Resin composition, molded article, and electromagnetic wave absorber

Abstract

To provide a resin composition having high absorptivity of electromagnetic waves and having high flame retardancy and fire resistance, and a molded product and an electromagnetic wave absorber.SOLUTION: A resin composition contains thermoplastic resin, reinforced fibers, carbon nanotubes, and a flame retardant. When molded into thickness of 2 mm, its absorptivity at frequency 76.5 GHz is 40.0-100%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a molded article, and an electromagnetic wave absorber. [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 millimeter-wave radar applications, there is a growing demand for materials with high electromagnetic wave absorption rates. Furthermore, even electromagnetic wave-absorbing materials require flame retardancy and heat resistance depending on the application. The present invention aims to solve these problems and to provide a resin composition, molded article, and electromagnetic wave absorber that have high electromagnetic wave absorption and excellent flame retardancy and heat resistance. [Means for solving the problem]

[0005] Based on the above problems, the inventors conducted research and found that the above problems can be solved by blending carbon nanotubes, flame retardants, and reinforcing fibers into a thermoplastic resin, and ensuring that the absorption rate is within a predetermined range.

[0006] Specifically, the above problem was solved by the following means. <1> A resin composition comprising a thermoplastic resin, reinforcing fibers, carbon nanotubes, and a flame retardant, wherein the absorption rate, when molded to a thickness of 2 mm, is 40.0 to 100% according to formula (A) at a frequency of 76.5 GHz. Formula (A)

number

Advantages of the Invention

[0007] According to the present invention, it has become possible to provide a resin composition having a high electromagnetic wave absorption rate, excellent flame retardancy and heat resistance, as well as a molded article and an electromagnetic wave absorber.

Modes for Carrying Out the Invention

[0008] Hereinafter, modes 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 to mean including the numerical values described before and after it as the lower limit value and the upper limit value. In this specification, various physical property values and characteristic values are those at 23°C unless otherwise specified. In this specification, "(meth)acrylate" means at least one of methacrylate and acrylate. In this specification, the weight average molecular weight and the number average molecular weight are polystyrene conversion values measured by the GPC (gel permeation chromatography) method unless otherwise specified. In this specification, the units of the reflection attenuation amount and the transmission attenuation amount are "dB" (decibel). When the standards shown in this specification differ depending on the year and the measurement methods, etc., they are based on the standards at the time of filing unless otherwise specified.

[0009] The resin composition of the present embodiment contains a thermoplastic resin, a reinforcing fiber, carbon nanotubes, and a flame retardant, and is characterized in that the absorption rate determined according to formula (A) at a frequency of 76.5 GHz when molded to a thickness of 2 mm is 40.0 to 100%. Formula (A)

number

[0010] Furthermore, in millimeter-wave radar, reflected electromagnetic waves, in addition to transmitted electromagnetic waves, also become noise and can cause malfunctions. Therefore, there is an increasing demand for materials with high electromagnetic wave absorption and low transmittance and reflectance. The resin composition of this embodiment is preferable because it has high electromagnetic wave absorption and low transmittance and reflectance. In addition, the resin composition of this embodiment can have high mechanical strength.

[0011] <Thermoplastic resin> The resin composition of this embodiment includes a thermoplastic resin. Examples of thermoplastic resins used in this embodiment include 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; and it is more preferable to include at least one of polyester resin, polyamide resin, polycarbonate resin, and polyphenylene ether resin, even more preferable to include polyester resin, and even more preferable to include polybutylene terephthalate resin. However, thermoplastic resins that fall under the category of brominated flame retardants described later are classified as brominated flame retardants.

[0012] In this embodiment, a preferred example of the thermoplastic resin is that it contains a polyester resin (preferably a polybutylene terephthalate resin), and that 90% or more (preferably 95% or more by mass) of the resin composition is polyester resin (preferably a polybutylene terephthalate resin). Another preferred example of the thermoplastic resin in this embodiment is that it includes a polycarbonate resin, wherein 90% or more (preferably 95% or more by mass) of the resin composition is polycarbonate resin. Another preferred example of the thermoplastic resin in this embodiment is that it contains a polyphenylene ether resin, wherein 90% or more (preferably 95% or more by mass) of the resin composition is polyphenylene ether resin. Another preferred example of the thermoplastic resin in this embodiment is that it includes a polyamide resin (preferably a xylylenediamine-based polyamide resin, as described later), and that 90% or more (preferably 95% or more by mass) of the resin composition is a polyamide resin (preferably a xylylenediamine-based polyamide resin, as described later).

[0013] The resin composition of this embodiment may also be an alloy of two or more thermoplastic resins. When two or more thermoplastic resins are blended, they usually do not completely miscible, forming a sea-island structure. Carbon nanotubes are less likely to exist in these island areas, and as a result, the region in the resin composition or electromagnetic wave absorber where carbon nanotubes exist becomes smaller, allowing various properties such as electromagnetic wave absorption to be effectively achieved even with a reduced amount of carbon nanotubes. For example, an embodiment is described in which polybutylene terephthalate resin is blended with polycarbonate resin and / or polystyrene resin.

[0014] The following are preferred blend forms for the resin composition of this embodiment. The first blend form contains 1.0 to 75 parts by mass of polycarbonate resin per 100 parts by mass of polybutylene terephthalate resin. By incorporating polycarbonate resin, the warping of the resulting molded article can be effectively suppressed. In the first blend form, preferably 90% or more by mass, more preferably 95% or more by mass, and even more preferably 99% or more by mass of the resin components contained in the resin composition consist of polybutylene terephthalate resin and polycarbonate resin. The lower limit of the polycarbonate resin content in the first blend form is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and even more preferably 50 parts by mass or more. Setting the content above the lower limit tends to reduce the amount of warping of the molded article. The upper limit of the polycarbonate resin content in the first blend form is preferably 70 parts by mass or less, and more preferably 65 parts by mass or less. Setting the content below the upper limit tends to further improve chemical resistance and hydrolysis resistance. In the first blend form, one type of polycarbonate resin may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount is within the above range.

[0015] The second blend form contains 1.0 to 60 parts by mass of polystyrene resin (preferably AS resin) per 100 parts by mass of polybutylene terephthalate resin. By incorporating polystyrene resin, the warping of the resulting molded article can be effectively suppressed. In the second blend form, preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more of the resin components contained in the resin composition consist of polybutylene terephthalate resin and polystyrene resin (preferably AS resin). The lower limit of the polystyrene resin (preferably AS resin) content in the second blend form is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more. Setting the content above the lower limit tends to reduce the amount of warping of the molded article. The upper limit of the polystyrene resin (preferably AS resin) content in the second blend form is preferably 90 parts by mass or less, and more preferably 80 parts by mass or less. Setting the content below the upper limit tends to improve the effect of chemical resistance. In the second blend form, one type of polystyrene resin may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount is within the above range.

[0016] The third blend form further includes 1.0 to 75 parts by mass of polycarbonate resin and 1.0 to 60 parts by mass of polystyrene resin (preferably HIPS) per 100 parts by mass of polybutylene terephthalate resin. By blending polystyrene resin and polycarbonate resin, the warping of the resulting molded article can be effectively suppressed. In the third blend form, preferably 90% or more by mass, more preferably 95% or more by mass, and even more preferably 99% or more by mass of the resin components contained in the resin composition consist of polybutylene terephthalate resin, polycarbonate resin and polystyrene resin (preferably HIPS).

[0017] The lower limit of the styrene resin content (preferably HIPS) in the third blend form is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, and even more preferably 38 parts by mass or more. Setting the content above the lower limit tends to reduce the amount of warping of the molded article. The upper limit of the styrene resin content in the third blend form is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, even more preferably 60 parts by mass or less, even more preferably 55 parts by mass or less, and even more preferably 50 parts by mass or less. Setting the content below the upper limit tends to improve chemical resistance. The lower limit of the polycarbonate resin content in the third blend form is preferably 4 parts by mass or more, more preferably 8 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 12 parts by mass or more. Setting the content above the lower limit tends to reduce the amount of warping of the molded article. The upper limit of the polycarbonate resin content in the third blend form is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and even more preferably 18 parts by mass or less. Setting the content below the upper limit tends to improve chemical resistance and hydrolysis resistance. In the third blend form, the mass ratio of polycarbonate resin to styrene resin is preferably 1:2.0 to 4.0, and more preferably 1:2.5 to 3.5. By using such a mass ratio, warping of the molded article is suppressed and the mechanical strength tends to be further improved. In the third blend form, styrene resin and polycarbonate resin may be used individually or in combination of two or more types. When using two or more types, it is preferable that the total amount be within the above range. The following describes the details of each thermoplastic resin.

[0018] <<Polyester resin>> As the polyester resin, known thermoplastic polyester resins can be used, with polyethylene terephthalate resin and polybutylene terephthalate resin being preferred, and more preferably containing at least polybutylene terephthalate resin. The polybutylene terephthalate resin used in the resin composition of this embodiment is a polyester resin having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded, and includes, in addition to the polybutylene terephthalate resin (homopolymer), a polybutylene terephthalate copolymer containing other copolymer components other than terephthalic acid units and 1,4-butanediol units, or a mixture of the homopolymer and the polybutylene terephthalate copolymer.

[0019] Polybutylene terephthalate resin may contain one or more dicarboxylic acid units other than terephthalic acid. Other specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, bis(4,4'-carboxyphenyl)methane, anthracenedicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4'-dicyclohexyldicarboxylic acid; and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and dimer acid. In this embodiment, the polybutylene terephthalate resin preferably contains terephthalic acid units accounting for 80 mol% or more of the total dicarboxylic acid units, and more preferably 90 mol% or more.

[0020] The diol unit may include one or more other diol units in addition to 1,4-butanediol. Other specific examples of diol units include aliphatic or alicyclic diols with 2 to 20 carbon atoms, and bisphenol derivatives. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, 4,4'-dicyclohexylhydroxymethane, 4,4'-dicyclohexylhydroxypropane, and ethylene oxide addition diols of bisphenol A. In addition to the bifunctional monomers mentioned above, small amounts of trifunctional monomers such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane can be used to introduce branched structures, and small amounts of monofunctional compounds such as fatty acids can be used to adjust molecular weight. In this embodiment, the polybutylene terephthalate resin preferably contains 1,4-butanediol units accounting for 80 mol% or more of the total diol units, and more preferably 90 mol% or more.

[0021] As described above, the polybutylene terephthalate resin is preferably a polybutylene terephthalate homopolymer obtained by polycondensation of terephthalic acid and 1,4-butanediol. Alternatively, it may be a polybutylene terephthalate copolymer containing one or more dicarboxylic acids other than terephthalic acid as the carboxylic acid unit and / or one or more diols other than 1,4-butanediol as the diol unit. When the polybutylene terephthalate resin is a polybutylene terephthalate resin modified by copolymerization, specific preferred copolymers include polyester ether resins copolymerized with polyalkylene glycols, particularly polytetramethylene glycol, dimer acid copolymerized polybutylene terephthalate resins, and isophthalic acid copolymerized polybutylene terephthalate resins. Among these, it is preferable to use a polyester ether resin copolymerized with polytetramethylene glycol. These copolymers refer to those with a copolymerization amount of 1 mol% or more and less than 50 mol% of the total segments of the polybutylene terephthalate resin. In particular, the copolymerization amount is preferably 2 mol% or more and less than 50 mol%, more preferably 3 to 40 mol%, and even more preferably 5 to 20 mol%. Such copolymerization ratios tend to improve fluidity, toughness, and tracking resistance, and are therefore preferable.

[0022] 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. Keeping it below the above upper limit tends to improve alkali resistance and hydrolysis resistance. There is no specific lower limit for the amount of terminal carboxyl groups, but considering the productivity of polybutylene terephthalate resin production, it is usually 10 eq / ton or more.

[0023] The amount of terminal carboxyl groups in polybutylene terephthalate resin is measured by dissolving 0.5 g of polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating it with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. The amount of terminal carboxyl groups can be adjusted by any conventionally known method, such as adjusting polymerization conditions like the raw material ratio, polymerization temperature, and reduced pressure method during polymerization, or by reacting with a chelating agent.

[0024] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 to 2 dL / g. From the viewpoint of moldability and mechanical properties, an intrinsic viscosity in the range of 0.6 to 1.5 dL / g is more preferable. Setting the intrinsic viscosity to 0.5 dL / g or higher tends to further improve the mechanical strength of the resulting resin composition. Conversely, setting it to 2 dL / g or lower tends to further improve the fluidity of the resin composition 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.

[0025] Polybutylene terephthalate resin can be produced by melt polymerization of a dicarboxylic acid component mainly composed of terephthalic acid or ester derivatives thereof, and a diol component mainly composed of 1,4-butanediol, in a batch or continuous manner. Furthermore, after producing a low molecular weight polybutylene terephthalate resin by melt polymerization, the degree of polymerization (or molecular weight) can be increased to a desired value by further solid-phase polymerization under a nitrogen atmosphere or reduced pressure. The polybutylene terephthalate resin is preferably obtained by a manufacturing method in which a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of 1,4-butanediol are continuously melt-polycondensed.

[0026] The catalyst used in carrying out the esterification reaction may be one of the conventionally known ones, such as titanium compounds, tin compounds, magnesium compounds, and calcium compounds. Among these, titanium compounds are particularly preferred. Specific examples of titanium compounds as esterification catalysts include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.

[0027] In addition to the above, the description in paragraphs 0013 to 0016 of Japanese Patent Publication No. 2010-174223 can be given to the polyester resin, and its contents are incorporated herein by reference.

[0028] <<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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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).

[0033] 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

[0034] 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.

[0035] <Polystyrene resin> Examples of polystyrene resins include homopolymers of styrene monomers and copolymers of styrene monomers with other copolymerizable monomers. More specifically, polystyrene resins include polystyrene resin, acrylonitrile-styrene copolymer (AS resin), 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), styrene-IPN type rubber copolymer, and other resins.

[0036] When polystyrene resin contains rubber components, the content of rubber components in the polystyrene resin is preferably 3 to 70% by mass, more preferably 5 to 50% by mass, and even more preferably 7 to 30% by mass. A rubber component content of 3% by mass or more tends to improve impact resistance, while a content of 50% by mass or less tends to improve flame retardancy, which is preferable. Furthermore, the average particle size of the rubber components is preferably 0.05 to 10 μm, more preferably 0.1 to 6 μm, and even more preferably 0.2 to 3 μm. An average particle size of 0.05 μm or more tends to improve impact resistance, while an average particle size of 10 μm or less tends to improve appearance, which is preferable.

[0037] The weight-average molecular weight of polystyrene resin is typically 50,000 or more, preferably 100,000 or more, more preferably 150,000 or more, and also typically 500,000 or less, preferably 400,000 or less, and more preferably 300,000 or less. The number-average molecular weight is typically 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and also preferably 500,000 or less, and more preferably 300,000 or less.

[0038] The melt flow rate (MFR) of polystyrene resin, measured according to JIS K7210 (temperature 200°C, load 5 kgf), is preferably 0.1 to 30 g / 10 min, and more preferably 0.5 to 25 g / 10 min. When the MFR is 0.1 g / 10 min or higher, fluidity tends to improve, and when it is 30 g / 10 min or lower, impact resistance tends to improve.

[0039] Known methods for producing such polystyrene resins include emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization.

[0040] <<Polyphenylene ether resin>> In this embodiment, a known polyphenylene ether resin can be used. For example, a polymer having a structural unit represented by the following formula in the main chain (preferably, a polymer in which the structural unit represented by the following formula occupies 90 mol% or more of all the structural units excluding the terminal groups) is exemplified. The polyphenylene ether resin may be either a homopolymer or a copolymer.

[0041]

Chemical formula

[0042] R a and R b are each independently preferably a hydrogen atom, a primary or secondary alkyl group, or an aryl group. Preferred examples of the primary alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-amyl group, an isoamyl group, a 2-methylbutyl group, a 2,3-dimethylbutyl group, a 2-, 3-, or 4-methylpentyl group, or a heptyl group. Preferred examples of the secondary alkyl group include, for example, an isopropyl group, a sec-butyl group, or a 1-ethylpropyl group. In particular, R a is preferably a primary or secondary alkyl group having 1 to 4 carbon atoms or a phenyl group. R b is preferably a hydrogen atom.

[0043] Suitable homopolymers of polyphenylene ether resins include, for example, polymers of 2,6-dialkylphenylene ethers such as poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene ether), poly(2,6-dipropyl-1,4-phenylene ether), poly(2-ethyl-6-methyl-1,4-phenylene ether), and poly(2-methyl-6-propyl-1,4-phenylene ether). Examples of copolymers include 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymers, 2,6-dimethylphenol / 2,3,6-triethylphenol copolymers, 2,6-diethylphenol / 2,3,6-trimethylphenol copolymers, 2,6-dipropylphenol / 2,3,6-trimethylphenol copolymers, and other 2,6-dialkylphenol / 2,3,6-trialkylphenol copolymers; graft copolymers obtained by graft polymerization of styrene onto poly(2,6-dimethyl-1,4-phenylene ether); and graft copolymers obtained by graft polymerization of styrene onto 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymers.

[0044] In this embodiment, poly(2,6-dimethyl-1,4-phenylene) ether and 2,6-dimethylphenol / 2,3,6-trimethylphenol random copolymers are particularly preferred as the polyphenylene ether resin. Polyphenylene ether resins with specified terminal group counts and copper content, as described in Japanese Patent Application Publication No. 2005-344065, can also be suitably used.

[0045] The polyphenylene ether resin is preferably one with an intrinsic viscosity of 0.2 to 0.8 dL / g, and more preferably 0.3 to 0.6 dL / g, measured in chloroform at 30°C. A viscosity of 0.2 dL / g or higher tends to improve the mechanical strength of the molded article, while a viscosity of 0.8 dL / g or lower tends to improve the fluidity of the resin composition, making molding easier. Alternatively, two or more polyphenylene ether resins with different intrinsic viscosities may be used in combination to achieve this viscosity range.

[0046] The method for producing the polyphenylene ether resin used in this embodiment is not particularly limited, and a known method can be employed, for example, by oxidative polymerization of a monomer such as 2,6-dimethylphenol in the presence of an amine copper catalyst. In this case, the intrinsic viscosity can be controlled to a desired range by selecting the reaction conditions. Control of the intrinsic viscosity can be achieved by selecting conditions such as polymerization temperature, polymerization time, and catalyst amount.

[0047] <<Polyamide resin>> Polyamide resins are polymers whose constituent units are acid amides obtained by ring-opening polymerization of lactams, polycondensation of aminocarboxylic acids, and polycondensation of diamines and dibasic acids. Specifically, examples include polyamides 6, 11, 12, 46, 66, 610, 612, 6I, 6 / 66, 6T / 6I, 6 / 6T, 66 / 6T, 66 / 6T / 6I, xylylenediamine-based polyamide resins (details to be described later), polytrimethylhexamethylene terephthalamide, polybis(4-aminocyclohexyl)methanedodecamamide, polybis(3-methyl-4-aminocyclohexyl)methanedodecamamide, and polyundemethylenehexahydroterephthalamide. In addition, "I" indicates the isophthalic acid component and "T" indicates the terephthalic acid component. Furthermore, as a polyamide resin, reference can be given to the description in paragraphs 0011 to 0013 of Japanese Patent Publication No. 2011-132550, which is incorporated herein by reference.

[0048] The polyamide resin used in this embodiment contains diamine-derived structural units and dicarboxylic acid-derived structural units, and it is preferable that the xylylenediamine-based polyamide resin contains at least 50 mol% of the diamine-derived structural units derived from xylylenediamine. More preferably, at least 70 mol%, even more preferably 80 mol%, even more preferably 90 mol%, and even more preferably 95 mol%, of the diamine-derived structural units of the xylylenediamine-based polyamide resin are derived from at least one of meta-xylylenediamine and para-xylylenediamine. More preferably, at least 50 mol%, more preferably 70 mol%, even more preferably 80 mol%, even more preferably 90 mol%, and even more preferably 95 mol%, of the dicarboxylic acid-derived structural units of the xylylenediamine-based polyamide resin are derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms. α,ω-linear aliphatic dibasic acids having 4 to 20 carbon atoms can be suitably used, such as adipic acid, sebacic acid, suberic acid, dodecanediic acid, and eicodionic acid, with adipic acid and sebacic acid being more preferred.

[0049] Diamines other than meta-xylylenediamine and para-xylylenediamine that can be used as raw material diamine components for xylylenediamine-based polyamide resins include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine, as well as 1,3-bis( Examples include alicyclic diamines such as aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane, as well as aromatic ring-containing diamines such as bis(4-aminophenyl) ether, paraphenylenediamine, and bis(aminomethyl)naphthalene. One or more of these can be used in combination.

[0050] Examples of dicarboxylic acid components other than the above-mentioned α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms include phthalate compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid, and isomers of naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. One or more of these can be used in combination.

[0051] The content of the thermoplastic resin (preferably polybutylene terephthalate resin) 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 45% by mass or more, and even more preferably 50% by mass or more. Setting it above the lower limit tends to further improve chemical resistance. Furthermore, the content of the thermoplastic resin (preferably polybutylene terephthalate resin) is preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less. Setting it below the upper limit tends to more effectively reduce the amount of warpage in the molded article. The resin composition of this embodiment may contain only one type of 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.

[0052] <Carbon nanotubes> The resin composition of this embodiment contains carbon nanotubes. The inclusion of carbon nanotubes allows for effective absorption of electromagnetic waves even in small amounts. Furthermore, it achieves high flame retardancy. The carbon nanotubes used in this embodiment may be single-walled carbon nanotubes, multi-walled carbon nanotubes, or a mixture, but it is preferable that they include multi-walled carbon nanotubes. Carbon materials that partially have a 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. Carbon nanotubes may be incorporated as a masterbatch, in which case the carbon nanotube content is preferably 5 to 30% by mass. Examples of resins used for the masterbatch include polyester resin (preferably polybutylene terephthalate resin).

[0053] The resin composition of this embodiment preferably contains 0.1 parts by mass or more of carbon nanotubes per 100 parts by mass of thermoplastic resin (preferably polybutylene terephthalate resin), more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and may be 1.8 parts by mass or more, even more preferably 2.0 parts by mass or more, and particularly may be 2.4 parts by mass or more. By setting it above the lower limit, electromagnetic wave absorption is effectively exhibited. Furthermore, the resin composition of this embodiment preferably contains 10.0 parts by mass or less of carbon nanotubes per 100 parts by mass of thermoplastic resin (preferably polybutylene terephthalate resin), more preferably 8.0 parts by mass or less, even more preferably 6.0 parts by mass or less, even more preferably 4.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and may be 2.5 parts by mass or less. By setting it below the upper limit, the burning time during combustion testing tends to be further shortened. The resin composition of this embodiment may contain only one type of carbon nanotube, 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.

[0054] <Flame retardant> The resin composition of this embodiment contains a flame retardant. By including a flame retardant, flame retardancy can be achieved. Examples of flame retardants include halogen-based flame retardants, phosphorus-based flame retardants (e.g., phosphinate metal salts, polyphosphate melamine), nitrogen-based flame retardants (e.g., cyanurate melamine), and metal hydroxides (e.g., magnesium hydroxide), but phosphorus-based and halogen-based flame retardants are preferred. Among phosphorus-based flame retardants, phosphinate metal salts are more preferred. Among halogen-based flame retardants, brominated flame retardants are more preferred.

[0055] When using brominated flame retardants as flame retardants, there are no specific requirements regarding the type, but brominated phthalimide, brominated poly(meth)acrylate, brominated polycarbonate, brominated epoxy, and brominated polystyrene are preferred, and brominated poly(meth)acrylate, brominated polycarbonate, and brominated epoxy are more preferred.

[0056] As the brominated phthalimide, one represented by formula (1) is preferred. [ka] (In equation (1), D represents a group consisting of two or more combinations of alkylene groups, arylene groups, -S(=O)2-, -C(=O)-, and -O-. i is an integer from 1 to 4.)

[0057] In formula (1), D represents a group consisting of two or more combinations of an alkylene group, an arylene group, -S(=O)2-, -C(=O)-, and -O-, with a preferred group consisting of an alkylene group or an arylene group and at least one of -S(=O)2-, -C(=O)-, and -O-, more preferred a group consisting of an alkylene group or an arylene group and one of -S(=O)2-, -C(=O)-, and -O-, and an even more preferred alkylene group. The group consisting of an alkylene group and an -O- group includes, for example, a combination of two alkylene groups and one -O- group (the same applies to other combinations). The alkylene group D is preferably an alkylene group having 1 to 6 carbon atoms, and more preferably a methylene group, ethylene group, propylene group, or butylene group. The arylene group is preferably a phenylene group. i is an integer between 1 and 4, and is preferably 4.

[0058] Examples of brominated phthalimides represented by formula (1) include N,N'-(bistetrabromophthalimide)ethane, N,N'-(bistetrabromophthalimide)propane, N,N'-(bistetrabromophthalimide)butane, N,N'-(bistetrabromophthalimide)diethyl ether, N,N'-(bistetrabromophthalimide)dipropyl ether, N,N'-(bistetrabromophthalimide)dibutyl ether, N,N'-(bistetrabromophthalimide)diphenylsulfone, N,N'-(bistetrabromophthalimide)diphenyl ketone, and N,N'-(bistetrabromophthalimide)diphenyl ether.

[0059] As for the brominated phthalimide, formula (1) is preferably the brominated phthalimide represented by formula (2). [ka] (In equation (2), i is an integer between 1 and 4.) i is an integer between 1 and 4, and is preferably 4.

[0060] The brominated poly(meth)acrylate is preferably a polymer obtained by polymerizing benzyl(meth)acrylate containing bromine atoms alone, copolymerizing two or more types, or copolymerizing with other vinyl monomers. The bromine atoms are attached to the benzene ring, and the number of attached atoms is preferably 1 to 5 per benzene ring, with 4 to 5 being particularly preferred.

[0061] Examples of benzyl acrylates containing a bromine atom include pentabrom benzyl acrylate, tetrabrom benzyl acrylate, tribrom benzyl acrylate, or mixtures thereof. Examples of benzyl methacrylates containing a bromine atom include methacrylates corresponding to the acrylates mentioned above.

[0062] Other vinyl monomers used for copolymerization with benzyl (meth)acrylate containing bromine atoms include, specifically, acrylic acid esters such as acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and benzyl acrylate; methacrylic acid esters such as methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and benzyl methacrylate; unsaturated carboxylic acids or their anhydrides such as styrene, acrylonitrile, fumaric acid, and maleic acid; vinyl acetate, vinyl chloride, and the like.

[0063] These are usually used in amounts equal to or less than equimolar to the benzyl (meth)acrylate containing bromine atoms, and preferably in amounts of 0.5 times the molar amount or less.

[0064] In addition, vinyl monomers such as xylene acrylate, xylene methacrylate, tetrabrom xylene acrylate, tetrabrom xylene methacrylate, butadiene, isoprene, and divinylbenzene can also be used, and these can usually be used in amounts of 0.5 times or less molar relative to benzyl acrylate or benzyl methacrylate which contains bromine atoms.

[0065] The brominated poly(meth)acrylate is preferably a polymer obtained by polymerizing a (meth)acrylate monomer containing bromine atoms, particularly benzyl (meth)acrylate, alone, copolymerizing two or more of them, or copolymerizing them with other vinyl monomers. Furthermore, the bromine atoms are attached to the benzene ring, and the number of attached atoms is preferably 1 to 5 per benzene ring, with 4 to 5 being particularly preferable.

[0066] As the brominated poly(meth)acrylate, pentabromobenzyl poly(meth)acrylate is preferred due to its high bromine content.

[0067] The molecular weight of the brominated poly(meth)acrylate is arbitrary and can be selected and determined as appropriate, but it is preferably 3,000 or more in weight-average molecular weight (Mw), more preferably 10,000 or more, even more preferably 15,000 or more, even more preferably 20,000 or more, and even more preferably 25,000 or more. Setting it above the lower limit tends to yield a molded article with higher mechanical strength. Furthermore, the upper limit of the weight-average molecular weight (Mw) is preferably 100,000 or less, more preferably 80,000 or less, even more preferably 60,000 or less, even more preferably 50,000 or less, and even more preferably 35,000 or less. Setting it below the upper limit tends to further improve the fluidity of the resin composition.

[0068] The brominated polycarbonate preferably has a free bromine content of 0.05% by mass or more, and more preferably 0.20% by mass or less. This range tends to further improve the heat resistance stability of the resin composition. The brominated polycarbonate also preferably has a chlorine atom content of 0.001% by mass or more, and more preferably 0.20% by mass or less. This range tends to further improve mold corrosion resistance during molding. The brominated polycarbonate is preferably, for example, a brominated polycarbonate obtained from brominated bisphenol A, particularly tetrabromobisphenol A. Its terminal structure may include a phenyl group, a 4-t-butylphenyl group, or a 2,4,6-tribromophenyl group, with a 2,4,6-tribromophenyl group being particularly preferred.

[0069] The average number of carbonate constituent units in brominated polycarbonate can be appropriately selected and determined, but it is preferably 2 to 30, more preferably 3 to 15, and even more preferably 3 to 10.

[0070] The molecular weight of the brominated polycarbonate is arbitrary and can be selected and determined as appropriate, but preferably, the viscosity-average molecular weight is 1,000 to 20,000, and more preferably, 2,000 to 10,000.

[0071] The brominated polycarbonate obtained from the above-mentioned brominated bisphenol A can be obtained, for example, by a conventional method of reacting brominated bisphenol with phosgene. Examples of end-capping agents include aromatic monohydroxy compounds, which may be substituted with halogens or organic groups.

[0072] As brominated epoxy compounds, preferred examples include bisphenol A type brominated epoxy compounds, such as tetrabromobisphenol A epoxy compounds and glycidyl brominated bisphenol A epoxy compounds.

[0073] The molecular weight of the brominated epoxy compound is arbitrary and can be appropriately selected and determined, but it is preferably 3,000 or more in weight-average molecular weight (Mw), more preferably 10,000 or more, even more preferably 13,000 or more, even more preferably 15,000 or more, and even more preferably 18,000 or more. Setting it above the lower limit tends to yield molded articles with higher mechanical strength. Furthermore, the upper limit of the weight-average molecular weight (Mw) is preferably 100,000 or less, more preferably 80,000 or less, even more preferably 78,000 or less, even more preferably 75,000 or less, and even more preferably 70,000 or less. Setting it below the upper limit tends to further improve the fluidity of the resin composition. The brominated epoxy compound preferably has an epoxy equivalent of 3,000 to 40,000 g / eq, more preferably 4,000 to 35,000 g / eq, and particularly preferably 10,000 to 30,000 g / eq.

[0074] Furthermore, brominated epoxy oligomers can also be used in combination as brominated epoxy. In this case, for example, by using oligomers with an Mw of 5,000 or less in a proportion of about 50% by mass or less, flame retardancy, mold release properties, and fluidity can be appropriately adjusted. The bromine atom content in the brominated epoxy compound is arbitrary, but in order to impart sufficient flame retardancy, it is usually 10% by mass or more, more preferably 20% by mass or more, and especially preferably 30% by mass or more, with an upper limit of 60% by mass, and more preferably 55% by mass or less.

[0075] Preferably, the brominated polystyrene is a brominated polystyrene containing the constituent unit shown in formula (3). [ka] (In equation (3), t is an integer between 1 and 5, and n is the number of constituent units.)

[0076] Brominated polystyrene may be produced by either brominating polystyrene or by polymerizing brominated styrene monomer, but polymerized brominated styrene is preferred because it contains a small amount of free bromine (atoms). In formula (3), the CH group to which brominated benzene is bonded may be substituted with a methyl group. Brominated polystyrene may also be a copolymer obtained by copolymerizing other vinyl monomers. Examples of vinyl monomers in this case include styrene, α-methylstyrene, (meth)acrylonitrile, methyl (meth)acrylate, butadiene, and vinyl acetate. Brominated polystyrene may also be used as a single substance or a mixture of two or more substances with different structures, and may contain units derived from styrene monomers with different numbers of bromine atoms in a single molecular chain.

[0077] Specific examples of brominated polystyrene include, for example, poly(4-bromostyrene), poly(2-bromostyrene), poly(3-bromostyrene), poly(2,4-dibromostyrene), poly(2,6-dibromostyrene), poly(2,5-dibromostyrene), poly(3,5-dibromostyrene), poly(2,4,6-tribromostyrene), poly(2,4,5-tribromostyrene), poly(2,3,5-tribromostyrene), and poly(4-bromo-α-methylstyrene). Examples include poly(2,4-dibromo-α-methylstyrene), poly(2,5-dibromo-α-methylstyrene), poly(2,4,6-tribromo-α-methylstyrene), and poly(2,4,5-tribromo-α-methylstyrene), with poly(2,4,6-tribromostyrene), poly(2,4,5-tribromostyrene), and polydibromostyrene and polytribromostyrene containing an average of 2 to 3 bromine groups in the benzene ring being particularly preferred.

[0078] The brominated polystyrene preferably has an average degree of polymerization (n) of 30 to 1,500, more preferably 150 to 1,000, and particularly preferably 300 to 800. If the average degree of polymerization is less than 30, blooming is likely to occur, while if it exceeds 1,500, dispersion problems are likely to occur, and mechanical properties tend to deteriorate. Furthermore, the weight-average molecular weight (Mw) of the brominated polystyrene is preferably 5,000 to 500,000, more preferably 10,000 to 500,000, even more preferably 10,000 to 300,000, even more preferably 10,000 to 100,000, and even more preferably 10,000 to 70,000. In particular, for the brominated polystyrene mentioned above, the weight-average molecular weight (Mw) is preferably 50,000 to 70,000, and for brominated polystyrene produced by polymerization, the weight-average molecular weight (Mw) is preferably around 10,000 to 30,000. The weight-average molecular weight (Mw) can be determined as a value converted to standard polystyrene by GPC measurement.

[0079] The bromine concentration in the brominated flame retardant is preferably 45% by mass or more, more preferably 48% by mass or more, and even more preferably 50% by mass or more. Setting it above the lower limit tends to effectively improve the flame retardancy of the molded article. The upper limit of the bromine concentration is preferably 75% by mass or less, more preferably 73% by mass or less, and even more preferably 71% by mass or less.

[0080] When using a phosphinate metal salt as a flame retardant, there are no specific requirements regarding its type, but it is preferable that the phosphinate metal salt has an anion portion represented by formula (4) or (5), and the cation portion is composed of one of the following metal ions: calcium, magnesium, aluminum, or zinc.

[0081] [ka] (In the formula, R 1 and R 2 Each of these independently represents an alkyl group having 1 to 6 carbon atoms or an aryl group which may have substituents, and R 1 They may be the same or different, R 3 R represents an alkylene group having 1 to 10 carbon atoms, an arylene group which may have substituents, or a group consisting of a combination thereof. 3 The terms can be identical or different, and n represents an integer between 0 and 2. The optionally substituted aryl group is preferably an optionally substituted phenyl group. If substituted, an alkyl group having 1 to 3 carbon atoms is preferred. It is also preferable that the group be unsubstituted. The optionally substituted arylene group is preferably an optionally substituted phenylene group. The optionally substituted arylene group is preferably unsubstituted or has a C1-C3 alkyl group (preferably a methyl group) as a substituent. In this embodiment, a metal phosphinate represented by formula (5) is preferred. In this embodiment, aluminum phosphinate is also preferred.

[0082] Specific examples of phosphinate metal salts include calcium dimethylphosphinate, magnesium dimethylphosphinate, aluminum dimethylphosphinate, zinc dimethylphosphinate, calcium ethylmethylphosphinate, magnesium ethylmethylphosphinate, aluminum ethylmethylphosphinate, zinc ethylmethylphosphinate, calcium diethylphosphinate, magnesium diethylphosphinate, aluminum diethylphosphinate, zinc diethylphosphinate, calcium methyl-n-propylphosphinate, magnesium methyl-n-propylphosphinate, aluminum methyl-n-propylphosphinate, zinc methyl-n-propylphosphinate, calcium methanedi(methylphosphinate), Examples include magnesium methanedi(methylphosphinate), aluminum methanebis(methylphosphinate), zinc methanebis(methylphosphinate), calcium benzene-1,4-bis(methylphosphinate), magnesium benzene-1,4-bis(methylphosphinate), aluminum benzene-1,4-bis(methylphosphinate), zinc benzene-1,4-bis(methylphosphinate), calcium methylphenylphosphinate, magnesium methylphenylphosphinate, aluminum methylphenylphosphinate, zinc methylphenylphosphinate, calcium diphenylphosphinate, magnesium diphenylphosphinate, aluminum diphenylphosphinate, and zinc diphenylphosphinate. Details of phosphinate metal salts can be found in paragraphs 0052-0058 of International Publication No. 2010 / 010669, which are incorporated herein by reference.

[0083] The flame retardant content in the resin composition of this embodiment is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, even more preferably 5.0 parts by mass or more, even more preferably 7.0 parts by mass or more, and even more preferably 10.0 parts by mass or more, per 100 parts by mass of thermoplastic resin. Setting the content above the lower limit tends to further improve the flame retardancy of the resulting molded article. The upper limit of the flame retardant content is preferably 70.0 parts by mass or less, more preferably 60.0 parts by mass or less, even more preferably 50.0 parts by mass or less, even more preferably 45.0 parts by mass or less, even more preferably 40.0 parts by mass or less, and even more preferably 30.0 parts by mass or less, per 100 parts by mass of thermoplastic resin. Setting the content below the upper limit can more effectively suppress the decrease in the mechanical strength of the resulting molded article. The resin composition of this embodiment may contain only one type of flame retardant, 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.

[0084] <Flame retardant additive> The resin composition of this embodiment may contain a flame retardant additive. Including a flame retardant additive can further improve the flame retardancy of the molded article. The flame retardant additive is particularly preferably used when a halogen-based flame retardant is included. Examples of flame retardant additives used in this embodiment include antimony compounds, such as antimony trioxide (Sb2O3), antimony pentoxide (Sb2O5), and sodium antimonate. Antimony oxide, and especially antimony trioxide, is particularly preferred from the viewpoint of impact resistance. When a flame retardant is included, it may be included as a masterbatch. The antimony compound content in the masterbatch is preferably 30 to 90% by mass, more preferably 40 to 85% by mass, and even more preferably 50 to 85% by mass. If the resin composition of this embodiment contains a flame retardant additive (for example, an antimony compound), the content is preferably 0.1 parts by mass or more, more preferably 1.0 part by mass or more, even more preferably 2.0 parts by mass or more, and even more preferably 3.0 parts by mass or more, per 100 parts by mass of the thermoplastic resin. Setting the content above the lower limit tends to more effectively exhibit flame retardancy. Furthermore, the upper limit of the antimony compound content is preferably 20.0 parts by mass or less, more preferably 15.0 parts by mass or less, even more preferably 10.0 parts by mass or less, even more preferably 8.0 parts by mass or less, and even more preferably 7.0 parts by mass or less, per 100 parts by mass of the thermoplastic resin. Setting the content below the upper limit tends to improve the release properties and impact resistance of the resulting molded article. The resin composition of this embodiment may contain only one flame retardant (e.g., an antimony compound) or two or more. When two or more are included, it is preferable that the total amount is within the above range.

[0085] <Reinforced Fiber> The resin composition of this embodiment may contain reinforcing fibers. By including reinforcing fibers, the mechanical strength of the resulting molded article can be improved. Furthermore, the flame retardancy can also be improved. The reinforcing fibers may be short fibers or long fibers. When the reinforcing fibers are long fibers, examples of reinforcing fibers include so-called UD (Uni-Directional) long fibers, sheet-like long fibers such as woven and knitted fabrics, etc. When using these long fibers, the components of the resin composition of this embodiment other than the reinforcing fibers can be impregnated into the sheet-like long fibers to form a sheet-like resin composition (for example, a prepreg).

[0086] The raw materials for reinforcing fibers include inorganic materials such as glass, carbon (carbon fiber, etc.), alumina, boron, ceramics, and metals (steel, etc.), and organic materials such as plants (including kenaf and bamboo), aramid, polyoxymethylene, aromatic polyamide, poly(p-phenylenebenzobisoxazole), and ultra-high molecular weight polyethylene, with glass being preferred.

[0087] The resin composition of this embodiment preferably contains glass fibers as reinforcing fibers. The glass fibers are selected from glass compositions such as A glass, C glass, E glass, R glass, D glass, M glass, and S glass, with E glass (alkali-free glass) being particularly preferred. Glass fibers refer to fibrous materials whose cross-sectional shape, when cut perpendicular to the length, is circular or polygonal. Glass fibers typically have a number-average fiber diameter of 1 to 25 μm, preferably 5 to 17 μm. A number-average fiber diameter of 1 μm or more tends to improve the moldability of the resin composition. A number-average fiber diameter of 25 μm or less tends to improve the appearance of the resulting molded article and enhance its reinforcing effect. Glass fibers may be single fibers or multiple single fibers twisted together. The glass fibers may take any form, such as glass roving made by continuously winding single fibers or multiple strands twisted together, chopped strands cut to a length of 1 to 10 mm (i.e., glass fibers with a number-average fiber length of 1 to 10 mm), or milled fibers crushed to a length of approximately 10 to 500 μm (i.e., glass fibers with a number-average fiber length of 10 to 500 μm), but chopped strands cut to a length of 1 to 10 mm are preferred. Glass fibers with different forms can also be used in combination. Furthermore, glass fibers having an irregular cross-sectional shape are also preferred. This irregular cross-sectional shape refers to a flattening ratio, which is indicated by the major axis / minor axis ratio of the cross-section perpendicular to the length direction of the fiber, and 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.

[0088] The glass fibers may be surface-treated with, for example, silane compounds, epoxy compounds, or urethane compounds, or oxidized, in order to improve their affinity with the resin components, as long as the properties of the resin composition of this embodiment are not significantly impaired.

[0089] The resin composition of this embodiment preferably contains 10 parts by mass or more of reinforcing fibers (preferably glass fibers) per 100 parts by mass of thermoplastic resin (preferably polybutylene terephthalate resin), more preferably 20 parts by mass or more, even more preferably 35 parts by mass or more, and even more preferably 47 parts by mass or more. Setting the amount above the lower limit tends to further increase the mechanical strength of the resulting molded article. Furthermore, the content of the reinforcing fibers (preferably glass fibers) is preferably 100 parts by mass or less per 100 parts by mass of thermoplastic resin (preferably polybutylene terephthalate resin), more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, even more preferably 80 parts by mass or less, and even more preferably 75 parts by mass or less. Setting the amount below the upper limit tends to improve the appearance of the molded article and further improve the fluidity of the resin composition.

[0090] The content of reinforcing fibers (preferably glass fibers) in the resin composition of this embodiment is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 25% by mass or more. Furthermore, the content of the reinforcing fibers (preferably glass fibers) is more preferably 50% by mass or less, even more preferably 45% by mass or less, even more preferably 40% by mass or less, and even more preferably 35% by mass or less. Setting the content above the lower limit tends to further increase the mechanical strength. Furthermore, setting the content below the upper limit tends to improve the appearance of the molded article and further improve the fluidity of the molten resin. The resin composition of this embodiment may contain only one type of reinforcing fiber (preferably 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.

[0091] <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. Specifically, examples include reactive compounds, stabilizers, release agents, reinforcing materials other than reinforcing fibers, anti-dripping agents, pigments, dyes, UV absorbers, antistatic agents, anti-fogging agents, anti-blocking agents, flow improvers, 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 so that the total of the thermoplastic resin (preferably polybutylene terephthalate resin), carbon nanotubes, flame retardant, and reinforcing fibers, as well as other selectively blended components, amounts to 100% by mass. In the resin composition of this embodiment, it is preferable that the total of the thermoplastic resin (preferably polybutylene terephthalate resin), carbon nanotubes, flame retardant, and reinforcing fibers (preferably glass fibers) accounts for 95% by mass or more of the resin composition. Furthermore, in the resin composition of this embodiment, it is preferable that the total of the thermoplastic resin (preferably polybutylene terephthalate resin), carbon nanotubes, flame retardant, reinforcing fibers (preferably glass fibers), stabilizer, release agent, and reactive compound (preferably epoxy compound) accounts for 99% by mass or more of the resin composition.

[0092] <<Reactive Compounds>> The resin composition of this embodiment preferably contains a reactive compound. The inclusion of a reactive compound improves mechanical strength and provides a resin composition with excellent hydrolysis resistance. The reactive compound in this embodiment does not contain bromine. The reactive compound used in this embodiment preferably includes at least one selected from the group consisting of compounds having an epoxy group, carbodiimide compounds, compounds having an oxazoline group, and compounds having an oxazine group, and more preferably includes a compound having an epoxy group.

[0093] Compounds having epoxy groups are compounds having one or more epoxy groups in a single molecule, and examples include glycidyl compounds, aromatic ring-containing compounds having epoxy groups, and alicyclic compounds having epoxy groups. It is preferable that the compound contains at least one aromatic ring-containing compound having epoxy groups.

[0094] Specific examples of epoxy group-containing compounds include bisphenol A type epoxy compounds (including bisphenol A diglycidyl ether), bisphenol F type epoxy compounds (including bisphenol F diglycidyl ether), biphenyl type epoxy compounds (including bis(glycidyloxy)biphenyl), resorcinol type epoxy compounds (including resorcinol diglycidyl ether), novolac type epoxy compounds, epoxy compounds containing aromatic rings such as glycidyl benzoate, diglycidyl terephthalate, and diglycidyl orthophthalate, methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, decyl glycidyl ether, and stearyl glycidyl ether. Examples include (di)glycidyl ethers such as methyl phenyl glycidyl ether, butylphenyl glycidyl ether, allyl glycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, and propylene glycol diglycidyl ether; paraffinic (e.g., saturated fatty acid) or olefinic (e.g., unsaturated fatty acid) (di)glycidyl esters such as glycidyl sorbate, diglycidyl adipic acid, epoxidized linseed oil, and epoxidized soybean oil; alicyclic epoxy compounds such as vinylcyclohexene dioxide and dicyclopentadiene oxide; and epoxy-modified styrene-acrylic copolymers. Among these, styrene-acrylic copolymers containing glycidyl groups in the side chain, bisphenol A type epoxy compounds, novolac type epoxy compounds, bisphenol F type epoxy compounds, and biphenyl type epoxy compounds are preferred, with bisphenol A type epoxy compounds being more preferred.

[0095] The content of the reactive compound (preferably a compound having an epoxy group) in the resin composition of this embodiment is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and even more preferably 0.8 parts by mass or more, per 100 parts by mass of the thermoplastic resin (preferably polybutylene terephthalate resin). Setting it above the lower limit tends to further improve hydrolysis resistance. Furthermore, the content of the reactive compound (preferably a compound having an epoxy group) is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and even more preferably 2.0 parts by mass or less, per 100 parts by mass of the thermoplastic resin (preferably polybutylene terephthalate resin). Setting it below the upper limit tends to further stabilize the melt viscosity and improve moldability. The resin composition of this embodiment may contain only one reactive compound or two or more. When it contains two or more, it is preferable that the total amount is within the above range.

[0096] <<Stabilizer>> The resin composition of this embodiment may contain a stabilizer. Examples of stabilizers include hindered phenol compounds, hindered amine compounds, phosphorus compounds, and sulfur-based stabilizers. Among these, hindered phenol compounds are preferred. It is also preferable to use a combination of hindered phenol compounds and phosphorus compounds. 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, and paragraphs 0066-0078 of International Publication No. 2017 / 038949, the contents of which are incorporated herein by reference.

[0097] 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, 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. 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.

[0098] <<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.

[0099] The resin composition of this embodiment preferably contains 0.01 parts by mass or more of a release agent per 100 parts by mass of thermoplastic resin, more preferably 0.08 parts by mass or more, and even more preferably 0.2 parts by mass or more. Furthermore, the upper limit of the 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 thermoplastic resin. 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.

[0100] The resin composition of this embodiment may contain one or more carbon-based electromagnetic wave absorbing materials other than carbon nanotubes, or it may not contain any. The resin composition of this embodiment preferably contains no carbon-based electromagnetic wave absorbing material other than carbon nanotubes, or contains it in an amount of less than 3% by mass of the resin composition. By adopting such a configuration, the frequency dependence of the electromagnetic wave reflectivity tends to be further improved. The content of carbon-based electromagnetic wave absorbing materials other than the carbon nanotubes is preferably less than 2% by mass, more preferably less than 1% by mass, even more preferably less than 0.5% by mass, even more preferably less than 0.1% by mass, even more preferably less than 0.05% by mass, and even more preferably less than 0.01% by mass.

[0101] The resin composition of this embodiment preferably contains no carbon fibers or has a carbon fiber content of less than 3% by mass. Such a configuration tends to improve the frequency dependence of the electromagnetic wave reflectivity. Furthermore, it allows for a lower electromagnetic wave reflectivity. The carbon fiber content is preferably less than 2% by mass, more preferably less than 1% by mass, even more preferably less than 0.5% by mass, even more preferably less than 0.1% by mass, even more preferably less than 0.05% by mass, and even more preferably less than 0.01% by mass.

[0102] The resin composition of this embodiment preferably contains no graphite or has a graphite content of less than 3% by mass. Such a configuration tends to improve the frequency dependence of the electromagnetic wave reflectivity. Furthermore, it allows for a higher electromagnetic wave absorption rate. Additionally, it can further improve the mechanical strength of the resulting molded article. The graphite content is preferably less than 2% by mass, more preferably less than 1% by mass, even more preferably less than 0.5% by mass, even more preferably less than 0.1% by mass, even more preferably less than 0.05% by mass, and even more preferably less than 0.01% by mass.

[0103] The resin composition of this embodiment preferably contains no carbon black or has a carbon black content of less than 3% by mass. Such a configuration tends to improve the frequency dependence of the electromagnetic wave reflectivity. Furthermore, it can improve the mechanical strength of the resulting molded article. The carbon black content is preferably less than 2% by mass, more preferably less than 1% by mass, even more preferably less than 0.5% by mass, even more preferably less than 0.1% by mass, even more preferably less than 0.05% by mass, and even more preferably less than 0.01% by mass.

[0104] The resin composition of this embodiment preferably does not contain Ketjenblack, or has a Ketjenblack content of less than 3% by mass. Such a configuration tends to improve the frequency dependence of the electromagnetic wave reflectivity. Furthermore, it can improve the mechanical strength of the resulting molded article. The Ketjenblack content is preferably less than 2% by mass, more preferably less than 1% by mass, even more preferably less than 0.5% by mass, even more preferably less than 0.1% by mass, even more preferably less than 0.05% by mass, and even more preferably less than 0.01% by mass.

[0105] The resin composition of this embodiment may contain flame retardants other than brominated flame retardants (for example, phosphorus-based flame retardants), but it is preferable that it is substantially free of flame retardants other than brominated flame retardants. Substantially free means that the content of flame retardants other than brominated flame retardants is 10% by mass or less of the content of brominated flame retardants, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. Another embodiment of the resin composition of this embodiment is one that is substantially free of flame retardants other than metal phosphinate salts (for example, halogenated flame retardants). Substantially free means that the content of flame retardants other than metal phosphinate salts is 10% by mass or less of the content of metal phosphinate salts, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0106] <Physical properties of resin compositions> The resin composition of this embodiment preferably has excellent flame retardancy. Specifically, the resin composition of this embodiment is molded into a test piece with a thickness of 0.8 mm, and it is preferable that the flame retardancy rating according to the UL94 combustion test is V-0 or V-1, and more preferably V-0.

[0107] The resin composition of this embodiment has electromagnetic wave absorbing properties. Specifically, the resin composition of this embodiment has an absorption rate of 40.0 to 100% when molded to a thickness of 2 mm (for example, 100 mm x 100 mm x 2 mm), as determined by formula (A) at a frequency of 76.5 GHz. Formula (A)

number

[0108] The absorption rate is preferably 50.0% or higher, more preferably 55.0% or higher, even more preferably 60.0% or higher, and even more preferably 65.0% or higher. Ideally, the upper limit is 100%, but even 90.0% or lower will sufficiently satisfy the required performance.

[0109] The resin composition of this embodiment preferably has a low reflectivity of electromagnetic waves. Specifically, the resin composition of this embodiment preferably has a reflectance of 40.0% or less when molded to a thickness of 2 mm (for example, 100 mm × 100 mm × 2 mm) and determined according to formula (B) at a frequency of 76.5 GHz. Formula (B)

number

[0110] The reflectance is preferably 35.0% or less, more preferably 30.0% or less, even more preferably less than 30.0%, and even more preferably 25.0% or less. The lower limit is ideally 0%, but even 1.0% or more will sufficiently satisfy the required performance.

[0111] The resin composition of this embodiment preferably has low transmittance. The resin composition of this embodiment preferably has a transmittance of 25.0% or less when molded to a thickness of 2 mm (for example, 100 mm × 100 mm × 2 mm), as determined by formula (C) at a frequency of 76.5 GHz. Formula (C)

number

[0112] The transmittance is preferably less than 25.0%, more preferably less than 20.0%, even more preferably 19.0% or less, even more preferably less than 10.0%, and may be 8.0% or less, or even 5.0% or less. The lower limit is ideally 0%, but even 0.5% or more will sufficiently satisfy the required performance.

[0113] The test specimens used to measure the absorption, reflectance, and transmittance will yield substantially the same values ​​even if they are 150 mm × 150 mm × 2 mm in size. The resin composition of this embodiment preferably satisfies at least two of the following conditions: the absorptivity determined according to formula (A), the reflectivity determined according to formula (B), and the transmittance determined according to formula (C), and more preferably satisfies all of them.

[0114] The resin composition of this embodiment preferably has excellent tensile properties. Specifically, when the resin composition of this embodiment is molded into an ISO multipurpose test specimen (4 mm thick), the maximum tensile strength measured according to ISO 527-1 and ISO 527-2 is preferably 100 MPa or higher, and more preferably 110 MPa or higher. There is no particular upper limit for the maximum tensile strength, but for example, even 200 MPa or less is at a practical level. Furthermore, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (4 mm thick), the tensile modulus measured according to ISO 527-1 and ISO 527-2 is preferably 6,000 MPa or higher, more preferably 7,000 MPa or higher, even more preferably 8,000 PMa or higher, and may be 9,000 MPa or higher. There is no specific upper limit for the tensile modulus, but for example, 14,000 MPa or less is practical. Furthermore, when the resin composition of this embodiment is molded into an ISO multipurpose test specimen (4 mm thick), the tensile strain measured according to ISO 527-1 and ISO 527-2 is preferably 4.0% or less, more preferably 3.5% or less, and even more preferably 3.0% or less. While there is no specific lower limit for the tensile strain, for example, 1.0% or more is practical.

[0115] The resin composition of this embodiment preferably has excellent bending properties. Specifically, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (4 mm thick), the flexural strength is preferably 150 MPa or higher, and more preferably 160 MPa or higher. Furthermore, there is no upper limit to the flexural strength, but for example, 280 MPa or less is practical. Furthermore, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (4 mm thick), the flexural modulus is preferably 6,000 MPa or higher, more preferably 7,000 MPa or higher, even more preferably 8,000 MPa or higher, and may be 9,000 MPa or higher. While there is no specific upper limit for the flexural modulus, for example, 16,000 MPa or less is practical.

[0116] The resin composition of this embodiment preferably has excellent impact resistance. Specifically, when the resin composition of this embodiment is molded into an ISO tensile test specimen (4 mm thick), the notched Charpy impact strength according to ISO 179 standard is 5.0 kJ / m². 2 Preferably, it is 6.0 kJ / m 2 It is more preferable that the above values ​​are met. There is no specific upper limit for the notched Charpy impact strength, but for example, 20.0 kJ / m 2 The following, and furthermore, 12.0 kJ / m³ 2 The following is also acceptable.

[0117] The resin composition of this embodiment also has a surface resistance of 1.0 × 10⁻¹⁰ when molded to 100 mm × 100 mm × 2 mm, in accordance with IEC60093. 11 It is preferable that it be Ω or greater, and also 1.0 × 10 16 It is preferable that the value is less than or equal to Ω. The resin composition of this embodiment further has a volume resistivity of 1.0 × 10⁻¹⁰ when molded to 100 mm × 100 mm × 2 mm, in accordance with IEC60093. 10 It is preferable that the density is Ω·cm or greater, and also 1.0 × 10 17 It is preferable that the value is Ω·cm or less.

[0118] The resin composition of this embodiment preferably has excellent heat resistance. Specifically, the resin composition of this embodiment preferably has a load deflection temperature of 120°C or higher, more preferably 150°C or higher, and even more preferably 180°C or higher, at a load of 1.80 MPa as measured according to ISO 75-1 and 75-2. There is no particular upper limit for the load deflection temperature, but 230°C or lower is practical. The details of the various measurement methods described above are measured according to the examples.

[0119] <Method for producing resin compositions> The resin composition of this embodiment can be manufactured by a conventional method for manufacturing resin compositions containing a thermoplastic resin. For example, it can be manufactured by putting a thermoplastic resin (preferably polybutylene terephthalate resin), carbon nanotubes, a flame retardant, reinforcing fibers, and other components as needed into an extruder and melt-kneading them together. 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 them, or with only some of them pre-mixed. The extruder may be a single-screw extruder or a twin-screw extruder. In addition, some components such as carbon nanotubes may be melt-kneaded with a resin component (e.g., polybutylene terephthalate resin) to prepare a masterbatch, and then the remaining components may be added to this and melt-kneaded. Furthermore, it is preferable to supply the reinforcing fibers (for example, glass fibers) from a side feeder located in the middle of the extruder cylinder. The heating temperature during melting and kneading can usually be appropriately selected from the range of 170 to 350°C.

[0120] <Method for manufacturing molded articles> The method for manufacturing the molded article 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 insulated molds, molding using rapidly heated molds, foam molding (including supercritical fluids), 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 these.

[0121] <Application> The molded article of this embodiment is formed from the resin composition of this embodiment. 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. Such an electromagnetic wave absorber is preferably used in radar applications. Specifically, it is used in housings, covers, 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]

[0122] 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.

[0123] raw material The following raw materials were used. In the table below, PBT refers to polybutylene terephthalate resin. [Table 1]

[0124] Examples 1-5, Comparative Examples 1-5 <Manufacturing of resin compositions (pellets)> As shown in Tables 2 and 3, each component 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). The barrel temperature of the first kneading section was set to 260°C for plasticization, and reinforcing fibers (glass fibers) were supplied from the side feeder in the proportions shown in Table 2 or 3. After adding the reinforcing fibers, the barrel temperature was set to 250°C, and the mixture was melt-kneaded under conditions of a discharge rate of 40 kg / h and a screw rotation speed of 200 rpm. The mixture was then extruded as strands using 4 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).

[0125] <Flammable Test UL94 Rating> The pellets obtained above were dried at 120°C for 5 hours, and then injection molded using an injection molding machine (Japan Steel Works, Ltd. "J50") with a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test specimens measuring 125 mm × 13 mm × 0.8 mm in thickness. Using the obtained test specimens, the dripping during combustion and burning time were measured and evaluated based on the UL94 flammability test.

[0126] <Tensile properties> The resin pellets obtained above were dried at 120°C for 5 hours, and then ISO multipurpose test specimens (4 mm thick) 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. Using molded multi-purpose ISO test specimens, the maximum point tensile strength (in MPa), tensile modulus (in MPa), and tensile strain (in %) were measured in accordance with ISO 527-1 and ISO 527-2.

[0127] <Bending properties> The resin pellets obtained above were dried at 120°C for 5 hours, and then ISO multipurpose test specimens (4 mm thick) 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. Using molded multi-purpose ISO test specimens, flexural strength (in MPa) and flexural modulus (in MPa) were measured in accordance with ISO 178.

[0128] <Charpy impact strength with notch> The pellets obtained by the above manufacturing method were dried at 120°C for 5 hours, and then ISO tensile test specimens (4 mm thick) were injection molded using an injection molding machine (Japan Steel Works, Ltd. "J85AD") under conditions of cylinder temperature of 250°C and mold temperature of 80°C. In accordance with the ISO 179 standard, the ISO multipurpose test specimens obtained above were cut to the specified size and shape, and the Charpy impact strength (with notch) was measured. The unit is kJ / m 2 As shown.

[0129] <Absorption rate, transmittance, reflectance> Using the pellets obtained above, injection molding was performed using an injection molding machine (NEX80, manufactured by Nissei Plastic Industrial Co., Ltd.) 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 determined according to equation (A), the reflectivity determined according to equation (B), and the transmittance determined according to equation (C) at a frequency of 76.5 GHz were measured as follows. For the measurements, we used a Keysight N5252A network analyzer. Furthermore, the test specimen was positioned so that the transverse direction (TD) of the injection-molded body was parallel to the direction of the electric field, and measurements were taken. Formula (A)

number

[0130] Formula (B)

number

[0131] Formula (C)

number

[0132] <Electromagnetic wave absorption performance assessment> Electromagnetic wave absorption performance was evaluated based on absorption rate, reflectance, and transmittance. A rating was given if all three conditions were met; B if at least the absorption rate met the following criteria (excluding cases that fall under A); and C for all other conditions (neither A nor B). Judgment criteria Absorption rate of 50.0% or higher Reflectance less than 30.0% Transmittance is less than 25.0%

[0133] <Surface resistance> Using the pellets obtained above, injection molding was performed using an injection molding machine (NEX80, manufactured by Nissei Plastic Industrial Co., Ltd.) with a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test specimens measuring 100 mm x 100 mm x 2 mm in thickness. The surface resistance (in Ω) of the obtained test specimens was measured in accordance with IEC60093. For the measurements, we used the ADVANTEST R8340 ULTRA HIGH RESISTANCE METER.

[0134] <Volume Resistivity> Using the pellets obtained above, injection molding was performed using an injection molding machine (NEX80, manufactured by Nissei Plastic Industrial Co., Ltd.) with a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test specimens measuring 100 mm x 100 mm x 2 mm in thickness. The volume resistivity (unit: Ω·cm) was measured using the obtained test specimens in accordance with IEC60093. For the measurements, we used the ADVANTEST R8340 ULTRA HIGH RESISTANCE METER.

[0135] <Temperature of deflection under load> Using the ISO multipurpose test specimen (4 mm thick) obtained above, the temperature of deflection under load (unit: °C) was measured under a load of 1.80 MPa in accordance with ISO 75-1 and 75-2. For measuring the load deflection temperature, we used the "AUTO HDT Tester 6A-2V" manufactured by Toyo Seiki Co., Ltd.

[0136] [Table 2] [Table 3]

[0137] In Tables 2 and 3, the carbon nanotube amount in (b-1) represents the amount of carbon nanotube itself, not the amount added to the masterbatch. Molded articles formed from the resin composition of the present invention exhibited high absorption, excellent flame retardancy, and heat resistance. Furthermore, they possessed high mechanical strength. In addition, molded articles formed from the resin composition of the present invention exhibited low transmittance and reflectance. In contrast, molded articles formed from the comparative resin compositions exhibited low electromagnetic wave absorption rates and poor flame retardancy and / or heat resistance. In particular, while Comparative Example 5 had the same blending ratio (mass%) of CNTs and flame retardant in 100% by mass of the resin composition as Example 3, significant differences were observed not only in mechanical strength but also in flame retardancy and heat resistance. Specifically, the UL-94 rating for Example 3 was V-0, while for Comparative Example 5 it was V-2. [Industrial applicability]

[0138] In millimeter-wave radar, both transmitted and reflected electromagnetic waves contribute to noise and can cause malfunctions. Therefore, there is a growing demand for materials with high electromagnetic wave absorption and low transmittance and reflectivity. The resin composition of the present invention can meet these demands. Furthermore, it can also meet the requirements for high flame retardancy and heat resistance. Therefore, it is expected to be widely used in applications requiring flame retardancy, heat resistance, and electromagnetic wave absorption properties.

Claims

1. The material contains a thermoplastic resin, reinforcing fibers, carbon nanotubes, and a flame retardant, and when molded to a thickness of 2 mm, the absorption rate at a frequency of 76.5 GHz, as determined by formula (A), is 40.0 to 100%. The reinforcing fiber content is 10 to 100 parts by mass per 100 parts by mass of thermoplastic resin. The carbon nanotube content is 0.1 to 10.0 parts by mass per 100 parts by mass of thermoplastic resin. The amount of the flame retardant is 1.0 to 30.0 parts by mass per 100 parts by mass of thermoplastic resin. When the flame retardant includes a halogenated flame retardant, the flame retardant auxiliary is included in an amount of 0.1 to 20.0 parts by mass per 100 parts by mass of the thermoplastic resin. A resin composition, The resin composition is molded into a test piece with a thickness of 0.8 mm, and the flame retardancy is determined to be V-0 or V-1 according to the UL94 combustion test. A resin composition wherein the thermoplastic resin comprises at least one of polyester resin, polyamide resin, polycarbonate resin, and polyphenylene ether resin. 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.)

2. The resin composition according to claim 1, wherein the thermoplastic resin comprises a polyester resin.

3. The resin composition according to claim 1 or 2, wherein the flame retardant comprises a brominated flame retardant.

4. The resin composition according to any one of claims 1 to 3, wherein the reinforcing fibers include glass fibers.

5. The resin composition according to any one of claims 1 to 4, wherein the thermoplastic resin comprises a polybutylene terephthalate resin.

6. The resin composition according to any one of claims 1 to 5, comprising 0.1 to 10.0 parts by mass of the carbon nanotube per 100 parts by mass of the thermoplastic resin.

7. The resin composition according to any one of claims 1 to 6, wherein the carbon nanotube includes a multi-walled carbon nanotube.

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

9. An electromagnetic wave absorber formed from the resin composition according to any one of claims 1 to 7.

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