Preparation and characterization of a novel ultraviolet/thermal dual-curing thiol-ene/polyurethane acrylate coating

A novel ultraviolet (UV)/thermal dual-curing thiol-ene/polyurethane acrylate (PUA) coating of PUA oligomer, tripropylene glycol diacrylate, 2,4,6-trimethylbenzoyldiphenyl phosphine oxide, and trimethylolpropane tris (3-mercaptopropionate) was prepared. The coating had a rapid surface drying rate with UV radiation (400 W, 50 W/cm 2 ). For example, the surface of the novel thiol-ene/PUA coating dried within 3 s. The hardness, gel content, and initial decomposition temperature at 5 wt% weight loss of the UV/thermal dual-cured sample after 10 min of UV irradiation, followed by heating at 150°C for 20 min, were 37 D, 90.3%, and 302.2°C, respectively, which were higher than the 30 D, 87.7% and 284.9°C of the UV curing control after 10 min of UV irradiation. The curing time of the 1-mm-thick coating was 4.5 min in indoor sunlight (2.3 ± 0.3 mW/cm 2 ) with a gel content of 83.8%. This coating could be applied in the rapid prototyping field with UV or sunlight exposure. Thermal treatment after UV curing could increase the crosslinking degree and influence the sample performance.