Patent US1717969A successfully refreshed from Google Patents.
US4003818A
Expired / Lapsed
US
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Method of obtaining a micro-porous membrane and novel product thus obtained
Assignee: Rhone Poulenc Industries SA
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Filing: 1975-07-31
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Granted: 1977-01-18
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Expires: 1995-07-31
Abstract
Abstract A method of obtaining a micro-porous membrane is provided as well as the improved membrane. Said method is characterized in that a homogeneous paste is prepared from a pore-forming filler substance and a latex, and said paste, which is reduced to powder form, is dried and a membrane is formed therefrom and then (fritted) sintered, and the pore-forming filler substance is then removed. The membrane thus obtained is particularly useful as a diaphragm for electrolysis cells.
Inventors
- 👤 Michel Juillard
- 👤 Pierre Bouy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:36
CPC Classifications
C; C25; C25B; C25B13/00; C25B13/04; C25B13/08
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
85 words
A method of producing a micro-porous membrane, characterized in that a homogeneous paste is first formed from a pore-forming particulate filler material and a latex of a fluorinated polymeric resin, said paste is dried in order to obtain a material containing between about 0.1 and 1% of water and the resulting material is reduced to powder form, the product so obtained is preformed and a membrane is formed by rolling said preform, the membrane thus obtained is sintered and the pore-forming particulate filler material removed.
Claim 2
Independent Claim
85 words
A method of producing a micro-porous membrane, characterized in that a homogeneous paste is first formed from a pore-forming particulate filler material and a latex of a fluorinated polymeric resin, said paste is dried in order to obtain a material containing between about 0.1 and 1% of water and the resulting material is reduced to powder form, the product so obtained is preformed and a membrane is formed by rolling said preform, the membrane thus obtained is sintered and the pore-forming particulate filler material removed.
Claim 3
Dependent Claim
20 words
A method of producing a micro-porous membrane according to claim 1, wherein the pore-forming particulate filler material is calcium carbonate.
Claim 4
Dependent Claim
21 words
A method according to claim 2, wherein the calcium carbonate has a particle size of between about 2 and 20 microns.
Claim 5
Dependent Claim
20 words
A method of obtaining a micro-porous membrane according to claim 1, wherein the latex is an aqueous dispersion of polytetrafluoroethylene.
Claim 6
Dependent Claim
17 words
A method according to claim 4, wherein the aqueous dispersion contains between about 40 and 80% polytetrafluoroethylene.
Claim 7
Dependent Claim
42 words
A method of obtaining a micro-porous membrane according to claim 1, wherein, for each part by weight of latex, there are employed from about 3 to 10 parts of pore-forming filler material and about 0.1 to 0.5 of a part of water.
Claim 8
Dependent Claim
184 words
A method of obtaining a micro-porous membrane according to claim 1, wherein the homogeneous paste, comprising the particulate pore forming filler material calcium carbonate and polytetrafluoroethylene, is dried, after mixing, at a temperature of about 80° to 120° C. for a period of about 4 to 10 hours so as to obtain a product containing 0.1 to 1% of water, a preformed product is formed which is subjected to heat treatment at a temperature of between about 150° and 180° C. for a period of between about 0.5 and 2 hours, whereafter said preformed product is rolled at a temperature of between about 130° and 180° C., the membrane thus obtained is subjected to a sintering operation at a temperature of between about 330° and 365° C. for a period of between about 2 and 20 min., the pore-forming filler material is then removed by immersion in an aqueous solution containing about 20 to 30% by weight of a weak acid for a period of between about 24 hours and 15 days, and the micro-porous membrane is subjected to a degassing and wetting treatment.
Claim 9
Dependent Claim
19 words
A method of obtaining a micro-porous membrane according to claim 7, wherein wetting is carried out in methyl alcohol.
Claim 10
Dependent Claim
34 words
A method of obtaining a micro-porous membrane according to claim 1, wherein, prior to the sintering operation, the membrane obtained from the rolling operation is placed as a layer on a permeable reinforcing support.
Claim 11
Dependent Claim
14 words
A micro-porous membrane for use in electrolysis made by the process of claim 1.
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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) | 1980-01-18 | 1980-07-19 | 1981-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-18 | 1984-07-19 | 1985-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-18 | 1988-07-19 | 1989-01-18 | $7700.00 | Window Closed / Lapsed |