US3607754A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High molecular weight electrets and process for producing them
Assignee: Kureha Corp
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Filing: 1969-12-09
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Granted: 1971-09-21
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Expires: 1989-12-09
Abstract
Abstract An electret comprising a resin mixture of from 50 to 90 percent by weight of a vinylidene fluoride resin and from 10 to 50 percent by weight of a methyl methacrylate resin, said resin mixture having been subjected to polarization.
Inventors
- 👤 Mitsuo Asahina
- 👤 Haruko Kakutani
- 👤 Kinuko Wada
- 👤 Masahiko Tamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:59
CPC Classifications
H; H01; H01B; H01B3/00; H01B3/18; H01B3/30; H01B3/44; H01B3/447; H01B3/443; H01B3/445; H01G; H01G7/00; H01G7/02; H01G7/021; H01G7/023; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49226
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
31 words
The electret as in claim 1 wherein said vinylidene fluoride resin is selected from the group consisting of polyvinylidene fluoride and a copolymer containing more than 70% by weight polyvinylidene fluoride.
Claim 2
Dependent Claim
31 words
The electret as in claim 2 wherein said copolymer is a copolymer of vinylidene fluoride and a member selected from the group consisting of vinyl fluoride, ethylene trifluoride, and ethylene tetrafluoride.
Claim 3
Dependent Claim
52 words
The electret as in claim 1 wherein said methyl methacrylate resin is selected from the group consisting of homopolymer of methyl methacrylate and a copolymer of methyl methacrylate and less than 25 mole% of a monomer selected from the group consisting of an alkyl methacrylate, styrene, Alpha -methylstyrene, acrylonitrile and alkyl acrylate.
Claim 4
Dependent Claim
35 words
The electret as in claim 1 wherein said polarization is conducted by applying a direct current potential to said resin mixture at a temperature of from 80 to 160* C., followed by cooling the mixture.
Claim 5
Dependent Claim
29 words
The electret as in claim 1 wherein said polarization is conducted by applying a direct current potential to said resin at a temperature of from 100 to 135* C.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |