Patent US4907340A successfully refreshed from Google Patents.
US4907340A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical device comprising conductive polymers
Assignee: Tyco International Ltd Bermuda
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Filing: 1987-09-30
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Granted: 1990-03-13
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Expires: 2007-09-30
Abstract
Abstract A process for preparing an electrical device which comprises a conductive polymer exhibiting PTC behavior. The device is irradiated by use of an electron beam at an average dose rate of less than 3.0 Mrad/minute. The cross-linking may be to a level of 50 to 100 Mrad or higher for devices designed to withstand high voltage test conditions. The device may be a laminar device comprising a center layer of higher resistivity than two surrounding layers.
Inventors
- 👤 Shou-Mean Fang
- 👤 Charles H. Camphouse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:59
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/027; H01C7/021; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
107 words
A process for the preparation of an electrical device which comprises (1) a PTC element composed of a cross-linked conductive polymer composition which exhibits PTC behavior and which comprises a polymeric component and, dispersed in the polymeric component, a particulate conductive filler; and (2) two electrodes which are electrically connected to the PTC element and which are connectable to a source of electrical power to cause current to pass through the PTC element, which process comprises subjecting the PTC element to radiation cross-linking in which (i) said cross-linking is achieved by use of an electron beam and (ii) the average dose rate is at most 3.0 Mrad/minute.
Claim 2
Dependent Claim
107 words
A process for the preparation of an electrical device which comprises (1) a PTC element composed of a cross-linked conductive polymer composition which exhibits PTC behavior and which comprises a polymeric component and, dispersed in the polymeric component, a particulate conductive filler; and (2) two electrodes which are electrically connected to the PTC element and which are connectable to a source of electrical power to cause current to pass through the PTC element, which process comprises subjecting the PTC element to radiation cross-linking in which (i) said cross-linking is achieved by use of an electron beam and (ii) the average dose rate is at most 3.0 Mrad/minute.
Claim 3
Dependent Claim
19 words
A process according to claim 1 wherein said cross-linking is conducted to a dose of at least 50 Mrad.
Claim 4
Dependent Claim
19 words
A process according to claim 1 wherein said cross-linking is conducted to a dose of at least 100 Mrad.
Claim 5
Dependent Claim
47 words
A process according to claim 1 wherein said cross-linking is conducted in two steps, said steps being separated by a heat-treatment process wherein said PTC element is heated to a temperature above the melting temperature of the polymeric component and is then cooled to recrystallize the polymer.
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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) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |