JP2005203334A - Insulated wire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating wire in which thick-filming of an enamel layer can be realized without reducing adhesion strength of the conductor of the insulating wire and the enamel layer. <P>SOLUTION: This is the insulating wire which comprises at least one layer of enamel-baked layer on the outer periphery of a conductor and at least one layer of extrusion coating resin layer on the outside of it and the total of the thickness of the enamel-baked layer and the extrusion coating resin layer is 60 μm or more. Then, in this insulating wire, the thickness of enamel-baked layer is made 50 μm or less. Furthermore, in this insulating wire, the extrusion coating resin layer is made of a resin material which has a tensile modulus of elasticity of 1,000 MPa or more at 25°C and a tensile modulus of elasticity of 10 MPa or more at 250°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an insulated wire, and more particularly to an inverter surge resistant insulated wire.

  Inverters have come to be attached to many electrical devices as efficient variable speed control devices. The inverter is switched at several kHz to several tens of kHz, and a surge voltage is generated for each pulse. Inverter surge is a phenomenon in which reflection occurs at a discontinuous point of impedance in the propagation system, for example, at the start and end of a connected wiring, and as a result, a voltage twice as large as the inverter output voltage is applied. In particular, an output pulse generated by a high-speed switching element such as an IGBT has a high voltage agility, so that even if the connection cable is short, the surge voltage is high, and furthermore, the voltage attenuation by the connection cable is also small. A voltage nearly doubled is generated.

  Insulator-related equipment, for example, electrical equipment coils such as high-speed switching elements, inverter motors, transformers, etc., insulated wires, mainly enameled wires, are used as magnet wires. Moreover, as described above, in inverter-related equipment, a voltage nearly twice as high as the inverter output voltage is applied, so that it is possible to minimize inverter surge deterioration of enameled wire, which is one of the materials constituting these electrical equipment coils. It is becoming required.

  In general, partial discharge deterioration includes degradation of molecular chains caused by collision of charged particles generated by the partial discharge of an electrically insulating material, sputtering deterioration, thermal melting or thermal decomposition deterioration due to local temperature rise, chemical deterioration due to ozone generated by discharge, etc. Is a complicated phenomenon. For this reason, it can be seen that the thickness of the electrically insulating material deteriorated by the actual partial discharge is reduced.

  It is considered that the inverter surge degradation of the insulated wire proceeds by the same mechanism as general partial discharge degradation. In other words, the inverter surge degradation of enameled wire is a phenomenon in which partial discharge occurs in the insulated wire due to high surge voltage generated by the inverter, and the coating of the insulated wire causes partial discharge degradation due to the partial discharge, that is, high frequency partial discharge. It is deterioration.

  In recent electric equipment, an insulated wire capable of withstanding a surge voltage of 500 V has been demanded. That is, the partial discharge generation voltage needs to be 500 V or more. Here, the partial discharge generation voltage is a value measured by a device called a commercially available partial discharge tester. The measurement temperature, the frequency of the AC voltage used, the measurement sensitivity, etc. are changed as necessary. The above values are measured at 25 ° C., 50 Hz, 10 pC, and the effective value of the voltage at which partial discharge occurs. It is.

  When measuring the partial discharge generation voltage, the most severe situation when used as a magnet wire is assumed, and a method for producing a sample shape that can be observed between two insulating wires in close contact is used. For example, with respect to an insulating wire having a circular cross section, two insulating wires are spirally twisted to make line contact, and a voltage is applied between the two. In addition, with respect to an insulating wire having a square cross-sectional shape, the long surfaces of two insulating wires are brought into surface contact with each other, and a voltage is applied between the two.

  To prevent degradation of the enamel layer of the insulated wire due to such partial discharge, in order to obtain an insulated wire that does not generate partial discharge, that is, high partial discharge generation voltage, a resin having a low relative dielectric constant is used for the enamel layer. Or a method of increasing the thickness of the enamel layer. However, most commonly used resin varnish resins have a relative dielectric constant between 3 and 4, and there is no specific dielectric constant that is low, and other enamel layers are required. In consideration of characteristics (heat resistance, solvent resistance, flexibility, etc.), it is practical that it is not always possible to select a material having a low relative dielectric constant. Therefore, in order to obtain a high partial discharge generation voltage, it is essential to increase the thickness of the enamel layer. When these resins having a relative dielectric constant of 3 to 4 are used for the enamel layer, the thickness of the enamel layer is required to be 60 μm or more from experience in order to set the partial discharge generation voltage to 500 V or more as a target.

However, in order to increase the thickness of the enamel layer, the number of times of passing through a baking furnace in the manufacturing process is increased, and the thickness of the coating made of copper oxide on the copper surface, which is the conductor, grows. The adhesive strength of the is reduced. In particular, when an enamel layer having a thickness of 50 μm or more is obtained, the number of passes through the baking furnace exceeds 10 times. It has been found that the adhesive strength between the conductor and the enamel layer is extremely reduced when the number of times exceeds 10 times.
In addition, there is a method to increase the thickness that can be applied by one baking so as not to increase the number of times of passing through the baking furnace, but in this method, the solvent of the varnish cannot be completely evaporated and bubbles are formed in the enamel layer. There was a drawback of remaining.
Attempts have been made so far to provide added value on characteristics (characteristics other than partial discharge voltage) by providing a coating resin outside the enameled wire. As conventional techniques in the configuration in which the extrusion coating layer is provided on the enamel layer, there are Patent Documents 1 to 3 and the like. From the viewpoint of making the partial discharge generation voltage and the adhesion between the conductor and the enamel layer compatible, The thickness configuration of the extrusion coating was not satisfactory.

Further, in recent electrical equipment, various performances such as heat resistance, mechanical characteristics, chemical characteristics, electrical characteristics, reliability, and the like have been required to be further enhanced from conventional ones. Among them, insulation wires such as enameled wires used as magnet wires for space electrical equipment, aircraft electrical equipment, nuclear electrical equipment, energy electrical equipment, and automotive electrical equipment have excellent wear resistance. However, heat aging characteristics and solvent resistance have been demanded.
In recent years, electrical devices such as motors and transformers have been increasingly miniaturized and improved in performance, and many uses such as pushing insulated wires into very narrow parts can be seen. Became. Specifically, it is no exaggeration to say that the performance of a rotating machine such as a motor is determined depending on how many wires can be put in the stator slot. As a result, the ratio of the cross-sectional area of the conductor to the cross-sectional area of the stator slot (space factor) has become very high in recent years.
When the electric wire having a round cross-section is densely filled in the stator slot, the gap that becomes a dead space and the cross-sectional area of the insulating film become a problem. For this reason, the user tries to improve the space factor as much as possible by pushing the electric wire into the stator slot as the electric wire having a round cross section is deformed. However, reducing the cross-sectional area of the insulating film has not been performed because it sacrifices its electrical performance (such as dielectric breakdown).
For the above reasons, as a means for improving the space factor, recently, attempts have been made to use a rectangular wire whose conductor shape is similar to a square shape (square or rectangle). The use of a flat wire has a dramatic effect on improving the space factor, but it is difficult to uniformly apply an insulating film on a flat conductor, and the thickness of the insulating film is particularly difficult for insulated wires with a small cross-sectional area. It is not so popular because it is difficult to control.
As a characteristic of the insulating film necessary for coiling a motor or a transformer, there is a processing performance of the film. This is because, in the coil processing step described above, if the wire coating is damaged, the electrical insulation performance is lowered.
Various methods are conceivable as a method for imparting this processing resistance to the wire coating. This can be achieved by applying lubricity to the film to reduce the coefficient of friction and reducing the damage caused by coil processing, or by improving the adhesion between the film and the electrical conductor to prevent the film from peeling off the conductor. For example, the insulation performance can be maintained.
The former method of imparting lubrication performance is to apply a lubricant such as wax to the surface of the wire, or to add a lubricant to the insulation film and bleed out the lubricant to the surface of the wire when manufacturing the wire. A method of imparting lubrication performance has been adopted in the past, and there are many examples. However, since this method of imparting lubrication performance does not improve the strength of the electric wire film itself, it seems to be effective against the cause of trauma, but the effect is actually limited.
As a means conventionally used, as for the method of reducing the friction coefficient of the surface of the insulating film as described above, in Patent Document 4, wax, oil, surfactant, solid lubricant, etc. In Patent Document 5, etc., it is possible to apply and bake a lubricant that is emulsified in water and a resin that can be emulsified in water and solidified by heating. For example, it has been proposed to lubricate the insulating coating itself by adding fine polyethylene powder. The above method is considered to improve the surface lubricity of the insulated wire, and as a result, to protect the insulating layer from damage by the surface slippage of the wire.
However, since these fine powders are added in a complicated manner and are difficult to disperse, many of these fine powders dispersed in a solvent are added to the insulating paint. It has been.
Although these self-lubricating components are improved in self-lubricating performance (coefficient of friction) due to the lubricating components, characteristics such as reciprocating wear due to workability are not observed. In addition, many self-lubricating components such as polyethylene and polytetrafluoroethylene are separated in the insulating paint due to the difference in specific gravity from the insulating paint, and great care must be taken when using these paints.
JP 59-040409 A Patent No. 1998680 (Japanese Patent Publication No. 7-031944) JP 63-195913 JP JP-A-61-269808 JP-A-62-200605 JP 63-29412 A

  An object of this invention is to provide the insulated wire with a high partial discharge generation voltage. Another object of the present invention is to provide an insulating wire that can realize the thickening of the insulating layer for increasing the partial discharge generation voltage without lowering the adhesive strength between the conductor of the insulating wire and the enamel layer. Another object of the present invention is to provide an insulating wire that satisfies the requirements for wear resistance, heat aging characteristics, and solvent resistance required for an insulating wire. Another object of the present invention is to provide an insulated wire capable of increasing the space factor without lowering the partial discharge generation voltage. Another object of the present invention is to provide an insulated wire having good insertability when processing a motor or the like. Still another object of the present invention is to provide an insulating wire and a method for manufacturing the same, which prevent a partial discharge generation voltage from being lowered at that portion even when bending to a small radius.

  As a result of intensive studies to solve the problems of the above-described conventional techniques, the present inventors have found that the partial discharge generation voltage can be increased by providing an extrusion-coated resin layer outside the enamel layer of the enameled wire. . The present invention has been made based on this finding.

That is, the present invention
(1) At least one enamel baking layer on the outer periphery of the conductor and at least one extrusion coating resin layer on the outer side thereof, and the total thickness of the enamel baking layer and the extrusion coating resin layer is 60 μm or more. Insulated wire, characterized in that
(2) The insulated wire according to (1), wherein the thickness of the enamel baking layer is 50 μm or less,
(3) The extrusion-coated resin layer is made of a resin material having a tensile elastic modulus at 25 ° C. of 1000 MPa or more and a tensile elastic modulus at 250 ° C. of 10 MPa or more (1) or (2) Insulated wire according to item
(4) An insulated wire having at least one enamel-baked layer on the outer periphery of a conductor having a rectangular cross section and at least one extrusion-coated resin layer on the outer side thereof, and a pair of opposing 2 in the cross section Any one of (1) to (3), wherein the thickness of the extrusion-coated resin layer provided on the side is different from the thickness of the extrusion-coated resin layer provided on the other pair of opposing two sides. Insulated wire according to item
(5) An adhesive layer is provided between the enamel baked layer and the extrusion-coated resin layer, and the adhesive force between the enamel baked layer and the extrusion-coated resin layer is reinforced using the adhesive layer as a medium. The insulated wire according to any one of (1) to (4), and
(6) On the outer periphery of the enamel baking layer, a varnished resin is baked to form an adhesive layer, which is then contacted with an extrusion coating resin that is in a molten state at a temperature higher than the glass transition temperature of the resin. The method for producing an insulated wire according to item (5), wherein the layer and the extrusion-coated resin layer are heat-sealed.

The insulated wire of the present invention satisfies both the “partial discharge generation voltage” and the “conductor / enamel layer adhesive strength”, and the inverter surge deterioration is less likely to occur.
Further, when the thickness of the enamel layer is 50 μm or less, the number of times of passing through the baking furnace can be reduced, and the adhesive force between the conductor and the enamel layer can be prevented from being extremely reduced.
Further, when the extrusion-coated resin layer is made of a resin material having a tensile elastic modulus at 25 ° C. of 1000 MPa or more and a tensile elastic modulus at 250 ° C. of 10 MPa or more, wear resistance, heat aging characteristics, solvent resistance It is also excellent in properties.
Further, in the case of a conductor insulated wire having a rectangular cross section, if the thickness of the extrusion-coated resin layer of the pair of surfaces where discharge occurs is a predetermined thickness, the thickness of the other pair of facing surfaces Even if it is thinner than that, the partial discharge generation voltage can be maintained, and the space factor can be further increased.
In addition, the insulated wire of the present invention has a small coefficient of static friction and good insertability during electric wire motor processing.
Moreover, generation | occurrence | production of the above wrinkles can be prevented by introduce | transducing the layer which has an adhesive function between an enamel layer and an extrusion coating resin layer, and improving adhesive strength.
Further, an varnished resin is baked on the outer periphery of the enamel baking layer to form an adhesive layer, and then an extruded coating resin in a molten state at a temperature higher than the glass transition temperature of the resin used in the adhesive layer; The insulated wire of the present invention can be suitably produced by bringing the enamel baked layer and the extrusion-coated resin layer into thermal contact with each other.

One embodiment of the present invention has at least one enamel baked layer on the outer periphery of the conductor and at least one extruded coated resin layer on the outside thereof, and the thickness of the enamel baked layer and the extruded coated resin layer is Insulated wires with a total of 60 μm or more. The thickness of the enamel baking layer is preferably 50 μm or less. The insulated wire of the present invention is suitable for heat-resistant windings, for example, inverter-related equipment, high-speed switching elements, inverter motors, transformers and other electrical equipment coils, space electrical equipment, aircraft electrical equipment, nuclear power It can be used for an electrical device, an electrical device for energy, a magnet wire for an automotive electrical device, and the like.
There are two types of partial discharge that occur in a stator slot of a motor or the like, when it occurs between the slot and the wire, and when it occurs between the wire and the wire. Therefore, by using an insulating wire in which the thickness of the extrusion-coated resin layer provided on the flat surface is different from the thickness of the extrusion-coated resin layer provided on the edge surface, while maintaining the value of the partial discharge generation voltage, the motor It is possible to improve the ratio (space factor) of the total cross-sectional area of the conductor to the total cross-sectional area in the slot.
When arranging wires with different thicknesses on the edge surface and flat surface in a single row in the slot, if a discharge occurs between the slot and the wire, arrange so that the thick film surface is in contact with the slot, and between adjacent wires The film thicknesses are arranged in the thinner one. More lines can be inserted than the thin film thickness, and the space factor is improved. At this time, the value of the partial discharge generation voltage can be maintained. Similarly, if electric discharge is likely to occur between wires, the thicker side should be the surface in contact with the wire, and the side facing the slot should be thinner. Will improve. At this time, the value of the partial discharge generation voltage can be maintained.
The flat surface mentioned here refers to a pair of long sides out of two opposing sides of a pair of rectangular wires having a rectangular cross section. Further, the edge surface refers to a pair of short sides of two sides facing each other.
Further, when the thickness of the extrusion-coated resin layer is different between a pair of opposing two sides of the cross section and another pair of opposing two sides, another one when the thickness of the pair of opposing two sides is 1. The thickness of the two opposite sides of the pair is in the range of 1.01-5. Preferably it is the range of 1.01-3.

(conductor)
As the conductor used in the present invention, those conventionally used for insulated wires can be used. Preferably, the oxygen content is low oxygen copper of 30 ppm or less, more preferably 20 ppm or less. Or an oxygen-free copper conductor. When the oxygen content is 30 ppm or less, when the conductor is melted with heat to prevent welding, voids due to oxygen contained in the welded portion are not generated, and the electrical resistance of the welded portion is prevented from deteriorating. The strength of the welded portion can be maintained.
Further, the conductor having a desired cross-sectional shape can be used, but a conductor having a shape other than a circle is preferably used, and a rectangular shape is particularly preferable. Furthermore, it is desirable to have a shape with chamfers (radius r) at the four corners in terms of suppressing partial discharge from the corners.

(Enamel layer)
The enamel baking layer (hereinafter also simply referred to as “enamel layer”) is formed by applying and baking a resin varnish on a conductor a plurality of times. The method of applying the resin varnish may be a conventional method. For example, a method of using a varnish application die having a similar conductor shape, or a “universal die formed in a cross-beam shape if the conductor cross-sectional shape is a quadrangle” Can be used. The conductors coated with these resin varnishes are baked in a baking furnace in the usual manner. Although the specific baking conditions depend on the shape of the furnace used, etc., in the case of a natural convection type vertical furnace of about 5 m, the passage time is set to 10 to 90 seconds at 400 to 500 ° C. Can be achieved.

As the enamel resin for forming the enamel layer, those conventionally used can be used, for example, polyimide, polyamideimide, polyesterimide, polyetherimide, polyimide hydantoin-modified polyester, polyamide, formal, polyurethane, polyester, Polyvinyl formal, epoxy, and polyhydantoin are mentioned, and polyimide resins such as polyimide, polyamideimide, polyesterimide, polyetherimide, and polyimide hydantoin-modified polyester that are excellent in heat resistance are preferable.
Moreover, these may be used individually by 1 type, and may mix and use 2 or more types.

The thickness of the enamel layer is preferably 50 μm or less, and more preferably 40 μm or less, in order to reduce the number of passes through the baking furnace and prevent the adhesive force between the conductor and the enamel layer from being extremely reduced. Moreover, in order not to impair the withstand voltage characteristics and the heat resistance characteristics, which are characteristics necessary for an enameled wire as an insulating wire, it is preferable that the enamel layer has a certain thickness. The lower limit thickness of the enamel layer is not particularly limited as long as it does not cause pinholes, and is preferably 3 μm or more, more preferably 6 μm or more.
The enamel layer may be a single layer or a plurality of layers.

(Extruded resin layer)
In the present invention, in order to obtain an insulated wire having a high partial discharge generation voltage, at least one extrusion-coated resin layer is provided outside the enamel baking layer. The advantage of the extrusion coating method is that the thickness of the insulating layer can be increased without increasing the thickness of the oxide film layer of the conductor because it is not necessary to pass through a baking furnace in the manufacturing process.

  The resin used for the extrusion-coated resin layer may be anything as long as it can be extruded. However, in order to reduce the partial discharge generation voltage, those having a relative dielectric constant of 4.5 or less are preferable. For example, polypropylene (PP), polymethylpentene (PMP), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoro Ethylene / perfluoroalkyl vinyl ether copolymer (PFA), polyamide (PA), polyester (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene ether (PPE), polyether ether ketone (PEEK), Aromatic polyester, polyimide (PI), alicyclic olefin, polyetherimide (PEI), polyamideimide (PAI), polyethersulfone (PES), polyphenylene sulfide PPS), polymethylpentene (PMP), syndiotactic polystyrene (SPS), polyketone (PK), polysulfone (PSU), polyphenyl sulfone (PPSU), polyacetal (POM) and the like Ageraru. More preferably, the dielectric constant is 4.0 or less.

  Here, the relative dielectric constant can be measured with a commercially available dielectric constant measuring apparatus. The measurement temperature and frequency are changed as necessary. In the present invention, unless otherwise specified, it means values measured at 25 ° C. and 50 Hz.

  And in order to satisfy | fill the request | requirement that a partial discharge generation voltage is 500 V or more, the sum total of the thickness of an enamel layer and an extrusion coating resin layer needs 60 micrometers or more. That is, it is preferable that the enamel layer thickness is 50 μm or less and the total thickness is 60 μm or more because both “partial discharge generation voltage” and “conductor / enamel layer adhesive strength” can be satisfied.

  In the present invention, the adhesive strength between the conductor and the enamel layer is, for example, 8. JIS C 3003 enamel wire test method. Adhesiveness, 8.1b) It can be performed in the same manner as the torsion method, and can be evaluated by the number of rotations until the coating floats. The same can be done for a rectangular wire having a square cross section. In this case, the one having a rotation speed of 15 rotations or more until the coating is lifted is assumed to have good adhesion.

  Moreover, in one preferable aspect of this invention, an extrusion coating resin layer consists of a resin material whose tensile elasticity modulus in 25 degreeC is 1000 Mpa or more, and whose tensile elasticity modulus in 250 degreeC is 10 Mpa or more. The tensile modulus at 25 ° C is more preferably 2000 MPa or more. The tensile modulus at 250 ° C. is more preferably 100 MPa or more.

  The insulated wire of the present invention can also cope with wear resistance, heat aging characteristics, and solvent resistance, which are required for insulated wires. Abrasion resistance is an index of the degree of scratches when an insulated wire is processed into a motor or the like, and a static friction coefficient is a degree of ease of insertion. The heat aging characteristic is an index for maintaining reliability for a long time even when used in a high temperature environment. Solvent resistance is also required due to diversification of usage environment and assembly process.

  In the present invention, the abrasion resistance is evaluated by, for example, 9. JIS C 3003 enamel wire test method. This can be done in the same way as wear resistance (round wire). In the case of a rectangular wire with a square cross section, the process is performed for the four corners. It can be evaluated as being very excellent at 2000 g or more.

  In the present invention, the evaluation of the heat aging property is performed, for example, according to JIS C 3003 enamel wire test method. What was wound according to flexibility can be carried out by visually checking whether there is a crack in the enamel layer or the extrusion-coated resin layer after leaving it in a high-temperature bath at 180 ° C. for 300 hours (h). In this case, if there is no abnormality, it can be evaluated as very excellent.

  In the present invention, the solvent resistance is evaluated by, for example, JIS C 3003 enameled wire test method. What was wound according to flexibility can be carried out by visually observing the surface of the enamel layer or the extrusion-coated resin layer after being immersed in a solvent for 10 seconds. In this case, three types of solvents are used: acetone, xylene, and styrene, and the temperature is set at two levels: normal temperature and 150 ° C. (the sample is immersed in a solvent in a hot state after being heated at 150 ° C. for 30 minutes). Without it, it can be evaluated as very excellent.

  As a result of numerous experiments, the present inventors have found a certain correlation between wear resistance, heat aging characteristics, solvent resistance, and tensile modulus. That is, if the tensile elastic modulus at 25 ° C. is 1000 MPa or more, the wear resistance performed at room temperature can achieve 2000 g or more (mass). Further, if the tensile elastic modulus at 250 ° C. is 10 MPa or more, the heat aging characteristic performed at 180 ° C. can achieve 300 h. Further, it was also derived that if the resin satisfies the above two items, the solvent resistance, which is a necessary characteristic remaining, can achieve good results at room temperature and 150 ° C.

  Here, the tensile modulus is a value measured with a commercially available viscoelasticity measuring device, and the control mode, frequency, strain amount, measurement temperature, and the like at the time of measurement can be changed as necessary. In the present invention, unless otherwise specified, the tensile temperature, the frequency is 1 Hz, the strain amount is 1/1000, and the measurement temperature means a value measured while changing at a heating rate of 5 ° C./min.

  The resin material having a tensile elastic modulus at 25 ° C. of 1000 MPa or more and a tensile elastic modulus at 250 ° C. of 10 MPa or more is not particularly limited. For example, polyphenylsulfone (PPSU), polyamideimide ( PAI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK) and the like, and PPS and PEEK are more preferable. Further, these resins may be blended with other resins, elastomers, or the like as long as the tensile elastic modulus does not deviate from the above range. Furthermore, a block copolymer with another monomer can be used as long as the tensile elastic modulus does not deviate from the above range.

In another preferred embodiment of the present invention, an adhesive layer is provided between the enamel baked layer and the extrusion-coated resin layer, and the adhesive force between the enamel baked layer and the extrusion-coated resin layer is reinforced using the adhesive layer as a medium. Insulated wire.
Further, another preferred embodiment of the present invention is that the varnished resin is baked on the outer periphery of the enamel baked layer to form an adhesive layer, and the glass transition temperature of the resin used for the adhesive layer in the subsequent extrusion coating step. It is the manufacturing method of the insulated wire which heat-fuses an enamel layer and an extrusion coating resin layer by making it contact with the extrusion coating resin which is a molten state of higher temperature.

When the adhesive force between the extrusion coating resin layer and the enamel baking layer is not sufficient, when severe processing conditions such as bending to a small radius, wrinkles of the extrusion coating resin layer occur inside the bending arc There is. When such wrinkles occur, a space is generated between the enamel layer and the extrusion-coated resin layer, which may lead to a phenomenon that the partial discharge generation voltage decreases.
In order to prevent this decrease in the partial discharge generation voltage, it is necessary to prevent wrinkles from occurring inside the arc of bending, and a layer having an adhesive function is introduced between the enamel layer and the extrusion coating resin layer. By increasing the adhesive strength, the generation of wrinkles as described above can be prevented.

  The measurement device and measurement conditions for the partial discharge generation voltage at the bent part of the insulated wire are the same as those measured by the partial discharge tester described above, but assuming the most severe conditions, the sample shape is divided into two pieces of insulation. The measurement is performed by applying a voltage between the wire conductor and the metal foil using a wire in which a bent portion of one insulated wire is covered with a metal foil (aluminum or the like) instead of closely contacting the wire. The measurement value obtained by this measurement method is different from that in the case where voltage is applied to the two insulated wires that are brought into close contact with each other.

  Any resin can be used for the adhesive layer as long as it can be heat-sealed. However, since the resin needs to be varnished, it is preferably an amorphous resin that is easily dissolved in a solvent. Furthermore, in order not to reduce the heat resistance as the insulating wire, a resin having excellent heat resistance is preferable. Considering these matters, preferred resins include polysulfone (PSU), polyethersulfone (PES), polyetherimide (PEI), polyphenylsulfone (PPSU), polyamideimide (PAI), polyimide (PI) and the like. PES and PPSU are more preferable.

The solvent used for varnishing may be any solvent that can dissolve the selected resin. However, in order to improve the adhesiveness with the enamel layer that is the base when baking to the enamel layer, the base is used. The same solvent used when baking the enamel layer is preferred.
Further, the thickness of the adhesive layer is preferably 2 to 20 μm, and more preferably 5 to 10 μm. In order to sufficiently heat-bond the adhesive layer and the extrusion-coated resin layer, the resin temperature in the extrusion coating process needs to be equal to or higher than the Tg (glass transition temperature) of the resin selected for the adhesive layer, preferably from Tg Also, a temperature higher by 30 ° C. or higher, more preferably a temperature higher by 50 ° C. or higher than Tg is preferable.

  The present invention will be described below in more detail based on examples, but the present invention is not limited thereto. Of the following Examples and Comparative Examples, Examples 1 to 4 and Comparative Examples 1 to 3 are inventions according to claims 1 and 2, and Examples 5 to 7 and Comparative Examples 4 to 10 are claims 3. Examples 8 to 11 and Comparative Examples 11 to 12 of the present invention are the inventions according to claims 4 and 5, Examples 12 to 13 and Comparative example 13 are the examples and comparative examples of the invention according to claim 6, respectively. It is. Examples 14 and 15 and Comparative Example 14 show the effects of the static friction coefficient of the insulated wire and the coil insertion property.

[Example 1]
A rectangular conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners with a thickness of 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, using a die similar in shape to the shape of the conductor, a polyamideimide resin varnish (trade name HI406 manufactured by Hitachi Chemical Co., Ltd.) is coated on the conductor, and the furnace length is set to 450 ° C. The inside of the baking furnace was passed at a speed of a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed by this single baking process. By repeating this four times, an enamel layer having a thickness of 20 μm was formed, and an enameled wire having a thickness of 20 μm was obtained.
The obtained enameled wire was used as a core wire, and the screw of the extruder used 30 mm full flight, L / D = 20, and a compression ratio of 3. The material was polyetherimide (PEI) (GE plastic: Ultem 1000), and the extrusion temperature conditions were as shown in Table 1. Extrusion coating of resin is performed using an extrusion die to form an extruded coating resin layer having a thickness of 40 μm on the outer side of the enamel layer, and PEI extrusion with a total thickness of 60 μm (the total thickness of the enamel layer and the extruded coating resin layer). An insulated wire made of coated enameled wire was obtained.

[Example 2]
The PEI having a total thickness of 100 μm was formed in the same manner as in Example 1 except that the enamel layer was baked 8 times, an enamel layer having a thickness of 40 μm was formed, and an extrusion coating layer having a thickness of 60 μm was formed thereon. An insulated wire made of an extrusion-coated enameled wire was obtained. Extrusion temperature conditions followed Table 1.

[Example 3]
The PEI having a total thickness of 100 μm was formed in the same manner as in Example 1 except that the enamel layer was baked four times, an enamel layer having a thickness of 20 μm was formed, and an extruded coating layer having a thickness of 80 μm was formed thereon. An insulated wire made of an extrusion-coated enameled wire was obtained. Extrusion temperature conditions followed Table 1.

[Example 4]
An insulated wire made of an ETFE extrusion-coated enameled wire having a total thickness of 100 μm was obtained in the same manner as in Example 2 except that tetrafluoroethylene-ethylene copolymer (ETFE) was used as the extrusion-coated resin. Extrusion temperature conditions followed Table 1.

[Comparative Example 1]
A rectangular conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners with a thickness of 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, using a die similar in shape to the shape of the conductor, a polyamideimide resin varnish (trade name HI406 manufactured by Hitachi Chemical Co., Ltd.) is coated on the conductor, and the furnace length is set to 450 ° C. The inside of the baking furnace was passed at a speed of a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed by this single baking process. By repeating this eight times, an enamel layer having a thickness of 40 μm was formed, and an insulating wire made of an enameled wire having a thickness of 40 μm was obtained.

[Comparative Example 2]
An insulating wire made of enameled wire having a coating thickness of 60 μm was obtained in the same manner as in Comparative Example 1 except that the enamel layer baking process was performed 12 times and an enamel layer having a thickness of 60 μm was formed.

[Comparative Example 3]
An insulating wire made of an enameled wire having a coating thickness of 100 μm was obtained in the same manner as in Comparative Example 2 except that the enamel layer baking process was performed 20 times and an enamel layer having a thickness of 100 μm was formed.

The following evaluation was performed about Examples 1-4 and Comparative Examples 1-3.
(Partial discharge generation voltage)
For the measurement of the partial discharge generation voltage, a partial discharge tester “KPD1050” manufactured by Kikusui Electronics Corporation was used. A sample was prepared in which insulating wires having a square cross-sectional shape were brought into close contact with each other over a length of 150 mm between the long surfaces of the two insulating wires. An electrode was connected between the two conductors, and the voltage was continuously increased while applying an AC voltage of 50 Hz at a temperature of 25 ° C., and the voltage at the time when a partial discharge of 10 pC occurred was read as an actual value. More than 500V was set as the pass.
(Adhesiveness between conductor and enamel layer)
The adhesive strength between the conductor and the enamel layer is determined according to JIS C 3003 enamel wire test method, 8. Adhesion, 8.1b) It was performed in the same manner as the torsion method, and was measured by the number of rotations until the coating floated. More than 15 times were accepted.
The results are shown in Table 1.

  As can be seen from Table 1, the partial discharge start voltages of Examples 1 to 4 and Comparative Examples 1 to 3 are 580 V in Example 1 and Comparative Example 2 in which the total thickness of the enamel layer and the extrusion coating layer is 60 μm, respectively. In Examples 2, 3, 4 and Comparative Example 3 having a total thickness of 100 μm, the voltage was 780 V, 790 V, 810 V and 770 V, respectively. It can be seen that a total thickness of 60 μm is sufficient for the required value of 500 V for the partial discharge start voltage. Further, the slight difference in partial discharge starting voltage between samples having the same total thickness is considered to be caused by the difference in relative dielectric constant of the constituent materials. In Comparative Example 1, since the total thickness was as small as 40 μm, the partial discharge start voltage was 305 V, which did not reach the required 500 V.

Next, looking at the adhesiveness between the conductor and the enamel layer, Example 1 and Example 3 formed a 20 μm enamel layer, so the number of baking was four. Therefore, it is considered that the growth of the thickness of the coating made of copper oxide on the conductor surface could be prevented, and the adhesion between the conductor and the enamel layer was 22 and greatly exceeded the required value of 15. In Examples 2 and 4 and Comparative Example 1, 8 times of baking were performed to form a 40 μm enamel layer. More than 15. In Comparative Examples 2 and 3, enamel layers having a thickness of 60 μm and 100 μm were formed, respectively. Therefore, it was considered that the copper oxide film thickness on the conductor surface was also grown, and the adhesion was poor at 13 and 11.
Thus, in order for the partial discharge generation voltage to reach the required 500 V, a total thickness of 60 μm is necessary, and in order for the adhesiveness to reach the required 15, it is sufficient that the thickness of the enamel layer is 40 μm or less. there were.

[Example 5]
A rectangular conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners with a thickness of 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, using a die similar in shape to the shape of the conductor, a polyamideimide resin varnish (trade name HI406 manufactured by Hitachi Chemical Co., Ltd.) is coated on the conductor, and the furnace length is set to 450 ° C. The inside of the baking furnace was passed at a speed of a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed by this single baking process. By repeating this five times, an enamel layer having a thickness of 25 μm was formed, and an enameled wire having a thickness of 25 μm was obtained.
The obtained enameled wire was used as a core wire, and in the same manner as in Example 1, the screw of the extruder used 30 mm full flight, L / D = 20, and a compression ratio of 3. The material used was polyamideimide (PAI) (Solvay Advanced Polymer: Torlon 4203), and the extrusion temperature conditions were as shown in Table 2. Extrusion coating of resin is performed using an extrusion die to form an extrusion coating resin layer having a thickness of 75 μm on the outer side of the enamel layer, and PAI extrusion with a total thickness (total of the thickness of the enamel layer and the extrusion coating resin layer) of 100 μm An insulated wire made of coated enameled wire was obtained.

[Example 6]
An insulating wire made of PPS extruded coated enameled wire having a total thickness of 100 μm was obtained in the same manner as in Example 5 except that polyphenylene sulfide (PPS) (polyplastics: Fortron 0220A9) was used as the extruded coated resin. Extrusion temperature conditions were performed according to Table 2.

[Example 7]
An insulating wire made of PEEK extrusion-coated enameled wire having a total thickness of 100 μm was obtained in the same manner as in Example 5 except that polyether ether ketone (PEEK) (Victorex MC: PEEK450G) was used as the extrusion-coated resin. . Extrusion temperature conditions were performed according to Table 2.

[Comparative Example 4]
PFA extruded coated enameled wire with a total thickness of 100 μm in the same manner as in Example 5 except that tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) (Asahi Glass: Aflon PFAP-63P) was used as the extruded coated resin. An insulated wire consisting of Extrusion temperature conditions were performed according to Table 2.

[Comparative Example 5]
From an FEP extrusion-coated enameled wire having a total thickness of 100 μm in the same manner as in Example 5 except that tetrafluoroethylene / hexafluoropropylene copolymer (FEP) (Asahi Glass: NEOFLON FEPNP-120) was used as the extrusion-coated resin. An insulated wire was obtained. Extrusion temperature conditions were performed according to Table 2.

[Comparative Example 6]
Tetrafluoroethylene / ethylene copolymer (ETFE) as an extrusion coating resin
An insulating wire made of an ETFE extrusion-coated enameled wire having a total thickness of 100 μm was obtained in the same manner as in Example 5 except that (Asahi Glass: Aflon ETFEC55AXP) was used. Extrusion temperature conditions were performed according to Table 2.

[Comparative Example 7]
An insulating wire made of PMP extrusion-coated enameled wire having a total thickness of 100 μm was obtained in the same manner as in Example 5 except that polymethylpenteneten (PMP) (Mitsui Chemicals: TPX MX004) was used as the extrusion-coated resin. Extrusion temperature conditions were performed according to Table 2.

[Comparative Example 8]
An insulating wire made of an SPS extrusion-coated enameled wire having a total thickness of 100 μm was obtained in the same manner as in Example 5 except that syndiotactic polystyrene (SPS) (Idemitsu Petrochemical: Zalek S101) was used as the extrusion-coated resin. . Extrusion temperature conditions were performed according to Table 2.

[Comparative Example 9]
An insulated wire made of PEI extruded coated enameled wire with a total thickness of 100 μm was obtained in the same manner as in Example 5 except that polyetherimide (PEI) (GE Plastics: Ultem 1000) was used as the extruded coated resin. Extrusion temperature conditions were performed according to Table 2.

[Comparative Example 10]
An insulated wire made of PES extruded coated enameled wire with a total thickness of 100 μm was obtained in the same manner as in Example 5 except that polyethersulfone (PES) (Solvay Advanced Polymer: Radel A300) was used as the extruded coated resin. . Extrusion temperature conditions were performed according to Table 2.

  For measurement of the tensile modulus of the extrusion-coated resin in Examples 5 to 7 and Comparative Examples 4 to 10, a sheet sample having a length of 20 mm, a width of 10 mm, and a thickness of 0.2 mm prepared in advance was used. Using a viscoelastic spectrometer “DMS200” manufactured by Seiko Instruments Inc., the measurement mode is the tensile mode, the frequency is 1 Hz, the strain is 1/1000, and the measurement temperature is measured while changing the heating rate at 5 ° C./min. The tensile modulus at ℃ and 250 ℃ was recorded.

The following evaluation was performed about Examples 5-7 and Comparative Examples 4-10.
(Abrasion resistance (room temperature))
Abrasion resistance is measured according to JIS C 3003 enamel wire test method. Measurements were made on the four corners of a flat wire in the same manner as wear resistance (round wire). 2,000 g or more was accepted.
(Heat aging characteristics (180 ° C))
6. Heat aging characteristics are determined according to JIS C 3003 enamel wire test method. What was wound according to flexibility was visually examined for the presence of cracks in the enamel layer or the extrusion-coated resin layer after being left in a high-temperature bath at 180 ° C. for 300 hours. Those with no abnormalities were accepted.
(Solvent resistance)
The solvent resistance is measured according to JIS C 3003 enamel wire test method, 7. What was wound according to flexibility was immersed in a solvent for 10 seconds, and the surface of the enamel layer or the extrusion-coated resin layer was visually checked for cracks and crazing. As the solvent, three types of acetone, xylene, and styrene were used, and the temperature was measured at two levels of normal temperature and 150 ° C. (the sample was immersed in the solvent in a hot state after being heated at 150 ° C. for 30 minutes). Those with no abnormalities were accepted.
The results are shown in Table 2.

Examples 5, 6, and 7 and Comparative Examples 8, 9, and 10 all have a tensile elastic modulus at 25 ° C. exceeding 1000 MPa. And these were 2000 g or more of abrasion resistance evaluated at normal temperature, and they were very excellent in abrasion resistance. On the other hand, Comparative Examples 4, 5, 6, and 7 all have a tensile elastic modulus at 25 ° C. of less than 1000 MPa. And these were somewhat inferior in wear resistance characteristics to Examples 5-7. From these results, it is considered that high rigidity at normal temperature leads to the effect of preventing wear.
In Examples 5, 6, and 7, and Comparative Examples 4, 5, and 6, the tensile elastic modulus at 250 ° C. exceeds 10 MPa. These were excellent in heat aging characteristics evaluated at 180 ° C. On the other hand, Comparative Examples 7, 8, 9, and 10 have a tensile elastic modulus at 250 ° C. of less than 10 MPa. And these heat-resistant aging characteristic evaluation results became a little inferior compared with Examples 5-7. From these results, it can be said that the heat aging characteristic is a kind of heat resistance, and a correlation with the tensile elastic modulus at a high temperature, for example, 250 ° C. was obtained.
It was also confirmed that Examples 5, 6, and 7 satisfying these conditions had very excellent characteristics with respect to the solvent resistance evaluated at room temperature and 150 ° C.
That is, it was found that a resin material having a tensile elastic modulus of 1000 MPa or more at room temperature and 10 MPa or more at 250 ° C. would be excellent in terms of three characteristics of wear resistance, heat aging characteristics, and solvent resistance. .

[Example 8]
A rectangular conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners with a thickness of 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, using a die similar in shape to the shape of the conductor, a polyamideimide resin varnish (trade name HI406 manufactured by Hitachi Chemical Co., Ltd.) is coated on the conductor, and the furnace length is set to 450 ° C. The inside of the baking furnace was passed at a speed of a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed by this single baking process. By repeating this five times, an enamel layer having a thickness of 25 μm was formed, and an enameled wire was obtained.
Next, polyphenylsulfone resin (PPSU) (Solvay Advanced Polymer: Radel R5800) is dissolved in N-methyl-2-pyrrolidone (NMP), and a resin varnish made into a 20 wt% solution is similar to the shape of the conductor. Using a die, the enameled wire was coated and passed through a baking furnace having a furnace length of 8 m set at 450 ° C. at a speed that would result in a baking time of 15 seconds. By repeating this twice, a thickness of 10 μm was obtained. An adhesive layer was formed (the thickness formed in one baking process was 5 μm), and an enameled wire with an adhesive layer having a thickness of 35 μm was obtained.
The obtained enameled wire with an adhesive layer was used as a core wire, and the same screw as that used in Example 1 was used. As the screw of the extruder, 30 mm full flight, L / D = 20, and a compression ratio of 3 were used. The material is polyetherimide (PEI) (GE Plastic: Ultem 1000), and the extrusion temperature conditions are as shown in Table 3. Extrusion coating of the resin is performed using an extrusion die to form an extrusion coating resin layer having a thickness of 65 μm on the outside of the adhesive layer, and the total thickness (the total thickness of the enamel layer, the adhesive layer, and the extrusion coating resin layer) is 100 μm. An insulating wire made of PEI extrusion-coated enameled wire with an adhesive layer was obtained.

[Example 9]
An insulated wire made of a PPS extruded coated enameled wire with an adhesive layer having a total thickness of 100 μm was obtained in the same manner as in Example 8 except that PPS was used as the extruded coated resin. Table 3 shows the extrusion temperature conditions.

[Example 10]
An insulating wire made of a PEI extrusion-coated enameled wire with an adhesive layer having a total thickness of 100 μm was obtained in the same manner as in Example 8 except that the resin used as the resin varnish was PES. Table 3 shows the extrusion temperature conditions.

[Example 11]
An insulated wire made of a PPS extruded coated enameled wire with an adhesive layer having a total thickness of 100 μm was obtained in the same manner as in Example 10 except that PPS was used as the extruded coated resin. Table 3 shows the extrusion temperature conditions.

[Comparative Example 11]
A rectangular conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners with a thickness of 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, using a die similar in shape to the shape of the conductor, a polyamideimide resin varnish (trade name HI406 manufactured by Hitachi Chemical Co., Ltd.) is coated on the conductor, and the furnace length is set to 450 ° C. The inside of the baking furnace was passed at a speed of a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed by this single baking process. By repeating this five times, an enamel layer having a thickness of 25 μm was formed, and an enameled wire was obtained.
The obtained enameled wire was used as a core wire, and in the same manner as in Example 1, the screw of the extruder used 30 mm full flight, L / D = 20, and a compression ratio of 3. The material is polyetherimide (PEI) (GE Plastic: Ultem 1000), and the extrusion temperature conditions are as shown in Table 3. Extrusion coating of the resin was performed using an extrusion die to form an extrusion-coated resin layer having a thickness of 75 μm on the outside of the adhesive layer, and an insulating wire made of PEI extrusion-coated enameled wire with an adhesive layer having a total thickness of 100 μm was obtained.

[Comparative Example 12]
An insulating wire made of a 100 μm PPS extruded coated enameled wire was obtained in the same manner as Comparative Example 11 except that PPS was used as the extruded coated resin. Table 3 shows the extrusion temperature conditions.

The following evaluation was performed about Examples 8-11 and Comparative Examples 11-12.
For the bending evaluation, edgewise bending with a bending radius of 1, 2, 3, 4, 5 mm was performed, and it was visually determined whether or not there were wrinkles inside the bending arc.
Moreover, the partial discharge generation voltage of the bent portion was measured using a partial discharge tester “KPD1050” manufactured by Kikusui Electronics Corporation. Cover the bent part of the insulated wire with metal foil (aluminum, etc.), and at a temperature of 25 ° C, the voltage is continuously increased while applying an AC voltage of 50 Hz between the wire conductor and the metal foil. The voltage at the time of occurrence was read as an effective value.

  In the extrusion temperature conditions shown in Tables 1 to 3, C1, C2, and C3 indicate the three zones in which the temperature control in the cylinder portion of the extruder is performed separately from the material input side. H indicates the head behind the cylinder of the extruder. D indicates a die at the tip of the head.

Looking at the bending evaluation results, each of Examples 8, 9, 10, and 11 is a sample having an adhesive layer, and the combination of the resin used as the adhesive layer and the resin used as the extrusion coating resin layer is changed. However, no wrinkle was observed in any example even at the most severe bending radius of 1 mm. Further, Comparative Examples 11 and 12 were the same extrusion coated resin as Examples 8, 9, 10 and 11, but were samples having no adhesive layer, and thus wrinkles were generated as the bending radius became severe. This is considered to be caused by the adhesive strength between the enamel layer and the extrusion coating layer, and the difference between the sample having the adhesive layer and the sample not having the adhesive layer clearly appears.
Next, looking at the partial discharge generation voltage at the bent portion, all of Examples 8, 9, 10, and 11 were 480 V regardless of the bending radius. This is exactly the same as the measured value for the sample in a straight line state before bending, and wrinkles were not generated by bending, so it is considered that there was no effect on the partial discharge generation voltage. Further, when the results of Comparative Examples 11 and 12 are seen, in the samples where the bending radius is small and wrinkles are generated, the amount of decrease is more noticeable as the partial discharge generation voltage is lower than 480 V and the bending radius is further decreased. The wrinkles of the extrusion coating layer are considered to have influenced the partial discharge generation voltage. Thus, the samples of Examples 8 to 11 having the adhesive layer were excellent in bendability even under very severe conditions.

[Example 12]
A flat conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners at 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, a polyamide imide resin varnish (trade name H1406, manufactured by Hitachi Chemical Co., Ltd.) was coated on a copper body using a die similar to the shape of the conductor, and the furnace length was set to 450 ° C. Then, the enamel having a thickness of 5 μm was formed in this one baking process. By repeating this four times, an enamel layer having a thickness of 20 μm was formed, and an enameled wire having a thickness of 20 μm was obtained. The obtained enameled wire was used as a core wire, and the screw of the extruder used 30 mm full flight, L / D = 20, and a compression ratio of 3. The material used was polyphenylene sulfide (PPS) (trade name ML-320P, manufactured by Dainippon Ink Co., Ltd.), and the extrusion temperature conditions were as shown in Table 4. Extrusion coating of the resin is performed on the conductor using a die whose flat surface is thicker than the edge surface, using an extrusion die to form an extruded coating resin with a flat surface of 75μm and an edge surface of 40μm outside the enamel layer. An insulating wire made of a PPS extruded coated enameled wire having a thickness (total thickness of enamel layer and extrusion coated resin layer) of 100 μm on the flat surface and 65 μm on the edge surface was obtained. The flat surface mentioned here refers to a pair of long sides among two opposing sides of a pair of rectangular cross sections. Further, the edge surface refers to a pair of short sides of two sides facing each other.

[Example 13]
The flat surface is 40 μm on the outer side of the enamel layer, the edge surface is the same as in Example 12 except that the extrusion is applied to the conductor using a die having a thicker edge surface than the flat surface. Formed an extrusion coated resin with a thickness of 75 μm, and an insulated wire consisting of PPS extruded coated enameled wire with a total thickness (total thickness of enamel layer and extrusion coated resin layer) of 65 μm on the flat surface and 100 μm on the edge surface was obtained. . Extrusion temperature conditions are as shown in Table 4.

[Comparative Example 13]
An insulated wire made of PPS extrusion-coated enameled wire with a total thickness of 100 μm on both the edge surface and the flat surface was obtained in the same manner as in Example 12 except that a similar die having a conductor cross-sectional shape was used. Extrusion temperature conditions are as shown in Table 4.

The following evaluations were performed on Examples 12 to 13 and Comparative Example 13.
For the measurement of the partial discharge generation voltage, a partial discharge tester “KPD1050” manufactured by Kikusui Electronics Corporation was used. A sample was produced in which insulating wires having a square cross-sectional shape were brought into close contact with each other over the length of 150 mm between the long sides of the two insulating wires over a length of 150 mm. An electrode was connected between the two conductors, and the voltage was continuously increased while applying an AC voltage of 50 Hz at a temperature of 25 ° C., and the voltage at the time when a partial discharge of 10 pC occurred was read as an effective value. More than 500V was set as the pass.
In addition, the space factor is assumed to be a square motor slot with a dimension that can provide a cross-section that is not excessive or deficient with respect to the overall cross-sectional shape in which the flat surfaces of two or more wires of the present invention are closely adhered to each other. The ratio of the total area of the conductor to the slot cross-sectional area.
Specifically, for a wire having a flat-side outer dimension a and an edge-side outer dimension b, the square cross-sectional area of the assembly obtained by bringing the two flat surfaces into close contact with each other is (2ab) The conductor area (total of two wires) of the cross section of the original two wires occupying this is expressed as a percentage.
The results are shown in Table 4.

  As is clear from Table 4, regarding the partial discharge start voltages of Examples 12 to 13 and Comparative Example 13, both Examples 12 to 13 and Comparative Example 13 were 900V. If the thickness of the film on the pair of surfaces where discharge occurs is a predetermined thickness, the partial discharge generation voltage can be maintained even if the thickness of the other pair of facing surfaces is smaller than that.

  Next, looking at the space factor, the space factor of Examples 12 to 13 was 86%, and that of Comparative Example 13 was 83%. When trying to reduce the partial discharge, the coating film becomes thicker, so there is a problem that the space factor is reduced. The momentum could be raised.

[Example 14]
A flat conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners at 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, a polyamide imide resin varnish (trade name H1406, manufactured by Hitachi Chemical Co., Ltd.) was coated on a copper body using a die similar to the shape of the conductor, and the furnace length was set to 450 ° C. The inside of the baking furnace was currencyd at a speed that would result in a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed in this single baking process. By repeating this five times, an enamel layer having a thickness of 25 μm was formed, and an enameled wire having a thickness of 25 μm was obtained. The obtained enameled wire was used as a core wire, and the screw of the extruder used 30 mm full flight, L / D = 20, and a compression ratio of 3. The material used was polyphenylene sulfide (PPS) (polyplastics: Fortron 0220A9), and the extrusion temperature conditions were as shown in Table 4. Extrusion coating of resin is performed on the conductor using an extrusion die to form a 75μm PPS extrusion coating resin on the outside of the enamel layer, and the total thickness (the total thickness of the enamel layer and the extrusion coating resin layer) is 100μm. An insulated wire made of PPS extrusion coated enameled wire was obtained.

[Example 15]
Insulated wire made of PEI extrusion-coated enameled wire with a total thickness of 100 μm in the same manner as in Example 14 except that polyetherimide (PEI) (product name: ULTEM 1000) was used for the extrusion-coated resin layer Got. The extrusion temperature was in accordance with Table 5.

[Comparative Example 14]
A rectangular conductor (copper having an oxygen content of 15 ppm) having a chamfer radius r = 0.5 mm at four corners with a thickness of 1.8 × 2.5 mm (thickness × width) was prepared. For the formation of the enamel layer, using a die similar in shape to the shape of the conductor, a polyamideimide resin varnish (trade name HI406 manufactured by Hitachi Chemical Co., Ltd.) is coated on the conductor, and the furnace length is set to 450 ° C. The inside of the baking furnace was passed at a speed of a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed by this single baking process. By repeating this 20 times, an enamel layer having a thickness of 100 μm was formed, and an insulating wire made of an enameled wire having a thickness of 100 μm was obtained.

The following evaluation was performed on Examples 14 to 15 and Comparative Example 14.
The evaluation of the static friction coefficient is to measure the static friction coefficient between enameled wires. The measurement method is to stretch two wires that have been stretched 0.5% in advance on the table in parallel, and fix both ends with holder pins. When a load with two wires stretched in parallel is placed on top of the two wires so that they cross each other, a weight is gradually placed on a tray connected via a pulley from the load and the load begins to slide. I read the weight. The load is 100 g.

  As is apparent from Table 5, the static friction coefficients of Examples 14 to 15 are 0.19 and 0.17, and that of Comparative Example 15 is 0.25. The outer layers of Examples 14 to 15 are extrusion-coated resins, and the comparative example is an enamel-baked layer. The wires of the extrusion-coated resins have a low coefficient of static friction, and the insertability of the wires during motor processing is also good.

Claims (6)

  It has at least one enamel baked layer on the outer periphery of the conductor and at least one extruded coated resin layer on the outer side thereof, and the total thickness of the enamel baked layer and the extruded coated resin layer is 60 μm or more. Insulated wire characterized by.   2. The insulated wire according to claim 1, wherein the enamel baking layer has a thickness of 50 [mu] m or less.   The insulated wire according to claim 1 or 2, wherein the extrusion-coated resin layer is made of a resin material having a tensile elastic modulus at 25 ° C of 1000 MPa or more and a tensile elastic modulus at 250 ° C of 10 MPa or more.   An insulated wire having at least one enamel-baked layer on the outer periphery of a conductor having a rectangular cross section and at least one extrusion-coated resin layer on the outside thereof, provided on a pair of two opposing sides of the cross section The insulated wire according to any one of claims 1 to 3, wherein a thickness of the extruded coated resin layer is different from a thickness of the extruded coated resin layer provided on another pair of opposing two sides.   An adhesive layer is provided between the enamel baked layer and the extrusion-coated resin layer, and the adhesive force between the enamel baked layer and the extrusion-coated resin layer is reinforced using the adhesive layer as a medium. The insulated wire of any one of 1-4.   On the outer periphery of the enamel baking layer, a varnished resin is baked to form an adhesive layer, and then contacted with an extrusion coating resin in a molten state at a temperature higher than the glass transition temperature of the resin used for the adhesive layer 6. The method of manufacturing an insulated wire according to claim 5, wherein the enamel baking layer and the extrusion-coated resin layer are thermally fused.