insulated wire

Abstract

To provide an insulated wire which is excellent in machinability of a molding, and is also excellent in heat resistance and a partial discharge inception voltage.SOLUTION: An insulated wire has a covering material covering a conductor and its outer periphery, wherein the covering material is made of a polyarylene sulfide resin composition that contains, with respect to 100 pts.wt. of a polyarylene sulfide resin (A), 35-80 pts.wt. of a reactive functional group modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B), and 10-80 pts.wt. of a fluororesin (C).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an insulated wire, and more particularly to an insulated wire which has excellent productivity and an improved partial discharge inception voltage, and which is made of a polyarylene sulfide resin composition as a coating material or an exterior material. The polyarylene sulfide resin composition has heat resistance, excellent dielectric breakdown voltage resistance, excellent dielectric properties, and excellent toughness such as impact resistance. [Background technology]

[0002] The automotive industry is working to develop core technologies for increasing the efficiency, size, and weight of the motors and generators used in hybrid and electric vehicles. One method for achieving higher output is to increase the coil space within the stator core. One way to increase the coil space is to use rectangular wire instead of the round wire that has traditionally been used for coils.

[0003] In this case, the insulating wire coating material is required to have a high dielectric breakdown strength, especially a high partial discharge inception voltage, and it is known that the relationship between the partial discharge inception voltage and the relative dielectric constant is expressed by the following formula (1) (Dakin's formula) (see, for example, Non-Patent Document 1). According to formula (1), in order for the wire to have a high partial discharge inception voltage, the insulating wire coating material is required to have a low relative dielectric constant relative to the resin composition. V=163(t / εr) 0.46 (1) (Here, V is the partial discharge inception voltage (Vrms), t is the thickness of the insulating layer (μm), and εr is the relative dielectric constant of the insulating layer.) Furthermore, a control cable has been proposed in which a liner is formed by extruding a composition made by blending polyphenylene sulfide resin with an elastomer that is an α-olefin-α,β-unsaturated acid glycidyl ester copolymer into a tubular shape, and the liner is covered with a heat-resistant synthetic resin (see, for example, Patent Document 1). Also proposed is a composition that has excellent heat resistance and electrical insulation properties, made from polyphenylene sulfide resin and an ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer having a reactive functional group (see, for example, Patent Document 2).

[0004] Furthermore, an insulated wire has been proposed that has sliding properties that are less likely to damage the coating by using a fluororesin and a thermosetting resin as a binder (see, for example, Patent Document 3), and it has also been proposed to ensure the tensile strength and tensile elongation at break of a resin composition by increasing the elongational viscosity of a polyarylene sulfide when melted (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3159700 [Patent Document 2] Patent No. 4999077 [Patent Document 3] Patent No. 4782906 [Patent Document 4] Patent No. 3618485 [Non-patent literature]

[0006] [Non-Patent Document 1] Furukawa Electric Times No. 133 (2014) p11-18 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the control cable proposed in Patent Document 1, the relative dielectric constant of the resin composition of the insulating coating material is relatively high, which results in a relatively high partial discharge inception voltage. Therefore, in order to ensure a certain partial discharge inception voltage, it is necessary to increase the thickness of the coating layer, which poses a problem of limiting the motor's ability to increase output and make it more compact. Similarly, the proposal in Patent Document 2 also has the problem of a relatively high partial discharge inception voltage due to the relatively high relative dielectric constant of the resin composition of the insulating coating material.

[0008] Furthermore, Patent Document 3 does not mention the insulating performance, particularly the partial discharge inception voltage or relative dielectric constant characteristics, and Patent Document 4 also has a problem with the relative dielectric constant.

[0009] Therefore, an object of the present invention is to provide an insulated wire suitable for achieving high efficiency, which contains a polyarylene sulfide resin composition as a coating or exterior material, which has the heat resistance, chemical resistance, dielectric breakdown strength, and low dielectric constant inherent to polyarylene sulfide resins and does not generate cracks even after thermal shock cycles or molding. [Means for solving the problem]

[0010] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that by using a polyarylene sulfide resin composition containing a polyarylene sulfide resin, a specific ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer, and a fluororesin as a coating material or exterior packaging material, an insulated wire can be obtained that has heat resistance, chemical resistance, dielectric breakdown strength, and a low dielectric constant, is resistant to thermal shock cycles and cracks, and achieves an improved partial discharge inception voltage, thereby completing the present invention.

[0011] That is, the present invention relates to an insulated wire having a conductor and a covering material covering the conductor, characterized in that the covering material is made of a polyarylene sulfide resin composition containing 100 parts by weight of a polyarylene sulfide resin (A), 35 to 80 parts by weight of a reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B), and 10 to 80 parts by weight of a fluororesin (C).

[0012] The present invention will be described in detail below.

[0013] The insulated wire of the present invention includes a conductor and an insulating covering material, and the covering material located around the conductor is formed by molding a polyarylene sulfide resin composition containing 100 parts by weight of a polyarylene sulfide resin (hereinafter sometimes simply referred to as PAS resin) (A), 35 to 80 parts by weight of a reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (hereinafter sometimes simply referred to as copolymer) (B), and 10 to 80 parts by weight of a fluororesin (C).

[0014] The covering material constituting the insulated wire of the present invention is formed by molding a PAS resin composition containing 100 parts by weight of PAS resin (A), 35 to 80 parts by weight of copolymer (B), and 10 to 80 parts by weight of fluororesin (C) into a covering material.

[0015] The PAS resin (A) constituting the PAS resin composition in this case may be any resin that falls within the category generally referred to as a PAS resin. Examples of such PAS resins include homopolymers or copolymers composed of p-phenylene sulfide units, m-phenylene sulfide units, o-phenylene sulfide units, phenylene sulfide sulfone units, phenylene sulfide ketone units, phenylene sulfide ether units, and biphenylene sulfide units. Specific examples of such PAS resins include poly(p-phenylene sulfide) (hereinafter sometimes simply referred to as PPS), polyphenylene sulfide sulfone, polyphenylene sulfide ketone, and polyphenylene sulfide ether. Of these, PPS is preferred because it results in a PAS resin composition and insulated wire that are particularly excellent in heat resistance and strength properties.

[0016] The PAS resin (A) can be produced by a method known for producing PAS resins, for example, by polymerizing an alkali metal sulfide salt and a polyhaloaromatic compound in a polar solvent. Examples of polar organic solvents include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, cyclohexylpyrrolidone, dimethylformamide, and dimethylacetamide. Examples of alkali metal sulfide salts include anhydrous or hydrated sodium sulfide, rubidium sulfide, and lithium sulfide. The alkali metal sulfide salt may also be a product of reacting an alkali metal hydrosulfide salt with an alkali metal hydroxide. Examples of polyhaloaromatic compounds include p-dichlorobenzene, p-dibromobenzene, p-diiodobenzene, m-dichlorobenzene, m-dibromobenzene, m-diiodobenzene, 4,4'-dichlorodiphenyl sulfone, 4,4'-dichlorobenzophenone, 4,4'-dichlorodiphenyl ether, and 4,4'-dichlorodibiphenyl.

[0017] Examples of PAS resin (A) include linear PAS resins, PAS resins that have been heat-treated in oxygen to introduce crosslinks or branching, PAS resins that have been polymerized with a small amount of a trihalogen or higher polyhalogen compound to introduce a slight crosslinking or branching, PAS resins modified at the ends and / or molecular chains with functional groups such as carboxyl groups, carboxy metal salts, alkyl groups, alkoxy groups, amino groups, and nitro groups, and PAS resins that have been heat-treated in a non-oxidizing inert gas such as nitrogen. Mixtures of these PAS resins are also acceptable. Among these, PAS resins modified at the ends with amino groups are preferred because they have excellent reactivity with reactive compounds, particularly with the copolymer (B) containing reactive functional groups, and thus facilitate the production of PAS resin compositions with excellent impact resistance and other toughness properties. Furthermore, the PAS resin may be subjected to acid washing, hot water washing, or washing with an organic solvent such as acetone or methyl alcohol to reduce impurities such as sodium atoms, PAS oligomers, sodium chloride, and sodium 4-(N-methyl-chlorophenylamino)butanoate.

[0018] The PAS resin (A) preferably has a melt viscosity of 200 to 3,000 poise as measured using a high-speed flow tester equipped with a die having a diameter of 1 mm and a length of 2 mm under conditions of a measurement temperature of 315°C and a load of 10 kg, since this results in excellent moldability when made into a PAS resin composition and excellent productivity for insulated wires.

[0019] The copolymer (B) constituting the PAS resin composition may be any copolymer that falls within the category of reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymers, and examples of the α,β-unsaturated carboxylic acid alkyl ester residues constituting the copolymer include methyl acrylate residue, ethyl acrylate residue, propyl acrylate residue, hexyl acrylate residue, octyl acrylate residue, glycidyl acrylate residue, methyl methacrylate residue, ethyl methacrylate residue, propyl methacrylate residue, hexyl methacrylate residue, octyl methacrylate residue, glycidyl methacrylate residue, etc. Examples of the reactive functional groups include epoxy groups, maleic anhydride groups, carboxylic acid groups, amino groups, isocyanate groups, etc. The copolymer (B) is particularly suited to producing PAS resin compositions and insulated wires with excellent impact resistance and flexibility. Examples of reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymers include ethylene-α,β-unsaturated carboxylic acid alkyl ester-maleic anhydride copolymer, ethylene-α,β-unsaturated carboxylic acid glycidyl ester copolymer, ethylene-α,β-unsaturated carboxylic acid glycidyl ester-vinyl acetate copolymer, and ethylene-α,β-unsaturated carboxylic acid glycidyl ester-α,β-unsaturated carboxylic acid alkyl ester copolymer. Furthermore, copolymer (B) is preferably a copolymer with a low glass transition temperature, since it provides PAS resin compositions and insulated wires with excellent flexibility and resistance to cold and thermal shocks. If the copolymer (B) does not contain reactive functional groups, the resulting resin composition will have poor toughness and will be a brittle coating or exterior material.

[0020] Commercially available copolymers (B) include maleic anhydride-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymers such as Lotader AX5500 (trade name), BONDINE AX8390, LX4110, and TX8030 manufactured by SK Global Chemical Co., Ltd., and ethylene-α,β-unsaturated carboxylic acid glycidyl ester copolymers such as Lotader AX8700 and AX8750 manufactured by SK Global Chemical Co., Ltd., and Bondfast 7M and 7L (trade names) manufactured by Sumitomo Chemical Co., Ltd.

[0021] The type or copolymerization ratio of copolymer (B) can be determined arbitrarily depending on the shape, thickness, molding temperature, etc. of the intended coating or sheathing material, within the scope of the object of the present invention, and two or more types of copolymer (B) may be mixed and used depending on the object.

[0022] The blending amount of the copolymer (B) is preferably 35 to 80 parts by weight, particularly 40 to 70 parts by weight, per 100 parts by weight of the PAS resin, since this allows for the production of a coating or exterior material with an excellent balance between toughness, such as impact resistance, and heat resistance. If the blending amount of the copolymer (B) is less than 35 parts by weight, the resin composition will have poor toughness, resulting in an electric wire with poor physical properties such as post-processing and thermal shock resistance. On the other hand, if the blending amount exceeds 80 parts by weight, the melt viscosity of the resin composition will be high, making the coating material more susceptible to voids (material defects).

[0023] Furthermore, the fluororesin (C) constituting the PAS resin composition may be any resin that belongs to the category called fluororesin, such as polytetrafluoroethylene (PTFE; relative dielectric constant 2.1), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA; relative dielectric constant 2.1), tetrafluoroethylene-hexafluoropropylene copolymer (FEP; relative dielectric constant 2.1), polychlorotrifluoroethylene (PCTFE; relative dielectric constant 2.6), ethylene-tetrafluoroethylene copolymer (ETFE; relative dielectric constant 2.6), ethylene-chlorotrifluoroethylene copolymer (EC Examples of suitable fluororesins include TFE (dielectric constant 2.6), polyvinylidene fluoride, and polyvinyl fluoride. Fluororesins having a dielectric constant of 3 or less are preferred because they can provide an insulated wire that is excellent in heat resistance and has an excellent balance between dielectric properties, particularly those represented by the dielectric constant, and heat resistance, processability, and mechanical properties. Polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE) are particularly preferred. Two or more of these fluororesins (C) may be mixed and used depending on the intended purpose, such as moldability or viscosity.

[0024] The blending amount of the fluororesin (C) is 10 to 80 parts by weight per 100 parts by weight of the PAS resin (A), and is preferably 20 to 75 parts by weight, since this results in an insulated electric wire with an excellent balance between moldability and dielectric properties. If the blending amount of the fluororesin (C) is less than 10 parts by weight, the resulting electric wire will have poor dielectric properties. On the other hand, if it exceeds 80 parts by weight, the resulting electric wire will have poor moldability as a coating material or exterior material.

[0025] The melt viscosity of the PAS resin composition may be any value that allows melt molding for use as a coating or sheathing material. Among these, a melt viscosity of 2,000 to 25,000 poise, and particularly 3,000 to 20,000 poise, as measured using a high-speed flow tester equipped with a die 1 mm in diameter and 2 mm in length at a temperature of 315°C and a load of 10 kg, is preferred, as this provides excellent moldability, particularly in the manufacture of insulated electric wires. Furthermore, the PAS resin composition preferably has a relative dielectric constant of 3.3 or less, and particularly 3 or less, as measured on a 70 mm x 3 mm x 1 mm thick flat test piece at a temperature of 23°C and a frequency of 2 GHz in accordance with JIS C-2565, in order to provide insulated electric wires with excellent dielectric properties and partial discharge inception voltage. Furthermore, the PAS resin composition preferably has a tensile breaking strain of 8% or more, and particularly 15% or more, as measured in accordance with JIS K 7161, in order to provide insulated electric wires with excellent flexibility.

[0026] The PAS resin composition may contain fillers such as fibrous fillers and non-fibrous fillers. Examples of fibrous fillers include glass fibers; carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers; graphitized fibers; whiskers such as silicon nitride whiskers, basic magnesium sulfate whiskers, barium titanate whiskers, potassium titanate whiskers, silicon carbide whiskers, boron whiskers, and zinc oxide whiskers; metal fibers such as stainless steel fibers; inorganic fibers such as rock wool, zirconia, alumina silica, barium titanate, silicon carbide, alumina, silica, and blast furnace slag; organic fibers such as wholly aromatic polyamide fibers, phenolic resin fibers, and wholly aromatic polyester fibers; and mineral fibers such as wollastonite and magnesium oxysulfate. Examples of non-fibrous fillers include silicates such as wollastonite, zeolite, sericite, kaolin, mica, pyrophyllite, talc, and alumina silicate; oxides such as aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, zinc oxide, and iron oxide; carbonates such as calcium carbonate, magnesium carbonate, and dolomite; sulfates such as calcium sulfate and barium sulfate; nitrides such as silicon nitride, boron nitride, and aluminum nitride; glass flakes, glass beads, etc. The fillers may also be surface-treated with an isocyanate compound, a silane coupling agent, a titanate coupling agent, an epoxy compound, etc.

[0027] Furthermore, the PAS resin composition may contain a silane coupling agent, which will provide it with excellent toughness and other properties. Examples of the silane coupling agent include silane coupling agents consisting of a trialkoxysilane coupling agent having a glycidyl group and / or a trialkoxysilane coupling agent having an amino group. Specific examples include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

[0028] Furthermore, the PAS resin composition may contain a mold release agent to improve mold releasability and appearance when made into an insulated wire. Suitable mold release agents include polyethylene wax, polypropylene wax, and fatty acid amide wax. Commonly available commercial products can be used as the polyethylene wax and polypropylene wax. The fatty acid amide wax is a polycondensate of a higher aliphatic monocarboxylic acid, a polybasic acid, and a diamine. Any wax that falls within this category can be used, such as Light Amide WH-255 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), a polycondensate of stearic acid, sebacic acid, and ethylenediamine.

[0029] The PAS resin composition may be mixed with various additives within the scope of the present invention, for example, one or more conventional additives such as conventionally known plasticizers (e.g., polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, and organic phosphorus compounds), antioxidants, heat stabilizers, ultraviolet inhibitors, and foaming agents. Furthermore, the PAS resin composition may be mixed with one or more thermoplastic resins (e.g., various thermosetting resins, thermoplastic elastomers without reactive functional groups, epoxy resins, cyanate ester resins, phenolic resins, polyimides, silicone resins, polyesters, polyamides, polyphenylene oxides, polycarbonates, polysulfones, polyetherimides, polyethersulfones, polyetherketones, polyetheretherketones, polyamideimides, and polyalkylene oxides).

[0030] The PAS resin composition can be produced by conventionally used melt-kneading methods. Examples include melt-kneading methods using a single-screw or twin-screw extruder, kneader, mill, or Brabender. Melt-kneading using a twin-screw extruder is particularly preferred due to its excellent kneading capacity and productivity. Furthermore, a screw length (L) to screw diameter (D) ratio (L / D) of 30 or greater is desirable because it allows for sufficient kneading and, in some cases, reaction between the PAS resin (A), copolymer (B), and fluororesin (C), thereby enabling the easy production of a PAS resin composition that can provide an insulated electric wire with excellent thermal cycle resistance and toughness. The cylinder temperature in the kneading zone of the extruder is preferably set to 260 to 330°C, and more preferably 260 to 310°C. The peripheral speed of the screw is preferably 50 to 400 mm / sec, and more preferably 150 to 300 mm / sec. The residence time of the molten resin in the extruder is preferably 30 to 100 seconds.

[0031] The conductor constituting the insulated wire of the present invention may be any material that is normally used as a conductor in an electric wire, such as tough pitch copper, pure copper, a copper alloy, aluminum, silver, gold, or any of these conductors plated with a different metal.

[0032] The shape of the conductor constituting the present invention may be any shape that can be called an electric wire. In particular, to improve the coil occupancy rate of the motor, a rectangular cross-section wire is preferred. Among these, a rectangular wire with a short side of 0.8 mm to 5 mm and a long side of 1.4 mm to 7 mm is preferred from the viewpoint of workability when bending the insulated electric wire into a coil. A round wire may also be used, which is advantageous in terms of ease of quality control and cost. Similarly, when forming a coil, the size of the round wire is preferably 0.5 to 5 mm in diameter from the viewpoint of workability.

[0033] The insulated wire of the present invention comprises the conductor coated with the PAS resin composition described above. The thickness of the coating layer is optional as long as the desired dielectric breakdown strength and partial discharge inception voltage are achieved. A thickness of 0.01 to 0.2 mm is preferred, as this provides an insulated wire with excellent conformability, dielectric breakdown strength, partial discharge inception voltage, and gas permeation resistance. The PAS resin composition can be coated using a conventional molding machine, such as an extrusion molding machine, an injection molding machine, a thermal compression molding machine, or a transfer molding machine. Among these, extrusion molding using an extruder is preferred, as it allows continuous coating of conductors with lengths ranging from several hundred meters to several kilometers, making it a molding method with excellent continuous productivity for insulated wires.

[0034] As long as the insulated wire of the present invention has a coating material made of the PAS resin composition on the outer periphery of the conductor, it may be a single layer made of the PAS resin composition or a multilayer including another thermoplastic resin layer, a rubber layer, a thermoplastic elastomer layer, or a thermosetting resin layer. In particular, it may have a water vapor or oxygen barrier layer, a heat-resistant coating layer, etc., and in order to achieve a high breakdown voltage, it is preferable to use a multilayer coating material according to the purpose.

[0035] The insulated wire of the present invention can be used for general purposes. In particular, when the insulated wire is applied to a motor, a generator, a reactor, or the like, the insulated wire can improve motor efficiency and power generation efficiency, thereby contributing to energy saving, miniaturization, and weight reduction of electric vehicles and hybrid vehicles. [Effects of the Invention]

[0036] The insulated wire of the present invention has excellent heat resistance, dielectric breakdown strength, thermal shock cycle resistance, and toughness. Use of the insulated wire can improve the motor efficiency and power generation efficiency of motors, generators, reactors, and the like, and is therefore highly effective in saving energy and reducing the size and weight of electric vehicles and hybrid vehicles. [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a cross-sectional view showing a schematic diagram of an insulated electric wire according to the present invention, including an insulated electric wire 1 having a rectangular cross section and an insulated electric wire 4 having a round cross section. [Example]

[0038] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0039] The polyarylene sulfide resin (A), reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B), fluororesin (C), and conductor used in the examples and comparative examples are shown below.

[0040] <Polyarylene sulfide resin (A)> Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-1)): melt viscosity 493 poise. Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-2)): melt viscosity 1120 poise.

[0041] <Reactive functional group modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B)> Ethylene-α,β-unsaturated butyl carboxylate-glycidyl methacrylate copolymer (B-1) (hereinafter simply referred to as copolymer (B-1)); manufactured by SK global chemical Co., Ltd., (trade name) Lotader AX8700, reactive group: epoxy group, ethylene residue unit: α,β-unsaturated butyl carboxylate residue unit: glycidyl methacrylate residue unit (weight ratio) = 67:25:8. Ethylene-α,β-unsaturated ethyl carboxylate-maleic anhydride copolymer (B-2) (hereinafter simply referred to as copolymer (B-2)); SK global chemical Co., Ltd., (trade name) Bondine AX8390, reactive group: maleic anhydride, ethylene residue unit: α,β-unsaturated ethyl carboxylate residue unit: maleic anhydride residue unit (weight ratio) = 69.7:29:1.3. Ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B'-3) (hereinafter simply referred to as copolymer (B'-3)); manufactured by SK global chemical Co., Ltd., (trade name) LOTRYL 35BA40T, ethylene residue unit:α,β-unsaturated carboxylic acid butyl residue unit (weight ratio) = 65:35; no reactive functional groups.

[0042] <Fluororesin (C)> Polytetrafluoroethylene (C-1) (hereinafter simply referred to as fluororesin (C-1)); manufactured by Kitamura Co., Ltd., (product name) KTL-610. Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) (C-2) (hereinafter simply referred to as fluororesin (C-2)); manufactured by Daikin Industries, Ltd., (trade name) Neoflon AP-201. Tetrafluoroethylene-hexafluoropropylene copolymer (FEP) (C-3) (hereinafter simply referred to as fluororesin (C-3)); manufactured by Daikin Industries, Ltd., (trade name) Neoflon NP-20. Ethylene-tetrafluoroethylene copolymer (ETFE) (C-4) (hereinafter simply referred to as fluororesin (C-4)); manufactured by Daikin Industries, Ltd., (trade name) Neoflon EP-521.

[0043] <conductor> A rectangular conductor approximately 100m long made of tough pitch copper with a rectangular cross section of 3mm long and 2mm short.

[0044] Synthesis Example 1 A 50-liter autoclave equipped with a stirrer was charged with 6214 g of Na2S·2.9H2O and 17,000 g of N-methyl-2-pyrrolidone. The mixture was gradually heated to 205°C while stirring under a nitrogen stream, and 1,355 g of water was distilled off. After cooling to 140°C, 7,168 g of p-dichlorobenzene, 12 g of 3,5-dichloroaniline, and 5,000 g of N-methyl-2-pyrrolidone were added and sealed under a nitrogen stream. The mixture was heated to 225°C over 2 hours and polymerized at 225°C for 2 hours. The mixture was then heated to 250°C over 30 minutes and polymerized at 250°C for another 3 hours. After polymerization, the mixture was cooled to room temperature and the solids were isolated by centrifugation. The solid was washed with hot water at 180°C and dried at 100°C for a day to obtain poly(p-phenylene sulfide).

[0045] The resulting poly(p-phenylene sulfide) was dried at 240°C for 4 hours under reduced pressure using a vacuum dryer to obtain a linear amino group-containing poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-1)). The melt viscosity of PPS (A-1) was 493 poise.

[0046] Synthesis Example 2 A 50-liter autoclave equipped with a stirrer was charged with 6214 g of flake sodium sulfide (Na2S·2.9H2O) and 17,000 g of N-methyl-2-pyrrolidone. The mixture was gradually heated to 205°C while stirring under a nitrogen stream, and 1,355 g of water was distilled off. After cooling to 140°C, 7,278 g of p-dichlorobenzene, 11.7 g of 3,5-dichloroaniline, and 5,000 g of N-methyl-2-pyrrolidone were added and sealed under a nitrogen stream. The mixture was heated to 225°C over 2 hours and polymerized at 225°C for 2 hours. The temperature was then raised to 250°C over 30 minutes and further polymerized at 250°C for 3 hours. After polymerization, the mixture was cooled to room temperature and the polymer was isolated by centrifugation. The solid polymer was repeatedly washed with warm water and dried overnight at 100°C to obtain an amino group-substituted poly(p-phenylene sulfide) with a melt viscosity of 400 poise. The dried amino group-substituted poly(p-phenylene sulfide) was then loaded into a batch rotary kiln-type calciner and cured for 2 hours at 240°C in an air atmosphere to obtain PPS (A-2) with a melt viscosity of 1120 poise and an amino group content of 0.1 mol% relative to the phenyl groups.

[0047] The PAS resin compositions and insulated wires obtained in the examples and comparative examples were evaluated and measured as follows.

[0048] ~Measurement of the relative dielectric constant of PAS resin composition~ The resin composition was injection molded into a flat plate test piece (70 mm × 70 mm × 1 mm thick) using an injection molding machine (SE75, manufactured by Sumitomo Heavy Industries, Ltd.) heated to a cylinder temperature of 320°C and a mold temperature of 60°C, and a test piece (70 mm × 3 mm × 1 mm thick) for measuring the relative dielectric constant was prepared from the flat plate by cutting. The relative dielectric constant and dielectric loss tangent of this test piece were measured using a dielectric constant measuring device (Cavity Resonator, manufactured by AET Corporation) at a measurement temperature of 23°C and a measurement frequency of 2 GHz in accordance with JIS C-2565.

[0049] ~Measurement of partial discharge inception voltage of PAS resin composition~ The obtained resin composition was injection molded into a flat plate test piece (70 mm × 70 mm × 1 mm thick) using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., product name: SE75) heated to a cylinder temperature of 320°C and a mold temperature of 60°C. Electrodes were attached to the thickness direction of this test piece, and the partial discharge inception voltage was measured using a partial discharge inception voltage measuring device in accordance with JEC0401 (1990). A voltage was applied at a constant voltage increase rate (20 V / sec), and the voltage at which a certain charge (100 pC) or more flowed between the electrodes was defined as the partial discharge inception voltage.

[0050] ~Insulated wire coating conformability test~ The insulated wires were cut every 200 mm, bent into a U-shape (R36 mm), and subjected to a thermal shock cycle test at a low temperature of -40°C (30 minutes) and a high temperature of 180°C (30 minutes). The presence or absence of external cracks was confirmed visually or using a magnifying glass every 20 cycles. The number of cycles required for cracking (LD50) to occur in 50% of the 10 test pieces (N=10) was defined as the coating conformability (cycles). Test pieces that had been subjected to 100 or more cycles were deemed to have good coating conformability, while those that had cracks occurring after less than 100 cycles were deemed to have poor coating conformability.

[0051] Example 1 100 parts by weight of the PPS (A-1) obtained in Synthesis Example 1, 50 parts by weight of copolymer (B-1), and 17 parts by weight of fluororesin (C-1) were uniformly mixed in advance and charged into the hopper of a twin-screw extruder (manufactured by The Japan Steel Works, Ltd., product name TEX-25αIII, L / D=55) having three kneading zones. The kneading zone cylinder temperature was heated to 270°C, and the mixture was melt-kneaded at a raw material supply rate of 12 kg / h and a screw rotation speed of 250 rpm (circumferential speed 327 mm / sec). The molten composition flowed out of the die after a residence time of 50 seconds. The molten composition was cooled and then cut to produce pellets of a PPS resin composition.

[0052] Next, a conductor preheated to approximately 320°C in a nitrogen atmosphere in a preheating furnace was introduced into a wire coating machine. The pelletized resin composition obtained in the above example was then added to the hopper. The PPS resin composition was extruded at a cylinder temperature of 320°C, a die temperature of 300°C, and a speed of 20 m / min to form a coating thickness of 75±3 μm. After passing through the die, the extrusion was placed in a preheated 180°C thermostatic oven to remove residual stress. The extrusion was then cooled to below 60°C and wound on a winder to produce an insulated wire. The PPS resin composition and insulated wire were evaluated and evaluated in Table 1. The resulting insulated wire exhibited excellent dielectric properties and partial discharge inception voltage characteristics. It also demonstrated excellent thermal shock resistance and a 280-cycle coating conformity test.

[0053] [Table 1]

[0054] Examples 2 to 15 Pellets of PPS resin compositions were prepared in the same manner as in Example 1, using the blending ratios of polyarylene sulfide (A), copolymer (B), and fluororesin (C) shown in Tables 1 and 2, and then formed into insulated wires. The PPS resin compositions and insulated wires were then evaluated and measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0055] [Table 2]

[0056] Comparative Examples 1 to 5 A pellet-shaped resin composition was prepared in the same manner as in Example 1 using the formulation of polyarylene sulfide (A), copolymer (B.B'), and fluororesin (C) as shown in Table 3, and then an attempt was made to prepare an insulated wire. The PPS resin composition and the insulated wire were then evaluated and measured in the same manner as in Example 1. The results are shown in Table 3.

[0057] The electric wire obtained in Comparative Example 1 was inferior in flexibility due to the use of a copolymer with an unmodified reactive functional group, and cracks occurred in the coating conformability test after bending.

[0058] The electric wire obtained in Comparative Example 2 had a low fluororesin content and a high relative dielectric constant, and therefore the partial discharge inception voltage was 1.9 kV, which was lower than the other Examples.

[0059] The electric wire obtained in Comparative Example 3 had a large amount of fluororesin blended therein and was poor in flexibility, so that cracks occurred in the coating conformability test after bending.

[0060] The electric wire obtained in Comparative Example 4 had a small amount of reactive functional group-modified copolymer blended and was poor in flexibility, and therefore cracks occurred in the coating conformability test after bending.

[0061] The electric wire obtained in Comparative Example 5 had a large amount of reactive functional group-modified copolymer blended, and the crosslinking reaction of copolymer (B) itself increased the viscosity of the resin composition, resulting in a high extrusion torque. As a result, it was not possible to form a wire coating with a thickness of 75 μm, and it was not possible to form a uniform thickness. In Table 3, the coating thickness is shown as "unformable."

[0062] [Table 3] [Industrial Applicability]

[0063] The insulated wire of the present invention has excellent heat resistance, dielectric breakdown strength, thermal shock cycle resistance, and toughness due to the use of a specific PAS resin composition as the insulating layer coating material. This enables motors, generators, reactors, etc. that use this wire to improve motor efficiency and power generation efficiency, contributing to energy savings and reductions in size and weight of electric and hybrid vehicles. [Explanation of symbols]

[0064] 1. Insulated wire with a rectangular cross section 2; conductor 3. Insulating coating material 4. Round cross-section insulated wire 5; conductor 6. Insulating coating material

Claims

1. An insulated wire having a conductor and a covering material covering the conductor, characterized in that the covering material is made of a polyarylene sulfide resin composition containing 100 parts by weight of a polyarylene sulfide resin (A), 35 to 80 parts by weight of a reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B), which is an ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer having an epoxy group and / or a maleic anhydride group, and 10 to 80 parts by weight of a fluororesin (C).

2. An insulated wire as described in claim 1, characterized in that the fluororesin (C) is a fluororesin having a relative dielectric constant of 3 or less.

3. 3. The insulated wire according to claim 1, wherein the fluororesin (C) is at least one fluororesin selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and ethylene-tetrafluoroethylene copolymer.

4. An insulated wire according to any one of claims 1 to 3, characterized in that the coating material has a layer thickness of 0.01 to 0.2 mm.

5. An insulated wire as described in any one of claims 1 to 4, characterized in that the conductor is made of tough pitch copper and / or pure copper and has a rectangular cross section with short sides of 0.8 to 5 mm and long sides of 1.4 to 7 mm.

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