US4828772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microporous membranes of ultrahigh molecular weight polyethylene
Assignee: Entegris Inc
•
Filing: 1988-05-09
•
Granted: 1989-05-09
•
Expires: 2008-05-09
Abstract
Abstract Microporous membranes and methods for producing such membranes from ultrahigh molecular weight polyethylene are described. The method employs extrusion of a solution of UHMW-PE and porogen through a forming die followed by thermal phase separation of polymer and porogen. Microporous structures are created by removing porogen. Microporous membranes produced include membranes with good permeability to air and water making them particularly useful as filtration media and water-resistance breathable membranes.
Inventors
- 👤 George Lopatin
- 👤 Larry Y. Yen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:28
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/28; B; B01; B01D; B01D67/00; B01D67/0002; B01D67/0023; B01D67/003; B01D71/00; B01D71/06; B01D71/26; B01D71/261; B01D71/262; C08J2201/00; C08J2201/02; C08J2201/03; C08J2201/04; C08J2201/052; C08J2201/054; C08J2201/0542; C08J2201/0543; C08J2201/0545; C08J2201/0546; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06; Y; Y10; Y10S; Y10S264/00; Y10S264/48; Y10S264/62
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
109 words
A method for producing a microporous UHMW-PE membrane, including the steps of a. forming a mixture comprising UHMW-PE and a porogen; b. heating the mixture to an elevated temperature to produce a solution of UHMW-PE and porogen; c. extruding the solution of UHMW-PE and porogen through a forming die under moderate shear sufficient to enable employment of conventional extrusion equipment and/or techniques to thereby form a membrane; d. cooling the membrane sufficiently to cause phase separation resulting in a polymer-rich, porogen-poor phase and a polymer-poor, porogen-rich phase in said membrane; e. creating a microporous structure in the membrane by removing porogen from said membrane; f. drying the microporous membrane.
Claim 2
Independent Claim
109 words
A method for producing a microporous UHMW-PE membrane, including the steps of a. forming a mixture comprising UHMW-PE and a porogen; b. heating the mixture to an elevated temperature to produce a solution of UHMW-PE and porogen; c. extruding the solution of UHMW-PE and porogen through a forming die under moderate shear sufficient to enable employment of conventional extrusion equipment and/or techniques to thereby form a membrane; d. cooling the membrane sufficiently to cause phase separation resulting in a polymer-rich, porogen-poor phase and a polymer-poor, porogen-rich phase in said membrane; e. creating a microporous structure in the membrane by removing porogen from said membrane; f. drying the microporous membrane.
Claim 3
Dependent Claim
34 words
A method of claim 1 wherein said UHMW-PE is present in the mixture of UHMW-PE and porogen in an amount of from about 2% to about 20%, by weight, based upon UHMW-PE and porogen.
Claim 4
Dependent Claim
11 words
A method of claim 2 wherein porogen is removed by extraction.
Claim 5
Dependent Claim
19 words
A method of claim 3 wherein the membrane is restrained during extraction to minimize collapse of the microporous structure.
Claim 6
Dependent Claim
19 words
A method of claim 4 wherein the membrane is restrained during drying to minimize collapse of the microporous structure.
Claim 7
Dependent Claim
18 words
A method of claim 5 wherein the membrane is formed by extruding the solution through a slot die.
Claim 8
Dependent Claim
11 words
A method of claim 6 wherein said porogen comprises mineral oil.
Claim 9
Dependent Claim
17 words
A method of claim 7 wherein the membrane is cooled by immersing it in a liquid bath.
Claim 10
Dependent Claim
19 words
A method of claim 7 wherein the membrane is cooled by bringing it into contact with a solid surface.
Claim 11
Dependent Claim
19 words
A method of claim 5 wherein the membrane is formed by extruding the solution through a blown film die.
Claim 12
Dependent Claim
11 words
A method of claim 10 wherein said porogen comprises mineral oil.
Claim 13
Dependent Claim
15 words
A method of claim 11 wherein said hollow fiber membrane formed is cooled with fluid.
Claim 14
Dependent Claim
18 words
A method of claim 10 wherein the membrane formed by the blow film die is cooled with fluid.
Claim 15
Dependent Claim
19 words
A method of claim 5 wherein the membrane is formed by extruding the solution through a hollow fiber die.
Claim 16
Independent Claim
121 words
A method for producing a microporous ultra-high molecular weight polyolefin membrane, including the steps of: a. forming a mixture comprising ultra-high molecular weight polyolefin and a porogen; b. heating the mixture to an elevated temperature to produce a solution of ultra-high molecular weight polyolefin and porogen; c. extruding the solution of ultra-high molecular weight polyolefin and porogen through a forming die under moderate shear sufficient to enable employment of conventional extrusion equipment and/or techniques to thereby form a membrane; d. cooling the membrane sufficiently to cause phase separation resulting in a polymer-rich, porogen-poor phase and a polymer-poor porogen-rich phase in said membrane; e. creating a microporous structure in the membrane by removing porogen from said membrane; f. drying the microporous membrane.
Claim 17
Independent Claim
121 words
A method for producing a microporous ultra-high molecular weight polyolefin membrane, including the steps of: a. forming a mixture comprising ultra-high molecular weight polyolefin and a porogen; b. heating the mixture to an elevated temperature to produce a solution of ultra-high molecular weight polyolefin and porogen; c. extruding the solution of ultra-high molecular weight polyolefin and porogen through a forming die under moderate shear sufficient to enable employment of conventional extrusion equipment and/or techniques to thereby form a membrane; d. cooling the membrane sufficiently to cause phase separation resulting in a polymer-rich, porogen-poor phase and a polymer-poor porogen-rich phase in said membrane; e. creating a microporous structure in the membrane by removing porogen from said membrane; f. drying the microporous membrane.
References Cited (Backward Citations)
US4140815A
Cited
US4057481A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-08 | 1992-11-07 | 1993-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-08 | 1996-11-07 | 1997-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-08 | 2000-11-07 | 2001-05-09 | $7700.00 | Window Closed / Lapsed |