Electron-curable coating composition

An electron-curable, acryl-modified, epoxy coating composition having a high electron-curability and well balanced film properties is provided. It is prepared by reacting an acidic unsaturated polyester (A) which an epoxy resin (B) and an α,β-olefine acid (C) and dissolving the resulting product into a vinyl monomer (D). Preferably, (A) contains, in its molecule, the ethylenic units not at random but block-wise which is useful in obtaining a higher electron-curability and a higher impact strength of film. In one example, 1.0 mole of propylene glycol was reacted with 0.5 mole of fumaric acid and the product was reacted with 0.7 mole of phthalic anhydride to give (A). 1 mole of (A) was reacted with 0.3 mole of Epikote 1004, 0.5 mole of Epikote 1001, 0.4 mole of Epikote 828 and 0.3 mole of Epikote 872. The product was reacted with 3.0 moles of methacrylic acid to give an acryl-modified epoxy resin. The latter was dissolved into a mixture of styrene, ethyl acrylate and methyl methacrylate (0.3:0.2:0.5 by wt.). A ground steel board was coated with the resulting composition and irradiated with electron beams (total dose 4 Mrad, conveyer speed 3.4 m/min.). Properties of the cured film were as follows: impact strength, good; resistances to solvents, good; pencil hardness, 2H; Erichsen test, 8 mm; tensile strength 7.7 kg/mm2; elongation 7.8%. (Kaichi, S.)