(JP9000896-A)      A F-contg. polyimide gas sepn. membrane of at least 0.5m2 comprises a sponge-like layer of solvent-sol. F-contg. polyimide resin and a skin layer on it. The average thickness of the skin layer is 1-100 nm, the permeability of the membrane for CO2 gas is 0.01-50 Nm3/m2/h/atm., and the sepn. factor for CO2/methane is 2-60.    Also claimed is a method of mfg. the membrane by dissolving the resin in a solvent selected from two solns., one of which (A) is an organic solvent having a dielectric constant of at most 30 and a dipole moment of at most 3.0D, and the other (B) is an organic solvent having at least one ether bonding in the molecular unit; and dipping the resin in a solvent (C) which dissolves either (A) or (B) but does not dissolve the resin for desolvation.    USE -   The membrane is used to separate components from a mixt. of gases for industrial use. Components include, e.g., hydrogen, methane, carbon dioxide, oxygen, nitrogen and water vapour.    ADVANTAGE -   The membrane is pinhole-free, uniform over a large area, and has a high permeability and a high sepn. factor . The method of mfr. is cost effective.    (JP9000897-A)      A F-contg. polyimide gas sepn. membrane of at least 0.5m2 comprises a sponge-like layer of solvent-sol. F-contg. polyimide resin and a skin layer on it. The average thickness of the skin layer is 1-100 nm, the permeability of the membrane for CO2 gas is 0.01-50 Nm3/m2/h/atm., and the sepn. factor for CO2/methane is 2-60.    Also claimed is a method of mfg. the membrane by dissolving the resin in a solvent selected from two solns., one of which (A) is an organic solvent having a dielectric constant of at most 30 and a dipole moment of at most 3.0D, and the other (B) is an organic solvent having at least one ether bonding in the molecular unit; and dipping the resin in a solvent (C) which dissolves either (A) or (B) but does not dissolve the resin for desolvation.    USE -   The membrane is used to separate components from a mixt. of gases for industrial use. Components include, e.g., hydrogen, methane, carbon dioxide, oxygen, nitrogen and water vapour.    ADVANTAGE -   The membrane is pinhole-free, uniform over a large area, and has a high permeability and a high sepn. factor . The method of mfr. is cost effective.    (JP9000898-A)      A F-contg. polyimide gas sepn. membrane of at least 0.5m2 comprises a sponge-like layer of solvent-sol. F-contg. polyimide resin and a skin layer on it. The average thickness of the skin layer is 1-100 nm, the permeability of the membrane for CO2 gas is 0.01-50 Nm3/m2/h/atm., and the sepn. factor for CO2/methane is 2-60.    Also claimed is a method of mfg. the membrane by dissolving the resin in a solvent selected from two solns., one of which (A) is an organic solvent having a dielectric constant of at most 30 and a dipole moment of at most 3.0D, and the other (B) is an organic solvent having at least one ether bonding in the molecular unit; and dipping the resin in a solvent (C) which dissolves either (A) or (B) but does not dissolve the resin for desolvation.    USE -   The membrane is used to separate components from a mixt. of gases for industrial use. Components include, e.g., hydrogen, methane, carbon dioxide, oxygen, nitrogen and water vapour.    ADVANTAGE -   The membrane is pinhole-free, uniform over a large area, and has a high permeability and a high sepn. factor . The method of mfr. is cost effective.    (US5817165-A)      A F-contg. polyimide gas sepn. membrane of at least 0.5m2 comprises a sponge-like layer of solvent-sol. F-contg. polyimide resin and a skin layer on it. The average thickness of the skin layer is 1-100 nm, the permeability of the membrane for CO2 gas is 0.01-50 Nm3/m2/h/atm., and the sepn. factor for CO2/methane is 2-60.    Also claimed is a method of mfg. the membrane by dissolving the resin in a solvent selected from two solns., one of which (A) is an organic solvent having a dielectric constant of at most 30 and a dipole moment of at most 3.0D, and the other (B) is an organic solvent having at least one ether bonding in the molecular unit; and dipping the resin in a solvent (C) which dissolves either (A) or (B) but does not dissolve the resin for desolvation.    USE -   The membrane is used to separate components from a mixt. of gases for industrial use. Components include, e.g., hydrogen, methane, carbon dioxide, oxygen, nitrogen and water vapour.    ADVANTAGE -   The membrane is pinhole-free, uniform over a large area, and has a high permeability and a high sepn. factor . The method of mfr. is cost effective.