Photopolymerization process of UV powders. Characterization of coating properties

The aim of the study was to correlate the characteristics of UV powder resins with the photochemical process and the final coating properties. RT-FTIR spectroscopy equipped with an environmental cell was implemented to follow photopolymerization reactions of UV powder systems under temperature control. The influence of additional acrylate monomers into UV powders was assessed and linked to the properties of the final coatings. An increase in concentration of reactive functions was found to lead to higher reactivity, even for relatively low working temperature. Glass transition temperature, crosslinking density and resistance towards scratch and solvent have been investigated and were found to be significantly improved, even for systems exhibiting a non negligible amount of unreacted groups after the curing step. These results highlight the interest of such coatings for heat-sensitive substrates like wood based panels largely used in the furniture market.

► The reactivity of UV powders was studied by RT-FTIR under temperature control within an environmental cell.
► The impact of the curing temperature on the photopolymerization process was pointed out.
► The effect of the addition of multifunctional acrylate monomers into UV powders was assessed.
► The properties of final UV powder coatings were determined by DMA, scratch and solvent tests.