| 摘要 |
PROBLEM TO BE SOLVED: To provide a water-soluble polyimide precursor capable of being applied to an aromatic polyimide and hardly causing the reduction of heat resistance (especially thermal degradation temperature) and mechanical properties (especially tensile strength and elongation), and further to provide an aqueous solution of the polyimide precursor, a method for producing the aqueous solution and the polyimide. SOLUTION: This powdery water-soluble polyimide precursor is obtained by reacting a polyimide precursor comprising a tetracarboxylic acid component and an aromatic diamine component with 1,2-dimethylimidazole and/or 1-methyl-2-ethylimidazole in an amount of >=0.7 molar time as much as the carboxy group of the polyimide precursor, and separating and collecting the product from the resultant mixture. The polyimide precursor solution is obtained by dissolving the water-soluble polyimide precursor in water. The method for producing the solution of the polyimide precursor comprises dissolving the water-soluble polyimide precursor in the water. The polyimide has the heat resistance nearly the same as that of the polyimide obtained by heating and imidizing the organic solvent solution of the polyimide precursor.
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