CA2050339C - Insulated wire for high temperature use - Google Patents

Insulated wire for high temperature use

Info

Publication number
CA2050339C
CA2050339C CA 2050339 CA2050339A CA2050339C CA 2050339 C CA2050339 C CA 2050339C CA 2050339 CA2050339 CA 2050339 CA 2050339 A CA2050339 A CA 2050339A CA 2050339 C CA2050339 C CA 2050339C
Authority
CA
Canada
Prior art keywords
metal oxide
oxide layer
insulating metal
insulated wire
conductor
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Fee Related
Application number
CA 2050339
Other languages
French (fr)
Other versions
CA2050339A1 (en
Inventor
Kazuo Sawada
Shinji Inazawa
Kouichi Yamada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sumitomo Electric Industries Ltd
Original Assignee
Sumitomo Electric Industries 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 Sumitomo Electric Industries Ltd filed Critical Sumitomo Electric Industries Ltd
Publication of CA2050339A1 publication Critical patent/CA2050339A1/en
Application granted granted Critical
Publication of CA2050339C publication Critical patent/CA2050339C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00Insulated conductors or cables characterised by their form
    • H01B7/17Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/29Protection against damage caused by extremes of temperature or by flame
    • H01B7/295Protection against damage caused by extremes of temperature or by flame using material resistant to flame
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/10Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances metallic oxides
    • H01B3/105Wires with oxides
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00Insulated conductors or cables characterised by their form
    • H01B7/17Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/29Protection against damage caused by extremes of temperature or by flame
    • H01B7/292Protection against damage caused by extremes of temperature or by flame using material resistant to heat

Abstract

Disclosed is an insulated wire which comprises a conductor, a first insulating metal oxide layer which is formed around the conductor, and a second insulating metal oxide layer, containing ceramics particles mixed by addition, which is formed around the first insulating metal oxide layer. The aforementioned insulating metal oxide layers can be formed by changing a precursor of a metal oxide to a ceramics state, using a method such as a sol-gel method or a thermal decomposition method. Further, the mixed ceramics particles are more preferably in the form of a fine plate. This insulated wire is excellent in flexibility, emits no gas, can maintain insulation even under a high temperature, and has a high breakdown voltage.

Description

~oso ~ ~9 -INSULATED WIRE FOR HIGH TEMPERATURE USE

Technical Field The present invention relates to an insulated wire, and more particularly, it relates to an insulated wire, a fireproof wire or the like, which can be used under high-temperature or high-vacuum environment.
Background Art In general, an insulated wire whose conductor is coated with heat-resistant organic resin such as polyimide, fluororesin or the like has been employed in equipment such as heating equipment or a fire alarm, for which safety under a high temperature is required, or environment in an automobile, which is heated to a high temperature.
In general, further, an insulated wire whose conductor is passed through a ceramic insulator tube, or a MI cable (Mineral Insulated Cable) whose conductor is passed through a heat-resistant alloy tube of a stainless steel alloy which is filled up with metal oxide particulates of magnesium oxide or the like, etc., has been employed in a case for which particularly high heat resistance is required or in environment for which a high degree of vacuum is required.

Z05(~3;39 On the other hand, a fiber-glass braided insulated wire employing textile of glass fiber as an insulating member or the like can be mentioned as an insulated wire having flexibility, which can be used under high-temperature environment. As an insulated wire which isexcellent in heat resistance, insulation and heat dissipativity, there exists the so-called alumite wire, which is prepared by anodizing a wire of an aluminum alloy.
Further, there has also been proposed an insulated wire which is prepared by employing a material such as a metal alkoxide or a metal organic acid salt, being changeable to a ceramics state, and forming a ceramics film around a conductor.
In the aforementioned insulated wire whose conductor is coated with heat resistant organic resin, a temperature under which insulation can be maintained is about 300~C at the most. Therefore, it has been impossible to apply such an insulated wire to a use for which insulation is required even under a higher temperature.
On the other hand, the aforementioned insulated wire whose conductor is passed through a ceramics insulator tube has had such a disadvantage that the same is inferior in flexibility although its insulation can be maintained under a high temperature. Further, although the -205C~339 aforementioned MI cable can maintain insulation under a high temperature and is flexible as compared with the aforementioned wire whose conductor is passed through a ceramics insulator tube, difficulty is caused when the same is bent with large curvature.
Further, the aforementioned fiber-glass braided insulated wire can maintain insulation even under a high temperature, and is excellent in flexibility. However, it has been impossible to use this wire under environment for which a high degree of vacuum is required, since the same easily discharges dust.
On the other hand, the aforementioned alumite wire can maintain insulation even under a high temperature, and has some flexibility. However, application of the wire has been restricted since the conductor employed for the wire is restricted to aluminum alone.
As to the aforementioned insulated wire which is prepared by forming a ceramics layer around a conductor, further, the ceramics layer is mostly a single layer having a small layer thickness, and it has been difficult to increase the breakdown voltage, although the wire is excellent in flexibility.
Disclosure of the Invention An object of the present invention is to solve the aforementioned problems of the conventional insulated ~50 ~39 _ .

wires, and to provide an insulated wire which has the following properties:
(a) Capability of maintaining insulation even under a high temperature.
(b) Superiority in flexibility.
(c) No emission of gas.
(d) Capability of employing various types of conductors.
(e) Possession of a high breakdown voltage.
The insulated wire according to the present invention comprises a conductor, a first insulating metal oxide layer formed around the conductor, and a second insulating metal oxide layer, containing ceramics particles mixed by addition, formed around the first insulating metal oxide layer, wherein the first insulating metal oxide layer and/or the second insulating metal oxide layer is formed by baking a precursor containing at least one compound selected from the group consisting of alkoxides and organic acid salts of Si, Zr, Al and Ti.
The insulating metal oxide layer(s) can be applied to the periphery of a conductor and the same can be changed to a ceramics state by heating, using a method such as a sol-gel method, a thermal decomposition method or the like.
A more preferable insulated wire is implemented if the ceramics particles contained in the second insulating -Z05~339 metal oxide layer of the present invention are in the form of a fine plate.
Further, an insulated wire having further superior flexibility is obtained when the layer thickness of the first insulating metal oxide layer is 1 to 10 ~m.
In addition, it is also possible to provide an insulated wire comprising a protective coat, by coating the outer side of the second insulating metal oxide layer with an insulating material containing an organic material.
The conductor is not particularly restricted so far as the same has conductivity, and the configuration, the material etc. thereof may be selected in response to its application such as a thermocouple or a flexible printed circuit, for example.
Since the insulated wire according to the present invention comprises insulating layers of metal oxides having extremely high melting points around the conductor, it is possible to maintain insulation even under a high temperature, as compared with the conventional insulated wire which is coated with heat resistant organic resin.
Further, the insulated wire according to the present invention can be used also under high-vacuum environment, since the same emits no gas.
In the present invention, further, the insulating 205C333~

metal oxide layer can be increased in thickness since the ceramics particles are contained in the insulating metal oxide layer by addition, whereby it is possible to obtain an insulated wire having a high breakdown voltage.
S It is difficult to increase the first insulating metal oxide layer in thickness, and an insulated wire which comprises only the first layer has a low breakdown voltage. However, since the first insulating metal oxide layer is in close contact with the conductor, it is excellent in flexibility and can maintain insulation even if the same is extremely deformed in bending or the like.
On the other hand, the second insulating metal oxide layer has high insulability since the same can be easily increased in thickness by applying a substance obtained by adding ceramics particles to a precursor of ceramics to the conductor and baking the same. If this layer alone is formed around the conductor, however, it may not be possible to maintain good insulation due to fine cracks caused in the layer when the same is extremely deformed in bending or the like, since the layer is inferior in adhesion with the conductor as well as bonding property of particles within the layer to the first insulating metal oxide layer.
Therefore, the aforementioned first layer is formed around the conductor and the aforementioned second layer 33~

is further formed around the firs.t layer, so that fine cracks, that may be caused in the second layer by extreme deformation resulting from bending or the like, are prevented by the first layer, and it is possible to maintain high insulability over the entire insulating layers.
When alkoxides or organic acid salts of Si, Zr, AQ
and Ti are employed as materials for the first and/or second insulating metal oxide layer, it is possible to form homogeneous insulating layer(s) by preparing a precursor of an oxide from these solutions using a method such as a sol-gel method or a thermal decomposition method, applying this precursor to the periphery of the conductor, and further carrying out baking.
Further, when the ceramics particles which are contained in the second insulating metal oxide layer by addition in advance of application are in the form of a fine plate, it is possible to obtain an insulated wire having a higher breakdown voltage.
Further, if the thickness of the first insulating metal oxide layer is l to 10 ~m, it is possible to obtain an insulated wire having further superior flexibility.
In addition, it is also possible to use the wire as a fireproof wire by providing a protective coat which contains an organic material on the outer side of the second insulating metal oxide layRr.
Brief Description of the Drawings Fig. 1 is a sectional view of an insulated wire in which a first insulating silicon oxide layer of 5 ~m in S thickness and a second insulating metal oxide layer of 35 ~m in thickness are formed around a nickel-plated copper wire of 1 mm in diameter according to the present invention.
Fig. 2 is a sectional view of an insulated wire which is obtained by coating three insulated wires shown in Fig.
1 with polyolefine resin mixed with magnesium hydroxide.
Best Modes for Carrying Out the Invention Example 1 A nickel-plated copper wire of 1 mm in diameter was employed as a conductor.
1 mole percent of nitric acid was added to a mixed solution of 4 mole percent of tetraethoxysilane, ?.4 mole percent of water and 71 mole percent of ethyl alcohol.
This solution was applied to the aforementioned nickel-plated copper wire, and thereafter baking was continuouslycarried out at a temperature of 500~C, to form a first insulating silicon oxide layer of 5 ~m in thickness.
Further, a substance, which was obtained by mixing 2 parts of mica of about 2 ~m in mean particle diameter to 10 parts of a mixed solution of 4 mole percent of 20~339 tetraethoxysilane, 1 mole percent.of tetraethoxyzirconium, 1 mole percent of water and 94 mole percent of ethyl alcohol as ceramics particles, was applied to the periphery of the aforementioned first insulating silicon oxide layer, and thereafter baking was continuously carried out at a temperature of 600~C, to form a second insulating metal oxide layer of 35 ~m in thickness.
Fig. 1 is a sectional view of an insulated wire formed by the aforementioned process.
A first insulating metal oxide layer 13 is formed around a conductor comprising a nickel-plated layer 12 which is formed around copper 11, and a second ins~lating metal oxide layer 14 containing ceramics particles is further formed around the same.
As to a material which was provided with only the first insulating metal oxide layer, a breakdown voltage was measured in the process of formation of such an insulated wire, whereby the result was about 500 V.
Further, a breakdown voltage of an insulated wire which was provided with the second insulating metal oxide layer containing ceramics particles was measured, whereby the result was at least 1200 V.
Thus, it has been clarified that an insulated ~~ire having a high breakdown voltage can be obtained according to the present invention.

-205~i339 Even if the insulated wire formed by the aforementioned process was held under a temperature of 850~C for 30 minutes, insulation was maintained. Thus, it has been clarified that the insulated wire obtained according to the present invention can maintain insulation even under a high temperature.
Example 2 Three insulated wires obtained in Example 1 were employed, and these three wires were coated with polyolefine resin mixed with magnesium hydroxide, to obtain a single wire.
Fig. 2 is a sectional view of the wire thus obtained.
Three insulated wires 21 are gathered and respectively coated with polyolefine resin 22 mixed with magnesium hydroxide, to form a single wire.
This wire continuously served as a wire even if the same was held under a temperature of 850 degrees for 30 minutes.
Industrial Applicability As hereinabove described, the insulated wire according to the present invention can maintain insulation even under a high temperature, is excellent in flexibility, emits no gas, can use various types of conductors, and is advantageously applicable to an insulated wire, a fireproof wire, a thermocouple and a flexible printed circuit etc., for which a high breakdown voltage is required.

Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An insulated wire comprising a conductor, a first insulating metal oxide layer formed around said conductor, and a second insulating metal oxide layer, containing ceramics particles mixed by addition, formed around said first insulating metal oxide layer, wherein said first insulating metal oxide layer and/or said second insulating metal oxide layer is formed by baking a precursor containing at least one compound selected from the group consisting of alkoxides and organic acid salts of Si, Zr, Al and Ti.
2. An insulated wire as defined in claim 1, wherein said ceramics particles are in the form of a fine plate.
3. An insulated wire as defined in claim 1 or 2, wherein the thickness of said first insulating metal oxide layer is within the range of 1 to 10 µm.
4. An insulated wire as defined in claim 1 or 2, further comprising a protective coat, containing an organic material, on the outer side of said second insulating metal oxide layer.
5. An insulated wire as defined in claim 1 or 2, wherein the thickness of said first insulating metal oxide layer is within the range of 1 to 10 µm, the wire further comprising a protective coat, containing an organic material, on the outer side of said second insulating metal oxide layer.
6. An insulated wire for high temperature use, comprising:
an electrical conductor core consisting essentially of copper;

a first insulating metal oxide layer formed around said conductor core and having a thickness of 1 to 10 µm;
and, a second insulating metal oxide layer, containing ceramics particles mixed by addition and formed around said first insulating metal oxide layer;
wherein said first insulating metal oxide and said second insulating metal oxide are selected from the group consisting of oxides of silicon, zirconium, aluminum and titanium obtained by baking at least one compound selected from the group consisting of alkoxides and organic acid salts of Si, Zr, Al and Ti.
7. An insulated wire as defined in claim 6, wherein said first and second insulating metal oxides are oxides of silicon.
8. An insulated wire as defined in claim 6, wherein said ceramics particles are in the form of a fine plate.
9. An insulated wire as defined in claim 6, further comprising a protective coat, containing an organic material, on the outer side of said second insulating metal oxide layer.
CA 2050339 1989-12-27 1990-12-26 Insulated wire for high temperature use Expired - Fee Related CA2050339C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1-343489 1989-12-27
JP34348989A JPH03201311A (en) 1989-12-27 1989-12-27 Insulated electric wire

Publications (2)

Publication Number Publication Date
CA2050339A1 CA2050339A1 (en) 1991-06-28
CA2050339C true CA2050339C (en) 1997-12-02

Family

ID=18361918

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2050339 Expired - Fee Related CA2050339C (en) 1989-12-27 1990-12-26 Insulated wire for high temperature use

Country Status (5)

Country Link
EP (1) EP0460238B1 (en)
JP (1) JPH03201311A (en)
CA (1) CA2050339C (en)
DE (1) DE69033532D1 (en)
WO (1) WO1991010238A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2698937B2 (en) * 1990-11-13 1998-01-19 矢崎総業株式会社 Ceramic coated heat-resistant insulated wire
US7795538B2 (en) 2007-11-06 2010-09-14 Honeywell International Inc. Flexible insulated wires for use in high temperatures and methods of manufacturing
GB0810572D0 (en) 2008-06-10 2008-07-16 Univ Teeside Electrically insulating coating and method
US8680397B2 (en) 2008-11-03 2014-03-25 Honeywell International Inc. Attrition-resistant high temperature insulated wires and methods for the making thereof
GB201308704D0 (en) 2013-05-15 2013-06-26 Rolls Royce Plc Electrical apparatus encapsulant

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53136009A (en) * 1977-05-04 1978-11-28 Riken Keikinzoku Kogyo Kk Aluminium oxide structures
JPS5818809A (en) * 1981-07-24 1983-02-03 株式会社デンソー Overload resistant insulating wire and method of producing same
JPS63281313A (en) * 1987-05-12 1988-11-17 Sumitomo Electric Ind Ltd Heat-resistant electric wire
SE8901788L (en) * 1988-06-14 1989-12-15 Gte Laboratories Inc COMPOSITIVE COATINGS ON ELFABLE SUBSTRATE AND COATING PROCEDURE
JPH02123618A (en) * 1988-11-02 1990-05-11 Opt D D Meruko Lab:Kk Heat resistant insulated electric wire

Also Published As

Publication number Publication date
EP0460238B1 (en) 2000-05-03
EP0460238A1 (en) 1991-12-11
DE69033532D1 (en) 2000-06-08
WO1991010238A1 (en) 1991-07-11
JPH03201311A (en) 1991-09-03
CA2050339A1 (en) 1991-06-28
EP0460238A4 (en) 1992-11-25

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