Polyarylene sulfide resin composition

Abstract

To provide a polyarylene sulfide resin composition which is excellent in dielectric characteristics and a partial discharge start voltage, and adhesion and coatability, and accordingly is suitable for applications of a coating material and resin piping, without impairing heat resistance inherent to a polyarylene sulfide resin.SOLUTION: A polyarylene sulfide resin composition contains, with respect to 100 pts.wt. of a polyarylene sulfide resin (A), 5 to 45 pts.wt. of a saponified ethylene-vinyl acetate copolymer (B), and 10 to 45 pts.wt. of a polyethylene resin (C) having a melt tension at 260°C of 100 mN or more and a molecular weight distribution determined by a GPC method of 9.0 or more, and has a melt viscosity under the conditions of 290°C and a load of 10 Kg of 2,000 to 8,000 poise.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 and resin pipes with excellent dielectric withstand voltage. [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 not only long-term heat resistance but also 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). According to formula (1), in order for an electric wire to have a high partial discharge inception voltage, it is required that the relative dielectric constant be low relative to the resin composition that is the insulating coating material. 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, electric wires used for such applications are continuously formed by extrusion molding, followed by bending, and the end faces of the wire are electrically connected by spot welding to form a single long wire. The resin composition used as the insulating coating is also required to have flexibility during bending of the electric wire and adhesion to the conductor.

[0004] The resin composition used for such an insulating coating or the insulated wire produced using the same contains polyarylene sulfide (I) and tetrafluoroethylene / hexafluoropropylene copolymer (II), and the fluororesin (II) has an average particle size of 0.1 μm or more and less than 2.5 μm, and the fluororesin (II) has a carbonyl group at the end of its main chain having 10 carbon atoms. 6 An insulated wire has been proposed in which the fluororesin (II) has 80 or more particles per wire, and the melting point of the fluororesin (II) is 230° C. to 350° C. (see, for example, Patent Document 1).

[0005] Also proposed is an insulated wire that includes a conductor and an insulating layer disposed around the conductor, the insulating layer having an inner layer and an outer layer, the inner layer being formed from a halogen-free resin composition containing a base polymer (A) that includes a thermoplastic resin (a1) that has an aromatic ring in the main chain and does not contain nitrogen atoms, and the outer layer being formed from a crosslinked product obtained by crosslinking a halogen-free flame-retardant resin composition that includes a base polymer (B) that includes a polyolefin component and a halogen-free flame retardant (see, for example, Patent Document 2).

[0006] Furthermore, in order to further improve insulation performance, there is a demand for not only coating materials but also resin pipes with excellent dielectric strength. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5737464 [Patent Document 2] Patent No. 6816419 Summary of the Invention [Problem to be solved by the invention]

[0008] In the insulated wire of Patent Document 1, in order to improve the partial discharge inception voltage, a fluororesin with a low relative dielectric constant is dispersed in a polyarylene sulfide matrix to reduce the dielectric constant of the resin composition. However, while an improvement in the partial discharge inception voltage is achieved, the resin has poor adhesion and bonding properties, which results in gaps between the coating layer and the conductor, lowering the partial discharge inception voltage and making it difficult to maintain insulation over the long term.

[0009] Similarly, the insulated wire of Patent Document 2 also has a problem with adhesion between the conductor and the inner layer of the coating material.

[0010] Therefore, there is a demand for a material that not only has excellent heat resistance, insulation properties, and mechanical properties, but also has properties that do not cause problems with the coating even when the insulating coating layer is thin when forming electric wires, etc., or when production speeds are high, and that can be processed without causing cracks when bending is performed after forming the extrusion-molded product, as well as a material that has excellent insulation withstand voltage properties and can be used as a coating material for bus bar parts or for hollow piping (so-called tubes). [Means for solving the problem]

[0011] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a polyarylene sulfide resin composition containing a polyarylene sulfide resin, a saponified ethylene-vinyl acetate copolymer, and a specific polyethylene resin has a low relative dielectric constant while ensuring adhesion to conductors, is compatible with relatively high-speed wire coating molding, and also has excellent toughness such as tensile breaking strength and impact resistance, making it suitable for applications such as resin piping, and have thereby completed the present invention.

[0012] Specifically, the present invention relates to a PAS resin composition characterized by comprising 100 parts by weight of a polyarylene sulfide resin (hereinafter sometimes simply referred to as PAS resin) (A), 5 to 45 parts by weight of a saponified ethylene-vinyl acetate copolymer (hereinafter sometimes simply referred to as saponified EVA) (B), and 10 to 45 parts by weight of a polyethylene resin (C) having a melt tension of 100 mN or more at 260°C and a molecular weight distribution determined by GPC of 9.0 or more, and having a melt viscosity of 2000 to 8000 poise at 290°C under a load of 10 kg.

[0013] The present invention will be described in detail below.

[0014] 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.

[0015] 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 an aprotic 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'-dichlorodiphenyl.

[0016] Examples of PAS resin (A) include linear PAS resins, PAS resins that have been heat-treated in oxygen to introduce crosslinking 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 at the molecular chain 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 molecular chain with amino groups are preferred because they exhibit excellent interaction with saponified EVA containing polar groups, as well as excellent reactivity with reactive compounds, particularly polymers containing reactive functional groups that may be blended, thereby facilitating 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.

[0017] The PAS resin (A) preferably has a melt viscosity of 200 to 3,000 poises 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. For resin compositions to be used in extrusion molding processes such as molding plastic piping and coating materials, a melt viscosity of 500 to 2,000 poises is preferred.

[0018] The saponified EVA (B) constituting the PAS resin composition of the present invention is a copolymer having vinyl alcohol structural units, which are the saponification product of ethylene units and vinyl acetate units (and in some cases containing unsaponified vinyl acetate units). Therefore, despite its low dielectric constant, the hydroxyl groups in the vinyl alcohol units have high polarity, giving it excellent dispersibility in PAS resins. In addition, it exhibits adhesive and cohesive properties through interaction with metal oxides present on the surface of metal components, such as copper oxide on the surface of copper and copper alloys.

[0019] Such saponified EVA (B) can be obtained by saponifying EVA, an ethylene-vinyl acetate copolymer. Among these, those with a high degree of saponification and a large amount of hydroxyl groups are preferred, as they enhance the polar effect derived from the hydroxyl groups. The degree of saponification of vinyl acetate unit components, calculated in accordance with JIS K7192 (1999), is preferably 60% by weight or more, more preferably 80% by weight or more, and may even be a fully saponified product of 100% by weight. Furthermore, the ethylene content is preferably 65 mol% to 90 mol%, as this will enable the provision of a PAS resin composition with excellent flexibility and toughness.

[0020] Examples of the saponified EVA (B) include commercially available products such as (trade name) Mersene H6051 (manufactured by Tosoh Corporation) and (trade name) Mersene H6960 (manufactured by Tosoh Corporation). Also, saponified EVA having any degree of saponification may be prepared by heat treating EVA with an aqueous sodium hydroxide solution, and examples of EVA include (trade name) Ultrathene 751 (vinyl acetate content: 28%) (manufactured by Tosoh Corporation) and (trade name) Ultrathene 750 (vinyl acetate content: 32%) (manufactured by Tosoh Corporation).

[0021] The saponified EVA (B) preferably has a melt mass-flow rate of 100 g / 10 min or less as measured in accordance with JIS K6924-1 (under conditions of 190°C and a load of 2160 g) in order to provide a PAS resin composition that has an excellent balance between melt viscosity and melt tension and is easy to mold at high speed and achieve thin wall thickness. The saponified EVA (B) may be one type alone or two or more types may be combined for the purpose of adjusting the amount of hydroxyl groups or viscosity, within the scope of the object of the present invention.

[0022] The amount of saponified EVA (B) to be blended is 5 to 45 parts by weight per 100 parts by weight of PAS resin (A), preferably 10 to 35 parts by weight, as this provides excellent adhesion to metal surfaces and heat and chemical resistance. If the amount of saponified EVA to be blended is less than 5 parts by weight, the resulting resin composition will have poor adhesion to metal surfaces, resulting in gaps when formed into an integrated metal part and insufficient insulation. On the other hand, if the amount exceeds 45 parts by weight, the resulting resin composition will have poor heat and oil resistance.

[0023] The polyethylene resin (C) constituting the PAS resin composition of the present invention is a polyethylene resin having a melt tension at 260°C of 100 mN or more and a molecular weight distribution (hereinafter sometimes referred to as Mw) of 9.0 or more, which is the ratio of weight-average molecular weight (hereinafter sometimes referred to as Mw) to number-average molecular weight (hereinafter sometimes referred to as Mn). In order to obtain a PAS resin composition with particularly excellent extrusion moldability, it is preferably a polyethylene resin having a melt tension of 120 mN or more and an Mw / Mn of 10 or more. Here, if the melt tension is less than 100 mN or the Mw / Mn is less than 9.0, the resulting resin composition will have a low shear rate dependency of the melt viscosity and will be inferior in melt moldability and high-speed moldability.

[0024] The polyethylene resin (C) may be any polyethylene resin, as long as it falls within the category of polyethylene resins. Examples include ethylene homopolymers obtained by low-pressure or medium-pressure processes, ethylene-α-olefin copolymers (high-density polyethylene, low-density polyethylene (hereinafter sometimes referred to as LLDPE)), relatively new long-chain branched LLDPE resins, and high-pressure low-density polyethylene (hereinafter sometimes referred to as LDPE). Among these, LDPE is preferred because of its long-chain branched structure, high melt tension, and wide molecular weight distribution. Furthermore, commercially available LDPE may be heat-adjusted by melt-kneading at 130°C to 220°C in the presence of oxygen using a twin-screw extruder or Banbury mixer, for example, to adjust the branching number, melt tension, molecular weight distribution, etc. LDPE is characterized by its high melt tension. LDPE that has been heat-adjusted as described above exhibits high melt tension regardless of the mass flow rate (MFR). It can be prepared, for example, by the methods described in Japanese Patent Nos. 6047953 and 6115130.

[0025] The melt tension can be measured by known methods. For example, the melt tension of the polyethylene resin (C) and the PAS resin composition can be measured in a thermostatic chamber set at 23°C, at 260°C, by filling an 18 g sample into a capillary viscometer (manufactured by Toyo Seiki Seisakusho, product name: Capilograph) with a barrel diameter of 9.55 mm and equipped with a die having a length of 8 mm, a diameter of 2.095 mm, and an inlet angle of 90°, setting the piston descending speed to 10 mm / min, and the draw ratio to 4.7, and measuring the load (mN) required for take-up as the melt tension. The Mw, Mn, and Mw / Mn of the polyethylene resin (C) can be measured, for example, by gel permeation chromatography (GPC). The Mw / Mn of the polyethylene resin (C) in the PAS resin composition can be determined by dissolving the PAS resin composition in an aprotic nonpolar solvent such as toluene or xylene with heating and measuring the melt tension.

[0026] The amount of polyethylene resin (C) is 10 to 45 parts by weight per 100 parts by weight of PAS resin (A). It is preferably 10 to 35 parts by weight, more preferably 15 to 35 parts by weight, because this results in a PAS resin composition with an excellent balance between moldability and low dielectric properties. If the amount of polyethylene resin is less than 10 parts by weight, the resulting resin composition will have insufficient melt tension and poor extrusion moldability. On the other hand, if the amount is more than 45 parts by weight, the resulting resin composition will have an excessively high melt tension, which can cause moldability problems. The non-stickiness of the polyethylene resin can impair the adhesion of saponified EVA to metal parts, which can lead to other problems.

[0027] The PAS resin composition of the present invention, which contains a PAS resin (A), a saponified EVA (B), and a polyethylene resin (C), has a melt viscosity of 2000 to 8000 poise, preferably 2000 to 4000 poise, because it provides excellent extrusion moldability for resin piping, coating materials, etc. If the melt viscosity is less than 2000 poise, the melt viscosity is low and the extrusion moldability for insulated wires, hollow piping, etc. is poor. On the other hand, if the melt viscosity exceeds 8000 poise, the melt viscosity is too high, making it difficult to increase the production rate (extrusion rate). The melt viscosity can be measured, for example, using a high-performance flow tester equipped with a die having a diameter of 1 mm and a length of 2 mm, at a measurement temperature of 290°C and a load of 10 kg.

[0028] In order to obtain a PAS resin composition with excellent dielectric properties and partial discharge inception voltage, it is preferable that the dielectric constant be 3.2 or less, particularly 2.9 or less, as measured on a 70 mm x 3 mm x 1 mm thick strip test piece at a measurement temperature of 23°C and a measurement frequency of 2 GHz in accordance with JIS C-2565. Furthermore, in order to obtain a PAS resin composition with excellent flexibility, it is preferable that the tensile breaking strain be 8% or more, particularly 15% or more, as measured in accordance with JIS K 7161.

[0029] Furthermore, the PAS resin composition of the present invention may contain fillers such as fibrous fillers and non-fibrous fillers within the scope of the present invention. Examples of fibrous fillers include glass 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; 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.

[0030] 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.

[0031] Furthermore, the PAS resin composition of the present invention may contain a release agent to improve the appearance of molded articles. Suitable 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.

[0032] 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 optionally having 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).

[0033] 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 (L1) to screw diameter (D1) ratio (L1 / D1) of 30 or greater is desirable because it ensures sufficient kneading of the PAS resin (A), saponified EVA (B), and polyethylene resin (C), and, if necessary, reaction with other additives, thereby enabling the easy production of a PAS resin composition with excellent adhesion, thermal cycle resistance, toughness, and melt processability. Furthermore, the cylinder temperature of the kneading zone of the extruder is preferably set to 260 to 310°C, and more preferably 260 to 300°C. Furthermore, 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 120 seconds.

[0034] The PAS resin composition of the present invention can be molded into any shape using an extrusion molding machine, blow molding machine, transfer molding machine, compression molding machine, etc., and can be used as various products and parts such as electrical and electronic parts, automotive parts, etc. In particular, due to its excellent electrical insulation properties, dielectric properties, and adhesion, it can be used as a coating material for insulated wires, an insulating hollow pipe for bundling wires, etc., and an insulating joint. Among these, when molding into an insulated wire, extrusion molding is preferred because of its excellent continuous productivity. Also, when making a hollow pipe, injection blow molding, extrusion molding, and blow molding are preferred.

Effects of the Invention

[0035] The PAS resin composition of the present invention has a low relative dielectric constant while having high adhesion without impairing the heat resistance, dielectric breakdown strength, etc. of the PAS resin. Therefore, it can be suitably used for applications such as electrical and electronic parts or automotive parts, especially for coating materials for insulated wires, bus bars for inverters, hollow molded products such as insulating pipe parts and joints, etc. At the same time, motors, generators, or reactors using insulated wires made of the PAS resin composition of the present invention can improve motor efficiency and power generation efficiency, and are expected to contribute to energy savings, downsizing, and weight reduction of electric vehicles and hybrid vehicles. [[ID=​​​​​​​​​​​​​​​​​​Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-3)): manufactured by Toray Industries, Inc., (trade name) Torelina M2888, melt viscosity 790 poise.

[0039] <Saponified EVA (B)> Saponified EVA (B-1): Tosoh Corporation, trade name Mersen H6960 (vinyl acetate content before saponification treatment: 19 mol %, degree of saponification of vinyl acetate component: 90 wt %, MFR: 40 g / 10 min). Saponified EVA (B-2): Tosoh Corporation, trade name Mersen H6051K (vinyl acetate content before saponification treatment: 28 mol %, degree of saponification of vinyl acetate component: 96 wt %, MFR: 7 g / 10 min). Saponified EVA (B-3): Tosoh Corporation, trade name Mersen H6410M (vinyl acetate content before saponification: 18 mol %, degree of saponification of vinyl acetate component: 20 wt %, MFR: 15 g / 10 min). Saponified EVA (B-4): Tosoh Corporation, trade name Mersen H6822X (vinyl acetate content before saponification treatment: 6 mol %, degree of saponification of vinyl acetate component: 80 wt %, MFR: 214 g / 10 min).

[0040] <EVA(B’)> EVA (B'-5) manufactured by Tosoh Corporation, (trade name) Ultrathene 751 (vinyl acetate content 28 mol%, no saponification treatment, MFR 8 g / 10 min).

[0041] <Polyethylene resin (C)> The preparation was carried out based on the method described in Japanese Patent No. 6047953. The kneading machine used was a counter-rotating twin-screw extruder (manufactured by Toyo Seiki Seisakusho, trade name: Labo Plastomill 2D25S type) with intermeshing screws. The melt mass flow rate was 1.6 g / 10 min and the density was 919 kg / m 3The LDPE (manufactured by Tosoh Corporation, trade name Petrothene 360; melt tension 75 mN) was melt-kneaded under the conditions of a kneading temperature of 160°C, a discharge rate of 1.7 kg / hour, a screw rotation speed of 60 rpm, an oxygen concentration of 21%, and a filling rate of 80%, extruded into a strand shape, and obtained as LDPE pellets (C-1) using a strand cutter (manufactured by Seiwa Iron Works Co., Ltd.). The screw used was a multi-flight type with reverse lead (2S25R type). The Mw / Mn value was 10.0 and the melt tension was 172 mN. LDPE (C'-2): Commercially available LDPE (manufactured by Tosoh Corporation, trade name Petrothene 360; melt tension 75 mN, melt mass-flow rate 1.6 g / 10 min, density 919 kg / m 3 The Mw / Mn value was 8.1.

[0042] 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).

[0043] The resulting poly(p-phenylene sulfide) was dried at 240°C for 4 hours under reduced pressure using a vacuum dryer to obtain PPS (A-1), a linear amino group-containing poly(p-phenylene sulfide) with an amino group content of 0.1 mol% relative to the phenyl group. The melt viscosity of PPS (A-1) was 493 poise.

[0044] 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.

[0045] The PAS resin compositions obtained in the examples and comparative examples were evaluated and measured by the methods shown below.

[0046] (1) Evaluation of adhesion of PAS resin composition Pre-dried pellets of the PAS resin composition were placed in the hopper of an in-line screw-type electric injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., product name SE-75S), and a flat plate (length 70 mm × width 70 mm × thickness 1.0 mm) was obtained under conditions of a cylinder temperature of 290°C and a mold temperature of 80°C.

[0047] Next, a separately prepared copper sheet (145 mm long x 145 mm wide x 0.1 mm thick, made of pure copper) and two injection-molded flat plates of the PAS resin composition were placed one on top of the other in a mold frame for hot compression molding (external dimensions: 200 mm long x 200 mm wide x 0.8 mm thick, internal dimensions: punched frame with 150 mm long x 150 mm wide), and together with a release film (made of polyimide), hot compression press molding was performed using a hydraulic press (50 ton automatic press, manufactured by Shinto Kogyo Co., Ltd.) to obtain a laminated flat plate of copper and PAS resin composition (150 mm long x 150 mm wide x 0.7 mm thick).

[0048] The laminated plate was cut into a width of 15 mm, and four points in the center were used as test pieces for evaluating adhesion.

[0049] (Adhesion measurement) Using a tensile tester (Tensilon RTE-1210, manufactured by ORIENTEC), the strength was measured when peeling the copper sheet from the PAS resin layer at 20 mm / sec, and the average value of four tests was taken as the adhesion (unit: N / 15 mm). A value of 8.0 N / 15 mm or higher was considered to have excellent adhesion.

[0050] (2) Relative permittivity measurement A test piece (70 mm x 3 mm x 1 mm thick) for measuring the relative permittivity was prepared by cutting from the injection-molded flat plate obtained by the same method as in (1) above. The relative permittivity and dielectric loss tangent of this test piece were measured at a measurement frequency of 2 GHz using a relative permittivity measuring device (manufactured by AET Corporation, (product name) Cavity Resonator) in accordance with JIS C-2565. In this case, a material with a relative permittivity of 3.0 or less was considered to have a certain partial discharge inception voltage, and in particular, a material with a relative permittivity of 2.9 or less was considered to be excellent.

[0051] (3) Measurement of tensile properties Test pieces for evaluating tensile properties (tensile strength, tensile modulus, and tensile breaking strain) were prepared by injection molding using a pre-dried PAS resin composition in an injection molding machine (SE75S, manufactured by Sumitomo Heavy Industries, Ltd.) heated to a cylinder temperature of 310°C and a mold temperature of 60°C. Flexural properties were measured in accordance with JIS K7171. PAS resin compositions with a tensile breaking strain of 10% or more were considered to have good flexibility, and those with a tensile breaking strain of 15% or more were considered to be excellent.

[0052] (4) Melt viscosity measurement The melt viscosity was measured using a high-temperature 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 290°C and a load of 10 kg. At this time, PAS resin compositions with a melt viscosity of 2000 poise or more and 8000 poise or less were judged to have good extrusion moldability.

[0053] (5) Melt tension measurement The melt tension was measured by known methods. In a thermostatic chamber set to 23°C, the temperature was set to 260°C, and 18 g of sample was filled into a capillary viscometer (Toyo Seiki Seisakusho, (trade name) Capilograph) with a barrel diameter of 9.55 mm and equipped with a die having a length of 8 mm, a diameter of 2.095 mm, and an inlet angle of 90°. The piston descending speed was set to 10 mm / min, and the draw ratio was set to 4.7, and the load (mN) required for take-up was measured as the melt tension.

[0054] (6) Measurement of Mw and Mn The Mw, Mn, and Mw / Mn of LDPE were measured using gel permeation chromatography (GPC). After weighing a measurement sample, the sample was added to a solvent of HPLC-grade 1,2,4-trichlorobenzene (Wako Pure Chemical Industries, Ltd.) containing 0.1% BHT (Wako Pure Chemical Industries, Ltd.) as an antioxidant, and the mixture was shaken at 140°C for 1 hour to dissolve the sample solution. The measurement system used was a Tosoh Corporation (trade name) HLC-8121 GPC / HT, and three connected TSKgel GMHHR-H(20)HT columns (Tosoh Corporation, 7.8 mm inner diameter, 30 cm length) were used as separation columns. The mobile phase consisted of HPLC-grade 1,2,4-trichlorobenzene (Wako Pure Chemical Industries, Ltd.) supplemented with 0.05% BHT (Wako Pure Chemical Industries, Ltd.) as an antioxidant. The mobile phase was maintained at 140 °C and moved through the separation column at a flow rate of 1.0 ml / min. 0.3 ml of sample solution adjusted to a concentration of 1.0 mg / ml was injected into the mobile phase, and the separated sample components were detected using a differential refractometer. A fifth-order approximation curve prepared using standard polystyrene (Tosoh Corporation) was used as a calibration curve to calculate Mn, Mw, and Mw / Mn.

[0055] (7) Judgment Those that were excellent in adhesion, relative dielectric constant, flexibility and extrusion moldability were judged as ◯, and those that were poor in any one of these were judged as ×.

[0056] Example 1 100 parts by weight of the PPS (A-1) obtained in Synthesis Example 1, 8 parts by weight of saponified EVA (B-1), and 30 parts by weight of polyethylene resin (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, L1 / D1=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.

[0057] The obtained PAS resin composition was measured and evaluated by the above-mentioned methods, and the results are shown in Table 1.

[0058] Examples 2 to 9 Pellets of PAS resin compositions were prepared in the same manner as in Example 1, except that the blending amounts of PAS (A), saponified EVA (B), and polyethylene resin (C) were set as shown in Table 1.

[0059] The physical properties were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0060] [Table 1]

[0061] Comparative Examples 1 to 6 A pellet-shaped resin composition was prepared in the same manner as in Example 1, except that the blending amounts of PAS (A), saponified EVA (B), EVA (B'), polyethylene resin (C), and polyethylene resin (C') were set as shown in Table 2.

[0062] The physical properties were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0063] [Table 2]

[0064] Example 10 A pellet-shaped PAS resin composition was prepared in the same manner as in Example 2, except that PPS (A-3) was used instead of PPS (A-1).

[0065] The physical properties were evaluated in the same manner as in Example 1, and the results were adhesion=11.1 N / 15 mm, relative dielectric constant=2.79, tensile breaking strain=20%, viscosity=3100 poise, and the evaluation was good. [Industrial Applicability]

[0066] The PAS resin composition of the present invention has a low dielectric constant and good adhesion to conductors without impairing the heat resistance, dielectric breakdown strength, etc., inherent to PAS resins, and is therefore suitable for applications such as electric / electronic components or automobile components, particularly applications such as hollow molded products such as coating materials for insulated electric wires, inverter bus bars, and insulating piping components and joints. Motors, generators, or 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 polyarylene sulfide resin composition comprising 100 parts by weight of a polyarylene sulfide resin (A), 5 to 45 parts by weight of a saponified ethylene-vinyl acetate copolymer (B), and 10 to 45 parts by weight of a polyethylene resin (C) having a melt tension of 100 mN or more at 260°C and a molecular weight distribution of 9.0 or more as determined by a GPC method, and having a melt viscosity of 2000 to 8000 poise at 290°C under a load of 10 kg.

2. The polyarylene sulfide resin composition according to claim 1, wherein the saponified ethylene-vinyl acetate copolymer (B) is a saponified ethylene-vinyl acetate copolymer having a degree of saponification of the vinyl acetate component calculated in accordance with JIS K7192 of 60% by weight or more.

3. The polyarylene sulfide resin composition according to claim 1, wherein the saponified ethylene-vinyl acetate copolymer (B) is a saponified ethylene-vinyl acetate copolymer having an ethylene unit content of 65 mol% or more and 90 mol% or less.

4. 2. The polyarylene sulfide resin composition according to claim 1, wherein the polyethylene resin (C) is a high-pressure low-density polyethylene.

5. 2. The polyarylene sulfide resin composition according to claim 1, wherein the polyethylene resin (C) is a heat-melt-treated, high-pressure low-density polyethylene.

6. An insulating coating material, which is an extrusion molded product of the polyarylene sulfide resin composition according to claim 1.

7. A resin pipe which is an extrusion molded article of the polyarylene sulfide resin composition according to claim 1.

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