Membrane useful for nano-filtration and for separating higher molecular weight compounds of an organic solvent, comprises a photochemically crosslinked polyimide prepared by e.g. reacting imide group of the polyimide with a primary amine

摘要

Membrane formed by phase inversion, comprises at least one photochemically crosslinked polyimide, which is prepared by (1) reacting at least one imide group contained in the polyimide with at least one primary amine of (I) forming polyimide containing at least one primary amino group, and (2) reacting the product of the step (1) with at least one compound of (II) to intercept all the free primary amino groups in the polyimide, which are generated in the step (1). Membrane formed by phase inversion, comprises at least one photochemically crosslinked polyimide, which is prepared by (1) reacting at least one imide group contained in the polyimide with at least one primary amine of formula (NH 2-R-A) (I) forming polyimide containing at least one primary amino group, and (2) reacting the product of the step (1) with at least one compound of formula (B 1>-R11-D 1>) (II) to intercept all the free primary amino groups in the polyimide, which are generated in the step (1). R, R11 : 1-12C alkylene, 1-12C oxyalkylene, 1-12C carboxy-alkylene (all optionally substituted); and A : A 1>or A 2>, which is not primary amino group; A 1>group, which stabilizes a group of the compound (I); A 2>group, which produces radicals under UV irradiation and/or heat; B 1>group, which reacts with a primary amine forming a covalent bond; and D 1>group, which does not react with an amine by forming a covalent bond. An independent claim is also included for producing a membrane by phase inversion, comprising (a) providing a polyimide prepared by the above mentioned method, (b) providing a casting solution comprising (b1) polyimide synthesized in the step (1), (b2) optionally at least one additional polyimide, where the polyimide is same or different from the polyimide, which is used as starting material for producing polyimide synthesized in the step (1), (b3) a solvent system for dissolving the polyimide (b1) and optionally at least one additional polyimide (b2), (b4) optionally an additive for increasing the viscosity of the casting solution, (b5) optionally an additive for suppressing the formation of macropores, and (b6) optionally a surfactant, (c) knife coating a film from the casting solution on a substrate, which is optionally a carrier material, (d) subjecting the film to UV irradiation prior to and/or after precipitating the membrane in a coagulating bath, (e) treating the film in a coagulating bath, where the film before and/or after entering into the coagulation bath is exposed to UV radiation, and (f) optionally washing the membrane.