Insulated wire and method for manufacturing same, and coil, rotating electric machine, and electrical / electronic device using same

Abstract

An insulated wire having a conductor and a resin coating layer covering the periphery of the conductor, in which the conductor is an aluminum conductor surface-treated by CO2 plasma, and at least a portion of the resin coating layer in contact with the conductor contains at least one of a polyaryletherketone resin and a polyphenylene sulfide resin.

Description

Technical Field

[0001] The present invention relates to an insulated wire and a method for producing the same, and a coil, a rotating electrical machine, and an electric / electronic device using the insulated wire. Background Art

[0002] In inverter-related devices (coils for electric / electronic devices such as high-speed switching elements, inverter motors, and transformers), insulated wires having an insulating coating made of insulating resin provided around a conductor are used as magnetic conductors.

[0003] Insulated wires used in miniaturized electrical / electronic equipment require an insulating film to cover the conductor with high adhesion. That is, in such equipment, the insulated wire is used by pressing it into a narrow part for winding. For example, in a rotating motor or transformer, the number of coils that can be placed in the slot of the stator core has a great influence on its performance. Therefore, the insulated wire is bent with a complex and small bending radius. At this time, if the adhesion between the conductor and the coating resin layer is insufficient, the insulating film will peel off the conductor.

[0004] In recent years, the demand for lightweight electrical and electronic equipment such as motors has gradually increased. Therefore, the need for insulated wires using aluminum, which is lighter than copper, as conductors is increasing. The surface of aluminum conductors is covered with a chemically stable oxide film, and the adhesion between aluminum conductors and insulation coatings is poorer than that between copper conductors, so technologies have been developed to increase the adhesion strength between aluminum conductors and insulation coatings.

[0005] For example, Patent Document 1 describes that: a thermoplastic resin having a diphenyl ether group is formed on the outer periphery in contact with a conductor made of aluminum or an aluminum alloy, and the storage modulus of the thermoplastic resin at 250° C. is 0.8×10 5 ~1.1×10 6 Pa insulation coating, thereby improving the adhesion between the conductor and the insulation coating. In addition, Patent Document 2 discloses an insulation coated aluminum electric wire, which has an insulation coating layer containing a resin having at least a benzene ring and an imide ring, and is coated with two or more insulation coating layers. In this aluminum electric wire, an insulation coating layer composed of a resin having a high imide ring content molar ratio is provided in the innermost layer, and by making the imide ring content molar ratio between the coating resin layers have a specific relationship, it shows excellent adhesion with the aluminum conductor, adhesion between the insulation coating resin layers, wear resistance, and insulation after processing.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2021-157956

[0009] Patent Document 2: Japanese Patent Application Publication No. 2016-021324 Summary of the invention

[0010] Problems to be solved by the invention

[0011] As described above, it is known that the adhesion between the aluminum conductor and the insulation coating can be improved by using a specific resin type as the resin coating layer (insulation coating) covering the outer periphery of the aluminum conductor. On the other hand, it is known that polyaryletherketone (PAEK) resin and polyphenylene sulfide (PPS) resin, which are commonly used as thermoplastic resins for forming insulation coatings, have poor adhesion strength with the conductor when they are directly extruded and coated around the aluminum conductor.

[0012] The present invention aims to provide an insulated wire and a method for manufacturing the same, as well as a coil, a rotating electrical machine, and an electrical / electronic device using the insulated wire, wherein the insulated wire uses an aluminum conductor as a conductor, uses a PAEK resin or a PPS resin as a material for a resin coating layer directly covering the conductor, and has excellent adhesion between the conductor and the resin coating layer, exhibits a high dielectric breakdown voltage, and further has excellent heat resistance.

[0013] Means for solving problems

[0014] The present inventors have conducted research to solve the above-mentioned problems and have found that the adhesion between the aluminum conductor and the resin coating layer containing PAEK resin or PPS resin directly covering the conductor is significantly improved by performing CO2 plasma treatment on the surface of the aluminum conductor. The present invention has been completed through further research based on these findings.

[0015] That is, the above-mentioned problems of the present invention are solved by the following means. [1]

[0017] An insulated wire having a conductor and a resin coating layer covering the conductor, wherein:

[0018] The above conductor is an aluminum conductor that has been surface treated by CO2 plasma.

[0019] At least a portion of the resin coating layer in contact with the conductor includes at least one of a polyaryletherketone resin and a polyphenylene sulfide resin. [2]

[0021] In the insulated wire according to the above [1], the polyaryletherketone resin includes at least one of a polyetheretherketone resin, a polyetherketoneketone resin, and a polyetherketone resin. [3]

[0023] In the insulated wire according to the above [1] or [2], an arithmetic mean roughness Sa of the surface of the conductor is 3 μm or less. [4]

[0025] The insulated wire as described in any one of [1] to [3] above, wherein the adhesion strength of the resin coating layer to the conductor is 1.0 N / mm or more. [5]

[0027] The insulated wire as described in any one of [1] to [4] above, wherein after the insulated wire is heat treated at 220° C. for 100 hours, the adhesion strength of the resin coating layer to the conductor is 1.0 N / mm or more. [6]

[0029] A coil using the insulated wire according to any one of [1] to [5] above. [7]

[0031] A rotating electrical machine or an electrical / electronic device having the coil described in [6] above. [8]

[0033] A method for producing an insulated wire, which is the method for producing an insulated wire according to any one of [1] to [5] above, comprising the following steps:

[0034] A resin coating layer containing at least one of a polyaryletherketone resin and a polyphenylene sulfide resin is formed at least in a portion in contact with the aluminum conductor by extruding a coating resin onto the aluminum conductor surface treated by CO2 plasma. [9]

[0036] In the method for producing an insulated wire as described in the above-mentioned [8], the conductor is surface-treated by CO2 plasma after preheating.

[0037] Effects of the Invention

[0038] The insulated wire of the present invention has excellent adhesion between the aluminum conductor and the resin coating layer, has a high insulation breakdown voltage, and also has excellent heat resistance. In addition, according to the method for manufacturing the insulated wire of the present invention, an insulated wire having such excellent performance can be obtained. In addition, according to the present invention, a coil, a rotating electric machine, and an electrical / electronic device using the insulated wire having such excellent performance are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic cross-sectional view showing one embodiment of the insulated wire of the present invention.

[0040] Figure 2This is an exploded perspective schematic diagram showing a preferred embodiment of a stator used in the electric / electronic device of the present invention.

[0041] Figure 3 This is a schematic perspective view showing a preferred embodiment of a stator used in the electric / electronic device of the present invention. DETAILED DESCRIPTION

[0042] [Insulated wire]

[0043] The insulated wire of the present invention comprises a conductor and a resin coating layer covering the periphery of the conductor and functioning as an insulating film. The conductor is an aluminum conductor surface-treated by CO2 plasma, and at least a portion of the resin coating layer in contact with the conductor contains at least one of a PAEK resin and a PPS resin. Typically, when the resin coating layer is a single-layer structure, the resin coating layer is composed of at least one of a PAEK resin and a PPS resin, and when the resin coating layer is a multi-layer structure composed of two or more different resin layers, at least the innermost layer in contact with the conductor is composed of at least one of a PAEK resin and a PPS resin.

[0044] Therefore, the insulated wire of the present invention preferably includes the conductor described above and a resin layer that is in contact with the conductor and contains at least one of a PAEK resin and a PPS resin.

[0045] In the present invention, the "aluminum conductor" refers to a conductor formed of aluminum or an aluminum alloy. In this specification, the aluminum conductor may also be simply referred to as a "conductor".

[0046] Figure 1 1 is a cross-sectional view of one embodiment of the insulated wire of the present invention. The insulated wire 1 includes a conductor 11 and a resin coating layer 12 as an insulating film formed on the outer peripheral surface of the conductor 11 . Figure 1 In the embodiment, the cross-sectional shape of the conductor 11 is a rectangular (square shape). The cross-sectional shape of the insulated wire 1 of the present invention is preferably similar to that of the conductor 11.

[0047] Next, the structure of the insulated wire of the present invention will be described in detail.

[0048] <Conductor>

[0049] The aluminum conductor constituting the insulated wire of the present invention is subjected to surface treatment by CO2 plasma. By subjecting the surface of the aluminum conductor to CO2 plasma treatment, the conductor surface is modified, and the adhesion with PAEK resin and PPS resin, which originally have poor adhesion with the aluminum conductor, can be significantly improved. Therefore, even if a resin coating layer containing PAEK resin or PPS resin is provided in contact with the aluminum conductor, the adhesion between the conductor and the resin coating layer can be sufficiently improved.

[0050] As the conductor used in the present invention, aluminum or aluminum alloys that have been conventionally used as conductors of insulated wires can be widely used.

[0051] There are no particular limitations on the aluminum or aluminum alloy as long as it can be used as a conductor of an insulated wire. For example, A1050 (aluminum purity of 99.50% or more), A1070 (aluminum purity of 99.70% or more), A1080 (aluminum purity of 99.80% or more) which are 1000 series pure aluminum, or A6101 which is a 6000 series Al-Mg-Si series aluminum alloy, etc. can be appropriately used. In addition, the following may be appropriately used: an Al-Fe aluminum alloy containing 0.2 to 1.0 mass % of Fe, 0.02 to 0.3 mass % of Si, further containing a total of 0.001 to 0.01 mass % of Ti and V, with the remainder consisting of Al and inevitable impurities; and an aluminum alloy (MSAL) containing 0.05 to 0.3 mass % of Fe, 0.05 to 0.3 mass % of Cu, 0.05 to 0.3 mass % of Mg, 0.02 to 0.3 mass % of Si, further containing a total of 0.001 to 0.01 mass % of Ti and V, with the remainder consisting of Al and inevitable impurities; etc.

[0052] For example, when the insulated wire of the present invention is used for a rotating electric machine, the conductor used for the insulated wire of the present invention is preferably pure aluminum having a purity of 99.00% or more that can obtain a high current value.

[0053] The conductor used in the insulated wire of the present invention is previously subjected to a surface treatment by CO2 plasma. By irradiation with CO2 plasma, specific functional groups are introduced to the surface of the conductor (when an oxide film is formed on the surface of the aluminum conductor, the surface of the oxide film), and it is considered that the surface state has excellent affinity with the PAEK resin and the PPS resin, and the adhesion between the conductor and the resin coating layer is improved. The above functional groups may not be clear, but in principle it is considered that functional groups such as hydroxyl, carbonyl, aldehyde, and carboxyl groups are introduced by plasma irradiation. In the present invention, by CO2 plasma treatment of the surface of the aluminum conductor, the proportion of aluminum hydroxide or ester bonds on the surface of the aluminum conductor increases, which is considered to be one of the reasons for the unexpected improvement of the adhesion with the above PAEK resin and PPS resin.

[0054] In addition, in the plasma irradiation step, atoms present in the CO2 plasma irradiation nozzle are attached to the surface of the above-mentioned aluminum conductor together with the CO2 plasma irradiation. As atoms from the above-mentioned irradiation nozzle, there can be cited various atoms such as Cr atoms, Fe atoms, Ni atoms, and Cu atoms. These atoms can exist on the conductor surface within a range that does not affect the adhesion between the aluminum conductor and the resin coating layer, and can also be removed from the conductor surface by operations such as cleaning.

[0055] Regarding the above-mentioned aluminum conductor after CO2 plasma irradiation, the wettability of the conductor surface is improved. On the surface of the above-mentioned aluminum conductor, the contact angle (θ) with water is preferably 15° or less, more preferably 13° or less, and further preferably 11° or less. In addition, the surface free energy (Surface Free Energy, SFE) is preferably 70mN / m or more, more preferably 75mN / m or more, and further preferably 79mN / m or more. It should be noted that the dispersion component (dispersion force) of the surface free energy is preferably 43mN / m or more, more preferably 45mN / m or more, and further preferably 49mN / m or more.

[0056] When the aluminum conductor used in the present invention is subjected to CO2 plasma treatment, the plasma irradiation conditions can be appropriately set so that the conductor after the plasma treatment has the above-mentioned characteristics. The specific conditions of the plasma treatment are described below.

[0057] It should be noted that in the present invention, the above-mentioned preferred ranges of the contact angle between the conductor surface and water, the surface free energy and the dispersion component thereof are all preferred ranges for the aluminum conductor after the plasma treatment and before the formation of the resin coating layer.

[0058] In order to improve the adhesion strength between the metal substrate and the resin raw material, it is known that a method of roughening the surface of the metal substrate by laser treatment is used. On the other hand, when this method is applied to an aluminum conductor, laser particles are generated by laser treatment, and the particles are mixed into the resin coating layer during the manufacture of the insulated wire, which also becomes a major cause of reducing the insulation breakdown voltage.

[0059] In the insulated wire of the present invention, the adhesion with the resin coating layer can be improved by CO2 plasma treatment without excessively increasing the surface roughness of the aluminum conductor. For the conductor in the insulated wire of the present invention, from the perspective of increasing the insulation breakdown voltage, the arithmetic mean roughness [Sa; ISO standard] of the surface is preferably 3 μm or less, more preferably 2.5 μm or less, and further preferably 2 μm or less. It should be noted that the arithmetic mean roughness of the above-mentioned conductor can be determined, for example, by measuring the conductor surface at a magnification of 400 times using a laser microscope VK-X250 manufactured by Keyence, according to the surface roughness measurement method (ISO 25178 surface properties).

[0060] It should be noted that in the present invention, the preferred range of the arithmetic mean roughness of the conductor surface is a preferred range for the aluminum conductor after the plasma treatment of the aluminum conductor and before the formation of the resin coating layer.

[0061] The cross-sectional shape orthogonal to the length direction of the conductor used in the present invention is not particularly limited. For example, conductors with circular or rectangular (square) cross-sectional shapes can be cited. In the present invention, conductors with rectangular cross-sectional shapes, i.e., square conductors, are preferred. Compared with circular conductors, conductors with rectangular cross-sectional shapes have a higher space factor of the stator core relative to the slots during winding. Therefore, it is preferred for applications where multiple insulated wires are assembled in a certain narrow space. As a preferred example of the conductor used in the present invention, Figure 1 The case where the conductor has a rectangular cross section (square shape) is shown.

[0062] In terms of suppressing partial discharge from the corners (corners), the conductor having a rectangular cross-sectional shape is preferably as follows: Figure 1 The shape shown is provided with chamfers (curvature radius r) at four corners. The curvature radius r is preferably 0.6 mm or less, more preferably 0.2 to 0.4 mm.

[0063] The size of the conductor is not particularly limited. In the case of a square conductor, in a rectangular cross-sectional shape, the width (long side) is preferably 1.0 to 7.0 mm, more preferably 1.4 to 4.0 mm, and the thickness (short side) is preferably 0.4 to 3.0 mm, more preferably 0.5 to 2.5 mm. The ratio of the length of the width (long side) to the thickness (short side) (thickness: width) is preferably 1:1 to 1:4. On the other hand, in the case of a conductor with a circular cross-sectional shape, the diameter is preferably 0.3 to 3.0 mm, more preferably 0.4 to 2.7 mm.

[0064] <Resin coating layer>

[0065] The resin coating layer in the insulated wire of the present invention contains at least one thermoplastic resin selected from PAEK resin and PPS resin at the portion in contact with the conductor. As described above, the resin coating layer may be a single layer or a multilayer structure of two or more layers.

[0066] The thickness of the resin coating layer is not particularly limited, and may be 20 to 200 μm, 50 to 100 μm, or 20 to 50 μm.

[0067] In the present invention or this specification, "polyaryletherketone (PAEK) resin" refers to a resin composed of a polymer having a phenylene group, an ether group that bonds the phenylene groups together, and a carbonyl group that bonds the phenylene groups together. The phenylene group may be unsubstituted or may have a substituent within a range that does not impair the effects of the present invention. Examples of such a substituent include an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) and the like.

[0068] Preferred PAEK resins in the present invention include, for example, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, polyetherketoneketone (PEKK) resin, polyetheretherketoneketone (PEEKK) resin, polyetherketoneetherketoneketone (PEKEKK) resin, and polyetherketoneester resin. The PAEK resin used in the resin coating layer of the present invention may be used alone or as a mixture of two or more resin components. The PAEK resin is preferably a resin comprising at least one of polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, and polyetherketoneketone (PEKK) resin.

[0069] The PAEK resin may be crystalline (semi-crystalline) or amorphous.

[0070] Specific examples of the above-mentioned PAEK resin and PPS resin that can be used in the resin coating layer of the present invention include, for example, KT-880 (trade name) manufactured by Solvay Corporation can be cited as a PEEK resin, NovaSpire (trade name) manufactured by Solvay Corporation can be cited as a PEKK resin, VICTREX HT (trade name) manufactured by VICTREX Corporation and other commercially available products can be cited as a PEK resin, and Susteel (trade name) manufactured by Tosoh Corporation and other commercially available products can be cited as a PPS resin.

[0071] In the case of a multilayer structure in which the insulating coating is composed of two or more different resin coating layers, the innermost resin coating layer in contact with the conductor is preferably composed of the above-mentioned PAEK resin or PPS resin. In this case, the constituent material of the resin coating layers other than the innermost layer is not particularly limited, and a general-purpose thermosetting resin or thermoplastic resin can be applied.

[0072] For example, as thermosetting resins, there can be mentioned thermosetting resins having imide bonds such as polyimide (PI), polyamideimide (PAI) and polyesterimide (PEsI), or polyurethane (PU), thermosetting polyester (PEst), H-type polyester (HPE), polyimide hydantoin-modified polyester, polyhydantoin, polybenzimidazole, melamine resin or epoxy resin. In addition, as thermoplastic resins, in addition to general engineering plastics such as polyamide (PA) (nylon), polyetherimide (PEI), polyacetal (POM), polycarbonate (PC), polyphenylene ether (including modified polyphenylene ether), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and ultra-high molecular weight polyethylene, polysulfone (PSF), polyethersulfone (PES), polyphenylene sulfide (PPS), polyarylate (U-Polymer), polyamide-imide, polyetherketone (PEK), polyaryletherketone (PAEK), tetrafluoroethylene-ethylene copolymer (ETFE), polyether Polyether ether ketone (PEEK) (including modified polyether ether ketone (modified PEEK)), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), thermoplastic polyimide resin (TPI), polyamide-imide (PAI), liquid crystal polyester and other super engineering plastics, as well as polymer alloys using polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) as base resins, ABS / polycarbonate, nylon 6,6, aromatic polyamide resin (aromatic PA), polyphenylene ether / nylon 6,6, polyphenylene ether / polystyrene, polybutylene terephthalate / polycarbonate and other polymer alloys containing the above engineering plastics.

[0073] The above-mentioned resin coating layer may contain various additives such as bubble nucleating agents, antioxidants, antistatic agents, UV inhibitors, light stabilizers, fluorescent brighteners, pigments, dyes, compatibilizers, lubricants, reinforcing agents, flame retardants, crosslinking agents, crosslinking aids, plasticizers, thickeners, viscosity reducers and elastomers within the range that does not impair the effect of the present invention.

[0074] (Sealing strength)

[0075] As described above, the insulated wire of the present invention uses an aluminum conductor treated with CO2 plasma and forms an insulating coating layer containing PAEK resin or PPS resin in contact with the conductor, thereby achieving excellent adhesion between the conductor and the resin coating layer. In the insulated wire of the present invention, the adhesion strength (adhesion force) between the conductor and the resin coating layer is preferably 1.0 N / mm or more, more preferably 1.5 N / mm or more, and further preferably 2.0 N / mm or more. In addition, the adhesion strength is usually 10.0 N / mm or less, and may be 5.0 N / mm or less.

[0076] In addition, the insulated wire of the present invention has excellent heat resistance and can maintain excellent adhesion strength between the conductor and the resin coating layer even after heat treatment. For example, even when the insulated wire of the present invention is heat treated at 220°C for 100 hours, the adhesion strength between the conductor and the resin coating layer can be 1.0 N / mm or more, 1.5 N / mm or more, or 2.0 N / mm or more. In addition, the adhesion strength is usually 10.0 N / mm or less, and can also be 5.0 N / mm or less.

[0077] It should be noted that the adhesion strength between the aluminum conductor and the resin coating layer can be determined, for example, by the method described in the examples. In addition, since the resin coating layer is thin, in the adhesion strength measurement test described in the examples, when the resin coating layer is broken and the adhesion strength cannot be measured, it is preferably measured by the surface and interface cutting analysis system (Surface And Interface Cutting Analysis System, SAICAS) method. For example, for an insulated wire with a resin coating layer of less than 50 μm, when measuring the adhesion strength between the conductor and the resin coating layer, the adhesion strength can be measured using a surface and interface cutting analysis system device (DN-20S, manufactured by DAIPLA WINTES) in a constant speed mode of horizontal speed: 2 μm / sec, extrusion load: 20N, vertical speed: 0.2 μm / sec, and pressing load: 10N.

[0078] (Dielectric Breakdown Voltage)

[0079] In the insulated wire of the present invention, the breakdown voltage is preferably 100 kV / mm or more, more preferably 120 kV / mm or more, and even more preferably 130 kV / mm or more. The breakdown voltage can be determined by the method described in the Examples.

[0080] [Manufacturing method of insulated electric wire]

[0081] (CO2 plasma treatment)

[0082] In the manufacturing method of the insulated wire of the present invention, an aluminum conductor treated with CO2 plasma is used as the conductor of the insulated wire. The surface of the aluminum conductor can be modified by passing CO2 gas through electrodes and applying high frequency and high voltage to generate CO2 plasma on the surface of the aluminum conductor under atmospheric pressure, or by irradiating the generated CO2 plasma onto the surface of the aluminum conductor.

[0083] In the raw material gas of the plasma gas used for CO2 plasma irradiation, the CO2 gas concentration is usually 5 Vol% or more (5 volume %), preferably 50 Vol% or more, more preferably 70 Vol% or more, further preferably 80 Vol% or more, further preferably 90 Vol% or more, further preferably 95 Vol% or more. The CO2 gas concentration may also be 100 Vol%.

[0084] The various conditions of CO2 plasma treatment can be appropriately set according to the target surface modification. The plasma treatment time, electric power, frequency, conductor temperature, irradiation direction, etc. can be appropriately selected to perform the target surface modification.

[0085] The CO2 plasma treatment is preferably performed before or after the conductor preheating (preheating) for forming the resin coating layer (before the conductor preheating or after the conductor preheating), or before or after the conductor preheating. In the present invention or this specification, the above-mentioned "conductor preheating" means that the conductor surface is preheated in advance when the resin is extruded and coated on the conductor. The conductor preheating can be performed, for example, by an induction heating furnace. There is no particular restriction on the heating temperature. For example, the conductor temperature just before extrusion can be set to 200 to 600°C, more preferably set to 300 to 500°C, and further preferably set to 350 to 450°C. It should be noted that since the aluminum conductor will also be heated by CO2 plasma treatment, if the time of the plasma treatment process is extended, it can also replace the conductor preheating process. Such a method is also included in the method of preheating the conductor.

[0086] (Formation of Resin Coating Layer)

[0087] The insulated wire of the present invention can be obtained by using an aluminum conductor treated with CO2 plasma as a core wire, and extruding and coating a composition containing the above-mentioned specific thermoplastic resin using a screw of an extruder to form a resin coating layer. The extrusion coating method itself can be carried out by a conventional method. The head temperature of the extrusion coating can be appropriately set in consideration of the adhesion between the conductor and the resin coating layer. For example, the head temperature is preferably 350°C or more, more preferably 400°C or more, and further preferably 450°C or more.

[0088] When an amorphous thermoplastic resin is used, in addition to extrusion coating, a varnish dissolved in an organic solvent or the like may be applied to the enameled wire using a die having a shape similar to that of the conductor and then baked.

[0089] [Coils, rotating electrical machines, and electrical / electronic equipment]

[0090] The insulated wire of the present invention can be used as a coil in fields requiring electrical properties (voltage resistance) and heat resistance, such as rotating electric machines and various electrical / electronic equipment. For example, the insulated wire of the present invention is used in motors, transformers, etc., and can constitute high-performance rotating electric machines and electrical / electronic equipment. It is particularly suitable for use as a winding for a drive motor of a hybrid vehicle (HV) or an electric vehicle (EV).

[0091] Examples of the coil of the present invention include a coil formed by subjecting the insulated wire of the present invention to coil processing, and a coil formed by subjecting the insulated wire of the present invention to bending processing and then electrically connecting predetermined portions.

[0092] The coil formed by coiling the insulated wire of the present invention is not particularly limited, and a coil formed by winding a long insulated wire into a spiral shape can be cited. In such a coil, the number of windings of the insulated wire is not particularly limited. Usually, an iron core is used when winding the insulated wire.

[0093] Examples of the coil formed by bending the insulated wire of the present invention and electrically connecting specific portions thereof include coils used in stators of rotating motors and the like. Examples of such coils include: Figure 2 As shown, the insulated wire of the present invention is cut into a predetermined length and bent into a U-shape to produce two or more wire segments 34, and the two open ends (terminal ends) 34a of the U-shape of each wire segment 34 are connected alternately to produce a coil 33 (see Figure 2 , Figure 3 ).

[0094] There is no particular limitation on the electrical / electronic device using the coil. A preferred embodiment of such an electrical / electronic device is a transformer. Figure 2 , Figure 3 The stator 30 shown is a rotating electric machine (particularly a driving electric machine for HVs and EVs). The rotating electric machine may have the same configuration as a conventional rotating electric machine except that the stator 30 is provided.

[0095] The stator 30 may be similar to a conventional stator except that the wire segment 34 is formed of the insulated wire of the present invention. That is, the stator 30 includes a stator core 31 and a coil 33, wherein the coil 33 is, for example, Figure 2 As shown in FIG. 1 , the wire segment 34 made of the insulated wire of the present invention is assembled into the slot 32 of the stator core 31, and the open end 34a is electrically connected. The coil 33 is in a state where the adjacent fusion layers are fixed to each other or the fusion layer and the slot 32 are fixed. Here, the wire segment 34 can be inserted into the slot 32 alone, but it is preferably as follows. Figure 2The stator 30 houses the coil 33 formed by interlacing and connecting the two ends, that is, the open ends 34a of the wire segments 34 bent as described above, in the slots 32 of the stator core 31. At this time, the open ends 34a of the wire segments 34 may be connected and then housed in the slots 32, or the open ends 34a of the wire segments 34 may be bent and connected after the wire segments 34 are housed in the slots 32.

[0096] Example

[0097] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these embodiments.

[0098] <Manufacturing method>

[0099] [Example 1]

[0100] An insulated electric wire including an aluminum conductor and an insulating coating (resin coating layer) was produced by the following method.

[0101] As an aluminum conductor, a square conductor (made of aluminum with a purity of 99.50%; A1050) with a square cross section (long side 3.5 mm × short side 2.0 mm, radius of curvature of the chamfered corners r = 0.3 mm) was used. The aluminum conductor was preheated in an induction heating furnace so that the conductor temperature immediately before extrusion reached 400°C, and CO2 plasma irradiation was performed under the conditions of CO2 gas concentration of 99 Vol%, output power of 500 W, and irradiation time of 0.5 seconds. The surface roughness (arithmetic mean roughness [Sa]; ISO standard) of the aluminum conductor after plasma treatment was measured using a laser microscope VK-X250 (magnification: 400 times) manufactured by Keyence according to surface roughness measurement (ISO 25178 surface properties).

[0102] The aluminum conductor treated with CO2 plasma was used as the core wire, and an extruder with a 30 mm full-length screw (screw L / D = 25, screw compression ratio = 3) was used as the screw. Polyetheretherketone (PEEK) resin was extruded and coated on the core wire using an extrusion die in such a way that the cross-sectional shape of the insulating film was similar to the shape of the conductor. In this way, an insulated wire of Example 1 having an insulating film made of PEEK resin with a thickness of 100 μm formed on the outer periphery of the conductor was obtained. It should be noted that as a comparison object for the following adhesion strength test, an aluminum conductor not treated with plasma was used, and the insulated wire as a comparison object was obtained in the same manner as Example 1 except that the aluminum conductor not treated with plasma was used.

[0103] [Examples 2 to 12]

[0104] The insulated wires of Examples 2 to 12 shown in the following table were prepared in the same manner as described above except that the type (material) of the aluminum conductor and the type of the resin constituting the insulating coating were the types described in Table 1 below. The detailed information of the conductor and the resin is as follows. In addition, as a comparison object for the following adhesion strength test, each insulated wire as a comparison object was obtained in the same manner as Examples 2 to 12 except that a conductor not treated with plasma was used.

[0105] -conductor-

[0106] A1070: 99.70% pure aluminum

[0107] A1080: 99.80% pure aluminum

[0108] ·MSAL: Al-0.2Fe-0.2Cu-0.1Mg

[0109] ·Al-Fe:Al-0.6Fe

[0110] ·A6101: Al-Mg-Si system

[0111] -Resin-

[0112] PEKK: OXPEKK-IG100 (trade name), manufactured by Oxford Performance Materials

[0113] ·PPS: FZ-2100 (trade name), manufactured by DIC Corporation

[0114] PEK: HT-G22 (trade name), manufactured by Victrex

[0115] [Comparative Example 1]

[0116] The insulated wire of Comparative Example 1 shown in the following table was obtained in the same manner as above except that an aluminum conductor not treated with plasma was used to produce the insulated wire. It should be noted that in Comparative Example 1, no plasma treatment was performed, so the surface roughness of the conductor described in Table 1 is the original surface roughness of the conductor used.

[0117] [Comparative Examples 2 to 6]

[0118] Insulated wires of Comparative Examples 2 to 6 shown in the following table were obtained in the same manner as described above except that different plasma treatments were performed instead of CO2 plasma. In addition, as a comparison object for the following adhesion strength test, each insulated wire as a comparison object was obtained in the same manner as Comparative Examples 2 to 6 except that a conductor not treated with plasma was used. It should be noted that the irradiation conditions of each plasma were an output power of 500 W and an irradiation time of 0.5 seconds.

[0119] [Comparative Example 7]

[0120] As an aluminum conductor, a square conductor (made of aluminum with a purity of 99.70; A1070) with a square cross section (long side 3.5 mm×short side 2.0 mm, four corners with a radius of curvature r=0.3 mm) was used. The aluminum conductor was subjected to a pulse energy of 1 mJ and a processing density of 500 points / mm. 2 It should be noted that the surface roughness (arithmetic mean roughness [Sa]) of the conductor after laser treatment was measured using a laser microscope VK-X250 (magnification: 400 times) manufactured by Keyence Corporation according to surface roughness measurement (ISO 25178 surface properties).

[0121] The insulating coating shown in the following table was formed in the same manner as above except that the obtained laser-treated aluminum conductor was used, thereby obtaining an insulated wire of Comparative Example 7. In addition, an insulated wire as a comparative object was obtained in the same manner as Comparative Example 7 except that an untreated conductor was irradiated with laser as a comparative object in the following adhesion strength test.

[0122] [Reference Example 1]

[0123] Insulated wires of Reference Example 1 shown in the following table were prepared in the same manner as above except that polyetherimide (PEI) resin was used instead of PEEK resin. Insulated wires were obtained in the same manner as Reference Example 1 except that a conductor not treated with plasma was used as a comparison object for the following adhesion strength test.

[0124] The adhesion strength, dielectric breakdown voltage and heat resistance of each of the insulated wires produced above were evaluated as follows. The obtained results are summarized in Table 1 below.

[0125] <Evaluation method>

[0126] [Measurement of Adhesion Strength]

[0127] The adhesion strength between the aluminum conductor and the insulating film was measured according to Japanese Industrial Standard: JIS Z 0237 2009 by the following method.

[0128] For the insulated wires of the above-mentioned embodiments and comparative examples (insulated wires for comparison made using aluminum conductors with untreated surfaces (before surface treatment), and insulated wires made using aluminum conductors after surface treatment (plasma treatment or laser treatment)), parallel cuts of 1 mm width and more than 50 mm are cut in the length direction. The cuts reach the conductor. Use a tensile testing machine (manufactured by Shimadzu Corporation, device name "Autograph AGSJ") to peel off the entire insulating film located between the cuts from the conductor, measure the force applied during the peeling (180° peel strength, peeling speed 4 mm / min), and take the maximum peel strength as the adhesion strength (adhesion force). The results are shown in Table 1.

[0129] In addition, the change rate of the adhesion strength due to the surface treatment was calculated and numerically expressed by the calculation formula [(adhesion strength between the conductor and the insulation coating after surface treatment) / (adhesion strength between the conductor and the insulation coating before surface treatment)] (represented as [after / before] in Table 1). The results are shown in Table 1.

[0130] [Dielectric breakdown voltage]

[0131] An aluminum foil with a width of about 20 mm is wrapped around the center of each insulated wire cut into a 50 cm long sample (straight test piece), and an electrode is set on the aluminum foil. In addition, an electrode is set on the conductor exposed by peeling off the insulating coating between one end of the insulated wire and a distance of 5 mm. A sinusoidal 50 Hz AC voltage is applied between these electrodes at a boost rate of 500 V / sec, and the voltage (effective value) when insulation breakdown occurs is measured as the insulation breakdown voltage. The temperature of the measurement environment is room temperature (about 23°C). The results are shown in Table 1.

[0132] [Evaluation of adhesion strength after heat treatment]

[0133] Each of the above insulated wires produced using the surface treated aluminum conductor was cut into 300 mm lengths and heat treated in air at 220° C. for 100 hours. The adhesion strength of each heat treated insulated wire was measured in the same manner as above. The results are shown in Table 1.

[0134]

[0135] The insulated wire of Comparative Example 1 did not perform surface treatment on the aluminum conductor, and as a result, the insulation coating composed of PEEK resin had poor adhesion to the aluminum conductor. In addition, in the case of the insulated wires of Comparative Examples 2 to 6, which were plasma-treated using various plasmas instead of CO2 plasma, the adhesion between the aluminum conductor and the insulation coating composed of PEEK resin after plasma irradiation was poor. In all comparative examples, the adhesion strength was less than 0.5 N / m, and the rate of change of the adhesion strength based on plasma irradiation was less than 5 times. In addition, by performing heat treatment on the insulated wire, it was observed that the adhesion strength was further reduced.

[0136] In Comparative Example 7, in which the surface of the aluminum conductor was roughened by laser treatment instead of plasma treatment, the adhesion between the aluminum conductor and the insulating film made of PEEK resin was improved by roughening, but the dielectric breakdown voltage was less than 100 kV / mm. This is considered to be because aluminum particles caused by laser roughening were mixed into the insulating film, thereby reducing the dielectric breakdown voltage.

[0137] Furthermore, in the insulated wire of Reference Example 1 manufactured using PEI resin, the adhesion between the aluminum conductor and the insulating film composed of PEI resin was high even without CO2 plasma treatment, and on the contrary, the adhesion was not greatly changed even when the aluminum conductor was subjected to CO2 plasma treatment. It can be seen that the effect of CO2 plasma treatment of the aluminum conductor is significant when PAEK resin or PPS resin is used as the insulating film in contact with the conductor.

[0138] In contrast, in the insulated wires of Examples 1 to 12 satisfying the constitution of the present invention, the aluminum conductors were subjected to CO2 plasma treatment, and thus the conductors had excellent adhesion to the insulating coating made of any one of PEEK, PEKK, PPS, and PEK, and the adhesion strength was 1 N / mm or more. In addition, it was shown that the adhesion strength with the insulating coating increased by more than 17 times by CO2 plasma treatment. In addition, it was shown that all the insulated wires showed high dielectric breakdown voltage and had excellent adhesion even after heat treatment.

[0139] The present invention has been described in conjunction with its embodiments, but the applicant believes that, unless otherwise specified, the present invention is not limited to any details in the description and should be broadly interpreted without violating the spirit and scope of the invention as shown in the appended claims.

[0140] This application claims the priority based on Japanese Patent Application No. 2022-129364 filed in Japan on August 15, 2022, the contents of which are hereby incorporated by reference as a part of the contents described in this specification.

[0141] Explanation of symbols

[0142] 1 Insulated wire

[0143] 11 Conductor

[0144] 12 Resin coating

[0145] 30 Stator

[0146] 31 stator core

[0147] 32 slots

[0148] 33 Coil

[0149] 34 Wire Segment

[0150] 34a Open end

Claims

1. An insulated wire comprising a conductor and a resin coating layer covering the periphery of the conductor, wherein: The conductor is an aluminum conductor that has been surface treated with CO2 plasma. At least a portion of the resin coating layer in contact with the conductor includes at least one of a polyaryletherketone resin and a polyphenylene sulfide resin.

2. The insulated wire according to claim 1, wherein The polyaryletherketone resin includes at least one of a polyetheretherketone resin, a polyetherketoneketone resin, and a polyetherketone resin.

3. The insulated wire according to claim 1 or 2, wherein: The conductor has a surface with an arithmetic mean roughness Sa of 3 μm or less.

4. The insulated wire according to any one of claims 1 to 3, wherein The resin coating layer has an adhesion strength of 1.0 N / mm or more to the conductor.

5. The insulated wire according to any one of claims 1 to 4, wherein After the insulated wire is heat treated at 220° C. for 100 hours, the adhesion strength of the resin coating layer to the conductor is 1.0 N / mm or more. 6 . A coil using the insulated wire according to claim 1 .

7. A rotating electrical machine or an electrical or electronic device comprising the coil according to claim 6.

8. A method for producing an insulated wire, which is the method for producing an insulated wire according to any one of claims 1 to 5, comprising the following steps: A resin coating layer containing at least one of a polyaryletherketone resin and a polyphenylene sulfide resin is formed at least in a portion in contact with the aluminum conductor by extruding a coating resin onto the aluminum conductor surface treated by CO 2 plasma.

9. The method for producing an insulated wire according to claim 8, wherein: The conductor was surface treated by CO2 plasma after preheating.

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