Interfacially synthesized reverse osmosis membranes and processes for preparing the same

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The membranes of the present invention may be formed by various methods of interfacial polymerization, a number of which are known in the art.
Presently preferred are the methods described in prior U.
S.
Pat.
Nos.
4,872,984 and 4,948,507, the disclosures of which are incorporated herein by reference.
While the present invention will now be described herein with reference to the preferred method in which the polymerization is carried out in the presence of a monomeric amine salt, it will be understood that the following methods could be carried out without the presence of the monomeric amine salt, which is used in the methods of the prior above-mentioned patents.
In one embodiment, the objects of the present invention have been met by a water permeable membrane produced by the process comprising the steps of: (a) coating a microporous support with an aqueous solution comprising (i) an essentially monomeric polyamine reactant having at least two amine functional groups and (ii) a monomeric amine salt, to form a liquid layer on said microporous support; (b) contacting said liquid layer with an organic solvent solution of an essentially monomeric amine-reactive reactant comprising a polyfunctional single ring cycloaliphatic acyl halide having fewer than six carbon atoms in the ring, or mixture thereof, wherein the amine-reactive reactant has, on the average, at least about 2.
2 acyl halide groups per reactant molecule; and (c) drying the product of step (b) so as to form said water permeable membrane.
In a second embodiment, the water permeable membrane is produced by the process comprising the steps of: (a) coating a microporous support with a first aqueous solution comprising a monomeric amine salt to form a monomeric amine salt layer on said microporous support; (b) coating said monomeric amine salt layer with a second aqueous solution comprising an essentially monomeric polyamine reactant having at least two amine functional groups to form a liquid layer on said monomeric amine salt layer; (c) coating said liquid layer with an organic solvent solution of an essentially monomeric amine-reactive reactant, comprising a polyfunctional single ring cycloaliphatic acyl halide having fewer than six carbon atoms in the ring, or mixture thereof, wherein the amine-reactive reactant has, on the average, at least about 2