US4951382A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making a PTC conductive polymer electrical device
Assignee: Tyco International Ltd Bermuda
•
Filing: 1988-01-21
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Granted: 1990-08-28
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Expires: 2008-01-21
Abstract
Abstract Conductive polymer PTC compositions have improved properties, especially at voltage of 200 volts or more, if they are very highly cross-linked by means of irradiation, for example to 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
2026-11-02 06:46
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: 19
Claim 1
Independent Claim
64 words
A process for the preparation of an electrical device comprising (a) a cross-linked PTC conductive polymer element and (b) two electrodes which can be connected to a source of electrical power to cause current to flow through the PTC element, said process comprising cross-linking the conductive polymer by irradiating substantially the whole of the PTC element to a dosage of at least 120 Mrads.
Claim 2
Dependent Claim
64 words
A process for the preparation of an electrical device comprising (a) a cross-linked PTC conductive polymer element and (b) two electrodes which can be connected to a source of electrical power to cause current to flow through the PTC element, said process comprising cross-linking the conductive polymer by irradiating substantially the whole of the PTC element to a dosage of at least 120 Mrads.
Claim 3
Dependent Claim
14 words
A process according to claim 1 wherein the dosage is at least 160 Mrads.
Claim 4
Dependent Claim
54 words
A process according to claim 1 which comprises (1) melt-extruding a radiation cross-linkable PTC conductive polymer composition to form a laminar PTC element which does not contain an electrode; (2) cross-linking the conductive polymer by irradiating substantially the whole of the PTC element; and (3) securing metal foil electrodes to the irradiated PTC element.
Claim 5
Dependent Claim
14 words
A process according to claim 3 wherein step (2) is conducted before step (3).
Claim 6
Dependent Claim
14 words
A process according to claim 3 wherein step (2) is conducted after step (3).
Claim 7
Dependent Claim
109 words
A process according to claim 1 which further comprises (1) melt-extruding a radiation cross-linkable PTC conductive polymer composition to form an extrudate which does not contain an electrode; (2) dividing the extrudate from step (1) into a plurality of discrete PTC elements, each PTC element being in the form of a strip with substantially planar parallel ends; and (3) securing to each end of the PTC element an electrode in the form of a cap having (i) a substantially planar end which contacts and has substantially the same cross-section as one end of the PTC element and (ii) a side wall which contacts the side of the PTC element.
Claim 8
Dependent Claim
15 words
A process according to claim 6 wherein the PTC element is irradiated before step (3).
Claim 9
Dependent Claim
15 words
A process according to claim 6 wherein the PTC element is irradiated after step (3).
Claim 10
Dependent Claim
62 words
A process according to claim 1 which further comprises (1) forming a laminar PTC element of a radiation cross-linkable conductive polymer composition; and (2) securing electrodes to the laminar PTC element, the electrodes being displaced from each other so that at least a substantial component of the current flow between the electrodes is along one of the large dimensions of the element.
Claim 11
Dependent Claim
18 words
A process according to claim 9 wherein step (2) is carried out before the PTC element is irradiated.
Claim 12
Dependent Claim
18 words
A process according to claim 9 wherein step (2) is carried out after the PTC element is irradiated.
Claim 13
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 14
Dependent Claim
19 words
A process according to claim 12 wherein the carbon black is the sole particulate conductive filler in the composition.
Claim 15
Dependent Claim
18 words
A process according to claim 12 wherein the polymeric component consists essentially of one or more crystalline polymers.
Claim 16
Dependent Claim
13 words
A process according to claim 12 wherein the polymeric component comprises a polyolefin.
Claim 17
Dependent Claim
12 words
A process according to claim 12 wherein the polymeric component comprises polyethylene.
Claim 18
Dependent Claim
14 words
A process according to claim 12 wherein the polymeric component consists essentially of polyethylene.
Claim 19
Dependent Claim
23 words
A process according to claim 12 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) | 1993-08-27 | 1994-02-26 | 1994-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-27 | 1998-02-26 | 1998-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-27 | 2002-02-26 | 2002-08-28 | $7700.00 | Window Closed / Lapsed |