SEMIPERMEABLE OSMOTIC MEMBRANE AND METHOD OF PRODUCING SAME

• US 3,661,634 A
• Filed: 10/31/1969
• Issued: 05/09/1972
• Est. Priority Date: 10/31/1969
• Status: Expired due to Term

• Current Assignee: Clifford R. Lyons, Robert L. Riley
• Original Assignee: Clifford R. Lyons, Robert L. Riley
• Inventors: Riley, Robert L., Lyons, Clifford R.
• Application Number:
  US04/873,116
• Time in Patent Office: 921 Days
• US Class Current: 427/245
• CPC Class Codes: B01D 69/12 Composite membranes; Ultra-thin membranes
• CPC Class Codes: B01D 71/441 Polyvinylpyrrolidone
• CPC Class Codes: C08G 18/302 Water
• CPC Class Codes: C08G 18/6283 Polymers of nitrogen containing compounds having carbon-to-carbon double bonds C08G18/6262, C08G18/6266 take precedence
• CPC Class Codes: C08G 18/8061 masked with compounds having only one group containing active hydrogen
• CPC Class Codes: C08L 2666/10 Homopolymers or copolymers according to C08L39/00 - C08L49/00; Derivatives thereof
• CPC Class Codes: C08L 75/00 Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
• CPC Class Codes: Y10S 521/905 Hydrophilic or hydrophobic cellular product

Abstract

Semipermeable membranes prepared from a mixture of vinylpyrrolidone polymers and polyisocyantes. Process for preparing such membranes by casting the mixture from solution onto a smooth surface followed by curing under conditions of controlled humidity. Reaction of polyisocyanates with certain compounds having an active hydrogen atom provides a '"'"''"'"''"'"''"'"'blocked'"'"''"'"''"'"''"'"' polyisocyanate which does not react immediately with water at ambient temperatures thereby allowing greater processing control of membrane production.

Claims

2. A process according to claim 1 wherein the ratio of blocked isocyanate groups to polymerized vinylpyrrolidone groups is greater than about 0.25.

3. A process according to claim 1 wherein said curing is carried oUt in an atmosphere containing sufficient water vapor to provide said atmosphere with a relative humidity of less than about 20 percent at 25.20 C.

4. A process according to claim 3 wherein said vinylpyrrolidone polymer is a polyvinylpyrrolidone having an average molecular weight in excess of about 100,000, wherein said ratio is between about 0.4 and about 2.0, and wherein said temperature is from about 140* C. to about 175* C.

5. A process according to claim 4 wherein said blocked polyisocyanate is the reaction product of a polyisocyanate with epsilon -caprolactam.

6. A process according to claim 4 wherein said polyisocyanate is a blocked polymethylene polyphenylisocyanate.