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Abstract

Provided are paint films with outstanding paint film performance traits such as water resistance and chemical resistance, etc., and outstanding finished appearance. The water-based paints are easy to apply and have outstanding storage stability. The invention further provides an acrylic graft copolymer obtained by reacting a acrylic copolymer (a) of acid number 35 to 120 mg KOH/g, hydroxyl group number 50 to 150 mg KOH/g, glass transition temperature -20 to +50.degree. C. and number average molecular weight 4500 to 9000, and a monomer combination (b) comprising an unsaturated monomer (b1) containing a glycidyl group and an unsaturated monomer (b2) containing a hydroxyl group to give an acid number of .ltoreq.15 mg KOH/g and a hydroxyl group number of 50 to 150 mg KOH/g. Copolymer (a) and monomers (b) are reacted in specified proportions in a single stage to make the claimed water-dispersible acrylic graft copolymer which has an acid number of 10 to 30 mg KOH/g, a hydroxyl group number of 50 to 150 mg KOH/g, a glass transition temperature of -20 to +50.degree. C. and a number-average molecular weight of 10,000-100,000 by grafting side chains formed from the aforementioned (b) to a main chain from the aforementioned (a), and this graft copolymer is dispersed in an aqueous medium to obtain the claimed water-based paint.

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First Claim