Electromagnetic wave-absorbing composition containing thermoplastic resin or thermoplastic elastomer, and molded article comprising same

Abstract

The present invention addresses the problem of providing an electromagnetic wave-absorbing composition which contains a thermoplastic resin or a thermoplastic elastomer, has electromagnetic wave-absorbing properties, and is capable of suppressing an increase in fluidity during heating. This electromagnetic wave-absorbing composition is characterized by containing at least one component (A) selected from the group consisting of thermoplastic resins and thermoplastic elastomers and a component (B), which is an Fe-Cr-Si-based soft magnetic metal powder, in a mass ratio (component (A) / component (B)) of 5 / 95 to 80 / 20, and by further containing an amount of at least one component (A), which is at least one component (B), per 100 parts by mass of the total of the component (A) and the component (B), with respect to 100 parts by mass of the total of the component (A) and the component (B). At least one component (C) selected from among phosphite ester compounds and phosphate ester compounds is contained in an amount of 0.02-1.4 parts by mass, and the electromagnetic wave absorption energy P at 79 GHz is 5 kw / m3 or more.

Description

Technical Field

[0001] The present invention relates to an electromagnetic wave absorbing composition capable of suppressing an increase in fluidity during heating. Background Art

[0002] In a high-frequency communication device having a processing circuit that processes and outputs an input signal, in order to avoid the influence of external electromagnetic waves on the processed signal and to prevent electromagnetic waves from leaking from inside the high-frequency communication device to the outside, the processing circuit is usually housed in a metal casing. At this time, electromagnetic waves propagate and resonate inside the casing, which may cause coupling (electromagnetic coupling) between the input signal and the output signal, leading to problems. The metal material constituting the wall surface of the casing promotes such coupling. In particular, with the high-frequencyization of the communication frequency, this problem becomes more prominent.

[0003] In a high-frequency communication device, as a means for reducing signal coupling between circuits such as between an input signal and an output signal, it is generally known to provide a sheet-like electromagnetic wave absorber on the inner surface of a metal casing.

[0004] In Patent Document 1, as an example of an electromagnetic wave absorber, an Fe-7Cr-9Al alloy powder as a soft magnetic metal is mixed in chlorinated polyethylene rubber in an amount of 15 to 45% by volume, and the mixture is rolled into a sheet having a thickness of 0.5 to 1.5 mm, and it is disclosed that it has a coupling prevention effect between the input side and the output side in the range of 9 to 12 GHz.

[0005] In Patent Document 2, a sheet obtained by mixing an Fe-Cr-Si-based alloy powder into an acrylic resin or a silicone resin is listed as an electromagnetic wave absorber in the range of 1 to 100 GHz, and it is disclosed that it also has good electromagnetic wave attenuation characteristics for high-frequency electromagnetic waves.

[0006] Thus, in an electromagnetic wave absorber for a communication device, although a sheet is usually attached to a necessary position such as a casing, the sheet attachment process is relatively complicated because it involves an attachment process of applying an adhesive to a metal casing. Therefore, there is a need to achieve sheetless formation by integrally insert-molding an electromagnetic wave absorbing resin material with a metal casing, or by resinizing the metal casing itself to impart electromagnetic wave absorption performance.

[0007] In Patent Document 3, an example of an electromagnetic wave absorbing injection molding resin is described, and it is disclosed that by containing an Fe-Si-Al alloy powder having a specified median diameter and aspect ratio in a polyamide resin, magnetic wave shielding in the frequency range of 0.1 to 100 MHz is imparted. Prior Art Documents Patent Documents

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-164687 Patent Document 2: Japanese Patent No. 6859652 Patent Document 3: Japanese Patent Application Laid-Open No. 2012-151205 Summary of the Invention Problems to be Solved by the Invention

[0009] However, as disclosed in Patent Document 3, it has been found that in a composition containing a thermoplastic resin or a thermoplastic elastomer and soft magnetic metal powder, a phenomenon of increased fluidity accompanied by heating can be observed. When the fluidity increases, there are cases where overfilling occurs during molding, which has a negative impact on the mass productivity of the resulting molded product.

[0010] Therefore, an object of the present invention is to provide an electromagnetic wave absorbing composition, which is a composition containing a thermoplastic resin or a thermoplastic elastomer, has electromagnetic wave absorption performance, and can suppress the increase in fluidity during heating. Technical Means for Solving the Problems

[0011] In order to solve the above problems, the present inventors conducted repeated and in-depth studies. As a result, it was found that by adding at least one selected from a specified phosphite compound and a phosphate compound when a thermoplastic resin or a thermoplastic elastomer contains Fe—Cr—Si-based soft magnetic metal powder, it is possible to suppress the increase in fluidity during heating while maintaining the electromagnetic wave absorption performance, thereby completing the present invention. More specifically, the present invention provides the following.

[0012] [1] An electromagnetic wave absorbing composition, characterized in that it contains at least one selected from a thermoplastic resin and a thermoplastic elastomer as component (A) and Fe—Cr—Si-based soft magnetic metal powder as component (B) in a mass ratio ((A) component / (B) component) in the range of 5 / 95 to 80 / 20, furthermore, with respect to a total of 100 parts by mass of the component (A) and the component (B), it contains at least one selected from a phosphite compound and a phosphate compound in an amount of 0.02 to 1.4 parts by mass as component (C), the electromagnetic wave absorption energy P shown in the formula (1) is 5 kW / m 3 or more at 79 GHz. [Equation 1] [In the formula (1), P represents the electromagnetic wave absorption energy (W / m 3 ), μ 0 represents the vacuum permeability (H / m), μ r " represents the loss term of the complex relative permeability, ε0 represents the vacuum permittivity (F / m), ε r ” represents the loss term of the complex relative permittivity, ρ represents the resistivity (Ωm), H represents the magnetic field strength (A / m), E represents the electric field strength (V / m), and f represents the frequency (Hz).] [2] The electromagnetic wave absorbing composition according to [1], wherein, when measured according to ISO1133, the ΔMFR obtained according to the following formula is 50 g / 10 min or less. ΔMFR = (MFR at 20 - minute residence) - (MFR at 5 - minute residence) (In the formula, the MFR at 20 - minute residence refers to the melt flow rate measured with a pre - heating time of 20 minutes, and the MFR at 5 - minute residence refers to the melt flow rate measured with a pre - heating time of 5 minutes. Among them, the load during the melt flow rate measurement is 2160 g, and the measurement temperature is the melting point of component (A)+25 °C.) [3] The electromagnetic wave absorbing composition according to [1] or [2], wherein the component (A) contains one or more selected from polyester - based resins, polyester elastomers, polycarbonate - based resins, polyamide - based resins, polyphenylene sulfide - based resins, and polyolefin - based resins. [4] The electromagnetic wave absorbing composition according to any one of [1] to [3], wherein the component (B) contains 1.0 to 21.0% by mass of Cr, 0.5 to 10.0% by mass of Si, 0 to 3.0% by mass of Mo, and the balance is composed of Fe and impurities. [5] The electromagnetic wave absorbing composition according to any one of [1] to [4], wherein the average particle size D50 of the component (B) is 3 to 15 μm. [6] A molded article comprising the electromagnetic wave absorbing composition according to any one of [1] to [5]. Effects of the Invention

[0013] According to the present invention, by mixing a specific amount of component (C) which is at least one selected from phosphite - based compounds and phosphate - based compounds into component (A) which is at least one selected from thermoplastic resins and thermoplastic elastomers and component (B) which is Fe - Cr - Si - based soft magnetic metal powder, a composition with excellent electromagnetic wave absorption performance and capable of suppressing the increase in fluidity during heating can be obtained. Detailed Embodiments

[0014] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to any of the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, regarding parts that are repeatedly described, although there are cases where appropriate descriptions are omitted, the gist of the present invention is not limited.

[0015] [Component (A)] In the electromagnetic wave absorbing composition of the present invention, the component (A) used as the base component (matrix component) is at least one selected from thermoplastic resins and thermoplastic elastomers.

[0016] As the thermoplastic resin, there is no particular limitation, and typically, polyester resins, polycarbonate resins, polyamide resins, polyphenylene sulfide resins, polyolefin resins, etc. can be cited. These thermoplastic resins can be used alone or in combination of two or more.

[0017] As the thermoplastic elastomer, there is no particular limitation, and typically, polyester elastomers can be cited.

[0018] The component (A) can be used alone or in combination of two or more.

[0019] Among the component (A), resins and / or elastomers having an ester skeleton and / or an amide skeleton in the main chain repeating unit part (hereinafter referred to as ester - amide - based resins and / or elastomers), such as polyester - based resins, polyester elastomers, polycarbonate - based resins, polyamide - based resins, etc., are particularly preferred, and resins and / or elastomers having an ester skeleton in the main chain repeating unit part (hereinafter referred to as ester - based resins and / or elastomers) are more preferred. When the component (A) (especially ester - amide - based resins and / or elastomers) is melt - kneaded with the soft magnetic metal powder as the component (B), heating will easily increase its fluidity. However, in the present invention, by making at least one selected from phosphite - based compounds and phosphate - based compounds co - exist as the component (C), an increase in fluidity can be suppressed.

[0020] As the component (A), ester - amide - based resins and / or elastomers are preferred, at least one selected from polyester - based resins (excluding liquid crystal polyester - based resins), polyamide - based resins, and polyester elastomers is more preferred, at least one selected from polyester - based resins (excluding liquid crystal polyester - based resins) and polyester elastomers is further preferred, and polyester - based resins (excluding liquid crystal polyester - based resins) are particularly preferred. Polyester - based resins (excluding liquid crystal polyester - based resins) and polyester elastomers have a low water absorption rate, which is useful for making the size stability of the obtained molded product good.

[0021] As the polyester - based resin, an aromatic polyester resin having an aromatic dicarboxylic acid unit and a glycol unit as structural units is preferred.

[0022] The aromatic dicarboxylic acid constituting the above structural unit is not particularly limited, but specific examples include: benzene dicarboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid; naphthalene dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid and 1,5-naphthalenedicarboxylic acid; compounds having two carboxyl phenyl groups such as 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid and diphenyl-p,p-dicarboxylic acid, and functional derivatives thereof. These aromatic dicarboxylic acids can be used alone or in combination of two or more. As the aromatic dicarboxylic acid constituting the above structural unit, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and diphenyl-p,p-dicarboxylic acid are preferred, as these tend to have a fast crystallization rate and good formability. Particularly preferred are benzene dicarboxylic acids such as terephthalic acid and isophthalic acid, and naphthalene dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid.

[0023] In addition, the above aromatic dicarboxylic acid unit is introduced by, for example, ester synthesis using an aromatic dicarboxylic acid, an aromatic dicarboxylic acid ester, or a salt thereof as a raw material. Examples of the aromatic dicarboxylic acid ester constituting the raw material include: monoalkyl esters of aromatic dicarboxylic acids and dialkyl esters of aromatic dicarboxylic acids, and dialkyl esters of aromatic dicarboxylic acids are preferred. Preferred raw materials are terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,6-naphthalenedicarboxylic acid, and dimethyl 2,6-naphthalenedicarboxylate.

[0024] Furthermore, in the aromatic polyester resin, part of the aromatic dicarboxylic acid units can be replaced with dicarboxylic acid units other than aromatic dicarboxylic acid units (hereinafter referred to as other dicarboxylic acid units). Examples of the other dicarboxylic acid constituting the above other dicarboxylic acid unit include: saturated or unsaturated aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, glutaric acid, 1,10-decanedicarboxylic acid, and dimer acid, or functional derivatives thereof; alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid, and cyclohexanedicarboxylic acid, or functional derivatives thereof. For the other dicarboxylic acid units, in the total of the aromatic dicarboxylic acid units and the other dicarboxylic acid units (total dicarboxylic acid units), it is preferably less than 50 mol%, more preferably less than 40 mol%, and further preferably less than 30 mol%. When the above amount is less than 50 mol%, the polyester resin tends to have good crystallinity, and the formability and heat resistance become better.

[0025] The above diol (unit) constituting the aromatic polyester is not particularly limited, and specifically includes: aliphatic diols such as alkylene diols (e.g., ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol); alicyclic diols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediol; aromatic diols such as bisphenol A, hydroquinone, and 2,2-bis(4-β-hydroxyethoxyphenyl)propane. These diol (units) can be used alone or in combination of two or more. As the above diol (unit), it is preferably at least one selected from aliphatic diols and alicyclic diols, more preferably alkylene diols having 2 to 8 carbon atoms. More specifically, it is at least one selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol, and more preferably at least one of ethylene glycol and 1,4-butanediol.

[0026] As the aromatic polyester resin, specifically, the following can be cited: polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, poly(1,4-cyclohexanedimethylene terephthalate), poly(hexamethylene terephthalate), polyethylene naphthalate, polytrimethylene naphthalate, polybutylene naphthalate, ethylene glycol / isophthalic acid terephthalate copolymer, trimethylene glycol / isophthalic acid terephthalate copolymer, butylene glycol / isophthalic acid terephthalate copolymer, ethylene glycol / terephthalic acid / naphthalic acid copolymer, trimethylene glycol / terephthalic acid / naphthalic acid copolymer, butylene glycol / terephthalic acid / naphthalic acid copolymer, butylene glycol / sebacic acid terephthalate copolymer, 1,4-cyclohexanedimethanol / ethylene glycol terephthalate copolymer, ethylene glycol / succinic acid terephthalate copolymer, trimethylene glycol / succinic acid terephthalate copolymer, butylene glycol / succinic acid terephthalate copolymer, ethylene glycol / adipic acid terephthalate copolymer, trimethylene glycol / adipic acid terephthalate copolymer, butylene glycol / adipic acid terephthalate copolymer, ethylene glycol / sebacic acid terephthalate copolymer, trimethylene glycol / sebacic acid terephthalate copolymer, butylene glycol / sebacic acid terephthalate copolymer, ethylene glycol / isophthalic acid / adipic acid terephthalate copolymer, trimethylene glycol / isophthalic acid / adipic acid terephthalate copolymer, butylene glycol / isophthalic acid / succinic acid terephthalate copolymer, ethylene glycol / isophthalic acid / adipic acid terephthalate copolymer, ethylene glycol / isophthalic acid / sebacic acid terephthalate copolymer, bisphenol A / terephthalic acid polymer, bisphenol A / isophthalic acid polymer, bisphenol A / terephthalic acid / isophthalic acid copolymer, etc.

[0027] In addition, as the above polyester resin, a liquid crystal polyester resin can also be cited. As the liquid crystal polyester resin, the following can be cited: p-hydroxybenzoic acid / ethylene glycol / terephthalic acid copolymer, hydroxynaphthoic acid / p-hydroxybenzoic acid copolymer, biphenol / benzoic acid / p-hydroxybenzoic acid copolymer, etc.

[0028] Among them, as the above-mentioned polyester resin, an aromatic polyester resin other than a liquid crystal polyester resin is preferred. Among the aromatic polyester resins other than the liquid crystal polyester resin, a polymer having an aromatic dicarboxylic acid and an alkylene glycol as structural units is preferred, and a polymer having an aromatic dicarboxylic acid and an alkylene glycol having 2 to 8 carbon atoms as structural units is more preferred, and a polymer having terephthalic acid and an alkylene glycol having 2 to 8 carbon atoms as structural units is further preferred. In addition, from the viewpoints of heat resistance and moldability, at least one selected from polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) is preferred, and polybutylene terephthalate (PBT) is particularly preferred.

[0029] The intrinsic viscosity of the polyester resin is preferably 0.5 to 1.8 dl / g, more preferably 0.6 to 1.5 dl / g. By setting the intrinsic viscosity of the polyester resin to a value equal to or higher than a specified value, durability can be improved, and by setting the intrinsic viscosity of the polyester resin to a value equal to or lower than a specified value, processability such as injection molding can be improved.

[0030] As the polyester elastomer, a polyester elastomer in which a hard segment composed of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as structural units is combined with at least one soft segment selected from an aliphatic polyether, an aliphatic polyester, and an aliphatic polycarbonate is preferred.

[0031] As the aromatic dicarboxylic acid constituting the polyester hard segment, the aromatic dicarboxylic acid units exemplified in the above-mentioned aromatic polyester resin can be cited, and the preferred modes are the same. In addition, similarly to the above-mentioned aromatic polyester resin, a dicarboxylic acid other than the aromatic dicarboxylic acid can also be contained as a structural unit, and the preferred modes are the same.

[0032] In addition, as the aliphatic diol and alicyclic diol constituting the polyester hard segment, the aliphatic diol and alicyclic diol exemplified in the above-mentioned aromatic polyester resin can be cited, and the preferred modes are the same.

[0033] As the above-mentioned hard segment, a polyester having an aromatic dicarboxylic acid and an alkylene glycol having 2 to 8 carbon atoms as structural units is preferred, and a polyester having terephthalic acid and an alkylene glycol having 2 to 8 carbon atoms as structural units is more preferred. In addition, from the viewpoints of heat resistance and moldability, at least one selected from polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) is preferred, and polybutylene terephthalate (PBT) is particularly preferred.

[0034] When an aromatic polyester suitable as the polyester constituting the hard segment is previously produced and then copolymerized with the soft segment component, the aromatic polyester can be easily obtained according to the usual polyester production method. In addition, it is desirable that the polyester has a number average molecular weight of 10,000 to 40,000.

[0035] Examples of the aliphatic polyether that constitutes the soft segment of the above polyester elastomer include polyether having one or more alkylene diols having 2 to 10 carbon atoms as structural units, such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polytrimethylene glycol, copolymer of ethylene oxide and propylene oxide, ethylene oxide adduct of polyethylene glycol, copolymer of ethylene oxide and tetrahydrofuran. The number average molecular weight of the aliphatic polyether is, for example, 300 to 5000, preferably 500 to 4000, and more preferably 700 to 2500.

[0036] Examples of the aliphatic polyester that constitutes the soft segment include aliphatic polyesters in which ester groups and alkylene groups having 2 to 12 carbon atoms are repeatedly arranged, such as poly(ε-caprolactone), polyheptalactone, polyoctalactone, and polybutylene adipate. The number average molecular weight of the aliphatic polyester is, for example, 300 to 5000, preferably 500 to 4000, and more preferably 700 to 2000.

[0037] Examples of the aliphatic polycarbonate that constitutes the soft segment include resins composed of carbonate units and aliphatic diol units. As the aliphatic diol, aliphatic diols having 2 to 12 carbon atoms are preferred. Examples of these aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, etc. In particular, from the viewpoints of the softness and low-temperature characteristics of the obtained polyester elastomer, aliphatic diols having 5 to 12 carbon atoms are preferred. These components can be used alone or in combination of two or more as needed. The number average molecular weight of the aliphatic polycarbonate is, for example, 300 to 15000, preferably 500 to 13000.

[0038] In the polyester elastomer, the composition ratio of the hard segment to the soft segment (hard segment / soft segment) is preferably 40 / 60 to 95 / 5, more preferably 50 / 50 to 95 / 5, and further preferably 55 / 45 to 90 / 10 on a mass basis.

[0039] The reduced viscosity of the polyester elastomer is preferably 0.5 dl / g or more and 3.5 dl / g or less, more preferably 1.0 dl / g or more and 3.0 dl / g or less, and further preferably 1.1 dl / g or more and 2.8 dl / g or less. By setting the reduced viscosity of the polyester elastomer above the specified value, the durability can be improved; by setting the reduced viscosity of the polyester elastomer below the specified value, the processability such as injection molding can be improved.

[0040] The acid value of the polyester elastomer is preferably 5 to 200 eq / ton, more preferably 10 to 80 eq / ton.

[0041] The Shore D hardness of the polyester elastomer is preferably 25 to 75, more preferably 25 to 65.

[0042] As the polycarbonate resin, there is no particular limitation as long as it is a resin composed of carbonate units and glycol units. For example, there can be mentioned: aromatic polycarbonate resins having carbonate units and aromatic glycol units as structural units, aliphatic polycarbonate resins having carbonate units and aliphatic glycol units as structural units, aromatic-aliphatic polycarbonate resins having carbonate units, aromatic glycol units and aliphatic glycol units as structural units, etc.

[0043] As the above-mentioned aromatic glycol constituting the polycarbonate resin, the same compounds as those described for the aromatic glycol as the structural unit of the polyester resin can be mentioned. As the above-mentioned aliphatic glycol constituting the polycarbonate resin, the same compounds as those described for the aliphatic glycol as the structural unit of the aliphatic polycarbonate which is the soft segment of the polyester elastomer can be mentioned.

[0044] The above-mentioned polyamide resin is a resin prepared using any one of amino acids, lactams, diamines and dicarboxylic acids as the main raw material. The polyamide resin can be prepared by polycondensing amino acids, ring-opening polymerizing lactams or polycondensing diamines and dicarboxylic acids. Among the raw materials constituting the polyamide resin, the amounts of amino acids, lactams, diamines and dicarboxylic acids are preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably 85 mol% or more.

[0045] As the above-mentioned amino acids, there can be mentioned: amino fatty carboxylic acids having about 4 to 15 carbon atoms such as 6-aminohexanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid; amino aromatic carboxylic acids such as p-aminomethylbenzoic acid, etc.

[0046] As the above-mentioned lactams, there can be mentioned: aliphatic lactams having about 5 to 15 carbon atoms such as ε-caprolactam, ω-dodecanolactam, etc.

[0047] Examples of the diamine include tetramethylene diamine, hexamethylene diamine, nonanediamine, sebacic diamine, undecanediamine, dodecamethylene diamine, 2,2,4- / 2,4,4-trimethylhexamethylene diamine, 5-methylnonanediamine, 2,4-dimethyloctanediamine, m-xylylenediamine, p-xylylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 3,8-bis(aminomethyl)tricyclodecane, bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(3-aminopropyl)piperazine, and the like. Examples of the dicarboxylic acid include adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 2-methylisophthalic acid, sodium isophthalate-5-sulfonate, hexahydroterephthalic acid, hexahydroisophthalic acid, diglycolic acid, and the like.

[0048] Specific examples of the polyamide resin include polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide 610, polyamide 69, polyamide 6T, polyamide 9T, polyamide MXD6, polyamide 6 / 66 copolymer, polyamide 6 / 610 copolymer, polyamide 6 / 6T copolymer, polyamide 6 / 66 / 610 copolymer, polyamide 6 / 12 copolymer, polyamide 6T / 12 copolymer, polyamide 6T / 66 copolymer, polyamide 6 / 6I copolymer, polyamide 66 / 6I / 6 copolymer, polyamide 6T / 6I copolymer, polyamide 6T / 6I / 66 copolymer, polyamide 6 / 66 / 610 / 12 copolymer, polyamide 6T / M-5T copolymer, and the like. Among them, from the viewpoint of good balance among chemical resistance, impact resistance, and fluidity of the obtained molded article, at least one selected from polyamide 6, polyamide 66, polyamide 12, and copolymers mainly composed of these is preferred, and at least one selected from polyamide 6 and copolymers mainly composed of polyamide 6 is more preferred. In addition, in this specification, "copolymer mainly composed of A" means a copolymer having a structure derived from A of preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably 85 mol% or more.

[0049] The relative viscosity of the polyamide resin measured in a 98% sulfuric acid solution (polyamide resin concentration: 1 g / dl, temperature: 20 °C) is preferably 1.5 to 3.5, more preferably 2.0 to 3.0, and further preferably 2.2 to 2.8.

[0050] The polyphenylene sulfide resin is not particularly limited, and commonly available polyphenylene sulfide resins can be used. Specifically, examples include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, polyphenylene sulfide ether, etc.

[0051] As the polyolefin resin, specifically, examples include homopolymers or copolymers having repeating units formed from α-olefins such as ethylene and propylene as the main component. For example, examples include propylene homopolymer, ethylene homopolymer, and further block or random copolymers obtained by copolymerizing ethylene with other α-olefins (such as propylene, 1-butene, etc.). These can be used singly or in two or more kinds within the range that imparts characteristics to the resin material. The polyolefin resin used in the present invention can also be either linear or branched. As the above polyolefin resin, at least one selected from polyethylene-based resins having ethylene-based structural units as the main component and polypropylene-based resins having propylene-based structural units as the main component is preferred. As the above polypropylene-based resin, any one of isotactic, atactic, syndiotactic, etc. polypropylene-based resins can be used. In addition, as the above polyethylene-based resin, examples include linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), ultra-low density polyethylene (ULDPE), ultra-high molecular weight polyethylene (UHMW-PE), etc.

[0052] The melting point of the component (A) is, for example, 100 to 350 °C, preferably 130 to 300 °C, more preferably 150 to 250 °C, and particularly preferably 160 to 240 °C.

[0053] The water content of the component (A) is, for example, 200 ppm or less, preferably 170 ppm or less, and more preferably 150 ppm or less. In addition, the water content of the component (A) can be adjusted to the above range by heating and drying the component (A), etc.

[0054] [Component (B)] In the electromagnetic wave absorbing composition of the present invention, Fe-Cr-Si-based soft magnetic metal powder is mixed as the component (B). The above Fe-Cr-Si-based soft magnetic metal powder is a soft magnetic metal powder containing Fe, Si, and Cr, and examples include Fe-Cr-Si-based stainless steel powder obtained by adding Si to stainless steels such as SUS410, SUS430, and SUS434, and Fe-Cr-Si-based soft magnetic metal powder having a Cr content of less than 10 mass% such as Fe-2Cr-8Si. Among them, from the viewpoints of oxidation resistance, availability, and cost, Fe-Cr-Si-based stainless steel powder is preferred, and Fe-Cr-Si-based ferritic stainless steel is more preferred. These Fe-Cr-Si-based soft magnetic metal powders can be used alone or in combination of two or more kinds.

[0055] The Cr contained in the Fe-Cr-Si-based soft magnetic metal powder as the component (B) helps to improve the corrosion resistance, resistance, and enhance the electromagnetic wave absorption energy. The Cr content in the Fe-Cr-Si-based soft magnetic metal powder is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, and further preferably 4.0% by mass or more. On the other hand, when the Cr content is excessive, there is a case where the saturation magnetization decreases, the imaginary part of the complex relative permeability decreases, and the electromagnetic wave absorption energy decreases. Therefore, the Cr content is preferably 21.0% by mass or less. Si helps to increase the resistance of the Fe-Cr-Si-based soft magnetic metal powder and enhance the electromagnetic wave absorption energy. When the Si content in the Fe-Cr-Si-based soft magnetic metal powder is too low, there is a case where the resistance of the Fe-Cr-Si-based soft magnetic metal powder becomes low and the electromagnetic wave absorption energy also becomes low. Therefore, the lower limit of the Si content is preferably 0.5% by mass. In addition, when the Si amount is excessive, there is a case where, similarly to Cr, the saturation magnetization decreases, the imaginary part of the complex relative permeability decreases, and the electromagnetic wave absorption energy decreases. Therefore, the upper limit of the Si content is preferably 10% by mass. The Fe-Cr-Si-based soft magnetic metal powder may also contain Mo. By containing Mo, the corrosion resistance and resistance of the soft magnetic metal powder can be improved. Since the corrosion resistance of the injection molded product obtained thereby can be improved and the resistance is further increased, the imaginary part of the complex relative permeability further increases, and the electromagnetic wave absorption energy can be further enhanced. From the above viewpoints, the Mo content in the Fe-Cr-Si-based soft magnetic metal powder is preferably 0 to 3.0% by mass. When manufacturing the soft magnetic metal powder, since waste materials etc. are used as raw materials, there is a possibility of mixing in impurities. The content of impurities in the Fe-Cr-Si-based soft magnetic metal powder is preferably 2.0% by mass or less. By controlling the content of impurities within the above range, a decrease in the electromagnetic wave absorption energy can be suppressed. In addition, impurities refer to elements other than Fe, Cr, Si, and Mo, and examples thereof include C, N, O, Cu, etc. as impurities.

[0056] The average particle size D50 of the Fe-Cr-Si-based soft magnetic metal powder as the component (B) is, for example, 1 to 50 μm, preferably 1 to 15 μm, more preferably 1 to 12 μm, and further preferably 1 to 10 μm. In addition, the average particle size D50 in the present invention represents the particle size at which the cumulative volume basis of the particle size is 50%. By adjusting the average particle size D50 of the component (B) to the above range, particularly, the electromagnetic wave absorption performance at high frequencies becomes better.

[0057] In the electromagnetic wave absorbing composition of the present invention, the mass ratio of component (A) to component (B) ((A) component / (B) component) is 5 / 95 to 80 / 20, preferably 20 / 80 to 80 / 20, more preferably 25 / 75 to 75 / 25. By containing component (A) and component (B) in such a mass ratio, the electromagnetic wave absorption performance can be improved. In addition, in the electromagnetic wave absorbing composition of the present invention, the addition amount (addition ratio) of the raw material components directly becomes the content (content ratio) in the electromagnetic wave absorbing composition and the content (content ratio) in the molded product.

[0058] [(C) component] In the electromagnetic wave absorbing composition of the present invention, in addition to the above-mentioned component (A) and component (B), it further contains at least one selected from phosphite compounds and phosphate compounds as component (C). Thereby, it is possible to suppress the increase in fluidity during heating while maintaining the electromagnetic wave absorption performance. As the above-mentioned component (C), as long as it is a phosphite compound and / or a phosphate compound, it can be used without particular limitation.

[0059] As the phosphite compound (also referred to as a phosphite ester compound), it is a compound containing one or more phosphorus atoms having three bonds, each phosphorus atom being bonded to s -OH groups, t -OR a groups and u -O-R b - groups (in the -O-R b - group, the phosphorus atom is bonded to -O-. R b is bonded to another phosphorus atom through another -O-). Among them, s + t + u = 3, t is 1 or more, when the number of phosphorus atoms in one molecule of the phosphite compound is 1, u is 0; when the number of phosphorus atoms is 2 or more, u is 1 or 2. When there are 2 or more phosphorus atoms, s, t, and u may be different depending on the phosphorus atoms, but are preferably the same. s is preferably 0. In addition, the number of phosphorus atoms in one molecule of the phosphite compound is preferably 1 to 4, more preferably 1 or 2, and particularly preferably 2. As R a , groups similar to the following R 1 ~R 3 can be cited. When the phosphite compound contains a plurality of R a , these may be different from each other, but are preferably the same. As R b , for example, a hydrocarbon group having a valence of 2 to 6, preferably 2 to 4, and a carbon number of 1 to 20 can be cited. The bonds of R b are all bonded to the phosphorus atom through -O-. As the hydrocarbon group represented by R b , the following can be cited: an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a combined group of an aliphatic hydrocarbon group and an aromatic hydrocarbon group, a combined group of two or more aromatic hydrocarbon groups, etc.

[0060] As a phosphite compound (also referred to as a phosphite ester compound), the compound in which s is 0 (a complete ester type compound) is preferred, and in particular, at least one selected from the compounds represented by the following formulas (C1-1) to (C1-3) is more preferred.

[0061] [Chemical formula 1] [In the formula, R 1 ~R 3 each independently represents an aliphatic hydrocarbon group having 1 to 30 carbon atoms or an aromatic hydrocarbon group having 6 to 30 carbon atoms.]

[0062] In formula (C1-1), the plurality of R 1 may be the same or different, preferably the same; in formula (C1-2), the plurality of R 2 may be the same or different, preferably the same; in formula (C1-3), the plurality of R 3 may be the same or different, preferably the same.

[0063] R 1 ~R 3 The aliphatic hydrocarbon group represented preferably has 2 to 25 carbon atoms, more preferably 8 to 23 carbon atoms, and still more preferably 12 to 20 carbon atoms.

[0064] R 1 ~R 3 The aliphatic hydrocarbon group represented may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group, preferably a saturated aliphatic hydrocarbon group. In addition, R 1 ~R 3 The aliphatic hydrocarbon group represented may be linear or branched, preferably linear. Examples of the above aliphatic hydrocarbon group include: saturated aliphatic hydrocarbon groups such as methyl, ethyl, n-propyl, n-butyl, 2-ethylhexyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, and n-eicosyl; unsaturated aliphatic hydrocarbon groups such as vinyl, propenyl, butenyl, dodecenyl, tetradecenyl, hexadecenyl, octadecenyl, and eicosenyl.

[0065] R 1 ~R 3 The aromatic hydrocarbon group represented preferably has 6 to 25 carbon atoms, more preferably 7 to 23 carbon atoms, and still more preferably 10 to 20 carbon atoms.

[0066] As R 1 ~R 3Examples of the aromatic hydrocarbon group represented include aryl groups such as phenyl and naphthyl; alkylaryl groups in which 1 to 5 alkyl groups having 1 to 4 carbon atoms are bonded to the aryl group, etc. Among them, a group in which 1 to 5 alkyl groups having 1 to 4 carbon atoms are bonded to the phenyl group is preferred, and a group in which 1 to 3 tert-butyl groups are bonded to the phenyl group is more preferred. The bonding position of the alkyl group having 1 to 4 carbon atoms (preferably tert-butyl) bonded to the above phenyl group is not particularly limited, and it is preferably bonded to any of the 2-position, 2,4-positions, 2,6-positions, and 2,4,6-positions where the phenyl group is bonded to -O-P.

[0067] Specific examples of the phosphite compound include: bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, and tetra(2,4-di-tert-butylphenyl)-4,4'-biphenyldiphosphite, etc.

[0068] Examples of the phosphate compound (also referred to as a phosphate compound) include: a compound containing P=O having 3 bonds on 1 or more phosphorus atoms, and the phosphorus atom of each P=O is bonded to s -OH groups, t -OR a groups, u -O-R b - groups (-O-R b - groups, in which the phosphorus atom of P=O is bonded to -O-. R b is bonded to the phosphorus atom of other P=O through another -O-). Among them, s + t + u = 3, t is 1 or more, when there is 1 P=O, u is 0; when there are 2 or more P=Os, u is 1 or 2. When there are 2 or more P=Os, s, t, and u may be different according to different P=Os, and are preferably the same. s is preferably 1 or 2. R a and R b are the same as above. Among them, the number of P=Os in 1 molecule of the phosphate compound is preferably 1 or 2, and more preferably 1.

[0069] As the phosphate compound, a compound represented by the following formula (C2) is preferred.

[0070] [Chemical formula 2] [In formula (C2), s1 represents an integer from 0 to 2, t1 represents an integer from 1 to 3, and R a is the same as above. Among them, s1 + t1 = 3.]

[0071] When formula (C2) has multiple Rs a , these may be the same or different, and are preferably the same.

[0072] Preferably, s1 is 1 or 2.

[0073] As the compound represented by formula (C2), it may be R a A compound in which all are aromatic hydrocarbon groups having 6 to 30 carbon atoms (hereinafter sometimes referred to as an aromatic phosphate compound), or it may be R a A compound in which all are aliphatic hydrocarbon groups having 1 to 30 carbon atoms (hereinafter sometimes referred to as an aliphatic phosphate compound). An aliphatic phosphate compound is preferred, and among them, a compound in which s1 is 1 or 2 (acid type compound) is more preferred, and a compound represented by the following formula (C2-1) is further preferred.

[0074] [Chemical formula 3] [In formula (C2-1), R 4 Is an aliphatic hydrocarbon group having 1 to 30 carbon atoms, and n is 1 or 2.]

[0075] In formula (C2-1), when there are a plurality of R 4 , the plurality of R 4 May be the same or different, and are preferably the same.

[0076] R 4 The aliphatic hydrocarbon group represented preferably has 1 to 25 carbon atoms, more preferably 2 to 23 carbon atoms, and further preferably 2 to 20 carbon atoms. In particular, by using a phosphate compound in which R 4 Is an aliphatic hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms), the effect of suppressing the increase in fluidity during heating is more excellent. In addition, the above carbon atom number may be 8 to 23 or 12 to 20. In formula (C2-1), the content of the phosphate compound in which R 4 Is an aliphatic hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms) is preferably 20% by mass or more, more preferably 40% by mass or more, further preferably 50% by mass or more, particularly preferably 80% by mass or more, and may also be 100% by mass in the total 100% by mass of component (C).

[0077] As the aliphatic hydrocarbon group represented by R 4 , groups similar to the groups described as the aliphatic hydrocarbon groups represented by R 1 To R 3 Can be mentioned. Among them, a linear aliphatic hydrocarbon group is preferred, and a linear saturated aliphatic hydrocarbon group is more preferred.

[0078] n can be 1, can be 2, or a mixture of a compound in which n is 1 and a compound in which n is 2 can also be used.

[0079] As phosphate ester compounds, specifically, the following can be cited: mono- or dimethyl phosphate, mono- or diethyl phosphate, mono- or dibutyl phosphate, mono- or bis(2-ethylhexyl) phosphate, mono- or dilauryl phosphate, mono- or distearyl phosphate, mono- or dioleyl phosphate, etc. These phosphate ester compounds can be used alone or in combination of two or more. As the phosphate ester compound, at least one selected from monoethyl phosphate, diethyl phosphate, monostearyl phosphate, and distearyl phosphate is preferred.

[0080] As the phosphate ester compound, commercially available products can be used, and examples include: LBT-1830, LBT-1813 manufactured by Sakai Chemical Industry Co., Ltd., JP-502 manufactured by Johoku Chemical Industry Co., Ltd., ADK STAB AX-71 manufactured by ADEKA Corporation, etc.

[0081] As the component (C), one kind can be used alone, or two or more kinds can be used in combination.

[0082] As the component (C), at least one selected from phosphate ester compounds is preferred.

[0083] Relative to 100 parts by mass in total of the components (A) and (B), the content of the component (C) in the present invention is 0.02 to 1.4 parts by mass, preferably 0.03 to 1.2 parts by mass, more preferably 0.03 to 1.0 parts by mass, and further preferably 0.1 to 1.0 parts by mass. The component (C) is considered to form a surface coating film of the component (B). Regarding the detailed mechanism, it is not yet clear, but it is considered that the component (C) is liable to coordinate on the surface of the component (B) due to having structures such as P-OH, P-OR a 、P-O-R b -, P=O, and tends to easily form the above-mentioned surface coating film. Then, it is considered that by forming such a surface coating film, the effects of improving the dispersibility of the component (B) and suppressing the deterioration behavior of the resin or elastomer caused by the component (B) can be observed. When the above content is less than 0.02 parts by mass, it is difficult to obtain the desired properties. On the contrary, when it is more than 1.4 parts by mass, since the component (C) acts as a plasticizer, the fluidity during heating deteriorates, so it is not preferred.

[0084] In addition, relative to 100 parts by mass of the component (B), the content of the component (C) is, for example, 0.05 to 2.0 parts by mass, preferably 0.1 to 1.5 parts by mass, more preferably 0.3 to 1.2 parts by mass, and further preferably 0.4 to 1.0 parts by mass.

[0085] The total content ratio of the components (A), (B), and (C) in the electromagnetic wave absorbing composition is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 98% by mass or more, and can be 100% by mass or 99.5% by mass or less.

[0086] [Other components] According to its purpose, the electromagnetic wave absorbing composition of the present invention may further contain various additives such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, dyes, pigments, lubricants, plasticizers, mold release agents, crystal growth promoters, crystal nucleating agents, and epoxy compounds. When the total of the above components (A) and (B) is 100 parts by mass, the total amount of these various additives is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 2 parts by mass or less.

[0087] As the above antioxidant, a hindered phenol antioxidant is preferred, and specifically, 3,5-di-tert-butyl-4-hydroxytoluene, n-octadecyl-β-(4'-hydroxy-3',5'-di-tert-butylphenyl) propionate, tetra [methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl) benzene, calcium (3,5-di-tert-butyl-4-hydroxybenzyl monoethyl phosphate), triethylene glycol bis [3-(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 3,9-bis{1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl}-2,4,8,10-tetraoxaspiro [5.5] undecane, bis [3,3-bis(4'-hydroxy-3'-tert-butylphenyl) butyric acid] glycol ester, 2,2'-ethylidenebis(4,6-di-tert-butylphenol), N,N'-bis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, 2,2'-oxamide bis [ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, triester of 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid and 1,3,5-tris(2-hydroxyethyl)-S-triazine-2,4,6(1H,3H,5H) trione, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxybenzamide), etc. These antioxidants can be used alone or as a mixture. When the total of the above components (A) and (B) is 100 parts by mass, the amount of the antioxidant is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and still more preferably 1 part by mass or less.

[0088] Examples of the above mold release agents include long-chain fatty acids or their esters, metal salts, amide compounds, polyethylene wax, silicon, polyethylene oxide, etc. As the long-chain fatty acid, those having 12 or more carbon atoms are particularly preferred, and examples thereof include stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, etc. Part or all of the carboxylic acids may be esterified with monoglycol or polyglycol, or may form a metal salt. Examples of the amide compound include ethylene bis-p-phthalamide, methylene bis-stearamide, etc. These mold release agents can be used alone or as a mixture. When the total of the above components (A) and (B) is 100 parts by mass, the amount of the mold release agent is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and still more preferably 1 part by mass or less.

[0089] The electromagnetic wave absorbing composition of the present invention usually does not contain components other than the above (such as fiber components such as thermosetting resins and glass fibers), but may contain them according to need. For example, in the electromagnetic wave absorbing composition of the present invention, the thermosetting resin can be set to 0.2% by mass or less, and in the electromagnetic wave absorbing composition of the present invention, the fiber component can be set to 4% by mass or less.

[0090] The method for producing the electromagnetic wave absorbing composition of the present invention is not particularly limited. For example, after dry-mixing the components (A), (B), and (C) and other components used as needed, it can be melt-kneaded using a single-screw or twin-screw extrusion melt-kneader or a general mixer for thermoplastic resins typified by a kneading-type heating machine. Thereafter, if necessary, granulation can also be carried out through a granulation process. In addition, if necessary, the component (B) can be pretreated (mixed) with the component (C) in advance and then mixed with the component (A).

[0091] Since the electromagnetic wave absorbing composition of the present invention can suppress the decrease in fluidity during heating, its mass productivity is excellent. When measured according to ISO1133, the ΔMFR of the electromagnetic wave absorbing composition of the present invention calculated by the following formula is preferably 50 g / 10 min or less, more preferably 40 g / 10 min or less, still more preferably 30 g / 10 min or less, 20 g / 10 min or less, or 10 g / 10 min or less. The lower limit of the ΔMFR of the electromagnetic wave absorbing composition of the present invention is not particularly limited and can be 1 g / 10 min or more. ΔMFR = (MFR at 20 minutes of residence) - (MFR at 5 minutes of residence) (In the formula, the MFR at 20 minutes of residence refers to the melt flow rate measured with a preheating time of 20 minutes, and the MFR at 5 minutes of residence refers to the melt flow rate measured with a preheating time of 5 minutes. In addition, the load during the measurement of the melt flow rate is set to 2160 g, and the measurement temperature is set to the melting point of the component (A) + 25 °C.) In addition, when the electromagnetic wave absorbing composition contains two or more (A) components having different melting points, the measurement temperature may be the melting point of the (A) component having the highest melting point + 25°C.

[0092] When forming a molded article from the electromagnetic wave absorbing composition of the present invention, the forming method of the electromagnetic wave absorbing composition is not particularly limited, and injection molding, extrusion molding, compression molding, blow molding, etc. can be performed. From the viewpoint of the degree of freedom of the shape of the obtained molded article, injection molding is preferred. In addition, the excellent effect of suppressing the increase in fluidity during heating of the electromagnetic wave absorbing composition of the present invention is easily exerted during injection molding, so it is preferably used for injection molding.

[0093] The molded article produced from the composition of the present invention is characterized by containing the above-mentioned (A) component and the above-mentioned (B) component in a mass ratio ((A) component / (B) component) in the range of 5 / 95 to 80 / 20, and further containing the above-mentioned (C) component in an amount of 0.02 to 1.4 parts by mass based on 100 parts by mass in total of the above-mentioned (A) component and the above-mentioned (B) component, and the electromagnetic wave absorption energy P represented by the following formula (1) is 5 kW / m at 79 GHz. 3 or more. In addition, the molded article may also contain various additives described above as other components. The preferred modes of the types and amounts of the components contained in the molded article are the same as those described above. As described above, the electromagnetic wave absorbing composition of the present invention is preferably used for injection molding, that is, the molded article produced from the electromagnetic wave absorbing composition of the present invention preferably has gate marks. In addition, "gate marks" refer to marks such as unevenness formed due to the gate used for injecting the composition when manufacturing a molded article by injection molding.

[0094] The shape of the molded article is not particularly limited, and it can form a shape (flat plate shape, housing, etc.), thickness, and size suitable for the application. As the thickness of the molded article, for example, it is 0.1 to 10 mm, and preferably 0.3 to 5 mm.

[0095] Regarding the absorption of electromagnetic waves by a substance, the electromagnetic wave absorption energy P is represented by the following formula (1).

[0096] [Equation 2] [In formula (1), P represents the electromagnetic wave absorption energy (W / m 3 ), μ 0 represents the vacuum permeability (H / m), μ r " represents the loss term of the complex relative permeability, ε 0 represents the vacuum permittivity (F / m), ε r" represents the loss term of the complex relative permittivity, ρ represents the resistivity (Ωm), H represents the magnetic field strength (A / m), E represents the electric field strength (V / m), and f represents the frequency (Hz).

[0097] On the right side of Equation (1), the first term represents magnetic loss, the second term represents dielectric loss, and the third term represents resistive loss.

[0098] Here, the complex relative permeability μ r and the complex relative permittivity ε r can be obtained as follows. That is, by the Nicolson Ross Weir method (refer to IEC TR 63307), the S-parameters of the sample are measured using Network Analyzers, and the complex relative permeability (μ r = μ r '- jμ r ") and the complex relative permittivity (ε r = ε r '- jε r ") can be obtained from the measured S-parameters using the Nicolson Ross Weir formula. By substituting the values thus obtained into Equation (1), the electromagnetic wave absorption energy P can be calculated.

[0099] In addition, the complex magnetic permeability μ [H / m] and the complex permittivity ε [F / m] are expressed as follows.

[0100] [Equation 3] μ = μ 0 μ r = μ' - jμ" = μ 0 (μ r ' - jμ r ") (4-1)

[0101] [Equation 4] ε = ε 0 ε r = ε' - jε" = ε 0 (ε r ' - jε r ") (4-2) At this time, μ' and μ" are the real part and the imaginary part (loss term) of the complex magnetic permeability, μ r ' and μ r " are the real part and the imaginary part (loss term) of the complex relative magnetic permeability, ε' and ε" are the real part and the imaginary part (loss term) of the complex permittivity, and ε r ' and ε r " are the real part and the imaginary part (loss term) of the complex relative permittivity. In addition, j is the imaginary unit.

[0102] The electromagnetic wave absorbing composition of the present invention has excellent electromagnetic wave absorption performance. Therefore, the electromagnetic wave absorption energy P calculated according to the above formula (1) at 79 GHz can be 5 kW / m 3 or more. The above electromagnetic wave absorption energy P is preferably 15 kW / m 3 or more, more preferably 25 kW / m 3 or more, and still more preferably 30 kW / m 3 or more. The upper limit of the above electromagnetic wave absorption energy P is not particularly limited, for example, it is 100 kW / m 3 or less. In addition, for the electromagnetic wave absorption energy P of the electromagnetic wave absorbing composition, it can be measured using a test piece with a thickness of 1 mm made of a molded (preferably injection molded) electromagnetic wave absorbing composition.

[0103] In addition, the above electromagnetic wave absorption energy P and ΔMFR can be measured according to the methods shown in the following examples.

[0104] This application claims the benefit of priority based on Japanese Patent Application No. 2022-178676 filed on November 8, 2022. The entire contents of the specification of Japanese Patent Application No. 2022-178676 filed on November 8, 2022 are incorporated herein by reference. Examples

[0105] Examples are given below to further illustrate the present invention in detail. The present invention is not limited by these examples.

[0106] <Examples 1 to 13 and Comparative Examples 1 to 6> In Examples 1 to 13 and Comparative Examples 1 to 6, the following materials were used as components of the electromagnetic wave absorbing composition.

[0107] [Component (A)] A-1: Polybutylene terephthalate, melting point 225 °C, resin drying temperature 130 °C (Manufactured by Toyobo Co., Ltd., intrinsic viscosity = 0.83 dl / g) A-2: Polybutylene terephthalate, melting point 225 °C, resin drying temperature 130 °C (Manufactured by Toyobo Co., Ltd., intrinsic viscosity = 1.32 dl / g) A-3: Polyester elastomer; melting point 205 °C; resin drying temperature 100 °C Copolymer with a composition ratio of PBT / HPCD = 70 / 30 (mass%) (Pelprene (registered trademark) manufactured by Toyobo Co., Ltd., specific viscosity: 1.20 dl / g, Shore D hardness: 60) The polyester elastomer (A-3) is manufactured according to the following method. At 225 °C to 245 °C and 130 Pa, 70 parts by mass of polybutylene terephthalate (PBT) with a number average molecular weight of 30,000 and 30 parts by mass of polycarbonate diol (HPCD) with a number average molecular weight of 10,000 having 1,6-hexanediol residues are stirred for 1 hour. The transesterification reaction is carried out, and when it is confirmed to become transparent, the content is taken out and cooled to obtain the polyester elastomer (A-3). A-4: Polyester elastomer, melting point 180 °C, resin drying temperature 100 °C Polyester elastomer with terephthalic acid (TPA) / / 1,4-butanediol (BD) / polyoxytetramethylene glycol (PTMG: number average molecular weight 2000) at 100 / / 75 / 25 (mol%) (inherent viscosity: 2.50 dl / g, acid value: 21 eq / ton, Shore D hardness: 31) A-5: Polyamide 6, melting point 225 °C, resin drying temperature 100 °C (Manufactured by Toyobo Co., Ltd., relative viscosity = 2.2)

[0108] In addition, the above melting point, intrinsic viscosity, reduced viscosity, Shore D hardness, acid value, and relative viscosity are measured according to the following methods.

[0109] <Melting point> In a differential scanning calorimeter "DSC220 type" manufactured by Nihon Seiko Electronics, 5 mg of the sample is placed in an aluminum pan, covered with a lid and sealed, and heated from 20 °C to 270 °C at 10 °C / min in nitrogen. Based on the obtained thermogram curve, the melting endothermic peak is taken as the melting point.

[0110] <Intrinsic viscosity> Dissolve 0.1 g of the sample in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4), and measure it at 30 °C using an Ubbelohde viscometer. (Unit: dl / g)

[0111] <Reduced viscosity> Dissolve 0.05 g of the sample in 25 ml of a mixed solvent (phenol / tetrachloroethane = 60 / 40 (mass ratio)), and measure it at 30 °C using an Ostwald viscometer. (Unit: dl / g)

[0112] <Shore D hardness> Measure according to JIS K7215-1986. For the test piece, three injection molded products (length 100 mm, width 100 mm, thickness 2 mm) made at a barrel temperature of 240 °C and a mold temperature of 50 °C are overlapped, and measured with a hardness tester using a D-type indenter under a pressure of 5000 g. The value 5 seconds after the start of measurement is taken as the D hardness (Shore D hardness).

[0113] <Acid value> Dissolve 0.5 g of the sample in 25 ml of benzyl alcohol and titrate with a 0.01 mol / l benzyl alcohol solution of sodium hydroxide. As the indicator, use a solution prepared by dissolving 0.10 g of phenolphthalein in a mixture of 50 mL of ethanol and 50 mL of water.

[0114] <Relative viscosity> Dissolve 0.25 g of the polyamide resin in 25 ml of 98% sulfuric acid. Put 10 ml of this sample solution into an Ostwald viscometer and measure it at 20 °C. In addition, put the solvent (98% sulfuric acid) into the Ostwald viscometer and measure it at 20 °C. Calculate the relative viscosity by the following formula. RV = T / T0 RV: Relative viscosity, T: Drop time of the sample solution, T0: Drop time of the solvent

[0115] 〔Component (B)〕 B-1: Fe-13Cr-1Si (Average particle size D50: about 10 μm) B-2: Fe-17Cr-2Si (Average particle size D50: about 10 μm) B-3: Fe-2Cr-8Si (Average particle size D50: about 10 μm) For the above average particle size D50, it can be obtained by putting ethanol and the sample powder into a beaker, dispersing them with an ultrasonic cleaner for 30 seconds, putting them into the chamber of the sample circulator of a laser diffraction / scattering particle size distribution analyzer MT3300EXII (manufactured by MicrotracBEL Co., Ltd.), and measuring the volume distribution with a measurement time of 120 seconds. The particle size at 50% of the measured volume distribution is taken as the average particle size D50.

[0116] 〔Component (C)〕 C-1: "JP-502" manufactured by Johoku Chemical Industry Co., Ltd. C-2: "ADK STAB AX-71" manufactured by ADEKA Corporation

[0117] 〔Other additives〕 Antioxidant: IRGANOX 1010 manufactured by BASF Corporation Release agent: LICOWAX-OP manufactured by Clariant Corporation

[0118] The components shown in Table 1 were dry-blended in the proportions (parts by mass) shown in Table 1, and using a twin-screw extruder (STS-35 manufactured by COPERION), the barrel temperature was set to the melting point of each (A) component + 25°C, and melt-kneaded under the conditions of a discharge rate of 20 kg / hr and a screw rotation speed of 180 rpm to produce electromagnetic wave absorbing composition pellets. Using the obtained pellets, ΔMFR was measured according to the method described below. In addition, test pieces were produced from the obtained pellets according to the method described below, and the electromagnetic wave absorption energy P of the electromagnetic wave absorbing composition at 79 GHz was measured. The measurement results of the electromagnetic wave absorbing compositions of Examples 1 to 13 and Comparative Examples 1 to 6 were recorded in Table 1.

[0119] <Electromagnetic wave absorption energy P at 79 GHz> To calculate the electromagnetic wave absorption energy P, the production (molding) and measurement of test pieces were carried out in the following order. Using an injection molding machine manufactured by Toshiba Machine Co., Ltd., the barrel temperature was set to the melting point of each (A) component + 25°C and the mold temperature was set to 50°C, and injection molded into a flat plate having a shape of 100 mm × 100 mm × 1 mm (thickness), and then the test piece was processed into a size that could be inserted into a sample holder used in the following Nicolson Ross Weir method (refer to IECTR63307).

[0120] The electromagnetic wave absorption energy P was calculated from the following formula (1).

[0121] [Equation 5] [In formula (1), P represents the electromagnetic wave absorption energy (W / m 3 ), μ 0 represents the vacuum permeability (H / m), μ r ” represents the loss term of the complex relative permeability, ε 0 represents the vacuum permittivity (F / m), ε r ” represents the loss term of the complex relative permittivity, ρ represents the resistivity (Ωm), H represents the magnetic field strength (A / m), E represents the electric field strength (V / m), and f represents the frequency (Hz).]

[0122] For the measurement of each parameter, it is as described below. Prepare Network Analyzers N5227A (manufactured by Keysight Technologies), connect it to the millimeter-wave controller N5261A (manufactured by Keysight Technologies), insert test pieces (thickness 1 mm) from Examples 1 to 13 and Comparative Examples 1 to 6 on the sample holder, and measure the S parameters according to the Nicolson Ross Weir method (refer to IECTR63307). From the measured S parameters, substitute them into the Nicolson Ross Weir formula (refer to IECTR63307) to calculate the complex relative magnetic permeability (μ r = μ r ’ - jμ r ”) and the complex relative permittivity (ε r = ε r ’ - jε r ”). Additionally, in Equation (1), it is calculated as |H| = 1 [A / m], |E| = 1 [V / m], ρ = 1×10 7 [Ωm].

[0123] [Degree of increase in fluidity during heating (ΔMFR)] Based on the measurement results of the melt flow rate according to different preheating times, evaluate the degree of increase in fluidity when heating the electromagnetic wave absorbing composition. In the following evaluation, consider the preheating time as the heating time of the electromagnetic wave absorbing composition. Use a melt indexer (manufactured by Toyo Seiki Co., Ltd.) to measure the MFR at 20 minutes of residence and the MFR at 5 minutes of residence for pellets whose moisture content has been adjusted to 200 ppm or less by drying at a specific resin drying temperature set according to each (A) component for 3 hours, under the condition of a load of 2160 g in accordance with ISO1133. Additionally, set the test temperature to the melting point of the (A) component + 25 °C (250 °C for the polybutylene terephthalate resin of A-1 and A-2, 230 °C for the polyester elastomer resin of A-3, 205 °C for the polyester elastomer resin of A-4, 250 °C for the polyamide resin of A-5). Substitute the obtained measurement results into the following formula to obtain ΔMFR. ΔMFR = (MFR at 20 minutes of residence) - (MFR at 5 minutes of residence) (In the formula, the MFR at 20 minutes of residence refers to the melt flow rate measured with a preheating time of 20 minutes according to the method based on ISO1133, and the MFR at 5 minutes of residence refers to the melt flow rate measured with a preheating time of 5 minutes according to the method based on ISO1133.)

[0124] [Table 1]

[0125] As is clearly shown in Table 1, the results are that the electromagnetic wave absorbing compositions of Examples 1 to 13 of the present invention can suppress the increase in fluidity during heating while maintaining good electromagnetic wave absorption performance by mixing an Fe-Cr-Si-based soft magnetic metal powder as component (B) and at least one selected from phosphite-based compounds and phosphate-based compounds as component (C) in a specific range of proportions into a thermoplastic resin or a thermoplastic elastomer as component (A). On the other hand, in Comparative Examples 1 to 6 where component (C) was not used or the content of component (C) was outside the specific range, the increase in fluidity during heating was increased, and there was concern about the negative impact on mass productivity. Industrial applicability

[0126] According to the present invention, since it is possible to suppress the increase in fluidity during heating and obtain a resin- or elastomer-containing composition having excellent electromagnetic wave absorption performance, it is expected that components having electromagnetic wave noise as a problem can be manufactured with high production efficiency. In particular, in order to ensure the safety during vehicle driving, the number of millimeter-wave radars mounted is increased to have a high-speed and high-precision detection function under electromagnetic waves of 79 GHz, but malfunction due to noise is a major safety issue, and it is essential to take countermeasures. At this time, by applying the electromagnetic wave absorbing composition of the present invention, in addition to expecting weight reduction brought about by replacing metals and the like, an increase in the degree of freedom of shape can also be expected. Furthermore, by applying the electromagnetic wave absorbing composition of the present invention, it is possible to impart electromagnetic wave absorption performance to a housing material that usually does not have a noise countermeasure function, and thus it is possible to achieve componentization with higher safety, which can be called an epoch-making material.

Claims

1. An electromagnetic wave absorbing composition, characterized in that, it contains at least one selected from thermoplastic resins and thermoplastic elastomers as component (A) and Fe-Cr-Si series soft magnetic metal powder as component (B) in a mass ratio of component (A) / component (B) in the range of 5 / 95 to 80 / 20; furthermore, with respect to a total of 100 parts by mass of the component (A) and the component (B), it contains at least one selected from phosphite compounds and phosphate compounds in an amount of 0.02 to 1.4 parts by mass as component (C), The electromagnetic wave absorption energy P shown in Equation (1) is 5 kW / m at 79 GHz 3 Above 2. The electromagnetic wave absorbing composition according to claim 1, characterized in that, when measured according to ISO1133, the ΔMFR calculated by the following formula is 50 g / 10 min or less, ΔMFR = (MFR at 20 minutes of residence) - (MFR at 5 minutes of residence) In the formula, the MFR at 20 minutes of residence refers to the melt flow rate measured with a preheating time of 20 minutes, and the MFR at 5 minutes of residence refers to the melt flow rate measured with a preheating time of 5 minutes; wherein, the load during the melt flow rate measurement is 2160 g, and the measurement temperature is the melting point of component (A) + 25 °C.

3. The electromagnetic wave absorbing composition according to claim 1 or 2, characterized in that, the component (A) contains one or more selected from polyester resins, polyester elastomers, polycarbonate resins, polyamide resins, polyphenylene sulfide resins and polyolefin resins.

4. The electromagnetic wave absorbing composition according to claim 1 or 2, characterized in that, the component (B) contains 1.0 to 21.0% by mass of Cr, 0.5 to 10.0% by mass of Si, 0 to 3.0% by mass of Mo, and the balance is composed of Fe and impurities.

5. The electromagnetic wave absorbing composition according to claim 1 or 2, characterized in that, the average particle size D50 of the component (B) is 3 to 15 μm.

6. A molded article composed of the electromagnetic wave absorbing composition according to claim 1 or 2.

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