Claims
- 1. A flexible heater which comprises
- (1) a support member which is in the form of a flat sheet; and
- (2) a heating element which is in the form of a tape, which has a ratio of external surface area to polymer volume of at least 20 inch.sup.-1, which is wrapped around the support member, and which comprises
- (a) a resistive element which is composed of a conductive polymer which comprises
- (i) particles of ultrahigh molecular weight polyethylene having a molecular weight of at least 3 million, which particles have been sintered without completely losing their identity, and
- (ii) a particulate conductive filler which is present substantially only at or near the boundaries of the coalesced particles; and
- (b) elongate electrodes which are secured to opposite margins of the resistive element and which can be connected to a source of electrical power to cause current to pass through the resistive element.
- 2. A heater according to claim 1 wherein the conductive filler is carbon black.
- 3. A heater according to claim 2 wherein the polyethylene has a molecular weight of 4 to 6 million.
- 4. A heater according to claim 3 wherein the conductive polymer has a resistivity of less than 100 ohm-cm.
- 5. A heater according to claim 2 wherein the resistive element has a ratio of width to thickness of at least 20.
- 6. A heater according to claim 5 wherein said ratio is 50 to 200.
- 7. A heater according to claim 6 wherein the resistive element is 0.005 to 0.05 inch thick and 1.0 to 1.5 inch wide.
- 8. A heater according to claim 1 wherein the ratio of the total surface area of the heating element to the volume of the tape is 40 to 100 inch.sup.-1.
- 9. A shaped article which comprises
- (1) a resilient foam of a polymeric material, and
- (2) at least partially embedded in the foam, a heating element which is in the form of a tape which has a ratio of external surface area to polymer volume of at least 20 inch.sup.-1 and which comprises
- (a) a resistive element which is composed of
- (i) particles of ultrahigh molecular weight polyethylene having a molecular weight of at least 3 million, which particles have been sintered without completely losing their identity, and
- (ii) a particulate conductive filler which is present substantially only at or near the boundaries of the coalesced particles; and
- (b) elongate electrodes which are secured to opposite margins of the resistive element and which can be connected to a source of electrical power to cause current to pass through the resistive element.
- 10. An upholstered seat which comprises a resilient seat member which is covered by a seat cover, a resilient back member which is covered by a back cover, and a flexible heater which lies between the resilient back member and the back cover, or between the resilient seat member and the seat cover, or both, the flexible heater comprising
- (1) a support member which is in the form of a flat sheet; and
- (2) a heating element which is in the form of a tape which has a ratio of external surface area to polymer volume of at least 20 inch.sup.-1, which is wrapped around the support member, and which comprises
- (a) a resistive element which is composed of
- (i) particles of ultrahigh molecular weight polyethylene having a molecular weight of at least 3 million, which particles have been sintered without completely losing their identity, and
- (ii) a particulate conductive filler which is present substantially only at or near the boundaries of the coalesced particles; and
- (b) elongate electrodes which are secured to opposite margins of the resistive element and which can be connected to a source of electrical power to cause current to pass through the resistive element.
- 11. A seat according to claim 10 wherein the heater lies only between the resilient back member and the back cover.
- 12. A seat according to claim 11 wherein the total surface area of the resistive element is 50 to 100 inch.sup.2.
- 13. A seat according to claim 10 wherein the back cover and the seat cover are made of leather.
- 14. A seat according to claim 10 which is in a wheeled vehicle and wherein the heater is switchably connected to the battery of the vehicle.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of copending, commonly assigned application Ser. No. 07/477,689, filed Feb. 9, 1990 now abandoned, the disclosure of which is incorporated herein by reference.
US Referenced Citations (11)
Foreign Referenced Citations (8)
Number |
Date |
Country |
2006165 |
Feb 1970 |
DEX |
2530937 |
Jan 1977 |
DEX |
272753A1 |
Oct 1989 |
DDX |
272754A1 |
Oct 1989 |
DDX |
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JPX |
WO8501482 |
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GBX |
Non-Patent Literature Citations (1)
Entry |
"Freeze-proof lines with electric tape", Power, vol. 91, p. 55, Oct., 1973 (New York). |
Continuations (1)
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Number |
Date |
Country |
Parent |
477689 |
Feb 1990 |
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