US4668857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature self-regulating resistive heating element
Assignee: Belton Corp
•
Filing: 1985-08-16
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Granted: 1987-05-26
•
Expires: 2005-08-16
Abstract
Abstract Disclosed is an improved temperature self-regulating resistive heating element and a method for its fabrication. The element utilizes a positive temperature coefficient (PTC) composition comprising a blend of two partially incompatible crystalline polymers of differing melting points and an electrically conductive filler. The PTC composition does not deform during annealing, this permitting the fabrication of temperature self-regulating resistive heating element with electrodes spaced-apart by not more than 0.100 inch. Heating elements provided by the invention have a smaller cross section, are more flexible, and are less expensive to fabricate than similar prior art elements.
Inventors
- 👤 Jack H. Smuckler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:26
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/027
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
74 words
A temperature self-regulating resistive heating element comprising: A. first and second conductive electrodes spaced-apart by not more than 0.100 inch; and B. a PTC composition disposed between, and in electrical communication with, said conductive electrodes, said PTC composition comprising a mixture of a first crystalline polymer, a second crystalline polymer, and a conductive filler material, said first and second polymers being at least partially incompatible and having melting point at least 20° F. apart.
Claim 2
Dependent Claim
74 words
A temperature self-regulating resistive heating element comprising: A. first and second conductive electrodes spaced-apart by not more than 0.100 inch; and B. a PTC composition disposed between, and in electrical communication with, said conductive electrodes, said PTC composition comprising a mixture of a first crystalline polymer, a second crystalline polymer, and a conductive filler material, said first and second polymers being at least partially incompatible and having melting point at least 20° F. apart.
Claim 3
Dependent Claim
18 words
The heating element of claim 1 wherein said first and second polymers are of at least 20% crystallinity.
Claim 4
Dependent Claim
25 words
The heating element of claim 1 wherein the melting point of said second polymer is at least 50° F. above that of said first polymer.
Claim 5
Dependent Claim
14 words
The heating element of claim 1 wherein said conductive filler material includes carbon black.
Claim 6
Dependent Claim
22 words
The heating element of claim 4 where said conductive carbon black comprises not more than 25% by weight of said PTC composition.
Claim 7
Dependent Claim
27 words
The heating element of claim 1 wherein said first and second polymers are selected from a group consisting of polyolefins, fluorocarbon polymers, and terpolymers containing non-conjugated dienes.
Claim 8
Dependent Claim
21 words
The heating element of claim 1 wherein said first polymer is a polyolefin and said second polymer is a halogenated polyolefin.
Claim 9
Dependent Claim
37 words
The heating element of claim 1 wherein said first polymer is low density polyethylene and said second polymer is selected from the group consisting of polytetrafluoroethylene, fluorinated copolymers of ethylene/propylene, polychlorotrifluoroethylene, poly (ethylene-chlorotrifluoroethylene), fluorinated polyvinylidene, and polypropylene.
Claim 10
Dependent Claim
32 words
The heating element of claim 8 wherein said first polymer is polypropylene and said second polymer is selected from the group consisting of polytetrafluoroethylene, fluorinated copolymers of ethylene/propylene, polychlorotrifluoroethylene, and poly (ethylene-chlorotrifluoroethylene).
Claim 11
Dependent Claim
36 words
The heating element of claim 8 wherein said first polymer is low density polyethylene and said second polymer is selected from the group consisting of fluorinated polyvinylidene, fluorinated copolymers of ethylene/propylene, chlorotrifluoroethylene, poly (ethylene-chlorotrifluoroethylene), and polypropylene.
Claim 12
Dependent Claim
38 words
The heating element of claim 1 comprising an electrically conductive film disposed between said PTC composition and one of said conductive electrodes, said film being in electrical communication with said one conductive electrode and with said PTC composition.
Claim 13
Dependent Claim
20 words
The heating element of claim 11 wherein said conductive film has a melting point above that of both said polymers.
Claim 14
Dependent Claim
21 words
The heating element of claim 11 wherein said conductive film comprises a polymer containing less than 40% by weight carbon black.
Claim 15
Dependent Claim
25 words
The heating element of claim 1 further comprising an insulating material disposed about the combined said first electrode, said second electrode, and said PTC composition.
Claim 16
Dependent Claim
29 words
The heating element of claim 1 wherein said first electrode is disposed axially within an elongate PTC composition and said second electrode is wound about said elongate PTC composition.
Claim 17
Dependent Claim
34 words
The heating element of claim 15 further comprising an electrically conductive film disposed between said PTC composition and said wound second electrode and in electrical communication with said PTC composition and said second electrode.
Claim 18
Dependent Claim
20 words
The heating element of claim 15 further comprising an insulating material disposed about said second electrode and said PTC composition.
Claim 19
Dependent Claim
15 words
The heating element of claim 1 wherein said electrodes are substantially parallel to each other.
References Cited (Backward Citations)
US3243753A
Cited
US3413442A
Cited
US3338476A
Cited
US3410984A
Cited
US3435401A
Cited
US3733385A
Cited
US3673121A
Cited
US3976600A
Cited
US3836482A
Cited
US3861029A
Cited
US3914363A
Cited
US3858144A
Cited
US3823217A
Cited
US4334148A
Cited
US4330703A
Cited
US4150193A
Cited
US4314145A
Cited
US4237441A
Cited
US4350652A
Cited
US4277673A
Cited
US4543474A
Cited
US4334351A
Cited
US4318881A
Cited
US4309597A
Cited
US4400614A
Cited
US4271350A
Cited
US4400250A
Cited
US4459473A
Cited
US4560524A
Cited
US4520260A
Cited
US4503322A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-25 | 1990-11-24 | 1991-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-25 | 1994-11-24 | 1995-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-25 | 1998-11-24 | 1999-05-26 | $7700.00 | Window Closed / Lapsed |