Preparation and properties of UV curable rosin-based polyurethane coatings

Ultraviolet (UV)-curable coatings were prepared using rosin-based polyurethane as an oligomer with different active diluents and cross-linking monomers. The effects of the levels of different components on the properties of the polyurethane coatings were investigated, and the effects of the mass ratios of active diluents, cross-linking monomers, adhesion-promoting monomers and photoinitiators and curing times on the polyurethane coatings are discussed. The results showed that when hydroxypropyl acrylate was used as an end-capping agent, 40% methyl methacrylate as a reactive diluent, 10% dimethylolpropane tetracrylate as a cross-linking monomer, 7% hydroxyethyl diacrylate phosphate as an adhesion promoter, 4% 1173 as a photoinitiator and a curing time of 120 s, the UV-curable resin exhibited the best coating properties: a pendulum hardness of 0.63, a 60° gloss of 153.9, grade 2 adhesion, an impact strength of 500 J/m 2 and water resistance exceeding 30 days.