US4237441A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low resistivity PTC compositions
Assignee: Littelfuse Inc
•
Filing: 1978-12-01
•
Granted: 1980-12-02
•
Expires: 1998-12-01
Abstract
Abstract Compositions which exhibit PTC behavior with a switching temperature (T s ) above 0° C., which have a resistivity at a temperature below T s of less than 7 ohm. cm, and which comprise a crystalline polymer and a particulate filler component which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area S in m 2 /gram such that S/D is not more than 10. The composition preferably has a peak resistivity of at least 1000 ohm. cm and is electrically stable when aged at elevated temperature. The quantity ##EQU1## is preferably less than 1, especially less than 0.5. Shaped articles of such compositions are prepared by a process in which the carbon black is dispersed in the molten polymer and the dispersion is then melt-shaped, the total energy used in preparing and melt-shaping the dispersion being 1 to 300 hp. hr. ft -3 , preferably 1 to 100 hp. hr. ft -3 , especially 1 to 50 hp. hr. ft -3 . The compositions are particularly useful in circuit protection devices.
Inventors
- 👤 Peter V. van Konynenburg
- 👤 Andrew Au
- 👤 Chris Rauwendaal
- 👤 Alan J. Gotcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:55
CPC Classifications
C; C08; C08K; C08K3/00; C08K3/02; C08K3/04; H; H01; H01B; H01B1/00; H01B1/20; H01B1/24; H01C; H01C7/00; H01C7/02; H01C7/027; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082
Claims Analysis
Total Claims: 50
Claim 1
Independent Claim
114 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C.; and which comprises (1) a polymer component having at least 10% crystallinity and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /gram such that S/D is not more than 10; the amount of said filler component being such that the quantity ##EQU7## is less than 1.
Claim 2
Dependent Claim
114 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C.; and which comprises (1) a polymer component having at least 10% crystallinity and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /gram such that S/D is not more than 10; the amount of said filler component being such that the quantity ##EQU7## is less than 1.
Claim 3
Dependent Claim
17 words
A composition according to claim 1 which has a peak resistivity of at least 1000 ohm. cm.
Claim 4
Dependent Claim
17 words
A composition according to claim 2 which has a peak resistivity of at least 10,000 ohm. cm.
Claim 5
Dependent Claim
13 words
A composition according to claim 2 wherein said quantity is less than 0.5.
Claim 6
Dependent Claim
13 words
A composition according to claim 4 wherein said quantity is less than 0.3.
Claim 7
Dependent Claim
98 words
A composition according to claim 2 which, after having been subjected to a thermal aging treatment which consists of maintaining the composition, by external heating thereof, for 25 hours at a temperature at which the resistivity of the composition is between 100 ohm. cm and the peak resistivity, (a) exhibits PTC behavior, (b) has a resistivity at at least one temperature between T s and -40° C. which is between 0.5 times and 2 times the resistivity at the same temperature before said thermal aging treatment, and (c) has a peak resistivity of at least 1000 ohm. cm.
Claim 8
Dependent Claim
42 words
A composition according to claim 6 which, after said thermal aging treatment, has, at all temperatures between T s and -40° C., a resistivity which is between 0.5 and 2 times the resistivity at the same temperature before said thermal aging treatment.
Claim 9
Dependent Claim
98 words
A composition according to claim 6 which, after having been subjected to a voltage aging treatment which consists of passing current through the composition for 25 hours so that I 2 R heating thereof maintains the composition at a temperature between T s and (T s +50)° C., (a) exhibits PTC behaviour, (b) has a resistivity at at least one temperature between T s and -40° C. which is between 0.5 times and 2 times the resistivity at the same temperature before said voltage aging treatment and (c) has a peak resistivity of at least 1000 ohm. cm.
Claim 10
Dependent Claim
39 words
A composition according to claim 8 which, after said voltage aging treatment has, at all temperatures within said range, a resistivity which is between 0.5 and 2 times the resistivity at the same temperature before said voltage aging treatment.
Claim 11
Dependent Claim
24 words
A composition according to claim 6 which further comprises at least 0.05% by weight of an additive which stabilises the composition against thermo-oxidative degradation.
Claim 12
Dependent Claim
47 words
A composition according to claim 2 wherein said polymeric component has at least 40% crystallinity and comprises at least one polymer selected from the group consisting of polyolefins, copolymers of at least one olefin and at least one polar comonomer, polyarylenes, polyesters, polyamides, polycarbonates and fluorine-containing polymers.
Claim 13
Dependent Claim
19 words
A composition according to claim 2 wherein said carbon black has a particle size of 20 to 75 millimicrons.
Claim 14
Dependent Claim
23 words
A composition according to claim 2 wherein the ratio by volume of the carbon black to the polymer component is at least 0.25.
Claim 15
Dependent Claim
12 words
A composition according to claim 2 which is substantially free from cross-linking.
Claim 16
Dependent Claim
184 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C., and which, after having been subjected to a thermal aging treatment which consists of maintaining the composition, by external heating thereof, for 25 hours at a temperature at which the resistivity of the composition is between 100 ohm. cm and the peak resistivity, (a) exhibits PTC behavior, and (b) has a resistivity at at least one temperature between T s and -40° C. which is between 0.5 times and 2 times the resistivity of the composition at the same temperature before said thermal aging treatment, and which composition comprises (1) a polymer component having at least 10% crystallinity and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /gram such that S/D is not more than 10.
Claim 17
Dependent Claim
184 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C., and which, after having been subjected to a thermal aging treatment which consists of maintaining the composition, by external heating thereof, for 25 hours at a temperature at which the resistivity of the composition is between 100 ohm. cm and the peak resistivity, (a) exhibits PTC behavior, and (b) has a resistivity at at least one temperature between T s and -40° C. which is between 0.5 times and 2 times the resistivity of the composition at the same temperature before said thermal aging treatment, and which composition comprises (1) a polymer component having at least 10% crystallinity and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /gram such that S/D is not more than 10.
Claim 18
Dependent Claim
17 words
A composition according to claim 15 which has a peak resistivity of at least 1000 ohm. cm.
Claim 19
Dependent Claim
46 words
A composition according to claim 16 which, after having been subjected to said thermal aging treatment, has, at all temperatures between T s and -40° C., a resistivity which is between 0.5 and 2 times the resistivity at the same temperature before said thermal aging treatment.
Claim 20
Dependent Claim
98 words
A composition according to claim 15 which, after having been subjected to a voltage aging treatment which consists of passing current through the composition for 25 hours so that I 2 R heating thereof maintains the composition at a temperature between T s and (T s +50)° C., (a) exhibits PTC behavior, (b) has a resistivity at at least one temperature between T s and -40° C. which is between 0.5 times and 2 times the resistivity at the same temperature before said voltage aging treatment and (c) has a peak resistivity of at least 1000 ohm. cm.
Claim 21
Dependent Claim
40 words
A composition according to claim 18 which, after having said voltage aging treatment has, at all temperatures within said range, a resistivity which is between 0.5 and 2 times the resistivity at the same temperature before said voltage aging treatment.
Claim 22
Dependent Claim
19 words
A claim according to claim 16 wherein said carbon black has a particle size of 20 to 75 millimicrons.
Claim 23
Dependent Claim
108 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature, T s , above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C. and a peak resistivity of at least 1000 ohm. cm and which comprises (1) a polymer component having at least 10% crystallinity and (2) a particulate filter component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 microns and surface area, S, in m 2 /gram such that S/D is not more than 10.
Claim 24
Dependent Claim
108 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature, T s , above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C. and a peak resistivity of at least 1000 ohm. cm and which comprises (1) a polymer component having at least 10% crystallinity and (2) a particulate filter component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 microns and surface area, S, in m 2 /gram such that S/D is not more than 10.
Claim 25
Dependent Claim
27 words
A composition according to claim 21 which has a resistivity of less than 2 ohm. cm at at least one temperature between T s and -40° C.
Claim 26
Dependent Claim
17 words
A composition according to claim 21 which has a peak resistivity of at least 10,000 ohm. cm.
Claim 27
Dependent Claim
40 words
A composition according to claim 21 wherein the amount of said filler component is such that the quantity ##EQU8## is less than 1, and the ratio by volume of the carbon black to the polymer component is at least 0.25.
Claim 28
Dependent Claim
23 words
A composition according to claim 24 wherein the ratio by volume of the carbon black to the polymer component is at least 0.4.
Claim 29
Dependent Claim
154 words
An electrical device which comprises a melt-shaped PTC element and at least two electrodes which can be connected to a source of electrical power and which, when so connected, causes current to flow through said PTC element, said PTC element being composed of a PTC conductive polymer composition which comprises a polymer component having at least 10% crystallinity, and, dispersed in said polymer, a particular filler component which comprises a carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /gram such that S/D is not more than 10; which composition (a) exhibits PTC behavior with a switching temperature T s and a peak resitivity of at least 1000 ohm. cm; and (b) has a resistivity of less than 7 ohm. cm in a temperature range which is between T s and the lower of 0° C. and (T s -50)° C.
Claim 30
Dependent Claim
154 words
An electrical device which comprises a melt-shaped PTC element and at least two electrodes which can be connected to a source of electrical power and which, when so connected, causes current to flow through said PTC element, said PTC element being composed of a PTC conductive polymer composition which comprises a polymer component having at least 10% crystallinity, and, dispersed in said polymer, a particular filler component which comprises a carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /gram such that S/D is not more than 10; which composition (a) exhibits PTC behavior with a switching temperature T s and a peak resitivity of at least 1000 ohm. cm; and (b) has a resistivity of less than 7 ohm. cm in a temperature range which is between T s and the lower of 0° C. and (T s -50)° C.
Claim 31
Dependent Claim
103 words
A device according to claim 26 wherein said PTC composition, after said device has been subjected to a thermal aging treatment which consists of maintaining the device, by external heating thereof, for 25 hours at a temperature at which the resistivity of said composition is between 100 ohm. cm and the peak resistivity, (a) exhibits PTC behavior, (b) has a resitivity at at least one temperature between T s and -40° C. which is between 0.5 times and 2 times the resistivity at the same temperature before said thermal aging treatment, and (c) has a peak resistivity of at least 1000 ohm. cm.
Claim 32
Dependent Claim
45 words
A device according to claim 27 wherein said PTC composition, after said thermal treatment, has at all temperatures between T s and -40° C., a resistivity which is between 0.5 times and 2 times the resistivity at the same temperature before said thermal aging treatment.
Claim 33
Dependent Claim
106 words
A device according to claim 27 wherein said PTC composition after said device has been subjected to a voltage aging treatment which consists of passing current through the device for 25 hours so that I 2 R heating of the device maintains said PTC element at a temperature between T s and (T s +50)° C., (a) exhibits PTC behavior, (b) has a resistivity at at least one temperature between T s and -40° C. which is between 0.5 times and 2 times the resistivity at the same temperature before said voltage aging treatment, and (c) has a peak resistivity of at least 1000 ohm. cm.
Claim 34
Dependent Claim
46 words
A device according to claim 29 wherein said PTC composition, after said voltage aging treatment, has at all temperatures between T s and -40° C., a resistivity which is between 0.5 times and 2 times the resistivity at the same temperature before said voltage aging treatment.
Claim 35
Dependent Claim
24 words
An electrical device according to claim 27 wherein the amount of said filler component is such that the quantity ##EQU9## is less than 1.
Claim 36
Dependent Claim
13 words
A device according to claim 31 wherein said quantity is less than 0.5.
Claim 37
Dependent Claim
23 words
A device according to claim 31 wherein the ratio by volume of said carbon black to said polymer component is at least 0.25.
Claim 38
Dependent Claim
13 words
A device according to claim 33 wherein said ratio is at least 0.40.
Claim 39
Dependent Claim
177 words
A process for the preparation of shaped article of a conductive polymer composition, which process comprises (1) providing (a) a polymer component having at least 10% crystallinity; and (b) a filler component which comprises a carbon black having a particle size, D, which is from 20 to 150 millimicronsand a surface area, S, in m 2 /gram such that S/D is not more than 10, and (2) preparing a composition which comprises a dispersion of said carbon black in said polymer component by a process which comprises dispersing said carbon black in said polymer component while said polymer component is molten; and (3) melt-shaping said dispersion; the total energy used in preparing and melt-shaping said dispersion being from 1 to 300 hp. hr. ft. -3 and being selected so that the product (a) exhibits PTC behavior with a switching temperature T s above 0° C. and a peak resistivity of at least 1000 ohm. cm; and (b) has a resistivity of less that 7 ohm. cm at at least one temperature between T s and -40° C.
Claim 40
Dependent Claim
177 words
A process for the preparation of shaped article of a conductive polymer composition, which process comprises (1) providing (a) a polymer component having at least 10% crystallinity; and (b) a filler component which comprises a carbon black having a particle size, D, which is from 20 to 150 millimicronsand a surface area, S, in m 2 /gram such that S/D is not more than 10, and (2) preparing a composition which comprises a dispersion of said carbon black in said polymer component by a process which comprises dispersing said carbon black in said polymer component while said polymer component is molten; and (3) melt-shaping said dispersion; the total energy used in preparing and melt-shaping said dispersion being from 1 to 300 hp. hr. ft. -3 and being selected so that the product (a) exhibits PTC behavior with a switching temperature T s above 0° C. and a peak resistivity of at least 1000 ohm. cm; and (b) has a resistivity of less that 7 ohm. cm at at least one temperature between T s and -40° C.
Claim 41
Dependent Claim
27 words
A process according to claim 35 wherein the total energy used in preparing and melt-shaping said dispersion is from 1 to 100 hp. hr. ft -3 .
Claim 42
Dependent Claim
20 words
A process according to claim 36 wherein said total energy is from 1 to 50 hp. Hr. ft -3 .
Claim 43
Dependent Claim
20 words
A process according to claim 37 wherein said total energy is from 1 to 25 hp. hr. ft -3 .
Claim 44
Dependent Claim
66 words
A composition according to claim 2 wherein said polymeric component consists essentially of a polymer selected from the group consisting of polyethylene, copolymers of ethylene and ethyl acrylate, copolymers of ethylene and acrylic acid, polyesters, polyamides, polyethers, polycaprolactone, fluorinated ethylene/propylene copolymer, polyvinylidene fluoride, mixtures of polyethylene and a copolymer of ethylene and ethyl acrylate, and mixtures of polyethylene and a copolymer of ethylene and acrylic acid.
Claim 45
Dependent Claim
66 words
A composition according to claim 16 wherein said polymeric component consists essentially of a polymer selected from the group consisting of polyethylene, copolymers of ethylene and ethyl acrylate, copolymers of ethylene and acrylic acid, polyesters, polyamides, polyethers, polycaprolactone, fluorinated ethylene/propylene copolymer, polyvinylidene fluoride, mixtures of polyethylene and a copolymer of ethylene and ethyl acrylate, and mixtures of polyethylene and a copolymer of ethylene and acrylic acid.
Claim 46
Dependent Claim
66 words
A composition according to claim 21 wherein said polymeric component consists essentially of a polymer selected from the group consisting of polyethylene, copolymers of ethylene and ethyl acrylate, copolymers of ethylene and acrylic acid, polyesters, polyamides, polyethers, polycaprolactone, fluorinated ethylene/propylene copolymer, polyvinylidene fluoride, mixtures of polyethylene and a copolymer of ethylene and ethyl acrylate, and mixtures of polyethylene and a copolymer of ethylene and acrylic acid.
Claim 47
Dependent Claim
98 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C.; and which comprises (1) a polymer component having at least 10% crystallinity; and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /grams such that S/D is not more than 10.
Claim 48
Dependent Claim
98 words
A conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40° C.; and which comprises (1) a polymer component having at least 10% crystallinity; and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size, D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /grams such that S/D is not more than 10.
Claim 49
Dependent Claim
140 words
An electrical device which comprises a melt-shapedPTC element and at least two electrodes which can be connected to a source of electrical power and which, when so connected, cause current to flow through said PTC element, said PTC element being composed of a conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40 C., and which comprises (1) a polymer component having at least 10% crystallinity; and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /grams such that S/D is not more than 10.
Claim 50
Dependent Claim
140 words
An electrical device which comprises a melt-shapedPTC element and at least two electrodes which can be connected to a source of electrical power and which, when so connected, cause current to flow through said PTC element, said PTC element being composed of a conductive polymer composition which exhibits PTC behavior with a switching temperature T s above 0° C., which has a resistivity of less than 7 ohm. cm at at least one temperature between T s and -40 C., and which comprises (1) a polymer component having at least 10% crystallinity; and (2) a particulate filler component which has been dispersed in said polymer component and which comprises carbon black having a particle size D, which is from 20 to 150 millimicrons and a surface area, S, in m 2 /grams such that S/D is not more than 10.
References Cited (Backward Citations)
US2978665A
Cited
US3243753A
Cited
US3697450A
Cited
US3760495A
Cited
US3858144A
Cited
US3974105A
Cited
US4124747A
Cited
US4100087A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |