Development of palm oil-based alkyds as UV curable coatings

Purpose - The purpose of this paper is to develop palm oil-based alkyds as ultraviolet (UV) curable coatings and investigate the parameters that affect the coating performances. Design/methodology/approach - Alkyds were formulated from palm stearin, glycerol, phthalic anhydride and maleic acid. Keeping the total molar amount of dicarbontlic acids constant, the proportions of maleic acid and phthalic anhydride were varied in order to produce polymer chains with different content of unsaturation, which is crucial for UV curability. Characterisations were carried out by FTIR and 1 HNMR. The alkyds were then mixed with methyl methacrylate (MMA) monomer as active diluents and cured by exposure to UV light. Performances of the cured coatings were tested in terms of film hardness, adhesion, water and alkali resistance, and thermal stability. Findings - Upon introducing sufficient C=C, the alkyd in combination with MMA is able to UV-cure within short time and produce film of satisfactory quality. There are several other factors, which influence the coating properties; these include thickness of coating, ratio of alkyd to active diluents, and duration of UV exposure. Social implications - The product is a form of green technology that could benefit the environment as it involves very low or near zero emission of volatile organic compounds (VOC). Originality/value - The novelty of this work lies in the formulation of new products from palm stearin, leading to new developments in the surface coating and palm oil industries.