process for the production of selectively ion durchlassenden, ionenaustauschenden substances existing slides

摘要

A selective ion-permeable membrane comprising a hydrophilic sheet of a synthetic ionexchange polymer having an integral hydrophobic margin of the same polymer as the sheet but containing no ionogenic groups is produced by subjecting a hydrophobic sheet of polyethylene to a chemical treatment, e.g. with a liquid to introduce ionogenic groups into the sheet, the margin being either protected from the liquid, e.g. by being held out of contact therewith, or by being thicker than the rest of the sheet whereby an untreated core is left in the margin. In an example, a strip of polyethylene is passed continuously through chlorosulphonic acid, e.g. at 30 DEG C. to 40 DEG C., the edges of the strip being upturned to avoid contact with the acid. Specification 747,948 is referred to.