| 摘要 |
<p>An amphoteric ion-permeable composite membrane comprises a microporous substrate, and supported on the substrate, a thin amphoteric ion-exchange film formed of an active amino group-containing polymer which has been interfacially crosslinked at least at the surface portion of the thin film, said membrane being produced by forming a thin layer comprising an active amino group-containing polymer containing 1.0 to 23 milliequivalents/g, as amino equivalent, of an active amino group selected from primary and secondary amino groups and 0 to 18 milliequivalents/g, as amino equivalent, of a tertiary amino group and/or an ammonium salt group per molecule with the total amino content thereof being in the range of 2.0 to 23 milliequivalents/g on the microporous substrate and then contacting the thin layer on the substrate interfacially with a polyfunctional aromatic compound containing at least two functional groups selected from carbonyl halide groups, sulfonyl halide groups, carboxylic acid anhydride groups, sulfonic acid anhydride groups and derivative groups of carboxylic acids and sulfonic acids having equivalent reactivity to the aforesaid halide and anhydride groups. The resulting membrane is particularly suitable for selective filtration of water soluble compounds of similar molecular size, e.g. sodium chloride and sucrose. Membrane properties can be improved still further by heat-treatment.</p> |
