Crushed material, material, compact, and method for manufacturing compact

Abstract

To provide a crushed material of a resin composition containing a thermoplastic resin, a material, a molding, and a method for manufacturing a molding, which can maintain high electromagnetic wave absorption properties when being recycled.SOLUTION: A crushed material of a resin composition contains a thermoplastic resin and a carbon nanotube, wherein an absorption rate at a frequency of 76.5 GHz when the crushed material is molded into a thickness of 2 mm is 40.0-100%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a crushed material, a material, a molded body, and a method for manufacturing a molded body, and in particular to a crushed material made from recycled thermoplastic resins. [Background technology]

[0002] Thermoplastic resins have been conventionally molded into various molded articles. However, in recent years, there has been a strong demand for the reuse of resources, and the recycling of thermoplastic resins has also been studied (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-080428 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when a molded thermoplastic resin body is recycled and molded again, there is a problem that various physical properties are deteriorated compared to when virgin thermoplastic resin before recycling is used. Meanwhile, the present inventors have been conducting research and development into resin compositions containing thermoplastic resins that have high electromagnetic wave absorption properties. It is predicted that there will be a demand for recycling of such resin compositions with high electromagnetic wave absorption properties in the future. The present invention aims to solve such problems and to provide crushed materials, materials, molded articles, and a method for manufacturing molded articles of resin compositions containing thermoplastic resins that can maintain high electromagnetic wave absorption properties even when recycled. [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 using carbon nanotubes as the conductive material in a resin composition containing a thermoplastic resin and a conductive material for achieving electromagnetic wave absorption. Specifically, the above problems were solved by the following means. <1> A crushed material of a resin composition containing a thermoplastic resin and carbon nanotubes, which, when molded into a 2 mm thick molded body, has an absorption rate of 40.0 to 100% at a frequency of 76.5 GHz as calculated according to formula (A). Formula (A)

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[0006] The present invention makes it possible to provide crushed material, materials, molded articles, and methods for producing molded articles of resin compositions containing thermoplastic resins, which are capable of maintaining high electromagnetic wave absorption properties even after recycling. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the recycling flow of a resin composition (pellets) containing a thermoplastic resin and a conductive material. 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 "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. If the measurement methods, etc. described in the standards shown in this specification vary from year to year, they will be based on the standards as of January 1, 2021, unless otherwise stated.

[0009] The crushed material of this embodiment is crushed material of a resin composition containing a thermoplastic resin and carbon nanotubes, and is characterized in that when the crushed material (or a material containing the crushed material) is molded into a 2 mm thick molded body, the absorption rate calculated according to formula (A) at a frequency of 76.5 GHz is 40.0 to 100%. Formula (A)

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[0010] Like this crushed material can maintain high electromagnetic wave absorption even after recycling. Furthermore, can maintain low electromagnetic wave reflectance and electromagnetic wave absorption even after recycling. As described above, the present inventors have been investigating resin compositions that can provide molded articles with high electromagnetic wave absorption properties by blending a thermoplastic resin with a conductive material. Meanwhile, in recent years, there has been a demand for the recycling of thermoplastic resins in light of environmental impact. Therefore, the present inventors have investigated ways to make resin compositions that can provide molded articles with high electromagnetic wave absorption properties recyclable. Specifically, as shown in FIG. 1 , when a resin composition (pellets) 1 containing a thermoplastic resin and a conductive material is injection-molded using an injection molding machine 2, rejects 4 and scraps 5 are typically produced in addition to acceptable products 3. It is conceivable to crush such rejects 4 and scraps 5 using a crusher 6, and reuse the resulting crushed material 7 8 for injection molding again.

[0011] However, the inventors have conducted research and found that when a resin composition containing a thermoplastic resin and a conductive material is recycled as described above, the electromagnetic wave absorption properties of the resulting molded article may be reduced. The present inventors have surprisingly found that this problem can be solved by using carbon nanotubes as the conductive material, that is, by using carbon nanotubes, it is possible to maintain an extremely high level of electromagnetic wave absorption even when a resin composition containing a thermoplastic resin and a conductive material is recycled. The reason why carbon nanotubes, when used as a conductive material, can maintain high electromagnetic wave absorption properties even after recycling is believed to be as follows. First, when recycling a resin composition containing a thermoplastic resin and a conductive material, for example, as shown in Figure 1, rejected molded products 4 and scraps 5 formed from a resin composition 1 containing a thermoplastic resin and a conductive material are crushed by a crusher 6 to produce crushed material 7. It was assumed that ordinary conductive materials are cut or broken during molding or crushing, resulting in a decrease in electromagnetic wave absorption properties. In contrast, carbon nanotubes are thin and short, but each individual nanotube has high strength, so they tend to be less likely to cut or break during molding or crushing. Therefore, it was believed that excellent electromagnetic wave absorption properties can be maintained even if a resin composition containing a thermoplastic resin and carbon nanotubes is crushed and then remolded.

[0012] In this embodiment crushed material The present invention relates to a resin composition containing a thermoplastic resin and carbon nanotubes. crushed material Such a crushed material Even when recycled and molded into a molded article, the material has excellent electromagnetic wave absorption properties. crushed material of the resin composition crushed material As long as the resin composition is not particularly limited, it is possible to utilize, for example, recycled products of a resin composition containing a thermoplastic resin and carbon nanotubes. In particular, a molded product formed from a resin composition containing a thermoplastic resin and carbon nanotubes can be utilized as the resin composition. Examples of the molded product here include an injection molded product and an extrusion molded product. Furthermore, the molded product here may be a flat plate-shaped molded product such as a film, or a molded product formed using a mold. Specifically, examples of the molded product include rejected products and scraps that are generated when molding a resin composition.

[0013] As described above, the crushed material of this embodiment is a crushed material of a resin composition containing a thermoplastic resin and carbon nanotubes. crushed material By molding machine, crushing will be done. crushed material The size of is not particularly specified, but for example, crushed materialFor 50% by mass or more, further 70% by mass or more, and particularly 90% by mass or more, the longest portion is preferably 20.0 mm or less, more preferably 8.0 mm or less, and is preferably 1.0 mm or more, more preferably 2.0 mm or more.

[0014] In this embodiment, when the crushed material (preferably a material containing crushed material) is molded into a molded body having a thickness of 2 mm (preferably, a thickness of 100 mm × 100 mm × 2 mm), the absorption rate calculated according to formula (A) at a frequency of 76.5 GHz is 40.0 to 100%. crushed material uses carbon nanotubes as the conductive material, making it possible to achieve such a high electromagnetic wave absorption rate. In particular, 10 mass % or more, and further 20 mass % or more of the material crushed material In this embodiment, a high electromagnetic wave absorption rate can be achieved even if the material is 100 mass % of the material of this embodiment. crushed material Although a high electromagnetic wave absorption rate can be achieved even if crushed material The proportion of is preferably 50% by mass or less, and may be 45% by mass or less. The same applies to the reflectance calculated according to formula (B) and the transmittance calculated according to formula (C) described later.

[0015] The absorbency is preferably 53.0% or more, more preferably 55.0% or more, even more preferably 58.0% or more, and even more preferably 60.0% or more. The upper limit is ideally 100%, but even if it is 90.0% or less, the required performance is sufficiently met.

[0016] In this embodiment, it is preferable that the crushed material (or a material containing the crushed material) has a low reflectance of electromagnetic waves when molded into a 2 mm thick molded body. Specifically, in this embodiment, when the crushed material (or a material containing the crushed material) is molded into a molded body 2 mm thick (preferably, 100 mm x 100 mm x 2 mm thick), it is preferable that the reflectivity calculated according to formula (B) at a frequency of 76.5 GHz is 40.0% or less. Formula (B)

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[0017] The reflectance is preferably 35.0% or less, more preferably 30.0% or less, and even more preferably 26.0% or less. The lower limit is ideally 0%, but even if it is 5.0% or more, or even 10.0% or more, the required performance is sufficiently met.

[0018] In this embodiment, it is preferable that the crushed material (or a material containing the crushed material) has low transmittance when molded into a molded article having a thickness of 2 mm. In this embodiment, when the crushed material (or a material containing the crushed material) is molded into a molded body 2 mm thick (preferably 100 mm x 100 mm x 2 mm thick), it is preferable that the transmittance calculated according to formula (C) at a frequency of 76.5 GHz is 25.0% or less. Formula (C)

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[0019] The transmittance is preferably 23.0% or less, and more preferably 20.0% or less. The lower limit is ideally 0%, but even if it is 5.0% or more, the required performance is sufficiently met.

[0020] In this embodiment, when the crushed material (or a material containing the crushed material) is molded into a 2 mm thick molded body, it is preferable that the absorption coefficient calculated according to the above formula (A), the reflectance calculated according to the above formula (B), and the transmittance calculated according to the above formula (C) all satisfy the above requirements.

[0021] In addition, the resin composition ( crushing As for the resin composition (e.g., virgin pellets, resin composition to be blended into the material described later), when molded into a molded article of 2 mm thickness (preferably, 100 mm × 100 mm × 2 mm thickness) in the same manner as above, it is preferable that the resin composition satisfies one or more of the absorbance calculated according to the above formula (A), the reflectance calculated according to the above formula (B), and the transmittance calculated according to the above formula (C), and it is more preferable that the resin composition satisfies all of them.

[0022] In particular, the absorption rate calculated according to the above formula (A) when the crushed material (or a material containing the crushed material) is molded into a 2 mm thick molded body relative to the absorption rate calculated according to the above formula (A) when the resin composition (e.g., virgin pellets) used in this embodiment is molded into a 2 mm thick molded body (preferably 100 mm × 100 mm × 2 mm thick), i.e., (absorption rate of material / absorption rate of resin composition) × 100 (unit: %), is preferably 30% or more, more preferably 40% or more, even more preferably 50% or more, even more preferably 55% or more, and even more preferably 60% or more. The upper limit is ideally 100%, and may be 99.9% or less.

[0023] In particular, the reflectance calculated according to the above formula (B) when the crushed material (or a material containing the crushed material) is molded into a 2 mm thick molded body, relative to the reflectance calculated according to the above formula (B) when the resin composition (e.g., virgin pellets) used in this embodiment is molded into a 2 mm thick molded body (preferably 100 mm × 100 mm × 2 mm thick), i.e., (reflectance of material / reflectance of resin composition) × 100 (unit: %), is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, even more preferably 25% or less, and even more preferably 20% or less. The lower limit is ideally 0%, and may be 1% or more.

[0024] In particular, the transmittance calculated according to formula (C) when the crushed material (or a material containing the crushed material) is molded into a 2 mm thick molded body relative to the transmittance calculated according to formula (C) when the resin composition (e.g., virgin pellets) used in this embodiment is molded into a 2 mm thick molded body (preferably 100 mm × 100 mm × 2 mm thick), i.e., (transmittance of material / transmittance of resin composition) × 100 (unit: %), is preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less, and even more preferably 8% or less. The lower limit is ideally 0%, and may be 1% or more.

[0025] In this embodiment, when the crushed material (or a material containing the crushed material) is molded into a 2 mm thick molded body, the surface resistance according to IEC60093 is 1.0 × 10 8 Ω or more is preferable, and 1.0×10 9 Ω or more is more preferable, and 1.0×10 10 It is more preferable that the resistance is 1.0×10 Ω or more. 11 Ω or more is more preferable, and 1.0×10 12 Ω or more is more preferable, and 1.0×10 13 It is even more preferable that the resistance is 1.0×10 Ω or more. 14It is particularly preferable that the resistance is 1.0×10 Ω or more. 16 Ω or less is preferable, and 1.0×10 15 It is more preferable that the hardness is Ω or less. By setting the hardness in this range, the electromagnetic wave absorption rate of the obtained molded article tends to be higher.

[0026] The term "virgin pellets" refers to pellets made by melt-kneading a thermoplastic resin, carbon nanotubes, and other components as needed. Virgin pellets that are re-melted and re-pelletized are called "re-pellets" and are included in recycled products.

[0027] <Thermoplastic resin> Next, the thermoplastic resin contained in the resin composition used in this embodiment will be described. Preferred examples of the thermoplastic resin used in this embodiment include polyester resin (thermoplastic polyester resin); polyamide resin; polycarbonate resin; polystyrene-based resin; polyolefin resin such as polyethylene resin, polypropylene resin, and cyclic cycloolefin resin; polyacetal resin; polyimide resin; polyetherimide resin; polyurethane resin; polyphenylene ether resin; polyphenylene sulfide resin; polysulfone resin; polymethacrylate resin; and the like, with polyester resin (thermoplastic polyester resin), polyamide resin, polycarbonate resin, and polyphenylene ether resin being preferred. In this embodiment, the thermoplastic resin preferably includes a polyester resin, and more preferably includes a polybutylene terephthalate resin.

[0028] In this embodiment, the thermoplastic resin (for example, polyester resin (thermoplastic polyester resin), polyamide resin, polycarbonate resin, and polyphenylene ether resin) may be a linear polymer or a branched polymer having a branched structure. In this embodiment, the thermoplastic resin preferably has a small branching structure. For example, the thermoplastic resin used in this embodiment preferably has a degree of branching (DB) of less than 10%, more preferably 5% or less, and even more preferably 3% or less. Here, the degree of branching is defined as DB(%) = 100 × (T + Z) / (T + Z + L), where T is the average number of terminally bonded monomer units, Z is the average number of monomer units forming branches, and L is the average number of linearly bonded monomer units (within the macromolecules of each substance). Each thermoplastic resin will be described in detail below.

[0029] <<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 used in this embodiment is a polyester resin having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded, and includes, in addition to polybutylene terephthalate resin (homopolymer), 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 dL / g or more, more preferably 0.6 dL / g or more. By setting the intrinsic viscosity to 0.5 dL / g or more, the mechanical strength of the resulting resin composition tends to be further improved. The intrinsic viscosity is preferably 2.00 dL / g, more preferably 1.50 dL / g or less, even more preferably 1.30 dL / g or less, even more preferably 1.25 dL / g or less, even more preferably 1.23 dL / g or less, and may even be 1.19 dL / g or less, 1.17 dL / g or less, 1.15 dL / g or less, 1.13 dL / g or less, 1.07 dL / g or less, 1.05 dL / g or less, 1.00 dL / g or less, or 0.97 dL / g or less. By setting the intrinsic viscosity to 2.0 dL / g or less, the fluidity of the resin composition tends to be further improved, and moldability tends to be improved. In particular, when a masterbatch of carbon nanotubes with polybutylene terephthalate resin is blended into a resin composition in which polybutylene terephthalate resin is the main component of the thermoplastic resin (e.g., 80% by mass or more of the resin component), the lower the intrinsic viscosity of the main component polybutylene terephthalate resin, the easier it is for the carbon nanotubes to disperse, which tends to result in improved electromagnetic wave absorption properties. 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).

[0036] 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.

[0037] 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.

[0038] 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.

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

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

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

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

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

[0044] <<Polycarbonate resin>> Polycarbonate resins are homopolymers or copolymers, which may be branched, obtained by reacting a dihydroxy compound or a small amount of a polyhydroxy compound with phosgene or a carbonate diester. The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by the conventionally known phosgene method (interfacial polymerization method) or melt method (ester interchange method) can be used.

[0045] The dihydroxy compound used as the raw material is preferably an aromatic dihydroxy compound, such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, or 4,4-dihydroxydiphenyl, with bisphenol A being preferred. It is also possible to use a compound in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compound.

[0046] Among the polycarbonate resins mentioned above, aromatic polycarbonate resins derived from 2,2-bis(4-hydroxyphenyl)propane or aromatic polycarbonate copolymers derived from 2,2-bis(4-hydroxyphenyl)propane and other aromatic dihydroxy compounds are preferred. Also, copolymers mainly composed of aromatic polycarbonate resins, such as copolymers with polymers or oligomers having a siloxane structure, may be used. Furthermore, two or more of the above-mentioned polycarbonate resins may be mixed and used.

[0047] To adjust the molecular weight of the polycarbonate resin, a monovalent aromatic hydroxy compound may be used, such as m- and p-methylphenol, m- and p-propylphenol, p-tert-butylphenol, and p-long-chain alkyl-substituted phenol.

[0048] The viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 13,000 or more. By using a polycarbonate resin having a viscosity average molecular weight of 5,000 or more, the mechanical strength of the resulting resin composition tends to be further improved. Furthermore, the viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 60,000 or less, more preferably 40,000 or less, and even more preferably 30,000 or less. By using a polycarbonate resin having a viscosity average molecular weight of 60,000 or less, the flowability of the resin composition tends to be improved, and moldability tends to be improved. When two or more types of polycarbonate resins are contained, it is preferable that the mixture satisfies the above range (hereinafter, the same applies to molecular weight).

[0049] In this embodiment, the viscosity average molecular weight (Mv) of the polycarbonate resin is a value calculated from the intrinsic viscosity ([η]) obtained by measuring the viscosity of a methylene chloride solution of the polycarbonate resin at 20°C using an Ubbelohde viscometer, and then using the following Schnell viscosity formula: [η]=1.23×10 -4 Mv 0.83

[0050] The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by either the phosgene method (interfacial polymerization method) or the melt method (ester interchange method) can be used. Also preferred is a polycarbonate resin produced by the melt method and then subjected to post-treatment to adjust the amount of terminal OH groups.

[0051] <<Polyphenylene ether resin>> In this embodiment, a known polyphenylene ether resin can be used, for example, a polymer having a structural unit represented by the following formula in its main chain (preferably a polymer in which the structural unit represented by the following formula accounts for 90 mol % or more of all structural units excluding terminal groups). The polyphenylene ether resin may be either a homopolymer or a copolymer.

[0052] [ka] (wherein two R a each independently represents a hydrogen atom, a halogen atom, a primary or secondary alkyl group, an aryl group, an aminoalkyl group, a halogenated alkyl group, a hydrocarbonoxy group, or a halogenated hydrocarbonoxy group, and two R beach independently represents a hydrogen atom, a halogen atom, a primary or secondary alkyl group, an aryl group, a halogenated alkyl group, a hydrocarbonoxy group, or a halogenated hydrocarbonoxy group. a cannot both become hydrogen atoms.)

[0053] R a and R b are each independently preferably a hydrogen atom, a primary or secondary alkyl group, or an aryl group. Preferred examples of primary alkyl groups include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-amyl group, an isoamyl group, a 2-methylbutyl group, a 2,3-dimethylbutyl group, a 2-, 3-, or 4-methylpentyl group, or a heptyl group. Preferred examples of secondary alkyl groups include an isopropyl group, a sec-butyl group, or a 1-ethylpropyl group. In particular, R a is preferably a primary or secondary alkyl group having 1 to 4 carbon atoms or a phenyl group. b is preferably a hydrogen atom.

[0054] Suitable homopolymers of polyphenylene ether resins include, for example, polymers of 2,6-dialkylphenylene ethers such as poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene ether), poly(2,6-dipropyl-1,4-phenylene ether), poly(2-ethyl-6-methyl-1,4-phenylene ether), and poly(2-methyl-6-propyl-1,4-phenylene ether). Examples of the copolymer include 2,6-dialkylphenol / 2,3,6-trialkylphenol copolymers such as 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymer, 2,6-dimethylphenol / 2,3,6-triethylphenol copolymer, 2,6-diethylphenol / 2,3,6-trimethylphenol copolymer, and 2,6-dipropylphenol / 2,3,6-trimethylphenol copolymer; graft copolymers in which styrene is graft polymerized onto poly(2,6-dimethyl-1,4-phenylene ether); and graft copolymers in which styrene is graft polymerized onto 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymer.

[0055] In this embodiment, the polyphenylene ether resin is preferably poly(2,6-dimethyl-1,4-phenylene) ether or a 2,6-dimethylphenol / 2,3,6-trimethylphenol random copolymer. Also suitable is a polyphenylene ether resin having a specified number of terminal groups and copper content, as described in JP-A-2005-344065.

[0056] The polyphenylene ether resin preferably has an intrinsic viscosity of 0.2 to 0.8 dL / g, more preferably 0.3 to 0.6 dL / g, measured in chloroform at 30°C. By setting the intrinsic viscosity to 0.2 dL / g or higher, the mechanical strength of the molded article tends to be improved, while by setting the intrinsic viscosity to 0.8 dL / g or lower, the fluidity of the resin composition tends to be improved, making molding easier. Furthermore, two or more polyphenylene ether resins with different intrinsic viscosities may be used in combination to achieve an intrinsic viscosity within this range.

[0057] The method for producing the polyphenylene ether resin used in the present embodiment is not particularly limited, and may be a known method, for example, a method of oxidatively polymerizing a monomer such as 2,6-dimethylphenol in the presence of an amine copper catalyst, in which the intrinsic viscosity can be controlled within a desired range by selecting the reaction conditions. The intrinsic viscosity can be controlled by selecting conditions such as the polymerization temperature, polymerization time, and catalyst amount.

[0058] <<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, and may be either aliphatic polyamide resins or semi-aromatic polyamide resins. Specific examples include polyamide 6, 11, 12, 46, 66, 610, 612, 6I, 6 / 66, 6T / 6I, 6 / 6T, 66 / 6T, 66 / 6T / 6I, 9T, 10T, xylylenediamine-based polyamide resins (details of which will be described later), polytrimethylhexamethylene terephthalamide, polybis(4-aminocyclohexyl)methanedodecamide, polybis(3-methyl-4-aminocyclohexyl)methanedodecamide, and polyundecamethylene hexahydroterephthalamide. The "I" in the above text represents an isophthalic acid component, and the "T" represents a terephthalic acid component. Regarding polyamide resins, the description in paragraphs 0011 to 0013 of JP 2011-132550 A can be found, the contents of which are incorporated herein by reference.

[0059] The polyamide resin used in this embodiment is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, and is preferably a xylylenediamine-based polyamide resin in which 50 mol% or more of the diamine-derived structural units are derived from xylylenediamine. The diamine-derived structural units of the xylylenediamine-based polyamide resin are preferably derived from at least one of meta-xylylenediamine and para-xylylenediamine by 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more. The dicarboxylic acid-derived structural units of the xylylenediamine-based polyamide resin are preferably derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms by 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more. Suitable α,ω-straight chain aliphatic dibasic acids having 4 to 20 carbon atoms include adipic acid, sebacic acid, suberic acid, dodecanedioic acid, and eicodionic acid, with adipic acid and sebacic acid being more preferred.

[0060] 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.

[0061] 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.

[0062] The content of the thermoplastic resin in the resin composition used in this embodiment is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and even more preferably 50% by mass or more. When the resin composition does not contain an inorganic filler, the content of the thermoplastic resin in the resin composition is more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. By setting the content to be equal to or greater than the lower limit, fluidity during injection molding tends to be further improved. Furthermore, the content of the thermoplastic resin is preferably 99% by mass or less. When the resin composition contains an inorganic filler, the content of the thermoplastic resin in the resin composition is more preferably 90% by mass or less, even more preferably 85% by mass or less, and even more preferably 80% by mass or less. By setting the content to be equal to or less than the upper limit, the amount of warpage of the molded product tends to be more effectively reduced. The resin composition used in the present embodiment may contain only one type of 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.

[0063] <Carbon nanotubes> The resin composition used in this embodiment contains carbon nanotubes. The carbon nanotubes are single-walled carbon nanotubes and / or multi-walled carbon nanotubes, and preferably contain at least multi-walled carbon nanotubes. Carbon materials partially having a carbon nanotube structure can also be used. The carbon nanotubes are not limited to a cylindrical shape, and may have a coiled shape with a spiral at a pitch of 1 μm or less. Carbon nanotubes are commercially available, and examples thereof include carbon nanotubes available from Bayer MaterialScience, Nanosil, Showa Denko K.K., and Hyperion Catalysis International, Inc. In addition to the name carbon nanotubes, they are also called graphite fibrils, carbon fibrils, etc.

[0064] 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.

[0065] The content of carbon nanotubes in the resin composition used in this embodiment is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and may be 0.2% by mass or more, or even 0.4% by mass or more. By making the content equal to or greater than the lower limit, electromagnetic wave absorption properties are effectively exhibited. Furthermore, the content of carbon nanotubes in the resin composition used in this embodiment is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, even more preferably 3% by mass or less, may be 2% by mass or less, or even 1% by mass or less. By making the content equal to or less than the upper limit, the fluidity of the resin tends to be further improved.

[0066] The resin composition used in this embodiment also preferably contains 0.1 parts by mass or more of carbon nanotubes per 100 parts by mass of the thermoplastic resin. By setting the carbon nanotubes at or above the lower limit, electromagnetic wave absorption properties are effectively exhibited. The resin composition used in this embodiment also preferably contains 10.0 parts by mass or less of carbon nanotubes per 100 parts by mass of the thermoplastic 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 even 2.5 parts by mass or less, particularly 1.5 parts by mass or less. Setting the carbon nanotubes at or below the upper limit tends to further improve the fluidity of the resin. The resin composition used in this 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.

[0067] <Other ingredients> The resin composition used in 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 inorganic fillers and various resin additives. Note that one type of other component may be contained, or two or more types may be contained in any combination and ratio.

[0068] Examples of various resin additives include stabilizers, mold release agents, flame retardants, pigments, dyes, UV absorbers, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, dispersants, antibacterial agents, etc. The resin composition used in this embodiment preferably contains at least one of stabilizers and mold release agents. The resin composition used in this embodiment is adjusted so that the total of the thermoplastic resin, carbon nanotubes, and other optional components is 100% by mass. It is also preferable that the total of the thermoplastic resin, carbon nanotubes, stabilizer, and release agent in the resin composition used in this embodiment is 99% by mass or more. It is also preferable that the total of the thermoplastic resin, carbon nanotubes, inorganic filler (preferably glass fiber), stabilizer, and release agent in the resin composition used in this embodiment is 99% by mass or more.

[0069] <<Stabilizer>> The resin composition used in 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.

[0070] The resin composition used in this embodiment preferably contains 0.01 parts by mass or more of the stabilizer relative to 100 parts by mass of the 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 thermoplastic resin. The resin composition used in 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.

[0071] <<Release Agent>> The resin composition used in this 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.

[0072] The resin composition used in this embodiment preferably contains 0.01 parts by mass or more of a release agent relative to 100 parts by mass of the 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 is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and even more preferably 0.8 parts by mass or less relative to 100 parts by mass of the thermoplastic resin. 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.

[0073] <<Inorganic fillers>> The resin composition used in this embodiment may or may not contain an inorganic filler. By containing an inorganic filler, the mechanical strength of the obtained molded article can be improved. The inorganic filler that can be used in this embodiment is not particularly limited in terms of type, etc., and may be any of fibers, fillers, beads, etc., with fibers being preferred. In particular, glass fibers are preferable because they also function as a dispersant for carbon nanotubes.

[0074] When the inorganic filler is a fiber, it may be a short fiber or a long fiber. When the inorganic filler is short fibers, fillers, beads, or the like, the resin composition used in this embodiment may be, for example, pellets, powdered pellets, or films formed from the pellets. When the inorganic filler is a long fiber, examples of the inorganic filler include long fibers for so-called unidirectional (UD) materials, sheet-like long fibers such as woven fabrics and knitted fabrics, etc. When using these long fibers, the components other than the inorganic filler of the resin composition used in this embodiment can be impregnated into the inorganic filler in the form of a sheet-like long fiber to form a sheet-like resin composition (for example, a prepreg).

[0075] Raw materials for inorganic fillers include inorganic substances such as glass, carbon (carbon fiber, etc.), alumina, boron, ceramics, and metals (steel, etc.), and organic substances such as plants (including kenaf, bamboo, etc.), aramid, polyoxymethylene, aromatic polyamide, polyparaphenylene benzobisoxazole, and ultra-high molecular weight polyethylene, with glass being preferred.

[0076] The resin composition used in this embodiment preferably contains glass fiber as an inorganic filler. 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.

[0077] 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 used in this embodiment are not significantly impaired.

[0078] When the resin composition used in this embodiment contains an inorganic filler (preferably glass fiber), the content thereof is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, relative to 100 parts by mass of the thermoplastic resin. By setting the content at or above the lower limit, the mechanical strength of the obtained molded article tends to be further increased. Furthermore, the content of the inorganic filler (preferably glass fiber) is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, even more preferably 80 parts by mass or less, and even more preferably 75 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin. 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.

[0079] When the resin composition used in this embodiment contains an inorganic filler (preferably glass fiber), the content thereof in the resin composition is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 25% by mass or more. The content of the inorganic filler (preferably glass fiber) in the resin composition is more preferably 50% by mass or less, even more preferably 45% by mass or less, even more preferably 40% by mass or less, and even more preferably 35% by mass or less. By setting the content at or above the lower limit, mechanical strength tends to be further increased. By setting the content at or below the upper limit, the appearance of the molded article tends to be improved, and the fluidity of the resin composition when melted tends to be further improved. The resin composition used in this embodiment may contain only one type of inorganic filler (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.

[0080] The resin composition used in this embodiment can be produced by a conventional method for producing a resin composition containing a thermoplastic resin. For example, it can be obtained by melt-kneading a thermoplastic resin, carbon nanotubes, and other components that are blended as needed. The carbon nanotubes are preferably blended as a masterbatch with a thermoplastic resin. By blending the carbon nanotubes as a masterbatch with a thermoplastic resin, the dispersibility of the conductive material in the thermoplastic resin can be effectively improved. The concentration of carbon nanotubes in the masterbatch is preferably 1% by mass or more, and more preferably 5% by mass or more, and also preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 20% by mass or less. By setting the concentration within the above upper limit or less and lower limit or greater, the dispersibility of the carbon nanotubes in the thermoplastic resin tends to be further improved.

[0081] The components may be mixed in advance and fed to the extruder all at once, or the components may be mixed in advance without mixing, or only a portion of the components may be mixed in advance, and then fed to the extruder using a feeder. The extruder may be a single-screw extruder or a twin-screw extruder. When glass fibers are compounded, they are preferably fed from a side feeder midway through the cylinder of the extruder. The heating temperature during melt-kneading can usually be appropriately selected from the range of 170 to 350°C.

[0082] <Material> Next, the materials of this embodiment will be described. The material of this embodiment includes pellets obtained from a resin composition containing a thermoplastic resin and carbon nanotubes, and the crushed material of this embodiment.

[0083] The pellets obtained from the resin composition containing the thermoplastic resin and the carbon nanotubes may be virgin pellets or repellets. In this embodiment, the pellets are preferably virgin pellets. In this embodiment, the mass ratio of the pellets (preferably virgin pellets) to the crushed material is preferably 10-90:90-10. Furthermore, when the total of the pellets and the crushed material is 100 parts by mass, the mass ratio of the crushed material is more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more. By setting the mass ratio at or above the lower limit, recycled resin can be used efficiently. The mass ratio of the crushed material is preferably 90 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less. By setting the mass ratio at or below the upper limit, a decrease in the mechanical strength of the resulting molded product can be suppressed.

[0084] The material of this embodiment may contain only one type of pellets and crushed material, or may contain two or more types. When two or more types are contained, it is preferable that the total amount is within the above range. The material of this embodiment may contain pellets and crushed material in total, accounting for 90% by mass or more of the total, but may also contain other components. Examples of other components include virgin or recycled thermoplastic resins, inorganic fillers, and other resin additives. For these components, refer to the descriptions of the thermoplastic resins, inorganic fillers, and resin additives described in the section on resin compositions above.

[0085] The thermoplastic resin contained in the pellets used in this embodiment preferably contains a polybutylene terephthalate resin. Moreover, the pellets used in this embodiment preferably further contain 0.1 to 10.0 parts by mass of the carbon nanotubes relative to 100 parts by mass of the thermoplastic resin. Moreover, the pellets used in this embodiment preferably further contain 10 to 100 parts by mass of an inorganic filler relative to 100 parts by mass of the thermoplastic resin. Other than that, the pellets used in this embodiment are the same as those of the resin composition described above, and the preferred ranges are also the same.

[0086] <Molded body> The compact of this embodiment is formed from the crushed material of this embodiment or the material of this embodiment. Furthermore, the method for producing a molded body in this embodiment includes molding the crushed material of the embodiment or the material of the embodiment. The molding method for producing the molded body can be arbitrarily adopted for the resin composition containing thermoplastic resin.Examples thereof include injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted hollow molding, molding using a heat-insulating mold, molding using a rapid heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding), extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, etc., and injection molding or extrusion molding is preferred, and injection molding is more preferred.

[0087] In this embodiment, the shape of the molded product is not particularly limited, and examples include molded products such as injection molded products and extrusion molded products (for example, films).

[0088] <Application> In this embodiment crushed material The material or molded article 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]

[0089] 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.

[0090] 1. Raw materials The following raw materials were used: In Table 1 below, PBT stands for polybutylene terephthalate resin, and CNT stands for carbon nanotubes. [Table 1]

[0091] Example 1, Comparative Example 1 <Production of Resin Composition (Pellets)> The components listed in Table 1 (amounts in parts by weight) except for the inorganic filler were placed in a stainless steel tumbler and mixed for 1 hour. The resulting mixture was fed into a co-rotating intermeshing twin-screw extruder (Japan Steel Works, Ltd., "TEX-30α," 32 mm screw diameter, L / D = 42) through the main feed port. The barrel temperature of the first mixing section was set to 260°C for plasticization, and the inorganic filler (glass fiber) was fed through a side feeder in the proportions shown in Table 2. After adding the inorganic filler, the barrel temperature was set to 250°C, and the mixture was melt-mixed at a discharge rate of 40 kg / h and a screw rotation speed of 200 rpm. The mixture was then extruded as a strand using a four-hole nozzle (circular, 4 mm diameter, 1.5 cm long). The extruded strand was introduced into a water bath for cooling, then inserted into a pelletizer and cut to obtain a resin composition (virgin pellets).

[0092] <76.5GHz electromagnetic wave absorption rate, reflectance, transmittance> The virgin pellets obtained above were injection molded in an injection molding machine ("NEX80" manufactured by Nissei Plastic Industrial Co., Ltd.) at a cylinder temperature of 260°C and a mold temperature of 80°C to obtain test pieces measuring 100 mm x 100 mm x 2 mm thick. Using the obtained test pieces, the 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. The test piece obtained above was subjected to Granulator GSL180 / 180 manufactured by ZERMA. crushed material The majority of the size is approximately 3.0mm x 3.0mm x 2.0mm. crushing And crushed material ( crushed material We obtained a compound called A. Furthermore, the crushed material A obtained above was subjected to the same method as above to obtain a test piece of 100 mm x 100 mm x 2 mm thick. crushing did crushed material The process of obtaining a test piece again was counted as one recycling process, and finally, a test piece that had been through five recycling processes was obtained. The electromagnetic wave absorption rate and electromagnetic wave reflectance rate after five recycling processes were calculated relative to the virgin product ( crushed material 100% absorption rate maintenance rate, crushed material 100% reflectivity retention rate). The closer to 100%, the better the retention rate.

[0093] The crushed material A obtained above and virgin pellets were mixed at a mass ratio of 30:70, and test pieces measuring 100 mm x 100 mm x 2 mm were obtained in the same manner as above. This constitutes one recycling process, and test pieces that had undergone five recycling processes were finally obtained. The test pieces obtained after the virgin product, the second recycling, and the fifth recycling were measured for 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 as follows. We also calculated the electromagnetic wave absorption rate and electromagnetic wave reflectance rate retention rate after five recycling cycles compared to virgin products.

[0094] A Keysight network analyzer "N5252A" was used to measure various electromagnetic wave characteristics. 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

[0095] Formula (B)

number

[0096] Formula (C)

number

[0097] [Table 2]

[0098] In Table 2 above, the content of the conductive material (CTN, carbon fiber) indicates the mass ratio (unit: mass %) of the conductive material in the resin composition. As is clear from the above results, the present embodiment crushed material The comparative example maintained excellent electromagnetic wave properties even after recycling. crushed material However, the electromagnetic wave characteristics of recycled plastic have deteriorated significantly. [Explanation of symbols]

[0099] 1. Resin composition (pellets) 2 Injection molding machine 3 Passed products 4 Rejected products 5 Scraps 6 Crusher 7. Crushed material 8 Reuse

Claims

1. A method for producing a thermoplastic resin product, comprising: pellets obtained from a resin composition containing a thermoplastic resin and carbon nanotubes; The present invention relates to a crushed material of a resin composition containing a thermoplastic resin and carbon nanotubes, and when the crushed material is molded into a molded body having a thickness of 2 mm, the crushed material has an absorption rate of 40.0 to 100% at a frequency of 76.5 GHz calculated according to formula (A), the thermoplastic resin contained in the pellets includes polybutylene terephthalate resin, The mass ratio of the pellets to the crushed material is 10 to 90:90 to 10. 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 material of claim 1 , wherein the thermoplastic resin contained in the crushed material comprises polybutylene terephthalate resin.

3. A material described in claim 1 or 2, wherein the resin composition constituting the crushed material contains 0.1 to 10.0 parts by mass of the carbon nanotubes per 100 parts by mass of the thermoplastic resin.

4. The material according to any one of claims 1 to 3, wherein the resin composition constituting the crushed material is a recycled resin composition containing a thermoplastic resin and carbon nanotubes.

5. The material according to any one of claims 1 to 4, wherein the resin composition constituting the crushed material is a molded body formed from a resin composition containing a thermoplastic resin and carbon nanotubes.

6. The material according to any one of claims 1 to 5, wherein the resin composition constituting the crushed material further contains 10 to 100 parts by mass of an inorganic filler per 100 parts by mass of thermoplastic resin.

7. In the resin composition constituting the crushed material, the thermoplastic resin contains polybutylene terephthalate resin, The resin composition constituting the crushed material contains 0.1 to 10.0 parts by mass of the carbon nanotubes per 100 parts by mass of the thermoplastic resin, the resin composition constituting the crushed material is a recycled product and / or a molded product of a resin composition containing a thermoplastic resin and carbon nanotubes, The material according to any one of claims 1 to 6, wherein the resin composition constituting the crushed material further contains 10 to 100 parts by mass of an inorganic filler per 100 parts by mass of thermoplastic resin.

8. The material according to any one of claims 1 to 7, wherein the pellets are virgin pellets.

9. The material according to claim 7 or 8.

9. The material according to any one of claims 1 to 8, wherein the pellet further contains 0.1 to 10.0 parts by mass of the carbon nanotubes per 100 parts by mass of the thermoplastic resin.

10. The material according to any one of claims 1 to 9, wherein the pellets further contain 10 to 100 parts by mass of an inorganic filler per 100 parts by mass of the thermoplastic resin.

11. A molded article made from the material according to any one of claims 1 to 10.

12. A method for producing a molded body, comprising molding the material according to any one of claims 1 to 10.

13. The method for producing a molded article according to claim 12, wherein the material is formed by injection molding or extrusion molding.

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