Improvement of the durability of clear coatings by grafting of UV-absorbers on to wood

The photochemical resistance of polymers can be improved greatly by using grafted photostabilisers. This method was used here to improve the photostability of wood and the performance of clear coatings on wood. Reactive UV absorbers (UVAs), including 2-hydroxy-4 (2,3-epoxypropoxy) benzophenone (HEPBP) and some epoxy-functionalised triazine-type UVAs, were synthesised and the reaction conditions required to graft UVAs on to wood were examined. Grafting of reactive UVAs was more effective than UVA treatments without grafting or than chromium trioxide modification for restricting losses in weight and tensile strength of thin wood veneers during weathering. Grafting UVAs on to wood reduced photochemical changes at exposed wood surfaces and greatly improved the performance of clear coatings on modified veneer surfaces.