Claims
- 1. An electrical device which comprises
- (A) an element composed of a conductive polymer composition which comprises
- (1) a polymeric component which comprises
- (a) a first polymer which (i) is present in an amount 25 to 75% by weight of the total polymeric component, and (ii) is polyethylene, and
- (b) a second polymer which (i) is present in an amount 25 to 75% by weight of the total polymeric component, and (ii) comprises units derived from a first monomer which is ethylene and a second monomer which is an alkyl acrylate having the formula CH.sub.2 .dbd.CHCOOC.sub.m H.sub.2m+1, where m is at least 4; and
- (2) a particulate conductive filler which is dispersed in the polymeric component; and
- (B) at least one electrode which is suitable for connecting the conductive polymer element to a source of electrical power.
- 2. A device according to claim 1 which comprises two electrodes.
- 3. A device according to claim 1 wherein the element is in the form of a laminar element and the electrode comprises a metal foil.
- 4. A device according to claim 1 wherein the first polymer is high density polyethylene.
- 5. A device according to claim 1 wherein m is at most 8.
- 6. A device according to claim 1 wherein the second monomer is butyl acrylate.
- 7. A device according to claim 1 wherein the conductive polymer composition exhibits PTC behavior.
- 8. A device according to claim 1 wherein the conductive filler is carbon black.
- 9. A device according to claim 1 wherein the composition comprises 35 to 75% of the polymeric component and 25 to 65% by weight of the conductive filler.
- 10. A device according to claim 1 which has a resistance of less than 100 ohms.
- 11. A device according to claim 10 which has a resistance of less than 10 ohms.
- 12. A device according to claim 11 which has a resistance of less than 1 ohm.
- 13. A device according to claim 1 wherein the composition has a resistivity at 20.degree. C., .rho..sub.20, of less than 10 ohm-cm.
- 14. A device according to claim 1 which has a trip current I.sub.T at 80.degree. C. of less than 2A.
- 15. A device according to claim 1 which has a hold current I.sub.H at 60.degree. C. of at least 1A.
- 16. A device according to claim 1 wherein the ratio of trip current I.sub.T at 80.degree. C. to hold current I.sub.H at 60.degree. C. is at most 1.3.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional application of copending, commonly assigned application Ser. No. 08/255,497, allowed, filed Jun. 8, 1994, the disclosure of which is incorporated herein by reference.
US Referenced Citations (36)
Foreign Referenced Citations (1)
Number |
Date |
Country |
WO9401876 |
Jul 1983 |
WOX |
Divisions (1)
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Number |
Date |
Country |
Parent |
255497 |
Jun 1994 |
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