Flat wire and method for manufacturing same

Abstract

A flat wire comprising a flat copper conductor having a rectangular cross-section in a direction perpendicular to the axial direction, and an insulating coating material film directly covering the entire flat copper conductor in the circumferential direction, wherein the cross-sectional area of the flat copper conductor is 2.0 mm2 or more, the average thickness of the film of the insulating coating material is 30 to 500 μm, the insulating coating material contains a fluorine-containing polymer, and the material fracture strength is higher than the interfacial strength of the film comprising the insulating coating material.

Description

Rectangular wire and method for manufacturing the same 【0001】 This invention relates to a rectangular wire and a method for manufacturing the same. This application claims priority based on Japanese Patent Application No. 2024-214603, filed in Japan on December 9, 2024, the contents of which are incorporated herein by reference. 【0002】 Vehicle equipment used in automobiles, railways, aircraft, etc., is expected to be smaller and lighter. Therefore, the insulating coatings on the insulated wires of electrical equipment used in the above-mentioned vehicle equipment need to be thinner. Furthermore, with the increasing power output and voltage of electrical equipment, the insulating coatings need to have not only excellent insulating properties but also strong adhesion to conductors. 【0003】 By using flat rectangular conductors for electric wires, the space utilization ratio when coiled is higher compared to round wires. As a result, the overall space required for the coil can be reduced, contributing to the miniaturization of electrical equipment. However, with flat rectangular conductors, it is more difficult to form a uniform insulating coating compared to round wires, which can lead to problems in maintaining sufficient insulation. 【0004】 Patent Document 1 discloses an insulated wire comprising a conductor heated using a halogen heater and a fluororesin layer formed on the conductor and containing a melt-workable fluororesin, wherein the peel strength measured by peeling the fluororesin layer from the conductor is 0.30 N / mm or more, and the content of other components in the fluororesin layer relative to the mass of the fluororesin in the fluororesin layer is less than 30% by mass. It is also stated that the adhesion between the conductor and the fluororesin layer covering the conductor has been improved in the insulated wire. 【0005】 Patent No. 7510096 【0006】 However, even in the insulated wire described in Patent Document 1, the adhesion between the conductor and the fluororesin layer covering the conductor is not sufficient. The object of the present invention is to provide a flat wire with high adhesion between the flat copper conductor and the insulating coating, and a method for manufacturing the same. 【0007】The present invention has the following aspects: [1] A rectangular wire comprising a rectangular copper conductor having a rectangular cross-section in a direction perpendicular to the axial direction, and a coating of insulating material that directly covers the entire circumferential direction of the rectangular copper conductor, wherein the cross-sectional area of ​​the rectangular copper conductor is 2.0 mm². ２ [1] A flat wire having the above characteristics, wherein the average thickness of the film of the insulating coating material is 30 to 500 μm, the insulating coating material contains a fluorine-containing polymer, and the interfacial strength between the flat copper conductor and the film of the insulating coating material is higher than the material fracture strength of the insulating coating material. [2] The flat wire according to [1], wherein the oxygen atom content on the surface of the flat copper conductor is 1.0% by mass or more. [3] The flat wire according to [1] or [2], wherein the material fracture strength of the insulating coating material is 0.30 to 3.40 kgf. [4] The flat wire according to any one of [1] to [3], wherein the fluorine-containing polymer is a fluorine-containing resin with a melting point of 160°C or higher. [5] The flat wire according to [4], wherein the fluorine-containing resin has units based on tetrafluoroethylene. [6] The flat wire according to any one of [1] to [3], wherein the fluorine-containing polymer is a fluorine-containing elastomer. [7] The flat wire according to [6], wherein the fluorine-containing elastomer has units based on tetrafluoroethylene. [8] The flat wire according to any one of [1] to [7], wherein the film of the insulating coating material is a film of insulating coating material formed by extrusion molding. [9] The flat wire according to any one of [1] to [8], wherein the insulating coating material further comprises a non-fluorine thermoplastic resin.

[10] The flat wire according to [9], wherein the non-fluorine thermoplastic resin comprises one or more selected from the group consisting of polyarylether ketone and polyphenylene sulfide. 【0008】

[11] A method for manufacturing a rectangular wire according to any one of [1] to

[10] , comprising: melting a composition containing the fluorine-containing polymer using an extruder equipped with a die; and extruding the molten composition from the die around the rectangular copper conductor to coat the rectangular copper conductor with the molten composition and form the insulating coating material, wherein the drawdown ratio DDR calculated by the following formula 1 is less than 15. DDR = (D Ａ -C Ａ ) / (F Ａ -C Ａ) In Formula 1, D Ａ is the opening area of the die (mm ２ ), C Ａ is the cross-sectional area (mm ２ ) of the cross-section perpendicular to the axial direction of the flat copper conductor, and F Ａ is the cross-sectional area (mm ２ ) of the cross-section perpendicular to the axial direction of the flat wire.

[12] The method for manufacturing a flat wire according to

[11] , wherein the flat copper conductor is a flat copper conductor preheated at 160° C. or higher in an oxygen-containing gas atmosphere.

[13] The method for manufacturing a flat wire according to claim 12, wherein the preheating means of the flat copper conductor is a method of generating a magnetic field and heating by the internal resistance of the metal.

[14] The flat wire according to any one of [1] to

[10] , wherein the tensile breaking strength of the insulating coating material is 33 to 47 MPa and the material breaking strength of the insulating coating material is 1.00 to 1.45 kgf. 【0009】 According to the present invention, it is possible to provide a flat wire having high adhesion between a flat copper conductor and a film of an insulating coating material, and a method for manufacturing the same. 【0010】The surface element content of the rectangular copper conductor can be measured by scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX). The melt flow rate is the melt mass flow rate specified in JIS K 7210-1:2014 (corresponding international standard ISO 1133-1:2011). Hereinafter, the melt flow rate will also be referred to as MFR. The melt viscosity can be determined by the method described in the examples. The average thickness of the insulating coating is obtained by taking a 5m length of rectangular wire, measuring the thickness of the insulating coating on the long side of a rectangular cross-section perpendicular to the axial direction every 100mm, and taking the arithmetic mean. The unbiased standard deviation of the thickness of the insulating coating in the axial direction of the rectangular wire is obtained by taking a 5m length of rectangular wire, measuring the thickness of the insulating coating on the long side of a rectangular cross-section perpendicular to the axial direction every 100mm, and taking the measured values. The iodine atom content in the fluorine-containing elastomer (A2) can be determined by ion chromatography. The melting point can be determined as the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC). The storage modulus G' of the fluorine-containing elastomer (A2) is the value measured under conditions of 100°C and 50 cpm in accordance with ASTM D6204. The Mooney viscosity (ML) of the fluorine-containing elastomer (A2) １＋１０ The value (at 121°C) is measured at 121°C in accordance with JIS K6300-1:2000 (corresponding international standards ISO 289-1:2005, ISO 289-2:1994). The tensile breaking strength of the insulating coating material can be measured in accordance with ASTM D 638. The unit of tensile breaking strength is MPa or kgf / mm ２ Therefore, 1 MPa is equal to 0.101972 kgf / mm². ２ The material fracture strength of the insulating coating is obtained by multiplying the tensile fracture strength of the insulating coating by the width of the rectangular copper conductor and the average thickness of the coating. The unit of material fracture strength is kgf. 【0011】A polymer unit refers to a part (polymerization unit) derived from a monomer, formed by the polymerization of monomers. The unit may be a unit directly formed by a polymerization reaction, or it may be a unit in which a part of the polymer is converted to a different structure by processing the polymer. In this specification, a monomer-based unit is also called a monomer unit. 【0012】 ≪Flat Rectangular Wire≫ The flat rectangular wire of this embodiment comprises a flat rectangular copper conductor having a rectangular cross-section in a direction perpendicular to the axial direction, and a coating of insulating material that directly covers the entire circumferential direction of the flat rectangular copper conductor. The cross-sectional area of ​​the flat rectangular copper conductor is 2.0 mm². ２ The above is the result. The average thickness of the insulating coating is 30 to 500 μm. The insulating coating contains a fluorine-containing polymer. The interfacial strength between the flat copper conductor and the insulating coating is higher than the material fracture strength of the insulating coating. The fact that the interfacial strength between the flat copper conductor and the insulating coating is higher than the material fracture strength of the insulating coating can be confirmed by the measurement method of the example described below. Specifically, the insulating coating is cut circumferentially with a cutter, the cut surface is grasped, 1 mm of the coating is peeled off with tweezers in a 180° direction to form the gripping portion, and then the coating is pulled to peel the insulating coating from the flat copper conductor. In this case, if the insulating coating breaks at a peeling distance of less than 2 cm, it is determined that the interfacial strength > material fracture strength. On the other hand, if it does not break, it is determined that the interfacial strength ≤ material fracture strength. If the interfacial strength between the rectangular copper conductor and the insulating coating is higher than the material fracture strength of the insulating coating, the adhesion between the rectangular copper conductor and the insulating coating will improve. 【0013】 <Flat Rectangular Copper Conductor> A flat rectangular copper conductor is the core wire of a flat wire, and is a conductor with a rectangular cross-section perpendicular to the axial direction. The material of the flat rectangular copper conductor is copper. The thickness of the flat rectangular copper conductor is, for example, 0.5 mm to 3.0 mm. The width of the flat rectangular copper conductor is, for example, 1.0 mm to 5.0 mm. The thickness of the flat rectangular copper conductor is the shorter side of the rectangular cross-section perpendicular to the axial direction. The width of the flat rectangular copper conductor is the longer side of the rectangular cross-section perpendicular to the axial direction. 【0014】 The cross-sectional area of ​​the flat copper conductor is 2.0 mm². ２ That's all, 3.0 mm ２ The above is more preferable, 3.3 mm ２The above is even more preferable. There is no particular upper limit to the cross-sectional area of ​​the rectangular copper conductor, but for example, 15 mm ２ The cross-sectional area of ​​the rectangular copper conductor is 2.0 to 15 mm². ２ Preferably, 3.0 to 15 mm ２ More preferably, 3.3 to 15 mm ２ This is even more preferable. The cross-sectional area of ​​the rectangular copper conductor is the area of ​​the cross-section in the direction perpendicular to the axial direction. If the conformability of the insulating coating to the rectangular copper conductor during bending deformation is low, the larger the cross-sectional area of ​​the rectangular copper conductor, the more likely it is that wrinkles will form in the insulating coating or the insulating coating will peel off from the rectangular copper conductor during bending deformation of the rectangular wire. Since the rectangular wire of this embodiment has excellent conformability of the insulating coating to the rectangular copper conductor during bending deformation, the larger the cross-sectional area of ​​the rectangular copper conductor, the more useful it is. 【0015】 The oxygen atom content on the surface of the rectangular copper conductor is preferably 1.0% by mass or more, more preferably 1.4% by mass or more, and even more preferably 1.8% by mass or more. The oxygen atom content on the surface of the rectangular copper conductor is preferably 20% by mass or less, more preferably 5% by mass or less, and even more preferably 2.5% by mass or less. When the oxygen atom content on the surface of the rectangular copper conductor is above the lower limit, the adhesion of the coating to the conductor is excellent. When the oxygen atom content on the surface of the rectangular copper conductor is below the upper limit, the strength of the rectangular copper conductor is excellent. 【0016】 <Insulating Coating> The average thickness of the insulating coating is 30 to 500 μm, preferably 50 to 300 μm, and more preferably 70 to 200 μm. If the average thickness of the coating is above the lower limit, tracking resistance is excellent. If the average thickness of the coating is below the upper limit, the overall thickness of the flat wire can be reduced, which allows for space saving of the entire coil when it is made into a coil, contributing to the miniaturization of electrical equipment. 【0017】The unbiased standard deviation of the thickness of the insulating coating film in the axial direction of the rectangular wire (hereinafter also simply referred to as "thickness variation") is preferably less than 0.06 mm, more preferably 0.03 mm or less, and even more preferably 0.01 mm or less. When the thickness variation of the film is less than (or less than) the above upper limit, the crack resistance and tracking resistance during bending deformation are excellent. The smaller the thickness variation of the film, the better, and it may even be 0. From the viewpoint of ease of manufacture and yield, the thickness variation of the film is preferably 0.001 mm or more. The above lower limit and upper limit can be combined as appropriate. Examples of combinations include, when the thickness variation of the film is not 0, 0.001 mm or more and less than 0.06 mm, 0.001 to 0.03 mm, and 0.001 to 0.01 mm. To make the thickness variation less than 0.06 mm, it is preferable to form the insulating coating film by extrusion molding that directly covers the entire circumferential direction of the rectangular copper conductor. Other methods, such as powder coating, are undesirable because they tend to result in large variations in thickness. In particular, when forming an insulating coating with a fluororesin by powder coating, the variation tends to be larger due to the difficulty in adjusting the viscosity during melting, compared to non-fluororesins such as acrylic resin, epoxy resin, epoxy-acrylic resin, polyurethane resin, polyester resin, polyimide resin, polyamide-imide resin, and polyester-imide resin. 【0018】 The tensile breaking strength of the insulating coating material is preferably 8 to 95 MPa, more preferably 15 to 93 MPa, even more preferably 25 to 90 MPa, and particularly preferably 36 to 85 MPa. In one embodiment of this invention, the tensile breaking strength of the insulating coating material is preferably 33 to 47 MPa. If the tensile breaking strength of the insulating coating material is above the lower limit, the coating adheres well to the conductor during bending. If the tensile breaking strength of the insulating coating material is below the upper limit, the coating has excellent crack resistance during bending. 【0019】The material fracture strength of the insulating coating is preferably 0.30 to 3.40 kgf, more preferably 0.50 to 3.30 kgf, and even more preferably 0.80 to 3.20 kgf. In one embodiment of this product, the material fracture strength of the insulating coating is preferably 1.00 to 1.45 kgf. If the material fracture strength of the insulating coating is above the lower limit, the coating will have excellent adhesion to the conductor during bending. If the material fracture strength of the insulating coating is below the upper limit, the coating will have excellent crack resistance during bending. 【0020】 The MFR of the insulating coating material at a temperature of 372°C and a load of 49N is 10.0 to 300.0 g / 10 min, preferably 20.0 to 250.0 g / 10 min, and more preferably 30.0 to 200.0 g / 10 min. It is preferable to measure the MFR of the insulating coating material after preheating it to the measurement temperature (372°C) for 5 minutes. If the MFR is 100.0 g / 10 min or higher, it is preferable to shorten the preheating time. In this case, the preheating time is preferably 30 to 180 seconds. 【0021】 If the MFR of the insulating coating material at a temperature of 372°C and a load of 49N is above the lower limit, the surface smoothness of the coating and the ability of the coating to follow the flat copper conductor during bending deformation will be improved. If the MFR of the insulating coating material at a temperature of 372°C and a load of 49N is below the upper limit, the strength of the coating of the insulating coating material will be improved. 【0022】 The insulating coating material contains a fluorine-containing polymer (A). The insulating coating material may further contain other components besides the fluorine-containing polymer (A), as long as these do not significantly impair its properties. Examples of other components include a non-fluorine thermoplastic resin (B). 【0023】 <Fluorine-containing polymer (A)> The fluorine-containing polymer (A) may be a homopolymer or a copolymer. Examples of fluorine-containing polymer (A) include fluorine-containing resin (A1) and fluorine-containing elastomer (A2). Fluorine-containing elastomer (A2) is a fluorine-containing elastic polymer with no melting point, exhibiting a storage modulus G' of 80 kPa or more at 100°C and 50 cpm, and is distinguished from fluorine-containing resin (A1). 【0024】[Fluorine-containing resin (A1)] The melting point of fluoro-containing resin (A1) is preferably 160°C or higher, more preferably 200°C or higher, and even more preferably 230°C or higher. If the melting point is above the lower limit, the strength of the resulting insulating coating material is excellent. The melting point of fluoro-containing resin (A1) is preferably 350°C or lower, more preferably 340°C or lower, and even more preferably 330°C or lower. If the melting point is below the upper limit, the elongation of the resulting insulating coating material is excellent. The lower limit and upper limit can be combined as appropriate. Examples of combinations include 160-350°C, 200-340°C, and 230-330°C. 【0025】 The melt viscosity of the fluororesin (A1) is 390°C and 122 sec. －１ In the measurement conditions, 100 to 1400 Pa·s is preferred, 300 to 1300 Pa·s is more preferred, and 500 to 1200 Pa·s is even more preferred. The MFR of the fluororesin (A1) at a temperature of 372°C and a load of 49 N is preferably 10.0 to 300.0 g / 10 min, more preferably 12.0 to 200.0 g / 10 min, even more preferably 15.0 to 150.0 g / 10 min, and particularly preferably 18 to 80 g / 10 min. When the melt viscosity and MFR of the fluororesin (A1) are within the above ranges, it becomes easier to adjust the MFR of the insulating coating material to the above ranges. 【0026】 The fluororesin (A1) preferably has units based on tetrafluoroethylene (hereinafter also referred to as "TFE"). It is even more preferable that the fluororesin (A1) has TFE units and other units other than TFE units. 【0027】 Other units include u1, which is based on monomers containing fluorine other than TFE units; u2, which is based on monomers containing functional groups (excluding monomers containing fluorine); and u3, which is based on monomers without fluorine (excluding monomers containing functional groups). 【0028】As monomers having fluorine unit u1, fluorine-containing compounds having one polymerizable carbon-carbon double bond are preferred. For example, fluoroolefins (e.g., vinyl fluoride, vinylidene fluoride, trifluoroethylene, hexafluoropropylene (hereinafter also referred to as "HFP"), chlorotrifluoroethylene, hexafluoroisobutylene, etc., excluding TFE), perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PAVE"), CF ２ = CFOR ｆ２ SO ２ X １ (However, R ｆ２ X is a perfluoroalkylene group having 1 to 10 carbon atoms, which may contain oxygen atoms between carbon atoms, １ (This is a halogen atom or a hydroxyl group.) CF ２ = CFOR ｆ３ CO ２ X ２ (However, R ｆ３ X is a perfluoroalkylene group having 1 to 10 carbon atoms, which may contain oxygen atoms between carbon atoms, ２ (These are hydrogen atoms or alkyl groups having 1 to 3 carbon atoms.) CF ２ = CF (CF ２ ) ｐ OCF = CF ２ Examples include (where p is 1 or 2), fluoroalkylethylenes (hereinafter also referred to as "FAE"), and fluorine-containing monomers having a ring structure (for example, perfluoro(2,2-dimethyl-1,3-dioxol), 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol, perfluoro(2-methylene-4-methyl-1,3-dioxolane), etc.). One type of fluorine-containing monomer may be used alone, or two or more types may be used in combination. 【0029】 As the monomer having unit u1 of fluorine, at least one selected from the group consisting of HFP, PAVE, and FAE is preferred from the viewpoint of excellent moldability of the composition containing the fluororesin (A1), PAVE and FAE are more preferred, and FAE is particularly preferred from the viewpoint of excellent electrical properties (dielectric constant, dielectric loss tangent) and heat resistance. 【0030】For example, PAVE is CF ２ = CFOR ｆ１ (However, R ｆ１ A perfluoroalkyl group has 1 to 10 carbon atoms and may contain oxygen atoms between carbon atoms. Specific examples of PAVE include CF ２ = CFOCF ２ CF ３ CF ２ = CFOCF ２ CF ２ CF ３ (Hereafter also referred to as "PPVE"), CF ２ = CFOCF ２ CF ２ CF ２ CF ３ CF ２ = CFO (CF ２ ) ６ F is one example. PPVE is preferred as the PAVE. 【0031】 For example, CH ２ = CX ３ (CF ２ ) ｑ X ４ (However, X ３ is a hydrogen atom or a fluorine atom, q is an integer between 2 and 10, and X ４ (These are hydrogen atoms or fluorine atoms.) Specific examples of FAE include CH ２ = CF (CF ２ ) ２ F, CH ２ = CF (CF ２ ) ３ F, CH ２ = CF (CF ２ ) ４ F, CH ２ = CF (CF ２ ) ５ F, CH ２ = CF (CF ２ ) ６ F, CH ２ = CF (CF ２ ) ２ H, CH ２ = CF (CF ２ ) ３ H, CH ２=CF(CF ２ ) ４ H, CH ２ =CF(CF ２ ) ５ H, CH ２ =CF(CF ２ ) ６ H, CH ２ =CH(CF ２ ) ２ F, CH ２ =CH(CF ２ ) ３ F, CH ２ =CH(CF ２ ) ４ F, CH ２ =CH(CF ２ ) ５ F, CH ２ =CH(CF ２ ) ６ F, CH ２ =CH(CF ２ ) ２ H, CH ２ =CH(CF ２ ) ３ H, CH ２ =CH(CF ２ ) ４ H, CH ２ =CH(CF ２ ) ５ H, CH ２ =CH(CF ２ ) ６ H is included. As the FAE, CH ２ =CH(CF ２ ) ｑ１ X ４ (where q1 is 2 to 6, preferably 2 to 4.) is preferred, and CH ２ =CH(CF ２ ) ２ F, CH ２ =CH(CF ２ ) ３ F, CH ２ =CH(CF ２ ) ４ F, CH ２ =CF(CF ２ ) ３ H, CH ２ =CF(CF ２ ) ４H is more preferred, CH ２ =CH(CF ２ ) ４ F, CH ２ =CH(CF ２ ) ２ F is particularly preferable. 【0032】 Examples of monomers having a functional group of unit u2 include monomers having a carboxyl group (e.g., maleic acid, itaconic acid, citraconic acid, undecylenic acid, etc.); monomers having an acid anhydride group (e.g., itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride (hereinafter also referred to as "CAH"), 5-norbornene-2,3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), maleic anhydride, etc.); monomers having a hydroxyl group and an epoxy group (e.g., hydroxybutyl vinyl ether, glycidyl vinyl ether, etc.). Monomers having a functional group may be used individually or in combination of two or more. An acid anhydride group refers to a group represented as -C(=O)-O-C(=O)-. 【0033】 As the monomer having the functional group of unit u2, a monomer having an acid anhydride group is preferred, and one or more selected from the group consisting of IAH, CAH, and NAH is preferred, IAH and NAH are more preferred, and NAH is even more preferred. By using one or more selected from the group consisting of IAH, CAH, and NAH, a fluororesin (A1) having an acid anhydride group can be easily produced without using the special polymerization method required when maleic anhydride is used (see Japanese Patent Publication No. 11-193312). 【0034】 Preferred monomers that do not contain fluorine in unit u3 are fluorine-free compounds having one polymerizable carbon-carbon double bond, such as olefins (e.g., ethylene (hereinafter also referred to as "E"), propylene, 1-butene, etc.) and vinyl esters (e.g., vinyl acetate, etc.). One type of fluorine-free monomer may be used alone, or two or more types may be used in combination. 【0035】The fluororesin (A1) preferably has at least one functional group selected from the group consisting of carbonyl group-containing groups, hydroxyl groups, epoxy groups, and isocyanate groups. The presence of a functional group in the fluororesin (A1) makes it easier to disperse in the non-fluorothermoplastic resin (B) when the insulating coating material contains a non-fluoroplastic resin (B). Furthermore, the functional group bonds with atoms (especially oxygen atoms) on the surface of the flat copper conductor, improving the adhesion of the insulating coating material to the flat copper conductor. The functional group is preferably present in either the terminal groups of the main chain or the pendant groups of the main chain of the fluororesin (A1), or both. The main chain refers to the main carbon chain of a chain-like compound, meaning the trunk portion with the largest number of carbon atoms. 【0036】 As for functional groups, when the insulating coating material contains a non-fluorine thermoplastic resin (B), carbonyl group-containing groups are preferred from the viewpoint of dispersibility in the non-fluorine thermoplastic resin (B). A carbonyl group-containing group is a group having a carbonyl group -C(=O)- in its structure. Examples of carbonyl group-containing groups include groups having a carbonyl group between the carbon atoms of a hydrocarbon group, carbonate groups, carboxyl groups, haloformyl groups, alkoxycarbonyl groups, and acid anhydride groups. Examples of hydrocarbon groups in groups having a carbonyl group between the carbon atoms of a hydrocarbon group include alkylene groups having 2 to 8 carbon atoms. The number of carbon atoms in the alkylene group is the number of carbon atoms excluding those constituting the carbonyl group. The alkylene group may be linear or branched. A haloformyl group is represented as -C(=O)-X (where X is a halogen atom). Examples of halogen atoms in a haloformyl group include fluorine atoms and chlorine atoms, with fluorine atoms being preferred. In other words, a fluoroformyl group (also called a carbonyl fluoride group) is preferred as the haloformyl group. As for the alkoxy group in the alkoxycarbonyl group, an alkoxy group having 1 to 8 carbon atoms is preferred, and a methoxy group or an ethoxy group is particularly preferred. The alkoxy group may be linear or branched. 【0037】Examples of functional group-containing fluororesins (A1) include the following, depending on the manufacturing method: Fluorine-containing resin (A1-1): A fluororesin having a functional group derived from at least one selected from the group consisting of monomers, chain transfer agents, and polymerization initiators used in the production of the fluororesin. Fluorine-containing resin (A1-2): A fluororesin in which a functional group is introduced into a fluororesin without a functional group by surface treatment such as corona discharge treatment or plasma treatment. Fluorine-containing resin (A1-3): A fluororesin in which a monomer having a functional group is graft polymerized into a fluororesin without a functional group. Among these, fluororesin (A1-1) is preferred as the functional group-containing fluororesin. 【0038】 If the functional groups in the fluororesin (A1-1) originate from the monomer used in the production of the fluororesin (A1-1), then the monomer may be one having the above-mentioned u2 functional group. 【0039】 If the functional groups in the fluororesin (A1-1) originate from the chain transfer agent used in the production of the fluororesin (A1-1), then a chain transfer agent having functional groups such as acetic acid, acetic anhydride, methyl acetate, ethylene glycol, or propylene glycol may be used. In this case, the functional groups exist as terminal groups in the main chain of the fluororesin (A1-1). 【0040】 If the functional groups in the fluororesin (A1-1) originate from the polymerization initiator used in the production of the fluororesin (A1-1), then a polymerization initiator having functional groups such as di-n-propyl peroxydicarbonate, diisopropyl peroxycarbonate, tert-butylperoxyisopropyl carbonate, bis(4-tert-butylcyclohexyl)peroxydicarbonate, or di-2-ethylhexyl peroxydicarbonate may be used as the polymerization initiator. In this case, the functional groups exist as terminal groups of the main chain of the fluororesin (A1-1). 【0041】 The functional groups in the fluororesin (A1-1) may be derived from two or more of the monomers, chain transfer agents, and polymerization initiators used in the production of the fluororesin (A1-1). 【0042】 As for the fluororesin (A1-1), it is preferable to have functional groups derived from the monomer used in the production of the fluororesin (A1-1) because the content of functional groups can be easily controlled. As for the fluororesin (A1-1) having functional groups derived from monomers, from the viewpoint of thermal stability, a fluoropolymer having TFE, a unit u2 based on a cyclic hydrocarbon monomer having an acid anhydride group (hereinafter also referred to as "acid anhydride group-containing cyclic hydrocarbon monomer"), and a unit u1 based on a monomer having fluorine other than the TFE unit is preferred. The acid anhydride group of unit u2 corresponds to the functional group. 【0043】 The functional group content in the fluororesin (A1) is equal to the carbon number of the main chain of the fluororesin (A1) (1 × 10⁶). ６ The functional group content is preferably 10 to 60,000 units, more preferably 100 to 50,000 units, even more preferably 100 to 10,000 units, and particularly preferably 300 to 5,000 units per unit. When the functional group content is above the lower limit, the dispersibility is excellent, and when it is below the upper limit, the thermal stability is excellent. The functional group content can be measured by methods such as nuclear magnetic resonance (NMR) analysis and infrared absorption spectroscopy. For example, as described in Japanese Patent Application Publication No. 2007-314720, the proportion (mol%) of units having functional groups in the total units constituting the fluororesin (A1) can be determined using methods such as infrared absorption spectroscopy, and the functional group content can be calculated from this proportion. 【0044】 The preferred content and ratio of each unit in the fluororesin (A1) are as follows. When the fluororesin (A1) does not contain unit u3, the content of TFE units relative to the total amount of constituent units of the fluororesin (A1) is preferably 90.0 to 99.9 mol%, more preferably 95.0 to 99.5 mol%, and even more preferably 96.0 to 99.0 mol%. When the fluororesin (A1) contains unit u3, the content of TFE units relative to the total amount of constituent units of the fluororesin (A1) is preferably 30.0 to 70.0 mol%, more preferably 35.0 to 65.0 mol%, and even more preferably 40.0 to 60.0 mol%. 【0045】When the fluororesin (A1) contains unit u1, the content of unit u1 relative to the total amount of constituent units of the fluororesin (A1) is preferably 0.1 to 10.0 mol%, and more preferably 0.5 to 5.0 mol%. 【0046】 When the fluororesin (A1) contains unit u2, the content of unit u2 relative to the total amount of constituent units of the fluororesin (A1) is preferably 0.01 to 1.0 mol%, and more preferably 0.05 to 0.5 mol%. 【0047】 When the fluororesin (A1) contains unit u3, the content of unit u3 relative to the total amount of constituent units of the fluororesin (A1) is preferably 20.0 to 60.0 mol%, more preferably 25.0 to 55.0 mol%, and even more preferably 30.0 to 50.0 mol%. In one embodiment, it is preferable that the fluororesin (A1) does not contain unit u3. 【0048】 The total content of TFE units and units u1 to u3 relative to the total amount of constituent units of the fluororesin (A1) is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 100 mol%. 【0049】 When the content of each unit is within the above range, the surface smoothness of the insulating coating and the conformability of the insulating coating to the rectangular copper conductor during bending deformation are improved in the resulting rectangular wire. 【0050】 The proportion of each unit can be calculated by melt NMR analysis, fluorine content analysis, infrared absorption spectroscopy, etc., of the fluororesin (A1). 【0051】 In fluororesins (A1), some of the acid anhydride groups in unit u2 undergo hydrolysis, and as a result, units based on dicarboxylic acids (itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, maleic acid, etc.) corresponding to acid anhydride group-containing cyclic hydrocarbon monomers may be included. When units based on the above dicarboxylic acids are included, these units shall be designated as unit u2. 【0052】Preferred specific examples of the fluororesin (A1) include TFE / PPVE copolymer, TFE / PAVE / NAH copolymer, etc., as copolymers of TFE and PAVE. Examples of TFE / HFP copolymer, TFE / HFP / PAVE copolymer, etc., as copolymers of TFE and E. ２ =CH(CF ２ ) ２ F copolymer, TFE / E / CH ２ =CH(CF ２ ) ４ F copolymer, TFE / E / CH ２ =CH(CF ２ ) ２ F / CH ２ =CH(CF ２ ) ４ F copolymer, TFE / E / HFP / IAH copolymer, TFE / E / CH ２ =CH(CF ２ ) ２ F / IAH copolymer, TFE / E / CH ２ =CH(CF ２ ) ４ F / IAH copolymer, TFE / E / CH ２ =CH(CF ２ ) ２ F / CH ２ =CH(CF ２ ) ４ Examples include F / IAH copolymers. In the case of the above copolymer, the total content of the listed units relative to the total amount of constituent units of the fluororesin (A1) is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 100 mol%. 【0053】 The fluororesin (A1) may be manufactured by a known manufacturing method or may be a commercially available product. Examples of known manufacturing methods include those described in International Publication No. 2015 / 182702, International Publication No. 2016 / 006644, and International Publication No. 2016 / 017801. 【0054】 [Fluorine-containing elastomer (A2)] The melt viscosity of fluorine-containing elastomer (A2) is 122 sec at a temperature of 300°C and a shear rate of 122 sec.－１ In the measurement conditions, 10 to 2500 Pa·s is preferred, 100 to 2300 Pa·s is more preferred, and 200 to 2000 Pa·s is even more preferred. The MFR of the fluorine-containing elastomer (A2) at a temperature of 230°C and a load of 21 N is preferably 0.1 to 300.0 g / 10 min, more preferably 1.0 to 200.0 g / 10 min, and even more preferably 40.0 to 150.0 g / 10 min. When the melt viscosity and MFR of the fluorine-containing elastomer (A2) are within the above ranges, it becomes easier to adjust the MFR of the insulating coating material to the above ranges. 【0055】 The storage modulus G' of the fluorine-containing elastomer (A2) is preferably 80 to 800 kPa, more preferably 100 to 800 kPa, and even more preferably 120 to 600 kPa. A larger storage modulus G' indicates a larger molecular weight and higher molecular chain entanglement density of the fluorine-containing elastomer (A2). When the storage modulus G' of the fluorine-containing elastomer (A2) is within the above range, the insulating coating material exhibits even greater mechanical properties such as tensile strength. 【0056】 The number average molecular weight of the fluorine-containing elastomer (A2) is preferably 10,000 to 1,500,000, more preferably 20,000 to 1,000,000, even more preferably 20,000 to 800,000, and particularly preferably 50,000 to 600,000. When the number average molecular weight of the fluorine-containing elastomer (A2) is above the lower limit of the above range, the insulating coating material exhibits excellent impact resistance and mechanical properties. When the number average molecular weight of the fluorine-containing elastomer (A2) is below the upper limit of the above range, it exhibits excellent fluidity and dispersibility in polyaryletherketone (A). As a result, flexibility is improved. The number average molecular weight is the polystyrene-equivalent molecular weight measured using GPC with tetrahydrofuran as the eluent and a calibration curve created using polystyrene polymers with known molecular weights. 【0057】 Mooney viscosity (ML) of fluorine-containing elastomer (A2) １＋１０The Mooney viscosity (ML) of the fluorine-containing elastomer (A2) is preferably 10 to 300, more preferably 20 to 280, and even more preferably 30 to 250. Mooney viscosity is a measure of molecular weight. A higher Mooney viscosity value indicates a higher molecular weight. Conversely, a lower Mooney viscosity value indicates a lower molecular weight. １＋１０ When the viscosity (121°C) is above the lower limit of the above range, the insulating coating material exhibits excellent impact resistance and mechanical properties. Mooney viscosity (ML) of fluorine-containing elastomer (A2) １＋１０ When the temperature (121°C) is below the upper limit of the above range, the fluidity and dispersibility in polyaryletherketone (A) are excellent. As a result, the composition containing fluorine-containing elastomer (A2) exhibits excellent moldability. 【0058】 The fluorine-containing elastomer (A2) preferably has TFE units. It is even more preferable that the fluorine-containing elastomer (A2) has TFE units and other units other than TFE units. 【0059】 Other units include those based on monomer m1, monomer m2, and monomer m3, as shown below. 【0060】 Monomer m1 is at least one monomer selected from the group consisting of HFP, vinylidene fluoride (hereinafter also referred to as "VdF"), and chlorotrifluoroethylene. Monomer m1 may be used alone or in combination of two or more, but it is preferable to use one monomer alone. Furthermore, monomer m1 may not be used at all. 【0061】 Monomer m2 is at least one monomer selected from the group consisting of E, propylene (hereinafter also referred to as "P"), PAVE, vinyl fluoride (hereinafter also referred to as "VF"), 1,2-difluoroethylene (hereinafter also referred to as "DiFE"), 1,1,2-trifluoroethylene (hereinafter also referred to as "TrFE"), 3,3,3-trifluoro-1-propylene (hereinafter also referred to as "TFP"), 1,3,3,3-tetrafluoropropylene, and 2,3,3,3-tetrafluoropropylene. 【0062】 PAVE includes the aforementioned PPVE and CF.２ = CFOCF ２ CF ２ CF ２ CF ３ CF ２ = CFO (CF ２ ) ６ In addition to F, CF ２ = CFOCF ３ (Hereafter also referred to as "PMVE") is one example. Among these, PMVE and PPVE are preferred as PAVE, with PMVE being more preferred. PAVE may be used alone or two or more types may be used in combination. 【0063】 Monomer m3 is a monomer that has one of the following groups at its molecular end: an iodine atom, an epoxy group, or an acid anhydride group, and is copolymerizable with TFE. By using monomer m3, one of the following groups can be introduced into the fluorine-containing elastomer (A2): an iodine atom, an epoxy group, or an acid anhydride group. The proportion of monomer m3 units is preferably 20 mol% or less, more preferably 5 mol% or less, and particularly preferably 0 mol% relative to the total units constituting the fluorine-containing elastomer (A2). 【0064】 Examples of monomers m3 having iodine atoms at their molecular ends include iodoethylene, 4-iodo-3,3,4,4-tetrafluoro-1-butene, 2-iodo-1,1,2,2-tetrafluoro-1-vinyloxyethane, 2-iodoethyl vinyl ether, allyl iodide, 1,1,2,3,3,3-hexafluoro-2-iodo-1-(perfluorovinyloxy)propane, 3,3,4,5,5,5-hexafluoro-4-iodopentene, iodotrifluoroethylene, and 2-iodoperfluoro(ethyl vinyl ether). Monomers m3 having iodine atoms at their molecular ends may be used individually or in combination of two or more. 【0065】Examples of monomers m3 having epoxy groups at the molecular termini include glycidyl esters of (meth)acrylic acid such as glycidyl (meth)acrylate and β-methylglycidyl (meth)acrylate; allyl glycidyl ethers such as allyl glycidyl ether and allyl methyl glycidyl ether; and alicyclic epoxy group-containing vinyl monomers such as 3,4-epoxycyclohexyl acrylate and 3,4-epoxycyclohexyl methacrylate. Monomers m3 having epoxy groups at the molecular termini may be used individually or in combination of two or more. 【0066】 Examples of monomers m3 having acid anhydride groups at the molecular termini include itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, and maleic anhydride. Monomers m3 having acid anhydride groups at the molecular termini may be used individually or in combination of two or more. 【0067】 Examples of fluorine-containing elastomers (A2) include the following two types of fluorine-containing copolymers: • Copolymers having TFE units and P units. • Copolymers having TFE units and PAVE units (excluding those having P units or VdF units). In these two types of fluorine-containing elastomers, the total proportion of each unit is preferably 50 mol% or more of the total units constituting the fluorine-containing elastomer (A2). 【0068】Examples of copolymers having TFE units and P units include the following: a copolymer consisting of TFE units and P units, a copolymer consisting of TFE units, P units and VF units, a copolymer consisting of TFE units, P units and VdF units, a copolymer consisting of TFE units, P units and E units, a copolymer consisting of TFE units, P units and TFP units, a copolymer consisting of TFE units, P units and PAVE units, a copolymer consisting of TFE units, P units and 1,3,3,3-tetrafluoropropene units, a copolymer consisting of TFE units, P units and 2,3,3,3-tetrafluoropropene units, a copolymer consisting of TFE units, P units and TrFE units, a copolymer consisting of TFE units, P units and DiFE units, a copolymer consisting of TFE units, P units, VdF units and TFP units, and a copolymer consisting of TFE units, P units, VdF units and PAVE units. Among copolymers having TFE units and P units, copolymers consisting of TFE units and P units are preferred. 【0069】 Examples of copolymers having TFE units and PAVE units include copolymers composed of TFE units and PAVE units. Among these, copolymers composed of TFE units and PMVE units, and copolymers composed of TFE units, PMVE units, and PPVE units are preferred, and copolymers composed of TFE units and PMVE units are more preferred. 【0070】 Other examples of fluorine-containing elastomers (A2) include copolymers comprising TFE units, VdF units, and 2,3,3,3-tetrafluoropropylene units. 【0071】 The fluorine-containing elastomer (A2) is preferably a copolymer having TFE units and P units, a copolymer having TFE units and PAVE units, more preferably a copolymer having TFE units and P units, and particularly preferably a copolymer consisting of TFE units and P units. The copolymer consisting of TFE units and P units has good thermal stability during the manufacture of rectangular wire, thus ensuring stable transportability during the manufacture of rectangular wire. In addition, discoloration and foaming of the insulating coating material are reduced. 【0072】The proportion of each unit constituting the fluorine-containing elastomer (A2) is preferably within the following ranges, given its contribution to the impact resistance of the insulating coating material. The molar ratio of each unit in a copolymer consisting of TFE units and P units (hereinafter referred to as "TFE:P", and other molar ratios are similarly referred to) is preferably 30 to 80:70 to 20, more preferably 40 to 70:60 to 30, and even more preferably 50 to 60:50 to 40. In a copolymer consisting of TFE units, P units, and VF units, TFE:P:VF is preferably 30 to 60:60 to 20:0.05 to 40. In a copolymer consisting of TFE units, P units, and VdF units, TFE:P:VdF is preferably 30 to 60:60 to 20:0.05 to 40. In copolymers consisting of TFE units, P units, and E units, the TFE:P:E ratio is preferably 20-60:70-30:0.05-40. In copolymers consisting of TFE units, P units, and TFP units, the TFE:P:TFP ratio is preferably 30-60:60-30:0.05-20. In copolymers consisting of TFE units, P units, and PAVE units, the TFE:P:PAVE ratio is preferably 40-70:60-29.95:0.05-20. In copolymers consisting of TFE units, P units, and 1,3,3,3-tetrafluoropropene units, the TFE:P:1,3,3,3-tetrafluoropropene ratio is preferably 30-60:60-20:0.05-40. In copolymers consisting of TFE units, P units, and 2,3,3,3-tetrafluoropropene units, the ratio of TFE:P:2,3,3,3-tetrafluoropropene is preferably 30-60:60-20:0.05-40. In copolymers consisting of TFE units, P units, and TrFE units, the ratio of TFE:P:TrFE is preferably 30-60:60-20:0.05-40. In copolymers consisting of TFE units, P units, and DiFE units, the ratio of TFE:P:DiFE is preferably 30-60:60-20:0.05-40. In copolymers consisting of TFE units, P units, VdF units, and TFP units, the ratio of TFE:P:VdF:TFP is preferably 30-60:60-20:0.05-40:0.05-20.In a copolymer consisting of TFE units, P units, VdF units, and PAVE units, the ratio of TFE:P:VdF:PAVE is preferably 30-70:60-20:0.05-40:0.05-20. 【0073】 In a copolymer consisting of TFE units, VdF units, and HFP units, the ratio of TFE:VdF:HFP is preferably 20 to 60:1 to 40:20 to 60. In a copolymer consisting of TFE units, VdF units, HFP units, and TFP units, the ratio of TFE:VdF:HFP:TFP is preferably 30 to 60:0.05 to 40:60 to 20:0.05 to 20. In a copolymer consisting of TFE units, VdF units, HFP units, and PAVE units, the ratio of TFE:VdF:HFP:PAVE is preferably 30 to 70:60 to 20:0.05 to 40:0.05 to 20. 【0074】 In copolymers consisting of TFE units and PAVE units, the TFE:PAVE ratio is preferably 40-70:60-30. In copolymers consisting of TFE units and PMVE units, the TFE:PMVE ratio is preferably 40-70:60-30. In copolymers consisting of TFE units, PMVE units, and PPVE units, the TFE:PMVE:PPVE ratio is preferably 40-70:3-57:3-57. 【0075】 In a copolymer consisting of TFE units, VdF units, and 2,3,3,3-tetrafluoropropylene units, the ratio of TFE:VdF:2,3,3,3-tetrafluoropropylene is preferably 1 to 30:30 to 90:5 to 60. 【0076】 Fluorine-containing elastomer (A2) may be used alone or in combination of two or more types, but it is preferable to use one type alone. Fluorine-containing elastomer (A2) may be commercially available or synthesized from various raw materials by various methods. Fluorine-containing elastomer (A2) can be synthesized, for example, by polymerizing TFE with one or more of monomers m1, m2, and m3. 【0077】During polymerization, it is preferable to use a radical polymerization initiator. Preferred radical polymerization initiators are compounds with a half-life of 10 hours at a temperature of 0 to 100°C, and particularly preferred compounds with a half-life of 20 to 90°C. Examples include azo compounds (such as azobisisobutyronitrile), non-fluorinated diacyl peroxides (such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, and lauroyl peroxide), peroxydicarbonates (such as diisopropyl peroxydicarbonate), peroxyesters (such as tert-butylperoxypivalate, tert-butylperoxyisobutyrate, and tert-butylperoxyacetate), fluorinated diacyl peroxides (compound 1 represented by formula F1 below), and inorganic peroxides (such as potassium persulfate, sodium persulfate, and ammonium persulfate). (Z(CF) ２ ) ｒ COO) ２ ...Equation F1 In the above equation F1, Z is a hydrogen atom, a fluorine atom, or a chlorine atom, and r is an integer from 1 to 10. 【0078】 Chain transfer agents may be used during polymerization. Examples of chain transfer agents include compound 2 represented by formula F2 below, compound 3 represented by formula F3 below, alcohols (methanol, ethanol, etc.), chlorofluorohydrocarbons (1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, etc.), hydrocarbons (pentane, hexane, cyclohexane, etc.), and mercaptans (tert-dodecylmercaptan, n-octadecylmercaptan, etc.). １ I ２ ...Formula F2 R ２ IBr ... Formula F3 In the above formula F2, R １ R is an alkylene group or polyfluoroalkylene group having 2 or more carbon atoms. In the above formula F3, R ２ This is an alkylene group or polyfluoroalkylene group having 1 to 16 carbon atoms. 【0079】 R １ , R ２In this, the polyfluoroalkylene group may be linear or branched. １ , R ２ As for compound 2, a perfluoroalkylene group is preferred. Examples of compound 2 include 1,4-diiodoperfluorobutane, 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane, 1,5-diiodoperfluoropentane, and 1,6-diiodoperfluorohexane. Among these, 1,4-diiodoperfluorobutane is preferred. Examples of compound 3 include 1-iodo-4-bromoperfluorobutane, 1-iodo-4-bromoperfluorobutane, 1-iodo-6-bromoperfluorohexane, and 1-iodo-8-bromoperfluoroctan. 【0080】 Iodine compounds such as Compound 2 and Compound 3 can function as chain transfer agents. Therefore, copolymerizing each monomer in the presence of an iodine compound allows iodine atoms to be bonded to the main chain ends of the fluorine-containing elastomer (A2). When obtaining a fluorine-containing elastomer (A2) with branched chains, iodine atoms can similarly be bonded to the branched chain ends. 【0081】Polymerization methods include, for example, emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization. Emulsion polymerization, which polymerizes monomers in the presence of an aqueous medium and emulsifier, is preferred because it allows for easy adjustment of the number-average molecular weight and copolymer composition of the fluorine-containing elastomer (A2) and offers excellent productivity. As radical polymerization initiators used in emulsion polymerization, water-soluble initiators are preferred. Examples of water-soluble initiators include persulfuric acid, hydrogen peroxide, water-soluble organic peroxides, organic initiators, redox initiators consisting of a combination of persulfuric acid or hydrogen peroxide and a reducing agent, and inorganic initiators in which a small amount of iron, ferrous salt, silver sulfate, etc. is further present in the presence of a redox initiator. Examples of persulfuric acid include ammonium persulfate, sodium persulfate, and potassium persulfate. Examples of water-soluble organic peroxides include disuccinate peroxide, diglutaric acid peroxide, and tert-butylhydroxyperoxide. An example of an organic initiator is azobisisobutylamidine dihydrochloride. Examples of reducing agents include sodium bisulfite and sodium thiosulfate. In emulsion polymerization, monomers are polymerized in the presence of an aqueous medium, an emulsifier, and a radical polymerization initiator to obtain elastomer latex. A pH adjusting agent may be used during monomer polymerization. 【0082】 The fluorine-containing elastomer (A2) preferably contains iodine atoms. The iodine atom content is preferably 0.05% by mass or more, more preferably 0.1 to 5% by mass, and even more preferably 0.2 to 1% by mass, based on the total mass of the fluorine-containing elastomer (A2). 【0083】 When the iodine atom content of the fluorine-containing elastomer (A2) is above the lower limit, the iodine atoms bond with atoms on the surface of the rectangular copper conductor, increasing the adhesion of the insulating coating material to the rectangular copper conductor. As a result, the conformability of the insulating coating film to the rectangular copper conductor during bending deformation is improved. 【0084】 The amount of iodine atoms can be controlled by controlling the type and amount of the chain transfer agent containing iodine atoms, the monomer containing iodine atoms, and the reaction conditions. 【0085】<Non-fluorinated thermoplastic resin (B)> Non-fluorinated thermoplastic resin (B) is a thermoplastic resin that does not contain fluorine atoms. The non-fluorinated thermoplastic resin can be any thermoplastic resin other than fluorine-containing polymer (A), and is not particularly limited. 【0086】 The melting point of the non-fluorinated thermoplastic resin (B) is preferably 200°C or higher, more preferably 250°C or higher, and even more preferably 260°C or higher. The upper limit of the melting point of the non-fluorinated thermoplastic resin (B) is not particularly limited, but for example, it is 500°C. If the melting point of the non-fluorinated thermoplastic resin (B) is above the lower limit, the heat resistance of the insulating coating material tends to improve. If the melting point of the non-fluorinated thermoplastic resin (B) is below the upper limit, it exhibits excellent moldability. 【0087】 Examples of non-fluorinated thermoplastic resins (B) include crystalline resins, amorphous resins, thermoplastic elastomers, and other thermoplastic resins. Non-fluorinated thermoplastic resins (B) may be used alone or in combination of two or more types, but it is preferable to use one type alone. 【0088】 Examples of crystalline resins include polyesters (polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, liquid crystal polyester, etc.), polyolefins (polyethylene, polypropylene, polybutylene, acid-modified polyethylene, acid-modified polypropylene, acid-modified polybutylene, etc.), polyoxymethylene, polyamides, polyarylene sulfides (polyphenylene sulfides, etc.), polyketones, polyarylether ketones, polyethernitriles, liquid crystal polymers, and the like. 【0089】 Examples of amorphous resins include styrene resins (polystyrene, acrylonitrile styrene resin, butadiene styrene resin, acrylonitrile butadiene styrene resin, etc.), polycarbonate, polymethyl methacrylate, polyvinyl chloride, unmodified or modified polyphenylene ether, thermoplastic polyimide, polyamide-imide, polyetherimide, polysulfone, polyethersulfone, polyarylate, and the like. 【0090】Examples of thermoplastic elastomers include polystyrene elastomers, polyolefin elastomers, polyurethane elastomers, polyester elastomers, polyamide elastomers, polybutadiene elastomers, polyisoprene elastomers, acrylonitrile elastomers, and acrylic elastomers. 【0091】 Other thermoplastic resins include, for example, polycaprolactone resin, phenoxy resin, and thermoplastic epoxy resin. 【0092】 As the non-fluorinated thermoplastic resin, one or more selected from polyamide, polyaryletherketone, polyphenylene sulfide, polysulfone, thermoplastic polyimide, polyetherimide, polycarbonate, liquid crystal polymer, and polyarylate are preferred, with polyaryletherketone and polyphenylene sulfide being more preferred from the viewpoint of mechanical properties and heat resistance. 【0093】 From the viewpoint of mechanical properties and heat resistance, polyether ketone (hereinafter also referred to as "PEK"), polyether ether ketone (hereinafter also referred to as "PEEK"), or polyether ketone ketone (hereinafter also referred to as "PEKK") are preferred as the polyaryl ether ketone, with PEEK being particularly preferred. Two or more types of polyaryl ether ketone may be used in combination, but it is preferable to use one type alone. 【0094】 As the PEEK, a PEEK having repeating units represented by the following formula (I) is preferred. 【0095】 (I) In the above equation (I), x1 and y1 are independently 0 or 1, and z1 is 0, 1, or 2. 【0096】The melting point of polyaryletherketone is preferably 200 to 430°C, more preferably 250 to 400°C, and even more preferably 280 to 380°C. If the melting point of polyaryletherketone is above the lower limit of the above range, the heat resistance of the insulating coating material is further improved. If the melting point of polyaryletherketone is below the upper limit of the above range, deterioration of physical properties due to thermal decomposition of the fluorine-containing polymer (A) during the manufacture of flat wire can be suppressed, and the properties of the fluorine-containing polymer (A) (flexibility, impact resistance, chemical resistance, etc.) can be maintained. 【0097】 The melt viscosity of polyaryletherketone is 122 sec at a temperature of 390°C. －１ In the measurement conditions, 10 to 690 Pa·s is preferred, 50 to 500 Pa·s is more preferred, and 100 to 400 Pa·s is even more preferred. The MFR of polyaryletherketone at a temperature of 372°C and a load of 49 N is preferably 20.0 to 150.0 g / 10 min, and more preferably 21.0 to 200.0 g / 10 min. When the melt viscosity and MFR of polyaryletherketone are within the above ranges, it becomes easier to adjust the MFR of the insulating coating material to the above ranges. 【0098】 Polyaryl ether ketones may be commercially available or synthesized from various raw materials by various methods. Examples of commercially available PEEK include Victrex PEEK (manufactured by Victrex), the VESTAKEP series (manufactured by Daicel-Evonik), and Ketaspire (manufactured by Solvay Specialty Polymers). An example of a commercially available PEKK is Kepstan (manufactured by Arkema). 【0099】 The total content of the fluorine-containing polymer (A) and the non-fluorine thermoplastic resin (B) relative to the total mass of the insulating coating material is preferably 50% by mass or more, more preferably 70% by mass or more, and may also be 100% by mass. 【0100】The insulating coating material does not have to contain a non-fluorine thermoplastic resin (B). If the insulating coating material does not contain a non-fluorine thermoplastic resin (B), it may consist only of a fluorine-containing resin (A1) or only of a fluorine-containing elastomer (A2). The amount of fluorine-containing elastomer (A2) is preferably 60% by mass or less, and more preferably 50% by mass or less, relative to the total mass of the fluorine-containing copolymer (A). If the insulating coating material contains a non-fluorine thermoplastic resin (B), the content of the fluorine-containing polymer (A) relative to the total mass of the fluorine-containing polymer (A) and the non-fluorine thermoplastic resin (B) in the insulating coating material is preferably 1% by mass or more, more preferably 5 to 99% by mass, and even more preferably 10 to 40% by mass. In other words, when the insulating coating material contains a non-fluorinated thermoplastic resin (B), the content of the non-fluorinated thermoplastic resin (B) relative to the total mass of the fluorinated polymer (A) and the non-fluorinated thermoplastic resin (B) in the insulating coating material is preferably 99% by mass or less, more preferably 1 to 95% by mass, and even more preferably 60 to 90% by mass. When the non-fluorinated thermoplastic resin (B) is above the lower limit, the tensile breaking strength of the insulating coating material is excellent. 【0101】<Other Components> Other components include polymers other than fluorine-containing copolymers (A) and non-fluorine thermoplastic resins (B), fillers, pigments, and other additives. Specific examples of fillers include resins and inorganic fillers. Resins include fibrous resins such as aramid fibers and liquid crystal polyester fibers, and powdered resins such as polytetrafluoroethylene. Inorganic fillers include fibrous fillers such as glass fibers, carbon fibers, boron fibers, and stainless steel microfibers; and powdered fillers such as talc, mica, graphite, molybdenum disulfide, calcium carbonate, silica, silica-alumina, alumina, and titanium dioxide. Other examples include hydrotalcites and metal oxides, such as zinc oxide, magnesium oxide, titanium oxide, lead oxide, and copper oxide. Metal powders can also be used, such as stainless steel, iron-based materials, titanium, copper, and nickel powders. Fillers may be used individually or in combination of two or more types. Pigments include coloring pigments such as organic pigments and inorganic pigments. Specific examples include carbon black (black pigment), iron oxide (red pigment), aluminum cobalt oxide (blue pigment), copper phthalocyanine (blue and green pigments), perylene (red pigment), and bismuth vanadate (yellow pigment). Other components may be used individually or in combination of two or more. 【0102】 [Crosslinking Aids] Crosslinking aids have two or more unsaturated bonds in one molecule. Examples of crosslinking aids include triallyl cyanurate, triallyl isocyanurate, bismaleimide, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, trimethylolpropane trimethacrylate, and divinylbenzene. Among these, triallyl isocyanurate, also known as Tyke, is preferred due to its high thermal stability. 【0103】 The crosslinking aid is preferably added in an amount of 0.5 to 20 parts by mass, and more preferably in an amount of 2 to 8 parts by mass, per 100 parts by mass of fluororesin. 【0104】The insulating coating material may contain an antioxidant. The antioxidant has at least one of a phenol group and a phosphorus atom, and a molecular weight of 600 or more. Preferably, the antioxidant has both a phenol group and a phosphorus atom. The following are some preferred examples of antioxidants, but two or more of these may be selected and used in any combination. 【0105】 Antioxidants having both a phenol group and a phosphorus atom include, for example, 2-tert-butyl-6-methyl-4-[3-(2,4,8,10-tetratert-butylbenzo[d][1,3,2]benzodioxaphosfepin-6-yl)oxypropyl]phenol and phosphorus-modified novolac-type phenolic resins. Among these, 2-tert-butyl-6-methyl-4-[3-(2,4,8,10-tetratert-butylbenzo[d][1,3,2]benzodioxaphosfepin-6-yl)oxypropyl]phenol is preferred for its excellent thermal stability. 【0106】 Antioxidants having a phenol group include bisphenol A, bisphenol AF, phenol, cresol, p-phenylphenol, m-phenylphenol, o-phenylphenol, allylphenol, p-hydroxybenzoic acid, ethyl p-hydroxybenzoate, and hindered phenols. 【0107】 Examples of hindered phenols include octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionic acid, and bis[3-(3,5-zi-tert-butyl-4-hydroxyphenyl)propionic acid][2,2-bis[[1-oxo-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propoxy]methyl]propane]-1,3-diyl. 【0108】As antioxidants containing a phosphorus atom, phosphorus compounds containing a trivalent phosphorus atom are preferred. The trivalent phosphorus atom exists in the molecule in the form of a phosphine group or a phosphonic acid ester group. The trivalent phosphorus atom exhibits antioxidant properties through self-oxidation to a pentavalent state, thereby decomposing peroxides (eliminating radicals generated from peroxides). 【0109】Antioxidants containing a trivalent phosphorus atom include, for example, trioctyl phosphite, trilauryl phosphite, tridecyl phosphite, (octyl)diphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, triphenyl phosphite, tris(butoxyethyl) phosphite, tris(nonylphenyl) phosphite, distearyl pentaerythritol diphosphite, and tetra(tridecyl)-1,1,3-tris(2-methyl-5-t-butyl-4-hydroxyphenyl)butanediphosphate. Phyto, tetra(C12-C15 mixed alkyl)-4,4'-isopropylidenediphenyl diphosphite, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-t-butylphenol) diphosphite, tris(3,5-di-t-butyl-4-hydroxyphenyl) phosphite, tris(mono / di mixed nonylphenyl) phosphite, hydrogenated-4,4'-isopropylidenediphenol polyphosphite, bis(octylphenyl)bis[4,4'-butylidenebis(3-methyl-6-t-butylphenol] Tris[4,4'-isopropylidenebis(2-t-butylphenol)]phosphite, phenyl(4,4'-isopropylidenediphenol)pentaerythritol diphosphite, distearylpentaerythritol diphosphite, tris[4,4'-isopropylidenebis(2-t-butylphenol)]phosphite, di(isodecyl)phenyl phosphite, 4,4'-isopropylidenebis(2-t-butylphenol)bis(nonylphenyl)phosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide , bis(2,4-di-t-butyl-6-methylphenyl)ethyl phosphite, 2-[{2,4,8,10-tetra-t-butyldibenz[d,f][1.3.2]-dioxaphosfepin-6-yl}oxy]-N,N-bis[2-[{2,4,8,10-tetra-t-butyldibenz[d,f][1.3.2]-dioxaphosfepin-6-yl}oxy]ethyl]ethanamine, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenz[d,Examples include f][1.3.2]-dioxaphosfepine and bis(dialkylphenyl)pentaerythritol diphosphite esters. 【0110】 Antioxidants containing trivalent phosphorus atoms may be commercially available. Examples of commercially available products include Irgaphos 168 (registered trademark, manufactured by Ciba Specialty Chemicals), Irgaphos 12 (registered trademark, manufactured by Ciba Specialty Chemicals), Irgaphos 38 (registered trademark, manufactured by Ciba Specialty Chemicals), Adekastab 329K (registered trademark, manufactured by Asahi Denka), Adekastab PEP36 (registered trademark, manufactured by Asahi Denka), Adekastab PEP-8 (registered trademark, manufactured by Asahi Denka), Sandstab P-EPQ (registered trademark, manufactured by Clariant), Weston 618 (registered trademark, manufactured by GE), Weston 619G (registered trademark, manufactured by GE), Ultranox 626 (registered trademark, manufactured by GE), and Sumirizer GP (registered trademark, manufactured by Sumitomo Chemical). 【0111】 The antioxidant has a molecular weight of 600 or more. Preferably, the molecular weight of the antioxidant is between 600 and 50,000, and more preferably between 600 and 3,000. A molecular weight of 600 or more provides excellent thermal stability. If the molecular weight of the antioxidant is below the preferred upper limit, it exhibits excellent dispersibility with other polymer components. 【0112】 The antioxidant is preferably added in an amount of 0.001 to 20 parts by mass, and more preferably 0.01 to 5 parts by mass, per 100 parts by mass of the fluorine-containing copolymer contained in the insulating coating material. If the amount of antioxidant is above the preferred lower limit, the thermal stability is excellent. If the amount of antioxidant is below the preferred upper limit, the mechanical properties are excellent. 【0113】 Furthermore, specific examples of additives such as fillers, plasticizers, and flame retardants include, for example, the components described in paragraphs

[0042] to

[0048] of International Publication No. 2019-198771. 【0114】<Method for Manufacturing Flat Rectangular Wire> The above-described flat rectangular wire can be manufactured by using an extruder equipped with a die to melt a composition containing a fluorine-containing polymer (A), and then extruding the molten composition from the die around a flat rectangular copper conductor, thereby coating the flat rectangular copper conductor with the molten composition and forming the insulating coating material. In addition to the fluorine-containing polymer (A), the above composition may also contain a non-fluorine thermoplastic resin (B). Furthermore, in addition to the fluorine-containing copolymer (A) and the non-fluorine thermoplastic resin (B), the above-described other components may be added to the extruder. 【0115】 (Composition) The composition comprises a fluorine-containing polymer (A). The composition may further comprise a non-fluorine thermoplastic resin (B). The composition may further comprise other components besides the fluorine-containing polymer (A) and the non-fluorine thermoplastic resin (B), as long as these do not significantly impair its properties. 【0116】 The total content of the fluorine-containing polymer (A) and the non-fluorine thermoplastic resin (B) relative to the total mass of the composition is preferably 50% by mass or more, more preferably 70% by mass or more, and may also be 100% by mass. 【0117】 The composition does not have to contain a non-fluorinated thermoplastic resin (B). If the composition does not contain a non-fluorinated thermoplastic resin (B), the composition may consist only of a fluorinated resin (A1) or only of a fluorinated elastomer (A2). The amount of fluorinated elastomer (A2) is preferably 60% by mass or less, and more preferably 50% by mass or less, relative to the total mass of the fluorinated copolymer (A). If the composition contains a non-fluorinated thermoplastic resin (B), the content of the fluorinated polymer (A) relative to the total mass of the fluorinated polymer (A) and non-fluorinated thermoplastic resin (B) in the composition is preferably 1% by mass or more, more preferably 1 to 99% by mass, and even more preferably 10 to 40% by mass. That is, if the composition contains a non-fluorinated thermoplastic resin (B), the content of the non-fluorinated thermoplastic resin (B) relative to the total mass of the fluorinated polymer (A) and non-fluorinated thermoplastic resin (B) in the composition is preferably 99% by mass or less, more preferably 1 to 99% by mass, and even more preferably 60 to 90% by mass. 【0118】At a temperature of 372°C and a load of 49N, the MFR of the composition is preferably 5.0 to 300.0 g / 10 min, more preferably 15.0 to 250.0 g / 10 min, and even more preferably 40.0 to 200.0 g / 10 min. 【0119】 (Manufacturing Conditions) Examples of extruders include twin-screw extruders and single-screw extruders, with twin-screw extruders being preferred. The die opening is rectangular in shape. The cylinder temperature and die temperature of the extruder are set according to the type of fluorine-containing polymer (A) and non-fluorine thermoplastic resin (B). The cylinder temperature of the extruder is preferably 50 to 450°C, more preferably 80 to 440°C, and even more preferably 90 to 430°C. The die temperature is preferably 100 to 420°C, more preferably 120 to 400°C, and even more preferably 150 to 380°C. If the cylinder temperature and die temperature of the extruder are above the lower limit, the miscibility of the materials by kneading will be good. If the cylinder temperature and die temperature of the extruder are below the upper limit, thermal degradation of the fluorine-containing polymer (B) will be easier to suppress. The residence time in the extruder is preferably 10 seconds to 30 minutes. The screw rotation speed of the extruder is preferably 0.5 to 100 rpm. 【0120】 It is preferable to preheat the rectangular copper conductor in an oxygen-containing gas atmosphere. Examples of oxygen-containing gases include pure oxygen, air, and gases obtained by diluting oxygen with an inert gas such as nitrogen. The preheating temperature is preferably 160°C or higher, more preferably 200°C or higher, even more preferably 230°C or higher, and still more preferably 250°C or higher. The upper limit of the preheating temperature is, for example, preferably 600°C or lower, more preferably 500°C or lower, and still more preferably 400°C or lower. If the preheating temperature is above the lower limit, the oxygen atom content on the surface of the rectangular copper conductor tends to increase. If the preheating temperature is below the upper limit, the strength of the rectangular copper conductor is excellent. 【0121】 The preheating time can be adjusted as appropriate depending on the preheating temperature and preheating means, but for example, 1 to 600 seconds is preferred, 2 to 300 seconds is more preferred, and 3 to 100 seconds is even more preferred. 【0122】As a preheating method, it is preferable to use a method that can preheat not only the surface of the flat copper conductor but also the interior. Examples of such preheating methods include optical heating, hot air heating, radiant heating, gas burner heating, induction heating, and dielectric heating. In particular, a preheating method that generates a magnetic field and heats by the internal resistance of the metal is preferred, and among such preheating methods, induction heating is particularly preferred. For example, if a halogen heater capable of heating only the surface of the flat copper conductor is selected as the preheating method, the oxygen atom content on the surface of the flat copper conductor does not increase easily, even if the preheating temperature is increased, as shown in the embodiments described later. 【0123】 (Drawdown Ratio) In the method for manufacturing rectangular wires of this embodiment, the drawdown ratio (hereinafter also referred to as "DDR") calculated by the following formula 1 is preferably less than 15, more preferably 0.5 or more and less than 10.0, even more preferably 0.5 to 5, and particularly preferably 0.8 to 1.5. When the DDR is above the lower limit, it is easier to obtain rectangular wires with excellent surface smoothness of the insulating coating film. When the DDR is below (or less than) the upper limit, the adhesion between the rectangular copper conductor and the insulating coating film is easily improved. 【0124】 DDR = (D Ａ -C Ａ ) / (F Ａ -C Ａ ) Equation 1 In the above Equation 1, D Ａ The die opening area (mm²) ２ ) and C Ａ This is the area of ​​the cross-section of the flat copper conductor in the direction perpendicular to the axial direction (mm²). ２ ) and F Ａ This is the area of ​​the cross-section (mm²) perpendicular to the axis of the rectangular wire. ２ ) 【0125】 D Ａ This can be calculated from equation 2 below. D Ａ = D Ｌ ×D Ｓ Equation 2 In the above Equation 2, D Ｌ D is the inner dimension (mm) of the long side of the rectangular opening surface of the die. Ｓ This is the inner dimension (mm) of the shorter side of the rectangular opening surface of the die. 【0126】 C ＡThis can be calculated from equation 3 below. C Ａ = C Ｌ ×C Ｓ Equation 3 In the above Equation 3, C Ｌ C is the length (mm) of the rectangular cross-section of the flat copper conductor in a direction perpendicular to the axial direction, Ｓ This is the length (mm) of the shorter side of the rectangular cross-section of the flat copper conductor, perpendicular to the axial direction. 【0127】 F Ａ F can be found from equation 4 below. Ａ = F Ｌ ×F Ｓ Equation 4 In the above Equation 4, F Ｌ F is the length (mm) of the long side of the rectangular cross-section perpendicular to the axis direction of the rectangular line. Ｓ This is the length (mm) of the shorter side of the rectangular cross-section perpendicular to the axis of the rectangular wire. 【0128】 In this embodiment, it is preferable to employ a so-called pressure molding method, in which the insulating coating material is formed under pressure. By employing a pressure molding method, the DDR tends to be less than (or less than) the above upper limit compared to the conventional tube molding method, and as a result, it becomes easier to obtain a flat wire with excellent surface smoothness of the insulating coating film and excellent conformability of the insulating coating film to the flat copper conductor during bending deformation. 【0129】 (Applications) The flat wire of the present invention can be suitably used in, for example, isolation amplifiers, isolation transformers, automobile alternators, hybrid vehicles, electric ships, electric aircraft, electric motors for electric vertical take-off and landing aircraft, etc. It can also be used as various types of electric wires (wrapping wires, automotive wires, robotic wires) and as coil windings (magnet wires). 【0130】 The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following examples, Examples 1 to 11 are examples, and Examples 12 to 16 are comparative examples. 【0131】<Evaluation Method> (Oxygen Atom Content on the Surface of Flat Copper Conductors) The oxygen atom content on the surface of flat copper conductors was measured by SEM-EDX under the following conditions. A SEM-EDX (JEOL Ltd., JSM-IT700HR) was used as the measuring instrument. [Measurement Conditions] Acceleration voltage: 15kV Live time: 30s Vacuum level: Under vacuum (High Vacuum mode) Magnification: 100x 【0132】 (MFR of insulating coating material) After preheating the insulating coating material at 372°C for 5 minutes, the MFR at 49N was measured according to JIS K 7210-1:2014. The measurement was performed at 372°C. If the MFR exceeds 100g / 10min, the preheating time may be set to 30 seconds to 180 seconds. 【0133】 (MFR of fluororesin (A1) and non-fluorothermoplastic resin (B)) The MFR at 49N was measured according to JIS K 7210-1:2014. The measurement was performed at 372°C. 【0134】 (MFR of fluorine-containing elastomer (A2)) The MFR at 21N was measured according to JIS K 7210-1:2014. The measurement was performed at 230°C. 【0135】 (Melting viscosity of fluorine-containing copolymer (A) and non-fluorine thermoplastic resin (B)) The melting viscosity was measured using a capillograph (manufactured by Toyo Seiki Co., Ltd., capillary length L: 10 mm, capillary inner diameter r: 1.0 mm, piston diameter D: 9.55 mm). For fluorine-containing resin (A1) and non-fluorine thermoplastic resin (B), the temperature was 390°C and the shear rate was 122 sec. －１ Measurements were taken at the following conditions: For fluorine-containing elastomer (A2), temperature: 300°C, shear rate: 122 sec. －１ The measurement was performed using [this method]. 【0136】 (Melting points of fluororesin (A1) and non-fluorothermoplastic resin (B)) Using a differential scanning calorimeter (manufactured by Seiko Instruments), the melting peaks of fluororesin (A1) and non-fluorothermoplastic resin (B) were recorded when the temperature was increased at a rate of 10°C / min, and the temperature corresponding to the maximum value was defined as the melting point. 【0137】(Mooney viscosity (ML) of fluorine-containing elastomer (A2) １＋１０ The temperature was measured at 121°C using an SMV-201 (manufactured by Shimadzu Corporation) in accordance with JIS K 6300-1:2000 (corresponding international standards ISO 289-1:2005, ISO 289-2:1994). 【0138】 (Storage modulus G' of fluorine-containing elastomer (A2)) The storage modulus was measured using an RPA2000 (Alpha Technologies) in accordance with ASTM D6204 under conditions of 100°C and 50 cpm. 【0139】 (Tensile Breaking Strength of Insulating Coatings) The tensile breaking strength of the insulating coatings was measured in accordance with ASTM D 638. For the measurement samples, Type V dumbbell-shaped test specimens obtained by melt-molding the compositions used in the manufacture of each example of insulating coating were used. Note that in Table 1, MPa and kgf / mm² are used. ２ Display in both units. 【0140】 (Material fracture strength of insulating coating material) The tensile fracture strength (kgf / mm) of the insulating coating material obtained above ２ The material fracture strength of the insulating coating was obtained by multiplying the width of the flat copper conductor and the average thickness of the coating of the insulating coating material by the value of ). 【0141】 (Average coating thickness) A 5m length of rectangular wire was taken, and the thickness of the insulating coating on the long side of the rectangular cross-section perpendicular to the axial direction was measured every 100mm (only on the side that contacts the upper inner surface of the die during molding). The arithmetic mean of the measured values ​​(mm) was taken as the average thickness. 【0142】(Comparison of Material Breaking Strength and Interfacial Strength) The comparison of the "material breaking strength" of the insulating coating on a rectangular wire and the "interfacial strength" between the rectangular copper conductor and the insulating coating was carried out as follows. A 3 cm section of rectangular wire was taken, and the insulating coating was cut circumferentially in the axial center using a cutter. The cut surface was grasped, and 1 mm of the coating was peeled off with tweezers in a 180° direction to form the gripping portion. Then, both ends of the rectangular wire were fixed to a jig, and the wire was pulled at a tensile speed of 100 mm / min at room temperature (approximately 25°C) using a Tensilon universal material testing machine RTF-1350 to attempt to peel the insulating coating from the rectangular copper conductor. In this case, if the insulating coating broke at a peeling distance of less than 2 cm (i.e., the length of the rectangular copper conductor exposed after the insulating coating was peeled off from the start of pulling was less than 2 cm), it was determined that the interfacial strength > material breaking strength. Note that "fracture" refers to the rupture of the insulating coating material when pulled in a 180° direction. In Table 1, ○ indicates that the interfacial strength > material fracture strength, and × indicates that the interfacial strength ≤ material fracture strength. 【0143】 (Adhesion of Flat Copper Conductors) Adhesion was tested in accordance with "5.5 Adhesion Test" of JIS 3216-3:2011, specifically "5.5.1 Enameled Flat Wire". The following criteria were used for evaluation. ◎, ○, and △ are considered passing grades. ◎: The flat copper conductor broke without any lifting of the coating when stretched by 15% or more. ○: Lifting of the coating occurred from the flat copper conductor when stretched by 10% or more but less than 15%. △: Lifting of the coating occurred from the flat copper conductor when stretched by 5% or more but less than 10%. ×: Lifting of the coating occurred from the flat copper conductor when stretched by less than 5%. 【0144】 (Gap between the rectangular copper conductor and the coating) After bending a rectangular wire edgewise at 120°, 3 cm before and after the bend was cut. Then, the rectangular wire was embedded in epoxy resin, and the cross-section was exposed by polishing. Finally, the presence or absence of a gap between the rectangular copper conductor and the coating was confirmed by SEM-EDX observation. 5 μm ２ If the above-mentioned space is present, it is determined that there is an air gap. When an air gap is present, the adhesion of the coating to the flat copper conductor during bending is poor. 【0145】 <Materials used> 【0146】[Fluorine-containing copolymer (A)] The following materials were used as fluorine-containing copolymer (A). Note that C2 units refer to CH ２ =CH(CF ２ ) ２ It is a unit based on F, and the C4 unit is CH ２ =CH(CF ２ ) ４ These are units based on F. • Fluorine-containing resin (A1-1): Fluorine-containing resin with a molar ratio of TFE units:PPVE units:NAH units = 97.9:2.0:0.1 (melting point: 300°C, specific gravity: 2.13, MFR: 16g / 10min). • Fluorine-containing resin (A1-2): Fluorine-containing resin with a molar ratio of TFE units:PPVE units = 98.0:2.0 (melting point: 305°C, MFR: 28g / 10min). • Fluorine-containing resin (A1-3): Fluorine-containing resin with a molar ratio of TFE units:E units:C2 units:IAH units = 58.5:39:2.4:0.1 (melting point: 240°C, MFR: 28g / 10min). • Fluorine-containing resin (A1-4): A fluoroine-containing resin with a molar ratio of TFE units:E units:C4 units = 54:46:1.4 (melting point: 257°C, MFR: 11g / 10min). • Fluorine-containing resin (A1-5): A fluoroine-containing resin with a molar ratio of TFE units:E units:C4 units = 60:40:3.3 (melting point: 225°C, MFR: 25g / 10min). • Fluorine-containing elastomer (A2-1): A fluoroine-containing elastomer with a molar ratio of TFE units:P units = 56:44, without iodine atoms, MFR: 11g / 10min, melt viscosity: 270 Pa·s, specific gravity: 1.55, Mooney viscosity (ML) １＋１０ (At 121°C): 100, Storage modulus G': 390 kPa). 【0147】 [Non-fluorinated thermoplastic resins (B)] ・Polyaryl ether ketone (B1-1): PEEK (manufactured by Daicel Evonik, product name "VESTAKEP3300G", melting point: 340°C, MFR: 21 g / 10 min, melt viscosity: 700 Pa / s, specific gravity: 1.32). ・Polyphenylene sulfide (B1-2) (manufactured by Solvay Specialty Polymers, product name "Ryton QC160P", melting point: 280°C, MFR: 53.8 g / 10 min (measurement conditions 297°C, 49 N)). 【0148】(Example 1) [Preheating of Flat Copper Conductors] Flat wires were manufactured by extruding the compositions listed in Table 1 under the following conditions. DDR was set to 1. In the wire extruding, the so-called pressure molding method was employed, in which the insulating coating material is formed under pressure. [Preheating Conditions for Flat Copper Conductors] Flat copper conductor: Thickness 1.5 mm x Width 3.0 mm (Cross-sectional area 4.5 mm) ２ ) Flat rectangular copper wire. Preheating method for flat rectangular copper conductor: induction heating oven. Preheating temperature of flat rectangular copper conductor: 310°C. Preheating time of flat rectangular copper conductor: 10 seconds. Temperature of flat rectangular copper conductor 15 cm before the die: 250°C. [Wire extrusion conditions] Die temperature: 400°C. Cylinder temperature: 320-380°C. The preheating conditions and wire extrusion conditions for flat rectangular copper conductors in Examples 2-16 are shown in Table 1 below. 【0149】 (Examples 2-16) Flat rectangular wires were manufactured in the same manner as in Example 1, except that the compositions with the formulations listed in Table 1 were used, and the preheating and wire extrusion conditions were also listed in Table 1. The cross-sectional area of ​​the flat rectangular copper conductor was calculated as thickness × width, as in Example 1. As shown in Table 1, halogen heaters were used as the preheating means in Examples 13 and 15. In Example 14, a so-called tube molding method was adopted, in which the insulating coating material was formed substantially under normal pressure. 【0150】 The flat copper conductors, insulating coatings, and flat wires in each example were evaluated as described above. The results are shown in Table 1. 【0151】 【0152】Examples 1-11 showed interfacial strength > material fracture strength, indicating excellent adhesion between the rectangular copper conductor and the insulating coating. This high adhesion was thought to be due to the high oxygen atom concentration on the surface of the rectangular copper conductor. Example 12 showed interfacial strength ≤ material fracture strength, indicating poor adhesion to the insulating coating. This was thought to be due to a low preheating temperature of the rectangular copper conductor and a low oxygen atom concentration on the surface of the rectangular copper conductor. Examples 13 and 15 also showed interfacial strength ≤ material fracture strength, indicating poor adhesion to the insulating coating. Although the preheating temperature of the rectangular copper conductor was high, heating with a halogen heater did not conduct heat to the rectangular copper conductor, and this was thought to be due to a low oxygen atom concentration on the surface of the rectangular copper conductor. Example 14 also showed interfacial strength ≤ material fracture strength, indicating poor adhesion to the insulating coating. Although the oxygen atom concentration on the surface of the rectangular copper conductor was high, this was thought to be due to the manufacturing process using DDR 15. In Example 16, the interfacial strength was less than or equal to the material fracture strength, indicating poor adhesion to the insulating coating. Although the oxygen atom concentration on the surface of the rectangular copper conductor was high, this was thought to be due to the fact that the insulating coating did not contain a fluorine-containing polymer (A).

Claims

1. A rectangular wire comprising a rectangular copper conductor having a rectangular cross-section perpendicular to the axial direction, and a coating of insulating material directly covering the entire circumferential direction of the rectangular copper conductor, wherein the cross-sectional area of ​​the rectangular copper conductor is 2.0 mm². ２ The above is true, wherein the average thickness of the insulating coating is 30 to 500 μm, the insulating coating contains a fluorine-containing polymer, and the interfacial strength between the rectangular copper conductor and the insulating coating is higher than the material fracture strength of the insulating coating.

2. The rectangular copper wire according to claim 1, wherein the oxygen atom content on the surface of the rectangular copper conductor is 1.0% by mass or more.

3. The rectangular wire according to claim 1, wherein the material fracture strength of the insulating coating material is 0.30 to 3.40 kgf.

4. The fluorine-containing polymer is a fluorine-containing resin having a melting point of 160°C or higher, as described in claim 1.

5. The rectangular wire according to claim 4, wherein the fluororesin has units based on tetrafluoroethylene.

6. The flat wire according to claim 1, wherein the fluorine-containing polymer is a fluorine-containing elastomer.

7. The fluorine-containing elastomer having units based on tetrafluoroethylene, as described in claim 6.

8. The flat wire according to claim 1, wherein the coating of the insulating coating material is a coating of insulating coating material formed by extrusion molding.

9. The rectangular wire according to claim 1, wherein the insulating coating material further comprises a non-fluorine thermoplastic resin.

10. The flat wire according to claim 9, wherein the non-fluorine thermoplastic resin comprises one or more selected from the group consisting of polyarylether ketones and polyphenylene sulfides.

11. The method for manufacturing a flat wire according to any one of claims 1 to 10, comprising melting a composition containing the fluoropolymer using an extruder equipped with a die, and extruding the melted composition from the die around the flat copper conductor to coat the melted composition around the flat copper conductor, thereby forming the insulating coating material, wherein the draw-down ratio DDR calculated by the following formula 1 is less than 15. DDR = (D Ａ - C Ａ ) / (F Ａ - C Ａ ) Formula 1 In Formula 1, D Ａ is the opening area (mm ２ ) of the die, C Ａ is the cross-sectional area (mm ２ ) of a cross-section perpendicular to the axial direction of the flat copper conductor, and F Ａ is the cross-sectional area (mm ２ ) of a cross-section perpendicular to the axial direction of the flat wire.

12. The method for manufacturing a rectangular wire according to claim 11, wherein the rectangular copper conductor is a rectangular copper conductor that has been preheated to 160°C or higher in an oxygen-containing gas atmosphere.

13. The method for manufacturing a rectangular wire according to claim 12, wherein the preheating means for the rectangular copper conductor is a method of generating a magnetic field and heating it by the internal resistance of the metal.

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