COMPOSITE MEMBRANE AND PROCESS FOR MAKING SAME

• US 3,556,305 A
• Filed: 03/28/1968
• Issued: 01/19/1971
• Est. Priority Date: 03/28/1968
• Status: Expired due to Term

• Current Assignee: WR Grace & Company
• Original Assignee: Jacob Shorr
• Inventors: Shorr, Jacob
• Application Number:
  US04/717,039
• Time in Patent Office: 1,027 Days
• US Class Current: 210/490
• CPC Class Codes: B01D 69/12 Composite membranes; Ultra-thin membranes
• CPC Class Codes: B01D 69/1214 Chemically bonded layers, e.g. cross-linking
• CPC Class Codes: B01D 69/1216 Three or more layers
• CPC Class Codes: B01D 69/14 Dynamic membranes
• CPC Class Codes: Y10T 428/24998 Composite has more than two layers
• CPC Class Codes: Y10T 428/264 Up to 3 mils
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

A novel membrane suitable for use in reverse osmosis and related separation processes, said membrane comprising (a) an anisotropic membrane comprising a thin microporous barrier skin and a thicker macroporous support layer, (b) a very thin layer of a film forming adhesive polymer over the barrier skin of hydraulically porous substrate and (c) a very thin diffusive type membrane film overlying said adhesive polymer and bound to said porous substrate by said adhesive polymer.

Claims

2. A membrane as defined in claim 1 wherein the maximum thickness of said adhesive polymeric layer is about 500 angstroms.

3. a diffusive polymer or gellike film bonded to said barrier layer of said porous substrate by said adhesive layer.

4. A membrane as defined in claim 1 wherein said diffusive film is polyvinyl alcohol or a mixture of polyvinyl methyl ether with a copolymer of methyl vinyl ether with maleic anhydride.

5. A membrane as defined in claim 1 wherein the composite thickness of said adhesive layer and a diffusive film overlying said layer is less than about 2 microns.

6. A membrane as defined in claim 1 wherein said porous substrate is formed of a polysulfone polymer.

7. A process for making a membrane suitable for use in ultrafiltration, reverse osmosis, and other such separation processes which coMprises providing a porous substrate formed of a highly anisotropic polymeric membrane having a. a barrier layer at one surface thereof comprising micropores from 15 to 1,000 angstroms in diameter and having a thickness from about 0.1 to 5 microns and b. a macroporous support layer, coating said substrate with a solution of an adhesive polymer to thereby deposit on the surface of the substrate an adhesive polymeric layer having a maximum thickness of about 1,500 angstroms, and filtering through said substrate from the surface having the barrier layer a dilute solution of polymer or gellike material to form a diffusive film bonded to said adhesive layer.