Polyarylene sulfide resin composition

Abstract

To provide a polyarylene sulfide resin composition which is excellent in dielectric characteristics and a partial discharge inception voltage and is also excellent in toughness such as tensile breaking strength and impact resistance without impairing heat resistance that a polyarylene sulfide resin originally has.SOLUTION: A polyarylene sulfide resin composition 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) having a relative dielectric constant of 3.0 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyarylene sulfide resin composition that is excellent in dielectric properties and partial discharge inception voltage, and also in toughness such as tensile break strength and impact resistance, without impairing the heat resistance inherent to polyarylene sulfide resins, and relates to a polyarylene sulfide resin composition that is particularly useful for applications such as insulated wires produced by extrusion molding, coating materials with excellent dielectric withstand voltage, and resin piping. [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 electric vehicles, such as 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, the dielectric properties of the control cable proposed in Patent Document 1 were not satisfactory. Also, in the proposal of Patent Document 2, an insulated wire using such a resin composition has a relatively high relative dielectric constant of the resin composition, which results in a relatively high partial discharge inception voltage, and 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 output of the motor.

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

[0009] Therefore, an object of the present invention is to provide a polyarylene sulfide resin composition which maintains the heat resistance, chemical resistance, dielectric breakdown strength and low dielectric constant inherent to polyarylene sulfide resins and does not generate cracks even after bending after molding, thermal shock cycles or molding. [Means for solving the problem]

[0010] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that a polyarylene sulfide resin composition containing a polyarylene sulfide resin, a specific ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer, and a specific fluororesin has heat resistance, chemical resistance, dielectric breakdown strength, and a low dielectric constant, and can be free from cracks even after thermal shock cycles or molding, thereby completing the present invention.

[0011] That is, the present invention relates to a PAS resin composition characterized by 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) having a relative dielectric constant of 3.0 or less.

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

[0013] The PAS resin (A) constituting the PAS resin composition of the present invention 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 that is particularly excellent in heat resistance and strength properties.

[0014] 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.

[0015] 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.

[0016] 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 will result in excellent moldability when made into a PAS resin composition.

[0017] The copolymer (B) constituting the PAS resin composition of the present invention may be any copolymer that belongs to the category of reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymers. Examples of the α,β-unsaturated carboxylic acid alkyl ester residue 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 group include epoxy group, maleic anhydride group, carboxylic acid group, amino group, isocyanate group, etc. The copolymer (B) is a reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer, which provides a PAS resin composition with excellent impact resistance and flexibility. Examples of such 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, the copolymer (B) is preferably a copolymer with a low glass transition temperature, which provides a PAS resin composition with excellent flexibility and resistance to cold and thermal shock. If the copolymer (B) does not have a reactive functional group, the resulting resin composition will have poor toughness.

[0018] 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.

[0019] The type or copolymerization ratio of copolymer (B) can be determined arbitrarily depending on the desired product shape, resin layer thickness, molding temperature, compounding composition, etc., without departing from the object of the present invention. Two or more types of copolymer (B) may be mixed and used depending on the purpose.

[0020] The blending amount of 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, because this allows for a PAS resin composition that has an excellent balance between toughness such as impact resistance and the heat resistance of the resin composition. If the blending amount of copolymer (B) is less than 35 parts by weight, the resin composition will have poor toughness, and when made into an insulated wire, physical properties such as post-processing and cold and thermal shock resistance will be poor. On the other hand, if the blending amount exceeds 80 parts by weight, the melt viscosity of the resin composition will be high, making it more likely to produce voids (material defects) during molding.

[0021] The fluororesin (C) constituting the PAS resin composition of the present invention may be any resin that belongs to the category of fluororesins having a relative dielectric constant of 3.0 or less, 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), and ethylene-tetrafluoroethylene copolymer (ETFE; relative dielectric constant 2.6). Examples of suitable fluororesins include ethylene-chlorotrifluoroethylene copolymer (ECTFE; dielectric constant 2.6), and the like. Among these, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (RIFE) are preferred, as they provide PAS resin compositions that are excellent in heat resistance and exhibit a particularly good balance between dielectric properties, such as dielectric constant, and heat resistance, processability, and mechanical properties. Two or more of these fluororesins (C) may be mixed depending on the intended purpose, such as moldability or viscosity. If the fluororesin has a dielectric constant exceeding 3.0, the resulting resin composition will have a high dielectric constant and poor electrical resistance.

[0022] The 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 a PAS resin composition with an excellent balance between moldability and dielectric properties. If the amount of fluororesin (C) is less than 10 parts by weight, the resulting resin composition will have poor dielectric properties. On the other hand, if it exceeds 80 parts by weight, the resulting resin composition will have poor moldability.

[0023] The melt viscosity of the PAS resin composition of the present invention may be any as long as it allows for melt molding. In particular, since the composition has excellent moldability for hollow molded articles such as coating materials for electric wires and the like and piping for insulation withstand voltage, it is preferable that the melt viscosity be 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 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.

[0024] Furthermore, the PAS resin composition of the present invention has excellent dielectric properties and partial discharge inception voltage, and is particularly suitable as a material for excellent performance coating materials, piping, and other electronic and electrical components. Therefore, it is preferable that the PAS resin composition has a relative dielectric constant of 3.3 or less, and particularly 3.0 or less, as measured on a 70 mm × 3 mm × 1 mm thick plate test piece at a measurement temperature of 23°C and a measurement frequency of 2 GHz in accordance with JIS C-2565.

[0025] Furthermore, since the PAS resin composition of the present invention has excellent flexibility, particularly when used as a covering material for electric wires and the like, or as a hollow product, it is preferable that the tensile breaking strain measured in accordance with JIS K 7161 is 8% or more, particularly 15% or more.

[0026] Furthermore, the PAS resin composition of the present invention 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 of the present invention may contain a silane coupling agent, which will provide 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 of the present invention may contain a mold release agent to improve mold releasability and appearance when forming a molded product. 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 within this category can be used, such as Light Amide WH-255 (manufactured by Kyoeisha Chemical Co., Ltd.), a polycondensate of stearic acid, sebacic acid, and ethylenediamine.

[0029] The PAS resin composition of the present invention may be mixed with various additives within the scope of the present invention, and may contain 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 contain 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] Conventional hot melt kneading methods can be used to produce the PAS resin composition of the present invention. Examples include hot melt kneading methods using a single-screw or twin-screw extruder, kneader, mill, Brabender, or the like. 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 to ensure 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 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 PAS resin composition of the present invention can be molded into any shape using an injection molding machine, extrusion molding machine, blow molding machine, transfer molding machine, compression molding machine, etc., and can be used to make various products and parts such as electric / electronic components and automobile parts. In particular, because of its excellent electrical insulation and dielectric properties, it can be used to make coating materials for insulated electric wires, insulated hollow pipes for bundling electric wires, and insulated joints. Of these, extrusion molding is preferred for molding into insulated electric wires because of its excellent continuous productivity. In addition, injection blow molding, extrusion molding, and blow molding are preferred for making hollow pipes. [Effects of the Invention]

[0032] The PAS resin composition of the present invention has a low dielectric constant without compromising the heat resistance, dielectric breakdown strength, and other properties inherent to PAS resins, and also has high toughness that allows for thermal shock cycle resistance and post-molding processing.It can be suitably used for applications such as electrical and electronic parts or automotive parts, particularly for applications such as insulating wire coating materials, and hollow molded products such as insulating piping parts and joints.In addition, motors, generators, and reactors made from insulated wires using the PAS resin composition of the present invention can improve motor efficiency and power generation efficiency, and are expected to contribute to energy savings, miniaturization, and weight reduction of electric and hybrid vehicles. [Example]

[0033] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0034] The polyarylene sulfide (A), reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B), and fluororesin (C) used in the examples and comparative examples are shown below.

[0035] <Polyarylene sulfide (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.

[0036] <Reactive functional group modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B)> Ethylene-α,β-unsaturated carboxylic acid butyl ester-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 carboxylic acid alkyl ester residue unit: glycidyl methacrylate residue unit (weight ratio) = 67:25:8. Ethylene-α,β-unsaturated carboxylic acid ethyl ester-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 carboxylic acid alkyl ester residue unit: maleic anhydride residue unit (weight ratio) = 69.7:29:1.3. Ethylene-α,β-unsaturated carboxylic acid butyl ester copolymer (B'-3): SK global chemical Co., Ltd., (product name) LOTRYL 35BA40T, ethylene residue unit:α,β-unsaturated carboxylic acid alkyl ester residue unit (weight ratio) = 65:35, no reactive functional groups.

[0037] <Fluororesin (C)> Polytetrafluoroethylene (C-1) (hereinafter simply referred to as fluororesin (C-1)); manufactured by Kitamura Co., Ltd., (trade name) KTL-610, dielectric constant 2.1. 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, dielectric constant 2.1. Tetrafluoroethylene-hexafluoropropylene copolymer (FEP) (C-3) (hereinafter simply referred to as fluororesin (C-3)); manufactured by Daikin Industries, Ltd., (trade name) Neoflon NP-20, dielectric constant 2.1. Ethylene-tetrafluoroethylene copolymer (ETFE) (C-4) (hereinafter simply referred to as fluororesin (C-4)); manufactured by Daikin Industries, Ltd., (trade name) Neoflon EP-521, dielectric constant 2.6. Polyvinylidene fluoride (PVDF) (C'-5) (hereinafter simply referred to as fluororesin (C'-5)); manufactured by Kuraray Co., Ltd., (trade name) KF Polymer #1000, dielectric constant 7.7.

[0038] 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).

[0039] The resulting poly(p-phenylene sulfide) was dried at 240°C for 4 hours under reduced pressure using a vacuum dryer to obtain linear amino group-containing poly(p-phenylene sulfide) PPS (A-1). The melt viscosity of PPS (A-1) was 493 poise.

[0040] 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.

[0041] The PAS resin compositions obtained in the examples and comparative examples were evaluated by the methods described below.

[0042] ~Melt viscosity measurement~ The melt viscosity was measured using a high-performance flow tester (Shimadzu Corporation, product name CFT-500) equipped with a die having a diameter of 1 mm and a length of 2 mm, under the conditions of a measurement temperature of 315°C and a load of 10 kg. At this time, PAS resin compositions with a melt viscosity of 2000 poise or more and 25000 poise or less were judged to have good moldability, and those with a melt viscosity of 3000 poise or more and 20000 poise or less were judged to have excellent moldability.

[0043] ~Measurement of tensile properties~ The resulting resin composition was injection molded 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 to prepare test specimens for evaluating tensile properties (tensile strength, tensile modulus, and tensile elongation at break). The tensile property tests were conducted in accordance with JIS K7161. PAS resin compositions with a tensile break strain of 8% or more were considered to have good flexibility for use as wire coating materials, and those with a tensile break strain of 15% or more were considered to be excellent.

[0044] ~Measurement of relative permittivity~ The resulting resin composition was injection molded into flat plate test pieces (70 mm x 70 mm x 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. Test pieces for dielectric constant measurement (70 mm x 3 mm x 1 mm thick) were then cut from the flat plates. The dielectric constant and dielectric loss tangent of these test pieces were measured at a measurement temperature of 23°C and a measurement frequency of 2 GHz using a dielectric constant measuring device (manufactured by AET Corporation, product name: Cavity Resonator) in accordance with JIS C-2565. A material with a dielectric constant of 3.3 or less was considered to have a certain partial discharge inception voltage, and a material with a dielectric constant of 3.0 or less was considered to be excellent.

[0045] 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 10 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 PAS resin composition flowed out of the die after a residence time of 50 seconds. The molten PAS resin composition was cooled and then cut into pellets to produce a PAS resin composition.

[0046] The obtained PAS resin composition was measured and evaluated by the above-mentioned methods, and the results are shown in Table 1.

[0047] [Table 1]

[0048] Examples 2 to 15 Pellets of PAS resin compositions were prepared in the same manner as in Example 1, with the blending ratios of PAS (A), copolymer (B), and fluororesin (C) set as shown in Tables 1 and 2.

[0049] The physical properties were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 1 and 2.

[0050] [Table 2]

[0051] Comparative Examples 1 to 6 Pellets of resin compositions were prepared in the same manner as in Example 1, with the blending ratios of PAS (A), copolymers (B, B') and fluororesins (C, C') set as shown in Table 3.

[0052] The physical properties were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0053] The resin composition using copolymer (B'-3) of Comparative Example 1 has a small tensile break strain, and is therefore likely to crack when bent after molding into an insulated wire. Furthermore, cracks may occur due to differences in linear expansion caused by thermal shock cycles. The resin composition using fluororesin (C'-5) of Comparative Example 2 and the resin composition of Comparative Example 3 have high relative dielectric constants, low partial discharge inception voltages, and are therefore likely to induce dielectric breakdown. The resin composition of Comparative Example 4 is also likely to crack when bent after molding into an insulated wire. Furthermore, cracks may occur due to differences in linear expansion caused by thermal shock cycles. The resin composition of Comparative Example 5 is also likely to crack when bent after molding into an insulated wire. Furthermore, cracks may occur due to differences in linear expansion caused by thermal shock cycles. The resin composition of Comparative Example 6 has a high melt shear viscosity, and may not be suitable for molding.

[0054] [Table 3] [Industrial Applicability]

[0055] The PAS resin composition of the present invention has a low dielectric constant without compromising the heat resistance, dielectric breakdown strength, and other properties inherent to PAS resins, and also has high toughness that allows for thermal shock cycle resistance and post-molding processing, making it suitable for applications such as electric and electronic parts or automotive parts, particularly for applications such as hollow molded products such as coating materials for insulated electric wires, insulated piping parts, and joints. Motors, generators, and reactors using these can improve motor efficiency and power generation efficiency, contributing to energy savings and reductions in size and weight of electric and hybrid vehicles.

Claims

1. A tough polyarylene sulfide resin composition comprising, per 100 parts by weight of a polyarylene sulfide resin (A), 40 to 70 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 20 to 75 parts by weight of a fluororesin (C) having a relative dielectric constant of 3.0 or less.

2. 2. The tough polyarylene sulfide resin composition according to claim 1, wherein the reactive functional group-modified ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B) is an ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer having a maleic anhydride group.

3. 3. The tough polyarylene sulfide resin composition 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. 4. The tough polyarylene sulfide resin composition according to claim 1, wherein the melt viscosity of the tough polyarylene sulfide resin composition is 3,000 to 20,000 poises, as measured using a high-temperature 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.

5. The tough polyarylene sulfide resin composition according to any one of claims 1 to 4, characterized in that the relative dielectric constant measured using a flat plate test piece of 70 mm x 3 mm x 1 mm thickness at a measurement temperature of 23°C and a measurement frequency of 2 GHz in accordance with JIS C-2565 is 3.0 or less.

6. An insulating coating material, which is an extrusion molded product of the tough polyarylene sulfide resin composition according to any one of claims 1 to 5.

7. 6. A pipe for dielectric withstand voltage use, which is a hollow molded article of the tough polyarylene sulfide resin composition according to claim 1.

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