| 摘要 |
PURPOSE:To enhance a separation degree without lowering a permeation speed, in preparing a membrane, by adding a specific aromatic 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 polymer is dissolved in a phenolic solvent, especially, halogenated phenol with a b.p. of 300 deg.C or less to prepare a dope. Aromatic carboxylic acid such as naphtoenic acid, biphenyl carboxylate or anthracene carboxylate is added to said dope solution in an amount of 5-40wt% of a polyimide. A membrane with a thickness of 10-500mum is formed from said dope and immersed in a coagulation bath consisting of an org. liquid freely mixed with the phenolic solvent and water to be coagulated. |
