US4560498A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Positive temperature coefficient of resistance compositions
Assignee: Tyco International Ltd
•
Filing: 1979-10-12
•
Granted: 1985-12-24
•
Expires: 1999-10-12
Abstract
Abstract Disclosed is a positive temperature coefficient of resistance (PTC) crosslinked polymeric composition comprising a first polymeric material exhibiting high green strength prior to crosslinking and elastomeric behavior subsequent to cross-linking, and a second polymeric material comprising a thermoplastic, both said materials having dispersed therein conductive particles, e.g., carbon black, and further, said composition exhibiting a rise in resistance with increased temperature at temperatures above the melting point of either material.
Inventors
- 👤 David A. Horsma
- 👤 Teddy J. Hammack
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:39
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/027; C; C08; C08L; C08L101/00; H01B; H01B1/00; H01B1/20; H01B1/24; H01B3/00; H01B3/002; H01B3/004
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
127 words
An electrically conductive crosslinked polymeric composition which (a) is suitable for use in a self-regulating heating article comprising at least two electrodes positioned so that that, when the electrodes are connected to a power source, current passes through the composition, (b) has a positive temperature coefficient of resistance and (c) comprises (1) a first polymeric material which prior to cross-linking exhibits significant green strength corresponding to a tensile stress of at least 10 p.s.i. at 20% elongation and which exhibits elastomeric properties at ambient temperatures in the crosslinked state (2) a second thermoplastic polymeric material, and (3) conductive particles which have been dispersed in said polymeric material such that the composition exhibits increased resistance with increased temperatures at temperatures substantially above the melting point of either material.
Claim 2
Dependent Claim
127 words
An electrically conductive crosslinked polymeric composition which (a) is suitable for use in a self-regulating heating article comprising at least two electrodes positioned so that that, when the electrodes are connected to a power source, current passes through the composition, (b) has a positive temperature coefficient of resistance and (c) comprises (1) a first polymeric material which prior to cross-linking exhibits significant green strength corresponding to a tensile stress of at least 10 p.s.i. at 20% elongation and which exhibits elastomeric properties at ambient temperatures in the crosslinked state (2) a second thermoplastic polymeric material, and (3) conductive particles which have been dispersed in said polymeric material such that the composition exhibits increased resistance with increased temperatures at temperatures substantially above the melting point of either material.
Claim 3
Dependent Claim
12 words
The composition of claim 1 wherein the conductive particles are carbon black.
Claim 4
Dependent Claim
21 words
The composition of claim 1 wherein the elastomeric and thermoplastic materials are separate segments contained in a graft or block copolymer.
Claim 5
Dependent Claim
17 words
The composition of claim 1 wherein the elastomeric and thermoplastic materials comprise a physical blend of polymers.
Claim 6
Dependent Claim
12 words
The composition of claim 3 wherein the polymer is a graft copolymer.
Claim 7
Dependent Claim
12 words
The composition of claim 3 wherein the polymer is a block copolymer.
Claim 8
Dependent Claim
21 words
The composition of claim 5 wherein the elastomeric moiety is an ethylene-propylene rubber and the thermoplastic moiety is a crystalline polyolefin.
Claim 9
Dependent Claim
20 words
The composition of claim 6 wherein the elastomeric moiety is an ethylenepropylene rubber and the thermoplastic moiety is a polystyrene.
Claim 10
Dependent Claim
21 words
The composition of claim 6 wherein the elastomeric moiety is a polytetramethylene oxide and the thermoplastic moiety is a polytetramethylene terephthalate.
Claim 11
Dependent Claim
22 words
The composition of claim 4, wherein the elastomeric material is selected from the group consisting of chlorinated polyethylene, chlorosulfonated polyethylene and neoprene.
Claim 12
Dependent Claim
13 words
The composition of claim 4 comprising an ethylene-propylene rubber, polypropylene and carbon black.
Claim 13
Dependent Claim
37 words
The composition of claim 11 wherein the polypropylene is in the range of from 5 to 40% of the composition, the ethylene-propylene rubber is from 40 to 90% and the carbon black is from 5 to 35%.
Claim 14
Dependent Claim
31 words
The composition of claim 1 wherein the amount of the elastomeric material is from about 3 to about 75% by weight of the combined weight of elastomeric material and thermoplastic material.
Claim 15
Dependent Claim
27 words
The composition of claim 13 wherein the amount of the elastomeric material is from about 4 to about 40% by weight of elastomeric material and thermoplastic material.
Claim 16
Dependent Claim
22 words
The composition of claim 1 wherein the amount of the conductive material is from 4 to 60% by weight of the composition.
Claim 17
Dependent Claim
21 words
The composition of claim 15 wherein the amount of the conductive material is 5 to 50% by weight of the composition.
Claim 18
Dependent Claim
49 words
The composition of claim 1 wherein the amount of the elastomeric material is from about 4 to 40% by weight of the combined weight of the elastomeric material and the thermoplastic material, and the amount of the conductive filler is from 5 to 50% by weight of the composition.
Claim 19
Dependent Claim
16 words
The composition of claim 6 wherein the elastomeric region provides 30-70% by weight of the copolymer.
Claim 20
Dependent Claim
12 words
The composition of claim 1 which has been crosslinked by ionizing radiation.
Claim 21
Dependent Claim
13 words
The composition of claim 1 which has been annealed to obtain minimum resistance.
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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) | 1988-12-23 | 1989-06-24 | 1989-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-23 | 1993-06-24 | 1993-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-23 | 1997-06-24 | 1997-12-24 | $7700.00 | Window Closed / Lapsed |