Multilayer reverse osmosis membrane of polyamide-urea

Abstract

The present invention is directed to an improved reverse osmosis membrane that shows surprisingly improved solute rejection and permeation properties. The membrane includes a separating layer of a polyamideurea formed in situ by reaction of isocyanate-substituted acyl chloride and a diamine-treated microporous substrate.

What is claimed is: 
     
       1. A reverse osmosis membrane that shows improved salt rejection, flux, and productivity, comprising a polyamideurea separating layer in contact with a .[.polysulfone.]. substrate, wherein said polyamideurea comprises the formula: ##STR2## where m,n>0,   m+n≧3,   X=a (m+n) valent organic group, and   Y=a divalent organic group.   
     
     
       2. The membrane of claim 1 wherein said membrane has a percent salt rejection of at least about 90%. 
     
     
       3. The membrane of claim 1 wherein said membrane has a percent salt rejection of at least about 99%. 
     
     
       4. The membrane of claim 1 further comprising a support member for support said substrate having said separating layer thereon. 
     
     
       5. The membrane of claim 4 wherein said support member is selected from the group of porous glass, sintered metal, ceramics, polyolefins, polyesters, and polyamides. 
     
     
       6. The membrane of claim 3 wherein said support member is polyester. 
     
     
       7. The membrane of claim 1 wherein said membrane is in the form of a hollow fiber. .Iadd.8. The membrane of claim 1 wherein said substrate is a microporous substrate. .Iaddend. .Iadd.9. The membrane of claim 8 wherein said polyamide-urea is the reaction product of monoisocyanate-substituted aromatic diacyl halide and an aromatic diamine. .Iaddend. .Iadd.10. The membrane of claim 8 wherein said polyamide-urea is the reaction product of 1,3,5-substituted monoisocyanato isophthaloyl halide and meta or para-phenylenediamine. .Iaddend. .Iadd.11. The membrane of claim 8 wherein said polyamide-urea is the reaction product of ICIC and meta-phenylenediamine. .Iaddend. .Iadd.12. The membrane of claim 8 wherein said polyamide-urea is the reaction product of a diisocyanate-substituted aromatic acyl halide and an aromatic diamine. .Iaddend. .Iadd.13. The membrane of claim 1 wherein said substrate is made of polysulfone. .Iaddend. .Iadd.14. The membrane of claim 1 wherein X is a trivalent organic group. .Iaddend. .Iadd.15. The membrane of claim 14 wherein Y is a divalent meta- or para-substituted benzene group. .Iaddend. .Iadd.16. The membrane of claim 15 wherein X is a 1,3,5-substituted benzene group. .Iaddend. .Iadd.17. The membrane of claim 8 wherein said polyamide-urea is the reaction product of a trivalent, isocyanate-substituted acyl halide and a divalent cyclic amine. .Iaddend.