Boreal forest conifer extracts: potential natural additives for acrylic polyurethane coatings for the protection of heat-treated jack pine

Abstract

Among consumers, heat-treated wood recently gained more importance due its attractive darker color along with several other advantages such as improved biological resistance, dimensional stability, and thermal insulating properties. However, exposure to the exterior environment drastically changes the attractive darker color of this product. From dark brown, it becomes almost white. For this reason, development of a nontoxic transparent coating which can protect the heat-treated wood from photodegradation is very important. Addition of UV stabilizers (UV absorbers, HALS, antioxidant) is necessary for transparent coatings in order to filter the harmful UV/VIS radiation. In this present study, the effectiveness of natural antioxidants, extracted from conifer barks or needles from trees in protecting the color of wood, as additives to acrylic polyurethane coating is examined. Also, their UV/VIS absorption capacities and semi-quantitative component analyses have been presented. The toxicity of these new products was also evaluated on human normal skin cells due to ever increasing environmental legislation. The chemical modification of acrylic polyurethane coating containing conifer bark and needle extract were examined by ATR–FTIR analysis. Promising results were obtained for these natural antioxidants which showed very high UV absorption characteristics and antioxidant activity.