Green Chemistry Approach for the Synthesis of Water-Soluble Alkyd Resins

The growing demand for environmentally sustainable coating materials has accelerated the development of waterborne resins derived from renewable resources. In the present study, a water-soluble alkyd resin was synthesized using rice bran oil, a renewable and non-edible vegetable oil, as the primary raw material. Initially, rice bran oil fatty acids were prepared through the saponification of rice bran oil followed by acidification. The synthesized fatty acids were subsequently reacted with glycerol via alcoholysis to form monoglycerides, which were further condensed with phthalic anhydride through polyesterification to obtain alkyd resin. Trimellitic anhydride was then incorporated to introduce additional carboxyl functional groups, enabling neutralization and water solubility of the resin. The synthesized water-soluble alkyd resin was characterized by evaluating its physicochemical properties, including acid value, viscosity, non-volatile content, and water dilutability. Coating formulations prepared from the resin were applied on mild steel substrates and assessed for film properties such as drying time, adhesion, hardness, flexibility, impact resistance, gloss, chemical resistance, and corrosion protection. The developed resin is expected to exhibit excellent film-forming characteristics with significantly reduced volatile organic compound (VOC) emissions, making it a promising eco-friendly alternative to conventional solvent-borne alkyd coatings. The study demonstrates the potential of rice bran oil as a sustainable feedstock for the development of high-performance waterborne coating resins suitable for industrial and protective coating applications.