JPH03245409A - Insulated wire - Google Patents

Abstract

PURPOSE:To obtain a wire having high insulation under a high-temperature environment, excellent flexibility, and no gas adsorption and allowing combinations of base material and inorganic insulation layer suitable for various kinds of use by forming a specific layer on the outer surface of a conductive base body and applying a prescribed precursor solution on this layer to provide an insulated layer. CONSTITUTION:A nickel sulfide layer, or a complex layer of a nickel sulfide layer and a nickel oxide layer is formed on the outer surface of a conductor base material of a copper wire or the like and a precursor solution of a metal oxide is applied to make an insulated layer. Then, an insulated wire having a high-insulating property under high-temperature environment as well as high flexibility while having no gas adsorption property and being able to select combination of a base material suitable for various kinds of use and an inorganic insulated layer, further being suitable to be used for an equipment such as a fire alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to insulated wires, and more particularly to insulated wires such as wiring wires and winding wires used in high-temperature environments.

[Prior Art] Insulated wires are sometimes used in equipment that requires safety under high temperatures, such as heating equipment and fire alarms. Insulated wires are also used in environments that are heated to high temperatures inside automobiles. For such insulated wires,
Conventionally, insulated wires in which the conductor is coated with a heat-resistant organic resin such as polyimide or fluororesin have been discontinued.

When used in applications that require high heat resistance or in environments that require a high degree of vacuum, organic coating alone is insufficient.
It is insufficient in terms of heat resistance, gas release properties, etc. Therefore, we have developed insulated wires in which the conductor is passed through a ceramic insulator tube, and insulated wires in which the conductor is passed through a tube made of a heat-resistant alloy made of stainless steel or other alloy filled with fine particles of metal oxide such as magnesium oxide. Ml cable (Mineral
1 nsulated cable) and the like have been used for such purposes.

Examples of insulated wires that require flexibility as well as heat resistance include glass braided insulated wires that use woven glass fibers as an insulating member.

[Problems to be Solved by the Invention] In an insulated wire coated with a heat-resistant organic resin as described above, the highest temperature at which insulation can be maintained is about 200°C at most. Therefore, it has not been possible to use such organic insulated wires in applications where insulation is required to be guaranteed at high temperatures of 200° C. or higher.

Furthermore, insulated wires whose heat resistance is improved by using ceramic insulator tubes have drawbacks such as poor flexibility.

Since the Ml cable is composed of a heat-resistant alloy tube and a conductor, the outer diameter of the cable is large. Therefore, M
The l cable has a relatively large cross-section compared to the amount of power that the conductor passing through the heat-resistant alloy tube can tolerate. Furthermore, since the outer layer of the M1 cable is made of a heat-resistant alloy tube, it has good flexibility.

However, in order to use the tube as a winding wire that is wound into a coil around a bobbin or the like, it is necessary to bend the tube made of a heat-resistant alloy at a predetermined curvature. At this time, the tube is bent into a tube made of a heat-resistant alloy, and the bending process is difficult. Furthermore, when winding an MI cable into a coil, the outer tube is thicker than the conductor, so it is difficult to improve the winding density.

Furthermore, when using a glass braided insulated wire that is flexible and heat resistant, there is a problem in that glass dust is generated from the glass fibers when the wire is arranged in a predetermined shape depending on the application. This glass dust can be a source of gas adsorption. Therefore, when a glass braided insulated wire is used in an environment that requires a high degree of vacuum, it has been impossible to maintain a high degree of vacuum because of the gas adsorption source provided by the glass dust.

On the other hand, so-called alumite wires, which are aluminum or aluminum alloy wires subjected to anodizing treatment, have conventionally existed as insulated wires with good heat resistance, insulation, and heat dissipation properties. In anodized electric wires, the base material is limited to one type of aluminum. Further, the inorganic insulating layer formed on the base material is also limited to aluminum oxide.

Therefore, there has been a problem in that it is not possible to select combinations of base materials and inorganic insulating layers that are suitable for various uses.

Therefore, the present invention was made to solve the above problems, and an object of the present invention is to provide an insulated wire having the following features.

(a) Must have high insulation properties in high temperature environments.

(b) Excellent flexibility.

(C) Not equipped with a gas adsorption source.

(d) Being able to select combinations of base materials and inorganic insulating layers suitable for various uses.

[Means for Solving the Problems] An insulated wire according to the present invention includes a base material, a nickel sulfide-containing layer, and an oxide insulating layer.

The substrate has an outer surface and includes a conductor. The nickel sulfide-containing layer is a nickel sulfide layer formed on the outer surface of the base material.
and a composite layer including a nickel sulfide layer and a nickel oxide layer.

An oxide insulating layer is formed on the nickel sulfide-containing layer. Among the nickel sulfide layer and the composite layer including the nickel sulfide layer and the nickel oxide layer, any nickel sulfide-containing layer is preferably formed by an electrochemical method. Here, the electrochemical method refers to, for example, an electrolytic plating method. The base layer on which the oxide insulating layer is applied may be nickel sulfide or a base layer whose surface has been oxidized to form an oxide in order to function preferably as an adhesion layer. The base material is preferably made of copper or a copper alloy from the viewpoint of high conductivity and cost reduction.

[Operations and Effects of the Invention] It is known that a chrome plating layer is formed as a good adhesion layer on a conductor such as copper or a copper alloy. However, insulating oxide ceramics such as silicon oxide produced by the sol-gel process rarely exhibit adhesion to nickel plating layers.

This is based on the knowledge of the inventors of the present application.

Furthermore, in an insulated wire in which a ceramic thin film is directly formed on the surface of a conductor made of copper, the adhesion of the ceramic thin film functioning as an insulating layer to the base material is insufficient. For example, when a thin film of silicon oxide is formed on a base material made of copper by chemical vapor deposition (CVD), the thin film may peel off even if rubbed by hand.

This is based on the findings of the inventors of the present application.

Therefore, in the present invention, a layer having a nickel sulfide layer as the outermost layer is formed on the outer surface of the base material. On top of this nickel sulfide layer is an insulating oxide ceramic.
Adheres as a layer with good adhesion.

The nickel sulfide layer can be formed by an electrochemical method such as electroplating.

This nickel sulfide layer forms a black surface layer with many irregularities, depending on the plating conditions. Further, since an oxide layer is formed around the nickel sulfide layer, in order to obtain higher adhesion, the surface of the nickel sulfide layer may be changed into an oxide by heat treatment in advance.

Further, in order to prevent oxidation of the surface of the base material, at least one of nickel, chromium, and silver is added to the surface of the base material.
The various metal layers may be formed by electrolytic plating.

In this invention, an insulating oxide layer is formed by applying a metal oxide precursor solution onto the nickel sulfide-containing layer. The metal oxide precursor solution referred to in this specification is a solution prepared from a metal organic compound, and includes the following two types.

The first type of precursor solution is a solution produced by subjecting a compound containing a hydrolyzable metal-oxygen-organic group bond, such as a metal alkoxide and metal acetate, to a hydrolysis reaction and a dehydration condensation reaction. This solution may contain an organic solution such as alcohol, a raw material compound such as metal alkoxide, water and a catalyst necessary for the hydrolysis reaction. Furthermore, unlike hydroxide sol produced from inorganic salts, it often contains organic residues such as alkoxides.

The second type of precursor solution is a solution in which an organic metal compound such as an organic acid salt of a metal is dissolved in a suitable solvent.

In a method using this type of precursor solution, a metal oxide is generated by heating and thermal decomposition after application.

Therefore, the decomposition temperature of the metal organic compound used must be lower than its boiling point or sublimation point.

Note that the metal organic compound referred to in this specification is, for example, J
our own of materials 5c
ience 12 (1977) 1203-1208
"mental-organic c" described on page
This is a similar concept to 'impounds'.

Furthermore, the coating layer needs to be left at a temperature higher than room temperature in order to volatilize the organic solvent and remove residual organic substances. However, the temperature of the atmosphere in which it is left must not be higher than the melting point of the metal constituting the base material.

The oxide insulating layer formed from the metal oxide precursor solution is a ceramicized oxide.

This oxide is preferably formed by heat treatment in an atmosphere of oxygen flow. The decomposition of the compound contained in the solution applied onto the nickel sulfide-containing layer is completely completed at a temperature of about 500°C. However, when heat-treated at a temperature higher than that, the reaction between the metal constituting the nickel sulfide-containing layer and the metal or metalloid contained in the applied solution is promoted.
The adhesion between the nickel sulfide-containing layer and the oxide insulating layer is improved.

In this way, the ceramic oxide insulating layer exhibits excellent heat-resistant insulation even at high temperatures of 500° C. or higher. In addition, the nickel sulfide-containing layer has excellent adhesion to the conductor constituting the base material.

Therefore, compared to forming an oxide insulating layer by applying a metal oxide precursor solution directly to the outer surface of the conductor, the adhesion between the oxide insulating layer and the outer surface of the base material is improved. do.

Therefore, the insulated wire provided by this invention is
It has heat-resistant insulation and good flexibility.

Furthermore, the oxide insulating layer formed on the nickel sulfide-containing layer has a smooth outer surface. Therefore, it is possible to obtain a high dielectric breakdown voltage proportional to the film thickness, and to reduce the number of gas adsorption sources.

Further, in the present invention, a nickel sulfide-containing layer is formed between the base material and the oxide insulating layer. For this reason,
Via the nickel sulfide-containing layer, combinations of base material and inorganic insulating layer suitable for various applications can be selected.

Note that since a method using a solution is used to form the insulating layer, it is possible to coat a linear base material with simple equipment and at high speed.

[Example] Example 1 Nickel sulfate 75g/L Nickel ammonium Meikai 45
g/L zinc sulfate 38g/L, and Rodan soda 15g
A copper wire with a wire diameter of 1゜Ommφ is immersed as a base material in an electrolytic bath with a current density of 2OA/fL, and this base material is used as a cathode.
Nickel sulfide plating was performed at dm2 and bath temperature of 55°C to form a nickel sulfide plating layer on the outer surface of the base copper wire.

To a solution of 10 mol% zirconium butoxide and 20 mol% ethanolamine in n-butanol, 2.1 times the mol of water relative to the zirconium butoxide diluted with diethylene glycol monomethyl ether was added, and to this was added natural mica (with an average particle size of 5 μm). A coating solution was prepared by mixing 10% by weight of mica powder). This coating solution was applied onto the copper wire on which the nickel sulfide plating layer was formed and fired to form a mica-zirconia composite inorganic insulating layer. Firing was performed at 500° C. in the air.

FIG. 1 is a cross-sectional view of the insulated wire obtained as described above. Referring to FIG. 1, a nickel sulfide layer 2 is formed on a base material 1 which is a copper wire, and a mica◆zirconia composite inorganic insulating layer 3 is formed on this nickel sulfide layer 2. There is.

A sample with a length of 30 cm was taken from the obtained insulated wire. Platinum foil with a thickness of 0.02 mm was tightly wrapped around a length of about 10 mm at four locations with an interval of about 50 mm, and when a 60 Hz AC voltage was applied between the conductor and the metal foil, the voltage was 15 kV. Dielectric breakdown occurred.

This insulated wire was held at a temperature of 300 DEG C. for 10 minutes in an atmosphere with a vacuum degree of 1X10-' Torr, and then cooled to room temperature, which was a heating cycle performed 10 times. When the insulated wire was subjected to a dielectric breakdown test after this heating cycle, a dielectric breakdown voltage of 15 kV was maintained.

Further, this insulated wire was wound around a cylinder having a diameter of 20 mm, and then the cylinder was pulled out to form a coil shape.

When a dielectric breakdown voltage was measured using this coiled insulated wire, a dielectric breakdown voltage of 15 kV was maintained.

As is clear from the above cases, the insulated wire of the embodiment according to the present invention has high insulation properties even in a high temperature environment and is excellent in flexibility.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment according to the present invention. In the figure, 1 is a base material, 2 is a nickel sulfide layer, and 3 is a mica-zirconia composite inorganic insulating layer.

Claims (6)

[Claims] (1) Any one of a base material having an outer surface and containing a conductor, a nickel sulfide layer, and a composite layer containing a nickel oxide layer and a nickel sulfide layer formed on the outer surface of the base material. An insulated wire comprising: a nickel sulfide-containing layer; and an oxide insulating layer formed by applying a metal oxide precursor solution on the nickel sulfide-containing layer. (2) The insulated wire according to claim 1, wherein the nickel sulfide layer is formed by electrolytic plating. (3) The insulated wire according to claim 1, wherein the composite layer is formed by oxidizing a nickel sulfide layer formed by electrolytic plating. (4) The insulated wire according to claim 1, wherein the oxide insulating layer contains at least one of silicon oxide and aluminum oxide. (5) The insulated wire according to claim 1, wherein the base material includes either copper or a copper alloy. (6) The insulated wire according to claim 1, wherein the base material has a layer of at least one of nickel, chromium, and silver applied on the surface by electrolytic plating.