High performance semipermeable composite membrane and process for producing the same

Claim 2

A high performance semipermeable composite memebrane comprising: (a) a microporous substrate; (b) an intermediate transport layer comprising a cross-linked polymer made from a water soluble polymer, formed upon and affixed to said microporous substrate; and (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 and a monomer with a crosslinking agent, and (ii) an outer portion affixed to said inner portion (i) and comprising a crosslinked polymer made from the monomer with the crosslinking agent, wherein said water soluble polymer has a reactive amino or hydroxyl group, said monomer has at least two amino groups on an aromatic nucleus comprising from 1 to 3 aromatic carbon rings, and said crosslinking agent has at least 3 acylhalide groups on an aromatic nucleus comprising from 1 to 3 aromatic carbon rings.

Claim 3

The membrane defined in claim 1, wherein said ultrathin solute rejection barrier layer has a controlled and substantially uniform thickness of about 100 to 1,000 A.

Claim 4

The membrane defined in claim 1, wherein said water soluble polymer is selected from the group consisting of amine modified polyepihalohydrin, polyethyleneimine, polyepiaminohydrin and polyvinylalcohol.

Claim 5

The membrane defined in claim 1, wherein said water soluble polymer is amine modified polyepiaminohydrin.

Claim 6

The membrane defined in claim 4, wherein said amine modified polyepihalohydrin is a modified polymer of polyepihalohydrin with a monomeric polyamine.

Claim 7

The membrane defined in claim 4, wherein said amine modified polyepihalohydrin is a modified polymer made by reacting at least one polyepihalohydrin represented by the formula (I); ##STR2## 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: i+j=1 < i≦1 0≦j<0.8 with at least one monomeric polyamide (ii) which is a non-cyclic or cyclic polyamine containing: (1) from 0 to 1 amino group, (2) more than 1 imino group, and (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 to the imino groups are bonded to from one to two carbon atoms, the total number of carbon atoms being from 3 to 12.

Claim 8

The membrane defined in claim 6, wherein the monomeric polyamine (II) is 4-(aminomethyl)piperidine.

Claim 9

The membrane defined in claim 6, wherein said polyepihalohydrin(I) is selected from the group consisting of polyepichlorohydrin, polyepibromohydrin and polyepiiodohydrin.

Claim 10

The membrane defined in claim 1, wherein the monomer is selected from the group consisting of phenylenediamine, diaminodiphenylether, diaminodiphenylsulfone, diaminodiphenylmethane and tetraaminodiphenylmethane.

Claim 11

The membrane defined in claim 9, wherein said monomer is phenylenediamine.

Claim 12

The membrane defined in claim 9, wherein said monomer is m-phenylenediamine.

Claim 13

The membrane defined in claim 1, wherein said crosslinking agent is selected from the group consisting of trimesoylchloride and trimellitic acid chloride.

Claim 14

The membrane defined in claim 12, wherein said crosslinking agent is trimesoylchloride.

Claim 15

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

Claim 16

The membrane defined in claim 1, wherein said ultrathin solute barrier layer is about 100 Å to 1000 Å in thickness and said intermediate transport layer is about 100 Å to 3 microns in thickness.

Claim 17

The membrane defined in claim 1, wherein said microporous substrate comprises an organic polymer selected from the group consisting of polysulfone, chlorinated polyolefin, cellulose acetate and polyvinylchloride.

Claim 18

The membrane defined in claim 1, wherein the microporous substrate is 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 19

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 20

The membrane defined in claim 18, wherein the protective coating has a thickness of about 1000 Å to about 10 microns.

Claim 21

A process for producing a high performance semipermeable composite membrane comprising the steps of: (a) covering the surface of a microporous substrate with an aqueous solution containing at least one water soluble polymer having reactive amino or hydroxyl groups, said aqueous solution also containing a monomer having at least two amino groups on an aromatic compound comprising from 1 to 3 aromatic carbon ring(s); (b) covering the resulting coated porous substrate with a solution which is substantially immiscible with the solution of step (a) and which contains a crosslinking agent having at least 3 acylhalide groups on an aromatic compound comprising from 1 to 3 aromatic carbon rings 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 aromatic polyamine through an inner portion of the ultrathin film, thereby reacting said aromatic polyamine with said crosslinking agent to form an outer portion of an ultrathin polymeric layer on the inner portion of the ultrathin layer being formed; and (d) drying the resulting composite semipermeable membrane at an elevated temperature for a time sufficient to cross-link said water-soluble polymer.

Claim 22

A process for producing a high performance semipermeable composite membrane comprising the steps of: (a) covering the surface of a microporous substrate with an aqueous solution containing at least one water soluble polymer having reactive amino or hydroxyl groups, said aqueous solution also containing a monomer having at least two amino groups on an aromatic compound comprising from 1 to 3 aromatic carbon ring(s); (b) covering the resulting coated porous substrate with a solution which is substantially immiscible with the solution of step (a) and which contains a crosslinking agent having at least 3 acylhalide groups on an aromatic compound comprising from 1 to 3 aromatic carbon rings 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 aromatic polyamine through an inner portion of the ultrathin film, thereby reacting said aromatic polyamine with said crosslinking agent to form an outer portion of an ultrathin polymeric layer on the inner portion of the ultrathin layer being formed; and (d) drying the resulting composite semipermeable membrane at an elevated temperature for a time sufficient to cross-link said water-soluble polymer.

Claim 23

The process defined in claim 20, wherein said water-soluble polymer is selected from the group consisting of amine modified polyepihalohydrin, polyethyleneimine, polyepiaminohydrin and polyvinylalcohol.

Claim 24

The process defined in claim 20, wherein said water-soluble polymer is an amine modified polyepihalohydrin.

Claim 25

The process defined in claim 22, wherein said amine modified polyepihalohydrin is a modified polymer of polyepihalohydrin with a monomeric polyamine.

Claim 26

The process defined in claim 23, wherein said amine modified polyepihalohydrin is a modified polymer made by reacting at least one polyepihalohydrin represented by the formula (I): ##STR3## wherein 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; i+j=1 < i≦1 0≦j<0.8; with at least one monomeric polyamine (ii) which is a non-cyclic or cyclic polyamine containing; (1) from 0 to 1 amino group, (2) more than 1 imino group, and (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 from one to two carbon atoms, the total number of the carbon atoms being from 3 to 12.

Claim 27

The process defined in claim 24, wherein the monomeric polyamine (II) is 4-(aminomethyl)piperidine.

Claim 28

The process defined in claim 24, wherein the epihalohydrin (I) is selected from the group consisting of polyepichlorohydrin, polyepibromohydrin and polyepiiodohdrin.

Claim 29

The process defined in claim 20, wherein the monomer is selected from the group consisting of phenylenediamine, diaminodiphenylether, diaminodiphenylsulfone, diaminodiphenylmethane and tetraaminodiphenylmethane.

Claim 30

The process defined in claim 20, wherein said monomer is phenylenediamine.

Claim 31

The process defined in claim 20, wherein said monomer is m-phenylenediamine.

Claim 32

The process defined in claim 20, wherein said crosslinking agent is selected from the group consisting of trimesoylchloride and trimellitic acid chloride.

Claim 33

The process defined in claim 20, wherein said crosslinking agent is trimesoylchloride.

Claim 34

The process defined in claim 20, wherein said microporous substrate comprises an organic polymer selected from the group consisting of polysulfone, chlorinated polysulfone, cellulose acetate and polyvinylchloride.

Claim 35

The process defined in claim 20, wherein said microporous substrate comprises polysulfone.

Claim 36

The process defined in claim 20, wherein said microporous substrate is 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 37

The process defined in claim 20, wherein the membrane is protected by a crosslinked polymer selected from the group consisting of polyvinyl alcohol, partially saponified polyvinyl acetate and polyvinylpyrrolidone.

Claim 38

The process defined in claim 20, wherein the mixture contains from about 10% to about 90% by weight of the water soluble polymer and about 90% to 10% by weight of the monomer.

Claim 39

The process defined in claim 20, wherein the concentration of the aqueous solution is in the range of about 0.1% to 10% by weight.