▎ 摘　　要

NOVELTY - The membrane (10) has an isolation functional layer (1) containing a graphene oxide, an ionic liquid having hydrophilic property and a polymer. The ionic liquid is comprised of an imidazolium ion and tetrafluoroborate. The content of the ionic liquid in the separation function layer is specific value of weight in percentage or more. The polymer is compatible with each of the graphene oxide and the ionic liquid. A porous support main portion is adapted for supporting the separation function layer. An intermediate layer (2) is arranged between the separating function layer and the porous support (3). The coating liquid is applied to a base material in order to manufacture a separation membrane. USE - Separation membrane for separating acidic gas from mixed gas. ADVANTAGE - The high separation from gas mixture is achieved. The acidic gas is separated efficiently and the operation cost is reduced. The separation performance of separation membrane with respect to mixed gas containing an acidic gas is improved. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) the method for producing separation membrane; and (2) a coating fluid for producing separation membrane. DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of a structure of a separation membrane. Isolation functional layer (1) Intermediate layer (2) Porous substrate (3) Separation membrane (10) Main surface (11,12)