Kanegafuchi Kagaku Kogyo Kabushiki Kaisha

Masaaki Shimokawa

Tamiyuki Eguchi

Satoshi Imai

Seiichi Mori

A process for preparing a composite amphoteric ion exchange membrane, which comprises forming a thin membrane not exceeding 5 microns thick by applying to a surface of a microporous polymer substrate having a physical, selective permeability of its own, a coating consisting of a polymer having either a cation or anion exchange group and a functional group capable of receiving another ion exchange group having an opposite sign from the cation or anion exchange group or a mixture of two polymers one of which has either a cation or an anion exchange group and the other of which has a functional group capable of receiving an ion exchange group having an opposite sign from the cation or anion exchange group, and introducing the ion exchange group having an opposite sign to said functional group to provide a ratio of anion to cation exchange capacity in the range of from 0.5 to 2.0.

Process for preparing a composite amphoteric ion exchange membrane

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.

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Kobe, Japan

Masaaki Shimokawa