| 摘要 |
PROBLEM TO BE SOLVED: To obtain a crystalline polyimide excellent in heat stability in the molten state by subjecting a specific diamine monomer to catalytic reduction while 1,3-bis(4-nitrophenoxy)benzene is being charged into a reactor into which a solvent and a catalyst are charged and hydrogen is introduced in advance in a process for producing a copolymer having a specified structure from specific monomers and a specific terminal blocking agent. SOLUTION: Diamines of formulas V and VI and a tetracarboxylic dianhydride of formula VII are used as the monomers; and a monoamine of formula VIII and/or a dicarboxylic anhydride of formula IX is used as the terminal blocking agent. A diamine of formula V, i.e., 1,3-bis(4-aminophenoxy) benzene, is subjected to catalytic reduction while 1,3-bis(4-nitrophenoxy)benzene is being added into a reactor into which a reaction solvent and a catalyst are charged and hydrogen is introduced in advance. The resultant polymer has a main chain comprising repeating units of formulas I and II and molecular terminals each comprising a group of formula III or IV.
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