| abstract |
PURPOSE: To obtain the titled porous film for separating gases and solutions, having improved permeability, by forming a film from a dope prepared by dissolving a polyamic acid in a mixture solution of a solvent capable of dissolving the polymer with a solvent incapable of dissolving the polymer, and drying the formed film under heating. n CONSTITUTION: (A) An aromatic polyamic acid obtained by polymerizing an aromatic tetracarboxylic acid component with an aromatic diamine component is uniformly dissolved in a mixture solution of (i) 100pts.wt. organic polar solvent, e.g. N,N-diemthylformamide, capable of dissolving the polyamic acid (A) in a concentration ≥5wt% with (ii) 5W150wt% organic polar solvent, e.g. phenanthrene, incapable of dissolving the polyamic acid (ii) in a concentration ≥3wt%, and having a lower evaporation rate than the solvent (i) to give a polymeric concentration of about 3W30wt%, and the resultant dope is formed into a thin film at 0W120°C. The resultant film is then dried at about 30W400°C to remove the respective solvents slowly, imidize the polyamic acid (A) and give the aimed porous polyimide film. n COPYRIGHT: (C)1982,JPO&Japio |