Preparation of oh-containing copolymer and its use as high-solid coating material

PURPOSE: To obtain an OH-contg. copolymer which has low soln. viscosity and narrow mol.wt. distribution, comprises a specified glycidyl ester and a specified unsatd. copolymerizable monomer, has, in the form of a coating material, shortened dust-free drying time and semi-cure time and excellent coating film hardness, and is useful for a coating material. CONSTITUTION: This copolymer comprises: (A) a glycidyl ester of a satd. aliph. monocarboxylic acid having a tertiary or quaternary α carbon atom, e.g. a glycidyl ester of an α-alkyl-alkanemonocarboxylic acid; and (B) at least two unsatd. copolymerizable monomers at least one of which has carboxyl group(s), wherein the copolymer has a low soln. viscosity and an unimodal narrow mol.wt. distribution. Pref., the copolymer has an OH value of 50 to 250 mgKOH/g, a soln. viscosity (concn. 50%, 25°C) of 15 to 2000 mPa.s, a wt. average mol.wt. of not more than 8600 g/mol, and a mol.wt. distribution (wt. average mol.wt./no. average mol.wt.) of not more than 3.4. COPYRIGHT: (C)1995,JPO