Process for preparing liquid coating compositions curable with electron beams

Contrary to conventional liquid coating compositions prepared from glycidyl methacrylate copolymers, the liquid coating composition herein provided cure completely even in the presence of air to give a coating film free from tackiness. The composition is prepared by esterifying a mixture of an epoxidized drying or semidrying oil (20 to 80 parts) and a glycidyl methacrylate copolymer containing 5 to 30% glycidyl methacrylate unit (80 to 20 parts) with an α, β-unsaturated monocarboxylic acid until at least 50% of the original epoxy group has been esterified. Completely cures upon irradiation with a low dose of electron beams (1 to 9 Mrad) and is useful for coating wood, metals, resins and glass. In one example (grams), an epoxidized linseed oil (33) was reacted with a mixture of glycidyl methacrylate (15), Me methacrylate (15) and Et acrylate (70), and then with a mixture of acrylic acid (14) and dimethylaminoethyl methacrylate (6.7) until an acid value of 11 was attained. The product was diluted with Me methacrylate to give a solution of 50% concentration, to which was added titanium white to give a white enamel. A soft steel sheet was coated with the latter and irradiated with electron beams. The cured coating film had an excellent luster and high resistance to impact and xylene. (Kaichi, S.)