US4818439A
Expired / Lapsed
US
⏱️ 0.0 years remaining
PTC compositions containing low molecular weight polymer molecules for reduced annealing
Assignee: Sunbeam Products Inc
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Filing: 1986-01-30
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Granted: 1989-04-04
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Expires: 2006-01-30
Abstract
Abstract A revolutionary new semiconductive material having a sharp rise in electrical resistance at a predetermined maximum temperature with substantially no annealing necessary after extrusion to achieve an essentially constant resistance at room temperature. The PTC composition includes a finely divided conductive material, such as carbon black; a suitable semicrystalline polymer having a molecular weight distribution containing a sufficient number of relatively low molecular weight molecules to substantially eliminate annealing; and a suitable polymeric material providing a sufficient number of polar molecules for electrical conductivity. At least 9% by weight of the polymer molecules should be in the molecular weight range of 1,000 to 30,000, and particularly in the 5,000 to 23,000 range and the entire polymeric portion of the composite composition should have a number average molecular weight of 30,000 or less. Generally, the relatively low molecular weight molecules of the semicrystalline polymer (1,000 to 30,000 and particularly 5,000 to 23,000 M.S.) are included in an amount of 9% to 15% based on the total weight of polymer molecules in the composition.
Inventors
- 👤 Brian D. Blackledge
- 👤 William M. Rowe, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:49
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/40; H05B3/54; H05B3/56; H01; H01C; H01C7/00; H01C7/02; H01C7/027
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
66 words
An electrically conductive composite polymer material comprising a suitable finely divided electrically conductive carbon black in an amount of 4 to 25% by weight dispersed within an olefinic polymer wherein the polymer has a number average molecular weight in the range of about 15,000 to 40,000 to reduce the annealing time necessary to achieve an electrically conductive material exhibiting PTC behavior to less than one minute.
Claim 2
Dependent Claim
66 words
An electrically conductive composite polymer material comprising a suitable finely divided electrically conductive carbon black in an amount of 4 to 25% by weight dispersed within an olefinic polymer wherein the polymer has a number average molecular weight in the range of about 15,000 to 40,000 to reduce the annealing time necessary to achieve an electrically conductive material exhibiting PTC behavior to less than one minute.
Claim 3
Dependent Claim
22 words
The composite polymer material of claim 1 wherein the carbon black comprises a carbon black having a pH of at least 4.0.
Claim 4
Dependent Claim
19 words
The material of claim 2 wherein the carbon black has a pH in the range of 5.0 to 8.5.
Claim 5
Dependent Claim
19 words
The material of claim 3 wherein the carbon black has a pH in the range of 5.5 to 8.0.
Claim 6
Dependent Claim
30 words
The composite polymer material of claim 2 wherein the carbon black has a dry volatile content, when heated to 950° C. of less than or equal to 3.0% by weight.
Claim 7
Dependent Claim
35 words
The composite polymer material of claim 1 wherein the carbon black has a N 2 surface area A in m 2 /gram and a DBP absorption x in cc/100 grams such that A≧1.75x+e x/37 .
Claim 8
Dependent Claim
51 words
The composite polymer material of claim 6 wherein the polymer has a number average molecular weight of 15,000 to 40,000 and a sufficient number of molecules in the molecular weight range of 1,000 to 30,000, as measured by gel permeation chromatographic analysis, to essentially eliminate the need for annealing after extrusion.
Claim 9
Dependent Claim
35 words
The composite polymer material of claim 7 wherein the polymer includes a sufficient number of low molecular weight molecules to require annealing for less than 1 second before achieving an essentially constant room temperature conductivity.
Claim 10
Dependent Claim
23 words
The composite polymer material of claim 1 wherein the polymer has a number average molecular weight in the range of 15,000 to 30,000.
Claim 11
Dependent Claim
23 words
The composite polymer material of claim 1 wherein the polymer has a number average molecular weight in the range of 20,000 to 25,000.
Claim 12
Dependent Claim
22 words
The composite polymer material of claim 9 wherein the carbon black comprises a carbon black having a pH of at least 4.0.
Claim 13
Dependent Claim
35 words
The composite polymer material of claim 11 wherein the carbon black has a N 2 surface area A in m 2 /gram and a DBP absorption x in cc/100 grams such that A≧1.75x+e x/37 .
Claim 14
Dependent Claim
48 words
The composite polymer material of claim 1 wherein the olefinic polymer has a weight average molecular weight of about 200,000 or less; a number average molecular weight of about 15,000 to 30,000; and 9 to 15% of the polymer molecules having a molecular weight of less than 23,000.
Claim 15
Dependent Claim
67 words
An electrically conductive composite polymer material comprising a suitable finely divided electrically conductive carbon black in an amount of 4 to 25% by weight dispersed within an olefinic polymer wherein the polymer has a number average molecular weight in the range of about 15,000 to about 40,000 to reduce the annealing time necessary to achieve an electrically conductive material exhibiting PTC behavior to less than one minute.
Claim 16
Dependent Claim
67 words
An electrically conductive composite polymer material comprising a suitable finely divided electrically conductive carbon black in an amount of 4 to 25% by weight dispersed within an olefinic polymer wherein the polymer has a number average molecular weight in the range of about 15,000 to about 40,000 to reduce the annealing time necessary to achieve an electrically conductive material exhibiting PTC behavior to less than one minute.
Claim 17
Dependent Claim
88 words
An electrically conductive composite polymer material comprising a suitable finely divided electrically conductive carbon black in an amount of 4 to 25% by weight dispersed within a first, semicrystalline, olefinic polymer wherein the polymer has a number average molecular weight in the range of about 15,000 to 40,000; and a second polymer material having one or more polar groups in an amount of at least 2% by weight of the electrically conductive material to reduce the annealing time necessary to achieve an electrically conductive material exhibiting PTC behavior.
Claim 18
Dependent Claim
88 words
An electrically conductive composite polymer material comprising a suitable finely divided electrically conductive carbon black in an amount of 4 to 25% by weight dispersed within a first, semicrystalline, olefinic polymer wherein the polymer has a number average molecular weight in the range of about 15,000 to 40,000; and a second polymer material having one or more polar groups in an amount of at least 2% by weight of the electrically conductive material to reduce the annealing time necessary to achieve an electrically conductive material exhibiting PTC behavior.
References Cited (Backward Citations)
US4560524A
Cited
US4668857A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-03 | 1992-10-03 | 1993-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-03 | 1996-10-03 | 1997-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-03 | 2000-10-03 | 2001-04-04 | $7700.00 | Window Closed / Lapsed |