US4170540A
Expired / Lapsed
US
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Method for forming microporous membrane materials
Assignee: Occidental Chemical Corp
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Filing: 1978-03-31
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Granted: 1979-10-09
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Expires: 1998-03-31
Abstract
Abstract Microporous membrane materials suitable for electrolytic cell utilization are formed from the blend of particulate polytetrafluoroethylene, a dry pore forming particulate material, and an organic lubricant. The materials are milled and formed into a sheet, which is rolled to the desired thickness, sintered, and subjected to leaching of the pore forming materials.
Inventors
- 👤 Christine A. Lazarz
- 👤 Edward H. Cook, Jr.
- 👤 Lesleigh V. Scripa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:17
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/26; C25; C25B; C25B13/00; C25B13/04; C25B13/08; H; H01; H01M; H01M50/00; H01M50/40; H01M50/403; H01M50/406; H01M50/409; H01M50/411; H01M50/414; H01M50/426; H01M50/489; H01M50/491; H01M50/494; C08J2327/00; C08J2327/02; C08J2327/12; H01M2300/00; H01M2300/0002; H01M2300/0014; Y; Y02; Y02E; Y02E60/00; Y02E60/10
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
105 words
A process for the preparation of a microporous electrolytic cell separator, comprising the steps of: (a) blending a dry fluorocarbon polymer powder and a pore forming particulate additive; (b) adding an organic nonionic fluorosurfactant lubricant; (c) blending said polymer powder, particulate additive and lubricant to a uniform mixture; (d) forming said mixture into a sheet; (e) reducing said sheet to the desired thickness by passing between rollers a plurality of times; (f) heating said sheet to remove volatile components in the lubricant; (g) sintering and cooling said sheet material; and (h) removing the particulate pore forming additive forming a high porosity microporous electrolytic cell separator.
Claim 2
Dependent Claim
105 words
A process for the preparation of a microporous electrolytic cell separator, comprising the steps of: (a) blending a dry fluorocarbon polymer powder and a pore forming particulate additive; (b) adding an organic nonionic fluorosurfactant lubricant; (c) blending said polymer powder, particulate additive and lubricant to a uniform mixture; (d) forming said mixture into a sheet; (e) reducing said sheet to the desired thickness by passing between rollers a plurality of times; (f) heating said sheet to remove volatile components in the lubricant; (g) sintering and cooling said sheet material; and (h) removing the particulate pore forming additive forming a high porosity microporous electrolytic cell separator.
Claim 3
Dependent Claim
11 words
The process of claim 1, wherein said fluorocarbon polymer is polytetrafluoroethylene.
Claim 4
Dependent Claim
22 words
The process of claim 2 wherein said material is formed into a sheet by passage between the rolls of a roll mill.
Claim 5
Dependent Claim
15 words
The process of claim 3 wherein said material is formed into a sheet by extrusion.
Claim 6
Dependent Claim
12 words
The process of claim 2, wherein the lubricant is fluoroalkyl poly(ethyleneoxy) ethanol.
Claim 7
Dependent Claim
26 words
The process of claim 2 wherein said lubricant is present in an amount of from about 5 to about 30 percent by weight of the mixture.
Claim 8
Dependent Claim
25 words
The process of claim 6 wherein said particulate additive and said polymer are present in a weight ratio of from about 10:1 to about 1:1.
Claim 9
Dependent Claim
33 words
The process of claim 7 wherein said sheet material is subjected to no more than a single reorientation of 90° between two successive passages between rollers so as to increase biaxial tensile strength.
Claim 10
Dependent Claim
26 words
The process of claim 2 wherein said lubricant is present in an amount of from about 18 to about 23 percent by weight of the mixture.
Claim 11
Dependent Claim
25 words
The process of claim 9 wherein said particulate additive and said polymer are present in a weight ratio of from about 5:1 to about 1:1.
Claim 12
Dependent Claim
41 words
The process of claim 2 wherein said sheet material is heated to a temperature of from about 100° C. to about 250° C. to remove volatilizable components, and sintered at a temperature of from about 340° C. to about 360° C.
Claim 13
Dependent Claim
19 words
The process of claim 2 wherein said polymer powder has an average particle size of less than 100 microns.
Claim 14
Dependent Claim
12 words
The process of claim 2 wherein the particulate additive is calcium carbonate.
Claim 15
Dependent Claim
17 words
The process of claim 12 wherein the particulate additive is removed by leaching with a mineral acid.
Claim 16
Dependent Claim
74 words
A chlor-alkali cell separator comprising a microporous polytetrafluoroethylene sheet having high porosity, said separator formed by blending a dry powder of polytetrafluoroethylene and a particulate pore forming additive with a nonionic fluorosurfactant lubricant to a uniform mixture, forming the mixture into a sheet of the desired thickness by sequentially rolling and rerolling said mixture, drying the sheet to remove volatile components in the lubricant, sintering the polytetrafluoroethylene, and leaching the particulate pore forming additive.
Claim 17
Dependent Claim
74 words
A chlor-alkali cell separator comprising a microporous polytetrafluoroethylene sheet having high porosity, said separator formed by blending a dry powder of polytetrafluoroethylene and a particulate pore forming additive with a nonionic fluorosurfactant lubricant to a uniform mixture, forming the mixture into a sheet of the desired thickness by sequentially rolling and rerolling said mixture, drying the sheet to remove volatile components in the lubricant, sintering the polytetrafluoroethylene, and leaching the particulate pore forming additive.
Claim 18
Dependent Claim
16 words
A separator as set forth by claim 15 having a porosity of greater than 70 percent.
Claim 19
Dependent Claim
15 words
A separator as set forth by claim 15 having a porosity greater than 80 percent.
Claim 20
Dependent Claim
41 words
A separator as set forth by claim 15 wherein said mixture comprises from about 5 to about 30 weight percent lubricant, and said particulate additive and said polytetrafluoroethylene are present in a weight ratio of from about 10:1 to about 5:1.
Claim 21
Dependent Claim
15 words
A separator as set forth by claim 15 wherein said lubricant is fluoroalkyl poly(ethyleneoxy) ethanol.
Claim 22
Dependent Claim
15 words
A separator as set forth in claim 17 wherein said particulate additive is calcium carbonate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-10-08 | 1983-04-09 | 1983-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-10-08 | 1987-04-09 | 1987-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-10-08 | 1991-04-09 | 1991-10-09 | $7700.00 | Window Closed / Lapsed |