. Finally, photo-induced catalytic poly-trimerization of aliphatic isocyanates is used to obtain samples with a Tg in the range of 100 °C and onset of degradation above 400 °C. Thus, for the first time, a framework for the use of isocyanates in the field of photopolymerization and, in particular, in the field of radiation-based coating of polyisocyanurates is provided for further development.