Resin composition, molded article, electromagnetic wave absorber, and method for producing resin composition

Abstract

To provide a resin composition having a high absorptivity of electromagnetic waves, a molded article, an electromagnetic wave absorber, and a method for producing the resin composition.SOLUTION: The resin composition includes a thermoplastic resin (A), a thermoplastic resin (B) and carbon nanotubes, wherein at least a part of the thermoplastic resin (B) is derived from a master batch of the carbon nanotubes, and the SP value of the thermoplastic resin (A) ≥ the SP value of the thermoplastic resin (B) is satisfied (wherein the SP value is a solubility parameter).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a molded article, an electromagnetic wave absorber, and a method for producing a resin composition. [Background technology]

[0002] Millimeter-wave radar emits millimeter-wave radio waves with wavelengths of 1 to 10 mm at frequencies between 30 and 300 GHz, particularly between 60 and 90 GHz, and detects the presence of obstacles as well as the distance and relative speed to the object by receiving the reflected waves that collide with the object. Millimeter-wave radar is being considered for use in a wide range of fields, including automobile collision prevention sensors, autonomous driving systems, road information systems, security systems, and medical and nursing care devices. Known resin compositions for such millimeter-wave radars are described in Patent Document 1. Patent Document 2 discloses a multifunctional resin composition that can be used for shielding electromagnetic interference or radio frequency interference. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-197048 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-155993 Summary of the Invention [Problem to be solved by the invention]

[0004] In millimeter-wave radar, the electromagnetic waves that pass through it are the biggest cause of malfunction, so there is a demand for resin compositions that have a high absorption rate of electromagnetic waves. The present invention aims to solve such problems and to provide a resin composition, a molded article, an electromagnetic wave absorber, and a method for producing a resin composition, which have a high absorption rate of electromagnetic waves. [Means for solving the problem]

[0005] In light of the above-mentioned problems, the present inventors have conducted research and found that when blending carbon nanotubes into a thermoplastic resin, the electromagnetic wave absorption rate of the resulting resin composition can be improved by using a masterbatch of carbon nanotubes with a thermoplastic resin having a higher SP value than the thermoplastic resin. Specifically, the above problems were solved by the following means. <1> A resin composition comprising a thermoplastic resin (A), a thermoplastic resin (B), and carbon nanotubes, wherein at least a portion of the thermoplastic resin (B) is derived from a masterbatch of the carbon nanotubes, and the SP value of the thermoplastic resin (A) is greater than or equal to the SP value of the thermoplastic resin (B) (where the SP value is a solubility parameter). <2> The concentration of carbon nanotubes in the masterbatch is 1 to 50 mass%. <1> The resin composition according to claim 1. <3> The thermoplastic resin (A) is selected from polyester resins, polycarbonate resins, and polyamide resins. <1> or <2> The resin composition according to claim 1. <4> The thermoplastic resin (B) is selected from polyester resins, polystyrene resins, and polyolefin resins. <1> ~ <3> The resin composition according to any one of the above. <5> the difference between the SP value of the thermoplastic resin (A) and the SP value of the thermoplastic resin (B) is 0 to 8.0; <1> ~ <4> The resin composition according to any one of the above. <6> the difference between the SP value of the thermoplastic resin (A) and the SP value of the thermoplastic resin (B) is 0.1 to 8.0; <1> ~ <4> The resin composition according to any one of the above. <7> The content of carbon nanotubes in the resin composition is 0.01 to 10% by mass. <1> ~ <6> The resin composition according to any one of the above. <8> When the resin composition is molded into a thickness of 2 mm, the absorption rate calculated according to formula (A) at a frequency of 76.5 GHz is 50.0 to 100%. <1> ~ <7> The resin composition according to any one of the above. Formula (A)

number

number

number

[0006] According to the present invention, it is possible to provide a resin composition, a molded article, an electromagnetic wave absorber, and a method for producing a resin composition, which have a high absorption rate of electromagnetic waves. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to only this embodiment. In this specification, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit. In this specification, various physical properties and characteristic values ​​are those at 23°C unless otherwise specified. In this specification, the weight average molecular weight and number average molecular weight are values ​​measured by GPC (gel permeation chromatography) in terms of polystyrene. In this specification, the unit of return loss and transmission loss is "dB" (decibels). If the standards shown in this specification differ depending on the year and the measurement method, etc., they will be based on the standards as of January 1, 2021, unless otherwise stated.

[0008] The resin composition of this embodiment comprises a thermoplastic resin (A), a thermoplastic resin (B), and carbon nanotubes, and is characterized in that at least a portion of the thermoplastic resin (B) is derived from a masterbatch of the carbon nanotubes, and satisfies the SP value of the thermoplastic resin (A) ≧ the SP value of the thermoplastic resin (B) (here, the SP value is a solubility parameter). By adopting such a configuration, it becomes possible to provide a resin composition with a high electromagnetic wave absorption rate. The reason is presumably as follows. That is, a resin with a high SP value has relatively many polar groups. On the other hand, when carbon nanotubes are melt-kneaded together with two or more kinds of resins, they tend to be attracted to the resin having polar groups. Therefore, when the SP value of the resin for masterbatch of carbon nanotubes is larger than the SP value of the main thermoplastic resin, it is presumed that even if the carbon nanotube masterbatch and the main thermoplastic resin are melt-kneaded, the carbon nanotubes are difficult to be dispersed in the main thermoplastic resin. In the present embodiment, by setting the SP value of the thermoplastic resin (B) for masterbatch of carbon nanotubes to be not more than the SP value of the thermoplastic resin (A), it is presumed that during melt-kneading, the carbon nanotubes can be easily dispersed in the thermoplastic resin (A) by correlatively moving from the thermoplastic resin (B) to the thermoplastic resin (A). In particular, it is presumed that by setting the difference between the SP value of the thermoplastic resin (A) and the SP value of the thermoplastic resin (B) to be 0.1 or more, the dispersion of the carbon nanotubes in the thermoplastic resin (A) can be more remarkably improved. And by improving the dispersibility of the carbon nanotubes in the thermoplastic resin (A), a high electromagnetic wave absorption rate can be achieved. Hereinafter, the resin composition of the present embodiment will be described.

[0009] <SP value> In the resin composition of the present embodiment, the SP value of the thermoplastic resin (A) ≥ the SP value of the thermoplastic resin (B) is satisfied (where the SP value is the solubility parameter). By adopting such a configuration, the dispersibility of the carbon nanotubes in the thermoplastic resin (A) tends to be improved. The difference between the SP value of thermoplastic resin (A) and the SP value of thermoplastic resin (B) is 0 or more, preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.5 or more, still more preferably 0.7 or more, and even more preferably 1.0 or more. Furthermore, the difference between the SP value of thermoplastic resin (A) and the SP value of thermoplastic resin (B) is preferably 8.0 or less, more preferably 7.0 or less, even more preferably 6.0 or less, still more preferably 5.0 or less, and even more preferably 4.0 or less. By keeping the difference below the upper limit, compatibility during melt-kneading tends to be improved. The resin composition of the present embodiment may contain only one type of thermoplastic resin (A) and one type of thermoplastic resin (B), or may contain two or more types. When two or more types are contained, it is preferable that the SP value of the mixture satisfies the above range. In this embodiment, the solubility in a solvent having a known SP value is determined, and based on this, calculation can be performed using Hansen Solubility Parameters in Practice ver. 5.0.

[0010] <Thermoplastic resin (A)> The thermoplastic resin (A) in this embodiment is usually the main resin component contained in the resin composition. Preferred examples of the thermoplastic resin used in this embodiment include polyester resin (thermoplastic polyester resin); polyamide resin; polycarbonate resin; polystyrene-based resin; polyolefin resin 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 the like. It is more preferable that the resin is selected from polyester resin, polycarbonate resin, and polyamide resin, and it is even more preferable that the resin contains polyester resin, and it is even more preferable that the resin contains polybutylene terephthalate resin.

[0011] The content of the thermoplastic resin (A) 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. When the resin composition does not contain a reinforcing material, the content of the thermoplastic resin (A) in the resin composition is preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. By setting the content to be equal to or greater than the above lower limit, fluidity during injection molding tends to be further improved. Furthermore, the content of the thermoplastic resin is preferably 99% by mass or less. When the resin composition contains a reinforcing material, the content of the thermoplastic resin (A) in the resin composition is more preferably 90% by mass or less, even more preferably 80% by mass or less, and even more preferably 75% by mass or less. By setting the content to be equal to or less than the above upper limit, the mechanical strength of the resulting molded product tends to be further improved.

[0012] <Thermoplastic resin (B)> The resin composition of this embodiment contains a thermoplastic resin (B). At least a portion of the thermoplastic resin (B) is derived from the masterbatch of carbon nanotubes. This configuration facilitates the migration of carbon nanotubes from the thermoplastic resin (B) to the thermoplastic resin (A) during melt-kneading, improving the dispersibility of the carbon nanotubes in the resin composition. Furthermore, a part of the thermoplastic resin (B) may not be derived from the masterbatch of carbon nanotubes.

[0013] The thermoplastic resin (B) is set in relation to the thermoplastic resin (A). That is, the type of thermoplastic resin (B) is not limited and can be selected appropriately as long as the relationship between the SP value of the thermoplastic resin (A) and the SP value of the thermoplastic resin (B) described above is satisfied. Preferred examples of the thermoplastic resin (B) used in this embodiment include polyester resins (thermoplastic polyester resins); polyamide resins; polycarbonate resins; polystyrene-based resins; polyolefin resins such as polyethylene resins, polypropylene resins, and cyclic cycloolefin resins; polyacetal resins; polyimide resins; polyetherimide resins; polyurethane resins; polyphenylene ether resins; polyphenylene sulfide resins; polysulfone resins; polymethacrylate resins; and the like. It is more preferred that the resin is selected from polyester resins, polystyrene-based resins, and polyolefin resins, and even more preferred that the resin is selected from polyester resins and polystyrene-based resins. It is even more preferred that the resin contains a polystyrene-based resin, and even more preferred that the resin contains HIPS (preferably butadiene rubber-containing polystyrene).

[0014] The content of thermoplastic resin (B) in the resin composition of this embodiment is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and even more preferably 2.5 parts by mass or more, per 100 parts by mass of thermoplastic resin (A). By ensuring that the content is above the lower limit, electromagnetic wave absorption performance tends to be further improved. Furthermore, the content of thermoplastic resin (B) is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 50 parts by mass or less, even more preferably 30 parts by mass or less, even more preferably 10.0 parts by mass or less, and even more preferably 8.0 parts by mass or less, 7.0 parts by mass or less, or 6.0 parts by mass or less, per 100 parts by mass of thermoplastic resin (A). By ensuring that the content is below the upper limit, the transmittance and reflectance of the resulting molded article tend to be lower.

[0015] In this embodiment, at least a part of the thermoplastic resin (B) is blended as a resin for forming a masterbatch. The concentration of the thermoplastic resin (B) in the masterbatch is preferably 99% by mass or less, more preferably 95% by mass or less, and is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more. By adjusting the concentration within the above range of not more than the upper limit and not less than the lower limit, the dispersibility of the carbon nanotubes in the thermoplastic resin (A) tends to be further improved.

[0016] In this embodiment, one example of a preferred blend form of thermoplastic resins is that the thermoplastic resin (A) contains a polyester resin (preferably a polybutylene terephthalate resin), and the thermoplastic resin (B) contains a polystyrene-based resin. In this embodiment, preferably 90 mass % or more, more preferably 95 mass % or more, and even more preferably 99 mass % or more of the resin components contained in the resin composition are composed of a polyester resin (preferably a polybutylene terephthalate resin) and a polystyrene-based resin (preferably a HIPS). Another preferred example of the thermoplastic resin in this embodiment is that the thermoplastic resin (A) contains a polyester resin (preferably, polybutylene terephthalate resin), and the thermoplastic resin (B) contains a polyester resin (preferably, polybutylene terephthalate resin). In this embodiment, 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 consists of a polyester resin (preferably, polybutylene terephthalate resin).

[0017] Each thermoplastic resin will be described in detail below.

[0018] <<Polyester resin>> As the polyester resin, known thermoplastic polyester resins can be used, and polyethylene terephthalate resin and polybutylene terephthalate resin are preferred, and it is more preferred that the polyester resin contains 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 not only polybutylene terephthalate resin (homopolymer), but also polybutylene terephthalate copolymers containing other copolymerization components other than terephthalic acid units and 1,4-butanediol units, and mixtures of homopolymers and polybutylene terephthalate copolymers.

[0019] The polybutylene terephthalate resin may contain one or more dicarboxylic acid units other than terephthalic acid. Specific examples of other 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 the polybutylene terephthalate resin used in this embodiment, terephthalic acid units preferably account for 80 mol % or more, and more preferably 90 mol % or more, of all dicarboxylic acid units.

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

[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, the polybutylene terephthalate copolymer may contain, as the carboxylic acid unit, one or more dicarboxylic acids other than the above-mentioned terephthalic acid and / or, as the diol unit, one or more diols other than the above-mentioned 1,4-butanediol. 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, polyester ether resins copolymerized with polytetramethylene glycol are preferred. These copolymers refer to those in which the copolymerization amount is 1 mol% or more and less than 50 mol% of all 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%. By setting the copolymerization amount in this range, fluidity, toughness, and tracking resistance tend to be easily improved, which is preferable.

[0022] The amount of terminal carboxyl groups in the polybutylene terephthalate resin may be appropriately selected and determined, but is typically 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 30 eq / ton or less. By setting the amount below the upper limit, alkali resistance and hydrolysis resistance tend to be improved. The lower limit of the amount of terminal carboxyl groups is not particularly specified, but is typically 10 eq / ton or more, taking into account the productivity of polybutylene terephthalate resin production.

[0023] The amount of terminal carboxyl groups in the polybutylene terephthalate resin is determined by dissolving 0.5 g of the polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating the solution with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. The amount of terminal carboxyl groups can be adjusted by any conventional method, such as adjusting the polymerization conditions, such as the raw material charge ratio, polymerization temperature, and pressure reduction, or by reacting a terminal blocking 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. By making the intrinsic viscosity 0.5 dL / g or more, the mechanical strength of the resulting resin composition tends to be further improved. Furthermore, by making the intrinsic viscosity 2 dL / g or less, the fluidity of the resin composition tends to be further improved, and moldability tends to be improved. The intrinsic viscosity of the polybutylene terephthalate resin is a value measured at 30° C. in a mixed solvent of tetrachloroethane and phenol in a 1:1 (mass ratio).

[0025] Polybutylene terephthalate resin can be produced by batch or continuous melt polymerization of a dicarboxylic acid component containing terephthalic acid as the main component or an ester derivative thereof with a diol component containing 1,4-butanediol as the main component. 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-state polymerization under a nitrogen gas flow or reduced pressure. The polybutylene terephthalate resin is preferably one obtained by a production method in which a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of 1,4-butanediol are subjected to continuous melt polycondensation.

[0026] The catalyst used in carrying out the esterification reaction may be a conventionally known catalyst, such as a titanium compound, a tin compound, a magnesium compound, or a calcium compound. Among these, titanium compounds are particularly preferred. Specific examples of titanium compounds used 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 polyester resin may be found in paragraphs 0013 to 0016 of JP-A-2010-174223, the contents of which are incorporated herein by reference.

[0028] <<Polycarbonate resin>> Polycarbonate resins are homopolymers or copolymers, which may be branched, obtained by reacting a dihydroxy compound or a small amount of a polyhydroxy compound with phosgene or a carbonate diester. The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by the conventionally known phosgene method (interfacial polymerization method) or melt method (ester interchange method) can be used.

[0029] The dihydroxy compound used as the raw material is preferably an aromatic dihydroxy compound, such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, or 4,4-dihydroxydiphenyl, with bisphenol A being preferred. It is also possible to use a compound in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compound.

[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. Also, copolymers mainly composed of aromatic polycarbonate resins, such as copolymers with polymers or oligomers having a siloxane structure, may be used. Furthermore, two or more of the above-mentioned polycarbonate resins may be mixed and used.

[0031] To adjust the molecular weight of the polycarbonate resin, a monovalent aromatic hydroxy compound may be used, such as m- and p-methylphenol, m- and p-propylphenol, p-tert-butylphenol, and p-long-chain alkyl-substituted phenol.

[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. By using a polycarbonate resin having a viscosity average molecular weight of 5,000 or more, the mechanical strength of the resulting resin composition tends to be further improved. 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. By using a polycarbonate resin having a viscosity average molecular weight of 60,000 or less, the flowability of the resin composition tends to be improved, and moldability tends to be improved. When two or more types of polycarbonate resins are contained, it is preferable that the mixture satisfies the above range (hereinafter, the same applies to molecular weight).

[0033] In this embodiment, the viscosity average molecular weight (Mv) of the polycarbonate resin is a value calculated from the intrinsic viscosity ([η]) obtained by measuring the viscosity of a methylene chloride solution of the polycarbonate resin at 20°C using an Ubbelohde viscometer, and then using the following Schnell viscosity formula: [η]=1.23×10 -4 Mv 0.83

[0034] The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by either the phosgene method (interfacial polymerization method) or the melt method (ester interchange method) can be used. Also preferred is a polycarbonate resin produced by the melt method and then subjected to post-treatment to adjust the amount of terminal OH groups.

[0035] <<Polyamide resin>> The polyamide resin is a polymer having, as a constituent unit, an acid amide obtained by ring-opening polymerization of lactam, polycondensation of aminocarboxylic acid, or polycondensation of diamine and dibasic acid, and may be either an aliphatic polyamide resin or a semi-aromatic polyamide resin. Specific examples include polyamide 6, 11, 12, 46, 66, 610, 612, 6I, 6 / 66, 6T / 6I, 6 / 6T, 66 / 6T, 66 / 6T / 6I, 9T, 10T, xylylenediamine-based polyamide resins (details of which will be described later), polytrimethylhexamethylene terephthalamide, polybis(4-aminocyclohexyl)methanedodecamide, polybis(3-methyl-4-aminocyclohexyl)methanedodecamide, and polyundecamethylene hexahydroterephthalamide. The "I" in the above text represents an isophthalic acid component, and the "T" represents a terephthalic acid component. Regarding polyamide resins, the description in paragraphs 0011 to 0013 of JP 2011-132550 A can be found, the contents of which are incorporated herein by reference.

[0036] The polyamide resin used in this embodiment is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, and is preferably a xylylenediamine-based polyamide resin in which 50 mol% or more of the diamine-derived structural units are derived from xylylenediamine. The diamine-derived structural units of the xylylenediamine-based polyamide resin are preferably derived from at least one of meta-xylylenediamine and para-xylylenediamine by 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more. The dicarboxylic acid-derived structural units of the xylylenediamine-based polyamide resin are preferably derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms by 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more. Suitable α,ω-straight chain aliphatic dibasic acids having 4 to 20 carbon atoms include adipic acid, sebacic acid, suberic acid, dodecanedioic acid, and eicodionic acid, with adipic acid and sebacic acid being more preferred.

[0037] Diamines other than metaxylylenediamine and paraxylylenediamine that can be used as raw 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-trimethylhexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine; 1,3-bis( Examples of the diamine include alicyclic diamines such as bis(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; and diamines having an aromatic ring such as bis(4-aminophenyl)ether, paraphenylenediamine, and bis(aminomethyl)naphthalene. These diamines can be used alone or in combination of two or more.

[0038] Examples of dicarboxylic acid components other than the above-mentioned α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms include phthalic acid 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, and these can be used alone or in combination of two or more.

[0039] <<Polystyrene resin>> Examples of polystyrene-based resins include homopolymers of styrene-based monomers and copolymers of styrene-based monomers and monomers copolymerizable with styrene-based monomers. Examples of styrene-based monomers include styrene, α-methylstyrene, chlorostyrene, methylstyrene, and tert-butylstyrene. In the styrene-based resin of this embodiment, 50 mol % or more of the monomer units are styrene-based monomers. More specific examples of 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), and styrene-IPN type rubber copolymer. In this embodiment, the styrene resin is preferably an 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), or styrene-IPN type rubber copolymer, more preferably a high impact polystyrene resin (HIPS), and even more preferably a butadiene rubber-containing polystyrene.

[0040] When the polystyrene resin contains a rubber component, the content of the rubber component in the polystyrene resin is preferably 3 to 70% by mass, more preferably 5 to 50% by mass, and even more preferably 7 to 30% by mass. A rubber component content of 3% by mass or more tends to improve impact resistance, and a rubber component content of 50% by mass or less is preferred because it tends to improve flame retardancy. The average particle size of the rubber component is preferably 0.05 to 10 μm, more preferably 0.1 to 6 μm, and even more preferably 0.2 to 3 μm. An average particle size of 0.05 μm or more tends to improve impact resistance, and an average particle size of 10 μm or less tends to improve appearance, which is preferred.

[0041] The weight-average molecular weight of the polystyrene resin is usually 50,000 or more, preferably 100,000 or more, more preferably 150,000 or more, and usually 500,000 or less, preferably 400,000 or less, more preferably 300,000 or less. The number-average molecular weight is usually 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and preferably 500,000 or less, more preferably 300,000 or less.

[0042] The melt flow rate (MFR) of the polystyrene resin, measured in accordance with JIS K7210 (temperature 200°C, load 5 kgf), is preferably 0.1 to 30 g / 10 min, more preferably 0.5 to 25 g / 10 min. An MFR of 0.1 g / 10 min or more tends to improve fluidity, while an MFR of 30 g / 10 min or less tends to improve impact resistance.

[0043] Examples of methods for producing such polystyrene resins include known methods such as emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization.

[0044] <Carbon nanotubes> The resin composition of the present embodiment contains carbon nanotubes, which can impart electromagnetic wave absorbing properties to the resin composition.

[0045] In the resin composition of this embodiment, the carbon nanotubes are blended in the form of a masterbatch with the thermoplastic resin (B). By blending the carbon nanotubes in the form of a masterbatch with the thermoplastic resin (B), the dispersibility of the carbon nanotubes in the thermoplastic resin (A) can be effectively improved. The concentration of carbon nanotubes in the masterbatch is preferably 1% by mass or more, preferably 5% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 20% by mass or less. By adjusting the concentration within the range of the above upper limit or less and the above lower limit or more, the dispersibility of carbon nanotubes in the thermoplastic resin (A) tends to be further improved.

[0046] The carbon nanotubes used in this embodiment are single-walled carbon nanotubes and / or multi-walled carbon nanotubes, and preferably contain at least multi-walled carbon nanotubes. Carbon materials partially having a carbon nanotube structure can also be used. The carbon nanotubes are not limited to a cylindrical shape, and may have a coiled shape with a spiral at a pitch of 1 μm or less. Carbon nanotubes are commercially available, and examples thereof include carbon nanotubes available from Bayer MaterialScience, Nanosil, Showa Denko K.K., and Hyperion Catalysis International, Inc. In addition to the name carbon nanotubes, they are also called graphite fibrils, carbon fibrils, etc. The diameter (number average fiber diameter) of the carbon nanotubes is preferably 0.5 to 100 nm, more preferably 1 to 30 nm. From the viewpoint of imparting good electromagnetic wave absorption properties, the aspect ratio of the carbon nanotubes is preferably 5 or more, more preferably 50 or more. There is no particular upper limit, but it is, for example, 500 or less.

[0047] The content of carbon nanotubes in the resin composition of this embodiment is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and may be 0.2% by mass or more, or even 0.4% by mass or more. By making the content equal to or greater than the lower limit, electromagnetic wave absorption properties are effectively exhibited. Furthermore, the content of carbon nanotubes in the resin composition of this embodiment is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, even more preferably 3% by mass or less, may be 2% by mass or less, or even 1% by mass or less. By making the content equal to or less than the upper limit, the fluidity of the resin tends to be further improved.

[0048] The resin composition of this embodiment preferably contains 0.1 parts by mass or more of carbon nanotubes per 100 parts by mass of the thermoplastic resin (A). By setting the content at or above the lower limit, electromagnetic wave absorption properties are effectively exhibited. The resin composition of this embodiment preferably contains 10.0 parts by mass or less of carbon nanotubes per 100 parts by mass of the thermoplastic resin (A), 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 even 2.5 parts by mass or less, particularly 1.5 parts by mass or less. Setting the content at or below the upper limit tends to further improve the fluidity of the resin. The resin composition of the present embodiment may contain only one type of carbon nanotube, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0049] <Other ingredients> The resin composition of this embodiment may contain other components in addition to those described above, as necessary, as long as the desired physical properties are not significantly impaired. Examples of other components include reinforcing materials and various resin additives. Note that the other components may be contained alone or in any combination and ratio of two or more.

[0050] Examples of various resin additives include stabilizers, mold release agents, flame retardants, reactive compounds, pigments, dyes, UV absorbers, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, dispersants, antibacterial agents, etc. The resin composition of the present embodiment preferably contains at least one of stabilizers and mold release agents. The resin composition of this embodiment is prepared so that the total of the thermoplastic resin (A), thermoplastic resin (B), carbon nanotubes, and other optional components is 100% by mass. It is also preferable that the total of the thermoplastic resin (A), thermoplastic resin (B), carbon nanotubes, stabilizer, and release agent in the resin composition of this embodiment account for 99% or more by mass of the resin composition. It is also preferable that the total of the thermoplastic resin (A), thermoplastic resin (B), carbon nanotubes, reinforcing material (preferably glass fiber), stabilizer, and release agent in the resin composition of this embodiment account for 99% or more by mass of the resin composition.

[0051] <<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 preferred to use a hindered phenol compound and a phosphorus compound in combination. As the stabilizer, specifically, the descriptions in paragraphs 0046 to 0057 of JP 2018-070722 A, the descriptions in paragraphs 0030 to 0037 of JP 2019-056035 A, and the descriptions in paragraphs 0066 to 0078 of WO 2017 / 038949 A can be referred to, the contents of which are incorporated herein by reference.

[0052] The resin composition of this embodiment preferably contains 0.01 parts by mass or more of the stabilizer per 100 parts by mass of the thermoplastic resin (A), more preferably 0.05 parts by mass or more, and even more preferably 0.08 parts by mass or more. The upper limit of the amount of the stabilizer is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less per 100 parts by mass of the thermoplastic resin (A). The resin composition of the present embodiment may contain only one stabilizer, or may contain two or more stabilizers. When two or more stabilizers are contained, the total amount is preferably in the above range.

[0053] <<Release Agent>> The resin composition of the present embodiment preferably contains a release agent. As the release agent, a wide variety of known release agents can be used, and preferred are esters of aliphatic carboxylic acids, paraffin wax, polystyrene wax, and polyolefin wax, with polyethylene wax being more preferred. For details of the release agent, please refer to the descriptions in paragraphs 0115 to 0120 of JP-A No. 2013-007058, paragraphs 0063 to 0077 of JP-A No. 2018-070722, and paragraphs 0090 to 0098 of JP-A No. 2019-123809, the contents of which are incorporated herein by reference.

[0054] The resin composition of this embodiment preferably contains 0.01 parts by mass or more of the release agent relative to 100 parts by mass of the thermoplastic resin (A), more preferably 0.08 parts by mass or more, and even more preferably 0.2 parts by mass or more. The upper limit of the amount of the release agent contained is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and even more preferably 0.8 parts by mass or less relative to 100 parts by mass of the thermoplastic resin (A). The resin composition may contain only one type of release agent, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0055] <<Reinforcement material>> The resin composition of the present embodiment may or may not contain a reinforcing material. By containing a reinforcing material, the mechanical strength of the resulting molded article can be improved. The reinforcing material that can be used in this embodiment is not particularly limited in terms of type, and may be any of fibers, fillers, beads, etc., with fibers being preferred.

[0056] When the reinforcing material is a fiber, it may be a short fiber or a long fiber. When the reinforcing material is short fibers, fillers, beads, or the like, the resin composition of this embodiment may be in the form of pellets, powdered pellets, or a film formed from the pellets. When the reinforcing material is a long fiber, examples of the reinforcing material include so-called long fiber for unidirectional (UD) materials, sheet-like long fiber such as woven fabric and knitted fabric, etc. When using these long fibers, the components other than the reinforcing material of the resin composition of the present embodiment can be impregnated into the sheet-like long fiber reinforcing material to form a sheet-like resin composition (for example, a prepreg).

[0057] The raw materials for the reinforcing material 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, bamboo, etc.), aramid, polyoxymethylene, aromatic polyamide, polyparaphenylene benzobisoxazole, and ultra-high molecular weight polyethylene, with glass being preferred.

[0058] The resin composition of the present embodiment preferably contains glass fibers as a reinforcing material. The glass fiber is 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 fiber refers to a fibrous material whose cross section, cut perpendicular to the longitudinal direction, is circular or polygonal. The number-average fiber diameter of the single fiber of the glass fiber is usually 1 to 25 μm, preferably 5 to 17 μm. By making the number-average fiber diameter 1 μm or more, the molding processability of the resin composition tends to be further improved. By making the number-average fiber diameter 25 μm or less, the appearance of the obtained molded article tends to be improved, and the reinforcing effect also tends to be improved. The glass fiber may be a single fiber or a plurality of single fibers twisted together. The glass fiber may be in the form of a glass roving obtained by continuously winding a single fiber or a plurality of twisted fibers, a chopped strand cut to a length of 1 to 10 mm (i.e., glass fiber having a number average fiber length of 1 to 10 mm), or a milled fiber pulverized to a length of about 10 to 500 μm (i.e., glass fiber having a number average fiber length of 10 to 500 μm), but chopped strand cut to a length of 1 to 10 mm is preferred. Glass fibers of different forms can also be used in combination. Glass fibers having an irregular cross-sectional shape are also preferred. The irregular cross-sectional shape has an oblateness, which is the ratio of the major axis to the minor axis of the cross section perpendicular to the longitudinal direction of the fiber, of, for example, 1.5 to 10, preferably 2.5 to 10, more preferably 2.5 to 8, and even more preferably 2.5 to 5.

[0059] The glass fiber may be surface-treated with, for example, a silane-based compound, an epoxy-based compound, a urethane-based compound, or the like, or may be oxidized, in order to improve its affinity with the resin component, as long as the properties of the resin composition of this embodiment are not significantly impaired.

[0060] When the resin composition of this embodiment contains a reinforcing material (preferably glass fiber), the content thereof 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, and even more preferably 40 parts by mass or more, relative to 100 parts by mass of the thermoplastic resin (A). By setting the content at or above the lower limit, the mechanical strength of the obtained molded article tends to be further increased. Furthermore, the content of the reinforcing material (preferably glass fiber) is preferably 100 parts by mass or less, 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, relative to 100 parts by mass of the thermoplastic resin (A). By setting the content at or below the upper limit, the appearance of the molded article tends to be improved, and the flowability of the resin composition tends to be further improved.

[0061] When the resin composition of this embodiment contains a reinforcing material (preferably glass fiber), the content thereof in the resin composition 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. The content of the reinforcing material (preferably glass fiber) in the resin composition 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. By setting the content at or above the lower limit, mechanical strength tends to be further increased. By setting the content at or below the upper limit, the appearance of the molded article tends to be improved, and the fluidity of the resin composition when melted tends to be further improved. The resin composition of the present embodiment may contain only one type of reinforcing material (preferably glass fiber), or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0062] <Physical properties of resin composition> The resin composition of this embodiment preferably has a high absorption rate of electromagnetic waves. Specifically, the resin composition of this embodiment preferably has an absorption rate of 50.0 to 100% at a frequency of 76.5 GHz calculated according to formula (A) when molded into a 2 mm thickness (preferably, 100 mm × 100 mm × 2 mm thickness). Formula (A)

number

[0063] The absorbency is preferably 53.0% or more, more preferably 55.0% or more, even more preferably 58.0% or more, even more preferably 60.0% or more, and even more preferably 64.0% or more. The upper limit is ideally 100%, but even if it is 90.0% or less, the required performance is sufficiently met.

[0064] The resin composition of this embodiment preferably has low reflectance of electromagnetic waves. Specifically, the resin composition of this embodiment preferably has a reflectance of 40.0% or less at a frequency of 76.5 GHz, as calculated according to formula (B), when molded to a thickness of 2 mm (preferably, 100 mm x 100 mm x 2 mm). Formula (B)

number

[0065] The reflectance is preferably 35.0% or less, more preferably 30.0% or less, even more preferably 26.0% or less, even more preferably 22.0% or less, and even more preferably 18.5% or less. The lower limit is ideally 0%, but even if it is 5.0% or more, or even 10.0% or more, the required performance is sufficiently met.

[0066] The resin composition of the present embodiment preferably has low transmittance. The resin composition of this embodiment preferably has a transmittance of 25.0% or less at a frequency of 76.5 GHz as determined according to formula (C) when molded into a 2 mm thick piece (preferably 100 mm x 100 mm x 2 mm thick piece). Formula (C)

number

[0067] The transmittance is preferably 23.0% or less, and more preferably 20.0% or less. The lower limit is ideally 0%, but even if it is 5.0% or more, the required performance is sufficiently met.

[0068] The resin composition of the present embodiment preferably satisfies all of the absorptance calculated according to the above formula (A), the reflectance calculated according to the above formula (B), and the transmittance calculated according to the above formula (C).

[0069] The resin composition of this embodiment preferably has a high relative dielectric constant and a high dielectric loss tangent. The resin composition of this embodiment preferably has a relative dielectric constant at a frequency of 76.5 GHz of 4.50 or more, more preferably 4.60 or more, even more preferably 4.75 or more, even more preferably 4.90 or more, even more preferably 5.00 or more, and even more preferably 5.10 or more. By setting the relative dielectric constant at or above the lower limit, the electromagnetic wave absorption rate of the resulting molded article tends to be higher. Furthermore, the upper limit of the relative dielectric constant is preferably 8.00 or less, more preferably 6.00 or less, even more preferably 5.50 or less, even more preferably 5.30 or less, and even more preferably 5.20 or less. By setting the relative dielectric constant at or below the upper limit, the electromagnetic wave reflectivity of the resulting molded article tends to be lower. The resin composition of this embodiment preferably has a dielectric loss tangent at a frequency of 76.5 GHz of 0.10 or more, more preferably 0.12 or more, even more preferably 0.14 or more, even more preferably 0.16 or more, even more preferably 0.18 or more, and even more preferably 0.21 or more. By setting the dielectric loss tangent at or above the lower limit, the electromagnetic wave absorption rate of the resulting molded article tends to be higher. Furthermore, the lower limit of the dielectric loss tangent is not particularly specified, but may be, for example, 0.50 or less, or even 0.40 or less. By setting the dielectric loss tangent at or below the upper limit, the electromagnetic wave reflectivity of the resulting molded article tends to be lower.

[0070] The resin composition of the present embodiment preferably has excellent mechanical strength. The resin composition of this embodiment preferably has particularly excellent tensile properties. For example, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (thickness 4 mm), the tensile strength at maximum point measured according to ISO 527-1 and ISO 527-2 is preferably 40 MPa or more, more preferably 50 MPa or more. There is no particular upper limit for the tensile strength at maximum point, but for example, even a value of 200 MPa or less is still practical. Furthermore, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (thickness 4 mm), the tensile modulus measured in accordance with ISO 527-1 and ISO 527-2 is preferably 1500 MPa or more, more preferably 1800 MPa or more, and even more preferably 2000 MPa or more. There is no particular upper limit to the tensile modulus, but, for example, even a value of 12000 MPa or less is within a practical level. Furthermore, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (thickness 4 mm), the tensile strain measured according to ISO 527-1 and ISO 527-2 is preferably 1.0% or more, more preferably 2.0% or more. There is no particular upper limit for the tensile strain, but, for example, a value of 30% or less is also practical.

[0071] Furthermore, the resin composition of the present embodiment preferably has excellent bending properties. Specifically, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (thickness 4 mm), the bending strength is preferably 50 MPa or more, more preferably 70 MPa or more. The upper limit of the bending strength is not particularly specified, but for example, 300 MPa or less is practical. Furthermore, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (thickness 4 mm), the flexural modulus is preferably 1,500 MPa or more, more preferably 2,000 MPa or more. The upper limit of the flexural modulus is not particularly specified, but for example, 15,000 MPa or less is practical.

[0072] Furthermore, the resin composition of the present embodiment preferably has excellent impact resistance. Specifically, when the resin composition of this embodiment is molded into an ISO multipurpose test piece (thickness 4 mm), the notched Charpy impact strength according to the ISO179 standard is 2.0 kJ / m 2 It is preferable that the concentration is 3.0 kJ / m or more. 2The upper limit of the notched Charpy impact strength is not particularly limited, but is preferably 50 kJ / m or more. 2 The following is practical:

[0073] The resin composition of the present embodiment also has a surface resistance of 1.0×10 when molded into a test piece having a thickness of 2 mm (preferably, 100 mm×100 mm×2 mm) according to IEC 60093. 11 Ω or more is preferable, and 1.0×10 12 Ω or more is more preferable, and 1.0×10 13 It is more preferable that the resistance is 1.0×10 Ω or more. 14 Ω or more is more preferable, and 1.0×10 16 Ω or less is preferable, and 1.0×10 15 It is more preferable that the hardness is Ω or more. By setting the hardness in this range, the electromagnetic wave absorption rate of the obtained molded article tends to be higher. The resin composition of the present embodiment further has a volume resistivity of 1.0×10 in accordance with IEC 60093 on a test piece of 2 mm thickness (preferably, 100 mm×100 mm×2 mm thickness). 10 It is preferable that the resistance is Ω·cm or more, and 1.0×10 11 It is more preferable that the resistance is Ω·cm or more, and 1.0×10 12 It is more preferable that the resistance is 1.0×10 Ω·cm or more. 13 It is more preferable that the resistance is Ω·cm or less, and 1.0×10 14 It is more preferable that the resistance is Ω·cm or more, and 1.0×10 15 It is even more preferable that the resistivity is Ω·cm or more, and 1.0×10 17 It is preferable that the resistance is Ω·cm or less, and 1.0×10 16 It is more preferable that the resistivity is Ω·cm or less. By setting the resistivity in this range, the electromagnetic wave absorption rate of the obtained molded article tends to be higher. The details of the measurement method are as described in the Examples.

[0074] <Method of manufacturing resin composition> The resin composition of this embodiment can be produced by a conventional method for producing a resin composition containing a thermoplastic resin. For example, it can be obtained by melt-kneading a thermoplastic resin (A) and carbon nanotubes masterbatched with a thermoplastic resin (B). In this case, the resin composition satisfies the SP value of the thermoplastic resin (A) ≧ the SP value of the thermoplastic resin (B). More specifically, the resin composition of this embodiment is produced by feeding the thermoplastic resin (A), carbon nanotubes masterbatched with the thermoplastic resin (B), and other components that are blended as needed into an extruder, and melt-kneading the mixture. The components may be mixed in advance and fed all at once to the extruder, or the components may be mixed in advance without mixing, or only a portion of the components may be mixed in advance, and then fed to the extruder using a feeder. The extruder may be a single-screw extruder or a twin-screw extruder. When glass fibers are compounded, they are preferably fed from a side feeder midway through the cylinder of the extruder. The heating temperature during melt-kneading can usually be appropriately selected from the range of 170 to 350°C.

[0075] <Method of manufacturing molded body> A molded article, particularly an electromagnetic wave absorber, is formed from the resin composition of this embodiment. The method for producing the molded article in this embodiment is not particularly limited, and any molding method commonly used for resin compositions containing thermoplastic resins can be used. Examples include injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted hollow molding, molding using a heat-insulating mold, molding using a rapidly heated mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding), extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, etc., and among these, injection molding is preferred.

[0076] <Application> The electromagnetic wave absorber of this embodiment is formed from the resin composition of this embodiment. That is, the resin composition of this embodiment is preferably used for an electromagnetic wave absorber (also referred to as an electromagnetic wave absorbing member), more preferably for an electromagnetic wave absorber having a frequency of at least 60 to 90 GHz, and even more preferably for an electromagnetic wave absorber having a frequency of at least 70 to 80 GHz. Such an electromagnetic wave absorber is preferably used for radar applications. Specifically, it is used for housings, covers, etc. for millimeter-wave radar. The electromagnetic wave absorber of this embodiment can be suitably used for in-vehicle millimeter-wave radars used in automatic brake control devices, inter-vehicle distance control devices, pedestrian accident reduction steering devices, erroneous transmission suppression control devices, devices for suppressing acceleration when pedal misapplication occurs, devices for warning of approaching vehicles, lane keeping assist devices, rear-end collision prevention warning devices, parking assist devices, devices for warning of obstacles around the vehicle, etc.; railway and aviation millimeter-wave radars used in platform monitoring / railroad crossing obstacle detection devices, in-train content transmission devices, tram / railroad collision prevention devices, foreign object detection devices in runways, etc.; millimeter-wave radars for transportation infrastructure such as intersection monitoring devices and elevator monitoring devices; millimeter-wave radars for various security devices; millimeter-wave radars for medical and nursing care such as systems for watching over children and the elderly; millimeter-wave radars for transmitting various information content; etc. [Example]

[0077] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be appropriately changed without departing 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 the like, measurements can be made using other instruments with equivalent performance.

[0078] raw material The following raw materials were used: In Table 1 below, HIPS stands for high impact polystyrene, PBT stands for polybutylene terephthalate resin, PA stands for polyamide resin, and CNT stands for carbon nanotubes (same for Table 2).

[0079] [Table 1]

[0080] Examples 1 and 2, Comparative Example 1 <Production of Resin Composition (Pellets)> As shown in Table 2, the components listed in Table 1 were placed in a stainless steel tumbler and mixed under stirring for 1 hour. The resulting mixture was fed into an intermeshing co-rotating twin-screw extruder ("TEX-30α" manufactured by The Japan Steel Works, Ltd., screw diameter 32 mm, L / D = 42) through the main feed port. The barrel temperature of the first kneading section was set to 250°C, and the melt-kneading was carried out at a discharge rate of 40 kg / h and a screw rotation speed of 200 rpm. The mixture was then extruded as a strand using a four-hole nozzle (circular (φ4 mm), length 1.5 cm). The extruded strand was introduced into a water bath for cooling, then inserted into a pelletizer and cut to obtain a resin composition (pellets).

[0081] <76.5GHz electromagnetic wave absorption rate, reflectance, transmittance> The pellets obtained above were injection molded in an injection molding machine ("NEX80" manufactured by Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test pieces measuring 100 mm x 100 mm x 2 mm thick. Using the test pieces obtained, the absorptance calculated according to formula (A), the reflectance calculated according to formula (B), and the transmittance calculated according to formula (C) at a frequency of 76.5 GHz were measured as follows. For the measurements, a Keysight network analyzer "N5252A" was used. The measurement was performed by placing the test piece so that the TD (transverse direction) direction of the injection molded article was parallel to the direction of the electric field. Formula (A)

number

[0082] Formula (B)

number

[0083] Formula (C)

number

[0084] <Relative permittivity and dielectric loss tangent> The pellets obtained above were injection molded in an injection molding machine (NEX80 manufactured by Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test pieces measuring 100 mm x 100 mm x 2 mm thick. The dielectric constant and dielectric loss tangent at a frequency of 76.5 GHz were determined using the obtained test specimen. The test specimen was placed so that the TD (transverse direction) direction of the injection-molded article was parallel to the electric field direction. The measurements were performed using a Keysight network analyzer "N5252A," and the values ​​of the relative permittivity and dielectric loss tangent were estimated using Keysight's "N1500A Materials Measurement Suite," with each value calculated using the "NIST Precision" calculation model.

[0085] <Tensile properties> The resin pellets obtained above were dried at 120°C for 5 hours, and then ISO multipurpose test specimens (thickness 4 mm) were injection molded using an injection molding machine ("J85AD" manufactured by The Japan Steel Works, Ltd.) under conditions of a cylinder temperature of 250°C and a mold temperature of 80°C. Using the molded multipurpose ISO multipurpose test specimens, the maximum tensile strength (unit: MPa), tensile modulus (unit: MPa), and tensile strain (unit: %) were measured in accordance with ISO527-1 and ISO527-2.

[0086] <Bending properties> The resin pellets obtained above were dried at 120°C for 5 hours, and then ISO multipurpose test specimens (thickness 4 mm) were injection molded using an injection molding machine ("J85AD" manufactured by The Japan Steel Works, Ltd.) under conditions of a cylinder temperature of 250°C and a mold temperature of 80°C. The flexural strength (unit: MPa) and flexural modulus (unit: MPa) were measured using the molded multipurpose ISO multipurpose test specimens in accordance with ISO178.

[0087] <Notched Charpy impact strength> The resin pellets obtained above were dried at 120°C for 5 hours, and then ISO multipurpose test specimens (thickness 4 mm) were injection molded using an injection molding machine ("J85AD" manufactured by The Japan Steel Works, Ltd.) under conditions of a cylinder temperature of 250°C and a mold temperature of 80°C. According to ISO179 standard, the ISO multipurpose test piece obtained above was cut to a specified size and shape, and the Charpy impact strength (notched) was measured. The unit is kJ / m 2 As shown.

[0088] <Surface resistance> The pellets obtained above were injection molded in an injection molding machine (NEX80 manufactured by Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test pieces measuring 100 mm x 100 mm x 2 mm thick. The surface resistance (unit: Ω) of the obtained test piece was measured in accordance with IEC60093. For the measurements, an "R8340 ULTRA HIGH RESISTANCE METER" manufactured by ADVANTEST was used.

[0089] <Volume resistance> The pellets obtained above were injection molded in an injection molding machine (NEX80 manufactured by Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test pieces measuring 100 mm x 100 mm x 2 mm thick. Using the obtained test pieces, the volume resistivity (unit: Ω·cm) was measured in accordance with IEC60093. For the measurements, an "R8340 ULTRA HIGH RESISTANCE METER" manufactured by ADVANTEST was used.

[0090] [Table 2]

[0091] In Table 2 above, the CNT content indicates the amount of carbon nanotubes in the resin composition. As is clear from the above results, the resin composition of the present invention had a high electromagnetic wave absorption rate. Furthermore, it had low electromagnetic wave transmittance and reflectance. Furthermore, the molded article formed from the resin composition of the present invention had excellent mechanical strength.

Claims

1. A thermoplastic resin (A), a thermoplastic resin (B); and carbon nanotubes, At least a part of the thermoplastic resin (B) is derived from the carbon nanotube masterbatch, The SP value of the thermoplastic resin (A) is greater than or equal to the SP value of the thermoplastic resin (B) (where the SP value is a solubility parameter). Resin composition.

2. The resin composition according to claim 1, wherein the concentration of the carbon nanotubes in the masterbatch is 1 to 50 mass %.

3. The resin composition according to claim 1 or 2, wherein the thermoplastic resin (A) is selected from the group consisting of polyester resins, polycarbonate resins, and polyamide resins.

4. The resin composition according to any one of claims 1 to 3, wherein the thermoplastic resin (B) is selected from polyester resins, polystyrene-based resins, and polyolefin resins.

5. The resin composition according to any one of claims 1 to 4, wherein the difference between the SP value of the thermoplastic resin (A) and the SP value of the thermoplastic resin (B) is 0 to 8.

0.

6. The resin composition according to any one of claims 1 to 4, wherein the difference between the SP value of the thermoplastic resin (A) and the SP value of the thermoplastic resin (B) is 0.1 to 8.

0.

7. The resin composition according to any one of claims 1 to 6, wherein the content of carbon nanotubes in the resin composition is 0.01 to 10 mass%.

8. The resin composition according to any one of claims 1 to 7, wherein the absorption rate calculated according to formula (A) at a frequency of 76.5 GHz when the resin composition is molded to a thickness of 2 mm is 50.0 to 100%. The resin composition. Formula (A) [Equation 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.)

9. The resin composition according to any one of claims 1 to 8, wherein the reflectance calculated according to formula (B) at a frequency of 76.5 GHz when molded to a thickness of 2 mm is 40.0% or less. Formula (B) [Equation 2] (In the above formula (B), R represents the return loss measured by the free space method.)

10. The resin composition according to any one of claims 1 to 9, wherein the transmittance calculated according to formula (C) at a frequency of 76.5 GHz when molded to a thickness of 2 mm is 25.0% or less. Formula (C) [Equation 3] (In the above formula (C), T represents the transmission attenuation measured by the free space method.)

11. The resin composition according to any one of claims 1 to 10, wherein the thermoplastic resin (B) is contained in an amount of 1.0 to 100 parts by mass per 100 parts by mass of the thermoplastic resin (A).

12. The resin composition according to any one of claims 1 to 11, which is used for an electromagnetic wave absorber.

13. A molded article formed from the resin composition according to any one of claims 1 to 12.

14. An electromagnetic wave absorber formed from the resin composition according to any one of claims 1 to 12.

15. The method includes melt-kneading a thermoplastic resin (A) and carbon nanotubes masterbatched with a thermoplastic resin (B), The SP value of the thermoplastic resin (A) is greater than or equal to the SP value of the thermoplastic resin (B) (where the SP value is a solubility parameter). A method for producing a resin composition.

16. The method for producing a resin composition according to claim 15, wherein the resin composition is the resin composition according to any one of claims 1 to 12.

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