US4259398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical insulating material
Assignee: Mitsubishi Paper Mills Ltd
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Filing: 1979-07-23
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Granted: 1981-03-31
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Expires: 1999-07-23
Abstract
Abstract An electrical insulating material composed of a mica flake layer and a heat resistant base material layer is prepared by superposing the mica flake sheet containing at most 9% by weight of pulp-like particles of a heat resistant polymer based thereon on the heat resistant base material sheet, both of which sheets being dried, and heating them under pressure. The electrical insulating material has excellent in structural strength, varnish-impregnability, and is resist to pealing off of the mica flakes.
Inventors
- 👤 Shunji Seino
- 👤 Ryota Nishiyama
- 👤 Masaoki Nozaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:50
CPC Classifications
B; B32; B32B; B32B19/00; B32B19/02; B32B19/04; B32B19/045; H; H01; H01B; H01B3/00; H01B3/02; H01B3/04; B32B2262/00; B32B2262/10; B32B2307/00; B32B2307/20; B32B2307/206; B32B2307/30; B32B2307/306; B32B2315/00; B32B2315/10; Y; Y10; Y10T; Y10T428/00; Y10T428/25; Y10T428/251; Y10T428/29; Y10T428/2904; Y10T428/2982; Y10T442/00; Y10T442/60; Y10T442/608; Y10T442/696; Y10T442/699
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
102 words
A process for producing an electrical insulating material comprising superposing a dried sheet of a mixture of at least 91 parts by weight of tiny mica flakes and at most 9 parts by weight of pulp-like particles of a heat resistant polymer selected from the group consisting of an aromatic polyamide and an aromatic polyamide-imide on at least one side of a dried sheet of a heat resistant base material containing the heat resistant polymer, which has sufficient structural strength and bonding them by heating at a temperature of 150° to 330° C. under a linear pressure of 50 to 300 kg/cm.
Claim 2
Dependent Claim
102 words
A process for producing an electrical insulating material comprising superposing a dried sheet of a mixture of at least 91 parts by weight of tiny mica flakes and at most 9 parts by weight of pulp-like particles of a heat resistant polymer selected from the group consisting of an aromatic polyamide and an aromatic polyamide-imide on at least one side of a dried sheet of a heat resistant base material containing the heat resistant polymer, which has sufficient structural strength and bonding them by heating at a temperature of 150° to 330° C. under a linear pressure of 50 to 300 kg/cm.
Claim 3
Dependent Claim
12 words
An electrical insulating material produced by the process according to claim 1.
Claim 4
Dependent Claim
35 words
A process according to claim 1, wherein the heat resistant base material contains pulp-like particles of the heat resistant polymer or a mixture of the pulp-like particles with short fibers of the heat resistant polymer.
Claim 5
Dependent Claim
16 words
A process according to claim 3, wherein the heat resistant base material contains further inorganic fibers.
Claim 6
Dependent Claim
22 words
A process according to claim 1, wherein the temperature of said heating is near the softening temperature of said heat resistant polymer.
Claim 7
Dependent Claim
12 words
An electrical insulating material produced by the process according to claim 3.
Claim 8
Dependent Claim
12 words
An electrical insulating material produced by the process according to claim 4.
Claim 9
Dependent Claim
12 words
An electrical insulating material produced by the process according to claim 5.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-30 | 1984-09-29 | 1985-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-30 | 1988-09-29 | 1989-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-30 | 1992-09-29 | 1993-03-31 | $7700.00 | Window Closed / Lapsed |