JPH03241612A - Heat resisting insulated wire - Google Patents

Abstract

PURPOSE:To obtain an insulated wire having excellent heat resistance by forming an insulated and coated layer, in which coating varnish having inorganic short fibers as a filler while having a polychromic acid compound and a phosphoric acid compound as binders is applied to the surface of a conductor having good conductivity followed by baking treatment. CONSTITUTION:When coating varnish containing a polychromic acid compound and a phosphoric acid or phosphoric acid group compound as binders is used for being applied to the surface of a conductor of good conductivity and baked as well, the coating varnish is fired and a ceramic layer as an insulated and coated layer is formed. Since coating varnish contains inorganic short fibers as a filler, a fired ceramic layer is of structure having interwined inorganic short fibers. Thereby, weakening of the ceramic layer is prevented and a coating layer strong and having good flexibility is formed while preventing cracks and falling-off of the ceramic layer inspite of heating after being mounted on an electric equipment so that heat resistance can be improved without damaging insulation. When selection is made to make short fibers 5 to 30mum long and a diameter 0.2 to 1.0mum wide, a good finished surface having no surface roughness at the time of application to the conductor and baking can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-resistant insulated wire that is used for coils of electrical equipment, etc., and has excellent resistance to thermal deterioration.

[Conventional technology]

Conventionally, magnet wires, transformer coils,
Insulated wires used as windings for motor coils, generator coils, etc. include formal, nylon, polyurethane,
Enameled wires are commonly used, which are made by coating and baking an insulating varnish containing an organic resin such as polyester on the surface of a copper wire.

Furthermore, as insulated wires for signal cables, vinyl wires in which a copper wire is coated with vinyl chloride resin or the like by injection molding are commonly used.

[Problem to be solved by the invention]

However, in recent years, the demand for smaller and lighter communication equipment has led to an increase in the temperature within the equipment, so it is strongly desired to improve the heat resistance of insulated wires used within the equipment.

Conventional heat-resistant insulated wires are generally made by coating the surface of copper wire with polyimide enamel paint, which has the highest heat resistance among the enamel paints used industrially. However, polyimide is essentially carbon,
Since it is an organic substance with skeletons of hydrogen, oxygen, and nitrogen,
Heat resistance is not sufficient at high temperatures of 250'c or higher.

Additionally, a ceramic enamelled wire made of 100% inorganic material has been proposed in order to have heat resistance of around 300°C, but this has not been put into practical use because its flexibility and dielectric breakdown voltage characteristics are significantly inferior. .

In addition, for ceramic enamelled wire that retains its flexibility only during the winding work of electrical equipment coils, for example, an inorganic powder insulating material such as enamel frit, which can be converted into ceramic at high temperatures, is added to an organic material binder such as silicone paint. There is also ceramic conversion enamelled wire, which is made by blending, applying the blended paint to the surface of the copper wire, and baking it, but this is done by applying an organic material binder at a high temperature of 400°C to 800°C after completing the coil winding work. There is the trouble of having to ash the inorganic powder insulating material and converting it into ceramic.

In addition, in order to eliminate the trouble of performing ceramic conversion after the winding work is completed, a mixture of an organic material binder and a metal oxide powder insulating material such as aluminum oxide or aluminum hydroxide is applied onto the conductor. , enamelled wires that are baked to form a ceramic layer have also been developed;
In this case, the adhesiveness of the binder decreases at high temperatures and the ceramic layer becomes brittle, so in the high temperature range of 200°C to 300°C or higher, the ceramic layer may crack or peel due to the difference in expansion coefficient between the metal oxide powder and the conductor. There was a drawback that the insulation properties were impaired due to drop-off.

Therefore, the present invention aims to solve the technical problem of providing a ceramic layer on a conductor that does not crack or peel off even at high temperatures of 500°C, and to improve the quality of heat-resistant insulated wires. purpose.

[Means to solve the problem]

In order to solve this problem, the present invention applies a paint containing inorganic short fibers as a filler and a dichromate compound and phosphoric acid or a phosphoric acid compound as a binder to the surface of a conductor with good conductivity. It is characterized by an insulating coating layer formed by coating and baking.

[Action of the invention]

According to the present invention, a paint containing a dichromate compound and phosphoric acid or a phosphoric acid compound as a binder is used, and when this is applied to the surface of a conductor with good conductivity and baked, the paint is baked. A ceramic layer is formed as an insulating coating layer.

Further, since the paint contains inorganic short fibers as a filler, the fired ceramic layer has a structure in which the inorganic short fibers are entangled.

This prevents the ceramic layer from becoming brittle and forms a strong and flexible coating layer, preventing the ceramic layer from cracking or peeling off and providing insulation even when heated after being installed in electrical equipment. Heat resistance can be improved without impairing properties.

In addition, the length of the inorganic short fibers is 5 to 30 μm, and the diameter is 0.2 μm.
If the thickness is selected to be 1.0 μm, a good finished surface without roughness can be obtained when the conductor is coated and baked.

Furthermore, by forming an insulating coating layer on the surface of the conductor by baking, and then forming an outermost layer made of a resin with excellent heat resistance, flexibility, and electrical insulation, the surface will become smoother. , the winding workability of insulated wires can be significantly improved.

〔Example〕

First, 25 parts of magnesium dichromate, 30 parts of phosphoric acid or trimethyl phosphate, and inorganic short fibers (for example, 9 A 7!zO+2 B2O3, length 10-20 μm
, 0.5 μm in diameter) to create an inorganic paint, apply this paint to a nickel-plated copper wire with a diameter of 1I11, and then immediately dry and bake it at 200 to 300 ° C several times. An insulating coating layer of about 25 μm was formed on the surface of the copper wire to obtain an insulated wire.

The dry baking temperature is set to K in order to give flexibility to the insulation coating layer.
2O0 to 300°C is preferable, and if baking is performed at a temperature higher than this, sintering of the coating layer will proceed, resulting in lower flexibility than when baking is performed at a high temperature.

In addition, if the inorganic short fibers mixed in the inorganic paint are too short, the bond between the fibers will be weak and the coating layer will become brittle, and if it is too long, not only will the surface of the coating layer become rough, but the coating layer will also be damaged. Since there is a problem that it becomes thick and easily cracks, it is desirable that the thickness be within about 10 to 30 μm.

Among the insulated wires manufactured by the above method, those coated with only inorganic paint and baked have a dielectric strength voltage of 10 kV of the insulation coating layer.
As described above, the volume resistivity was 10"Ω·Cl11 or more, and the hardness (pencil hardness) was 5H or more.

In addition, the curvature has an excellent property that even if the wire is bent to a diameter (6 mrn) that is approximately six times the diameter of the insulated wire (1 mm), the insulation coating layer will not crack or peel off, and the dielectric strength voltage will not deteriorate. was gotten.

Thereafter, by heating at 500° C. for 200 hours, the insulating coating layer became even stronger, and the dielectric strength was improved to 12 kV or more and the volume resistivity to 10'4 Ω·cm or more.

This is because when insulated wires are used as coils in electrical equipment, the wire temperature rises due to short-term overcurrent flow, which strengthens the bonding of inorganic components in the coating layer, improving heat resistance. It shows that.

Further, a nylon resin varnish was further applied on the 25 μm thick inorganic coating layer, and then dried and baked to form a nylon coating layer with a thickness of, for example, 3 μm on the outer peripheral surface as the outermost layer.

The curvature of this wA electric wire was improved from six times the diameter of the insulated wire (6 mm) to three times the diameter (3 mm) compared to the case where no outermost layer was provided.

In addition, the nylon coating layer on the surface has a very thin thickness of 3 μm, so the surface is smooth and slippery, and has good flexibility, so wrapping the insulated wires can significantly improve workability. It has the advantage of being able to

Furthermore, when the nylon coating layer formed on the insulated wire is electrically heated and calcined at about 300° C., it is thermally decomposed and the bonding of the inorganic short fiber composite layer below it is strengthened.

In addition, as the inorganic short fiber used as a filler, 9
In addition to Aβzot2Bzoa, A20 with high electrical resistance
3. Si, N4,5iOz, MgO or K2O・6T
Short fibers such as iO□ may also be used.

In addition, good conductors include not only nickel-coated copper wire, but also stainless steel and chrome.

Copper wire coated with silver, silver wire, gold wire, platinum wire.

A Cu-Ni alloy wire or the like may also be used. In addition, when used in applications where heat resistance conditions are not so strict, a wire body made only of ordinary electrolytic copper may be used, and an inorganic paint may be directly applied thereto and baked.

[Comparative example]

A polyimide varnish was applied to a nickel-plated copper wire having a diameter of 1 mm and dried to form an insulating coating of 30 μm.

This insulated wire has a dielectric strength voltage of 12 kV or more, an electrical volume resistivity of 10'4 Ω·cm or more, and a hardness (pencil hardness) of 5H or more, and its electrical and mechanical properties are the same as those of the above example. Inferior to Examples in heat resistance. That is, 5
When heated at 00°C for 200 hours, the coating layer thermally decomposed (degraded) and lost its electrical insulation properties.

Therefore, it can withstand use if it is not overheated when energized, but it can withstand use when it is energized and overheated, such as in ignition coils, or when coils and transformers are used in high temperatures. , causing failure.

On the other hand, even when the heat-resistant insulated wire of the present invention is energized and overheated, the insulation coating layer does not thermally decompose (degrade).
Since the insulation is maintained without any damage, no breakdown occurs.

〔Effect of the invention〕

As described above, according to the present invention, even if the insulating coating layer formed on the conductor surface is left in a high temperature of 500°C for a long time, the inorganic short fibers will not become entangled and cause cracking or peeling. Further, since there is no reduction in dielectric strength voltage caused by this, it has the excellent effect of being able to provide a high quality insulated wire with excellent heat resistance.

Claims (6)

[Claims] (1) An insulating coating made by applying and baking a paint containing inorganic short fibers as a filler and a dichromate compound and phosphoric acid or a phosphoric acid compound as a binder to the surface of a conductor with good conductivity. A heat-resistant insulated wire characterized by having a layer formed thereon. (2) The inorganic short fibers have a length of 5 to 30 μm and a diameter of 0.
．． The heat-resistant insulated wire according to claim 1, which has a thickness of 2 to 1.0 μm. (3) The inorganic short fibers are 9Al_2O_32B_2
O_3, Al_2O_3, Si_3N_4, SiO_2
, MgO or K_2O.6TiO_2 according to claim 1. (4) The heat-resistant insulated wire according to claim 1, wherein the conductor having good conductivity is a filament of copper, copper alloy, or silver. (5) The heat-resistant insulation according to claim 1, wherein the conductor having good conductivity has a structure in which the surface of a filament made of copper, copper alloy, or silver is coated with nickel, chromium, or stainless steel. Electrical wire. (6) An insulating coating layer formed by applying and baking a paint containing inorganic short fibers as a filler and a dichromate compound and phosphoric acid or a phosphoric acid compound as a binder to the surface of a conductor with good conductivity. 1. A heat-resistant insulated wire, characterized in that the outermost layer is formed on the outer peripheral surface of the resin and is made of a resin having excellent heat resistance, flexibility, and electrical insulation.