PRODUCTION OF ASYMMETRICAL MEMBRANE FOR SEPARATION OF GAS

PURPOSE:To efficiently densign the conditions for forming a gas separation asymmetrical membrane showing the separation performance as the characteristics of a raw material, and to obtain the separation coefft. for methane and carbon dioxide which is expected for characteristics of the raw material of the membrane when the gas separation asymmetrical membrane is formed iN these conditions determined by this method. CONSTITUTION:A film forming liquid is applied on a supporting body into uniform thickness. This film forming liquid essentially consists of polyethersulfone (PES) or polysulfone (PS) as the film material and an intrinsic solvent which dissolves the film material, and an auxiliary solvent may be added as necessary. The surface layer of the applied film forming liquid is partly vaporized and dipped in a gelling agent to cause phase transition to form a gel film and to produce the gas separation symmetrical membrane. In this method, the optimum conditions for forming the membrane concerning to the component and compsn. of the intrinsic solvent auxiliary solvent added as necessary, and the gelling agent are selected from the following characteristics. (1): gelation point of the film forming liquid, (2): mixing heating value of the solvents and the gelling agent, and (3): dissolving rate of the solvent to the gelation agent.