Synthesis of HDI/IPDI hybrid isocyanurate and its application in polyurethane coating

Abstract A solvent-free hybrid isocyanurate was prepared by trimerization of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), and characterized by gel permeation chromatography (GPC), gas chromatography (GC), nuclear magnetic resonance (NMR), and electrospray ionization mass spectrometry (ESI-MS). The results showed that HDI/IPDI hybrid isocyanurate could be prepared in the presence of 2-hydroxypropyl-trimethyl-azanium catalyst at reaction temperatures between 50 °C and 70 °C. Both the GC and 1 H NMR analyses identified the favorable linear relationship between the feed ratio of the starting monomers and the amount of each individual isocyanate incorporated into the oligomer (reaction ratio). The polyurethane coatings prepared with HDI/IPDI hybrid isocyanurates demonstrated faster drying speed, higher hardness and gloss and better distinctness-of-image (DOI) than the analogous coatings prepared with cold-blends of HDI isocyanurate and IPDI isocyanurate.