Patent US2078094A successfully refreshed from Google Patents.
Patent US4775778A successfully refreshed from Google Patents.
US4775778A
Expired / Lapsed
US
⏱️ 0.0 years remaining
PTC compositions and devices comprising them
Assignee: Tyco International Ltd Bermuda
•
Filing: 1985-05-14
•
Granted: 1988-10-04
•
Expires: 2005-05-14
Abstract
Abstract Novel conductive polymer compositions which exhibit useful PTC behavior are produced by cross-linking processes. By correlating the polymer, the conductive filler dispersed therein, and the cross-linking conditions, PTC compositions having desired resistance/temperature characteristics can be prepared. In particular the cross-linking can be carried out so as to provide compositions having a switching temperature around the cross-linking temperature. The invention is applicable to both elastomeric and thermoplastic polymers, and provides for the first time a method of making PTC compositions exhibiting useful PTC behavior from elastomers.
Inventors
- 👤 Peter H. van Konynenburg
- 👤 Bernard J. Lyons
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:04
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/40; H05B3/54; H05B3/56; C; C08; C08K; C08K3/00; C08K3/02; C08K3/04; H01; H01B; H01B1/00; H01B1/20; H01B1/24; H01C; H01C7/00; H01C7/02; H01C7/027; H05B3/10; H05B3/12; H05B3/14; H05B3/146; H05B3/565
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
131 words
An electrical device which comprises two or more electrodes and a PTC composition in contact therewith, the PTC composition comprising: (1) a cross-linked elastomer prepared by cross-linking an elastomeric gum having a tensile stress of less than 10 psi at 20% elongation; and (2) conductive particles enclosed with the cross-linked network of said elastomer, the particles having a size of at least 18 millimicrons: which composition (a) has a gel fraction of at least 0.6; (b) exhibits PTC behavior with an R 14 value of at least 2.5 or an R 100 value of at least 10, and at least one T s within the temperature range from room temperature to +250° C.; and (c) has a volume resistivity at temperatures below said T s between 25 and 10 5 ohm.cm.
Claim 2
Dependent Claim
131 words
An electrical device which comprises two or more electrodes and a PTC composition in contact therewith, the PTC composition comprising: (1) a cross-linked elastomer prepared by cross-linking an elastomeric gum having a tensile stress of less than 10 psi at 20% elongation; and (2) conductive particles enclosed with the cross-linked network of said elastomer, the particles having a size of at least 18 millimicrons: which composition (a) has a gel fraction of at least 0.6; (b) exhibits PTC behavior with an R 14 value of at least 2.5 or an R 100 value of at least 10, and at least one T s within the temperature range from room temperature to +250° C.; and (c) has a volume resistivity at temperatures below said T s between 25 and 10 5 ohm.cm.
Claim 3
Dependent Claim
20 words
A device according to claim 1 wherein the elastomer has been crosslinked with the aid of a chemical cross-linking agent.
Claim 4
Dependent Claim
56 words
A device according to claim 1 wherein the PTC composition is one whose T s remains substantially unchanged when repeatedly subjected to thermal cycling which comprises heating the composition from a temperature below T s to a temperature above T s but below the peak temperature, followed by cooling to a temperature below T s .
Claim 5
Dependent Claim
22 words
A device according to claim 1 wherein the conductive particles are carbon black particles having a size of 22 to 80 millimicrons.
Claim 6
Dependent Claim
12 words
A device ccording to claim 1 wherein the elastomer is a polysiloxane.
Claim 7
Dependent Claim
18 words
A device according to claim 5 wherein the PTC composition comprises a polysiloxane having silica particles dispersed therein.
Claim 8
Dependent Claim
38 words
A device according to claim 5 which is a strip heater comprising an elongate element of said PTC composition, two longitudinally extending, parallel electrodes embedded in said composition, and an outer layer of a protective and insulating composition.
Claim 9
Dependent Claim
115 words
A PTC composition comprising: (1) a cross-linked elastomer prepared by cross-linking an elastomeric gum having a tensile stress of less than 10 psi at 20% elongation; and (2) conductive particles enclosed within the cross-linked network of said elastomer, the particles having a size of at least 18 millimicrons; which composition (a) has a gel fraction of at least 0.6; (b) exhibits PTC behavior with an R 14 value of at least 2.5 or an R 100 value of at least 10, and at least one T s within the temperature range from room temperature to +250° C.; and (c) has a volume resistivity at temperatures below said T s between 25 and 10 5 ohm.cm.
Claim 10
Dependent Claim
115 words
A PTC composition comprising: (1) a cross-linked elastomer prepared by cross-linking an elastomeric gum having a tensile stress of less than 10 psi at 20% elongation; and (2) conductive particles enclosed within the cross-linked network of said elastomer, the particles having a size of at least 18 millimicrons; which composition (a) has a gel fraction of at least 0.6; (b) exhibits PTC behavior with an R 14 value of at least 2.5 or an R 100 value of at least 10, and at least one T s within the temperature range from room temperature to +250° C.; and (c) has a volume resistivity at temperatures below said T s between 25 and 10 5 ohm.cm.
Claim 11
Dependent Claim
21 words
A PTC composition according to claim 8 wherein the elastomer has been cross-linked with the aid of a chemical cross-linking agent.
Claim 12
Dependent Claim
19 words
A PTC composition according to claim 9 wherein the elastomer has been cross-linked with the aid of a peroxide.
Claim 13
Dependent Claim
51 words
A PTC composition according to claim 1 whose T s remains substantially unchanged when repeatedly subjected to thermal cycling which comprises heating the composition from a temperature below T s to a temperature above T s but below the peak temperature, followed by cooling to a temperature below T s .
Claim 14
Dependent Claim
23 words
A PTC composition according to claim 1 wherein the conductive particles are carbon black particles having a size of 22 to 80 millimicrons.
Claim 15
Dependent Claim
20 words
A PTC composition according to claim 8 which further comprises non-conductive particles enclosed within the cross-linked network of the elastomer.
Claim 16
Dependent Claim
19 words
A PTC composition according to claim 13 wherein the polymer is a polysiloxane and the non-conductive filler is silica.
Claim 17
Dependent Claim
13 words
A PTC composition according to claim 8 wherein the elastomer is a polysiloxane.
Claim 18
Dependent Claim
19 words
A PTC composition according to claim 15 wherein the conductive particles consist essentially of at least one carbon black.
Claim 19
Dependent Claim
143 words
A process for the preparation of a PTC composition which comprises: (1) dispersing conductive particles having a size of at least 18 millimicrons in an elastomeric gum having a tensile stress of less than 10 psi at 20% elongation; and (2) cross-linking the dispersion from step (1) to obtain a composition which has a gel fraction of at least 0.6 and which comprises conductive particles enclosed with the elastomer resulting from said cross-linking; the particles, the elastomeric gum, and the cross-linking conditions being such that the cross-linked composition (a) exhibits PTC behavior with an R 14 value of at least 2.5 or an R 100 value of at least 10, and at least one T s within the temperature range from room temperature to +250° C.; and (b) has a volume resistivity at temperatures below T s between 25 and 10 5 ohm.cm.
Claim 20
Dependent Claim
143 words
A process for the preparation of a PTC composition which comprises: (1) dispersing conductive particles having a size of at least 18 millimicrons in an elastomeric gum having a tensile stress of less than 10 psi at 20% elongation; and (2) cross-linking the dispersion from step (1) to obtain a composition which has a gel fraction of at least 0.6 and which comprises conductive particles enclosed with the elastomer resulting from said cross-linking; the particles, the elastomeric gum, and the cross-linking conditions being such that the cross-linked composition (a) exhibits PTC behavior with an R 14 value of at least 2.5 or an R 100 value of at least 10, and at least one T s within the temperature range from room temperature to +250° C.; and (b) has a volume resistivity at temperatures below T s between 25 and 10 5 ohm.cm.
Claim 21
Dependent Claim
13 words
A process according to claim 17 wherein the conductive particles comprise carbon black.
Claim 22
Dependent Claim
12 words
A process according to claim 17 wherein the elastomer is a polysiloxane.
Claim 23
Dependent Claim
14 words
A process according to claim 19 wherein the polysiloxane contain silica as a filler.
Claim 24
Dependent Claim
18 words
A process according to claim 19 wherein the conductive particles consist essentially of one or more carbon blacks.
Claim 25
Dependent Claim
14 words
A process according to claim 17 wherein the elastomeric gum is cross-linked by irradiation.
Claim 26
Dependent Claim
20 words
A process according to claim 17 wherein the elastomeric gum is cross-linked with the aid of a chemical cross-linking agent.
Claim 27
Dependent Claim
31 words
A process according to claim 17 wherein the cross-linking temperature is above 20° C. and the conductive filler is a carbon black having a particle size of at least 20 millimicrons.
Claim 28
Dependent Claim
31 words
A process according to claim 17 wherein the cross-linking temperature is above 100° C. and the conductive filler is a carbon black having a particle size of at least 30 millimicrons.
Claim 29
Dependent Claim
31 words
A process according to claim 17 wherein the cross-linking temperature is above 150° C. and the conductive filler is a carbon black having a particle size of at least 40 millimicrons.
References Cited (Backward Citations)
US2763609A
Cited
US3412358A
Cited
US3547834A
Cited
US3658750A
Cited
US3689618A
Cited
US3757088A
Cited
US3914363A
Cited
US3929718A
Cited
US4062813A
Cited
JPS50151251A
Cited
JPS5139742A
Cited
JPS5139743A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-04 | 1992-04-04 | 1992-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-04 | 1996-04-04 | 1996-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-04 | 2000-04-04 | 2000-10-04 | $7700.00 | Window Closed / Lapsed |