| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject fine powder in good productivity without mechanically pulverizing by polymerizing a lower alcohol half esterification product of an aromatic tetracarboxylic dianhydride with an aromatic diamine in a solvent. SOLUTION: (A) A lower alcohol half esterification product of an aromatic tetracarboxylic dianhydride is polymerized with (B) an aromatic diamine in (95:100) to (100:95) molar ratio of the component A/the component B in (C) a solvent (e.g. N-methyl-2-pyrrolidone) at a solid content concentration of preferably 20-60 wt.%, more preferably 30-40 wt.% to provide the objective powder. The component A is obtained by subjecting (i) an aromatic tetracarboxylic dianhydride (e.g. 3,3',4,4'-biphenyltetracarboxylic dianhydride) to half esterification with (ii) a lower alcohol, preferably a 1-5C aliphatic alcohol (e.g. methanol) in an amount of 2-3 mol based on 1 mol component (i).
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