Resin composition, pellet, and molded article

Abstract

The invention provides a resin composition, and a pellet and a molded article formed from the resin composition. A resin composition containing a polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less, a thermoplastic resin (X) having a lower SP value than the polybutylene terephthalate resin, and carbon fibers (wherein the SP value is a solubility parameter), the content of the carbon fibers in the resin composition being 5-30 mass%, and the content of the thermoplastic resin (X) being less than the solubility parameter. The mass ratio of the polybutylene terephthalate resin (PBT) having an intrinsic viscosity of 0.80 dL / g or less to the thermoplastic resin (X), i.e., X / PBT, is greater than 0.1 and less than 1.0.

Description

Technical Field

[0001] The present invention relates to a resin composition, a pellet and a molded product, and particularly to a resin composition containing a polybutylene terephthalate resin. Background Art

[0002] Polybutylene terephthalate resin is used in a variety of applications such as electrical / electronic / OA equipment parts and machine parts because of its excellent mechanical properties, electrical properties, heat resistance, and the like.

[0003] Polybutylene terephthalate has excellent properties, but on the other hand, due to its high resistivity, it is easy to be charged, which may cause various obstacles caused by static electricity. For example, if a resin molded product is charged with static electricity, dust and dirt will adhere to the surface, resulting in a decrease in appearance and a decrease in product value. In particular, in the use of electrical / electronic / OA equipment parts, the charging of the resin molded product becomes a cause of malfunction and sometimes causes major functional problems, so a resin material that can prevent charging and exert excellent conductivity is required.

[0004] On the other hand, in electrical / electronic / OA equipment, the electronic components located inside the resin molded product as the housing generate electromagnetic waves. Therefore, in order to prevent the electromagnetic waves from leaking to the outside of the equipment, the following operation is usually performed: a metal film is formed on the surface of the housing as an electromagnetic wave shielding layer by plating, evaporation, etc. In addition, in recent years, due to the simplification of product manufacturing processes and the diversification of product designs, it is required to make the resin material of the housing itself have the electromagnetic wave shielding property, that is, a resin composition with excellent electromagnetic wave shielding property.

[0005] As a resin composition having excellent electromagnetic wave shielding properties, Patent Document 1 discloses a thermoplastic resin composition, characterized in that it is a thermoplastic resin composition comprising 50 to 95% by weight of a polycarbonate resin (A1) and / or a polyester resin (A2) and 50 to 5% by weight of graphite (B), and the composition is formulated with a polycarbonate resin (A1) and / or a polyester resin (A2) and graphite (B) having a water content of less than 0.2%.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2008-163270 Summary of the invention

[0009] Problems to be solved by the invention

[0010] Here, in the above-mentioned Patent Document 1, only the method of using polycarbonate resin as a resin component is specifically studied. However, it would be beneficial if there were a resin composition having excellent electromagnetic wave shielding properties utilizing the performance of polybutylene terephthalate resin. In addition, for a resin composition containing polybutylene terephthalate resin, fluidity is sometimes required. Furthermore, in recent years, from the viewpoint of effective utilization of resources, the use of recycled resins has been actively studied. However, if recycled resins are used, the performance is generally inferior to that of virgin resins.

[0011] The present invention aims to solve the above-mentioned problems, and its purpose is to provide a resin composition having excellent electromagnetic wave shielding properties and fluidity, and a pellet and a molded product formed from the resin composition. Furthermore, it is also aimed to provide a resin composition using recycled resin and having performance comparable to that when using virgin resin.

[0012] Methods for solving problems

[0013] Based on the above problems, the present inventors have conducted research and found that the above problems can be solved by using a polybutylene terephthalate resin having a low intrinsic viscosity and mixing it with a thermoplastic resin (e.g., a polystyrene resin) having a lower SP value than the polybutylene terephthalate resin, and further adjusting the mixing ratio of the polybutylene terephthalate resin and the thermoplastic resin (e.g., a polystyrene resin) having a lower SP value than the polybutylene terephthalate resin. Furthermore, the present inventors have found that by using a recycled polystyrene resin as the polystyrene resin, a resin composition having performance comparable to that of a virgin resin can be provided.

[0014] Specifically, the above-mentioned problems were solved by the following means.

[0015] <1> A resin composition comprising a polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less, a thermoplastic resin (X) having an SP value lower than that of the polybutylene terephthalate resin, and carbon fibers (wherein the SP value is a solubility parameter), wherein the content of the carbon fibers in the resin composition is 5 to 30% by mass, and the mass ratio of the polybutylene terephthalate resin (PBT) having an intrinsic viscosity of 0.80 dL / g or less to the thermoplastic resin (X), i.e., X / PBT, is greater than 0.1 and less than 1.0.

[0016] <2> The resin composition according to <1>, wherein the thermoplastic resin having an SP value lower than that of the polybutylene terephthalate resin comprises a polystyrene-based resin.

[0017] <3> The resin composition according to <1> or <2>, wherein the thermoplastic resin (X) includes a recycled product.

[0018] <4> The resin composition according to any one of <1> to <3>, further comprising a compatibilizer.

[0019] <5> The resin composition according to <4>, wherein the compatibilizer comprises a polycarbonate resin.

[0020] <6> The resin composition according to <4> or <5>, wherein the compatibilizer comprises a recycled polycarbonate resin.

[0021] <7> The resin composition according to any one of <1> to <6>, which is used for electromagnetic wave shielding.

[0022] <8> The resin composition according to any one of <1> to <7>, wherein the thermoplastic resin (X) having an SP value lower than that of the polybutylene terephthalate resin comprises a polystyrene-based resin, the resin composition further comprises a compatibilizer, the compatibilizer comprises a polycarbonate resin, and the resin composition is used for electromagnetic wave shielding.

[0023] <9> The resin composition according to <8>, wherein the thermoplastic resin (X) having an SP value lower than that of the polybutylene terephthalate resin comprises a recycled product.

[0024] <10> A resin composition comprising a polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less, a polystyrene resin and carbon fibers, wherein the mass ratio of the polybutylene terephthalate resin (PBT) having an intrinsic viscosity of 0.80 dL / g or less to the polystyrene resin, i.e., PS / PBT, is greater than 0.1 and less than 1.0.

[0025] <11> The resin composition according to <10>, wherein the polystyrene-based resin includes a recycled product.

[0026] <12> Pellets formed from the resin composition according to any one of <1> to <11>.

[0027] <13> A molded article formed from the resin composition according to any one of <1> to <11>.

[0028] <14> A molded article formed from the pellets described in <12>.

[0029] Effects of the Invention

[0030] According to the present invention, a resin composition having excellent electromagnetic wave shielding properties and fluidity, and pellets and molded products formed from the resin composition can be provided. In particular, a resin composition using recycled resin and having performance comparable to that of virgin resin can be provided. DETAILED DESCRIPTION

[0031] Hereinafter, a mode for implementing the present invention (hereinafter, simply referred to as "this embodiment") will be described in detail. It should be noted that the following this embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment.

[0032] In addition, in this specification, "to" is used to mean that the numerical values ​​described before and after it are included as a lower limit and an upper limit.

[0033] In this specification, various physical property values ​​and characteristic values ​​are those at 23°C unless otherwise specified.

[0034] In this specification, the weight average molecular weight and the number average molecular weight are polystyrene-equivalent values ​​measured by GPC (gel permeation chromatography) unless otherwise specified.

[0035] When the measurement methods and the like described in the standards shown in this specification differ depending on the year, unless otherwise specified, the standards as of January 1, 2022 are used.

[0036] The resin composition of the present embodiment is characterized in that it comprises a polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less, a thermoplastic resin (X) having an SP value lower than that of the polybutylene terephthalate resin, and carbon fibers (wherein the SP value is a solubility parameter), the content of the carbon fibers in the resin composition being 5 to 30% by mass, and the mass ratio of the thermoplastic resin (X) to the polybutylene terephthalate resin (PBT) having an intrinsic viscosity of 0.80 dL / g or less, i.e., X / PBT, being greater than 0.1 and less than 1.0. By setting such a configuration, a resin composition having excellent electromagnetic wave shielding and fluidity can be obtained. Furthermore, a resin composition having excellent mechanical strengths including impact resistance and heat resistance can be obtained.

[0037] By adding carbon fiber to polybutylene terephthalate resin, electromagnetic wave shielding can be achieved to some extent. In the present embodiment, it can be further speculated that by using polybutylene terephthalate resin with low inherent viscosity, the breakage of carbon fiber can be effectively suppressed during melt mixing and injection molding, so that the length of carbon fiber in the molded product becomes relatively long, and electromagnetic wave shielding can be improved. Furthermore, in the present embodiment, it is speculated that by making the mass ratio of thermoplastic resin (X) (such as polystyrene resin (PS)) having an SP value lower than that of polybutylene terephthalate resin and the above-mentioned polybutylene terephthalate resin (PBT) greater than 0.1 and less than 1.0, the viscosity in the molten state can be further reduced, and the electromagnetic wave shielding can be further improved.

[0038] In addition, by using a polybutylene terephthalate resin having a low intrinsic viscosity and a thermoplastic resin (X) (for example, a polystyrene resin (PS)) at a predetermined ratio, a resin composition having excellent fluidity and dimensional stability can be obtained.

[0039] <Polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less>

[0040] The resin composition of the present embodiment contains a polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less. By containing such a polybutylene terephthalate resin having a low intrinsic viscosity, a resin composition having excellent electromagnetic wave shielding properties can be obtained.

[0041] The polybutylene terephthalate resin used in the resin composition of the present embodiment is a polyester resin having a structure in which a terephthalic acid unit and a 1,4-butanediol unit are ester-bonded, and includes, in addition to the polybutylene terephthalate resin (homopolymer), a polybutylene terephthalate copolymer containing other copolymer components other than the terephthalic acid unit and the 1,4-butanediol unit, and a mixture of a homopolymer and a polybutylene terephthalate copolymer.

[0042] The polybutylene terephthalate resin may contain one or two or more dicarboxylic acid units other than terephthalic acid.

[0043] Specific examples of other dicarboxylic acids include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 1,5-naphthalene dicarboxylic acid, 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, bis(4,4'-carboxyphenyl)methane, anthracene dicarboxylic acid, and 4,4'-diphenyl ether dicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexane dicarboxylic acid and 4,4'-dicyclohexyl dicarboxylic acid; and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and dimer acid.

[0044] In the polybutylene terephthalate resin used in the present embodiment, the terephthalic acid unit preferably accounts for 80 mol % or more, and more preferably accounts for 90 mol % or more, of all dicarboxylic acid units.

[0045] As the diol unit, in addition to 1,4-butanediol, one or more other diol units may be contained.

[0046] Specific examples of other diol units include aliphatic or alicyclic diols having 2 to 20 carbon atoms, bisphenol derivatives, etc. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decanediol, cyclohexanedimethanol, 4,4'-dicyclohexylhydroxymethane, 4,4'-dicyclohexylhydroxypropane, and ethylene oxide addition diols of bisphenol A. In addition to the above-mentioned bifunctional monomers, a small amount of trifunctional monomers such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane for introducing a branched structure, and monofunctional compounds such as fatty acids for adjusting the molecular weight can also be used in combination.

[0047] In the polybutylene terephthalate resin used in the present embodiment, 1,4-butanediol units preferably account for 80 mol% or more, and more preferably account for 90 mol% or more of all diol units.

[0048] As described above, the polybutylene terephthalate resin is preferably a polybutylene terephthalate homopolymer formed by polycondensing terephthalic acid and 1,4-butanediol. In addition, it can also be a polybutylene terephthalate copolymer containing one or more dicarboxylic acids other than the above-mentioned terephthalic acid as carboxylic acid units and / or containing one or more diols other than the above-mentioned 1,4-butanediol as diol units. In the case where the polybutylene terephthalate resin is a polybutylene terephthalate resin modified by copolymerization, as its specific preferred copolymer, polyester ether resins formed by copolymerizing polyalkylene glycols, especially polytetramethylene glycol, dimer acid copolymerized polybutylene terephthalate resins, and isophthalic acid copolymerized polybutylene terephthalate resins can be cited. Among them, it is preferred to use a polyester ether resin formed by copolymerizing polytetramethylene glycol.

[0049] It should be noted that these copolymers refer to copolymers whose copolymerization amount is 1 mol% or more and less than 50 mol% in all segments of polybutylene terephthalate resin. Among them, the copolymerization amount is preferably 2 mol% or more and less than 50 mol%, more preferably 3 to 40 mol%, and further preferably 5 to 20 mol%. By setting such a copolymerization ratio, there is a tendency that fluidity, toughness, and tracking resistance are easily improved, so it is preferred.

[0050] The terminal carboxyl amount of polybutylene terephthalate resin can be determined by appropriate selection, usually below 60eq / ton, preferably below 50eq / ton, and more preferably below 30eq / ton. By being set below the above upper limit, there is a tendency that alkali resistance and hydrolysis resistance improve. The lower limit of the terminal carboxyl amount is not particularly limited, and considering the manufacturing productivity of polybutylene terephthalate resin, it is usually more than 10eq / ton.

[0051] It should be noted that the terminal carboxyl group amount of the polybutylene terephthalate resin is a value measured by dissolving 0.5 g of the polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. As a method for adjusting the terminal carboxyl group amount, any method known in the art may be used, such as a method for adjusting polymerization conditions such as a raw material input ratio, a polymerization temperature, and a decompression method during polymerization, or a method for reacting an end-capping agent.

[0052] The intrinsic viscosity of the polybutylene terephthalate resin is 0.80 dL / g or less, preferably 0.75 dL / g or less, and more preferably 0.72 dL / g or less. By setting it below the above upper limit, the breakage of the carbon fiber in the molten state can be effectively suppressed, and there is a tendency to improve electromagnetic wave shielding. In addition, as a lower limit, for example, it is preferably 0.4 dL / g or more, more preferably 0.5 dL / g or more, and further preferably 0.6 dL / g or more. By setting it above the above lower limit, there is a tendency to improve mechanical properties.

[0053] The intrinsic viscosity of the polybutylene terephthalate resin is a value measured at 30° C. in a mixed solvent of tetrachloroethane and phenol at a ratio of 1:1 (mass ratio).

[0054] The polybutylene terephthalate resin can be produced by melt-polymerizing a dicarboxylic acid component mainly composed of terephthalic acid or its ester derivatives with a diol component mainly composed of 1,4-butanediol in a batch or continuous manner. In addition, after the polybutylene terephthalate resin with a low molecular weight is produced by melt polymerization, it is further solid-phase polymerized under a nitrogen gas stream or under reduced pressure to increase the degree of polymerization (or molecular weight) to a desired value.

[0055] The polybutylene terephthalate resin is preferably obtained by a production method of continuously melt-polycondensing a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of 1,4-butanediol.

[0056] The catalyst used in the esterification reaction may be a conventionally known catalyst, for example, titanium compounds, tin compounds, magnesium compounds, calcium compounds, etc. Among them, titanium compounds are particularly preferred. Specific examples of titanium compounds as esterification catalysts include titanium alkoxides such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.

[0057] The content of the polybutylene terephthalate resin in the resin composition of the present embodiment is preferably 30% by mass or more, more preferably 35% by mass or more, further preferably 37% by mass or more, and further preferably 40% by mass or more in the resin composition. In addition, the content of the polybutylene terephthalate resin is preferably 65% ​​by mass or less, more preferably 62% by mass or less, further preferably 60% by mass or less, further preferably 58% by mass or less, and further preferably 52% by mass or less.

[0058] <Thermoplastic resin (X) having a lower SP value than polybutylene terephthalate resin>

[0059] The resin composition of the present embodiment includes a thermoplastic resin (X) having an SP value lower than that of the above-mentioned polybutylene terephthalate resin. It is speculated that by preparing an alloy with a resin composition having an SP value lower than that of the polybutylene terephthalate resin, in the resin composition or the molded product, the carbon fiber is relatively concentrated in the polybutylene terephthalate resin region compared with the thermoplastic resin (X) region, and the carbon fiber is more effectively dispersed in the resin composition or the molded product, which can make the effect of the present invention more effectively dispersed, and as a result, the electromagnetic wave shielding property can be further improved. In addition, the fluidity of the resin composition can be further improved.

[0060] Furthermore, the thermoplastic resin (X) used in the present embodiment includes a recycled product (recycled thermoplastic resin (X)). In the resin composition of the present embodiment, even though a recycled product is used as the thermoplastic resin (X) (e.g., polystyrene resin (PS)), performance comparable to that when a virgin thermoplastic resin (X) (e.g., polystyrene resin (PS)) is used can be achieved.

[0061] In this embodiment, the SP value is a solubility parameter, and the solubility in a solvent having a known SP value can be obtained. Based on this, calculation is performed using Hansen Solubility Parameter in Practice ver. 5.0.

[0062] The thermoplastic resin (X) can be used without particular limitation as long as it has an SP value lower than that of the polybutylene terephthalate resin.

[0063] In the present embodiment, the ratio of the SP value of the polybutylene terephthalate resin to the SP value (X) of the thermoplastic resin (X), ie, X / PBT, is greater than 0.1 and less than 1.0. By setting it within the above range, there is a tendency for the electromagnetic shielding property to be improved.

[0064] The X / PBT is preferably 0.2 or more, more preferably 0.3 or more, further preferably 0.4 or more, and may be 0.5 or more, and further may be 0.7 or more. In addition, the X / PBT is preferably 0.9 or less, and more preferably 0.8 or less.

[0065] The thermoplastic resin (X) used in the present embodiment may preferably be polyester resin (thermoplastic polyester resin); polyamide resin; polycarbonate resin; polystyrene resin; polyolefin resins such as polyethylene resin, polypropylene resin, and cyclic cycloolefin resin; polyacetal resin; polyimide resin; polyetherimide resin; polyurethane resin; polyphenylene ether resin; polyphenylene sulfide resin; polysulfone resin; polymethacrylate resin, etc., and more preferably selected from polyester resin, polystyrene resin, and polyolefin resin.

[0066] An example of the thermoplastic resin (X) used in the present embodiment is selected from polyester resins and polystyrene resins.

[0067] Another example of the thermoplastic resin (X) used in the present embodiment is selected from polyolefin resins and polystyrene resins, and is preferably selected from polyolefin elastomers and styrene elastomers.

[0068] In the present embodiment, the thermoplastic resin (X) more preferably includes a polystyrene-based resin, and further preferably includes HIPS (preferably polystyrene containing butadiene rubber).

[0069] Examples of the polystyrene resin include homopolymers of styrene monomers, copolymers of styrene monomers and monomers copolymerizable with styrene monomers, etc. Examples of styrene monomers include styrene, α-methylstyrene, chlorostyrene, methylstyrene, and tert-butylstyrene. In the present embodiment, 50 mol% or more of the monomer units of the polystyrene resin are styrene monomers.

[0070] A preferred example of the polystyrene-based resin used in the present embodiment is a styrene-based elastomer.

[0071] More specifically, polystyrene resins include polystyrene resins, acrylonitrile-styrene copolymers (AS resins), high impact polystyrene resins (HIPS), acrylonitrile-butadiene-styrene copolymers (ABS resins), acrylonitrile-acrylic rubber-styrene copolymers (AAS resins), acrylonitrile-styrene-acrylic rubber copolymers (ASA resins), acrylonitrile-ethylene propylene rubber-styrene copolymers (AES resins), styrene-IPN type rubber copolymers and the like.

[0072] In the present embodiment, the polystyrene resin is preferably acrylonitrile-styrene copolymer (AS resin), general-purpose polystyrene (GPPS), high-impact polystyrene resin (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), and styrene-IPN type rubber copolymer, more preferably general-purpose polystyrene (GPPS) and high-impact polystyrene resin (HIPS), and further preferably general-purpose polystyrene (GPPS).

[0073] When the polystyrene resin contains a rubber component, the content of the rubber component in the polystyrene resin is preferably 3 to 70% by mass, more preferably 5 to 50% by mass, and further preferably 7 to 30% by mass. By setting the content of the rubber component to 3% by mass or more, there is a tendency to improve impact resistance, and by setting it to 50% by mass or less, there is a tendency to improve flame retardancy, so it is preferred. In addition, the average particle size of the rubber component is preferably 0.05 to 10 μm, more preferably 0.1 to 6 μm, and further preferably 0.2 to 3 μm. If the average particle size is 0.05 μm or more, there is a tendency to easily improve impact resistance, and if it is 10 μm or less, there is a tendency to improve appearance, so it is preferred.

[0074] The weight average molecular weight of the polystyrene resin is usually 50,000 or more, preferably 100,000 or more, more preferably 150,000 or more, and is usually 500,000 or less, preferably 400,000 or less, and more preferably 300,000 or less. In addition, the number average molecular weight is usually 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and is preferably 500,000 or less, and more preferably 300,000 or less.

[0075] The melt flow rate (MFR) of the polystyrene resin measured in accordance with JIS K7210 (temperature 200°C, load 5 kgf) is preferably 0.1 to 30 g / 10 minutes, more preferably 0.5 to 25 g / 10 minutes. If the MFR is 0.1 g / 10 minutes or more, the fluidity tends to be improved, and if it is 30 g / 10 minutes or less, the impact resistance tends to be improved.

[0076] Examples of the method for producing such a polystyrene-based resin include known methods such as emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization.

[0077] The polyolefin resin is preferably a resin in which olefins such as ethylene, propylene, and 1-butene account for 50% by mass or more (preferably 60% by mass or more, more preferably 70% by mass, and further preferably 90% by mass). More specifically, polyethylene, polypropylene, and ethylene-propylene copolymers can be exemplified. In addition, a polyolefin-based elastomer can also be used.

[0078] Examples of the recycled thermoplastic resin (for example, recycled polystyrene resin and / or recycled polystyrene resin, preferably recycled polystyrene resin) include resins obtained by recycling materials obtained by crushing, washing and reusing recycled used thermoplastic resin (for example, used polystyrene resin) molded products, resins obtained by chemical regeneration (chemical decomposition method) and resins obtained by mechanical regeneration.

[0079] Chemical regeneration is a method of chemically decomposing the recycled used thermoplastic resin (e.g., used polystyrene resin) molded products to restore them to the raw material level and then synthesizing thermoplastic resin (e.g., recycled polystyrene resin). On the other hand, mechanical regeneration is a method of removing dirt from thermoplastic resin (e.g., polystyrene resin) molded products more reliably than material regeneration by more strictly performing the alkali cleaning in the above-mentioned material regeneration or vacuum drying at high temperature.

[0080] For example, after removing foreign matter from a used thermoplastic resin (eg, used polystyrene resin) molded article, the article is pulverized and washed, and then pelletized using an extruder to obtain a recycled thermoplastic resin (eg, recycled polystyrene resin).

[0081] In the resin composition of the present embodiment, as the thermoplastic resin (X) (preferably a polystyrene resin), only a recycled product may be included, or both a recycled product and a virgin product may be included. In the present embodiment, with respect to 100 parts by mass of the thermoplastic resin (X) (preferably a polystyrene resin) contained in the resin composition, preferably 50 to 100 parts by mass are recycled products, more preferably 80 to 100 parts by mass are recycled products, and further preferably 90 to 100 parts by mass are recycled products.

[0082] The total content of the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably polystyrene resin) in the resin composition of the present embodiment is preferably 50 mass % or more in the resin composition, more preferably 55 mass % or more, further preferably 60 mass % or more, further preferably 65 mass % or more, and further preferably 70 mass % or more. By being set to more than the above-mentioned lower limit, there is a tendency that the fluidity of the resin composition is further improved. In addition, the total content of the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably polystyrene resin) in the resin composition of the present embodiment is preferably 90 mass % or less in the resin composition, more preferably 85 mass % or less, further preferably 83 mass % or less, and further preferably 80 mass % or less. By being set to less than the above-mentioned upper limit, there is a tendency that mechanical strength is further improved.

[0083] The resin composition of the present embodiment may contain only one kind of each of the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably a polystyrene-based resin), or may contain two or more kinds.

[0084] <Carbon Fiber>

[0085] The resin composition of the present embodiment contains carbon fibers. By containing carbon fibers, the electromagnetic wave shielding properties of the obtained molded article can be improved.

[0086] The type of carbon fiber is not particularly limited, but it is preferable to use either polyacrylonitrile carbon fiber (PAN fiber) or pitch carbon fiber using pitch, and polyacrylonitrile carbon fiber (PAN fiber) is more preferable.

[0087] Furthermore, carbon fibers having a tensile strength of 5.0 GPa or less (preferably 3.5 to 5.0 GPa) as measured at 23° C. in accordance with JIS R7601 may be used.

[0088] The carbon fibers are preferably chopped strands.

[0089] The lower limit of the number average fiber length (cut length) of carbon fibers is preferably 2 mm or more, more preferably 3 mm or more, and the upper limit of the number average fiber length is preferably 10 mm or less, more preferably 8 mm or less, and further preferably 7 mm or less.

[0090] The number average fiber diameter of the carbon fibers is preferably 3 to 20 μm, more preferably 5 to 15 μm. By using carbon fibers in such a range, the obtained molded product can have an excellent balance between mechanical strength and appearance.

[0091] Specific examples of carbon fibers include TORAYCA manufactured by Toray Industries, Inc., Besfight Filament manufactured by Toho Tenax Co., Ltd., and Pyrofil manufactured by Mitsubishi Chemical Corporation.

[0092] The content of the carbon fiber in the resin composition of the present embodiment is 5% by mass or more in the resin composition, preferably 10% by mass or more, more preferably 11% by mass or more, further preferably 12% by mass or more, further preferably 12.5% ​​by mass or more, further preferably 13% by mass or more, and further preferably 14% by mass or more. By setting it to more than the above-mentioned lower limit, there is a tendency for electromagnetic wave shielding to be further improved. In addition, the upper limit of the content of the above-mentioned carbon fiber is less than 30% by mass in the resin composition, preferably less than 28% by mass, more preferably less than 26% by mass, further preferably less than 24% by mass, further preferably less than 22% by mass, and further preferably less than 21% by mass. By setting it to less than the above-mentioned upper limit, there is a tendency for fluidity to be improved during molding.

[0093] The resin composition of the present embodiment may contain only one type of carbon fiber, or may contain two or more types. When containing two or more types, the total amount is preferably within the above range.

[0094] <Compatibilizer>

[0095] The resin composition of the present embodiment preferably further contains a compatibilizer. By containing a compatibilizer, compatibilization between the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably a polystyrene resin) can be promoted, and excellent mechanical strength and excellent appearance can be easily obtained.

[0096] The compatibilizer is not particularly limited as long as it can exert a compatibilizing function between the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably a polystyrene-based resin). In the present embodiment, a polymer compound-based compatibilizer is preferred from the viewpoint of heat resistance.

[0097] As the compatibilizer, polycarbonate resin and / or styrene-maleic acid copolymer are preferred, and polycarbonate resin is more preferred. The polycarbonate resin may be a recycled product (recycled polycarbonate resin).

[0098] The polycarbonate resin is a branchable thermoplastic polymer or copolymer obtained by reacting a dihydroxy compound or a dihydroxy compound and a small amount of a polyhydroxy compound with phosgene or a carbonic acid diester.

[0099] The raw material dihydroxy compound does not substantially contain bromine atoms, and is preferably an aromatic dihydroxy compound. Specifically, 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, 4,4-dihydroxybiphenyl, etc. can be mentioned, and bisphenol A can be preferably mentioned. In addition, a compound in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compounds can also be used.

[0100] As the polycarbonate resin, among the above, preferably an aromatic polycarbonate resin derived from 2,2-bis(4-hydroxyphenyl)propane, or an aromatic polycarbonate copolymer derived from 2,2-bis(4-hydroxyphenyl)propane and other aromatic dihydroxy compounds. In addition, it can also be a copolymer with an aromatic polycarbonate resin as the main body, such as a copolymer with a polymer or oligomer having a siloxane structure. Furthermore, two or more of the above polycarbonate resins can also be used in combination.

[0101] In order to adjust the molecular weight of the polycarbonate resin, a monovalent aromatic hydroxy compound may be used, and examples thereof include m-cresol and p-cresol, m-propylphenol and p-propylphenol, p-tert-butylphenol, and p-long-chain alkyl-substituted phenol.

[0102] The viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 10,000 or more, more preferably 12,000 or more, further preferably 13,000 or more, and particularly preferably greater than 14,000. If a polycarbonate resin having a viscosity average molecular weight lower than 10,000 is used, the resulting resin composition is likely to have low mechanical strengths such as impact resistance. In addition, Mv is preferably 60,000 or less, more preferably 40,000 or less, further preferably 35,000 or less, further preferably 30,000 or less, and may also be 25,000 or less, 20,000 or less. When higher than 60,000, the fluidity of the resin composition sometimes deteriorates and the moldability deteriorates.

[0103] In the present invention, the viscosity average molecular weight (Mv) of the polycarbonate resin refers to a value calculated from the following Schnell viscosity formula by measuring the viscosity of a dichloromethane solution of the polycarbonate resin at 25°C using an Ubbelohde viscometer to determine the intrinsic viscosity ([η]).

[0104] [η] = 1.23 × 10 -4 Mv 0.83

[0105] The melt flow rate (MFR) of the polycarbonate resin measured in accordance with JIS K7210 (temperature 300° C., load 1.20 kgf) is preferably 3 g / 10 minutes or more, more preferably 6 g / 10 minutes or more, and further preferably 10 g / 10 minutes or more, and is preferably 100 g / 10 minutes or less, and more preferably 70 g / 10 minutes or less. When the MFR is within the above range, the effect of the present invention tends to be more effectively exerted.

[0106] The melt volume rate (MVR) of the polycarbonate resin measured in accordance with JIS K7210 (temperature 300° C., load 1.20 kgf) is preferably 0.5 to 20 cm 3 g / 10 minutes, more preferably 1 to 10 cm 3 When the MVR is within the above range, the effects of the present invention tend to be more effectively exhibited.

[0107] The method for producing the polycarbonate resin is not particularly limited, and a polycarbonate resin produced by any of the phosgene method (interfacial polymerization method) and the melt method (ester exchange method) can be used. In addition, a polycarbonate resin produced by the melt method is preferably obtained by post-treatment to adjust the amount of terminal OH groups.

[0108] Examples of the recycled polycarbonate resin include resins obtained by recycling materials obtained by crushing, washing and reusing recovered used polycarbonate resin molded products, resins obtained by chemical recycling (chemical decomposition method), and resins obtained by mechanical recycling.

[0109] Chemical regeneration is a method of chemically decomposing the recycled used polycarbonate resin molded products to restore them to the raw material level and then synthesizing polycarbonate resin. On the other hand, mechanical regeneration is a method of removing dirt from polycarbonate resin molded products more reliably than material regeneration by more strictly performing the alkali cleaning in the above-mentioned material regeneration or vacuum drying at high temperature.

[0110] For example, foreign matter is removed from a used polycarbonate resin molded product, the product is crushed and washed, and then pelletized using an extruder to obtain a recycled polycarbonate resin.

[0111] In the resin composition of the present embodiment, as the polycarbonate resin, only a recycled product may be included, or both a recycled product and a virgin product may be included. In the present embodiment, relative to 100 parts by mass of the polycarbonate resin contained in the resin composition, preferably 50 to 100 parts by mass are recycled products, more preferably 80 to 100 parts by mass are recycled products, and further preferably 90 to 100 parts by mass are recycled products.

[0112] As the styrene-maleic acid copolymer, the description in paragraphs 0048 to 0050 of JP-A-2020-176159 can be referred to, the contents of which are incorporated into the present specification.

[0113] In the case where the resin composition of the present embodiment includes a compatibilizer, its content is preferably more than 1 mass part relative to a total of 100 mass parts of polybutylene terephthalate resin and thermoplastic resin (X) (preferably polystyrene resin), more preferably more than 3 mass parts, more preferably more than 4 mass parts, more preferably more than 5 mass parts, and more preferably more than 6 mass parts. By being set to more than the above-mentioned lower limit, the compatibility of polybutylene terephthalate resin and thermoplastic resin (X) (preferably polystyrene resin) is improved, and there is a tendency of mechanical properties and excellent appearance. In addition, relative to a total of 100 mass parts of polybutylene terephthalate resin and thermoplastic resin (X) (preferably polystyrene resin), the upper limit of the content of the above-mentioned compatibilizer is preferably less than 30 mass parts, more preferably less than 25 mass parts, more preferably less than 18 mass parts, more preferably less than 15 mass parts, and more preferably less than 12 mass parts. By being set to less than the above-mentioned upper limit, electromagnetic wave shielding and fluidity can be further improved.

[0114] The resin composition of the present embodiment may contain only one type of compatibilizer or may contain two or more types. When containing two or more types, the total amount is preferably within the above range.

[0115] <Other ingredients>

[0116] The resin combination of the present embodiment can contain other components other than the above as required as long as it does not significantly damage the desired physical properties. If the example of other components is given, reinforcing materials (glass fibers, etc.) other than carbon fiber, various resin additives, etc. can be given. It should be noted that other components can contain 1 kind, or can contain more than 2 kinds in any combination and ratio.

[0117] Examples of various resin additives include stabilizers, mold release agents, flame retardants, reactive compounds, pigments, dyes, ultraviolet absorbers, antistatic agents, antifogging agents, antiblocking agents, fluidity improvers, plasticizers, dispersants, antibacterial agents, etc. The resin composition of this embodiment preferably contains at least one of a stabilizer and a mold release agent.

[0118] The resin composition of the present embodiment can be adjusted to: the total of polybutylene terephthalate resin, thermoplastic resin (X) (preferably polystyrene resin), carbon fiber and other selectively matched components is 100% by mass. An example of the resin composition of the present embodiment is that the total of polybutylene terephthalate resin, thermoplastic resin (X) (preferably polystyrene resin) and carbon fiber accounts for more than 95% by mass of the resin composition. In addition, another example of the resin composition of the present embodiment is that the total of polybutylene terephthalate resin, thermoplastic resin (X) (preferably polystyrene resin), carbon fiber and stabilizer accounts for more than 99% by mass of the resin composition.

[0119] <<Stabilizer>>

[0120] The resin composition of the present embodiment may contain a stabilizer. Examples of the stabilizer include hindered phenol compounds, hindered amine compounds, phosphorus compounds, sulfur stabilizers, etc. Among them, hindered phenol compounds are preferred. In addition, it is also preferred to use hindered phenol compounds and phosphorus compounds in combination.

[0121] As the stabilizer, specifically, reference may be made to paragraphs 0046 to 0057 of JP-A-2018-070722, paragraphs 0030 to 0037 of JP-A-2019-056035, and paragraphs 0066 to 0078 of International Publication No. 2017 / 038949, and these contents are incorporated into this specification.

[0122] In the resin composition of the present embodiment, preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.08 parts by mass or more of a stabilizer is contained relative to 100 parts by mass of the total of the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably a polystyrene resin). In addition, the upper limit of the content of the stabilizer is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less relative to 100 parts by mass of the total of the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably a polystyrene resin).

[0123] The resin composition of the present embodiment may contain only one stabilizer or two or more thereof. When containing two or more stabilizers, the total amount is preferably within the above range.

[0124] <<Release agent>>

[0125] The resin composition of the present embodiment preferably contains a release agent.

[0126] As the mold release agent, a wide range of known mold release agents can be used, and esters of aliphatic carboxylic acids, paraffin wax, polystyrene wax, and polyolefin wax are preferred, and polyethylene wax is more preferred.

[0127] As the release agent, specifically, reference may be made to paragraphs 0115 to 0120 of Japanese Patent Application Publication No. 2013-007058, paragraphs 0063 to 0077 of Japanese Patent Application Publication No. 2018-070722, and paragraphs 0090 to 0098 of Japanese Patent Application Publication No. 2019-123809, and these contents are incorporated into this specification.

[0128] In the resin composition of the present embodiment, preferably 0.01 parts by mass or more, more preferably 0.08 parts by mass or more, and even more preferably 0.2 parts by mass or more of a release agent is contained relative to 100 parts by mass of the total of the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably a polystyrene resin). In addition, the upper limit of the content of the release agent is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and even more preferably 0.8 parts by mass or less relative to 100 parts by mass of the total of the polybutylene terephthalate resin and the thermoplastic resin (X) (preferably a polystyrene resin).

[0129] The resin composition may contain only one type of release agent or two or more types. When containing two or more types, the total amount is preferably within the above range.

[0130] <Physical Properties>

[0131] The resin composition of the present embodiment has excellent electromagnetic wave shielding properties. Specifically, the electromagnetic wave shielding properties of the resin composition of the present embodiment at a frequency of 100MHz are preferably below -40.0, more preferably below -41.0, and further preferably below -42.0. The lower limit of the above-mentioned electromagnetic wave shielding properties is not particularly limited, but is actually above -55.0.

[0132] In addition, the electromagnetic wave shielding property of the resin composition of the present embodiment at a frequency of 200MHz is preferably below -30.0, more preferably below -34.0, further preferably below -36.0, and may be below -36.5, below -37.0, or below -37.5 depending on the application, etc. The lower limit of the electromagnetic wave shielding property is not particularly limited, but is actually above -51.0.

[0133] The resin composition of the present embodiment has excellent impact resistance. Specifically, when molded into an ISO tensile test piece (4 mm thick), the notched Charpy impact strength according to ISO179 is preferably 3 kJ / m 2 More preferably 4 kJ / m 2 The higher the upper limit, the better, but the actual upper limit is 10kJ / m 2 the following.

[0134] The resin composition of the present embodiment has excellent heat resistance. Specifically, when molded into an ISO multi-purpose test piece (4 mm thick), the load deflection temperature measured under a load of 1.80 MPa according to ISO75-1 and ISO75-2 is preferably 190°C or more, more preferably 191°C or more, further preferably 192°C or more, and further preferably 195°C or more. The higher the upper limit, the better, but it is actually below 230°C.

[0135] The above electromagnetic wave shielding properties and Charpy impact strength (kJ / m 2 ) and deflection temperature under load (DTUL) (° C.) were measured according to the description in the examples described below.

[0136] <Method for producing resin composition>

[0137] The resin composition of the present embodiment can be manufactured by the conventional method of the resin composition comprising a thermoplastic resin. It can be manufactured by putting polybutylene terephthalate resin, thermoplastic resin (X) (preferably polystyrene resin), carbon fiber, and other components matched as needed into an extruder, and performing melt mixing. A form formed by such a resin composition is a pellet.

[0138] In the extruder, the components may be mixed in advance and supplied at once, or the components may not be mixed in advance, or only a part of them may be mixed in advance and supplied to the extruder using a feeder. The extruder may be a single-screw extruder or a twin-screw extruder.

[0139] In addition, the carbon fibers are preferably supplied from a side feeder in the middle of the cylinder of the extruder.

[0140] The heating temperature during melt kneading can be appropriately selected usually from the range of 150 to 350°C.

[0141] <Production method of molded products>

[0142] The molded article of the present embodiment is formed from the resin composition or pellets of the present embodiment.

[0143] The manufacturing method of the molded product in the present embodiment is not particularly limited, and any molding method commonly used for the resin composition containing thermoplastic resin can be arbitrarily adopted. If its example is given, then injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted hollow molding, molding using an insulating mold, molding using a rapid heating mold, foam molding (also including supercritical fluid), insert molding, IMC (in-mold coating molding), extrusion molding, sheet molding, thermoforming, rotational molding, stacking molding, compression molding, blow molding, etc. can be given, wherein injection molding is preferred.

[0144] <Application Areas>

[0145] The application field of the molded product formed by the resin combination or pellets of the present embodiment is not particularly limited, and is preferably used as the purposes (for electromagnetic wave shielding) requiring electromagnetic wave shielding. As the purposes requiring electromagnetic wave shielding, for example, the housing purposes, connectors, packaging materials etc. of the mobile communication devices such as OA equipment, AV equipment, connector parts, air purifiers, IoT home appliances (home appliances capable of carrying out Internet communication), smart phones, radio wave base stations, measuring equipment, transportation equipment, communication equipment, radar devices etc. can be enumerated. As the purposes especially for automobiles, electronic control unit housing, power control unit housing, camera housing, battery cover for electric vehicles etc. can be enumerated. In addition, the automobile purposes requiring high rigidity can also be enumerated.

[0146] Example

[0147] The present invention is described in more detail below with reference to the following examples. The materials, usage, ratio, processing contents, processing steps, etc. shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0148] When the measuring equipment used in the examples is difficult to obtain due to discontinuation of production or the like, other equipment having equivalent performance may be used for the measurement.

[0149] 1. Raw materials

[0150] The following ingredients were used.

[0151] [Table 1]

[0152]

[0153] Examples 1 to 12, Comparative Examples 1 to 7

[0154] <Production of resin composition (pellets)>

[0155] The components listed in Table 1 were placed in a stainless steel drum in the amounts shown in Tables 2 to 5 (the unit of the amount is parts by mass), and stirred and mixed for 1 hour. The resulting mixture was supplied from the main feed port to an intermeshing co-rotating twin-screw extruder ("TEX-30α" manufactured by Nippon Steel Works, Ltd., screw diameter 32 mm, L / D = 42). The barrel temperature of the first kneading section was set to 270°C, and melt kneading was carried out under the conditions of a discharge rate of 30 kg / h and a screw speed of 200 rpm. The nozzle number was 5 holes (round The extruded strands were introduced into a water tank for cooling, and then inserted into a pelletizer for cutting to obtain a resin composition (pellets).

[0156] <Electromagnetic wave shielding properties>

[0157] The resin pellets obtained above were dried at 120°C for 5 hours and then injection molded into a 150×150×2 mm flat plate test piece using an injection molding machine (EC160 manufactured by Shibaura Machine Co., Ltd.) at a cylinder temperature of 260°C and a mold temperature of 80°C.

[0158] The electromagnetic wave shielding property (electric field) of the molded flat plate test piece was measured by the KEC method. A network analyzer "N5230A" manufactured by Agilent Technologies was used for the measurement.

[0159] The unit of electromagnetic shielding property is (dB). The lower the value of electromagnetic shielding property, the better it is.

[0160] <Tensile strength, tensile elastic modulus, and tensile strain>

[0161] The resin pellets obtained above were dried at 120°C for 5 hours and then injection molded into ISO multi-purpose test pieces (thickness 4 mm) using an injection molding machine ("J85AD" manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 250°C and a mold temperature of 80°C.

[0162] Using the molded multipurpose ISO multipurpose test piece, the tensile strength (unit: MPa), tensile elastic modulus (unit: MPa) and tensile strain (unit: %) were measured in accordance with ISO527-1 and ISO527-2.

[0163] <Flexural strength and flexural modulus>

[0164] An injection molding machine (Sumitomo Heavy Industries, Ltd., Model SE50) was used at an injection molding speed of 30 mm / sec, a screw diameter of 28 mm (injection rate: 18.5 cm 3 / sec), resin temperature of 260°C, and mold temperature of 80°C, an ISO tensile test piece having a thickness of 4 mm was produced from the obtained resin composition (pellets).

[0165] The flexural strength (unit: MPa) and the flexural modulus (unit: MPa) were measured at a temperature of 23° C. using the above-mentioned ISO tensile test piece (4 mm thick) in accordance with ISO 178.

[0166] <Charpy impact strength (with notch)

[0167] An injection molding machine (Sumitomo Heavy Industries, Ltd., Model SE50) was used at an injection molding speed of 30 mm / sec, a screw diameter of 28 mm (injection rate: 18.5 cm 3 / sec), resin temperature 260°C, and mold temperature 80°C, an ISO tensile test piece having a thickness of 4 mm was produced from the obtained resin composition (pellets).

[0168] The Charpy impact strength (with notch) was measured using the above-mentioned ISO tensile test piece (4 mm thick) in accordance with ISO 179. Note that NB means non-breakage.

[0169] The unit is kJ / m 2 express.

[0170] <Deflection Temperature Under Load (DTUL)>

[0171] Using the above-mentioned ISO multipurpose test piece (4 mm thick), the load deflection temperature (unit: ° C.) was measured under a load of 1.80 MPa in accordance with ISO75-1 and ISO75-2.

[0172] <Peak pressure during injection molding (fluidity)>

[0173] After the resin pellets obtained above were dried at 120°C for 5 hours, they were injection molded into 150×150×2 mm flat test pieces using an injection molding machine ("EC160" manufactured by Shibaura Machine Co., Ltd.) at a barrel temperature of 260°C, a mold temperature of 80°C, and a filling time of 1.0 second. The injection peak pressure at this time is expressed in units (MPa).

[0174] It can be said that the lower the peak pressure, the better the fluidity.

[0175] [Table 2]

[0176]

[0177] [Table 3]

[0178]

[0179] [Table 4]

[0180]

[0181] [Table 5]

[0182]

[0183] In the above table, X / PBT represents the mass ratio of the polybutylene terephthalate resin (PBT) to the above thermoplastic resin (X).

[0184] The above results show that the resin composition of the present invention is excellent in electromagnetic wave shielding properties and fluidity, and is also excellent in mechanical strength and heat resistance (Examples 1 to 12).

[0185] In particular, even though recycled resin was used as the polystyrene resin, performance equivalent to that when virgin polystyrene resin was used was achieved (Examples 10 and 11).

[0186] In contrast, when no polystyrene resin is included (Comparative Examples 1 and 2), the fluidity is poor. In addition, when the viscosity of the polybutylene terephthalate resin is high (Comparative Examples 3 and 4), the electromagnetic wave shielding property is poor. On the other hand, when the proportion of the polystyrene resin is too high relative to the polybutylene terephthalate resin (Comparative Examples 5 and 6), the electromagnetic wave shielding property is poor. Furthermore, when no compatibilizer is included (Comparative Example 7), the fluidity is poor.

Claims

1. A resin composition comprising a polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less, a thermoplastic resin having an SP value lower than that of the polybutylene terephthalate resin, and carbon fibers, wherein: SP value is the solubility parameter, The content of carbon fiber in the resin composition is 5 to 30% by mass. The mass ratio of the polybutylene terephthalate resin PBT having an intrinsic viscosity of 0.80 dL / g or less to the thermoplastic resin X, that is, X / PBT, is greater than 0.1 and less than 1.

0. 2 . The resin composition according to claim 1 , wherein the thermoplastic resin having a lower SP value than the polybutylene terephthalate resin comprises a polystyrene-based resin. 3 . The resin composition according to claim 1 , wherein the thermoplastic resin X comprises a recycled product. The resin composition according to claim 1 or 2, further comprising a compatibilizer. The resin composition according to claim 4 , wherein the compatibilizer comprises a polycarbonate resin. The resin composition according to claim 4 , wherein the compatibilizer comprises a recycled polycarbonate resin. The resin composition according to claim 1 or 2, which is used for electromagnetic wave shielding.

8. The resin composition according to claim 1, wherein the thermoplastic resin X having a lower SP value than the polybutylene terephthalate resin comprises a polystyrene resin, The resin composition further comprises a compatibilizer, The compatibilizer comprises a polycarbonate resin, The resin composition is used for electromagnetic wave shielding. 9 . The resin composition according to claim 8 , wherein the thermoplastic resin X having a lower SP value than the polybutylene terephthalate resin comprises a recycled product.

10. A resin composition comprising a polybutylene terephthalate resin having an intrinsic viscosity of 0.80 dL / g or less, a polystyrene resin and carbon fibers, The content of carbon fiber in the resin composition is 5 to 30% by mass. The mass ratio of the polybutylene terephthalate resin PBT having an intrinsic viscosity of 0.80 dL / g or less to the polystyrene-based resin, that is, PS / PBT, is greater than 0.1 and less than 1.

0. The resin composition according to claim 10 , wherein the polystyrene resin comprises a recycled product. 12 . Pellets formed from the resin composition according to claim 1 . 13 . A molded article formed from the resin composition according to claim 1 .

14. A molded article formed from the pellets according to claim 12.

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