| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject polyimide containing a specific recurring unit as a component, having good mechanical physical properties and heat resistance, and a low hygroscopic rate, and useful for a coating film, s film, etc. SOLUTION: This low hygroscopic polyimide containing a recurring unit of the formula [(n) is an integer] as a component, is preferably obtained by polymerizing a biphenyltetracarboxylic acid such as 3,3',4,4'- biphenyltetracarboxylic acid dianhydride with 4,4'-bis(4-aminophenoxy)biphenyl in an organic polar solvent (e.g.; N-methyl-2-pyrrolidone) preferably at 5-50 deg.C to obtain a polyamic acid solution, applying the polyamic acid solution containing preferably 5-50 wt.% polyamic acid on a supporting body or a substrate, heating and drying for imide formation. The polyamic acid solution has preferably 1.05-0.95 molar ratio of the tetracarboxylic acid dianhydride to the diamine. Also, it is preferable to add an imide forming catalyst to the polyamic acid solution.
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