| 摘要 |
PROBLEM TO BE SOLVED: To provide a resin composition for coating improved in electrodeposition coating properties and in coated surface smoothness, having a low organic solvent content and free from a lead compound by compounding a specific modified epoxy-polyamine resin, SOLUTION: A diepoxide compound selected from formulae I and II and a bisphenol A type epoxy resin having an epoxy equivalent of 170-500 are reacted with bisphenols to give an epoxy resin having a number average mol.wt. of 800-10,000. This epoxy resin is reacted with a cyclic ester of formula III in the presence of a catalyst at 120-200 deg.C to give a lactone-modified epoxy resin, which is reacted with a reactive hydrogen-containing amine compound in an organic solvent at 30-150 deg.C for 1-5 hr to give a modified epoxy-polyamine resin having a number average mol.wt. of 1,000-20,000 and an amine number of 15-100, which is incorporated into the resin composition. In the formula, R1 is H or a 1-6C alkyl; m and n are each an integer not less than 0; m+n:1-20; X is 1-9; y is 1-50; R2 is H or methyl; and p is 3-6.
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