Wood surface preparation by silane Nano film formation using sol-gel methodto improve the adhesion of alkyd and polyurethane coatings

In this research, the effect of Silane nanofilm formation using sol-gel method on improving theadhesion of Alkyd and Polyurethane coatings to wood surface in urban furniture wasinvestigated. For this purpose, the surface of spruce wood (Picea abies L.) was modified withTetraethoxy silane (T) and glycidoxy propyl trimethoxy silane (G) sol-gel materials. Then,solvent-borne alkyd (AS), solvent-borne polyurethane (PS) and waterborne polyurethane (PW)coatings were applied. Microscopic observation by fluorescence, confocal laser scanningmicroscopy (CLSM) and SEM showed that the silica component of nanosol covered the wholewood surface homogeneously, while alkyd and polyurethane coatings were depositedpreferentially in the surface depressions. The combined analysis of ATR-FTIR, XRD and XPSdemonstrated that the surface was covered with silicon oxides (SiO2) attached to hydrocarbonchains. The results of accelerated weathering test showed that the surface modification by sol-gelimproved the weathering resistance of top coatings and reduced their roughness. The silane-basedmaterials improved the adhesion and abrasion resistance properties, and Tetraethoxy silane had abetter performance in comparison with glycidoxy-propyl trimethoxy silane. Among coatings,the highest tensile strength was observed for waterborne polyurethane. Solvent-borne alkydshowed the lowest tensile strength. Overall, the sol-gel derived hybrid inorganic–organic thinfilm was found to enhance the adhesion strength of coatings to wood surface and improve theweathering resistance of wood.

Keywords:

Coating , Sol-gel , Alkyd , Polyurethane , Nano silane