JPS5914842B2 - Heat resistant magnet wire - Google Patents

Description

[Detailed Description of the Invention] This invention relates to heat-resistant insulated wires used for winding of electrical equipment;
In other words, it relates to so-called heat-resistant magnet wire for winding, which can normally be used in the same way as conventional 10-winding enamel wire, but also forms a ceramic insulating layer at high temperatures, making it possible to use it continuously at high temperatures. be.

Recently, insulated wires in which a conductor is coated with highly heat-resistant ceramic have come to be used as heat-resistant magnet wires for winding.

However, ceramics are usually extremely hard and brittle;
Ceramic-coated electric wires have extremely poor flexibility and are difficult to form, such as bending, and as a result, their range of use is limited. Furthermore, due to the lack of flexibility as mentioned above, cracks occur in the ceramic insulation coating over long periods of use due to vibrations during handling and use, and as a result, heat shock during use causes metal conductors to crack. The adhesion with the ceramic insulation coating was poor, resulting in the ceramic insulation coating sometimes peeling off, and therefore the heat resistance and insulation properties were still unsatisfactory. By the way, depending on the type of electrical equipment that uses the magnet wire and its usage conditions, the temperature may not reach a high enough temperature to require a 30 ceramic insulation coating under normal conditions, but the temperature may rise or abnormalities may occur due to the intermittent application of a large load. There are cases where ceramic coating is required only when the temperature reaches a high temperature, but in the past, ordinary ceramic insulated 35 wire was used even under such conditions, so the problem mentioned above cannot be avoided. It was hot.

Therefore, the inventors of the present invention proceeded with the development of a heat-resistant magnet wire that could skillfully meet the above-mentioned conditions. It exhibits mechanical and electrical properties similar to conventional organic enamel insulated wires during wire processing and at normal operating temperatures close to room temperature, and only exhibits the characteristics of ceramic insulated wires at abnormally high temperatures. This was the first successful development of heat-resistant magnet wire.
In other words, the heat-resistant magnet wire obtained by the proposed manufacturing method has a composite coating layer of a mixture of inorganic fine powder and silicone resin (or a mixture of inorganic fine powder, silicone resin, and other resins) on the conductor. formed,
A flexible protective resin layer is formed on this composite coating layer, and a ceramic insulating layer is formed at high temperatures. Since the composite coating layer of this heat-resistant magnet wire has not been made into ceramic through artificial firing heat treatment, the composite coating layer and the resin layer on it are highly flexible during the winding process. In addition, even if friction between wires or friction against objects occurs, the presence of the resin layer prevents the composite coating layer from peeling off, so it can be processed in the same way as ordinary organic enamel insulated wires.
Furthermore, under normal usage conditions below the heat resistance temperature of the resin in the composite coating layer, it exhibits the same electrical and mechanical properties as ordinary organic enamel insulation, but when exposed to high temperatures above the heat resistance temperature of the resin during abnormal conditions. In cases where a low temperature state below the heat-resistant temperature of the resin and a high-temperature state above the heat-resistant temperature are repeated, the composite coating layer will turn into a ceramic without causing a sudden or temporary decline in electrical properties and will remain as it is. It can be used continuously from low to high temperatures. However, upon further study of the heat-resistant magnet wire proposed above, it was found that the following problems existed.

In other words, in the composite coating layer coated on the conductor of the electric wire proposed above, silicone resin (or modified silicone resin, or a mixture of silicone resin and other resins) acts as a binder for the inorganic powder particles. However, during the winding process, the binder resin between the inorganic powder particles in the composite coating layer located outside the wrapping circumference is stretched, but at this time, the composite coating layer and the overcoat formed on it are stretched. If the coating resin layer is bonded to the coating resin layer, that is, if both layers are formed in a continuous state, the binder resin in the composite coating layer cannot withstand the elongation between the inorganic powder particles, causing cracks in the binder resin. If this occurs, there is a risk that cracks may occur in the overcoat resin as well.
For this reason, there is a problem that the winding workability is reduced. In order to solve this problem, it is necessary to select a resin to be used for the overcoat resin layer that has significantly better elongation properties and is stronger than the binder resin such as silicone resin of the composite coating layer. There is a risk that you will not be able to use the most appropriate resin.

In addition, if the composite coating layer and the overcoat resin layer thereon are bonded together as described above, when the binder resin of the composite coating layer decomposes at high temperatures such as during abnormal times, the presence of the overcoat resin layer will cause decomposed gas to be released. The release of
Since it becomes difficult to release the decomposed gas, when the decomposed gas is rapidly heated to a high temperature, the pressure of the decomposed gas from inside rises rapidly, and the overcoat resin layer and composite coating layer are locally blown away. There are problems such as short circuit between lines due to exposure of wires. The purpose of this invention is to improve the above-mentioned proposal so as to simultaneously solve the above-mentioned problem of winding workability and problem of high-temperature heating.
The gist of this is that the composite coating layer formed on the conductor, that is, the composite coating layer that becomes ceramic at high temperatures, is in a floating state or almost non-adhesive state with respect to the composite coating layer. A state in which the straw is only partially adhered or can be easily peeled off from the composite coating layer (hereinafter in this specification, these states will be referred to as a non-adhesive state).

) is formed with a protective resin layer, thereby solving the above-mentioned problems. Specifically, the heat-resistant magnet wire of the present invention includes 100 parts by weight of an inorganic fine powder with a particle size of 10 ttm or less that does not melt or melt near the decomposition temperature of silicone resin and has excellent electrical properties. A composite coating layer of a mixture consisting of 10 to 200 parts by weight of silicone resin is formed, and a flexible resin layer is provided on the composite coating layer in a non-adhesive state to the composite coating layer. It is sometimes characterized by the formation of a ceramic insulating layer. Hereinafter, the heat-resistant magnet wire of the present invention will be explained in more detail.

First of all, the silicone resin used in the composite coating layer of the insulated wire of the present invention acts as a binder for the composite coating layer, and the substance produced after decomposition when fired at high temperatures such as during abnormal times acts as a binder of inorganic powder. It acts as a ceramic layer and produces a stronger ceramic layer. Here, silicone resins include not only ordinary ones but also copolymers of silicone resins and other organic monomers such as methyl methacrylate and acrylonitrile, or copolymers of silicone resins and alkyd resins, phenolic resins, epoxy resins, melamine resins, etc. Contains modified silicone resin such as copolymer. Moreover, one type of silicone resin may be used alone, or a plurality of types may be used in combination. Furthermore, Si(5Ti,B,A1,P,Ge,A
Polymers with one or more elements such as s, Sb, etc. and oxygen in the skeleton, or Si(5T1, B, AI, P, Ge, A
A polymer having one or more elements such as s and Sb, oxygen, and carbon in its skeleton, or a copolymer of these with an organic monomer or resin may be mixed with the silicone resin as described above. Among silicone resins, preferred are inorganic polymers that have excellent flexibility and whose hydrocarbon groups gradually decompose above the heat-resistant temperature, such as methyl-phenyl silicone, which have two or more types of groups with different decomposition temperatures. Silicone resin is good. However, in the case of the present invention, the resin layer is
Even if silicone resins such as dimethyl silicone are easily decomposed, they are provided in a non-adhesive state to the composite coating layer, so even if the temperature rises rapidly to high temperatures, the composite coating layer may stretch or peel. There is no such thing. Further, as the binder for the composite coating layer, the silicone resin described above may be used alone, but in particular, considering mechanical strength etc., other resins such as epoxy resin, polycarbonate, etc. may be used in addition to the silicone resin.
It is also possible to use a mixture of phenolic resins and the like. On the other hand, as the inorganic fine powder, it is necessary to use an inorganic fine powder that is half-melted or does not melt near the decomposition temperature of the silicone resin used as the binder and has excellent electrical properties. For example, crystalline powder, vitreous powder or mixed powder thereof are used, more specifically alumina (
M2O3), barium titanate (BaTiO3), zircon (ZrSlO4), steatite (MgSiO3)
, silica (SiO2), beryllia (BeO), magnesia (MgO), clay, oxides such as high melting point glass frit, nitrides such as boron nitrite (BN), or mixtures thereof. These inorganic fine powders must have a particle size of 10 μm or less.

The reason is as follows. In other words, winding wires for electrical equipment generally require high dimensional accuracy because they are wound onto reel frames of a fixed length, but when coarse grains exceeding 10 μm are used, the thickness of the entire coating layer cannot be precisely controlled. As a result, high dimensional accuracy of the outer diameter cannot be obtained, making it unsuitable for use as a winding wire. In addition, when coarse inorganic powder exceeding 10 μm is used, the surface of the coating layer (the surface of the overcoat resin layer to be described later) becomes more uneven, making it difficult to avoid scratches when winding it around a winding frame or installing the winding wire into equipment. As a result, there is a risk that the coating layer will be torn due to rubbing and the conductor will be exposed. On the other hand, if a fine powder of 10 ttm or less is used as the inorganic powder, it is possible to obtain a magnet wire suitable for winding, which has high dimensional accuracy and is resistant to abrasion, without causing the above-mentioned problems. In addition, the particle size distribution of the inorganic powder may be uniform, but it may also be in a state in which large-diameter particles are well combined so that the composite coating layer has a structure as dense as possible. A fibrous material may also be used. The mixture of inorganic powder and silicone resin, or the mixture of inorganic powder, silicone resin, and other resin that forms the composite coating layer may contain too little binder of silicone resin or other resin relative to the inorganic powder. The lack of flexibility in the coating layer makes coil winding difficult, and conversely, if there is too much binder, a large amount of gas will be generated as the binder resin decomposes when rapidly heated to high temperatures during use. This may cause problems such as the coating layer being blown off, and as a result, the electrical properties (insulating properties) at high temperatures may deteriorate. For these reasons, the blending ratio of the mixture is 10 to 200 parts by weight of silicone resin to 100 parts by weight of inorganic powder.
The amount is determined to be 20 to 60 parts by weight, preferably 20 to 60 parts by weight. In order to form the above-mentioned composite coating layer on the conductor, the mixture may be extruded and coated on the conductor, or the mixture may be added with a diluent in an amount of 20 to 300 parts by weight per 100 parts by weight of the inorganic powder. It is also possible to add about parts by weight to form a solution and coat the conductor with this solution. In the latter case, the diluent may be a reactive or unreactive polysiloxane with a lower viscosity than silicone resin, various modified siloxanes, other inorganic polymers or low polymers that can be thermally decomposed to produce electrically insulating residues. For example, organic polymers such as organic polymers or organic solvents such as xylene and toluene are used. Further, although it is usually desirable that the mixture coated or extruded onto the conductor be cured by heating (including a semi-cured state), it may be left in an uncured state in some cases. This coating layer may be applied in a single layer or in multiple layers, and in some cases, a thin layer of silicone resin or a mixture of silicone resin and other resins used in the composite coating layer may be applied directly on the conductor. A thin layer may be formed and the composite coating layer may be formed on the thin layer.

In such a configuration, the binder component in the composite coating layer is thinly interposed between the composite coating layer and the conductor, so the composite coating layer is firmly bonded to the conductor, improving wear resistance and flexibility. Furthermore, if the composite coating layer becomes ceramic due to exposure to high temperatures during use of the insulated winding, the decomposition products of the thin layer remain as a binder between the conductor surface and the ceramic layer.
In this case as well, wear resistance is improved.

Note that the thickness of the thin layer is preferably about 1 to 5 μm; if it is thicker than this, there is a risk that many pinholes will occur due to foaming when the decomposed gas escapes when the thin layer of silicone resin etc. decomposes due to high temperature. There is. Furthermore, in some cases, the above-mentioned thin layer is formed directly on the conductor, the above-mentioned composite coating layer is formed on the thin layer, and the above-mentioned similar thin layer is formed again on the composite coating layer. Alternatively, a plurality of the thin layers and composite coating layers may be alternately formed. Furthermore, it is desirable that the thickness of the composite coating layer is 5 to 100 μm. If the thickness is less than 5 μm, if the composite coating layer becomes ceramic due to being heated to high temperature during use, the thickness of the ceramic layer will be insufficient and the high temperature If the thickness exceeds 100 μm, the flexibility decreases and the composite coating layer becomes soft, resulting in a decrease in wear resistance.

Conductors coated or extruded with a composite coating layer include plated copper wires made of heat-resistant metals and alloys such as nickel and silver, nickel clad copper wires, stainless steel clad copper wires, silver wires, silver alloy wires, and platinum wires. It is desirable to use heat-resistant conductors such as wire, gold wire, nichrome wire, etc.; however, when exposed to high temperatures for only a short period of time or when used in a non-oxidizing atmosphere, use copper wire or aluminum wire. , aluminum alloy wire can be used. A protective resin layer is overcoated on the composite coating layer as described above in a non-adhesive state to the composite coating layer. The overcoat resin layer formed in this way is intended to satisfy both processability such as winding and properties at high temperatures.First of all, from the viewpoint of processing properties, friction between wires during coil winding etc. This is to prevent the composite coating layer from peeling off due to friction and object friction, and to improve the winding processing characteristics.
More specifically, it is desirable to have excellent flexibility and abrasion resistance that can sufficiently withstand coil winding processing. On the other hand, in terms of heat resistance, it is heat resistant enough to withstand long-term use at normal operating temperatures, and especially when used under conditions where the temperature rises rapidly during abnormal conditions. It is desirable to use a heat-resistant resin with excellent heat-softening properties, such as polyimide, amide-imide resin, esterimide resin, polyhydantoin, heat-resistant polyester, and polyparabanic acid. On the other hand, when the temperature does not rise rapidly as mentioned above, in other words, when the temperature rises intermittent or slowly, urethane resin, fluorine resin, polyolefin, polyamide, formal resin, etc. etc. can be used. The thickness of the overcoat resin layer is preferably 1 to 100 μm. If it is less than 1 μm, it is weak against friction during coil winding, and if it exceeds 100/Tm, the ceramic layer may peel off during decomposition if the resin has poor decomposability, and the space factor Problems such as a decrease in the number of units occur. Moreover, this overcoat resin layer is not limited to one layer, but can be formed into multiple layers depending on the intended use of the electric wire, or may be formed into multiple layers by combining various other resins. For example, if heat softening properties and wear resistance properties are required, first coat with a polyimide etc. with excellent heat resistance properties, then coat with a material with excellent mechanical properties such as polyamideimide, formal resin, polyamide etc. It is desirable to have a multilayer structure. As mentioned above, in order to form the overcoat resin layer on the composite coating layer in a non-adhesive state, it is necessary to use a resin for the overcoat layer that has poor adhesion to the composite coating layer, such as a silicone resin for the composite coating layer. On the other hand, it is preferable to use polyimide, Teflon, amide-imide resin, etc., which have poor adhesion, and coat this resin on the coating layer, or coat it while applying a tensile force to the wire core.

Alternatively, fine powders with lubricating properties such as BN, MOS2, MOS3, WS2, PbOl, silicon nitride, graphite fluoride, graphite, mica, and other inorganic substances or fluororesin and other organic substances may be placed on the composite coating in advance, either as is or mixed with a binder resin. The overcoat resin is then coated, rolled, chewed, or extruded over the coated resin.
Furthermore, the overcoat resin layer may be formed by winding or vertically attaching a tape-shaped piece of the resin. In this case, the overcoat resin tape can be formed by adjusting the tension when winding the tape. Make sure not to tighten it too hard on the coating layer, or use something like wart tape. Furthermore, in the case of such tape winding, the overlapping portions of the tapes may be adhered by various methods as necessary. Also, using a hollow tube-like material as an over-flattened resin layer,
This tube may be extrapolated to the outside of the composite coating layer.
In some cases, another layer that is non-adhesive to at least one of these layers may be interposed between the composite coating layer and the overcoat resin layer to form a composite overcoat resin layer. It may be in a non-adhesive state to the coating layer. Note that on the overcoat resin layer formed as described above,
In order to improve the sliding properties of wires during wrapping, etc.
An antifriction layer of a material that provides lubricity may also be provided. When heat-resistant magnet wires such as those described in detail above are used in electrical equipment, coil winding is usually performed, but the composite coating layer is not made of ceramic, so it is possible to This work can be done easily because it is highly flexible.

Moreover, since the flexible overcoat resin layer provided on this composite coating layer is formed in a non-adhesive state to the composite coating layer, the composite coating layer on the outside of the radius of curvature is Even when the overcoat resin layer is stretched, the overcoat resin layer is stretched independently (with respect to the composite coating layer), so even if a crack occurs in the composite coating layer, the overcoat resin layer will be deformed by the amount that the resin itself deforms. No cracks will occur within the deformation limit.

Therefore, the workability of the electric wire as a whole is extremely good, and it can be wound into a small diameter coil in the same manner as conventional organic enamel insulated electric wires. In addition, even if the overcoat resin layer is made of a resin that does not have high elongation properties or toughness compared to the case where the overcoat resin layer is bonded to the composite coating layer, good processability can be obtained as described above. There is a wide range of selection of resin layers, so the most suitable resin can be used depending on the purpose of use. Note that the presence of the overcoat resin layer prevents the composite coating layer from being directly exposed to the outside surface, so there is no risk of the composite coating layer peeling off due to friction between wires or friction against an object during processing such as coil winding. Never. When the winding made of the magnet wire of this invention is used at a temperature close to normal temperature, which is below the heat resistance temperature of the silicone resin or overcoat resin of the composite coating layer, the composite coating layer is not ceramicized. Moreover, since the overcoat resin layer remains on top of the overcoat resin layer, its mechanical properties are similar to conventional organic enamel insulated wires, so even when used under conditions of mechanical vibration, the insulation coating remains intact. It does not peel off, and its electrical properties are comparable to conventional organic enamel insulated wires. Therefore, it can be used in almost the same way as conventional organic enamel insulated wires for electrical equipment whose normal operating temperature is below the heat resistance temperature of overcoat resins and the like. On the other hand, when the temperature rises to a high temperature, the silicone resin etc. that make up the composite coating layer decomposes, its organic content disappears, and silica and composite oxides with silica are generated, and the decomposition products of this silica etc. It acts as a binder for the fine inorganic powder to form a strong ceramic layer. In this case, the ceramicization is carried out without temporary or rapid deterioration of electrical properties during decomposition, and the produced ceramic layer has extremely good electrical properties (insulating properties) at high temperatures. Therefore, even if the temperature rises to a high temperature, the electrical characteristics can be used continuously without deterioration. In particular, in the heat-resistant magnet wire of the present invention, since the overcoat resin layer is provided in a non-adherent state to the composite coating layer that turns into ceramic at high temperatures, the binder of the composite coating layer such as silicone resin is Even if the overcoat resin layer has not yet decomposed and disappeared during decomposition, the decomposed gas from the composite coating layer will be trapped between the composite coating layer and the overcoat resin layer, so the rapid temperature rise will cause the overcoat resin layer to decompose and disappear. Even if decomposition progresses rapidly, it is possible to prevent a situation in which the overcoat resin layer and composite coating layer are blown away and the conductor is exposed due to the generation of decomposition gas. Therefore, as the resin used for the overcoat resin layer, various resins can be used depending on the purpose of use, such as resins that have excellent heat resistance and are relatively difficult to decompose and disappear. In addition, in the process where the silicone resin as a binder decomposes due to rapid temperature rise due to overload due to equipment abnormality, the inorganic powder in the composite layer melts or half-melts, and the composite layer becomes fluid. When it has aged, the fluidized bed itself is scattered by the pressure of the decomposed gas of the inorganic polymer as the binder resin, and as a result, the ceramic layer is locally peeled off, and the conductor is locally exposed. However, in the case of the present invention, as mentioned above, inorganic powder that is half-melted or does not melt near the decomposition temperature of the silicone resin is used, so the decomposition process of the silicone resin due to rapid temperature rise The inorganic powder does not soften and become fluid, so the decomposition gas of the silicone resin is easily released from the gaps between the powder particles.
The composite layer is prevented from scattering.

That is, the ceramic layer does not peel off locally, and can sufficiently withstand subsequent use. In addition, if the inorganic powder melts or half-melts during a rapid temperature rise and the composite layer becomes soft and fluid, the composite layers of adjacent wires will stick together, and the wires may break due to rapid heating or cooling after turning into ceramic. This may cause the coating layer to peel off, but in the case of the present invention, as mentioned above, the decomposition temperature of the silicone resin as a binder (usually around 500°C)
Since an inorganic powder with a higher melting point is used, it is possible to prevent the wires from sticking together and sufficiently withstand rapid heating and cooling. Furthermore, when the silicone resin is decomposed, the inorganic powder does not become soft and fluid, and the inorganic powder is bonded to ceramic by silica, etc., which is a residual substance from the decomposition of the silicone resin. even if the particles are tightly bound)
As a result, it is difficult for distortion to accumulate due to rapid heating and cooling after being made into ceramic, and from this point of view, it can sufficiently withstand rapid heating and cooling. Three examples of this invention and a comparative example are described below.

Example 1 After immersing a nickel-plated copper wire with a diameter of 1.0 in a mixture consisting of 100 parts by weight of fine alumina powder with an average particle size of 5 μm, 35 parts by weight of methyl phenyl silicone resin, and 35 parts by weight of xylene, The silicone resin was cured in an oven heated to 400°C.

This operation was repeated to form a composite coating layer with a thickness of about 0.02 mm. Next, polyimide was continuously applied to this wire while applying tension with an elongation rate of about 1% and baked to form a resin layer with a thickness of about 20 μm, and the final wire was 1.0767 mm.
ft7! A heat-resistant magnet wire of Lφ was obtained. Example 2 After forming a composite coating layer in the same manner as in Example 1, polyimide was coated to a thickness of 12 μm, formal resin was further applied to a thickness of 8 μm and baked to a thickness of 1.076 mm.
A heat-resistant magnet wire of φ was obtained.

Example 3 Nickel plating with a diameter of 1.0 mm was placed in a mixture consisting of 50 parts by weight of alumina powder with an average particle size of 5 μm, 50 parts by weight of glass frit (softening temperature 900°C), 30 parts by weight of methylphenyl silicone resin, and 35 parts by weight of xylene. After the copper wire was immersed, the silicone resin was cured in a furnace at 350 to 400°C.

This operation was repeated to form a composite coating layer with a thickness of about 18 μm. Next, boron nitride (
BN) powder, then apply polyamide-imide to a thickness of 15 μm while applying about 2% tension to this wire.
Baking is performed to form an overcoat layer, and finally 1
．． A heat-resistant magnet wire with a diameter of 0.062 mm was obtained.

Example 4 11j! First, a thin layer of 3 μm silicone resin was applied to a 1φ nickel-plated copper wire, and then 20
A composite coating layer of Itm thickness was formed.

Next, a polyethylene film having a thickness of 10 μm was wrapped on top of this, and the films were fused together by heating to 200° C. to form an overcoat layer. In this way, a heat-resistant magnet wire was obtained. Example 5 A composite coating layer was formed in the same manner as in Example 3 on a nickel-plated copper wire of 1 muφ.

Next, the thickness on top of this: Gonigami 1! I::Erection:"{Shigeko=Touge:':!',

In this way, a heat-resistant magnet wire was obtained. Comparative Example The electric wire having the composite coating layer obtained in Example 1 was coated with urethane resin to a thickness of 15 μm, and the final outer diameter was 1.070.
m77! A heat-resistant magnet wire of φ was obtained.

The heat-resistant magnet wires of each of the above examples and comparative examples were tested for the state of the overcoat layer, flexibility, and heat resistance.

The results are shown in the table below. (The heat resistance properties due to rapid heating were evaluated after the overcoat resin had completely decomposed and disappeared by placing two twisted samples of the above electric wires in a furnace set at each temperature. From the results in the table As is clear, the overcoat resin layer configured in a non-adhesive state with respect to the composite coating layer has the flexibility to withstand self-diameter winding after 20% elongation, similar to conventional enameled wire. At the same time, it is possible to obtain the effect that the composite coating layer is unlikely to peel or fly even when the temperature rises rapidly.On the other hand, the composite coating layer is less likely to peel off or fly off even when the temperature rises rapidly.On the other hand, the composite coating layer that is bonded with the overcoat layer as in the comparative example is flexible. It can be seen that there are problems with the characteristics at high temperatures.As explained above, the heat-resistant magnet wire of the present invention has a composite coating layer formed on the conductor of a mixture of at least an inorganic fine powder and a silicone resin. Moreover, a flexible resin layer is formed on the composite coating layer in a non-adhesive state to the composite coating layer, and the composite coating layer is artificially baked under certain predetermined conditions. It is not made into a ceramic by heat treatment in advance, but is made into a ceramic only at high temperatures during use.

Therefore, the already proposed patent application 152647/1983
Like the heat-resistant magnet wire according to the invention of No. 1, there is no problem of deformation or oxidation of the winding base material such as the winding frame, and it is easy to process such as coil winding like ordinary organic enamel insulated wire. In addition, it can be used continuously for a long time like organic enamel insulated wire at normal operating temperatures below the heat resistance temperature of the resin. The coating layer is made of ceramic, which allows it to be used continuously from low to high temperatures without deteriorating its electrical properties, and after being made of ceramic, it can withstand repeated rapid heating and cooling. In addition, in the heat-resistant magnet wire of the present invention, the composite coating layer and the resin layer thereon are in a non-adhesive state, so compared to the heat-resistant insulated wire proposed above, the winding process is easier. This invention has particularly good processability as an overcoat resin, and can be used with various resins as there is no risk of part of the conductor being exposed due to decomposition gas when the composite coating layer is turned into ceramic. Therefore, it has the effect that better properties can be obtained by using the optimum resin depending on the purpose of use.

Claims (1)

[Claims] 1. A composite coating layer of a mixture consisting of 100 parts of inorganic fine powder with a particle size of 10 μm or less and 10 to 200 parts of silicone resin that does not melt or melt near the decomposition temperature of silicone resin and has excellent electrical properties is formed on the conductor. and a flexible resin layer is provided on the composite coating layer in a non-adhesive state to the composite coating layer, and a ceramic insulating layer is formed at high temperatures. net wire.