US4845838A
Expired / Lapsed
US
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Method of making a PTC conductive polymer electrical device
Assignee: Tyco International Ltd Bermuda
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Filing: 1988-01-21
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Granted: 1989-07-11
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Expires: 2008-01-21
Abstract
Abstract Conductive polymer PTC compositions have improved properties, especially at voltages of 200 volts or more, if they are very highly cross-linked by means of irradiation. The radiation dosage may be, for example, a dosage of at least 50 Mrads, preferably at least 80 Mrads, e.g. 120 to 600 Mrads. The cross-linked compositions are particularly useful in circuit protection devices and layered heaters.
Inventors
- 👤 Stephen M. Jacobs
- 👤 Mary S. McTavish
- 👤 Frank A. Doljack
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:35
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/027; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082; Y10T29/49083
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
87 words
A process for the preparation of an electrical device comprising (a) a cross-linked PTC conductive polymer element and (b) two columnar electrodes which are embedded in the PTC element and which can be connected to a source of electrical power to cause current to flow through the PTC element, said process comprising melt-shaping a radiation cross-linkable PTC conductive polymer composition around the two columnar electrodes, and cross-linking the conductive polymer by irradiating substantially the whole of the PTC element to a dosage of at least 50 Mrads.
Claim 2
Dependent Claim
87 words
A process for the preparation of an electrical device comprising (a) a cross-linked PTC conductive polymer element and (b) two columnar electrodes which are embedded in the PTC element and which can be connected to a source of electrical power to cause current to flow through the PTC element, said process comprising melt-shaping a radiation cross-linkable PTC conductive polymer composition around the two columnar electrodes, and cross-linking the conductive polymer by irradiating substantially the whole of the PTC element to a dosage of at least 50 Mrads.
Claim 3
Dependent Claim
14 words
A process according to claim 1 wherein the dosage is at least 60 Mrads.
Claim 4
Dependent Claim
22 words
A process according to claim 1 wherein the PTC element is prepared by melt-extruding the conductive polymer composition around the columnar electrodes.
Claim 5
Dependent Claim
32 words
A process according to claim 3 wherein before the PTC element is irradiated, the extrudate is divided into discrete lengths and part of the conductive polymer is removed to expose both electrodes.
Claim 6
Dependent Claim
14 words
A process according to claim 1 wherein the dosage is at least 80 Mrads.
Claim 7
Dependent Claim
14 words
A process according to claim 1 wherein said dosage is at least 160 Mrads.
Claim 8
Dependent Claim
20 words
A process according to claim 1 wherein the PTC conductive polymer comprises a polymeric component having carbon black dispersed therein.
Claim 9
Dependent Claim
19 words
A process according to claim 7 wherein the carbon black is the sole particulate conductive filler in the composition.
Claim 10
Dependent Claim
18 words
A process according to claim 7 wherein the polymeric component consists essentially of one or more crystalline polymers.
Claim 11
Dependent Claim
13 words
A process according to claim 7 wherein the polymeric component comprises a polyolefin.
Claim 12
Dependent Claim
12 words
A process according to claim 7 wherein the polymeric component comprises polyethylene.
Claim 13
Dependent Claim
14 words
A process according to claim 7 wherein the polymeric component consists essentially of polyethylene.
Claim 14
Dependent Claim
23 words
A process according to claim 7 wherein the cross-linked PTC conductive polymer has a resistivity at 23° C. of less than 50 ohm.cm.
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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) | 1992-07-10 | 1993-01-09 | 1993-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-10 | 1997-01-09 | 1997-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-10 | 2001-01-09 | 2001-07-11 | $7700.00 | Window Closed / Lapsed |