PURPOSE: To obtain a long shelf life concentrated prepolymer composition used in the production of a polymide by adding a diamine and a specified end capping compound to a solution of biphenyltetracarboxylic acid in an specified solvent and removing a part of the solvent from the mixture by distillation.
CONSTITUTION: A solution of a dialkyl, trialkyl or tetraalkyl ester of biphenyltetracarboxylic acid in an ethyl acetate/methanol (1/3-1/60 molar ratio) solvent is prepared. A diamine and an end capping compound (a bifunctional compound having at least one unsaturation and forming an end capping group by reaction with a diamine or an ester) are added to the prepared solution to prepare a monomer solution, and a part of the solvent is removed from the monomer solution by distillation to produce a substantially homogeneous concentrated prepolymer composition. It is desirable that the molar ratio of the ethyl acetate in the ester solution to the methanol is about 1:3 to about 1:20.
POORU JII CHIEN
UOODO EFU RAITO
| JPH04213325A | 1992-08-04 | |||
| JPS5022091A | 1975-03-08 | |||
| JPS5721339A | 1982-02-04 |
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