| 摘要 |
PURPOSE: To improve the dehydration separation effect on gaseous hydrocarbon mixtures or the like by forming a gas separation membrane of 0.05×10<-6> to 20×10<-6> m thickness comprising an aromatic polyimide or copolyimide having a specified recurrent unit structure. CONSTITUTION: A film having 0.05×10<-6> to 20×10<-6> m thickness is formed by using at least one aromatic polyimide or copolyimide by >=90 mol.% corresponding to the recurrent unit expressed by formula I to prepare a gas separation membrane. In formula I, A represents quadrivalent aromatic groups expressed by formula II by >=50 mol.% and B is a bivalent aromatic group or a mixture of bivalent aromatic groups. The aromatic polyimide or copolyimide above described is obtd. by the reaction of an aromatic polyimide or copolyimide with an isocyanate, an epoxide or the like. The obtd. gas separation membrane can be effectively used to dehydrate, to remove acid, to separate hydrogen of gaseous hydrocarbon mixtures.
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