US4304987A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical devices comprising conductive polymer compositions
Assignee: CDC/THE GOVERNMENT OF United States, HEALTH AND HUMAN SERVICES, Secretary of, Department of
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Filing: 1979-09-14
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Granted: 1981-12-08
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Expires: 1999-09-14
Abstract
Abstract Electrical devices which comprise a PTC element composed of a PTC conductive polymer composition and a contiguous CW element composed of a conductive polymer composition which comprises an organic thermoplastic polymer and a conductive carbon black having a particle size (D) in millimicrons and surface area (S) in m 2 /g such that S/D is at least 10. D is preferably less than 27 millimicrons, especially less than 18 millimicrons. S/D is preferably at least 12, especially at least 18. Particularly useful devices are in the form of heaters.
Inventors
- 👤 Peter H. van Konynenburg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:44
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/027
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
175 words
An electrical device comprising (a) A CW element composed of a CW composition which comprises (i) a continuous phase of a first crystalline organic thermoplastic polymer and (ii), dispersed in said first polymer, a first conductive carbon black having a particle size (D) which is less than 27 millimicrons and a surface area (S) in m 2 /g such that the ratio S/D is at least 12; (b) a PTC element composed of a PTC composition which comprises (i) a continuous phase of a second crystalline organic thermoplastic polymer and (ii), dispersed in said second polymer, a second conductive carbon black, said PTC element being electrically and structurally directly bonded to the CW element; and (c) at least two electrodes which are connectable to a source of electrical power and which are so placed in the device that, when they are connected to a source of electrical power, current flows between the electrodes through the device along a path which, at least at some temperatures, passes sequentially through said PTC element and said CW element.
Claim 2
Dependent Claim
175 words
An electrical device comprising (a) A CW element composed of a CW composition which comprises (i) a continuous phase of a first crystalline organic thermoplastic polymer and (ii), dispersed in said first polymer, a first conductive carbon black having a particle size (D) which is less than 27 millimicrons and a surface area (S) in m 2 /g such that the ratio S/D is at least 12; (b) a PTC element composed of a PTC composition which comprises (i) a continuous phase of a second crystalline organic thermoplastic polymer and (ii), dispersed in said second polymer, a second conductive carbon black, said PTC element being electrically and structurally directly bonded to the CW element; and (c) at least two electrodes which are connectable to a source of electrical power and which are so placed in the device that, when they are connected to a source of electrical power, current flows between the electrodes through the device along a path which, at least at some temperatures, passes sequentially through said PTC element and said CW element.
Claim 3
Dependent Claim
45 words
A device according to claim 1 wherein the CW composition contains 6 to 40% by weight of the first carbon black and has been prepared by a process which comprises mixing the first carbon black with the first polymer while the first polymer is molten.
Claim 4
Dependent Claim
18 words
A device according to claim 1 wherein the first carbon black has a particle size below 18 millimicrons.
Claim 5
Dependent Claim
31 words
A device according to claim 3 wherein the first carbon black has a particle size of at most 15 millimicrons and a surface area of at least 300 m 2 /g.
Claim 6
Dependent Claim
22 words
A device according to claim 3 wherein the first carbon black has a surface area of at least 500 m 2 /g.
Claim 7
Dependent Claim
14 words
A device according to claim 1 wherein the ratio S/D is at least 18.
Claim 8
Dependent Claim
52 words
A device according to claim 1 wherein the ratio of the maximum resistivity of said CW composition in the temperature range from 25° C. to a temperature 40° C. below the melting point of said first organic polymer to the resistivity of said CW composition at 25° C. is less than 2.
Claim 9
Dependent Claim
47 words
A device according to claim 7 wherein the ratio of the maximum resistivity of said CW composition in the temperature range from 25° C. to the melting point of said first organic polymer to the resistivity of said CW composition at 25° C. is less than 5.
Claim 10
Dependent Claim
14 words
A device according to claim 1 wherein the CW and PTC compositions are cross-linked.
Claim 11
Dependent Claim
22 words
A device according to claim 1 wherein the resistivity of the CW composition at 25° C. is from 1,000 to 10,000 ohm.cm.
Claim 12
Dependent Claim
28 words
A device according to claim 1 wherein the resistivity of the CW composition at 25° C. is more than the resistivity of the PTC composition at 25° C.
Claim 13
Dependent Claim
36 words
A device according to claim 1 wherein the first polymer has a melting point T 1 and the second polymer has a melting point T 2 which is from (T 1 -25) to (T 1 +25)°C.
Claim 14
Dependent Claim
47 words
A device according to claim 1 wherein the first polymer is a copolymer consisting essentially of units derived from at least one olefin and at least 10% by weight of at least one olefinically unsaturated comonomer containing a polar group and the second polymer is a polyolefin.
Claim 15
Dependent Claim
30 words
A device according to claim 13 wherein the first polymer is a copolymer of ethylene and vinyl acetate or an acrylic ester and the second polymer is polyethylene or polypropylene.
Claim 16
Dependent Claim
23 words
A device according to claim 1 wherein the first and second polymers each contain at least 50% by weight of vinylidene fluoride units.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-07 | 1985-06-08 | 1985-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-07 | 1989-06-08 | 1989-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-07 | 1993-06-08 | 1993-12-08 | $7700.00 | Window Closed / Lapsed |