Wholly aromatic polyamic acid solution composition

Claim 1

An aromatic polyamic acid solution composition comprising: (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 at least one member selected from the group consisting of 3,3',4,4'-biphenyl tetracarboxylic dianhydride and its functional derivatives and (b) a second acid ingredient consisting of at least one member selected from the group consisting of pyromellitic dianhydride, its functional derivatives, 3,3',4,4'-benzophenone tetracarboxylic dianhydride and it functional derivatives, 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 diamine in a molar ratio of said tetracarboxylic acid component to said amine component of from 97:100 to 103:100, said amine component being selected from the group consisting of those of the formulae (I), (II) and (III). ##STR2## wherein R 1 , R 2 and R 3 respectively represent, independent from each other, a member selected from the group consisting of a hydrogen atom, alkyl radicals having 1 to 5 carbon atoms, carboxyl radical, and alkoxyl radicals having 1 to 5 carbon atoms, and A represents a divalent radical selected from the group consisting of those of the formulae: --O--, --S--, --CO--, --SO 2 --, --SO--, and --CH 2 -- and which polyamic 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° C., and dissolved in a concentration of from 5% to 40% by weight in (2) at least one organic polar solvent having a boiling point of 300° C. or less under atmospheric pressure.