Resin composition

Abstract

To provide an SPS-based resin composition that enables formation of a molded article exhibiting high tensile modulus and superior surface impact resistance.SOLUTION: A resin composition comprising the following components (A) to (C) in the proportions shown below based on the total amount of the components (A) to (C): (A) syndiotactic-structure polystyrene having a weight-average molecular weight of 160,000 to 230,000, in an amount of 42 to 95 mass%; (B) rubber-like elastomer in an amount of 1 to 29 mass%; and (C) polyphenylene ether in an amount of 4 to 29 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a molded article. [Background technology]

[0002] Polystyrene with a syndiotactic structure (hereinafter simply referred to as "syndiotactic polystyrene" or "SPS") can achieve a high degree of crystallinity, and sheets obtained from it have excellent heat and chemical resistance and are used as various molded products. However, molded products obtained from SPS tend to have insufficient impact strength, which limits the range of applications as a material. In response to this, attempts have been made to improve Izod impact strength by blending SPS with a rubber-like elastomer and polyphenylene ether (hereinafter simply referred to as "PPE") (e.g., Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-93153 [Patent Document 2] Japanese Patent Application Publication No. 9-100377 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been difficult to increase the dart impact strength of conventional SPS resin compositions without impairing the tensile modulus of elasticity of the molded article. An object of the present invention is to provide an SPS resin composition that can be used to produce molded articles having a high tensile modulus and excellent dart impact strength. [Means for solving the problem]

[0005] As a result of extensive investigations, the present inventors have found that by using an SPS resin composition comprising a specific blend of SPS having a specific weight-average molecular weight, a rubber-like elastomer, and polyphenylene ether in a specific composition, it is possible to realize molded articles having a high tensile modulus and excellent dart impact strength, and have completed the present invention. According to the present invention, the following resin compositions and the like are provided. 1. A resin composition containing the following components (A) to (C) in the following content ratios relative to the total of components (A) to (C): (A) 42 to 95% by mass of polystyrene having a syndiotactic structure and a weight-average molecular weight of 160,000 to 230,000 (B) Rubber-like elastomer 1 to 29% by mass (C) Polyphenylene ether 4 to 29 mass% 2. The resin composition according to 1, wherein the component (B) is at least one selected from the group consisting of hydrogenated styrene-butadiene-styrene copolymer rubber (SEBS), hydrogenated styrene-ethylene-propylene-styrene copolymer rubber (SEPS), styrene-butadiene-styrene copolymer rubber (SBS), styrene-butadiene copolymer rubber (SBR), ethylene-propylene copolymer rubber (EPR), and modified rubbers thereof. 3. The resin composition according to 1 or 2, wherein the component (B) is one or more selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymers (SEBS) and rubbers modified therefrom. 4. The resin composition according to any one of 1 to 3, wherein component (B) is a combination of 10 to 90 mass% of an elastomer (B-1) containing structural units derived from styrene and 10 to 90 mass% of a maleic acid-modified elastomer (B-2) containing structural units derived from styrene. 5. A resin composition according to any one of 1 to 4, wherein the content of component (A) is 46 to 85 mass%, the content of component (B) is 10 to 29 mass%, and the content of component (C) is 5 to 25 mass%, based on the total of components (A) to (C). 6. The resin composition according to any one of 1 to 5, having a melt flow rate of 6 to 22 g / 10 min. 7. A molded article obtained from the resin composition according to any one of 1 to 6. [Effects of the Invention]

[0006] According to the present invention, there is provided an SPS resin composition which can be used to produce molded articles having a high tensile modulus and excellent dart impact strength. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an outline of a testing device for dart impact strength in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0008] The resin composition of the present invention will be described in detail below. In this specification, "x to y" represents a numerical range of "greater than or equal to x and less than or equal to y." The upper and lower limits of the numerical ranges can be combined in any manner. Furthermore, a combination of two or more of the individual embodiments of the present invention described below is also an embodiment of the present invention. Furthermore, a numerical range of "greater than x" implies "greater than x," and a numerical range of "less than or equal to y" implies "less than y."

[0009] [Resin composition] A resin composition according to one embodiment of the present invention contains the following components (A) to (C) in the following content ratios relative to the total of components (A) to (C). Hereinafter, these components may also be simply referred to as "component (A)," "component (B)," and "component (C)." (A) 42 to 95% by mass of polystyrene having a syndiotactic structure and a weight-average molecular weight of 160,000 to 230,000 (B) Rubber-like elastomer 1 to 29% by mass (C) Polyphenylene ether 4 to 29 mass% Each component of the resin composition will be described below.

[0010] ((A) Polystyrene having a syndiotactic structure and a weight-average molecular weight of 160,000 to 230,000) Syndiotactic polystyrene is a crystalline styrene-based resin with a highly syndiotactic structure. "Syndiotactic" means that the phenyl rings of adjacent styrene units are arranged alternately with respect to the plane formed by the main chain of the polymer block (hereinafter referred to as syndiotacticity).

[0011] Tacticity is measured by nuclear magnetic resonance (NMR) using carbon isotopes. 13 Quantitative identification can be performed using the C-NMR method. 13 By C-NMR, the proportion of consecutive structural units, for example, two consecutive monomer units as a dyad, three consecutive monomer units as a triad, and five consecutive monomer units as a pentad, can be quantified.

[0012] The term "styrene resin having a highly syndiotactic structure" refers to a styrene polymer such as polystyrene, poly(hydrocarbon-substituted styrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), or poly(vinyl benzoate ester), having a syndiotacticity of typically 75 mol % or more, preferably 85 mol % or more in racemic diad (r), or typically 30 mol % or more, preferably 50 mol % or more in racemic pentad (rrrr), hydrogenated polymers or mixtures of these, or copolymers containing these as the main component.

[0013] Examples of poly(hydrocarbon-substituted styrenes) include poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene), poly(vinylnaphthalene), and poly(vinylstyrene). Examples of poly(halogenated styrenes) include poly(chlorostyrene), poly(bromostyrene), and poly(fluorostyrene). Examples of poly(halogenated alkylstyrenes) include poly(chloromethylstyrene). Examples of poly(alkoxystyrenes) include poly(methoxystyrene) and poly(ethoxystyrene).

[0014] Examples of comonomer components of copolymers containing the above structural units include, in addition to the monomers of the above styrene-based polymers, olefin monomers such as ethylene, propylene, butene, hexene, and octene; diene monomers such as butadiene and isoprene; and polar vinyl monomers such as cyclic olefin monomers, cyclic diene monomers, methyl methacrylate, maleic anhydride, and acrylonitrile. Suitable copolymers include a copolymer of styrene and p-methylstyrene, a copolymer of styrene and p-tert-butylstyrene, a copolymer of styrene and divinylbenzene, and the like, with a copolymer of styrene and p-methylstyrene being preferred.

[0015] Among syndiotactic polystyrenes, one or more selected from polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), and copolymers of styrene and p-methylstyrene are preferred, one or more selected from polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), and copolymers of styrene and p-methylstyrene are more preferred, polystyrene and copolymers of styrene and p-methylstyrene are even more preferred, and polystyrene is most preferred.

[0016] The weight average molecular weight of component (A) is 160,000 to 230,000. Within this range, it is possible to produce molded articles that have a high tensile modulus and excellent dart impact strength. It has been believed that the higher the weight-average molecular weight of SPS, the better the impact resistance of the resulting molded article, and high-molecular-weight SPS has been used for this purpose (see, for example, Patent Documents 1 and 2). However, the inventors' investigations have revealed that if the weight-average molecular weight of SPS is too high, the dispersion of component (B) (the rubber-like elastomer) in the resin composition becomes too fine, thereby worsening the impact resistance (surface impact strength) of the molded article. Therefore, in the present invention, by specifying the weight-average molecular weight of SPS, it is possible to achieve high levels of both tensile modulus and surface impact strength. Furthermore, the present invention can improve the fluidity of the resin composition, thereby enabling the production of larger molded articles or molded articles with complex shapes.

[0017] The weight average molecular weight of component (A) may be, for example, 165,000 or more, or 170,000 or more, and may be, for example, 220,000 or less, 210,000 or less, or 200,000 or less.

[0018] The weight average molecular weight of component (A) is a value measured by gel permeation chromatography at 130° C. using 1,2,4-trichlorobenzene as a solvent, and converted using a calibration curve of standard polystyrene.

[0019] The melt flow rate (MFR) of component (A) is preferably 6 g / 10 min or more, more preferably 8 g / 10 min or more, and even more preferably 10 g / 10 min or more, and is preferably 22 g / 10 min or less, more preferably 20 g / 10 min or less, and even more preferably 18 g / 10 min or less. The MFR of component (A) is measured under conditions of a temperature of 300°C and a load of 1.2 kg.

[0020] Component (A) can be produced by a known method, for example, by polymerizing a styrene-based monomer in an inert hydrocarbon solvent or in the absence of a solvent using a condensation product of a titanium compound, water, and trialkylaluminum as a catalyst.

[0021] In the resin composition according to one embodiment of the present invention, the content of component (A) relative to the total of components (A) to (C) (when two or more types are contained, the total amount of these) is 42 to 95 mass %. In the resin composition according to one embodiment of the present invention, the content of component (A) relative to the total of components (A) to (C) is, for example, 45% by mass or more, 46% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, or 65% by mass or more. In the resin composition according to one embodiment of the present invention, the content of component (A) relative to the total of components (A) to (C) is, for example, 90% by mass or less, 85% by mass or less, or 80% by mass or less. In the resin composition according to one aspect of the present invention, the content of component (A) relative to the total of components (A) to (C) is, for example, 46 to 85 mass %, or 55 to 80 mass %.

[0022] ((B) Rubber-like elastomer) The resin composition according to one aspect of the present invention contains a rubber-like elastic material (component (B)), which can improve the toughness of the molded article and increase the dart impact strength. Various materials can be used as component (B), but preferably it is an elastomer containing structural units derived from styrene, such as at least one selected from the group consisting of styrene-diene block copolymers, hydrogenated styrene-diene block copolymers, styrene-diene random copolymers, hydrogenated styrene-diene random copolymers, and styrene-olefin random copolymers. Examples of dienes copolymerized with styrene include butadiene and isoprene, and examples of olefins copolymerized with styrene include ethylene, propylene, and butylene. Chemically modified elastomers, such as those modified with maleic acid (e.g., maleic anhydride), can also be used.

[0023] Component (B) is more preferably styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), styrene-butadiene random copolymer, hydrogenated styrene-butadiene random copolymer, styrene-ethylene-propylene random copolymer, and styrene-ethylene The rubber composition is at least one selected from the group consisting of styrene-butadiene block copolymers (SBR), hydrogenated styrene-butadiene block copolymers (SEB), styrene-butadiene-styrene block copolymers (SBS), hydrogenated styrene-butadiene-styrene block copolymers (SEBS), styrene-isoprene block copolymers (SIR), hydrogenated styrene-isoprene block copolymers (SEP), styrene-isoprene-styrene block copolymers (SIS), hydrogenated styrene-isoprene-styrene block copolymers (SEPS), and ethylene-propylene copolymer rubber (EPR). In one embodiment, component (B) is at least one selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymer (SEBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), styrene-butadiene-styrene block copolymer (SBS), styrene-butadiene block copolymer (SBR), and ethylene-propylene copolymer rubber (EPR). In one embodiment, component (B) is a hydrogenated styrene-butadiene-styrene block copolymer (SEBS). Furthermore, the above materials may also be chemically modified, for example, with maleic acid (for example, maleic anhydride).

[0024] The mass ratio of the structural units derived from styrene to the total of the structural units derived from diene, hydrogenated diene, and olefin constituting component (B) [(styrene) / (diene, hydrogenated diene, olefin)] is preferably 20 / 80 to 70 / 30, and may be 25 / 75 to 65 / 35, or 30 / 70 to 60 / 40. The styrene content of the rubbery elastomer is preferably in the range of 25 to 60% by mass, and may be 25 to 45%. By achieving such a mass ratio, compatibility with component (A) can be further enhanced, and toughness can be improved while maintaining heat resistance and dimensional stability at high temperatures.

[0025] As the component (B), the above compounds can be used alone or in combination of two or more. When two or more types are used in combination, for example, an elastomer containing structural units derived from styrene (hereinafter also referred to as component (B-1)) and a maleic acid-modified elastomer containing structural units derived from styrene (hereinafter also referred to as component (B-2)) are used in combination. An example of component (B-1) is a hydrogenated styrene-butadiene-styrene block copolymer (SEBS), and an example of component (B-2) is a maleic acid-modified hydrogenated styrene-butadiene-styrene block copolymer (SEBS). The mixing ratio of these may be, for example, 10 to 90 mass % (for example, 50 to 90 mass %) of component (B-1) and 10 to 90 mass % (for example, 10 to 50 mass %) of component (B-2).

[0026] The melt flow rate (MFR) of component (B) is preferably 50 g / 10 min or less, more preferably 10 g / 10 min or less, and even more preferably 5 g / 10 min or less. The MFR of component (B) is measured in accordance with JIS K7210-1:2014 (ISO1133-1:2011) at a temperature of 230°C and a load of 2.16 kg.

[0027] In the resin composition according to one embodiment of the present invention, the content of component (B) (the total amount when two or more types are included) relative to the total of components (A) to (C) is 1 to 29 mass %. Within this range, it is possible to increase the dart impact strength while maintaining a high tensile modulus of elasticity of the molded article. In the resin composition according to one embodiment of the present invention, the content of component (B) relative to the total of components (A) to (C) is, for example, 3 mass% or more, 5 mass% or more, 10 mass% or more, or 15 mass% or more. In the resin composition according to one embodiment of the present invention, the content of component (B) relative to the total of components (A) to (C) is, for example, 27 mass% or less, or 25 mass% or less. In the resin composition according to one aspect of the present invention, the content of component (B) relative to the total of components (A) to (C) is, for example, 5 to 29 mass %, 10 to 29 mass %, or 15 to 25 mass %.

[0028] ((C) Polyphenylene ether) By adding a certain amount or more of polyphenylene ether (component (C)) to the resin composition according to one embodiment of the present invention, it is possible to improve the dart impact strength of the resulting molded article while maintaining a high tensile modulus.

[0029] Examples of polyphenylene ethers include poly(2,3-dimethyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-chloromethyl-1,4-phenylene ether), poly(2-methyl-6-hydroxyethyl-1,4-phenylene ether), poly(2-methyl-6-n-butyl-1,4-phenylene ether), poly(2-ethyl-6-isopropyl-1,4-phenylene ether), poly(2-ethyl-6-n-propyl-1,4-phenylene ether), poly(2,3,6-trimethyl-1,4-phenylene ether), poly[2-(4'-methylphenyl)-1,4-phenylene ether], poly(2-bromo-6-phenyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2-phenyl-1,4-furan), and the like. poly(2-chloro-1,4-phenylene ether), poly(2-methyl-1,4-phenylene ether), poly(2-chloro-6-ethyl-1,4-phenylene ether), poly(2-chloro-6-bromo-1,4-phenylene ether), poly(2,6-di-n-propyl-1,4-phenylene ether), poly(2-methyl-6-isopropyl-1,4-phenylene ether), poly(2-chloro-6-methyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2,6-dibromo-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), and poly(2,6-dimethyl-1,4-phenylene ether). Also usable are copolymers with various phenolic compounds, and graft copolymers and block copolymers with vinyl aromatic compounds such as polystyrene.

[0030] In the resin composition according to one embodiment of the present invention, the content of component (C) (when two or more types are included, the total amount of components (A) to (C)) is 4 to 29 mass %. Within this range, it is possible to increase the dart impact strength while maintaining a high tensile modulus of elasticity of the molded article. In the resin composition according to one embodiment of the present invention, the content of component (C) relative to the total of components (A) to (C) is, for example, 5% by mass or more, or 6% by mass or more. In the resin composition according to one embodiment of the present invention, the content of component (C) relative to the total of components (A) to (C) is, for example, 25% by mass or less, or 20% by mass or less. In the resin composition according to one aspect of the present invention, the content of component (C) relative to the total of components (A) to (C) is, for example, 5 to 25 mass %, or 5 to 20 mass %.

[0031] (Additives, other resins (D), etc.) The resin composition according to one embodiment of the present invention may or may not contain various additives and resin components other than the above-described components (A) to (C) (e.g., thermoplastic resins) within the scope of not impairing the effects of the present invention. Hereinafter, these components will also be referred to simply as "component (D)." Note that, by definition, any component that corresponds to any of the above-described components (A) to (C) will be treated as any of the components (A) to (C).

[0032] The additives that can be blended include, for example, antioxidants, nucleating agents, plasticizers, mold release agents, flame retardants, flame retardant assistants, pigments, carbon black, antistatic agents, and the like.

[0033] The nucleating agent can be arbitrarily selected from known nucleating agents such as metal salts of carboxylic acids such as aluminum di(pt-butylbenzoate), metal salts of phosphoric acids such as sodium methylenebis(2,4-di-t-butylphenol) acid phosphate, talc, phthalocyanine derivatives, etc. These nucleating agents can be used singly or in combination of two or more.

[0034] The plasticizer can be arbitrarily selected from known plasticizers such as polyethylene glycol, polyamide oligomer, ethylene bisstearamide, phthalate ester, polystyrene oligomer, polyethylene wax, mineral oil, silicone oil, etc. These plasticizers can be used alone or in combination of two or more.

[0035] The release agent can be arbitrarily selected from known agents such as polyethylene wax, silicone oil, long-chain carboxylic acid, long-chain carboxylate, etc. These release agents can be used alone or in combination of two or more.

[0036] The antioxidant can be selected from known antioxidants such as phosphorus-based, phenol-based, sulfur-based, etc. These antioxidants can be used alone or in combination of two or more.

[0037] The flame retardant can be arbitrarily selected from known compounds such as brominated polymers including brominated polystyrene, brominated syndiotactic polystyrene, and brominated polyphenylene ether, and brominated aromatic compounds such as brominated diphenylalkane and brominated diphenyl ether. The flame retardant synergist can be arbitrarily selected from antimony compounds including antimony trioxide and others, and can be used singly or in combination of two or more.

[0038] The thermoplastic resin can be arbitrarily selected from known thermoplastic resins such as linear high-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, block polypropylene, random polypropylene, polybutene, 1,2-polybutadiene, cyclic polyolefin, and poly-4-methylpentene, polystyrene-based resins such as polystyrene, HIPS, ABS, and AS, polyester-based resins such as polycarbonate, polyethylene terephthalate, and polybutylene terephthalate, polyamide-based resins such as polyamide 6 and polyamide 6,6, polyphenylene ether, and polyphenylene sulfide. The thermoplastic resins can be used singly or in combination of two or more.

[0039] When the resin composition according to an embodiment of the present invention contains component (D), the content thereof is, for example, 1% by mass or more, 3% by mass or more, or 5% by mass or more. There is no particular upper limit, but the content is, for example, 40% by mass or less, or 20% by mass or less. In one embodiment, the resin composition does not include component (D).

[0040] (Resin composition) The resin composition according to one embodiment of the present invention preferably has a melt flow rate (MFR) of 5 to 50 g / 10 min. Within this range, the resin composition has excellent fluidity while maintaining mechanical properties, and it is possible to produce larger molded articles or molded articles with complex shapes. As described above, by employing component (A) having a specific weight-average molecular weight, a styrene-based resin composition having the above-mentioned MFR can be obtained. The MFR is more preferably 7.5 to 40 g / 10 min, and further preferably 10 to 30 g / 10 min. The MFR of the resin composition is measured by the method described in the Examples.

[0041] The resin composition according to one embodiment of the present invention may contain, for example, 80% by mass or more, 85% by mass or more, 87% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.9% by mass or more, or 100% by mass of Component (A), component (B), and component (C), or Component (A), component (B), component (C), and component (D) (e.g., additives) may be.

[0042] (Molded products, applications, etc.) The resin composition according to one embodiment of the present invention can easily and inexpensively provide molded articles that are not only excellent in physical properties such as elasticity and impact resistance but also excellent in chemical resistance. Therefore, the resin composition can be effectively used to produce, for example, various molded articles by injection molding; sheets, films, etc. by extrusion molding; containers, trays, etc. by extrusion molding and thermoforming; uniaxially or biaxially stretched films, sheets, etc. by extrusion molding and stretching; fibrous molded articles by spinning; and various molded articles by foaming. [Example]

[0043] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0044] [Ingredients used] The materials used in the following examples and comparative examples are as follows. ((A) Polystyrene having a syndiotactic structure and a weight-average molecular weight of 160,000 to 230,000) SPS1: Syndiotactic polystyrene, manufactured by Idemitsu Kosan Co., Ltd., weight average molecular weight: 180,000, MFR: 13 g / 10 min (300°C, load 1.2 kg)

[0045] ((A') Polystyrene not corresponding to component (A)) SPS2: Syndiotactic polystyrene, manufactured by Idemitsu Kosan Co., Ltd., weight average molecular weight: 140,000, MFR: 30g / 10min (300°C, load 1.2kg) The weight average molecular weights of the above components (A) and (A') are values ​​measured by gel permeation chromatography at 130°C using 1,2,4-trichlorobenzene as a solvent. 13 C-NMR measurements confirmed that SPS1 to SPS2 were all polystyrenes with a syndiotactic structure.

[0046] ((B) Rubber-like elastomer) SEBS1: Hydrogenated styrene-butadiene-styrene block copolymer, Kuraray Co., Ltd. "Septon 8006", styrene content 33% by mass SEBS2: Maleic acid-modified hydrogenated styrene-butadiene-styrene block copolymer, "Tuftec M1913" manufactured by Asahi Kasei Corporation, styrene content 30% by mass, MFR: 5.0 g / 10 min (temperature 230°C, load 2.16 kg)

[0047] ((C) Polyphenylene ether) PPE1: Polyphenylene ether, "Iupiace PX-100L" manufactured by Mitsubishi Engineering Plastics Corporation

[0048] Example 1 (1) Production and evaluation of resin compositions The components shown in Table 1 were used in the composition (mass%) shown in Table 1. Furthermore, 0.5 parts by weight of an organic metal phosphate (NA-21, manufactured by ADEKA Corporation) as a nucleating agent, 0.1 parts by weight of (2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite (PEP-36, manufactured by ADEKA Corporation) as an antioxidant, and 0.1 parts by weight of pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate (AO60, manufactured by ADEKA Corporation) were added. The mixture was dry-blended in a Henschel mixer and then melt-kneaded in a twin-screw extruder with a screw diameter of 37 mm to obtain pellets (resin composition). The resulting resin composition was evaluated as follows. The results are shown in Table 1. The composition (mass%) in Table 1 indicates the proportion of each component relative to the total of components (A) to (C).

[0049] (MFR) Measurements were taken at a temperature of 300°C and a load of 2.16 kg in accordance with JISK7210-1:2014 (ISO1133-1:2011). (Tensile modulus (MPa)) Measurements were taken in accordance with JIS7161-2:2014 (ISO527-2:2012).

[0050] (surface impact strength) The obtained resin composition was injection molded under the following conditions, and test pieces were prepared from the molded articles. The 50% fracture energy was calculated by a DuPont impact test to evaluate the dart impact strength. (Injection molding conditions and test piece conditions) Molding machine: Toshiba injection molding machine "EC180-SX" Cylinder temperature: 290-290-280-270 Mold temperature: Fixed side set at 85°C (actual temperature 79°C) Mold temperature: Movable side set at 85°C (actual temperature 79°C) Injection speed: 70mm / sec Test piece (DuPont test piece) size: 100mm x 80mm x 2.2mm The test piece was a 100mm x 80mm portion cut out from the gate side of a molded product measuring 100mm x 420mm x 2.2mm. (Measurement conditions) Evaluation tester: Mize tester (automatic DuPont type drop impact tester) Distance between fulcrums: 25.4mm Support R1: 40.0 mm Fulcrum R2: 14.6mm Load capacity: 1kg or 2kg Strike diameter: 12.7mm An overview of the test equipment is shown in Figure 1.

[0051] Example 2, Comparative Examples 1 to 5 Pellets (resin compositions) were produced and evaluated in the same manner as in Example 1, except that the composition of the components shown in Table 1 was changed as shown in Table 1. The results are shown in Table 1.

[0052]

Table 1

Claims

1. A resin composition comprising the following components (A) to (C) in the following content ratios relative to the total of components (A) to (C): (A) 42 to 95% by mass of polystyrene having a syndiotactic structure and a weight-average molecular weight of 160,000 to 230,000 (B) Rubber-like elastic material: 1 to 29% by mass (C) Polyphenylene ether 4 to 29 mass%

2. The resin composition according to claim 1, wherein the component (B) is one or more selected from the group consisting of hydrogenated styrene-butadiene-styrene copolymer rubber (SEBS), hydrogenated styrene-ethylene-propylene-styrene copolymer rubber (SEPS), styrene-butadiene-styrene copolymer rubber (SBS), styrene-butadiene copolymer rubber (SBR), ethylene-propylene copolymer rubber (EPR), and rubbers modified therefrom.

3. The resin composition according to claim 1 or 2, wherein the component (B) is at least one selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymers (SEBS) and rubbers modified therefrom.

4. The resin composition according to any one of claims 1 to 3, wherein, as the component (B), 10 to 90% by mass of an elastomer (B-1) containing a structural unit derived from styrene and 10 to 90% by mass of a maleic acid-modified elastomer (B-2) containing a structural unit derived from styrene are used in combination.

5. The resin composition according to any one of claims 1 to 4, wherein the content of the component (A) is 46 to 85 mass%, the content of the component (B) is 10 to 29 mass%, and the content of the component (C) is 5 to 25 mass%, based on the total of the components (A) to (C).

6. The resin composition according to any one of claims 1 to 5, having a melt flow rate of 6 to 22 g / 10 min.

7. A molded article obtained from the resin composition according to any one of claims 1 to 6.

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