WO1994006128A1 - An electric device which utilizes conductive polymers having a positive temperature coefficient characteristic - Google Patents

An electric device which utilizes conductive polymers having a positive temperature coefficient characteristic Download PDF

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Publication number
WO1994006128A1
WO1994006128A1 PCT/KR1993/000078 KR9300078W WO9406128A1 WO 1994006128 A1 WO1994006128 A1 WO 1994006128A1 KR 9300078 W KR9300078 W KR 9300078W WO 9406128 A1 WO9406128 A1 WO 9406128A1
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WO
WIPO (PCT)
Prior art keywords
subelements
electric device
conductive
electrodes
conductive polymer
Prior art date
Application number
PCT/KR1993/000078
Other languages
French (fr)
Inventor
Hwa Joon Lim
Tai Min Kim
Byung Chun Lee
Gun Joo Lee
Original Assignee
Gold Star Cable Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gold Star Cable Co., Ltd. filed Critical Gold Star Cable Co., Ltd.
Publication of WO1994006128A1 publication Critical patent/WO1994006128A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
    • H01C7/027—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/146—Conductive polymers, e.g. polyethylene, thermoplastics

Definitions

  • the present invention relates to an electric device which utilizes conductive polymers having a positive temperature coefficient characteristic. More particularly, this invention relates to electric devices which utilize at least two conductive polymer elements.
  • the circuit protection element(current limiting element) including conductive polymers showing a positive temperature coefficient behaviour utilizes a property, a PTC characteristic in the conductive polymer composition.
  • the above polymer composition is produced by mixing conductive carbon black and insulating polymer having the characteristic of positive expansion according to the temperature and dispersing conductive carbon black therein, and the electric resistance thereof increases positively with temperature.
  • the above element is placed between a circuit i. e.
  • the conventional circuit protection devices including conductive polymers exhibiating a positive temperature behaviour, are composed of an optionally shaped conductive polymer and two electrodes to be contected to a source of electrical power.
  • the electric device of the present invention comprises at least two subelements including a conductive polymer exhibiting positive temperature coefficient characteristic as a result of dispersing therein a conductive carbon black, and the subelements contain at least one or two electrodes attached thereto such that current flows through the above conductive polymer, wherein the electrodes of the above subelements are connected to each other in parallel, and are placed adjacently to each other enough to exchange heat easily and an insulating material is sandwiched between the above subelements in order to insulate the above subelements each other.
  • the electric device of the present invention also includes at least two electrodes attached to connect a source of electrical power.
  • Figure 1 is the resistance/temperature curve showing a positive temperature coefficient characteristic of each of the subelements in the electric devices which include these subelements according to the present invention.
  • Figure 2 is a sectional perspective view of a conventional disk-type circuit protection element.
  • Figure 3 is a sectional perspective view of a disk-type electric device accdording to the present invention.
  • Figure 4 is a sectional perspective view of a disk-type electric device according to the present invention.
  • Figure 5 is a perspective view of a block-type electric device according to the present invention.
  • Figure 6 is a perspective view of a block-type electric device according to the present invention.
  • Figure 7 is a diagram showing the trip times of a conventional single conductive polymer circuit protection element and an electric device embodied according to the present invention, respectively.
  • Figure 3 and Figure 4 are sectional perspective views of disk-type electric devices according to the present invention.
  • the disk-type electric device comprises at least two subelements 6, 7 with at least one or two thin electrodes 4 attached to a thin conductive polymer 3 having a positive temperature coefficient characteristic such that current flows through said conductive polymer 3.
  • Said subelements 6, 7 are placed adjacently to each other and isolated by an insulating materials 5 placed between them.
  • the electrodes 4 of said subelements 6, 7 are connected in parallel.
  • This electric device also includes at least two electrodes 8 attached to connect a source of electrical power.
  • Figure 5 and Figure 6 illustrate block-type electric device for circuit protection according to the present invention.
  • the block-type electric device inludes at least two subelements 6, 7 produced by extruding conductive polymers having a positive temperature coefficient characteristic together with at least one or two cord-type electrodes 4 such that current flows through said conductive polymers 3 and cutting them to optional length. Said subelements 6, 7 are installed adjacently to each other and isolated by an insulating material 5 placed between them.
  • This electric device also includes at least two electrodes 8 for connection to a power source of electric power.
  • An elct ⁇ c device wherein said subelements 6,7 are installed adjacently to each other without insulating material 5 between them can also be formed.
  • the conductive polymer be polyethylene hav'ing at least 10 weight% crystallinity and conductive carbon black dispersed therein or be the polymer containing fluorine naving at least 10 weight% crystallinity and conductive carbon black dispersed therein or be crosslinked by irradition and that at least one subelement formed of such a material be included. It is also desirable that at least one of said subelements comprises the mixture consiting of a conductive polymer including polyethylene having at least 10 weight% crystallinity and conductive carbon black dispersed therein and an ethylen-ethyl aerylate copolymer.
  • the conductive carbon black contained in a polymer have a particle size less than 150nm and the conductive polymers of the subelements forming an electric device have volume resistance less than 100 ⁇ cm, preferably less than 10 ⁇ cm, particularly less than 1 ⁇ m.
  • the electric device inculde at least two subelements wherein the conductive polymer of a subelement has a positive temperature coefficient characteristic different from the conductive polymers of the other subelements which form said electric device, that the electric device include at least one of subelements wherein the switching temperature Ts of one subelement is different from the temperatures Ts of the other subelements which form said electric device, and that the electric device has a switching temperature Ts higher than 0°C, and the electric resistance of said electric device be lower than 20 ⁇ preferably lower then 5 ⁇ particularly lower than 1 ⁇ in the temperature range between -40°C and Ts.
  • At least one of subelements composing the electric device is made to have a positive temperature coefficient characteristic different from those of the other subelements of said electric device by differring from conductive polymers of in a conductive polymer and in the material itself of a conductive polymer as illustrated in Figure 1 which is characteristic curves showing the relationship between the temperature T and volume resistance V.R. ; and thus it is made to have a rate of increase in resistance different from the other subelements over a temperature range between the temperature of a normal operating state, Tn, and the temperature of being tripped Tt.
  • said subelements different from each other in positive temperature coefficient characteristic can shorten the "trip time" by mutual energy in causing the temperature and the resistance of the device to reach rapidly the high temperature and high resistance conditions.
  • the conductive polymer which forms an electric device contains a large amount of carbon black to have a low resistance under the normal operation state.
  • a plurality of subelements composed of conductive polymers are connected to each other in parallel, so that the conductive polymer of each subelement can contain a relatively small amount of carbon black and thereby have a low resistance value.
  • a disk-type element comprises a circular (or optionally shaped such as quadri-lateral)thin conductive polymer and thin metal electrodes attached thereto , as illustrated in Figure 2, an incidence of joint resistance between the thin metal electrode and polymer due to the relpeated and reset is relatively reducible, so that voltage safety of element can be promoted.
  • a block-type element is manufactured by cutting an extruded strip as illustrated in Figure 4, it can also be processed under a relative soft condition in this invention as compared with in prior art using a conductive polymer containing a large amount of carbon black.
  • DGDK 3364 DGDK 3364
  • a fixed quantity of carbon black LCKY Continex GPE, ASTM N660 grade
  • the sample was irradiation crosslinked.
  • a thin plate 0.7mm thick were then prepared by mold-compressing Nickel foil 0.04mm thick at the temperature of 250°C and a pressure of about 300 kg/cm 2 and attaching it to both faces of the above sample.
  • Disk 10mm in diameter were punched out of the above thin plate.
  • the above round disk was used as subelement No.1.
  • a thin plate 0.7mm thick were then prepared by mold-compressing Nickel foil 0.04mm thick at the temperature of

Abstract

The present invention relates to an electric device which utilizes conductive polymers having a positive temperature coefficient characteristic. In this invention, at least two subelements (6, 7) are included with at least one or two electrodes (4) attached to an optionally shaped conductive polymer (3) which contains conductive carbon black dispersed therein and has a positive temperature coefficient characteristic such that current flows through said conductive polymer (3). The electrodes (4) of said subelements are connected in parallel to each other and installed adjacently to each other for easy exchange of heat, said subelements (6, 7) are isolated by insulating material (5) placed between them and at least two electrodes (4) attached to connect to a source of electrical power, the electrodes (4) of said subelements (6, 7) connected in parallel are included. As compared with the conventional circuit protection element formed of a single conductive polymer, this invention produces the effect of shortening trip time and reset time.

Description

AN ELECTRIC DEVICE WHICH UTILIZES CONDUCTIVE POLYMERS HAVING A POSITIVE TEMPERATURE COEFFICIENT CHARACTERISTIC
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an electric device which utilizes conductive polymers having a positive temperature coefficient characteristic. More particularly, this invention relates to electric devices which utilize at least two conductive polymer elements.
Description of the Prior Art
The circuit protection element(current limiting element) including conductive polymers showing a positive temperature coefficient behaviour utilizes a property, a PTC characteristic in the conductive polymer composition.
The above polymer composition is produced by mixing conductive carbon black and insulating polymer having the characteristic of positive expansion according to the temperature and dispersing conductive carbon black therein, and the electric resistance thereof increases positively with temperature. The above element is placed between a circuit i. e. , load and a source of electrical power and therefore, when excessive currents (and the voltages which produced such currents)are applied to the conductive polymers and thus their conductive polymers generate heat by I 2R heating, the temperature of the conductive polymers rises and thereby the electric resistance thereof increases to the high resistance condition (wherein such transfer is called switching temperature Ts)so that the protection of circuits against excessive currents can be obtained by breaking circuits, wherein the time taken to convert the PTC element into a high resistance, high temperature state such that the circuit current is reduced to a safe level, is called the "trip time".
In addition, when the excessive currents are reduced to a sufficiently low level, the temperature of the element is lower, thus the element is reduced to the low-resistance, normal operating condition ; therefore the load circuit can be protected against excessive currents continuously without replacing the element with the another. The conventional circuit protection devices including conductive polymers exhibiating a positive temperature behaviour, are composed of an optionally shaped conductive polymer and two electrodes to be contected to a source of electrical power.
At this result, major problems assoiated with these conventional circuit protect devices are as follows : (1) The trip of the device due to the excessive current, depends largely on a short of the conducting passage of carbon black dispersed in the conductive polymer by the thermal expansion of the conductive polymer ; and thus it takes at least several seconds for the PTC element to be converted into a high resistance, high temperature state .such that the circuit current is reduced to a safe level.
(2) Even in resetting operation, it takes relatively long time, i. e., at least several minutes to release the heat absorbed in the device and return to the normal operation condition.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention herein to provide an electric device particularly useful in circuits carrying a steady state current, of which the trip time and the resetting time are shorter than those of the conventional single conductive polymer element. The electric device of the present invention comprises at least two subelements including a conductive polymer exhibiting positive temperature coefficient characteristic as a result of dispersing therein a conductive carbon black, and the subelements contain at least one or two electrodes attached thereto such that current flows through the above conductive polymer, wherein the electrodes of the above subelements are connected to each other in parallel, and are placed adjacently to each other enough to exchange heat easily and an insulating material is sandwiched between the above subelements in order to insulate the above subelements each other. The electric device of the present invention also includes at least two electrodes attached to connect a source of electrical power.
Description cf the Drawings
Figure 1 is the resistance/temperature curve showing a positive temperature coefficient characteristic of each of the subelements in the electric devices which include these subelements according to the present invention.
Figure 2 is a sectional perspective view of a conventional disk-type circuit protection element.
Figure 3 is a sectional perspective view of a disk-type electric device accdording to the present invention. Figure 4 is a sectional perspective view of a disk-type electric device according to the present invention.
Figure 5 is a perspective view of a block-type electric device according to the present invention. Figure 6 is a perspective view of a block-type electric device according to the present invention.
Figure 7 is a diagram showing the trip times of a conventional single conductive polymer circuit protection element and an electric device embodied according to the present invention, respectively.
Detailed Description of the Invention
The preseant invention will now be described according to the drawing attached hereto.
Figure 3 and Figure 4 are sectional perspective views of disk-type electric devices according to the present invention.
The disk-type electric device comprises at least two subelements 6, 7 with at least one or two thin electrodes 4 attached to a thin conductive polymer 3 having a positive temperature coefficient characteristic such that current flows through said conductive polymer 3. Said subelements 6, 7 are placed adjacently to each other and isolated by an insulating materials 5 placed between them. The electrodes 4 of said subelements 6, 7 are connected in parallel. This electric device also includes at least two electrodes 8 attached to connect a source of electrical power. Figure 5 and Figure 6 illustrate block-type electric device for circuit protection according to the present invention.
The block-type electric device inludes at least two subelements 6, 7 produced by extruding conductive polymers having a positive temperature coefficient characteristic together with at least one or two cord-type electrodes 4 such that current flows through said conductive polymers 3 and cutting them to optional length. Said subelements 6, 7 are installed adjacently to each other and isolated by an insulating material 5 placed between them. This electric device also includes at least two electrodes 8 for connection to a power source of electric power.
An elctπc device wherein said subelements 6,7 are installed adjacently to each other without insulating material 5 between them can also be formed.
It is desirable that the conductive polymer be polyethylene hav'ing at least 10 weight% crystallinity and conductive carbon black dispersed therein or be the polymer containing fluorine naving at least 10 weight% crystallinity and conductive carbon black dispersed therein or be crosslinked by irradition and that at least one subelement formed of such a material be included. It is also desirable that at least one of said subelements comprises the mixture consiting of a conductive polymer including polyethylene having at least 10 weight% crystallinity and conductive carbon black dispersed therein and an ethylen-ethyl aerylate copolymer.
It is also desirable that the conductive carbon black contained in a polymer have a particle size less than 150nm and the conductive polymers of the subelements forming an electric device have volume resistance less than 100Ωcm, preferably less than 10Ωcm, particularly less than 1Ωm.
It is further desirable that the electric device inculde at least two subelements wherein the conductive polymer of a subelement has a positive temperature coefficient characteristic different from the conductive polymers of the other subelements which form said electric device, that the electric device include at least one of subelements wherein the switching temperature Ts of one subelement is different from the temperatures Ts of the other subelements which form said electric device, and that the electric device has a switching temperature Ts higher than 0°C, and the electric resistance of said electric device be lower than 20Ω preferably lower then 5Ω particularly lower than 1Ω in the temperature range between -40°C and Ts. An electric device for protecting the circuit against excessive current according to the present invention produces the following effects.
First, at least one of subelements composing the electric device is made to have a positive temperature coefficient characteristic different from those of the other subelements of said electric device by differring from conductive polymers of in a conductive polymer and in the material itself of a conductive polymer as illustrated in Figure 1 which is characteristic curves showing the relationship between the temperature T and volume resistance V.R. ; and thus it is made to have a rate of increase in resistance different from the other subelements over a temperature range between the temperature of a normal operating state, Tn, and the temperature of being tripped Tt.
Therefore, at the tripping operation of said elements, said subelements different from each other in positive temperature coefficient characteristic can shorten the "trip time" by mutual energy in causing the temperature and the resistance of the device to reach rapidly the high temperature and high resistance conditions.
Second, even in resetting operation after tripping, (1) as the subelements of electric device exchange heat each other, the rate at which heat is lost from the device is a little high, and (2) when subelements reach equal temperature, a current is passed through the subelement having lower resistance and P=IR energy than the other elements. Therefore, reset time taken to convert the circuit into the normal operating conditions after the excessive current is removed in the electric device according to this invention is much shorter than in the conventional circuit protection device formed of a single element. Third, in the case where an excessive current which is more than necessary but not enough to damage the function of load circuit, the conventional circuit protection device composed of a single element can not easily lose the thermal energy generated by itself due to high temperature of the environments, so that the device may be "tripped" . i. e., converted into a high resistance state, when a fault condition, e. g. , excessive current or temperature occurs. In the convention electric device, the conductive polymer which forms an electric device contains a large amount of carbon black to have a low resistance under the normal operation state. In the prevent invention, however, a plurality of subelements composed of conductive polymers are connected to each other in parallel, so that the conductive polymer of each subelement can contain a relatively small amount of carbon black and thereby have a low resistance value. Therefore, in the case where a disk-type element comprises a circular (or optionally shaped such as quadri-lateral)thin conductive polymer and thin metal electrodes attached thereto , as illustrated in Figure 2, an incidence of joint resistance between the thin metal electrode and polymer due to the relpeated and reset is relatively reducible, so that voltage safety of element can be promoted. When a block-type element is manufactured by cutting an extruded strip as illustrated in Figure 4, it can also be processed under a relative soft condition in this invention as compared with in prior art using a conductive polymer containing a large amount of carbon black. EXAMPLE
An insulating polymer, polyethylene (HDPE, UNION CARBIDE
DGDK 3364), and a fixed quantity of carbon black (LUCKY Continex GPE, ASTM N660 grade) were melt-mixed in Banbury mixer and were then compression molded at the temperature of 170°C and a pressure of about 200 kg/cm 2 into a thin plate 1mm thick. The sample was irradiation crosslinked. A thin plate 0.7mm thick were then prepared by mold-compressing Nickel foil 0.04mm thick at the temperature of 250°C and a pressure of about 300 kg/cm 2 and attaching it to both faces of the above sample. Disk 10mm in diameter were punched out of the above thin plate. The above round disk was used as subelement No.1.
An polymer containing fluorine, polyvinylidin fluoride (PVDF, ATO CHEM 460) and a fixed quantity of carbon black (Cabot Vulcan Xc-72, ASTM N427 grade) were melted and mixed in Banbury mixer and were then compression molded at the temperature of 200°C and a pressure of about 200 kg/cm 2into a thin plate 1mm thick. The sample was irradiation-crosslinked.
A thin plate 0.7mm thick were then prepared by mold-compressing Nickel foil 0.04mm thick at the temperature of
250"C and a pressure of about 300 kg/cm 2 and attaching it to both faces of the above sample. Disk 10mm in diameter were punched out of the above thin plate. The above round disk was used as subelement No.2.
After these two subelements are installed by placing one over the other with a solid insulating material 0.1mm thick between them, the extended portions of nickel foil electrodes of two subelements are connected in parallel to each other and two electrodes are soldered thereto. The exterior of said subelements were then epoxy-molded to an average thickness of 0.5mm. An electric device which consists of two subelements had a resistance of 1β at 10βC .
A electric device as described in example placed in circuit consisting of the device, a resistor of 25 ohms in series with the device and AC power supply, and its trip and reset time was observed. According to the observation. Trip time was shortened and reset time was also shortened by 30 seconds to one minute as compared with the conventional circuit protection element formed of single conductive polymer element, as illustrated in Figure 7 showing the relationship between the trip time, t and the initial current, I. Having described the preferred example of the present invention, it will appear to those ordinarily skilled in the art that various modifications may be made to the disclosed embodiments, and that such modifications are intended to be within the scope of the present invention.

Claims

1. An electric device comprises at least two subelements including conductive polymer composites showing the positive temperature coefficient characteristic as a result of dispersing therein the conductive carbon black, and the said subelements contain at least one electrode attached thereto such that the current flows through the said conductive polymer, composites wherein said electrodes of the said subelements are connected to each other in parallel and are placed adjacently to each other enough to make their heat exchange easy, and the insulating material ane sandwiched between said subelements to insulate the space between the said subelements, and said electric device includes at least two electrodes attached to connect the said electrodes of subelements connected in parallel to the source of electrical power.
2. An electrical device according to claim 1, wherein at least one of the said subelements comprises the conductive polymer composite consisting of the polyethylene having at least 10 weight crystallinity and the conductive carbon black dispersed therein.
3. An electric device according to claim 1, wherein at least one of the said subelements comprises the conductive polymer composite consisting of the mixture of the polyethylene having at least 10 weights crystallinity and the ethylene-ethyl acrylate copolymer, and the conductive carbon black dispersed therein.
4. An electric device according to claim 1, wherein at least one of the said subelements comprises a conductive polymer composite containing the fluorine having at least 10 weight* crystallinity and fluoropolymer having at least 10 weight* crystallinity and the conductive carbon black disperesed therein.
5. An electric device according to claim 1, wherein at least one of the said subelements comprises the conductive polymer composite crosslinked.
6. An electric device according to claim 1, 2, 3, 4 or 5,wherein the said electric device includes at least two subelements wherein the conductive polymer composite which forms one subelements has a positive temperature coefficient characteristic different from the polymer positive temperature coeffcient characteristic of the conductive composities which form the other subelements included in said electric device.
7. An electric device according to claim 1, 2, 3, 4 or 5, wherein the said elements which consist the said electric device are placed partially adjacently to each other.
8. An electric device according to claim 1, 2, 3, 4 or 5, wherein said conductive polymers contain the conductive carbon black having a particle size from 20nm to 150nm in the diameter.
9. An electric device according to claim 1, 2, 3, 4 or 5, wherein the conductive polymers of said subelements have volume resistance less than 100Ωcm, preferably less than 10Ωcm, particularly less than 1Ωcm.
10. An electric device according to claim 1, 2, 3, 4 or 5, wherein said electric device has a switching temperature higher than 0°C and the electric resistance of said electric device is lower than 20Ω , prreferably lower than 5Ω , particularly lower than 1Ω at least one point of temperature between -40°C and Ts.
11. An electric device according to claim 1, 2, 3, 4 or 5, wherein at least one of subelements which form said electric device has the switching temperature Ts different from the switching temperature Ts of the other subelements which form said electric device.
12. An electric device comprises at least two subelements including conductive polymers exhibiting a positive temperature coefficient behaviour as a result of dispersing therein conductive carbon black , and said subelements contain at least one electrode attached thereto such that the current flows through said conductive polymers, wherein said electrodes of said subelements are connected to each other in parallel and are placed adjacently to each other enough to exchange heat easily, and said electric device includes at least two electrodes attached to connect said electrodes of subelements connected in parallel to the source of electrical power.
PCT/KR1993/000078 1992-09-01 1993-09-01 An electric device which utilizes conductive polymers having a positive temperature coefficient characteristic WO1994006128A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1992-15820 1992-09-01
KR1019920015820A KR950013344B1 (en) 1992-09-01 1992-09-01 Electric apparatus using ptc conductive high polymer

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WO1994006128A1 true WO1994006128A1 (en) 1994-03-17

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0762437A2 (en) * 1995-08-11 1997-03-12 Eaton Corporation Electrical circuit protection devices comprising PTC conductive liquid crystal polymer compositions
WO1997049102A1 (en) * 1996-06-19 1997-12-24 Littelfuse, Inc. Electrical apparatus for overcurrent protection of electrical circuits
WO1999005689A1 (en) * 1997-07-25 1999-02-04 Tyco Electronics Corporation Electrical device comprising a conductive polymer
WO2014188191A1 (en) * 2013-05-21 2014-11-27 Heat Trace Limited Electrical heater
EP3595404A1 (en) * 2018-07-11 2020-01-15 Goodrich Corporation Multi polymer positive temperature coefficient heater
CN112185634A (en) * 2019-07-01 2021-01-05 力特保险丝公司 PPTC device with resistor element

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Publication number Priority date Publication date Assignee Title
DE3213558A1 (en) * 1981-04-13 1982-10-21 Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto PTC RESISTANCE ARRANGEMENT
US4876440A (en) * 1976-12-13 1989-10-24 Raychem Corporation Electrical devices comprising conductive polymer compositions
US4924074A (en) * 1987-09-30 1990-05-08 Raychem Corporation Electrical device comprising conductive polymers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4876440A (en) * 1976-12-13 1989-10-24 Raychem Corporation Electrical devices comprising conductive polymer compositions
DE3213558A1 (en) * 1981-04-13 1982-10-21 Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto PTC RESISTANCE ARRANGEMENT
US4924074A (en) * 1987-09-30 1990-05-08 Raychem Corporation Electrical device comprising conductive polymers

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0762437A2 (en) * 1995-08-11 1997-03-12 Eaton Corporation Electrical circuit protection devices comprising PTC conductive liquid crystal polymer compositions
EP0762437A3 (en) * 1995-08-11 1998-01-14 Eaton Corporation Electrical circuit protection devices comprising PTC conductive liquid crystal polymer compositions
WO1997049102A1 (en) * 1996-06-19 1997-12-24 Littelfuse, Inc. Electrical apparatus for overcurrent protection of electrical circuits
US5808538A (en) * 1996-06-19 1998-09-15 Littelfuse, Inc. Electrical apparatus for overcurrent protection of electrical circuits
WO1999005689A1 (en) * 1997-07-25 1999-02-04 Tyco Electronics Corporation Electrical device comprising a conductive polymer
US6104587A (en) * 1997-07-25 2000-08-15 Banich; Ann Electrical device comprising a conductive polymer
WO2014188191A1 (en) * 2013-05-21 2014-11-27 Heat Trace Limited Electrical heater
EP3595404A1 (en) * 2018-07-11 2020-01-15 Goodrich Corporation Multi polymer positive temperature coefficient heater
US11166343B2 (en) 2018-07-11 2021-11-02 Goodrich Corporation Multi polymer positive temperature coefficient heater
CN112185634A (en) * 2019-07-01 2021-01-05 力特保险丝公司 PPTC device with resistor element

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KR950013344B1 (en) 1995-11-02

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122 Ep: pct application non-entry in european phase