| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject powder suitable for producing a polyimide shaped product, excellent in stability and capable of being converted into a thermoplastic polyimide having a high polymerization degree by reacting a specific aromatic diamine with an aromatic tetracarboxylic acid. SOLUTION: This wholly aromatic polyimide precursor powder comprises a salt produced from an aromatic diamine of formula I or II and an aromatic tetracarboxylic acid of formula III. The powder is obtained by mixing the compound of formula I or II with the compound of formula III in a poor solvent (preferably methyl alcohol, acetone, dioxane) for the polyimide precursor to be produced, and subsequently isolating the powder from the obtained suspension in which the powder is dispersed. When the powder is produced, an aromatic derivative having two carboxyl groups or an aromatic derivative having an amino group is preferably added in the same molar number as that of an excessive amine component or acid component as a terminal-sealing agent. The terminal-sealing agent includes terephthalic acid andβ-aminonaphthalene.
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