| 摘要 |
PURPOSE:To obtain a polyamide-imide polymer improved in flexibility, flex resistance and film forming property, by reacting an organic isocyanate with a specified higher dibasic acid and a cyclic dicarboxylic acid anhydride. CONSTITUTION:An organic isocyanate or a masked organic isocyanate is reacted with a higher dibasic acid component based on a long-chain dibasic acid of the formula and a cyclic dicarboxylic acid anhydride. In the formula, R is an aliphatic hydrocarbon group which constitutes the skeleton of said 18C or higher long-chain dibasic acid. A particularly desirable higher dibasic acid used is a dimer acid obtained by polymerizing refined vegetable unsaturated fatty acid. As the cyclic dicarboxylic acid anhydride, trimellitic anhydride is desirable from the viewpoint of heat resistance and economy. The dimer acid is used in an amount of 0.1-20mol% based on the total weight of the dimer acid and the cyclic dicarboxylic acid anhydride.
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