Resin composition, pellets, molded articles, and electromagnetic wave absorbers

Abstract

The present invention provides a resin composition capable of providing molded articles with high electromagnetic wave absorption and excellent thermal conductivity, as well as pellets, molded articles, and electromagnetic wave absorbers. [Solution] The resin composition according to the present disclosure is a resin composition comprising (A) a thermoplastic resin containing a polyalkylene terephthalate resin, (B) a conductive filler, and (C) a non-conductive thermal conductive filler, wherein the average particle size of (C) the non-conductive thermal conductive filler is 10 to 100 μm, and the content of (C) the non-conductive thermal conductive filler in the resin composition is 10 to 60% by mass.

Description

[Technical Field]

[0001] This invention relates to resin compositions, pellets, molded articles, and electromagnetic wave absorbers. [Background technology]

[0002] Millimeter-wave radar emits radio waves in the millimeter-wave band with wavelengths of 1 to 10 mm and frequencies of 30 to 300 GHz, particularly 60 to 90 GHz. By receiving the reflected waves that collide with an object and return, it detects the presence of obstacles, as well as the distance and relative speed to the object. Millimeter-wave radar is being considered for use in a wide range of fields, including collision avoidance sensors in automobiles, autonomous driving systems, road information systems, security systems, and medical and nursing care devices. A resin composition for such millimeter-wave radar is known, as described in Patent Document 1. Furthermore, Patent Document 2 discloses a multi-functional resin composition that can be used for electromagnetic interference shielding or radio frequency interference shielding. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-197048 [Patent Document 2] Japanese Patent Publication No. 2010-155993 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In this case, a molded body with high electromagnetic wave absorption may also require high thermal conductivity. The present invention aims to solve the aforementioned problems and to provide a resin composition capable of providing a molded article with high electromagnetic wave absorption and excellent thermal conductivity, as well as pellets, molded articles, and electromagnetic wave absorbers. [Means for solving the problem]

[0005] Under these circumstances, the inventors conducted research and found that the above problem can be solved by incorporating a predetermined amount of a non-conductive thermal conductive filler of a predetermined size. Specifically, the above problem was solved by the following means. [1] (A) A thermoplastic resin containing polyalkylene terephthalate resin, (B) Conductive filler, (C) A resin composition comprising a non-conductive thermal conductive filler, The average particle size of the non-conductive thermal filler (C) is 10 to 100 μm. A resin composition wherein the content of (C) a non-conductive thermal conductive filler in the resin composition is 10 to 60% by mass. [2] The resin composition according to [1], wherein the content of (B) conductive filler in the resin composition is 0.1 to 40% by mass. [3] The resin composition according to [1] or [2], wherein the content of (C) non-conductive thermal conductive filler in the resin composition is 12 to 60% by mass. [4] The resin composition according to any one of [1] to [3], wherein the conductive filler (B) comprises at least one selected from the group consisting of carbon nanotubes, conductive carbon black, carbon nanostructures, and graphene. [5] The resin composition according to any one of [1] to [4], wherein the (C) nonconductive thermal conductive filler comprises at least one selected from the group consisting of talc, boron nitride, magnesium oxide, aluminum oxide, and silicon nitride. [6] The content of (B) conductive filler in the resin composition is 0.1 to 40% by mass, The content of (C) non-conductive thermal conductive filler in the resin composition is 12 to 60% by mass. The conductive filler (B) comprises at least one selected from the group consisting of carbon nanotubes, conductive carbon black, carbon nanostructures, and graphene. The resin composition according to any one of [1] to [5], wherein the (C) non-conductive thermal conductive filler comprises at least one selected from the group consisting of talc, boron nitride, magnesium oxide, aluminum oxide, and silicon nitride. [7] The resin composition according to any one of [1] to [6], further comprising glass fibers in a proportion of 10 to 50% by mass. [8] The resin composition according to any one of [1] to [7], wherein the polyalkylene terephthalate resin comprises a polybutylene terephthalate resin. [9] The resin composition according to any one of [1] to [8], wherein the (A) thermoplastic resin comprises a polycarbonate resin and / or a styrene-based resin.

[10] The resin composition according to any one of [1] to [9], wherein the absorption rate determined by formula (A) at a frequency of 76.5 GHz is 40.0 to 100% when the resin composition is molded to a thickness of 2 mm. Formula (A)

number

[11] The content of (B) conductive filler in the resin composition is 0.1 to 40% by mass, The content of (C) non-conductive thermal conductive filler in the resin composition is 12 to 60% by mass. The conductive filler (B) comprises at least one selected from the group consisting of carbon nanotubes, conductive carbon black, carbon nanostructures, and graphene. The (C) non-conductive thermal filler comprises at least one selected from the group consisting of talc, boron nitride, magnesium oxide, aluminum oxide, and silicon nitride. Furthermore, the resin composition contains glass fibers in a proportion of 10 to 50% by mass, The polyalkylene terephthalate resin includes polybutylene terephthalate resin, The above-mentioned (A) thermoplastic resin contains a polycarbonate resin and / or a styrene-based resin, The resin composition according to any one of [1] to

[10] , wherein the absorption rate determined according to formula (A) at a frequency of 76.5 GHz when the resin composition is molded to a thickness of 2 mm is 40.0 to 100%. Formula (A) [Number] (In the above formula (A), R represents the reflection attenuation amount measured by the free space method, and T represents the transmission attenuation amount measured by the free space method.)

[12] Pellets formed from the resin composition according to any one of [1] to

[11] .

[13] Molded articles formed from the resin composition according to any one of [1] to

[11] .

[14] An electromagnetic wave absorber formed from the resin composition according to any one of [1] to

[11] .

[15] An electromagnetic wave absorber formed from the pellets according to

[12] . [Effect of the Invention]

[0006] According to the present invention, a resin composition capable of providing a molded article having a high electromagnetic wave absorption rate and excellent thermal conductivity, as well as pellets, molded articles, and electromagnetic wave absorbers, has been provided. [Embodiments for Carrying Out the Invention]

[0007] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an exemplification for explaining the present invention, and the present invention is not limited only to the present embodiment. In this specification, "~" is used in the sense of including the numerical values described before and after it as lower and upper limits. Further, any combination of the upper and lower limits of the numerical values in this specification can be cited as an example of the present embodiment. In this specification, a combination of preferred embodiments is a more preferred embodiment. In this specification, all physical properties and characteristic values ​​shall be those at 23°C unless otherwise specified. In this specification, unless otherwise specified, weight-average molecular weight and number-average molecular weight are polystyrene-converted values ​​measured by GPC (gel permeation chromatography). In this specification, the units for reflection loss and transmission loss are "dB" (decibels). If the measurement methods, etc., described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2024 shall apply. If the measurement methods, etc., described in the standards shown in this specification have been discontinued as of January 1, 2024, the standards in effect at the time of discontinuation shall apply.

[0008] The resin composition of this embodiment is a resin composition comprising (A) a thermoplastic resin containing a polyalkylene terephthalate resin, (B) a conductive filler, and (C) a non-conductive thermal conductive filler, wherein the average particle size of (C) the non-conductive thermal conductive filler is 10 to 100 μm, and the content of (C) the non-conductive thermal conductive filler in the resin composition is 10 to 60% by mass. By adopting this configuration, a resin composition can be obtained that provides molded articles with high electromagnetic wave absorption and excellent thermal conductivity. (A) When a conductive filler is added to a thermoplastic resin containing polyalkylene terephthalate resin, it becomes possible to provide a molded article with excellent conductivity. Furthermore, when a thermally conductive filler is added to a thermoplastic resin containing polyalkylene terephthalate resin, it becomes possible to provide a molded article with excellent thermal conductivity. However, incorporating conductive thermal fillers into thermoplastic resins affects their electromagnetic wave absorption performance. Therefore, it is necessary to impart thermal conductivity while minimizing the impact on electromagnetic wave absorption performance. Under these circumstances, the inventors conducted research and found that by using a non-conductive material as the thermally conductive filler, and by adjusting its average particle size and content, a resin composition capable of providing a molded article with high electromagnetic wave absorption and excellent thermal conductivity can be obtained. In particular, it is presumed that by using 10% by mass or more of non-conductive thermally conductive fillers with an average particle diameter of 10 μm or more, the electromagnetic wave absorption performance exhibited by the conductive fillers will not be affected, and the thermally conductive fillers will be sufficiently dispersed and connected within the thermoplastic resin, thereby enhancing thermal conductivity.

[0009] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely one example of an embodiment of the present invention and is not limited to these.

[0010] <(A) Thermoplastic resin containing polyalkylene terephthalate resin> The resin composition of this embodiment includes a polyalkylene terephthalate resin. The polyalkylene terephthalate resin used in this embodiment is not specifically defined in terms of type, but polybutylene terephthalate resin and polyethylene terephthalate resin are examples, with polybutylene terephthalate resin being preferred. The polyalkylene terephthalate resin used in this embodiment may be recycled polyalkylene terephthalate resin (including recovered products, material recycled products, chemical recycled products, etc.), rejected products, or scraps generated when molding molded products from resin compositions.

[0011] <<Polybutylene terephthalate resin>> Polybutylene terephthalate resin is a resin obtained by polycondensation of terephthalic acid as the main component of the acid component and 1,4-butanediol as the main component of the diol component. When the main component of the acid component is terephthalic acid, it means that 50% or more by mass of the acid component is terephthalic acid, preferably 60% or more by mass, more preferably 70% or more by mass, and may be 80% or more by mass, 90% or more by mass, or 95% or more by mass. When the main component of the diol component is 1,4-butanediol, it means that 50% or more by mass of the diol component is 1,4-butanediol, preferably 60% or more by mass, more preferably 70% or more by mass, and may be 80% or more by mass, 90% or more by mass, or 95% or more by mass. When polybutylene terephthalate resin contains other acidic components, examples include isophthalic acid and dimer acid. Furthermore, when polybutylene terephthalate resin contains other diol components, examples include polyalkylene glycols such as polytetramethylene glycol (PTMG).

[0012] When using a copolymer of polytetramethylene glycol as the polybutylene terephthalate resin, the proportion of the tetramethylene glycol component in the copolymer is preferably 3 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 25% by mass. Such copolymerization ratios tend to result in a better balance between strength and heat resistance, which is preferable.

[0013] When using dimer acid copolymerized polybutylene terephthalate as the polybutylene terephthalate resin, the proportion of dimer acid components to the total carboxylic acid components is preferably 0.5 to 30 mol%, more preferably 1 to 20 mol%, and even more preferably 3 to 15 mol%. Such copolymerization ratios tend to result in an excellent balance of strength, long-term heat resistance, and toughness, which is preferable.

[0014] When using isophthalic acid copolymerized polybutylene terephthalate as the polybutylene terephthalate resin, the proportion of isophthalic acid components to the total carboxylic acid components is preferably 1 to 30 mol%, more preferably 1 to 20 mol%, and even more preferably 3 to 15 mol%. Such copolymerization ratios tend to result in an excellent balance of strength, heat resistance, injection moldability, and toughness, which is preferable.

[0015] The polybutylene terephthalate resin used in this embodiment is preferably a resin (polybutylene terephthalate homopolymer) in which 90% or more by mass of the acid component is terephthalic acid and 90% or more by mass of the diol component is 1,4-butanediol, or a copolymerized polybutylene terephthalate resin obtained by copolymerizing polytetramethylene glycol, or an isophthalic acid copolymerized polybutylene terephthalate resin.

[0016] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 dL / g or higher, more preferably 0.6 dL / g or higher, preferably 2.0 dL / g or lower, more preferably 1.5 dL / g or lower, and even more preferably 1.1 dL / g or lower. Using a polybutylene terephthalate resin with an intrinsic viscosity of 0.5 dL / g or higher tends to improve the mechanical strength of the resulting molded article. Furthermore, using a polybutylene terephthalate resin with an intrinsic viscosity of 2 dL / g or lower tends to improve the fluidity of the polybutylene terephthalate resin and thus improve moldability. The intrinsic viscosity of polybutylene terephthalate resin is measured at 30°C in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol. If the mixture contains two or more types of polybutylene terephthalate resin, the intrinsic viscosity shall be the intrinsic viscosity of the mixture.

[0017] The amount of terminal carboxyl groups in polybutylene terephthalate resin can be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 30 eq / ton or less. By limiting the amount of terminal carboxyl groups to 50 eq / ton or less, gas generation during melt molding of polybutylene terephthalate resin can be more effectively suppressed. There is no specific lower limit for the amount of terminal carboxyl groups, but it is usually 5 eq / ton. When two or more types of polybutylene terephthalate resins are included, the amount of terminal carboxyl groups shall be the amount of terminal carboxyl groups in the mixture.

[0018] The amount of terminal carboxyl groups in polybutylene terephthalate resin can be determined by dissolving 0.5 g of polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. Methods for adjusting the amount of terminal carboxyl groups include adjusting polymerization conditions such as the raw material ratio, polymerization temperature, and reduced pressure method during polymerization, as well as reacting with end-sealing agents, and any other conventionally known methods.

[0019] <<Polyethylene terephthalate resin>> The polyethylene terephthalate resin used in this embodiment is a resin obtained by polycondensing terephthalic acid as the main component of the acid component and ethylene glycol as the main component of the diol component. When the main component of the acid component is terephthalic acid, it means that 50% by mass or more of the acid component is terephthalic acid, preferably 60% by mass or more, more preferably 70% by mass or more, and may be 80% by mass or more, 90% by mass or more, or 95% by mass or more. When the main component of the diol component is ethylene glycol, it means that 50% by mass or more of the diol component is ethylene glycol, preferably 60% by mass or more, more preferably 70% by mass or more, and may be 80% by mass or more, 90% by mass or more, or 95% by mass or more.

[0020] When polyethylene terephthalate resin contains other acidic components, examples include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4'-diphenylsulfondicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid and their structural isomers, dicarboxylic acids such as malonic acid, succinic acid, and adipic acid and their derivatives, and oxyacids such as p-hydroxybenzoic acid and glycolic acid or their derivatives. Furthermore, if the polyethylene terephthalate resin contains other acidic components, other diol components may include aliphatic glycols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol, and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S.

[0021] Furthermore, the polyethylene terephthalate resin may be copolymerized with a branched component, such as a trifunctional or tetrafunctional acid like tricarbaryl acid, trimellicinic acid, or trimellitic acid, or a trifunctional or tetrafunctional alcohol like pyromellitic acid, at a concentration of 1.0 mol% or less, preferably 0.5 mol% or less, and more preferably 0.3 mol% or less.

[0022] The intrinsic viscosity of the polyethylene terephthalate resin is preferably 0.3 to 1.5 dL / g, more preferably 0.3 to 1.2 dL / g, and even more preferably 0.4 to 0.8 dL / g. The intrinsic viscosity of polyethylene terephthalate resin is measured at 30°C in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

[0023] Furthermore, the concentration of terminal carboxyl groups in the polyethylene terephthalate resin is preferably 3 to 60 eq / ton, more preferably 5 to 50 eq / ton, and even more preferably 8 to 40 eq / ton. Setting the terminal carboxyl group concentration to 60 eq / ton or less tends to reduce gas generation during melt molding of the resin material, and the mechanical properties of the resulting molded article tend to improve. Conversely, setting the terminal carboxyl group concentration to 3 eq / ton or more tends to improve the heat resistance, heat retention stability, and color of the resulting molded article, which is preferable. The concentration of terminal carboxyl groups in polyethylene terephthalate resin can be determined by dissolving 0.5 g of polyethylene terephthalate resin in 25 mL of benzyl alcohol and titrating it with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide.

[0024] The polyalkylene terephthalate resin content in the resin composition of this embodiment is preferably 20% by mass or more, and more preferably 25% by mass or more. Setting it above the lower limit tends to improve mechanical strength. Furthermore, the polyalkylene terephthalate content in the resin composition is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and even more preferably 55% by mass or less. Setting it below the upper limit tends to improve the dimensional accuracy of injection molded products. The resin composition of this embodiment may contain only one type of polyalkylene terephthalate resin, or it may contain two or more types. When two or more types are included, it is preferable that the total amount is within the above range.

[0025] The resin composition of this embodiment may also contain an amorphous thermoplastic resin as (A) thermoplastic resin. By including an amorphous resin, molded products with superior low warping and electromagnetic wave absorption rates can be obtained. Amorphous thermoplastic resins are preferably polycarbonate resins and / or styrene-based resins.

[0026] <<Polycarbonate resin>> The resin composition of this embodiment may also contain polycarbonate resin. Polycarbonate resin is a branched homopolymer or copolymer obtained by reacting a dihydroxy compound, or a small amount thereof, with a polyhydroxy compound with phosgene or a diester carbonate. The method for producing polycarbonate resin is not particularly limited, and conventionally known methods such as the phosgene method (interfacial polymerization) or the melting method (transesterification) can be used.

[0027] As the raw material dihydroxy compound, aromatic dihydroxy compounds are preferred, including 2,2-bis(4-hydroxyphenyl)propane (=bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, 4,4-dihydroxydiphenyl, and others, with bisphenol A being preferred. In addition, compounds in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compounds can also be used.

[0028] Among the polycarbonate resins mentioned above, aromatic polycarbonate resins derived from 2,2-bis(4-hydroxyphenyl)propane, or aromatic polycarbonate copolymers derived from 2,2-bis(4-hydroxyphenyl)propane and other aromatic dihydroxy compounds are preferred. Alternatively, copolymers mainly composed of aromatic polycarbonate resins, such as copolymers with polymers or oligomers having a siloxane structure, may also be used. Furthermore, two or more of the above-mentioned polycarbonate resins may be mixed and used.

[0029] To adjust the molecular weight of polycarbonate resin, monovalent aromatic hydroxy compounds can be used, such as m- and p-methylphenol, m- and p-propylphenol, p-tert-butylphenol, and p-long-chain alkyl-substituted phenols.

[0030] The viscosity-average molecular weight (Mv) of the polycarbonate resin is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 13,000 or more. Using a resin with a viscosity-average molecular weight of 5,000 or more tends to improve the mechanical strength of the resulting resin composition. Furthermore, the viscosity-average molecular weight (Mv) of the polycarbonate resin is preferably 60,000 or less, more preferably 40,000 or less, and even more preferably 30,000 or less. Using a resin with a viscosity-average molecular weight of 60,000 or less tends to improve the fluidity of the resin composition and improve its moldability. When the mixture contains two or more types of polycarbonate resin, it is preferable that the mixture satisfies the above range (the same consideration applies to molecular weight below).

[0031] In this embodiment, the viscosity-average molecular weight (Mv) of the polycarbonate resin is calculated using an Ubbelohde viscometer to determine the intrinsic viscosity ([η]) of the methylene chloride solution of the polycarbonate resin at 20°C, and the value is derived from Schnell's viscosity formula. [η] = 1.23 × 10 -4 Mv 0.83

[0032] The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resin produced by either the phosgene method (interfacial polymerization method) or the melting method (transesterification method) can be used. Furthermore, polycarbonate resin produced by the melting method and then subjected to post-treatment to adjust the amount of terminal OH groups is also preferred.

[0033] <<Styrene resin>> The resin composition of this embodiment may also contain a styrene-based resin. By using a styrene-based resin, carbon nanotubes tend to diffuse more easily into the polybutylene terephthalate resin, and the electromagnetic wave absorption of the resin composition tends to improve. Furthermore, the electromagnetic wave transmittance and reflectance of the resin composition tend to be lower. In addition, the dimensional accuracy of the injection-molded product tends to improve.

[0034] Examples of styrene-based resins include homopolymers of styrene monomers and copolymers of styrene monomers and monomers copolymerizable with styrene monomers. Examples of styrene monomers include styrene, α-methylstyrene, chlorostyrene, methylstyrene, and tert-butylstyrene. In this embodiment, the styrene-based resin contains 50 mol% or more of styrene monomers. More specifically, styrene-based resins include polystyrene resin, acrylonitrile-styrene copolymer (AS resin), high-impact polystyrene resin (HIPS, butadiene rubber-containing polystyrene), 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), styrene-IPN type rubber copolymer, and other resins. In this embodiment, the styrene-based resin is preferably an acrylonitrile-styrene copolymer (AS resin), an impact-resistant polystyrene resin (HIPS, butadiene rubber-containing polystyrene), an acrylonitrile-butadiene-styrene copolymer (ABS resin), an acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), an acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), an acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), or a styrene-IPN type rubber copolymer, and more preferably an impact-resistant polystyrene resin (HIPS, butadiene rubber-containing polystyrene). It is presumed that by alloying such a styrene-based resin with a polyalkylene terephthalate resin, carbon nanotubes selectively occupy the more polar polyalkylene terephthalate resin phase and become highly dispersed. As a result, a resin composition with highly efficient electromagnetic wave absorption tends to be obtained.

[0035] When the styrene resin contains a rubber component, the content of the rubber component in the styrene resin is preferably 3 to 70% by mass, more preferably 5 to 50% by mass, and even more preferably 7 to 30% by mass. By setting the content of the rubber component to 3% by mass or more, the impact resistance tends to improve, and by setting it to 50% by mass or less, the flame retardancy tends to improve, which is preferable. Further, the average particle diameter of the rubber component is preferably 0.05 to 10 μm, more preferably 0.1 to 6 μm, and even more preferably 0.2 to 3 μm. When the average particle diameter is 0.05 μm or more, the impact resistance tends to be easily improved, and when it is 10 μm or less, the appearance tends to improve, which is preferable.

[0036] The weight average molecular weight of the styrene resin is usually 50,000 or more, preferably 100,000 or more, more preferably 150,000 or more, and usually 500,000 or less, preferably 400,000 or less, more preferably 300,000 or less. Also, the number average molecular weight is usually 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and preferably 500,000 or less, more preferably 300,000 or less.

[0037] The melt volume rate (MVR) of the styrene resin measured in accordance with JIS K7210 (temperature 200 °C, load 5 kgf) is 0.1 cm 3 / 10 min or more is preferable, 0.5 cm 3 / 10 min or more is more preferable, 1 cm 3 / 10 min or more is even more preferable, and also 30 cm 3 / 10 min or less is preferable, 20 cm 3 / 10 min or less is more preferable, 10 cm 3 / 10 min or less is even more preferable, 7 cm 3 / 10 min or less is still more preferable, 5 cm 3It is even more preferable that the time is 10 minutes or less. Setting it above the lower limit tends to improve the fluidity of the resin composition, and setting it below the upper limit tends to improve the impact resistance.

[0038] Known methods for producing such styrene-based resins include emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization.

[0039] When the resin composition of this embodiment contains amorphous thermoplastic resin, its content is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more, based on 100 parts by mass of the total amount of thermoplastic resin (A). Setting it above the lower limit tends to improve electromagnetic wave absorption performance and dimensional accuracy of injection molded products. Furthermore, the upper limit of the amorphous thermoplastic resin content is preferably 55 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 45 parts by mass or less, based on 100 parts by mass of the total amount of thermoplastic resin (A). Setting it below the upper limit tends to further improve chemical resistance and heat resistance. The resin composition of this embodiment may contain only one type of amorphous thermoplastic resin, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0040] The total amount of (A) thermoplastic resin (the total amount of polyalkylene terephthalate resin and amorphous thermoplastic resin blended as needed) contained in the resin composition of this embodiment is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, even more preferably 43% by mass or more, and also preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 53% by mass or less.

[0041] <(B) Conductive filler> The resin composition of this embodiment includes (B) a conductive filler. By including a conductive filler, electromagnetic wave absorption properties can be imparted to the resin composition. (B) The conductive filler preferably contains at least one selected from the group consisting of carbon nanotubes, conductive carbon black, carbon nanostructures, and graphene, and more preferably contains carbon nanotubes.

[0042] The carbon nanotubes used in this embodiment are single-walled carbon nanotubes and / or multi-walled carbon nanotubes, and preferably include at least multi-walled carbon nanotubes. Carbon materials having a partially carbon nanotube structure can also be used. Furthermore, the carbon nanotubes are not limited to a cylindrical shape, but may have a coiled shape in which a helix completes one turn with a pitch of 1 μm or less. Carbon nanotubes are commercially available, and examples include those from Bayer MaterialScience, NanoSil, Showa Denko Corporation, and Hyperion Catalysis International. They are also sometimes referred to as graphite fibrils or carbon fibrils. The diameter (number-average fiber diameter) of the carbon nanotubes is preferably 0.5 to 100 nm, and more preferably 1 to 30 nm. The aspect ratio of the carbon nanotubes is preferably 5 or higher, and more preferably 50 or higher, from the viewpoint of providing good electromagnetic wave absorption. There is no specific upper limit, but for example, it is 500 or less.

[0043] In this embodiment, it is preferable that the carbon nanotubes are derived from carbon nanotubes that have been master-batched with resin. With this configuration, the electromagnetic wave absorption properties of the resulting resin composition or molded article tend to be further improved. (B) The conductive filler may be formulated in a masterbatch as described above. In this case, the concentration of (B) conductive filler in the masterbatch is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 12% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 20% by mass or less. By setting the concentration within the above upper and lower limits, the dispersibility of (B) conductive filler in thermoplastic polyester resin tends to improve.

[0044] The content of (B) conductive filler in the resin composition of this embodiment is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and may also be 1.0% by mass or more. Furthermore, it is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, and even more preferably 3% by mass or less. Setting it below the above upper limit tends to further improve the fluidity of the resin.

[0045] The resin composition of this embodiment preferably contains (B) conductive filler in an amount of 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the total amount of (A) thermoplastic resin. By setting it above the lower limit, electromagnetic wave absorption is effectively exhibited. Furthermore, the resin composition of this embodiment preferably contains 80 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 12 parts by mass or less, per 100 parts by mass of the total amount of (A) thermoplastic resin. By setting it below the upper limit, the fluidity of the resin tends to improve further. The resin composition of this embodiment may contain only one type of conductive filler (B), or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0046] <(C) Non-conductive thermal filler> The resin composition of this embodiment includes (C) a non-conductive thermal conductive filler. (C) A non-conductive thermal conductive filler is a filler that is both non-conductive and thermally conductive. In this embodiment, (C) the non-conductive thermal filler has an average particle size of 10 to 100 μm. By setting it above the lower limit, good heat dissipation paths are formed in the resulting molded product, and good thermal conductivity can be achieved. By setting it below the upper limit, the mechanical strength of the resin composition tends to improve further. In this embodiment, the (C) non-conductive thermal filler used is preferably non-fibrous. (C) The average particle size of the non-conductive thermal conductive filler is 10 μm or more, preferably 11 μm or more, more preferably 12 μm or more, preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and most preferably 20 μm or less. The aforementioned average particle diameter is the value of the volume-average particle diameter D50 measured according to the laser diffraction method (equivalent to JIS Z 8825).

[0047] In this embodiment, (C) the non-conductive thermal filler preferably includes at least one selected from the group consisting of talc, boron nitride, magnesium oxide, aluminum oxide, and silicon nitride, and more preferably talc and / or boron nitride.

[0048] The content of (C) non-conductive thermal conductive filler in the resin composition of this embodiment is 10% by mass or more, preferably 12% by mass or more, more preferably 15% by mass or more, even more preferably 18% by mass or more, and also 60% by mass or less, preferably 50% by mass or less, even more preferably 40% by mass or less, even more preferably 35% by mass or less, and even more preferably 32% by mass or less. Setting it above the lower limit tends to further improve thermal conductivity. Also, setting it below the upper limit tends to further improve the mechanical strength of the resin composition. The resin composition of this embodiment may contain only one type of (C) non-conductive thermal conductive filler, or it may contain two or more types. When two or more types are included, it is preferable that the total amount is within the above range.

[0049] In the resin composition of this embodiment, the mass ratio ((B) / (C)) of (B) conductive filler to (C) non-conductive thermal conductive filler is preferably 0.0025 or more, more preferably 0.005 or more, even more preferably 0.01 or more, even more preferably 0.015 or more, even more preferably 0.02 or more, and also preferably 3.0 or less, more preferably 1.0 or less, even more preferably 0.5 or less, even more preferably 0.2 or less, and even more preferably 0.10 or less. Setting it above the lower limit tends to improve electromagnetic wave absorption. Setting it below the upper limit tends to improve thermal conductivity.

[0050] The resin composition of this embodiment may also be substantially graphite-free. Substantially graphite-free means that the graphite content in the resin composition is less than 0.15% by mass of the resin composition, preferably less than 0.10% by mass, more preferably less than 0.07% by mass, even more preferably less than 0.05% by mass, even more preferably less than 0.03% by mass, and may be less than 0.01% by mass. The resin composition of this embodiment may also be substantially free of carbon fibers. Substantially free means that the carbon fiber content in the resin composition is less than 0.15% by mass of the resin composition, preferably less than 0.10% by mass, more preferably less than 0.07% by mass, even more preferably less than 0.05% by mass, even more preferably less than 0.03% by mass, and may be less than 0.01% by mass.

[0051] <Glass fiber> The resin composition of this embodiment may also contain glass fibers. The glass fibers consist of glass compositions such as A glass, C glass, E glass, S glass, D glass, M glass, and R glass, and E glass (alkali-free glass) is particularly preferred because it does not adversely affect the polybutylene terephthalate resin. Fibers are defined as materials that, when cut perpendicular to their length, have a circular, elliptical, or polygonal cross-sectional shape, and whose length is sufficiently long relative to their cross-sectional area, exhibiting a fibrous appearance.

[0052] The glass fibers used in the resin composition of this embodiment may be single fibers or multiple single fibers twisted together. The glass fibers can take any form, including "glass roving" (single fibers or multiple strands twisted together and wound continuously), "chopped strands" (cut to a length of 1-10 mm), or "milled fibers" (pulverized to a length of 10-500 μm), but chopped strands are preferred. Such glass fibers are commercially available from Asahi Fiber Glass Co., Ltd. under the product names "Glasslon Chopped Strands" and "Glasslon Milled Fiber," and are readily available. Different forms of glass fibers can also be used in combination.

[0053] Furthermore, in this embodiment, glass fibers having an irregular cross-sectional shape are also preferred. This irregular cross-sectional shape refers to a flattening ratio, indicated by the major axis / minor axis ratio (D2 / D1) when the major axis of the cross-section perpendicular to the length direction of the fiber is D2 and the minor axis is D1, where D2 is the major axis and D1 is the minor axis, and which is, for example, 1.5 to 10, more preferably 2.5 to 10, even more preferably 2.5 to 8, and particularly preferably 2.5 to 5. For such flattened glass, refer to paragraphs 0065 to 0072 of Japanese Patent Application Publication No. 2011-195820, and this content is incorporated herein.

[0054] If the resin composition of this embodiment contains glass fibers, the content is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more, based on 100 parts by mass of the total amount of thermoplastic resin (A). Setting it above the lower limit tends to further improve the mechanical strength of the resulting molded product. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less, based on 100 parts by mass of the total amount of thermoplastic resin (A). Setting it below the upper limit tends to improve the surface appearance of the molded product.

[0055] Furthermore, if the resin composition of this embodiment contains glass fibers, the content is preferably 10% by mass or more, preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less, and may be 35% by mass or less. Setting it above the lower limit tends to further improve the mechanical hardness of the resulting molded product. Setting it below the upper limit tends to further improve the fluidity of the resin during molding and the appearance of the resulting molded product. The resin composition of this embodiment may contain only one type of glass fiber, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0056] In the resin composition of this embodiment, the mass ratio of (B) conductive filler to glass fiber ((B) conductive filler / glass fiber) is preferably 0.01 or higher, more preferably 0.015 or higher, and even more preferably 0.02 or higher. Setting it above the lower limit tends to yield higher electromagnetic wave absorption performance. Furthermore, the mass ratio of (B) conductive filler to glass fiber is preferably 0.30 or lower, more preferably 0.20 or lower, and even more preferably 0.10 or lower. Setting it below the upper limit tends to yield higher impact strength of the resin composition.

[0057] The resin composition of this embodiment preferably contains 30% by mass or more of (B) conductive filler and (C) non-conductive thermal conductive filler, as well as glass fibers added as needed, more preferably 40% by mass or more, even more preferably 45% by mass or more, even more preferably 47% by mass or more, and also preferably 65% ​​by mass or less, more preferably 60% by mass or less, even more preferably 57% by mass or less, and even more preferably 55% by mass or less.

[0058] <Other ingredients> The resin composition of this embodiment may contain other components as needed, as long as they do not significantly impair the desired physical properties. Examples of other components include various resin additives. The other components may be present individually, or two or more in any combination and ratio.

[0059] Examples of various resin additives include stabilizers, release agents, flame retardants, flame retardant enhancers, reactive compounds, pigments, dyes, elastomers, impact resistance modifiers, sliding properties modifiers, UV absorbers, antistatic agents, antifogging agents, antiblocking agents, flowability modifiers, plasticizers, dispersants, and antibacterial agents. The resin composition of this embodiment preferably contains at least one of a stabilizer and a release agent. The resin composition of this embodiment is prepared such that the total amount of (A) thermoplastic resin, (B) conductive filler, (C) non-conductive thermal conductive filler, and other selectively blended components is 100% by mass.

[0060] The resin composition of this embodiment preferably contains (A) a thermoplastic resin, (B) a conductive filler, (C) a non-conductive thermal conductive filler, and glass fibers added as needed, with the total amount of these components being 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 97% by mass or more, and preferably 100% by mass or less.

[0061] The resin composition of this embodiment may also be configured to be substantially free of halogen-based flame retardants and / or phosphorus-based flame retardants (and even flame retardants). Substantially free means that the flame retardant content is, for example, less than 0.01 parts by mass, preferably less than 0.007 parts by mass, more preferably less than 0.005 parts by mass, even more preferably less than 0.003 parts by mass, even more preferably less than 0.001 parts by mass, and even more preferably less than 0.00001 parts by mass, based on 100 parts by mass of the total amount of (A) thermoplastic resin.

[0062] The resin composition of this embodiment may also be configured to be substantially free of reactive compounds (preferably epoxy compounds). Substantially free means that the flame retardant content is, for example, less than 1.0 part by mass, preferably less than 0.7 parts by mass, more preferably less than 0.5 parts by mass, even more preferably less than 0.3 parts by mass, even more preferably less than 0.1 parts by mass, even more preferably less than 0.01 parts by mass, and even more preferably less than 0.001 parts by mass, based on 100 parts by mass of the total amount of thermoplastic resin (A).

[0063] <<Stabilizer>> The resin composition of this embodiment may contain stabilizers. These stabilizers include those referred to as heat stabilizers, antioxidants, and light stabilizers. Examples of stabilizers include hindered phenol compounds, hindered amine compounds, phosphorus compounds, and sulfur-based stabilizers. Among these, sulfur-based, hindered phenol compounds, and phosphorus compounds are preferred. Specifically, as stabilizers, reference can be made to paragraphs 0046-0057 of Japanese Patent Publication No. 2018-070722, paragraphs 0030-0037 of Japanese Patent Publication No. 2019-056035, paragraphs 0066-0078 of International Publication No. 2017 / 038949, and paragraphs 0071-0078 of Japanese Patent Publication No. 2020-084037, the contents of which are incorporated herein by reference. Commercially available stabilizers include BASF's "Irganox 1010" and "Irganox 1076" (product names, same below), ADEKA's "ADEKA Stab AO-50", "ADEKA Stab AX-71", "ADEKA Stab AO-60", and "ADEKA Stab AO-412S".

[0064] The resin composition of this embodiment preferably contains 0.01 parts by mass or more of stabilizer per 100 parts by mass of thermoplastic resin (A), more preferably 0.05 parts by mass or more, and even more preferably 0.08 parts by mass or more. Furthermore, the upper limit of the stabilizer content 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 per 100 parts by mass of thermoplastic resin (A). The resin composition of this embodiment may contain only one stabilizer or two or more stabilizers. When two or more stabilizers are included, it is preferable that the total amount is within the above range.

[0065] <<Release agent>> The resin composition of this embodiment preferably contains a mold release agent. A wide range of known release agents can be used as the release agent, with aliphatic carboxylic acid esters, paraffin wax, polystyrene wax, and polyolefin wax being preferred, and polyethylene wax being more preferred. Specifically, as a mold release agent, reference can be given to the descriptions in paragraphs 0115 to 0120 of Japanese Patent Publication No. 2013-007058, paragraphs 0063 to 0077 of Japanese Patent Publication No. 2018-070722, and paragraphs 0090 to 0098 of Japanese Patent Publication No. 2019-123809, the contents of which are incorporated herein by reference.

[0066] The resin composition of this embodiment preferably contains 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 the mold release agent per 100 parts by mass of the thermoplastic resin (A). Furthermore, the upper limit of the mold release agent content 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, per 100 parts by mass of the thermoplastic resin (A). The resin composition may contain only one type of release agent or two or more types. If it contains two or more types, it is preferable that the total amount is within the above range.

[0067] <Physical properties of resin compositions> The resin composition of this embodiment preferably has a high electromagnetic wave absorption rate. Specifically, the resin composition of this embodiment preferably has an absorption rate of 40.0 to 100% when molded to a thickness of 2 mm (preferably 100 mm × 100 mm × 2 mm) and determined according to formula (A) at a frequency of 76.5 GHz. Formula (A)

number

[0068] The absorption rate is preferably 45.0% or higher, more preferably 50.0% or higher, even more preferably 55.0% or higher, even more preferably 60.0% or higher, even more preferably 65.0% or higher, and even more preferably 68.0% or higher. Ideally, the upper limit is 100%, but even 90.0% or lower will sufficiently satisfy the required performance.

[0069] The resin composition of this embodiment preferably has high thermal conductivity. Specifically, when the resin composition of this embodiment is molded into a flat test piece measuring 100 mm × 100 mm × 3 mm in thickness, the thermal conductivity in the planar direction is preferably 1.0% or more, more preferably 1.1% or more, and may also be 2.5% or less. Furthermore, when the resin composition of this embodiment is molded into a flat test piece measuring 100 mm × 100 mm × 3 mm in thickness, the thermal conductivity in the thickness direction is preferably 0.05% or more, more preferably 0.1% or more, and may also be 1.0% or less.

[0070] <Method for producing resin compositions> The resin composition of this embodiment can be manufactured by a conventional method for producing resin compositions containing a thermoplastic resin. For example, it can be obtained by melt-kneading a resin composition containing (A) a thermoplastic resin, (B) a conductive filler, (C) a non-conductive thermal conductive filler, and other components such as glass fibers as needed. One form formed from such a resin composition is a pellet. The components may be pre-mixed and supplied to the extruder all at once, or they may be supplied to the extruder using a feeder, either without pre-mixing the components or with only some of them pre-mixed. For example, it is preferable to side-feed the glass fibers. The extruder may be a single-screw extruder or a twin-screw extruder. Furthermore, (B) the conductive filler is preferably supplied after being master-batched with a thermoplastic resin (preferably polybutylene terephthalate resin). The heating temperature during melting and kneading can usually be appropriately selected from the range of 170 to 350°C.

[0071] <Method for manufacturing molded articles> The molded body, in particular the electromagnetic wave absorber, is formed from the resin composition or pellets of this embodiment. The method for manufacturing the molded article in this embodiment is not particularly limited, and any molding method commonly used for resin compositions containing thermoplastic resins can be arbitrarily employed. Examples include injection molding, ultra-high-speed injection molding, injection compression molding, two-color molding, hollow molding methods such as gas-assisted molding, molding using a heat-insulating mold, molding using a rapidly heated mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating) molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, etc., with injection molding being preferred among them.

[0072] <Application> The electromagnetic wave absorber of this embodiment is formed from the resin composition of this embodiment. That is, the resin composition of this embodiment is preferably for use as an electromagnetic wave absorber (also called for use as an electromagnetic wave absorbing member), more preferably for use as an electromagnetic wave absorber with a frequency of at least 60 to 90 GHz, and even more preferably for use as an electromagnetic wave absorber with a frequency of at least 70 to 80 GHz. In particular, it is preferably for use as an electromagnetic wave absorber where thermal conductivity is required. Such an electromagnetic wave absorber is preferably used in radar applications. Specifically, it is used in housings, covers, retaining parts, anti-reflective materials, etc., for millimeter-wave radar. The electromagnetic wave absorber of this embodiment can be suitably used in: on-board millimeter-wave radar used in automatic brake control devices, inter-vehicle distance control devices, pedestrian accident reduction steering devices, unintended acceleration suppression devices, pedal misapplication acceleration suppression devices, approaching vehicle warning devices, lane keeping assist devices, rear-end collision prevention warning devices, parking assist devices, vehicle surrounding obstacle warning devices, etc.; railway and aviation millimeter-wave radar used in platform monitoring / level crossing obstacle detection devices, in-train content transmission devices, tram / railway collision avoidance devices, runway foreign object detection devices, etc.; millimeter-wave radar for traffic infrastructure such as intersection monitoring devices and elevator monitoring devices; millimeter-wave radar for various security devices; medical and nursing care millimeter-wave radar such as child and elderly monitoring systems; millimeter-wave radar for various information content transmission; and the like. [Examples]

[0073] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0074] 1.Raw materials [Table 1]

[0075] 2. Examples 1-9, Comparative Examples 1-6 <Manufacturing of resin compositions (pellets)> As shown in Tables 2-5, each component other than the glass fiber listed in Table 1 (the proportion of each component is in parts by mass) was placed in a stainless steel tumbler and stirred and mixed for 1 hour. The resulting mixture was supplied from the main feed port to a coaxial twin-screw extruder (TEX-30α, manufactured by Japan Steel Works, Ltd., screw diameter 32 mm, L / D=42), and the glass fiber was supplied from a side feeder located in the middle of the extruder. The barrel temperature of the first mixing section was set to 260°C, and the barrel temperature of the second mixing section located after the side feed was set to 220°C for plasticization. Melt-kneading was performed under conditions of a discharge rate of 30 kg / h and a screw rotation speed of 250 rpm, and the mixture was extruded as strands under conditions of 5 nozzles (circular (φ4 mm), length 1.5 cm). The extruded strands were introduced into a water tank for cooling, inserted into a pelletizer, and cut to obtain resin compositions (pellets).

[0076] <76.5GHz electromagnetic wave absorption rate> The pellets obtained above were dried in a 120°C hot air oven for 6 hours, and then injection molded using an injection molding machine (Nissei Plastic Industrial Co., Ltd. "NEX80") with a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test specimens measuring 100 mm × 100 mm × 2 mm in thickness. Using the obtained test specimens, the absorptivity, which can be determined according to equation (A) at a frequency of 76.5 GHz, was measured as follows. For the measurements, we used a Keysight N5252A network analyzer. The measurements were taken when the test specimen was positioned so that the machine direction (MD) of the injection-molded body was parallel to the electric field direction. Formula (A)

number

[0077] <Thermal conductivity> The pellets obtained above were dried in a 120°C hot air oven for 6 hours, and then injection molded using an injection molding machine (Nissei Plastic Industrial Co., Ltd. "NEX80") with a cylinder temperature of 260°C and a mold temperature of 80°C to obtain a flat plate-shaped test specimen measuring 100 mm × 100 mm × 3 mm thick. The thermal conductivity of the obtained test specimen was measured in the planar direction and the thickness direction, respectively, using a Hot Disk "TPS 2500 S".

[0078] <Bending properties> The pellets obtained as described above were dried at 120°C for 6 hours, and then 4 mm thick ISO test specimens were injection molded using an injection molding machine (Japan Steel Works, Ltd. "J85AD") under the conditions of a cylinder temperature of 250°C and a mold temperature of 80°C. In accordance with ISO 178, the bending strength (in MPa) and bending modulus (in MPa) were measured at a temperature of 23°C using the above ISO tensile test specimen (4 mm thick).

[0079] [Table 2]

[0080] [Table 3]

[0081] [Table 4]

[0082] [Table 5]

[0083] As is clear from the above results, the resin composition of the present invention had a high electromagnetic wave absorption rate and excellent thermal conductivity (Examples 1-8). In particular, by incorporating an amorphous thermoplastic resin, a resin composition with a good balance of electromagnetic wave absorption rate, thermal conductivity, and flexibility was obtained (Examples 6, 7, 9). On the other hand, when conductive fillers were not included (Comparative Examples 1 and 4), the electromagnetic wave absorption rate was extremely low. Also, when non-conductive thermal conductive fillers were not included (Comparative Examples 2 and 3), the thermal conductivity was poor. On the other hand, when the material contained a large amount of graphite or carbon fiber and did not contain non-conductive thermally conductive fillers (Comparative Examples 5-6), the electromagnetic wave absorption performance was significantly impaired.

[0084] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

Claims

1. (A) A thermoplastic resin containing polyalkylene terephthalate resin, (B) Conductive filler and, (C) A resin composition comprising a non-conductive thermal conductive filler, The average particle size of the non-conductive thermal filler (C) is 10 to 100 μm. A resin composition wherein the content of (C) a non-conductive thermal conductive filler in the resin composition is 10 to 60% by mass.

2. The resin composition according to claim 1, wherein the content of (B) conductive filler in the resin composition is 0.1 to 40% by mass.

3. The resin composition according to claim 1 or 2, wherein the content of (C) non-conductive thermal conductive filler in the resin composition is 12 to 60% by mass.

4. The resin composition according to claim 1 or 2, wherein the conductive filler (B) comprises at least one selected from the group consisting of carbon nanotubes, conductive carbon black, carbon nanostructures, and graphene.

5. The resin composition according to claim 1 or 2, wherein the (C) non-conductive thermal conductive filler comprises at least one selected from the group consisting of talc, boron nitride, magnesium oxide, aluminum oxide, and silicon nitride.

6. The content of (B) conductive filler in the resin composition is 0.1 to 40% by mass. The content of (C) non-conductive thermal conductive filler in the resin composition is 12 to 60% by mass. The conductive filler (B) comprises at least one selected from the group consisting of carbon nanotubes, conductive carbon black, carbon nanostructures, and graphene. The resin composition according to claim 1, wherein the (C) nonconductive thermal conductive filler comprises at least one selected from the group consisting of talc, boron nitride, magnesium oxide, aluminum oxide, and silicon nitride.

7. Furthermore, the resin composition according to claim 1, 2, or 6, wherein the resin composition contains glass fibers in a proportion of 10 to 50% by mass.

8. The resin composition according to claim 1, 2, or 6, wherein the polyalkylene terephthalate resin comprises a polybutylene terephthalate resin.

9. The resin composition according to claim 1, 2, or 6, wherein the (A) thermoplastic resin comprises a polycarbonate resin and / or a styrene-based resin.

10. The resin composition according to claim 1, 2, or 6, wherein when the resin composition is molded to a thickness of 2 mm, the absorption rate determined according to formula (A) at a frequency of 76.5 GHz is 40.0 to 100%. Formula (A) [Math 1] (In the above formula (A), R represents the return loss measured by the free-space method, and T represents the transmission loss measured by the free-space method.)

11. The content of (B) conductive filler in the resin composition is 0.1 to 40% by mass. The content of (C) non-conductive thermal conductive filler in the resin composition is 12 to 60% by mass. The conductive filler (B) comprises at least one selected from the group consisting of carbon nanotubes, conductive carbon black, carbon nanostructures, and graphene. The (C) non-conductive thermal filler comprises at least one selected from the group consisting of talc, boron nitride, magnesium oxide, aluminum oxide, and silicon nitride. Furthermore, the resin composition contains glass fibers in a proportion of 10 to 50% by mass, The polyalkylene terephthalate resin includes polybutylene terephthalate resin, The thermoplastic resin (A) comprises a polycarbonate resin and / or a styrene-based resin. The resin composition according to claim 1, wherein when the resin composition is molded to a thickness of 2 mm, the absorption rate determined according to formula (A) at a frequency of 76.5 GHz is 40.0 to 100%. Formula (A) [Math 2] (In the above formula (A), R represents the return loss measured by the free-space method, and T represents the transmission loss measured by the free-space method.)

12. Pellets formed from the resin composition according to claim 1, 2, 6, or 11.

13. A molded article formed from the resin composition according to claim 1, 2, 6, or 11.

14. An electromagnetic wave absorber formed from the resin composition according to claim 1, 2, 6, or 11.

15. An electromagnetic wave absorber formed from the pellets described in claim 12.

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