| 摘要 |
PURPOSE:To obtain a polyamic acid having a narrow MW distribution and excellent mechanical properties, electrical insulating property, chemical resistance and film forming property, by polymerizing a tetracarboxylic acid dianhydride and a diamine in an organic solvent under irradiation with ultrasonic waves. CONSTITUTION:A tetracarboxylic acid dianhydride is polymerized with a diamine in an organic solvent under irradiation with ultrasonic waves or under both irradiation with ultrasonic waves and the action of mechanical mixing. By performing the polymerization in this way, a polyamic acid of a very narrow MW distribution <=3 (in terms of Mw/Mn) can be formed. The curing temperature is usually 500 deg.C or above, especially, in the range of 200-400 deg.C. The polymerization is preferably performed in a nonoxidizing atmosphere such as a vacuum or an inert gas.
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