Epoxy Acrylate UV/PU Dual-Cured Wood Coatings

摘要

For improving the finishing performances of complicated three-dimensional coated wood products (e.g., furniture) with some shadow zones in the absence of ultraviolet (UV) light, resulting in incomplete curing of UV coatings, the aim of this study was to investigate the characteristics and effects of curing process on the properties of epoxy acrylate UV/PU dual-cured resin for wood coatings when compared with traditional UV and polyurethane (PU) coatings. The epoxy acrylate oligomer was synthesized for providing a double bond of acryloyl group and a secondary hydroxyl group. The UV/PU dual-cured coating was formulated with epoxy acrylate resin/tripropylene glycol diacrylate (TPGDA) monomer by the weight ratio of 80/20, 3% dosage of benzil dimethyl ketal as a photoinitiator, and the NCO/OH mole ratio of 1.0. The aromatic polymeric diphenylmethane diisocyanate was used as a hardener. The films of the dual-cured coating, obtained from UV-cured or room temperature-cured process, showed an excellent tensile strength, elongation at break, impact resistance, and lightfastness when compared with traditional UV and PU coatings; especially, the adhesion of UV/PU dual-cured coating by UV-cured process was better than that of traditional UV coating. It can therefore be concluded that the epoxy acrylate oligomer-based dual-cured coating could readily be used for complicated wood products finishing.