JPS6362042B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-resistant insulated wire used as a winding wire for various coil devices, and particularly to a heat-resistant insulated wire that is used after being subjected to winding processing such as coil winding in an unfired state and then fired at a high temperature. The present invention provides a heat-resistant insulated wire suitable for use in heat-resistant coils of devices that are subject to mechanical vibrations during use. Conventional heat-resistant insulated wires generally have a conductor coated with an inorganic insulator such as ceramic, but although these inorganic insulators have high heat resistance, they are usually hard and brittle, so they are used in motors, etc. When used in areas subject to rotation or vibration, the coating layer may be scraped or peeled off due to the wires rubbing against each other or against the winding frame, resulting in problems such as short circuits between the wires. A common method for solving this problem is to apply and impregnate the coil with an inorganic adhesive after the coil winding process to fix the coil winding. However, in this case, a liquid glass substance is usually used as the binder material for the inorganic adhesive for fixing the coil, which often causes problems with insulation properties at high temperatures, and when impregnating the coil from the outside. Since it is difficult to completely impregnate the inside of the coil with adhesive aggregate or binder material, there are drawbacks such as that it is difficult to completely prevent the wires from rubbing against each other on the inside of the coil. On the other hand, wires coated with a heat-resistant lubricant dispersed in a suitable liquid are wrapped around the insulating coating layer, and by lubricating between the windings, the coating layer is prevented from scraping or peeling. However, in this case, most of the lubricant material will be peeled off during the winding process.
Therefore, virtually no lubricant remains between the wires of the coil, making it difficult to obtain practical effects. On the other hand, recently, the inventors of the present invention, for example, filed a patent application
As proposed in No. 116239 (Japanese Unexamined Patent Publication No. 55-43746), a heat-resistant insulated wire in which a composite layer consisting of an inorganic powder such as alumina or silica and a binder resin such as an inorganic polymer such as silicone resin is formed on a conductor. In order to solve the above-mentioned problem, it is possible to mix an inorganic lubricant with other aggregate particles (inorganic powder) in the composite layer, but in this case, the amount of lubricant If the content is large, especially if it is in the form of scales, it becomes difficult to release the gas generated by the decomposition of the binder resin at high temperatures, and the coating layer is likely to fly off. If the amount is reduced, there is a problem that flexibility decreases and winding processability deteriorates. This invention has been made in view of the above circumstances, and further improves the heat-resistant insulated wire formed with a composite layer consisting of an inorganic polymer as a binder and an inorganic powder, which has already been proposed by the present inventor as described above. To provide a heat-resistant insulated wire that prevents peeling of the coating layer due to wires rubbing against each other even when used in a coil of a device subject to vibration, and that also prevents the aforementioned problems from occurring. The purpose is to In other words, the heat-resistant insulated wire of the present invention is produced by providing a lubricious coating layer made of an inorganic solid lubricating substance and a small amount of binder resin on the composite layer made of inorganic powder and inorganic polymer as described above. This solves the problems mentioned above. Hereinafter, the heat-resistant insulated wire of the present invention will be explained in more detail. FIG. 1 shows an example of the structure of a heat-resistant insulated wire according to the present invention, in which a composite layer 2 made of a mixture of an inorganic polymer and an inorganic powder is formed on a conductor 1, as will be described later. A lubricity coating layer 3 made of a mixture of an inorganic solid lubricity substance and a binder resin is formed on the composite layer 2, as will be described later. The conductor 1 may be a copper wire, a copper alloy wire, an aluminum wire, an aluminum alloy wire, a constantan wire, a silver wire, a gold wire, a platinum wire, a stainless steel wire, a nichrome wire, or a heat-resistant metal or alloy such as nickel or silver. A conductive metal wire such as a plated copper wire or a clad copper wire, preferably a heat-resistant conductive metal wire, is used. The inorganic polymer used as the binder material of the composite layer 2 imparts flexibility to the composite layer 2, and the product generated after decomposition during the calcination heat treatment after the winding process is an inorganic powder binder. It acts as a ceramic layer and produces a stronger ceramic layer. Such inorganic polymers include various silicone resins and modified silicone resins, such as siloxane and methyl methacrylate,
Copolymers with organic monomers such as acrylonitrile, or silicone resins and alkyd resins,
Copolymers with phenolic resin, epoxy resin, melamine resin, etc., as well as Si and Ti, B, Al, N,
Inorganic polymers with one or more elements such as P, Ge, As, Sb and oxygen in their skeletons, or Si and Ti, B,
Inorganic polymers with skeletons of one or more elements such as Al, N, P, Ge, As, Sb, oxygen, and carbon, as well as Ti, B, Al, N, P, Ge, As, Sb, etc. Inorganic polymers having oxygen and one or more of the above elements in their skeletons, or copolymers of these with the above organic monomers and resins, etc. can be used, but among these various inorganic polymers, Inorganic polymers of a type that have excellent flexibility and whose hydrocarbon groups etc. gradually decompose above the heat-resistant temperature, such as methyl-phenyl silicone, which have two or more types of groups with different decomposition temperatures. Therefore, it is most suitable that the proportion of inorganic substances decomposed and produced is as large as possible. Note that as a binder for the composite layer, an inorganic polymer such as the silicone resin described above may be used alone, but in particular, considering mechanical strength etc., other organic resin such as epoxy resin or polycarbonate may be used in addition to the inorganic polymer. , phenolic resin, etc. can be used in combination. In addition, the inorganic powder used in the composite layer 2 is preferably one that is half-melted or does not melt near the decomposition temperature of silicone resin used as a binder, that is, preferably has a melting point of 550°C or higher, more preferably 800°C or higher. It is desirable to use a material with excellent electrical insulation properties.
For example, crystalline powder, vitreous powder, or mixed powder thereof is used, more specifically alumina (Al ₂ O ₃ ), barium titanate (BaTiO ₃ ), calcium titanate (CaTiO ₃ ), lead titanate. (PbTiO ₃ ), zircon (ZrSiO ₄ ), barium zirconate (BaZrO ₃ ), steatite (MgSiO ₃ ),
Silica (SiO ₂ ), beryllia (BeO), zirconia (ZrO ₂ ), magnesia (MgO), clay, montmorillonite, bentonite, kaolin, or ordinary high melting point glass frits, oxides such as mica, boron nitride (BN), Nitrides such as silicon nitride, mixed powders thereof, etc. are used. The particle size of these inorganic powders is appropriate depending on the diameter of the conductor, but usually
Preferably, the diameter is 10 μm or less. Further, the particle size of the inorganic powder may be uniform, but it is desirable that large-diameter particles and small-diameter particles are well combined so that the composite layer has a structure as dense as possible. It should be noted that if the mixture used in each layer of the composite layer 2 contains too little binder material whose main component is an inorganic polymer, the flexibility of the composite layer 2 will be insufficient and coil winding will be difficult; If there is too much of the binder material, which is mainly composed of polymers, it will become soft and mechanically weak at high temperatures during use, and the amount of gas generated during high-temperature decomposition will increase, leading to the risk of flaking and peeling of the composite layer. For these reasons, the blending ratio of the mixture in composite layer 2 is 10 to 200 parts by weight of inorganic polymer to 100 parts by weight of inorganic powder;
Preferably it is 20 to 60 parts by weight. Note that the thickness of the composite layer 2 is preferably about 1 to 100 μm. Inorganic solid lubricant materials used in the mixture of the lubricant coating layer 3 formed on the composite layer 2 as described above include boron nitride (BN), molybdenum disulfide (MoS ₂ ), and tungsten disulfide. (WS ₂ ), graphite fluoride ((CF) _o ), mica, etc.
Among these, BN is the most suitable because of its excellent heat resistance and insulation properties. Moreover, the particle size of this solid lubricating substance is preferably about 1 μm to 5 μm. On the other hand, it is desirable that the binder resin used for the lubricious coating layer 3 is one that does not adversely affect the composite layer 2 in terms of flexibility during the wrapping process. For example, a resin with a glass transition temperature of 35 to 50°C and a melting point of 80 to 100°C is preferable, and in order to prevent the composite layer 2 from flying off during high-temperature firing, the binder resin used for the composite layer 2 should be used. It is desirable to use an organic resin that decomposes at a temperature higher than or lower than that, or an inorganic polymer resin whose organic groups decompose. Furthermore, in order to minimize gas generation from the lubricating coating layer 3 during high-temperature firing, it is desirable to select a binder resin that can provide the desired adhesive strength with as small a blending ratio as possible. Taking these points into consideration, the binder resin for the lubricity coating layer 3 is selected from organic resins such as polyethylene oxide, methacrylic ester resin, acrylic ester resin, polyurethane, or cellulose such as hydroxyethyl cellulose and methyl cellulose. It is preferable to use polyvinyl alcohol and the like, and as the inorganic polymer, a relatively low polymer of silicone resin is preferable. Note that the lubricity coating layer 3
The blending ratio of the binder resin and the inorganic solid lubricating substance constituting is 0.1 to 50 parts by weight of the binder resin to 100 parts by weight of the solid lubricating substance. If the binder resin is less than 0.1 part by weight, the adhesive strength may be insufficient and the lubricating coating layer 3 may peel off during the wrapping process, and if it exceeds 50 parts by weight, a large amount of gas will be generated due to decomposition of the resin during firing. There is a risk that the composite layer 2 may also fly off. In other words, solid lubricating substances are mainly composed of scale-like particles with a layered lattice, but such scale-like particles tend to prevent the release of decomposed gas from the binder resin during firing, and therefore a large amount of decomposition occurs during firing. If gas is generated, scattering and peeling will easily occur, but by limiting the amount of binder resin blended to a small amount of 50 parts by weight or less, the amount of decomposed gas generated during firing can be reduced.
It prevents flying and peeling and can be used without any problems even after firing. The thickness of the lubricious coating layer 3 is 1 μm.
The thickness is preferably about 20 μm. The composite layer 2 can be formed by forming a slurry composition of an inorganic polymer and an inorganic powder in an appropriate solvent, and applying the slurry composition onto a conductor and curing or semi-curing it, or by applying a mixture of an inorganic polymer and an inorganic powder to a slurry composition and applying the slurry composition onto the conductor. It may be formed by any appropriate means such as extrusion coating on the conductor. On the other hand, in order to form the lubricious coating layer 3, an appropriate dispersion medium or thickener is added as necessary to the binder resin solution dissolved using water, an organic solvent, etc. as a dispersion medium. A method can be adopted in which a lubricant such as BN is dispersed, the resulting slurry is applied onto the composite layer, and the dispersion medium is volatilized or the binder resin is cured or semi-cured. In some cases, the above-mentioned lubricious coating layer may be formed by wrapping or vertically covering the composite layer with a tape-like material such as mica adhered to a suitable base material using a binder resin. It may be formed. However, in the latter case, it is necessary to cover the composite layer so as not to prevent gas release from the composite layer during high-temperature firing. The heat-resistant wire having the composite layer 2 and the lubricating coating layer 3 formed on the conductor 1 as described above is coil-wound onto a winding frame 4 such as a bobbin as shown in FIG. 2 in an unfired state. The composite layer 2 is highly flexible in its unfired state, and therefore there is little risk of cracks occurring in the composite layer 2 during winding. Furthermore, since the solid lubricant material such as BN, which is the main component of the lubricant coating layer 3, is bound by the binder resin, it is prevented from peeling off during the winding process. After wrapping as described above, 400 ~
The composite layer 2 is fired by heating to about 700°C. By this firing heat treatment, the inorganic polymer in the composite layer 2 is decomposed, and the decomposition products act as a binder for the inorganic powder, so that the composite layer 2 becomes a strongly bonded ceramic layer. At the same time, the binder resin of the lubricant coating layer 3 decomposes and disappears, causing the lubricant coating layer 3 to collapse or semi-collapse, and as shown in FIG. I will fill it up. Therefore, even when vibrations are applied, the wires, that is, the composite layers of adjacent wires, do not rub against each other, and since there are appropriate gaps between the solid lubricant powder filling the spaces between the wires, vibrations are prevented. Therefore, problems such as short circuits are less likely to occur even with strong mechanical vibrations. In the above explanation, it was assumed that a composite layer was formed directly on the conductor and a lubricating coating layer was formed directly on the composite layer, but in some cases, as shown in FIG. It is also possible to form a thin layer 5 of about 1 to 5 μm made of an inorganic polymer similar to the inorganic polymer used in the composite layer, and then form the composite layer 2 and the lubricating coating layer 3 in that order. good. If the thin layer 5 of inorganic polymer is interposed between the conductor 1 and the composite layer 2 in this way, the bonding force between the composite layer and the conductor is increased, so that it can be used during the wrapping process when unfired or after firing. It is possible to effectively prevent the conductor from peeling off due to vibration or the like. Further, as shown in FIG. 4B, between the composite layer 2 formed on the conductor 1 and the lubricating coating layer 3, 1 to A thin layer 6 of about 5 μm may be interposed, which increases the bonding force of the lubricant coating layer 3 to the composite layer 2 and effectively prevents the lubricant coating layer 3 from peeling off during the winding process. can. Furthermore, as shown in FIG. 4C, inorganic polymer thin layers 5 and 6 may be interposed between the conductor 1 and the composite layer 2 and between the composite layer 2 and the lubricating coating layer 3, respectively. . Examples and comparative examples of this invention are described below. Example 1 A composition consisting of 32 parts by weight of silicone varnish (resin content), 68 parts by weight of alumina powder particles with an average particle size of 1.5 μm or less, and a solvent was applied onto a silver wire with an outer diameter of 0.4 mm, and heated at 350 to 450°C. It was cured at temperature to form a 24 μm thick composite layer. Next, a slurry consisting of 1 part by weight of polyethylene oxide, 99 parts by weight of BN powder, and a solvent was applied onto the composite layer and dried to form a lubricious coating layer with a thickness of 7 μm to obtain a heat-resistant insulated wire. Example 2 A composition similar to that used in Example 1 was applied onto a nickel wire with an outer diameter of 0.30 mm and cured.
A composite layer with a thickness of 23 μm was formed. Next, 5 parts by weight of silicone varnish (resin content) and BN
A slurry consisting of 95 parts by weight of powder and a solvent was applied and dried, and then BN powder was applied and heat treated to an extent that it hardly hardened, thereby obtaining a heat-resistant insulation having a lubricious coating layer approximately 6 μm thick. Comparative Example 1 A composition similar to that used in Example 1 was applied onto a nickel-plated wire having an outer diameter of 0.30 mm to obtain a heat-resistant insulated wire in which only a composite layer with a thickness of 23 μm was formed. 50 pieces of heat-resistant insulated wire of each of the above examples and comparative examples.
After winding 7 layers around a mmφ bobbin and firing at a temperature of 400 to 700°C to form the composite layer into ceramic, each coil was subjected to a vibration test at 4G according to the JISD1601 (77) method. The results are shown in Table 1 below. In addition, in Table 1, ○ mark indicates "no abnormality",
An x mark indicates "a short circuit occurred between lines."

[Table] As is clear from Table 1, all the coils that were wound and fired using the heat-resistant insulated wires of the examples of the present invention had good vibration resistance characteristics. In particular, Example 1 uses a silver conductor with poor adhesion, but it has become clear that it can be used without any problems in this case as well. As is clear from the above description, even when the heat-resistant insulated wire of the present invention is subjected to strong vibrations and accelerations when used in various coil devices, the composite layer that is the insulation coating of the wire peels off due to the wires rubbing against each other. Various effects can be obtained, such as effectively preventing the winding from occurring and not impairing the winding workability of the wire itself.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the structure of the heat-resistant insulated wire of the present invention, FIG. 2 is a schematic cross-sectional view showing the same wire wound into a coil, and FIG. FIGS. 4A, 4B, and 4C are schematic cross-sectional views showing other structural examples of the heat-resistant insulated wire of the present invention, respectively. DESCRIPTION OF SYMBOLS 1...Conductor, 2...Composite layer, 3...Lubricating coating layer.

Claims (1)

[Claims] 1 100 parts by weight of inorganic powder and inorganic polymer on conductor
A composite layer consisting of 10 to 200 parts by weight is formed, and an inorganic solid lubricant material is further formed on the composite layer.
A heat-resistant insulated wire characterized in that a lubricating coating layer is formed comprising 100 parts by weight of a binder resin and 0.1 to 50 parts by weight of a binder resin.