Bio-based interior UV-curable coating designed for wood substrates

The advancement of UV-curable coatings derived from renewable resources is of paramount importance in achieving sustainability goals for safeguarding the environment. This study aims to synthesize novel UV-curable reactive diluent by reacting bio-based adipic acid with diethanolamine, followed by functionalizing it with glycidyl methacrylate. UV-curable bio-based oligomer was prepared by a ring-opening reaction of epoxidized castor oil with acrylic acid. The chemical structures of the resulting reactive diluent and oligomer were confirmed using analytical techniques such as end-group analysis, FTIR, and 1H NMR. A series of bio-based UV-curable formulations were prepared by combining synthesized reactive diluent with the oligomer and applied on wooden substrates. The effect of incorporating different concentrations of synthesized reactive diluent ranging from 10 to 40 wt.% on the viscosity of the synthesized oligomers was investigated by studying their rheological behavior. The UV-cured coatings were further evaluated for their extent of curing, bio-content, acid, alkali, and boiling water resistance. Thermal properties of films were further characterized for TGA and DSC. Cured coating with 40 wt.% reactive diluent exhibited 86 gloss at 60°, 5H hardness, 5B adhesion, 81.27 °C glass transition temperature, and maximum thermal decomposition temperature of 454 °C. The cured coatings have shown impressive stain resistance properties.