Semipermeable membranes of heterocyclic copolyamides

Claim 1

A semipermeable membrane with a water absorption capacity of from 4.5 to 11% by weight, as measured on an approximately 40μ thick symmetrical film at room temperature at 65% relative air humidity, a throughflow of from 130 to 200 l/m 2 d for a desalination level of from 94.6 to 99.5% and consisting of an aromatic heterocycle-containing copolyamide (A) 10 to 95 mole% of one or more units corresponding to Formulae I-IV below: ##STR21## in which R, R', R", R"', R IV , R V , R VI and R VII which are the same or different represent hydrogen, C 1-4 -alkyl or halogen; Ar represents an alkyl- or halogen-substituted bivalent aromatic radical or an unsubstituted bivalent aromatic radical; and X, Y and Z, each represent a direct bond or a bridge member selected from the group consisting of ##STR22## and of (B) 5 to 90 mole% of units corresponding to the formula (V) --HN--T--NH--OC--Ar--CO-- (V), in which Ar is as just defined and T represents a bivalent heterocyclic radical which contains one or more aromatic or heterocyclic radicals.