| 摘要 |
An aromatic polyamic acid solution composition useful as an electrically insulating varnish, comprises (1) an aromatic polyamic acid which is a polymerization product of (A) a tetracarboxylic acid component containing at least 80 molar % of the sum of (a) a first acid ingredient consisting of 3,3',4,4'-biphenyltetracarboxylic dianhydride and (b) a second acid ingredient consisting of at least one member selected from the group consisting of pyromellitic dianhydride, and 3,3'4,4'-benzophenone tetracarboxylic dianhydride, the molar ratio of the first acid ingredient to the second acid ingredient being in the range of from 30:70 to 75:25, with (B) an amine component consisting of at least one aromatic amine in a molar ratio of the tetracarboxylic acid component to the amine component of from 97:100 to 103:100, and which polymeric acid has a logarithmic viscosity number of from 0.1 to 1.5 determined in a concentration of 0.5 g/100 ml in N-methyl-2-pyrrolidone at a temperature of 30 DEG C., and dissolved in a concentration of from 5% to 40% by weight in (2) an organic polar solvent.
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