| 摘要 |
PURPOSE:To produce in good efficiency the titled polyester resin which has a low glass transition temperature and forms a film of a high heat softening temperature, by reacting specified two polyester resin with each other. CONSTITUTION:A high polymer of an intrinsic viscosity >=0.5, obtained by esterifying and/or transesterifying an aromatic polycarboxylic acid (lower alkyl ester) with an aliphatic diol and polycondensing the product in a vacuum, is depolymerized with an aromatic polycarboxylic acid to obtain a polyester resin (A) having an average degree of polymerization of 5-20 and terminated mainly with carboxyl groups. Component A is reacted with a polyester resin (B) of the formula (wherein n<=7 and R is H or a 1-3C alkyl) in such an amount that the proportion of the bisphenol A component in the obtained polyester resin for powder coating is 10-60mol% based on the total glycol component at 250-320 deg.C in a vacuum of 5Torr.
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