US3755043A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electret having improved stability
Assignee: Kureha Corp
•
Filing: 1970-09-10
•
Granted: 1973-08-28
•
Expires: 1990-09-10
Abstract
Abstract In a process for the production of an electret composed of a high molecular weight base material by applying to the base material a high D. C. potential at a high temperature, cooling the material while continuing the application of the potential, and then removing the electric potential, the improvement which comprises covering the opposite surfaces of the base material before polarizing the base material with thin films of a different high molecular weight material having a higher electrical insulating property than that of the base material prior to the application of the electric potential.
Inventors
- 👤 Y Igarashi
- 👤 H Kakutani
- 👤 M Suzuki
- 👤 M Fukuda
- 👤 T Abe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:19
CPC Classifications
H; H01; H01G; H01G7/00; H01G7/02; H01G7/021; H01G7/023; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49226
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
41 words
The process as in claim 1 wherein said base material is a mixture of polyvinylidene fluoride and polymethyl methacrylate and said different high molecular weight material is selected from the group consisting of polytetrafluoroethylene, polystyrene, polymethyl methacrylate, polyethylene terephthalate, and polypropylene.
Claim 2
Dependent Claim
56 words
The process as in claim 1 wherein the volume resistivity of said different high molecular weight material is at least 1015 Omega - cm, and wherein the thickness of said base material varies from 50 to 3,000 microns and wherein the thickness of said different high molecular weight material coating varies from 8 to 100 microns.
Claim 3
Dependent Claim
9 words
The electret produced by the process of claim 1.
Claim 4
Dependent Claim
157 words
In a process for the production of an electret composed of a high molecular weight base material by applying to the base material a high D. C. potential at a high temperature, cooling the material while continuing the application of the potential, and then removing the electric potential, the improvement which comprises providing a stable electret by covering the opposite surfaces of the base material after polarizing the base material with thin films of a different high molecular weight material having a higher electrical insulating property than that of the base material prior th the application of the electric potential, said high molecular weight base material consisting essentially of polyvinylidene fluoride or a mixture of polyvinylidene fluoride with polymethyl methacrylate wherein the weight ratio of polyvinylidene fluoride to polymethyl methacrylate in said mixture is from six-fourths to seven-thirds, and wherein said different higher moleuclar weight material consists essentially of polytetrafluroethylene, polystyrene, polymethyl methacrylate, polyethylene terephthalate or polypropylene.
References Cited (Backward Citations)
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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) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |