Patent US6166914A successfully refreshed from Google Patents.
US5280263A
Expired / Lapsed
US
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PTC device
Assignee: Daito Communication Apparatus Co Ltd
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Filing: 1991-10-30
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Granted: 1994-01-18
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Expires: 2011-10-30
Abstract
Abstract A PTC element displaying low volume resistivity and excellent PTC characteristics contains conductive carbonaceous particles having a large particle size, small specific surface area and being essentially unstructured such particles being, for example, thermal black or mesocarbon microparticles. The conductive particles are heat treated in an inactive atmosphere, blended with a crystalline polymer and then cross-linked by gamma radiation. In a variant form, the polymer can be chemically grafted onto the particles. The very low resistivity and excellent PTC characteristics of this PTC device make it suitable for miniaturization.
Inventors
- 👤 Shoichi Sugaya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:08
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/027
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
70 words
In a PTC device, a PTC element comprised of a crystalline polymer mass having essentially unstructured conductive carbonaceous particles dispersed therethrough the conductive carbonaceous particles being separable one from another upon thermal expansion of the polymer, and the conductive carbonaceous particles having the volume resistivity of particle mass of not more than 0.05 ohm ·cm with a compression force of from about 640 to about 960 kgf/cm 2 applied thereto.
Claim 2
Dependent Claim
70 words
In a PTC device, a PTC element comprised of a crystalline polymer mass having essentially unstructured conductive carbonaceous particles dispersed therethrough the conductive carbonaceous particles being separable one from another upon thermal expansion of the polymer, and the conductive carbonaceous particles having the volume resistivity of particle mass of not more than 0.05 ohm ·cm with a compression force of from about 640 to about 960 kgf/cm 2 applied thereto.
Claim 3
Dependent Claim
13 words
The PTC device of claim 1, wherein the conductive particles are thermal black.
Claim 4
Dependent Claim
13 words
The PTC device of claim 1, wherein the conductive particles are mesocarbon microbeads.
Claim 5
Dependent Claim
19 words
The PTC device of claim 1, in which the conductive particles are pretreated by heating in an inactive atmosphere.
Claim 6
Dependent Claim
15 words
The PTC device of claim 4, in which the inactive atmosphere is that of nitrogen.
Claim 7
Dependent Claim
39 words
A PTC device of claim 1, in which the crystalline polymer are grafted onto the conductive carbonaceous particles, the graft being effected by thermal blending of the conductive particles and crystalline polymer in the presence of an organic peroxide.
Claim 8
Dependent Claim
112 words
In a PTC device, a PTC element comprised of a crystalline polymer mass having essentially unstructured conductive carbon particles substantially uniformly dispersed therethrough the conductive particles being separable one from another upon thermal expansion of the polymer, the conductive carbonaceous particles having the volume resistivity of particle mass of not more than 0.05 ohm·cm with a compression force of from about 640 to about 960 kgf/cm 2 applied thereto, the conductive carbonaceous particles being pretreated by heating it in an inactive atmosphere, with the conductive carbon particles being grafted to the crystalline polymer by thermally blending of the conductive carbon particles with the crystalline polymer in the presence of an organic peroxide.
Claim 9
Dependent Claim
112 words
In a PTC device, a PTC element comprised of a crystalline polymer mass having essentially unstructured conductive carbon particles substantially uniformly dispersed therethrough the conductive particles being separable one from another upon thermal expansion of the polymer, the conductive carbonaceous particles having the volume resistivity of particle mass of not more than 0.05 ohm·cm with a compression force of from about 640 to about 960 kgf/cm 2 applied thereto, the conductive carbonaceous particles being pretreated by heating it in an inactive atmosphere, with the conductive carbon particles being grafted to the crystalline polymer by thermally blending of the conductive carbon particles with the crystalline polymer in the presence of an organic peroxide.
Claim 10
Dependent Claim
14 words
The PTC device of claim 7, in which the conductive particles are thermal black.
Claim 11
Dependent Claim
14 words
The PTC device of claim 7, in which the conductive particles are mesocarbon microbeads.
Claim 12
Independent Claim
74 words
A method for making a PTC element, comprising the steps of: thermally treating conductive carbonaceous particles in an inert atmosphere at a temperature and for a time effective to produce a volume resistivity of not more than 0.05 ohm-cm under a compression force of from about 640 to about 960 kgf/cm 2 , blending the conductive carbonaceous particles with a crystalline polymer in a roll mill at constant temperature to form a blended mixture.
Claim 13
Independent Claim
74 words
A method for making a PTC element, comprising the steps of: thermally treating conductive carbonaceous particles in an inert atmosphere at a temperature and for a time effective to produce a volume resistivity of not more than 0.05 ohm-cm under a compression force of from about 640 to about 960 kgf/cm 2 , blending the conductive carbonaceous particles with a crystalline polymer in a roll mill at constant temperature to form a blended mixture.
Claim 14
Dependent Claim
26 words
The method of claim 10 in which the roll mill blending is carried out at a constant temperature of above the melting point of crystalline polymers.
Claim 15
Dependent Claim
22 words
The method of claim 10 further comprising adding an organic peroxide to the conductive particle/crystalline polymer during the roll mill blending step.
Claim 16
Dependent Claim
25 words
The method of claim 12 in which the mill blending is carried out at a constant temperature of above the melting point of crystalline polymers.
Claim 17
Dependent Claim
26 words
The method of claim 10 in which the compression mold is heated to between about 160 and about 240 degrees C. and maintained under a pressure.
Claim 18
Dependent Claim
25 words
The method of claim 10 in which following annealing, the element is subjected to radiation of gamma radiation to affect cross linking of the polymer.
Claim 19
Dependent Claim
14 words
The method of claim 10 in which the inactive atmosphere is that of nitrogen.
Claim 20
Dependent Claim
24 words
The PTC device of claim 1, wherein the conductive carbonaceous particles have a specific surface area of not more than 6 m 2 /g.
Claim 21
Dependent Claim
24 words
The PTC device of claim 7, wherein the conductive carbon particles have a specific surface area of not more than 6 m 2 /g.
Claim 22
Dependent Claim
23 words
The PTC device of claim 10, wherein the conductive carbonaceous particles have a specific surface area of not more than 6 2 /g.
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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) | 1997-01-17 | 1997-07-19 | 1998-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-17 | 2001-07-19 | 2002-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-17 | 2005-07-19 | 2006-01-18 | $7700.00 | Window Closed / Lapsed |