Improvement in Weatherability of Coated Wood-Surface by Addition of TiO_2 Micro Particlate and PEGMA to Clear Paint

摘要

Improvement in weatherability of the coatd wood by an addition of a titanium oxide (TiO_2) micro particulate and polyethylene glycol mono-methacrylate (PEGMA) to clear paint was examined. The TiO_2 micro particulate was expected to decrease a light-induced degradation of wood due to the reductin of light passing through coating film, and the PEGMA was expected to decrease a dimensional change of wood caused by change of moisture content and repress the light degradation of wood due to the ability to generate peroxide. The addition of these materials did not reduce the adhesion of coating film to wood. The addition of TiO_2 micro particulate decreased greatlky the color difference of coated wood in comparison to non-addition without influence on the gloss-iness change of the coating film in an accelerated weathering test. The color difference of wood coated with the paint containing TiO_2 micro praticulate with 2PHR was smaller than 1/2 of non-added paint, though the addition did not have the effect on the improvement of defect developed in coating film in outdoor exposure test. The addition of PEGMA with 20PHR decreased the color difference by 1/2 of non-addition, and began to improve the development of defec in coating film after exposure for 250 weeks. The addition of both the TiO_2 micro praticulate the PEGMA decreased the color difference by 1/2 of non-addition and decreased the defect in coating film after exposure for 200 weeks.