High performance semipermeable composite membrane and process for producing same

Claim 2

A high performance semipermeable composite membrane with (a) a microporous substrate, (b) an intermediate transport layer comprising a crosslinked polymer made from a water soluble polymer (x), formed upon and affixed to said microporous substrate, (c) an ultrathin solute rejection barrier layer comprising (i) an inner portion affixed to said intermediate transport layer and comprising a crosslinked polymer made from the reaction product of a water soluble polymer (x) and a monomer (y) with a crosslinking agent (z), (ii) an outer portion affixed to said inner portion (i) and comprising a crosslinked polymer made from the monomer (y) with the crosslinking agent (z), wherein said water soluble polymer (x) has a reactive amino or hydroxyl groups, said monomer (y) has at least two amino groups on an aromatic nucleus comprising from 1 to 3 aromatic rings, and said crosslinking agent (z) has at least 3 acyl halide groups on an aromatic nucleus comprising from 1 to 3 aromatic rings.

Claim 3

The membrane defined in claim 1, wherein said layer (c) has a controlled and substantially uniform 0 thickness of about 100 to 1,OOOA.

Claim 4

The membrane defined in Claim 1, wherein said water soluble polymer (x) is selected from the group consisting of amine modified polyepihalohydrin, polyethylene imine, polyepiaminohydrin and polyvinyl alcohol.

Claim 5

The membrane defined in Claim 3, wherein said amine modified polyepihalohydrin is a modified polymer made by reacting at least one polyepihalohydrin represented by the formula (I); wherein the X is a halogen selected from the group consisting of Cl, Br and I, and i and j are mole fractions and satisfy the following relationships: with at least one monomeric polyamine (II) which is a non-cyclic or cyclic polyamine containing: 1) 0 to 1 amino group, 2) more than 1 imino group, and in which 3) the sum of the amino group and the imino groups is more than 2, wherein the amino group when present is bonded to a carbon atom and the imino groups are bonded to one to two carbon atoms, the total number of carbon atoms being 3 to 12.

Claim 6

The membrane defined in Claim 4, wherein the monomeric polyamine (II) is 4-(aminomethyl)piperidine.

Claim 7

The membrane defined in Claim 1, wherein the monomer (y) is selected from the group consisting of phenylene diamine, diaminodiphenylether, diaminodiphenylsulfone, diaminodiphenylmethane and tetraaminodiphenylmethane.

Claim 8

The membrane defined in Claim 1, wherein the said crosslinking agent (z) is selected from the group consisting of trimesoyl chloride and trimellitic acid chloride.

Claim 9

The membrane defined in Claim 1, wherein said membrane intermediate transport layer has a thickness 0 of about 100A to 3 microns.

Claim 10

The membrane defined in Claim 1, wherein said 0 ultrathin solute barrier layer (c) is about 100A to 1000A in thickness and said intermediate transport layer (b) is about 100A to 3 microns in thickness.

Claim 11

The membrane defined in Claim 1, wherein said microporous substrate (a) comprises an organic polymer selected from the group consisting of polysulfone, chlorinated polyolefin, cellulose acetate and polyvinyl chloride, being optimally reinforced by a material selected from the group consisting of calendered woven fabric, calendered non-woven fabric, uncalendered woven fabric uncalendered non-woven fabric, porous film and paper.

Claim 12

The membrane defined in Claim 1, wherein the membrane is protected by a crosslinked polymer selected from the group consisting of polyvinyl alcohol, partially saponified polyvinyl acetate, and polyvinyl pyrrolidone.

Claim 13

The membrane defined in Claim 11, wherein the 0 protective coating has a thickness of about 1000A to about 10 microns.

Claim 14

A process for producing a high performance semipermeable composite membrane according to any of claims 1 to 12 comprising the steps of: (1) covering the surface of (a) a microporous substrate with an aqueous solution containing at least (x) one water-soluble polymer having reactive amino or hydroxyl groups, said aqueous solution also containing (y) the monomer having at least two amino groups on an aromatic nucleus comprising 1 to 3 aromatic ring (5); (2) covering the resulting coated porous substrate with a solution which is substantially immiscible with the solution of step (1) and which contains (z) a crosslinking agent having at least 3 acyl halide groups on an aromatic nucleus comprising 1 to 3 aromatic rings and being capable of undergoing interfacial polymerization with said reactive groups of the water-soluble polymer and with said monomer to form an ultrathin film on said surface of said microporous substrate; (c) continuing said interfacial polymerization reaction for a time sufficient to cause migration of at least a portion of said monomer through the inner portion of the ultrathin film, thereby reacting with said crosslinking agent to form an outer portion of the ultrathin polymeric layer on the inner portion of the ultrathin layer being formed; and (d) drying the resulting composite semipermeable membrane at elevated temperature for a time sufficient to crosslink said water-soluble polymer.

Claim 15

The process defined in claim 13, wherein the aqueous solution contains a mixture consisting of about 10 % to about 90 % by weight of the water soluble polymer and of about 90 % to about 10 % by weight of the monomer.

Claim 16

The process defined in Claim 13, wherein the concentration of the aqueous solution is in the range of about 0.1% to 10% by weight.