Ion-exchange group bearing composite membranes
AssigneeKanegafuchi Kagaku Kogyo Kabushiki Kaisha
InventorsSatoshi Imai, Tamiyuki Eguchi, Masaaki Shimokawa
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Abstract
Composite membranes bearing ion-exchange groups suitable for use in membrane separation processes are produced by providing a porous substrate which is physically semipermeable by itself, applying a coating composition consisting essentially of a filmforming polymeric material to which ion-exchange groups are introduceable and a liquid medium onto the surface of said substrate, removing said liquid medium to provide an ultrathin membrane of said material having a thickness less than 10 microns, and treating said ultrathin membrane to provide said ion-exchange groups throughout said ultrathin membrane.
Claims19
A method for preparing a selectively permeable composite membrane having an ultrathin layer of ion exchange polymer film adhered to a polymeric microporous supporting substrate which is permeable to ions and molecules which pass through said ultrathin layer, which comprises:
- a. coating said substrate with a composition consisting essentially of an inert diluent and a film-forming polymer which is substantially impermeable to said substrate and which contains at least on reactive site selected from the group consisting of benzene rings, double bonds, halogen atoms, hydroxyl groups or nitrile groups;
- b. removing said inert diluent to form an ultrathin layer of said film-forming polymer having a dry thickness of less than 10 microns adhered to said substrate;
- and
- c. converting said ultrathin layer into an ion exchange layer by chemically introducing ion exchange groups into said reactive sites.
Dependencies are inferred from the claim text.