Synthesis and evaluation of non-isocyanate polyurethane polyols for heat-cured thermoset coatings

A series of novel polyurethane polyols was successfully synthesized using cyclic carbonate/polyamine chemistry. By harnessing the potential of this environmentally friendly synthetic route, non-isocyanate polyurethane polyols with varying hydroxyl content and molecular weights were prepared for thermosetting coating applications. Fourier Transform Infrared (FTIR) and Proton Nuclear Magnetic Resonance (H NMR) spectroscopy confirmed the formation of expected functional groups. By curing with an amino resin crosslinker in varying amounts, coatings with significantly different mechanical properties-from highly flexible to very hard- were obtained. The study showed that coatings designed with higher urethane content in the backbone show improved adhesion to the substrate. Results also revealed that the flexibility of the backbone structure of the polyol and the amount of crosslinker used have a significant influence on the flexibility, impact resistance, and chemical resistance of cured thermoset coatings.