Synthesis and characterization of hyperbranched silane-modified alkyd as a polymer for environmentally friendly low VOC polyurethane coatings

Abstract

Purpose The purpose of this paper is to introduce a new method for modification of alkyd resin by using 3-triethoxysilylpropyl succinic acid anhydride (TESP-SA) as the core material for low volatile organic components (VOCs) polyurethane coating applications. Design/methodology/approach The structural, physical, thermal and film properties of the silane-modified (SM) alkyd were evaluated and compared with those of a silane-free alkyd resin that was prepared by a single-step method. The synthesis reaction was described in a detailed scheme and evidenced by ATR-FTIR measurements and 13C-NMR spectroscopy. Findings SM alkyd has synthesized with high solid content (85%) and low viscosity (5700 cP). As a result, environmentally friendly coatings with lower (VOC) emission are possible by using this type of alkyd polymer. The results showed that the presence of the Si atom in the final structure improved the thermal stability against the higher levels of aromatic rings in the silane-free alkyd. It was found that coatings based on SM alkyd have lower values of yellowing factor (Δa) and an increase of gloss retention percentage at different intervals of exposure to the quick ultraviolet weathering conditions. Practical implications The synthesized SM alkyd resin provided a practical solution to obtain environmentally friendly coatings with low VOC content, in addition to its improvement in alkyds’ overall characteristics, while still using natural resources – fatty acids – instead of totally petroleum resources. Originality/value TESP-SA has not been used before in alkyd polymer modifications, and this study can help countries that are interested in using environmentally-friendly coatings.