| 摘要 |
PURPOSE:To prepare a membrane excellent in the ratio of the permeation speed of hydrogen and carbon monoxide, in preparing the membrane, by adding a specific aliphatic carboxylic acid compound to a dope consisting of polyimide and a phenolic compound. CONSTITUTION:A polymer used as a membrane comprises aromatic polyimide having 90% or more of a repeating unit represented by Formula in its main chain. This polyimide is dissolved in a phenolic solvent, especially, a halogenated phenolic compound with a b.p. of 300 deg.C or less to prepare a dope. Aliphatic carboxylic acid such as butyric acid, valerianic acid, vinyl acetate or adipic acid is added to said dope in an amount of 5-40wt% of polyimide. A membrane with a thickness of 10-500mum is formed from said dope and immersed in a coagulation bath comprising a mixture of an org. liquid freely mixed with the phenolic solvent and water to be coagulated. |
