| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for stably producing polyimides having an extremely high degree of polymerization and containing an aliphatic diamine as the diamine component. SOLUTION: In the process for producing polyimides by heating an aromatic tetracarboxylic dianhydride and an aliphatic diamine in the presence of a catalyst in a solvent to effect addition condensation, the first reaction process which accompanies a temperature rise by initial exothermic heat is carried out by using crotonic acid as the catalyst, and subsequently the second reaction process to heat at a temperature of not lower than the temperature reached by the initial exothermic heat is carried out.
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