| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyimide excellent in hydrolysis resistance and having a low ionic impurities concentration and a method which can produce the same directly without the necessity for passing through a polyamic acid. SOLUTION: At least one first acid dianhydride is reacted with at least one first diamine in a heated polar solvent, then, at least one second acid dianhydride and at least one second diamine are added to the reaction system, and the reaction is caused to proceed. The reaction is carried out in the presence of a lactone polymerization catalyst, thus enabling the direct imidization to be realized. The resultant polyimide has a wt. average mol.wt. of 20,000-150,000 and an ionic impurities concentration of 0.1 ppm or lower.
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