Abstract: A porous film with chemical resistance of this invention includes a porous film base covered with a chemical-resistant polymeric compound and has a multiplicity of communicating micropores having an average pore size of 0.01 to 10 ?m. The chemical-resistant polymeric compound can be, for example, any of phenolic resins, urea resins, melamine resins, benzoguanamine resins, polyimide resins, epoxy resins, benzoxazine resins, polypropylene resins, polyurethane resins, fluororesins, alkyd resins, cellulose acetate resins, phthalic resins, maleic resins, and silicone resins.

Abstract: A porous film of the invention is a porous film having a large number of continuous micropores. The film has a thickness of 5 to 200 ?m, has an average surface pore size A of 0.01 to 10 ?m, an average surface porosity C, and has an average inside pore size B and an average inside porosity D. The ratio A/B of A to B is 0.3 to 3. The porous film is produced by casting a polymer solution containing a polymer onto a substrate to form a film and subjecting the film to phase conversion to thereby form a porous film. In the method, the polymer constituting the porous film has a surface tension Sa [mN/m], the substrate has a surface tension Sb [mN/m], and Sa and Sb satisfy the following condition: Sa?Sb??10.

Abstract: A porous film with chemical resistance of this invention includes a porous film base covered with a chemical-resistant polymeric compound and has a multiplicity of communicating micropores having an average pore size of 0.01 to 10 ?m. The chemical-resistant polymeric compound can be, for example, any of phenolic resins, urea resins, melamine resins, benzoguanamine resins, polyimide resins, epoxy resins, benzoxazine resins, polypropylene resins, polyurethane resins, fluororesins, alkyd resins, cellulose acetate resins, phthalic resins, maleic resins, and silicone resins.

Abstract: A method of the invention produces a porous film by casting a polymer solution containing a polymer onto a substrate to form a film, and subjecting the film to phase conversion to thereby form a porous film. In the method, the polymer constituting the porous film has a surface tension Sa [mN/m], the substrate has a surface tension Sb [mN/m], and Sa and Sb satisfy the following condition: Sa?Sb??10. This method can produce a porous film having a high rate of hole area at its surfaces and having homogenous micropores from the surfaces to the core thereof. A porous film of the invention is a porous film having a large number of continuous micropores. The film has a thickness of 5 to 200 ?m, has an average surface pore size A of 0.01 to 10 ?m and an average rate of surface hole area C and has an average inside pore size B and an average rate of inside hole area D inside thereof, in which the ratio A/B of A to B is 0.3 to 3, and the ratio C/D of C to D is 0.7 to 1.5.

Abstract: To provide a separating membrane of a polyion complex having excellent separation factor, permeation rate and performance stability and being used in separating a mixture of water and an organic substance in accordance with the separating membrane technology. The separating membrane is a novel one comprising a polyion complex which comprises an ionic combination of an anionic polymer having carboxyl groups with a cationic polymer having divalent piperidinium bases. With respect to the separation characteristics of the separating membrane, a permeation rate is at least 100 g/m.sup.2 .multidot.hr and a separation factor is at least 1,000 in an evaluation according to pervaporation (by reducing the pressure outside the hollow fiber while feeding a 99 wt. % aqueous ethanol solution inside the same at 70.degree. C.). Further, a durability evaluation shows that the permeation rate and separation factor of the separating membrane are respectively 110 g/m.sup.2 .multidot.

Abstract: A selectively water-permeable hydrolyzed membrane characterized in that it is mainly made of a material which can generate a carboxyl group by hydrolysis and that a part of the material is hydrolyzed to have carboxyl groups, which may be further coated with a hydrophilic polymer. The above membrane is useful as a selectively water-permeable membrane and is applicable not only to pervaporation and vapor permeation, but also to reverse osmosis, dehumidification of air and so on.

Abstract: A permeable membrane through which water or its vapor permeates selectively nd which contains a polyion complex formed by the association by an ionic bond between an anionic polymer and a cationic polymer on the surface of the membrane and/or in the membrane. This membrane is useful in the separation of water from an aqueous solution of an organic substance or a gaseous mixture of water with an organic substance, and exhibits excellent resistance to solvent, particularly water, and a high permeation rate and a high separation coefficient.