US3661645A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polytetrafluoroethylene battery separator and method for producing same
Assignee: McDonnell Douglas Corp
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Filing: 1970-04-13
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Granted: 1972-05-09
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Expires: 1990-04-13
Abstract
Abstract Method for producing an improved battery separator, specifically a microporous polytetrafluoroethylene separator, having high ionic conductivity, and having a highly uniform porous structure, by mixing an aqueous dispersion of a substance which is insoluble in water and which does not precipitate or coagulate polytetrafluoroethylene from aqueous dispersion, e.g., zinc oxide, with an aqueous dispersion of polytetrafluoroethylene, casting a film of such mixture, drying the film, sintering the dried film, forming a polytetrafluoroethylene film with particles of such substance, e.g., zinc oxide, uniformly distributed in such film, and removing the particles of such substance from the polytetrafluoroethylene film, e.g., removing zinc oxide particles from the film by leaching with aqueous alkali. The resulting flexible film or separator produced by such process.
Inventors
- 👤 Murray P Strier
- 👤 Joseph S Smatko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:33
CPC Classifications
H; H01; H01M; H01M50/00; H01M50/40; H01M50/489; H01M50/409; H01M50/411; H01M50/414; H01M50/426; H01M50/491; H01M50/497; H01M2300/00; H01M2300/0002; H01M2300/0014; Y; Y02; Y02E; Y02E60/00; Y02E60/10
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
30 words
The process as defined in claim 1, including removing said particles of said substance from said polytetrafluoroethylene film by dissolution or leaching of said last mentioned particles from said film.
Claim 2
Dependent Claim
44 words
The process as defined in claim 1, employing particles of a substance in the form of a metal or a compound leachable in alkali or acid, said particles of said substance being removed from said sintered polytetrafluoroethylene film by treatment with alkali or acid.
Claim 3
Dependent Claim
57 words
The process as defined in claim 1, said particles of said substance being selected from the group consisting of zinc, zinc oxide, nickel, nickel oxide, cadmium, cadmium oxide, silver, silver oxide, lead oxide, lead carbonate, silica, glass fibers, and mixtures thereof, said particles of said substance being removed from said film by leaching with alkali or acid.
Claim 4
Dependent Claim
29 words
The process as defined in claim 1, including forming said dispersion by mixing an aqueous suspension of said particles of said substance with an aqueous emulsion of said polytetrafluoroethylene.
Claim 5
Dependent Claim
20 words
The procEss as defined in claim 5, employing an aqueous suspension of zinc oxide and an aqueous emulsion of polytetrafluoroethylene.
Claim 6
Dependent Claim
37 words
The process as defined in claim 6, said mixture of zinc oxide and polytetrafluoroethylene containing about 50 to about 95 percent of said zinc oxide particles and about 50 to about 5 percent of polytetrafluoroethylene, by weight.
Claim 7
Dependent Claim
43 words
The process as defined in claim 1, said particles of said substance being particles of zinc oxide, said particles of zinc oxide being removed from said sintered polytetrafluoroethylene film by treatment of said sintered film with alcoholic alkali, and then with aqueous alkali.
Claim 8
Dependent Claim
52 words
The process as defined in claim 1, said particles of said substance being particles of zinc oxide, said particles of zinc oxide being removed from said sintered polytetrafluoroethylene film by treating said sintered film first with acetone, then with methanol, then with methanolic KOH, and finally with a aqueous solution of KOH.
Claim 9
Dependent Claim
122 words
The process as defined in claim 7, including forming said mixture of particles of zinc oxide and polytetrafluoroethylene by adding an aqueous emulsion of polytetrafluoroethylene to an aqueous suspension of zinc oxide, said zinc oxide particles having a particle size ranging from about 0.1 to about 10 Mu and said polytetrafluoroethylene having a particle size ranging from about 0.01 to about 10 Mu , said drying of said polytetrafluoroethylene film being carried out at temperature of about 40* to about 100* C. for a period of from about 2 to about 24 hours, said sintering of said polytetrafluoroethylene film being carried out at temperature of about 100* to about 375* C. for a period from about 10 minutes to about 2 hours.
Claim 10
Dependent Claim
57 words
The process as defined in claim 10, said sintering of said polytetrafluoroethylene being carried out at temperature ranging from about 230* to about 275* C., and including soaking said sintered film in acetone, then soaking said film in methanol, then soaking said film in saturated methanolic KOH, and finally soaking said polytetrafluoroethylene film in aqueous KOH solution.
Claim 11
Dependent Claim
34 words
A microporous flexible high strength polytetrafluoroethylene battery separator film, said film having high ionic conductivity, resistance to alkali electrolyte, high resistance to oxidation and good thermal stability, produced by the process of claim 1.
Claim 12
Dependent Claim
34 words
A microporous flexible high strength polytetrafluoroethylene battery separator film, said film having high ionic conductivity, resistance to alkali electrolyte, high resistance to oxidation and good thermal stability, produced by the process of claim 9.
Claim 13
Dependent Claim
68 words
A microporous flexible polytetrafluoroethylene battery separator film, said film having high ionic conductivity ranging from about 5 to about 15 ohm-cm, high strength, resistance to alkali electrolyte, high resistance to oxidation, good thermal stability, highly uniform pore distribution with porosity ranging from about 25 percent to about 90 percent, and a film thickness ranging from about 0.2 to about 50 mils, produced by the process of claim 11.
Claim 14
Dependent Claim
45 words
A battery having a pair of electrodes of opposite polarity and a porous separator between said electrodes for retaining electrolyte and permitting transfer of electrolyte ions while inhibiting migration of electrode ions, said separator being a microporous flexible polytetrafluoroethylene film as defined in claim 12.
Claim 15
Dependent Claim
45 words
A battery having a pair of electrodes of opposite polarity and a porous separator between said electrodes for retaining electrolyte and permitting transfer of electrolyte ions while inhibiting migration of electrode ions, said separator being a microporous flexible polytetrafluoroethylene film as defined in claim 14.
Claim 16
Dependent Claim
14 words
A battery as defined in claim 16, said electrodes being zinc and silver electrodes.
Claim 17
Dependent Claim
128 words
The process foR preparing flexible microporous polytetrafluoroethylene film of high ionic conductivity and having uniformly distributed pores, which comprises forming polytetrafluoroethylene occurs, resulting in a polytetrafluoroethylene film homogeneous dispersion of particles of polytetrafluoroethylene and particles of zinc oxide, casting a film of said dispersion, drying said film, sintering said dried film at temperature at which substantially no decomposition of said polytetrafluoroethylene occurs, resulting in a polytetrafluoroethylene film with said particles of zinc oxide bonded by and uniformly distributed in said film, and removing said particles of zinc oxide from said sintered polytetrafluorethylene film by treating said sintered film first with a ketone, then with an alcohol, then with alcoholic alkali, and finally with an aqueous solution of alkali, thereby producing a polytetrafluoroethylene film having uniformly distributed pores therein.
Claim 18
Dependent Claim
35 words
The process as defined in claim 18, including rolling said sintered polytetrafluoroethylene film prior to removing said particles of said zinc oxide, to form a fibrous polytetrafluoroethylene structure binding said particles of said zinc oxide.
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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) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |