| 摘要 |
PURPOSE:To obtain a dope capable of giving films free from large protuberances thereon, by filtering a low-viscosity polymer solution prepared by polymerization between an excess of aromatic diamine and aromatic tetracarboxylic acid followed by addition of said carboxylic acid again to processed with polymerization. CONSTITUTION:An excess of aromatic diamine component and aromatic tetra- carboxylic acid component are polymerized in an organic polar solvent to prepare a low-viscosity polymer solution with a viscosity <=100 poises (pref. <=60 poises) at 30 deg.C. The resulting polymer solution is then filtered to remove coarse particles (foreign substances with a particle size >=1mum) followed by addition to the filtered solution an equivalent amount of the aromatic tetracarboxylic acid to that of the aromatic diamine component intact to processed with the polymerization, thus obtaining the objective dope. The excessive amount of the aromatic diamine present in the organic solvent is so regulated as to correspond to 5-50 (pref. 10-40)wt% of the whole aromatic diamine.
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