| 摘要 |
PROBLEM TO BE SOLVED: To produce the subject resin having a low elastic modulus, small in warpage and excellent in various characteristics by reacting an aromatic polyisocyanate with a carboxylic acid derivative having an acid anhydride group and a specific dicarboxylic acid mixture in a specific solvent. SOLUTION: This method for producing a modified polyamideimide preferably having a number-average mol.wt. of 4,000-30,000 comprises reacting (A) an aromatic polyisocyanate (e.g. 4,4'-diphenyldiisocyanate) with (B) a trivalent carboxylic acid derivative having an acid anhydride group (especially preferably trimellitic anhydride) and (C) a dicarboxylic acid mixture of the formula [(a) is 0-20; (b) is 0-70; (c) is 1-90; R1 , R2 are each H, a 1-3C alkyl) in a nitrogen-free polar solvent (especially preferablyγ-butyrolactone) especially at 80-200 deg.C.
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