Daniel Rogez

A new innovative stabilization method for the protection of natural wood

Abstract The UV-light exposure of natural wood leads initially to a fast color change, and in the further stages to large chemical modifications and mechanical breakdown of the wood surface layer. Even in diffuse light exposure, prevailing in indoor conditions, the discoloration of wood is a serious esthetical drawback, for example, for furniture and parquetry. Progress has been made with the development of new stabilizers, which offer a significant benefit compared to the currently used benzotriazole UV-absorbers. Using these new stabilizers the wood photo-protection against discoloration and the durability of clear and transparent pigmented coating systems can be significantly improved.

Organic vs inorganic light stabilizers for waterborne clear coats: a fair comparison

As a consequence of regulatory pressure to reduce solvent emissions, there is high growth rate of “compliant technologies” such as waterborne (WB) coatings. However, a change from conventional solventborne (SB) to WB technologies should not compromise the protective function of the coatings and the used raw materials. The use of light stabilizers, such as UV absorbers (UVA) and hindered amine light stabilizers (HALS) are state-of-the-art and largely improve the coating durability and service lifetime. Today in the case of UVA one has to differentiate between inorganic and organic products: the most widely used organic UVA for coating applications are 2-(2-hydroxyphenyl)-benzotriazole (BTZ) and 2-hydroxyphenyl-s-triazine (HPT) derivatives. Inorganic products are ideally nano particulate materials—so-called mineral screeners (MS)—comprised of titanium dioxide (TiO2), zinc oxide (ZnO), or cerium oxide (CeO2). The challenge here is to convert existing products which are in general hydrophobic substances into product forms that enable easy incorporation and unproblematic dispersion into WB systems. This article describes UV absorbers which are commercially available for waterborne coatings. Different classes are tested with regard to their protective function in joinery coatings as well as with regard to their influence on coatings color and transparency. The findings of this study showed clearly that the 2-hydroxyphenyl-s-triazine class outperforms all other UVA in terms of long-term performance without influencing initial coating properties.