Resin composition, molded body, and electromagnetic wave absorber

Abstract

To provide a resin composition having high absorptivity of electromagnetic waves and having high chemical resistance and flame retardancy, and a molded product and an electromagnetic wave absorber.SOLUTION: A resin composition contains crystalline thermoplastic resin, carbon nanotubes, and a flame retardant. When molded into thickness of 2 mm, its absorptivity at frequency 76.5 GHz is 40.0-100% as determined by the following formula (where R is a reflection attenuation measured by the free space method and T is a transmission attenuation measured by the free space method).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 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] For millimeter-wave radar, there is an increasing demand for materials with high electromagnetic wave absorption. Furthermore, even for electromagnetic wave absorbing materials, flame retardancy and chemical resistance are required depending on the application. The present invention aims to solve these problems and to provide a resin composition that has a high electromagnetic wave absorption rate and excellent flame retardancy and chemical resistance, as well as a molded article and an electromagnetic wave absorber. [Means for solving the problem]

[0005] In light of the above-mentioned problems, the present inventors have conducted research and found that the above-mentioned problems can be solved by blending carbon nanotubes and a flame retardant into a crystalline thermoplastic resin and adjusting the absorption rate to fall within a predetermined range. Specifically, the above problems were solved by the following means. <1> A resin composition comprising a crystalline thermoplastic resin, carbon nanotubes, and a flame retardant, which, when molded to a thickness of 2 mm, has an absorptivity of 40.0 to 100% at a frequency of 76.5 GHz as determined according to formula (A). Formula (A)

number

[0006] The present invention makes it possible to provide a resin composition having a high absorption rate of electromagnetic waves and excellent flame retardancy and chemical resistance, as well as a molded article and an electromagnetic wave absorber. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a molded body set on a jig capable of applying a three-way bending load, which was used to evaluate chemical resistance in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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 term "(meth)acrylate" means at least one of methacrylate and acrylate. In this specification, unless otherwise specified, 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). In cases where the standards shown in this specification differ depending on the year and the measurement method, etc., the standards shall be based on the standards in effect at the time of filing unless otherwise stated.

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

number

[0010] Furthermore, in millimeter-wave radar, not only transmitted electromagnetic waves but also reflected electromagnetic waves become noise and cause malfunction. Therefore, there is an increasing demand for materials with high electromagnetic wave absorption rate and low transmittance and reflectance. The resin composition of the present embodiment is preferable in that a molded article with high electromagnetic wave absorption rate and low transmittance and reflectance can be obtained. In addition, a molded article obtained from the resin composition of this embodiment can have high mechanical strength.

[0011] <Crystalline thermoplastic resin> The resin composition of the present embodiment contains a crystalline thermoplastic resin. By using a crystalline resin, a molded article having excellent chemical resistance can be obtained. A crystalline thermoplastic resin is a resin that has a definite melting point. Preferred examples of the crystalline thermoplastic resin used in this embodiment include crystalline thermoplastic polyester resin; polyamide resin; polyethylene resin; polyolefin resin such as polypropylene resin or cyclic cycloolefin resin; polyacetal resin; polyphenylene sulfide resin; polysulfone resin; and the like. It is more preferable that the resin contains at least one of a polyester resin and a polyamide resin, even more preferable that the resin contains a polyester resin, and even more preferable that the resin contains a polybutylene terephthalate resin.

[0012] In this embodiment, a preferred example of the crystalline thermoplastic resin is one that contains a polyester resin (preferably, a polybutylene terephthalate resin), and 90% by mass or more (preferably, 95% by mass or more) of the resin composition is a polyester resin (preferably, a polybutylene terephthalate resin). Another preferred example of the crystalline thermoplastic resin in this embodiment is one that contains a polyamide resin (preferably, a xylylenediamine-based polyamide resin described below), and 90% by mass or more (preferably, 95% by mass or more) of the resin composition is a polyamide resin (preferably, a xylylenediamine-based polyamide resin described below).

[0013] The resin composition of this embodiment may also be an alloy obtained by blending two or more crystalline thermoplastic resins. When two or more crystalline thermoplastic resins are blended, they are usually not completely compatible with each other, resulting in a sea-island structure. Carbon nanotubes are unlikely to be present in these island regions, resulting in a narrower region in the resin composition or electromagnetic wave absorber where carbon nanotubes are present. This allows various properties, such as electromagnetic wave absorption, to be effectively achieved even with a reduced amount of carbon nanotubes blended.

[0014] The resin composition of the present embodiment is preferably in the following blend form. The first blend form in this embodiment is a form containing polybutylene terephthalate resin (PBT) and polyethylene terephthalate resin (PET). The first blend form preferably contains 10 to 90 mass% of PBT and 90 to 10 mass% of PET. However, in the first blend form, of the resin components contained in the resin composition, the total of PBT and PET does not exceed 100 mass%, and is preferably 90 to 100 mass%. The second blend form in this embodiment is a form containing polybutylene terephthalate resin (PBT) and polyamide resin (PA). The second blend form preferably contains 10 to 90 mass% of PBT and 90 to 10 mass% of PA. However, in the second blend form, of the resin components contained in the resin composition, the total of PBT and PA does not exceed 100 mass%, and is preferably 90 to 100 mass%. Examples of polyamide resins include aliphatic polyamide resins, and polyamide 6 and polyamide 66 are preferred. A third blend form in this embodiment is a form containing polybutylene terephthalate resin (PBT) and polyethylene resin (PE). The third blend form preferably contains 10 to 90 mass% of PBT and 90 to 10 mass% of PE. However, in the third blend form, of the resin components contained in the resin composition, the total of PBT and PE does not exceed 100 mass%, and is preferably 90 to 100 mass%.

[0015] The resin composition of this embodiment may also contain an amorphous resin within the scope of the present invention. When the resin composition of this embodiment contains an amorphous resin, the content of the amorphous resin is preferably 0.1 to 40 mass %, may be 0.1 to 10 mass %, or may even be 0.1 to 5 mass %, of the crystalline resin. Each crystalline thermoplastic resin will be described in detail below.

[0016] <<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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] 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.

[0024] 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.

[0025] 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.

[0026] <<Polyamide resin>> Polyamide resins are polymers whose constituent units are acid amides obtained by ring-opening polymerization of lactams, polycondensation of aminocarboxylic acids, or polycondensation of diamines and dibasic acids. Specific 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 (described in detail below), polytrimethylhexamethylene terephthalamide, polybis(4-aminocyclohexyl)methanedodecamide, polybis(3-methyl-4-aminocyclohexyl)methanedodecamide, and polyundecamethylenehexahydroterephthalamide. The "I" in the above text represents the isophthalic acid component, and the "T" represents the terephthalic acid component. Regarding polyamide resins, the description in paragraphs 0011 to 0013 of JP-A No. 2011-132550 can be referred to, the contents of which are incorporated herein by reference.

[0027] The polyamide resin used in this embodiment contains 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.

[0028] 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.

[0029] 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.

[0030] The content of the crystalline 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 in the resin composition. By making the content equal to or greater than the lower limit, chemical resistance tends to be further improved. Furthermore, the content of the crystalline 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. By making the content equal to or less than the upper limit, the amount of warpage of the molded article tends to be more effectively reduced. The resin composition of the present embodiment may contain only one type of crystalline thermoplastic resin, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0031] <Carbon nanotubes> The resin composition of the present embodiment contains carbon nanotubes. By including carbon nanotubes, even a small amount of carbon nanotubes can effectively absorb electromagnetic waves. Furthermore, high flame retardancy can be achieved. The carbon nanotubes used in this embodiment may be single-walled carbon nanotubes, multi-walled carbon nanotubes, or a mixture thereof, but preferably contain multi-walled carbon nanotubes. Carbon materials partially having a carbon nanotube structure may also be used. Furthermore, 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. The carbon nanotubes may be blended in the form of a masterbatch, in which case the carbon nanotube content is preferably 5 to 30 mass %. Examples of resins used in the masterbatch include polyester resins (preferably polybutylene terephthalate resins).

[0032] The resin composition of this embodiment preferably contains 0.1 parts by mass or more of carbon nanotubes relative to 100 parts by mass of the crystalline 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 2.0 parts by mass or more, and particularly may be 2.4 parts by mass or more. By setting the content at or above the lower limit, electromagnetic wave absorption properties are effectively exhibited. Furthermore, the resin composition of this embodiment preferably contains 10.0 parts by mass or less of carbon nanotubes relative to 100 parts by mass of the crystalline 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. Setting the content at or below the upper limit tends to further shorten the combustion time in a combustion test. 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.

[0033] <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 (metal phosphinate, melamine polyphosphate, etc.), nitrogen-based flame retardants (melamine cyanurate, etc.), and metal hydroxides (magnesium hydroxide, etc.), with phosphorus-based flame retardants and halogen-based flame retardants being preferred. As phosphorus-based flame retardants, metal phosphinates are more preferred. As halogen-based flame retardants, bromine-based flame retardants are more preferred.

[0034] When a brominated flame retardant is used as the flame retardant, the type thereof is not particularly limited, 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.

[0035] The brominated phthalimide is preferably one represented by formula (1). [ka] (In formula (1), D represents an alkylene group, an arylene group, or a group formed by combining two or more of -S(=O)2-, -C(=O)-, and -O-. i is an integer of 1 to 4.)

[0036] In formula (1), D represents a group consisting of a combination of two or more of an alkylene group, an arylene group, -S(=O)2-, -C(=O)-, and -O-; a group consisting of a combination of an alkylene group or an arylene group with at least one of -S(=O)2-, -C(=O)-, and -O- is preferred; a group consisting of a combination of an alkylene group or an arylene group with one of -S(=O)2-, -C(=O)-, and -O- is more preferred; and an alkylene group is even more preferred. The group consisting of a combination of an alkylene group and -O- is intended to include, for example, a combination of two alkylene groups and one -O- (the same applies to other combinations). The alkylene group represented by D is preferably an alkylene group having 1 to 6 carbon atoms, more preferably a methylene group, an ethylene group, a propylene group or a butylene group. The arylene group is preferably a phenylene group. i is an integer of 1 to 4, and is preferably 4.

[0037] Examples of the brominated phthalimide 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.

[0038] The brominated phthalimide represented by formula (1) is preferably a brominated phthalimide represented by formula (2). [ka] (In formula (2), i is an integer of 1 to 4.) i is an integer of 1 to 4, and is preferably 4.

[0039] The brominated poly(meth)acrylate is preferably a polymer obtained by polymerizing a bromine atom-containing benzyl (meth)acrylate alone, copolymerizing two or more types of bromine atom-containing benzyl (meth)acrylate, or copolymerizing the bromine atom with another vinyl monomer. The bromine atoms are attached to benzene rings, and the number of bromine atoms attached is preferably 1 to 5, and more preferably 4 to 5, per benzene ring.

[0040] Examples of the benzyl acrylate containing a bromine atom include pentabromobenzyl acrylate, tetrabromobenzyl acrylate, tribromobenzyl acrylate, and mixtures thereof. Examples of the benzyl methacrylate containing a bromine atom include methacrylates corresponding to the above-mentioned acrylates.

[0041] Specific examples of other vinyl monomers that can be copolymerized with the bromine atom-containing benzyl (meth)acrylate include 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 anhydrides thereof such as styrene, acrylonitrile, fumaric acid, and maleic acid; vinyl acetate; and vinyl chloride.

[0042] These are usually used in an equimolar amount or less, particularly preferably 0.5 times or less, of the amount of benzyl (meth)acrylate containing a bromine atom.

[0043] Furthermore, vinyl monomers such as xylene diacrylate, xylene dimethacrylate, tetrabromxylene diacrylate, tetrabromxylene dimethacrylate, butadiene, isoprene, and divinylbenzene can also be used, and these can usually be used in an amount of 0.5 times or less by mole relative to the bromine atom-containing benzyl acrylate or benzyl methacrylate.

[0044] The brominated poly(meth)acrylate is preferably a polymer obtained by polymerizing a bromine atom-containing (meth)acrylate monomer, particularly benzyl (meth)acrylate, alone or by copolymerizing two or more of them, or by copolymerizing them with other vinyl monomers. The bromine atoms are attached to the benzene ring, and the number of bromine atoms attached is preferably 1 to 5, more preferably 4 to 5, per benzene ring.

[0045] As the brominated poly(meth)acrylate, pentabromobenzyl poly(meth)acrylate is preferred because of its high bromine content.

[0046] The molecular weight of the brominated poly(meth)acrylate is optional and may be appropriately selected and determined, but the weight-average molecular weight (Mw) is preferably 3,000 or more, 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. By setting the Mw at or above the lower limit, molded articles with higher mechanical strength tend to be obtained. 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. By setting the Mw at or below the upper limit, the flowability of the resin composition tends to be further improved.

[0047] The brominated polycarbonate preferably has a free bromine content of 0.05% by mass or more and preferably 0.20% by mass or less. By setting the content within these ranges, the heat resistance stability of the resin composition tends to be further improved. The brominated polycarbonate also preferably has a chlorine atom content of 0.001% by mass or more and preferably 0.20% by mass or less. By setting the content within these ranges, the mold corrosion resistance during molding tends to be further improved. Specifically, the brominated polycarbonate is preferably a brominated polycarbonate obtained from brominated bisphenol A, particularly tetrabromobisphenol A. Examples of the terminal structure include a phenyl group, a 4-t-butylphenyl group, and a 2,4,6-tribromophenyl group, and particularly, those having a 2,4,6-tribromophenyl group in the terminal group structure are preferred.

[0048] The average number of carbonate structural units in the brominated polycarbonate may be appropriately selected and determined, but is preferably 2-30, more preferably 3-15, and even more preferably 3-10.

[0049] The molecular weight of the brominated polycarbonate is optional and may be appropriately selected and determined, but preferably has a viscosity average molecular weight of 1,000 to 20,000, more preferably 2,000 to 10,000.

[0050] The brominated polycarbonate obtained from the above brominated bisphenol A can be obtained, for example, by a conventional method of reacting brominated bisphenol with phosgene. The end-capping agent includes an aromatic monohydroxy compound, which may be substituted with a halogen or an organic group.

[0051] Specific preferred examples of the brominated epoxy include bisphenol A type brominated epoxy compounds, such as tetrabromobisphenol A epoxy compounds and glycidyl brominated bisphenol A epoxy compounds.

[0052] The molecular weight of the brominated epoxy compound is optional and may be appropriately selected and determined. However, the weight average molecular weight (Mw) is preferably 3,000 or more, 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. By setting the weight average molecular weight at or above the lower limit, a molded product having higher mechanical strength tends to be obtained. 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. By setting the weight average molecular weight at or below the upper limit, the flowability of the resin composition tends to be further improved. 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.

[0053] Brominated epoxy oligomers can also be used in combination with the brominated epoxy. In this case, for example, by using an oligomer with an Mw of 5,000 or less in a proportion of about 50% by mass or less, flame retardancy, mold releasability, and flowability can be appropriately adjusted. The bromine atom content in the brominated epoxy compound is optional, but to provide sufficient flame retardancy, it is usually 10% by mass or more, preferably 20% by mass or more, and particularly preferably 30% by mass or more. The upper limit is 60% by mass, and preferably 55% by mass or less.

[0054] The brominated polystyrene preferably includes a brominated polystyrene containing a constitutional unit represented by formula (3). [ka] (In formula (3), t is an integer of 1 to 5, and n is the number of constitutional units.)

[0055] Brominated polystyrene can be produced by either brominating polystyrene or polymerizing brominated styrene monomers. Polymerization of brominated styrene is preferred because it contains a smaller amount of free bromine atoms. In formula (3), the CH group to which the brominated benzene is bonded may be substituted with a methyl group. Brominated polystyrene may also be a copolymer copolymerized with 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 be used alone or as a mixture of two or more different structures, and may contain units derived from styrene monomers with different bromine numbers in a single molecular chain.

[0056] Specific examples of brominated polystyrene include 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 of suitable styrene copolymers include poly(2,4-dibromostyrene), 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), and 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 are particularly preferred.

[0057] The brominated polystyrene preferably has the number n (average degree of polymerization) of structural units in formula (3) 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, poor dispersion is likely to occur and mechanical properties are likely to deteriorate. 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, in the case of the brominated polystyrene described above, the weight average molecular weight (Mw) is preferably 50,000 to 70,000, and in the case of brominated polystyrene obtained by polymerization, the weight average molecular weight (Mw) is preferably about 10,000 to 30,000. The weight average molecular weight (Mw) can be determined as a value converted into standard polystyrene by GPC measurement.

[0058] 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. By setting the bromine concentration at or above the lower limit, the flame retardancy of the molded article tends to be effectively improved. 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.

[0059] When a metal phosphinate is used as a flame retardant, the type thereof is not particularly limited, but it is preferable that the metal phosphinate has an anion portion represented by formula (4) or (5) and a metal ion of the cation portion is any of calcium, magnesium, aluminum, and zinc.

[0060] [ka] (In the formula, R 1 and R 2 each independently represents an alkyl group having 1 to 6 carbon atoms or an aryl group which may have a substituent, and R 1 may be the same or different, and R 3 represents an alkylene group having 1 to 10 carbon atoms, an arylene group which may have a substituent, or a group consisting of a combination thereof; R 3 may be the same or different, and n represents an integer of 0 to 2.) The aryl group which may have a substituent is preferably a phenyl group which may have a substituent. When it has a substituent, it is preferably an alkyl group having 1 to 3 carbon atoms. It is also preferably unsubstituted. The arylene group which may have a substituent is preferably a phenylene group which may have a substituent. The arylene group which may have a substituent is preferably unsubstituted or has an alkyl group having 1 to 3 carbon atoms (preferably a methyl group) as a substituent. In this embodiment, a metal phosphinate represented by formula (5) is preferred. Also, in this embodiment, aluminum phosphinate is preferred.

[0061] Specific examples of the metal phosphinate 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, and calcium methanedi(methylphosphinate). Examples of suitable methyl phenyl phosphates include magnesium methane di(methylphosphinate), aluminum methane bis(methylphosphinate), zinc methane bis(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. For details about the metal phosphinate, please refer to paragraphs 0052 to 0058 of WO 2010 / 010669, the contents of which are incorporated herein by reference.

[0062] The content of the flame retardant 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, relative to 100 parts by mass of the crystalline thermoplastic resin. By setting the content at or above the lower limit, the flame retardancy of the resulting molded article tends to be further improved. The upper limit of the content of the flame retardant 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, relative to 100 parts by mass of the thermoplastic resin. By setting the content at or below the upper limit, the decrease in the mechanical strength of the resulting molded article can be more effectively suppressed. The resin composition of the present embodiment may contain only one type of flame retardant, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0063] <Flame retardant synergist> The resin composition of this embodiment may contain a flame retardant aid. By including a flame retardant aid, the flame retardancy of the molded article can be further improved. The flame retardant aid is particularly preferably used when a halogen-based flame retardant is included. Examples of the flame retardant aid used in this embodiment include antimony compounds, such as antimony trioxide (Sb2O3), antimony pentoxide (Sb2O5), and sodium antimonate. In particular, antimony oxide, and especially antimony trioxide, is preferred from the viewpoint of impact resistance. When a flame retardant aid is blended, it may be blended as a masterbatch. The content of the antimony compound in the masterbatch is preferably 30 to 90 mass %, more preferably 40 to 85 mass %, and even more preferably 50 to 85 mass %. When the resin composition of this embodiment contains a flame retardant aid (e.g., an antimony compound), the content thereof is preferably 0.1 parts by mass or more, more preferably 1.0 parts 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, relative to 100 parts by mass of the crystalline thermoplastic resin. By setting the content at or above the lower limit, flame retardancy tends to be more effectively exhibited. Furthermore, the upper limit of the content of the antimony compound 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, relative to 100 parts by mass of the crystalline thermoplastic resin. By setting the content at or below the upper limit, the mold releasability and impact resistance of the resulting molded article tend to be improved. The resin composition of the present embodiment may contain only one type of flame retardant auxiliary (for example, an antimony compound), or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0064] <Reinforcement material> The resin composition of the present embodiment may contain a reinforcing material, which can improve the mechanical strength of the resulting molded article. 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.

[0065] 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).

[0066] 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.

[0067] 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.

[0068] 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.

[0069] The resin composition of this embodiment preferably contains 10 parts by mass or more of a reinforcing material (preferably glass fiber) relative to 100 parts by mass of a crystalline 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. By setting the content at or above the lower limit, the mechanical strength of the resulting molded article tends to be further increased. Furthermore, the content of the reinforcing material (preferably glass fiber) relative to 100 parts by mass of a crystalline thermoplastic resin (preferably polybutylene terephthalate resin) 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. 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.

[0070] The content of the reinforcing material (preferably glass fiber) 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 in the resin composition. 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 flowability of the resin composition 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.

[0071] <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 various resin additives. Note that the other components may be contained alone or in any combination and ratio of two or more. Specific examples include reactive compounds, stabilizers, release agents, anti-dripping agents, pigments, dyes, UV absorbers, antistatic agents, anti-fogging agents, anti-blocking agents, flow improvers, plasticizers, dispersants, antibacterial agents, etc. The resin composition of the present embodiment preferably contains at least one of stabilizers and release agents. The resin composition of this embodiment is prepared so that the total of the crystalline thermoplastic resin (preferably polybutylene terephthalate resin), carbon nanotubes, flame retardant, and other optional components is 100% by mass. In the resin composition of this embodiment, the total of the crystalline thermoplastic resin (preferably polybutylene terephthalate resin), carbon nanotubes, flame retardant, and reinforcing material (preferably glass fiber) preferably accounts for 95% by mass or more of the resin composition. Furthermore, in the resin composition of this embodiment, the total of the crystalline thermoplastic resin (preferably polybutylene terephthalate resin), carbon nanotubes, flame retardant, reinforcing material (preferably glass fiber), stabilizer, mold release agent, and reactive compound (preferably epoxy compound) preferably accounts for 99% by mass or more of the resin composition.

[0072] <<Reactive compounds>> The resin composition of the present embodiment preferably contains a reactive compound. By containing the reactive compound, the mechanical strength is improved and a resin composition having excellent hydrolysis resistance is obtained. The reactive compound here does not contain bromine. The reactive compound used in the present embodiment preferably includes at least one selected from the group consisting of a compound having an epoxy group, a carbodiimide compound, a compound having an oxazoline group, and a compound having an oxazine group, and more preferably includes a compound having an epoxy group.

[0073] The compound having an epoxy group is a compound having one or more epoxy groups in one molecule, and examples thereof include a glycidyl compound, an aromatic ring-containing compound having an epoxy group, and an alicyclic compound having an epoxy group, and it is preferable that the compound contains at least an aromatic ring-containing compound having an epoxy group.

[0074] Specific examples of compounds having an epoxy group 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 having an aromatic ring such as benzoic acid glycidyl ester, terephthalic acid diglycidyl ester, orthophthalic acid diglycidyl ester, methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, decyl glycidyl ether, stearyl glycidyl ether, (di)glycidyl ethers such as glycidyl ether, 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 sorbic acid glycidyl ester, adipic acid diglycidyl ester, 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 chains, bisphenol A type epoxy compounds, novolac type epoxy compounds, bisphenol F type epoxy compounds, biphenyl type epoxy compounds, etc. are preferred, and bisphenol A type epoxy compounds are more preferred.

[0075] 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, relative to 100 parts by mass of the crystalline thermoplastic resin (preferably polybutylene terephthalate resin). By setting the content at or above the lower limit, hydrolysis resistance tends to be further improved. 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, relative to 100 parts by mass of the crystalline thermoplastic resin (preferably polybutylene terephthalate resin). By setting the content at or below the upper limit, the melt viscosity tends to be more stable and moldability tends to be improved. The resin composition of the present embodiment may contain only one type of reactive compound, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0076] <<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.

[0077] The resin composition of this embodiment preferably contains 0.01 parts by mass or more of the stabilizer relative to 100 parts by mass of the crystalline thermoplastic resin, 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 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 relative to 100 parts by mass of the crystalline thermoplastic resin. 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.

[0078] <<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.

[0079] 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 crystalline thermoplastic resin, 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 relative to 100 parts by mass of the crystalline thermoplastic resin 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. 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.

[0080] The resin composition of the present embodiment may or may not contain one or more carbon-based electromagnetic wave absorbing materials other than carbon nanotubes. The resin composition of this embodiment preferably does not contain any carbon-based electromagnetic wave absorbing material other than carbon nanotubes, or contains less than 3 mass % of the carbon-based electromagnetic wave absorbing material other than carbon nanotubes. By adopting such a configuration, the frequency dependency of the reflectance of electromagnetic waves 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.

[0081] The resin composition of this embodiment preferably does not contain carbon fibers or has a carbon fiber content of less than 3 mass %. This configuration tends to further improve the frequency dependency of the electromagnetic wave reflectance. Furthermore, the electromagnetic wave reflectance can be further reduced. 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.

[0082] The resin composition of this embodiment preferably does not contain graphite or has a graphite content of less than 3 mass %. This configuration tends to further improve the frequency dependency of the reflectance of electromagnetic waves. It also increases the absorption rate of electromagnetic waves. Furthermore, it further improves 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.

[0083] The resin composition of this embodiment preferably does not contain carbon black or has a carbon black content of less than 3% by mass. This configuration tends to further improve the frequency dependence of the reflectance of electromagnetic waves. Furthermore, the mechanical strength of the resulting molded article can be further improved. 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.

[0084] The resin composition of this embodiment preferably does not contain Ketjen black or the Ketjen black content is less than 3 mass %. This configuration tends to further improve the frequency dependency of the reflectance of electromagnetic waves. In addition, the mechanical strength of the resulting molded article can be further improved. The content of the Ketjen Black 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.

[0085] The resin composition of this embodiment may contain a flame retardant other than a brominated flame retardant (for example, a phosphorus-based flame retardant), but is preferably substantially free of flame retardants other than a brominated flame retardant. "Substantially free" means that the content of flame retardants other than a brominated flame retardant is 10% by mass or less of the content of the brominated flame retardant, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. Another example of the resin composition of this embodiment is one that is substantially free of flame retardants other than the metal phosphinate (for example, halogen-based flame retardants). "Substantially free" means that the content of flame retardants other than the metal phosphinate is 10% by mass or less of the content of the metal phosphinate, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0086] <Physical properties of resin composition> The resin composition of the present embodiment preferably has excellent flame retardancy. Specifically, the resin composition of this embodiment is molded into a test piece having a thickness of 0.8 mm, and the flame retardancy according to the UL94 combustion test is preferably rated as V-0 or V-1, and more preferably V-0.

[0087] The resin composition of this embodiment has electromagnetic wave absorbing properties. Specifically, the resin composition of this embodiment, when molded into a 2 mm thick piece (for example, 100 mm×100 mm×2 mm), has an absorptivity of 40.0 to 100% at a frequency of 76.5 GHz as determined according to formula (A). Formula (A)

number

[0088] The absorbency is preferably 50.0% or more, more preferably 55.0% or more, even more preferably 60.0% or more, and even more preferably 65.0% or more. The upper limit is ideally 100%, but even if it is 90.0% or less, the required performance is sufficiently met.

[0089] 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 determined according to formula (B) when molded into a 2 mm thick piece (for example, 100 mm x 100 mm x 2 mm). Formula (B)

number

[0090] 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 if it is 1.0% or more, the required performance is sufficiently met.

[0091] 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 when molded into a 2 mm thick piece (for example, 100 mm×100 mm×2 mm) at a frequency of 76.5 GHz, as determined according to formula (C). Formula (C)

number

[0092] The transmittance is preferably less than 25.0%, more preferably less than 20.0%, even more preferably 19.0% or less, still 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 if it is 0.5% or more, the required performance is sufficiently met.

[0093] The test piece for measuring the absorptance, reflectance and transmittance will give substantially the same values ​​even if it is 150 mm x 150 mm x 2 mm. The resin composition of the present embodiment preferably satisfies at least two of the following, and more preferably satisfies all of the following: absorbance calculated according to the above formula (A), reflectance calculated according to the above formula (B), and transmittance calculated according to the above formula (C).

[0094] The resin composition of the present embodiment preferably has excellent tensile properties. Specifically, 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 50 MPa or more, more preferably 60 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 according to ISO 527-1 and ISO 527-2 is preferably 2,000 MPa or more, more preferably 2,500 MPa or more, and even more preferably 9,000 PMa or more. The upper limit of the tensile modulus is not particularly specified, but, for example, 14,000 MPa or less is practical.

[0095] 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, 280 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, and even more preferably 10,000 PMa or more. The upper limit of the flexural modulus is not particularly specified, but for example, 14,000 MPa or less is practical.

[0096] 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 tensile test piece (4 mm thick), the notched Charpy impact strength according to the ISO179 standard is 4.0 kJ / m 2 Preferably, it is 5.0 kJ / m or more. 2 The upper limit of the notched Charpy impact strength is not particularly limited, but is, for example, 20.0 kJ / m 2 or less, and even 12.0 kJ / m 2 It may be the following:

[0097] The resin composition of this embodiment also has a surface resistance of 1.0×10 when molded into a size of 100 mm×100 mm×2 mm according to IEC 60093. 11 Ω or more, and 1.0 × 10 16 It is preferably Ω or less. The resin composition of the present embodiment further has a volume resistivity of 1.0×10 when molded into a size of 100 mm×100 mm×2 mm according to IEC 60093. 10 It is preferable that the resistivity is Ω·cm or more, and 1.0×10 17 It is preferable that the resistivity is Ω·cm or less. The details of the various measurement methods mentioned above are described in the Examples.

[0098] <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, by feeding a crystalline thermoplastic resin (preferably a polybutylene terephthalate resin), carbon nanotubes, a flame retardant, and optionally other components into an extruder and melt-kneading them. The components may be premixed and fed to the extruder all at once, or the components may be premixed without premixing or only a portion of the components may be premixed and fed to the extruder using a feeder. The extruder may be a single-screw extruder or a twin-screw extruder. Alternatively, a portion of the components, such as carbon nanotubes, may be melt-kneaded with a resin component (e.g., polybutylene terephthalate resin) to prepare a masterbatch, which may then be blended with the remaining components and melt-kneaded. Furthermore, it is preferable that the reinforcing material (for example, glass fiber) is 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.

[0099] <Method of manufacturing molded body> The method for producing the molded article is not particularly limited, and any molding method generally 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 or other 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., among which injection molding is preferred.

[0100] <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 in an electromagnetic wave absorber (also referred to as an electromagnetic wave absorbing member), more preferably for use in an electromagnetic wave absorber having a frequency of at least 60 to 90 GHz, and even more preferably for use in 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]

[0101] 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.

[0102] raw material The following raw materials were used: In the table below, PBT means polybutylene terephthalate resin. [Table 1]

[0103] Examples 1 to 5, Comparative Examples 1 to 6 <Production of Resin Composition (Pellets)> The components listed in Tables 2 and 3 were placed in a stainless steel tumbler and mixed for 1 hour. The resulting mixture was fed through the main feed port into an intermeshing co-rotating twin-screw extruder (Japan Steel Works, Ltd., "TEX-30α," screw diameter 32 mm, L / D = 42). The barrel temperature of the first kneading section was set to 260°C (280°C for Comparative Examples 5 and 6) for plasticization. The reinforcing material (glass fiber) was fed through a side feeder at the ratio listed in Tables 2 and 3. The barrel temperature after adding the reinforcing material was set to 250°C (280°C for Comparative Examples 5 and 6). The mixture was melt-kneaded at a discharge rate of 40 kg / h and a screw rotation speed of 200 rpm, and 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).

[0104] <UL94 flammability test> The pellets obtained above were dried at 120°C for 5 hours, and then injection molded in an injection molding machine ("J50" manufactured by The Japan Steel Works, Ltd.) at a cylinder setting temperature of 260°C (280°C for Comparative Examples 5 and 6) and a mold temperature of 80°C to obtain test pieces measuring 125 mm x 13 mm x 0.8 mm thick. Using the obtained test pieces, the dripping during combustion and the burning time were measured and evaluated based on the flammability test UL94.

[0105] <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 (280°C for Comparative Examples 5 and 6) 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.

[0106] <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 (280°C for Comparative Examples 5 and 6) 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.

[0107] <Charpy notched impact strength> The pellets obtained by the above manufacturing method were dried at 120°C for 5 hours, and then injection-molded into ISO tensile test specimens (4 mm thick) using an injection molding machine ("J85AD" manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 250°C and a mold temperature of 80°C. However, in Comparative Examples 5 and 6, the cylinder temperature was (280)°C and the mold temperature was 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.

[0108] <Absorption rate, transmittance, reflectance> 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 (280°C for Comparative Examples 5 and 6) 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 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

[0109] Formula (B)

number

[0110] Formula (C)

number

[0111] <Electromagnetic wave absorption performance evaluation> The electromagnetic wave absorption performance was evaluated as follows: A if all three of the absorbance, reflectance, and transmittance were satisfied; B if at least the absorbance met the following criteria (except for cases that fell under A); and C if neither A nor B was satisfied. Judgment criteria Absorption rate is 50.0% or more Reflectivity less than 30.0% Transmittance less than 25.0%

[0112] <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 (270°C for Comparative Examples 5 and 6) 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.

[0113] <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 (270°C for Comparative Examples 5 and 6) 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.

[0114] <Chemical resistance> A jig capable of applying a three-way bending load, as shown in Figure 1, was used in an environment with a temperature of 23°C. The ISO multipurpose test specimen (4 mm thick) obtained above (reference numeral 1 in Figure 1) was attached to the lower center of the test specimen attachment jig 2. An adjustment cylinder 3 for adjusting the amount of strain was attached to the test specimen attachment jig 2 and fixed with a super screw 4, adjusting and fixing the amount of strain to 1%. The distance between the adjustment cylinders 3 was 100 mm. A 10 mm x 20 mm piece of gauze soaked in regular gasoline was placed in the center of the fixed test specimen. After 24 hours, the condition of the test specimen was visually inspected and evaluated according to the following criteria. A: No cracks or other problems occurred. B: Cracks or breakage.

[0115] [Table 2] [Table 3]

[0116] In Tables 2 and 3, the carbon nanotubes in (b-1) indicate the amount of carbon nanotubes themselves, not the amount of master batch added. The molded article formed from the resin composition of the present invention had high absorbency, excellent flame retardancy and chemical resistance, and high mechanical strength. In addition, the molded article formed from the resin composition of the present invention had low transmittance and reflectance. In contrast, the resin compositions of the comparative examples had low absorption rates and were inferior in flame retardancy or chemical resistance. In particular, the amorphous resins of Comparative Examples 5 and 6 did not achieve the same electromagnetic wave absorption properties as the crystalline resins, even though they contained the same amount of CNTs. [Industrial Applicability]

[0117] In millimeter-wave radar, not only transmitted electromagnetic waves but also reflected electromagnetic waves become noise and cause malfunctions. Therefore, there is an increasing demand for materials with high electromagnetic wave absorption and low transmittance and reflectance. The resin composition of the present invention can meet these demands. Furthermore, it can also meet the requirements for high flame retardancy and chemical resistance. Therefore, it is expected to be widely used in applications requiring flame retardancy, chemical resistance, and electromagnetic wave absorption properties. [Explanation of symbols]

[0118] 1 ISO Multipurpose Test Block 2 Test specimen mounting jig 3 Adjustment cylinder for adjusting the amount of distortion 4 Super Screw

Claims

1. A crystalline thermoplastic resin, carbon nanotubes, and a flame retardant are included. When molded to a thickness of 2 mm, the absorption rate calculated according to formula (A) at a frequency of 76.5 GHz is 40.0 to 100%, the crystalline thermoplastic resin comprises a polyester resin; Furthermore, when the flame retardant contains a halogen-based flame retardant, it contains a flame retardant synergist, the content of the carbon nanotubes is 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the crystalline thermoplastic resin, the content of the flame retardant is 1.0 part by mass or more and 30.0 parts by mass or less relative to 100 parts by mass of the crystalline thermoplastic resin, The resin composition, when containing the flame retardant aid, has a content of 0.1 parts by mass or more and 20.0 parts by mass or less relative to 100 parts by mass of the crystalline thermoplastic resin, The resin composition is molded into a test piece having a thickness of 0.8 mm, and the flame retardancy according to the UL94 combustion test is determined to be V-0 or V-1. 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.)

2. The resin composition according to claim 1 , further comprising a reinforcing material.

3. The resin composition of claim 2 , wherein the reinforcing material comprises glass fibers.

4. The resin composition according to any one of claims 1 to 3, wherein the crystalline thermoplastic resin comprises a polybutylene terephthalate resin.

5. The resin composition according to any one of claims 1 to 4, wherein the carbon nanotubes are contained in an amount of 0.1 to 10.0 parts by mass per 100 parts by mass of the crystalline thermoplastic resin.

6. The resin composition according to any one of claims 1 to 5, wherein the carbon nanotubes include multi-walled carbon nanotubes.

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

8. An electromagnetic wave absorber formed from the resin composition according to any one of claims 1 to 6.

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