Thermoplastic resin composition and resin molded body

Abstract

The problem is solved by a thermoplastic resin composition containing a thermoplastic resin (A) and carbon nanotubes (B), where the carbon nanotubes (B) satisfy both of (1) and (2) below. (1) The total metal content is 10,000 ppm or less. (2) The half-value width of the diffraction peak of the (002) plane in powder X-ray diffraction analysis is 2.0-6.0°.

Description

Thermoplastic resin composition and resin molded article

[0001] The present disclosure relates to a thermoplastic resin composition and a resin molded article.

[0002] Resin molded products are easy to process and are therefore used in a wide range of fields, including automobile parts, medical parts, food containers, and electrical and electronic equipment parts. In particular, resin molded products containing carbon nanotubes, a carbon material, are being actively studied in order to enhance their decorative properties and impart functionality.

[0003] Carbon nanotubes, which have a cylindrical structure composed of graphite layers, are chemically stable and can be mass-produced using the economical and productive chemical vapor deposition method. They are widely used. Furthermore, they possess electrical conductivity and mechanical toughness. By blending carbon nanotubes with thermoplastic resins, various functionalities can be imparted to molded articles, including electrical conductivity, thermal conductivity, improved mechanical strength, and electromagnetic wave absorption. Therefore, carbon nanotubes are finding applications in a variety of fields, including electronics (e.g., transistor elements, wiring), energy (e.g., fuel cell electrode materials, photovoltaic power generation devices, gas storage devices), electron emission (e.g., flat panel devices), chemistry (e.g., adsorbents, catalysts, sensors), and composite materials (e.g., conductive plastics, reinforced materials, flame-retardant nanocomposites).

[0004] Resin compositions containing carbon nanotubes have high electrical conductivity that cannot be achieved by carbon black, and are therefore widely used, particularly for conductive applications, in a variety of fields such as automobile parts (Patent Documents 1 and 2).

[0005] JP 2016-108524 A JP 2022-076641 A

[0006] In thermoplastic resin compositions, conductive paths are formed when carbon nanotubes dispersed in the thermoplastic resin come into contact with each other, imparting electrical conductivity. Therefore, ideally, the more uniformly dispersed fibrous carbon nanotubes are in the thermoplastic resin, the more efficient the conductive network that can be formed. However, carbon nanotubes have high cohesion, making it difficult to obtain a uniformly dispersed thermoplastic resin composition. Furthermore, aggregated carbon nanotubes increase the viscosity of the thermoplastic resin composition, reducing its flowability. This can lead to uneven dispersion during molding, resulting in variations in surface resistance depending on the location of the molded product and a large molding shrinkage rate. Furthermore, in high-temperature environments, oxidation and decomposition reactions of the thermoplastic resin can cause problems with thermal stability over time.

[0007] Therefore, an object of the present disclosure is to provide a resin molded article that suppresses aggregation of carbon nanotubes in a thermoplastic resin composition, has excellent uniformity of carbon nanotubes when molded, and has high electrical conductivity, and further has excellent thermal stability over time.

[0008] That is, the present disclosure includes the following embodiments. The embodiments of the present disclosure are not limited to the following. [1]: A thermoplastic resin composition comprising a thermoplastic resin (A) and carbon nanotubes (B), wherein the carbon nanotubes (B) satisfy both of the following (1) and (2): (1) The total metal content is 10,000 ppm or less. (2) In powder X-ray diffraction analysis, the half-width of the diffraction peak of the (002) plane is 2.0 to 6.0°. [2]: The thermoplastic resin composition according to [1], wherein the carbon nanotubes (B) have an ash content of 0.001 to 1.0 mass% when heated at 900°C for 1 hour. [3]: The thermoplastic resin composition according to [1] or [2], wherein the iron content of the carbon nanotubes (B) is 10 to 5,000 ppm. [4]: ​​The carbon nanotubes (B) have a volume resistivity of 1.0 x 10 －３ ~3.0 x 10 －２ [5]: The thermoplastic resin composition according to any one of [1] to [3], wherein the carbon nanotubes (B) have a BET specific surface area of ​​200 to 600 m ２ / g. [6]: The thermoplastic resin composition according to any one of [1] to [5], wherein the cobalt content of the carbon nanotubes (B) is 10 to 1,000 ppm. [7]: The thermoplastic resin composition according to any one of [1] to [6], wherein the thermoplastic resin (A) comprises at least one selected from the group consisting of polyolefin resins, acrylonitrile-butadiene-styrene copolymer resins, polycarbonate resins, polyamide resins, and polyester-based resins. [8]: The thermoplastic resin composition according to any one of [1] to [6], wherein the thermoplastic resin (A) comprises at least one selected from the group consisting of polyethylene resins, polypropylene resins, and cycloolefin resins. [9]: The thermoplastic resin composition according to any one of [1] to [8], wherein the total metal content of the thermoplastic resin composition is 3,000 ppm or less.

[10] : The thermoplastic resin composition according to any one of [1] to [9], containing 0.1 to 30 parts by mass of carbon nanotubes (B) per 100 parts by mass of thermoplastic resin (A).

[11] : A thermoplastic resin composition comprising a thermoplastic resin (A) and carbon nanotubes (B), wherein the carbon nanotubes (B) are contained in an amount of 0.1 to 30 parts by mass per 100 parts by mass of thermoplastic resin (A), and wherein the carbon nanotubes (B) have a half-width of a diffraction peak of a (002) plane of 2.0 to 6.0° in powder X-ray diffraction analysis, and the total metal content of the thermoplastic resin composition is 3,000 ppm or less.

[12] : The thermoplastic resin composition according to any one of [1] to

[10] , wherein the total metal content is 500 to 7,200 ppm in (1), and wherein the half-width of a diffraction peak of a (002) plane of 2.0 to 3.5° in powder X-ray diffraction analysis.

[13] : The thermoplastic resin composition according to

[12] , wherein the iron content of the carbon nanotubes (B) is 50 to 4500 ppm and the cobalt content of the carbon nanotubes (B) is 20 to 700 ppm.

[14] : A resin molded product formed using the thermoplastic resin composition according to any one of [1] to

[11] .

[0009] According to some embodiments of the present disclosure, by using specific carbon nanotubes, it is possible to provide a thermoplastic resin composition in which aggregation of carbon nanotubes in the thermoplastic resin composition is suppressed and the carbon nanotubes have excellent dispersibility, as well as a resin molded article formed from the thermoplastic resin composition that has excellent conductivity, uniformity, and thermal stability over time.

[0010] Several embodiments of the present disclosure are described in detail below. In this specification, the terms "film" and "sheet" have the same meaning. In this specification, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the lower and upper limit ranges. Furthermore, "carbon nanotubes" may be referred to as "CNTs," and "thermoplastic resin compositions" may be referred to as "resin compositions." Unless otherwise noted, the various components appearing in this specification may be used independently, either singly or in combination.

[0011] Thermoplastic Resin Composition A thermoplastic resin composition according to some embodiments of the present disclosure will be described. In some embodiments of the present disclosure, the thermoplastic resin composition is used to form a resin molded article. The thermoplastic resin composition comprises a thermoplastic resin (A) and carbon nanotubes (B), and the carbon nanotubes (B) satisfy both of the following (1) and (2). This makes it possible to provide a resin molded article with excellent conductivity, uniformity, and thermal stability over time. (1) The total metal content is 10,000 ppm or less. (2) In powder X-ray diffraction analysis, the half-width of the diffraction peak of the (002) plane is 2.0 to 6.0°.

[0012] In some embodiments of the present disclosure, the thermoplastic resin composition uses carbon nanotubes (B) having a total metal content and a half-width of an X-ray diffraction peak within a specific range, thereby achieving excellent dispersibility of carbon nanotubes in the thermoplastic resin composition. As a result, the resulting resin molded product has high conductivity, excellent carbon nanotube uniformity, and good thermal stability over time. In the present disclosure, the thermoplastic resin composition contains a thermoplastic resin (A) as a main component, and the carbon nanotubes (B) are dispersed in the thermoplastic resin (A). The thermoplastic resin composition may be in the form of pellets, powder, granules, beads, blocks, molded products, etc. A resin molded product can be obtained by molding the thermoplastic resin composition in a molten or fluid state.

[0013] Carbon nanotubes are manufactured using catalyst particles containing metal components such as iron and cobalt, and may contain metal impurities. However, in some embodiments of the present disclosure, a thermoplastic resin composition contains carbon nanotubes with a total metal content of 10,000 ppm or less, thereby preventing the reduction in the contact rate between carbon nanotubes and the reduction in dispersibility in the thermoplastic resin composition due to these metal impurities. This allows for the production of resin molded articles with excellent conductivity and uniformity. Furthermore, by using carbon nanotubes with metal impurities within the above ranges, which are factors that promote oxidation and decomposition reactions of thermoplastic resins in high-temperature atmospheres, resin molded articles with excellent thermal stability over time can be produced.

[0014] However, simply purifying carbon nanotubes to reduce metal impurities may result in a decrease in dispersibility. Therefore, in some embodiments of the present disclosure, it has been discovered that by using carbon nanotubes with a high crystallinity, in addition to a total metal content, and with an X-ray diffraction peak half width within a specific range, it is possible to obtain a resin molded product with excellent uniformity while maintaining electrical conductivity and suppressing the cohesion between the carbon nanotubes.

[0015] The total metal content in the thermoplastic resin composition is preferably as low as possible, and is preferably 3,000 ppm or less. It is more preferably 2,000 ppm or less, even more preferably 1,500 ppm or less, and particularly preferably 1,000 ppm or less. For example, taking into account the amount of unavoidable metals, the total metal content in the thermoplastic resin composition may be 1 to 3,000 ppm, 10 to 2,000 ppm, 20 to 1,500 ppm, or 50 to 1,000 ppm. The content of metal components contained in the thermoplastic resin composition can be analyzed using inductively coupled plasma (ICP). Specifically, the analysis can be performed according to the method described in the Examples. Not only carbon nanotubes, but also thermoplastic resins may contain metal impurities due to the use of organometallic catalysts such as metallocene catalysts during production. Although metal particles derived from the manufacturing process due to equipment and piping may be contained in the thermoplastic resin composition, by keeping the total metal content within the above range, the contact rate of the carbon nanotubes is improved, the thermoplastic resin and the carbon nanotubes are uniformly mixed, the occurrence of uneven dispersion is prevented, and excellent uniformity is achieved. Furthermore, since oxidation and decomposition reactions of the thermoplastic resin due to metal impurities are suppressed, a resin molded product with excellent electrical conductivity and thermal stability over time can be obtained.

[0016] In order to set the total metal content in the thermoplastic resin composition within this range, it can be controlled not only by the carbon nanotubes used but also by the metal content contained in the thermoplastic resin (A) and the method for producing the thermoplastic resin composition. Specifically, for example, the total metal content of the thermoplastic resin (A) is preferably 1,000 ppm or less, more preferably 700 ppm or less, and particularly preferably 500 ppm or less. By having the total metal content of the thermoplastic resin (A) within the above range, the thermoplastic resin composition can have better thermal stability over time.

[0017] <Thermoplastic Resin (A)> The thermoplastic resin (A) is not particularly limited as long as it is a resin that can be formed into a resin molded body by heat melting. Examples of the thermoplastic resin (A) include polyolefin resins such as polyethylene resin (PE), polypropylene resin (PP), and cycloolefin resin (COP), polyester resins such as polyethylene terephthalate resin (PET) and polybutylene terephthalate resin (PBT), polystyrene resin (PS), polyphenylene ether resin, acrylonitrile-butadiene-styrene copolymer resin (ABS), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyvinyl chloride resin, acrylic resin, polyetherimide resin (PEI), polyphenylene sulfide resin, polyurethane resin (PU), and liquid silicone rubber (LSR). These resins may be used alone or as a composite resin of multiple resins.

[0018] From the viewpoint of dispersibility of the carbon nanotubes (B) in the thermoplastic resin, polyethylene resin (PE), polypropylene resin (PP), cycloolefin resin (COP), acrylonitrile-butadiene-styrene copolymer resin (ABS), polycarbonate resin (PC), polyamide resin (PA), and polyester-based resins are preferred, and at least one selected from the group consisting of polyethylene resin (PE), polypropylene resin (PP), acrylonitrile-butadiene-styrene copolymer resin (ABS), and polycarbonate resin (PC) is more preferred.

[0019] The melt flow rate (hereinafter, MFR) of the thermoplastic resin (A) is preferably in the range of 0.1 to 100 g / 10 min, more preferably in the range of 0.3 to 70 g / 10 min. When the MFR of the thermoplastic resin (A) is in this range, the fluidity during melting is suppressed, and the concentration of the carbon nanotubes (B) on the surface and inside of the resin molded product becomes uniform, making it possible to obtain a resin molded product with a uniform carbon nanotube concentration. The conditions for measuring the MFR of the thermoplastic resin (A) are as follows: a temperature of 190°C and a load of 2.16 kgf for polyethylene resins; a temperature of 280°C and a load of 2.16 kgf for cycloolefin resins; a temperature of 230°C and a load of 2.16 kgf for other polyolefin resins; a temperature of 220°C and a load of 10 kgf for acrylonitrile-butadiene-styrene copolymer resins; a temperature of 280°C and a load of 1.2 kgf for polycarbonate resins; a temperature of 240°C and a load of 2.16 kgf for polyamide resins; and a temperature of 280°C and a load of 1.2 kgf for polyester resins.

[0020] The MFR in this disclosure is a value obtained by measuring each thermoplastic resin using the melt mass flow rate value in accordance with JIS-K7210.

[0021] <Carbon Nanotubes (B)> Carbon nanotubes (B) satisfy the following (1) and (2): (1) The total metal content is 10,000 ppm or less, and (2) In powder X-ray diffraction analysis, the half-width of the diffraction peak of the (002) plane is 2.0 to 6.0°.

[0022] Carbon nanotubes (B) have a structure similar to a graphene sheet rolled into a cylinder, and are called single-walled carbon nanotubes (SWCNTs) when they are single-walled, and multi-walled carbon nanotubes (MWCNTs) when they are multi-walled, and individual carbon nanotubes can be confirmed using an electron microscope, etc. Carbon nanotubes form primary aggregates of carbon nanotube fibers, becoming entangled or forming bundle-like primary aggregates, but the primary aggregates can also aggregate to form secondary or higher aggregates.

[0023] The carbon nanotubes (B) may be single-walled carbon nanotubes, multi-walled carbon nanotubes wound with two or more layers, or a mixture of these, but multi-walled carbon nanotubes are preferred from the standpoints of cost and strength. Also, carbon nanotubes whose sidewalls have an amorphous structure instead of a graphite structure may be used.

[0024] Carbon nanotubes (B) can generally be produced by laser ablation, arc discharge, chemical vapor deposition (CVD), combustion, etc., but any method may be used. In particular, CVD is a method that allows for inexpensive mass production of carbon nanotubes by contacting catalyst fine particles, typically comprising a carrier such as silica, alumina, magnesium oxide, titanium oxide, silicate, diatomaceous earth, alumina silica, silica titania, or zeolite, carrying a metal catalyst such as iron, cobalt, or nickel, with a carbon-containing gas as a raw material at a high temperature of typically 400 to 1000° C., and is preferred for the carbon nanotubes used in some embodiments of the present disclosure.

[0025] [Metal Content] The carbon nanotubes (B) have a total metal content of 10,000 ppm or less, based on the mass of the carbon nanotubes (B). The metal content in the carbon nanotubes (B) is preferably 500 to 10,000 ppm, more preferably 500 to 7,500 ppm, and even more preferably 500 to 7,200 ppm. Examples of metals include iron, cobalt, aluminum, and molybdenum. Each metal atom in the carbon nanotubes (B) can exist as a magnetic substance such as a metal or alloy, or as a non-magnetic substance such as an oxide or carbide. Having the total metal content of the carbon nanotubes (B) within the above range increases the purity of the carbon nanotubes (B), resulting in excellent electrical conductivity and dispersibility of the carbon nanotubes (B) in the thermoplastic resin composition. For example, the metal content in the carbon nanotubes (B) may be 100 to 10,000 ppm, 500 to 7,500 ppm, 500 to 7,200 ppm, or 1,000 to 5,000 ppm.

[0026] The content of metal components in carbon nanotubes can be analyzed using inductively coupled plasma (ICP). Specifically, the analysis can be performed according to the method described in the Examples.

[0027] When a catalyst containing iron atoms is used, the carbon nanotubes (B) may contain iron. When the carbon nanotubes (B) contain iron, the iron atom content in the carbon nanotubes (B) is preferably 10 to 5,000 ppm, more preferably 10 to 4,000 ppm, and even more preferably 10 to 3,000 ppm. Having the iron atom content in the carbon nanotubes (B) within this range suppresses deterioration of the carbon nanotubes due to the purification treatment and improves the dispersibility of the carbon nanotubes (B) in the thermoplastic resin composition. For example, the iron atom content in the carbon nanotubes (B) may be 10 to 5,000 ppm, 50 to 4,500 ppm, 50 to 4,000 ppm, 100 to 3,500 ppm, or 1,000 to 3,000 ppm. The iron atoms in the carbon nanotubes (B) can exist as a magnetic substance such as a metal or alloy, or as a non-magnetic substance such as an oxide or carbide. When the iron atom content of the carbon nanotubes (B) is within the above range, the conductivity of the carbon nanotubes (B) is increased, and corrosion of metals in contact with the carbon nanotubes (B) can be suppressed.

[0028] Methods for adjusting the amount of iron atoms contained in carbon nanotubes (B) to fall within the above range include a method of increasing the yield of carbon nanotubes (B) per mass of catalyst particles in the production process of carbon nanotubes (B), a method of using catalyst particles that do not contain iron atoms, a method of reducing the proportion of iron atoms in the catalyst particles, and a method of reducing the amount of iron atoms mixed in in the production process of carbon nanotubes (B). Furthermore, iron atoms may be removed by known methods such as acid treatment, graphitization treatment, and chlorination treatment, which will be described later.

[0029] When a catalyst containing cobalt atoms is used, the carbon nanotubes (B) may contain cobalt atoms. When the carbon nanotubes (B) contain cobalt atoms, the content of cobalt atoms in the carbon nanotubes (B) is preferably 10 to 1,000 ppm, more preferably 10 to 800 ppm, even more preferably 20 to 700 ppm, and even more preferably 10 to 600 ppm. When the content of cobalt atoms in the carbon nanotubes (B) is within this range, deterioration of the carbon nanotubes due to the purification treatment is suppressed, and the dispersibility of the carbon nanotubes (B) in the thermoplastic resin composition is excellent. The cobalt atoms in the carbon nanotubes (B) can exist as a magnetic material such as a metal or alloy, or as a non-magnetic material such as an oxide or carbide. For example, the content of cobalt atoms in the carbon nanotubes (B) may be 10 to 1,000 ppm, 30 to 800 ppm, 50 to 600 ppm, or 100 to 500 ppm.

[0030] When catalyst particles containing cobalt atoms are used in the production process of carbon nanotubes (B), the cobalt atom content of the carbon nanotubes (B) within the above range allows for production without reducing the productivity of the carbon nanotubes (B). Furthermore, by having the cobalt atom content within the above range, the amount of cobalt atoms acting as a non-magnetic substance is reduced, allowing for a reduction in the volume resistivity of the resin molded product. Methods for adjusting the amount of cobalt atoms contained in the carbon nanotubes within the above range include a method for increasing the carbon nanotube yield per mass of catalyst particles in the carbon nanotube production process, and a method for reducing the proportion of cobalt atoms in the catalyst particles. Furthermore, the cobalt atoms may be removed by known methods such as acid treatment, graphitization, or chlorination, which will be described later.

[0031] Metal components contained in carbon nanotubes may be removed by known methods to the extent that the effects of the present invention are not impaired. Examples include acid treatment, graphitization treatment, and chlorination treatment. When removing metal components by acid treatment, the acid used may be any acid that can dissolve the metal components contained in the carbon nanotubes. For example, an inorganic acid or a carboxylic acid is preferred, and among inorganic acids, hydrochloric acid, sulfuric acid, and nitric acid are particularly preferred. The acid treatment of carbon nanotubes is preferably carried out in a liquid phase, and it is more preferred to disperse and / or mix the carbon nanotubes in the liquid phase. After the acid treatment, the carbon nanotubes are preferably washed with water and dried.

[0032] The graphitization treatment of the carbon nanotubes can be carried out, for example, by heating the carbon nanotubes at 1500 to 3500° C. in an inert atmosphere with an oxygen concentration of 0.1% or less.

[0033] The chlorination treatment of carbon nanotubes can be carried out, for example, by introducing chlorine gas into an inert atmosphere with an oxygen concentration of 0.1% or less and heating the carbon nanotubes at 800 to 2000°C.

[0034] As a method for removing metal components contained in carbon nanotubes, acid treatment or graphitization treatment is preferred from the viewpoint of cost.

[0035] [Fulfillment Width at Half Maximum of X-ray Diffraction Peak] The full width at half maximum of the diffraction peak of the (002) plane of the carbon nanotubes (B) is 2.0 to 6.0°. Preferably, this full width at half maximum is 2.0 to 5.0°, more preferably 2.0 to 3.5°. By keeping the full width at half maximum within the above range, the thermoplastic resin composition exhibits good dispersibility of the carbon nanotubes. For example, this full width at half maximum may be 2.0 to 6.0°, 2.1 to 5.8°, 2.3 to 5.0°, or 2.5 to 3.2°. If the full width at half maximum is less than 2.0°, the number of carbon nanotubes per unit mass is reduced due to the large number of carbon nanotubes, which can lead to variations in conductivity when dispersed in a resin. On the other hand, if the full width at half maximum is greater than 6.0°, the number of carbon nanotubes is reduced and approaches single-walled, resulting in a large number of carbon nanotubes per unit mass, which can easily cause aggregation of carbon nanotubes and result in poor dispersibility. Therefore, by setting the half width to 2.0 to 6.0°, both uniform dispersion and uniform conductivity of the carbon nanotubes can be achieved.

[0036] The (002) plane of carbon nanotube (B) is detected at a 2θ of 25°±2°, and varies depending on the distance between the carbon hexagonal mesh planes. The higher the peak position, the closer the distance between the carbon hexagonal mesh planes, indicating a higher degree of graphitic regularity in the structure. Furthermore, the sharper the peak (the smaller the half-width), the larger the crystallite size and the more developed the crystal structure.

[0037] The half-width of carbon nanotubes (B) is determined as follows. First, carbon nanotubes (B) are packed into a specified sample holder so that the surface is flat, and then placed in a powder X-ray diffraction analyzer. Measurements are performed by varying the irradiation angle of the X-ray source from 5° to 80°. For example, CuKα radiation is used as the X-ray source. The step width is 0.010°, and the measurement time is 1.0 second. Carbon nanotubes (B) can be evaluated by reading the diffraction angle 2θ at which a peak appears. In graphite, a peak is typically detected at 2θ around 26°, which is known to be a peak due to interlayer diffraction. Since carbon nanotubes (B) also have a graphite structure, a peak due to graphite interlayer diffraction is detected in this vicinity. However, because carbon nanotubes have a cylindrical structure, this value differs from that of graphite. The appearance of a peak at 2θ of 25°±2° indicates that the composition contains a multilayer structure rather than a single layer. The peak appearing at this position is a peak due to interlayer diffraction of the multilayer structure, making it possible to determine the number of layers of the carbon nanotubes (B). Since single-walled carbon nanotubes do not have one layer, a peak does not appear at 25°±2° if there are only single-walled carbon nanotubes. However, even single-walled carbon nanotubes are not 100% single-walled carbon nanotubes, and if multi-walled carbon nanotubes or the like are mixed in, a peak may appear at 2θ of 25°±2°.

[0038] In some embodiments of the present disclosure, the carbon nanotube (B) exhibits a peak at 2θ of 25°±2°. The layer structure can also be analyzed from the half-width of the 25°±2° peak detected by powder X-ray diffraction analysis. That is, the smaller the half-width of this peak, the greater the number of layers of the carbon nanotube (B). Conversely, the larger the half-width of this peak, the fewer the number of layers of the carbon nanotube.

[0039] In some embodiments of the present disclosure, when the carbon nanotube (B) is subjected to powder X-ray diffraction analysis, a peak exists at a diffraction angle 2θ=25°±2°, and the half width of the peak of the (002) plane is 2.0 to 6.0°.

[0040] [Ash Content] The ash content of carbon nanotubes is a non-combustible component containing metal components and the like. The ash content of carbon nanotubes (B) is preferably 0.001 to 1.0 mass%, more preferably 0.01 to 0.9 mass%, and even more preferably 0.1 to 0.8 mass%. The ash content of carbon nanotubes can be calculated according to formula (i) by measuring the ashing residue after firing at 900°C for 1 hour in air: Ash content of carbon nanotubes (mass%) = Ash content mass (g) after firing / Mass of carbon nanotubes (g) before firing × 100 Formula (i) Having an ash content within the above range is preferable because it further improves conductivity and dispersibility.

[0041] [Volume Resistivity] The volume resistivity of the carbon nanotube (B) is 1.0 × 10 －３ ~3.0 x 10 －２ Preferably, the resistance is Ω cm, and 1.0×10 －３ ~2.5 x 10 －２ Ω cm is more preferable, and 1.0×10 －３ ~2.0 x 10 －２ It is more preferable that the volume resistivity is Ω cm. When the volume resistivity of the carbon nanotubes (B) is within the above range, the conductivity of the resin molded body becomes better. The volume resistivity of the carbon nanotubes (B) can be measured and determined using a powder resistivity measuring device (Loresta GP Powder Resistivity Measuring System MCP-PD-51, manufactured by Nitto Seiko Analytech Co., Ltd.).

[0042] [BET specific surface area] The BET specific surface area of ​​the carbon nanotubes (B) is 200 to 600 m ２ / g, and 200 to 500m ２ / g, and more preferably 200 to 400m ２ / g is even more preferable. The BET specific surface area of ​​carbon nanotubes can be calculated by the BET method using nitrogen adsorption measurements. There is often a correlation between the specific surface area of ​​carbon nanotubes and the average outer diameter of carbon nanotubes; the smaller the specific surface area, the larger the outer diameter of the carbon nanotubes, and the fewer the number of carbon nanotubes per mass. On the other hand, the larger the specific surface area of ​​carbon nanotubes, the smaller the outer diameter of the carbon nanotubes, and the more the number of carbon nanotubes per mass. When the specific surface area of ​​the carbon nanotubes is within the above range, the number of carbon nanotubes per mass is such that a conductive network can be efficiently formed, and the carbon nanotubes have a cohesive force that makes them easily dispersible, so that a good conductive network can be formed and the conductivity is higher.

[0043] [G / D ratio in Raman spectrum] Carbon nanotubes (B) have a G / D ratio of 1560 to 1600 cm in Raman spectrum. －１ The maximum peak intensity in the range of 1310 to 1350 cm －１ When the maximum peak intensity within this range is defined as D, the G / D ratio is preferably 0.5 to 5.0, more preferably 0.5 to 4.0, and even more preferably 0.5 to 3.0. When the G / D ratio of the carbon nanotubes is within the above range, the electrical conductivity and uniformity of the resin molded body can be improved.

[0044] The G / D ratio was measured by placing a powder sample in a microscopic laser Raman spectrophotometer (JASCO Corporation, NRS-3100) and using a laser wavelength of 532 nm. －１ The G band from the graphite structure near 1350 cm －１ It can be calculated from the integral value of the D band peak derived from structural defects near 1590 cm －１ The Raman shift observed around 1350 cm is called the G band derived from graphite. －１ The Raman shift observed around this band is called the D band, which is derived from defects in amorphous carbon and graphite. The higher the G / D ratio of a carbon nanotube, the higher its degree of graphitization, crystallinity, and purity.

[0045] [Average Diameter] The carbon nanotubes (B) preferably have an average diameter of 5 to 20 nm, more preferably 8 to 15 nm. When the average diameter of the carbon nanotubes is within the above range, the specific surface area is large, a conductive network is easily formed, and the carbon nanotubes are easily dispersed into aggregates, resulting in good conductivity and dispersibility, and thus excellent conductivity and uniformity of the resin molded product, which is preferable.

[0046] The average diameter of the carbon nanotubes (B) can be determined by image analysis. For example, the carbon nanotubes are observed using a scanning electron microscope (JSM-6700M, manufactured by JEOL Ltd.) at an acceleration voltage of 5 kV, and an image (1024 x 1280 pixels) is taken at 50,000 magnifications. Next, the minor axis length of each of 20 random carbon nanotubes in the image is measured, and the number average of the obtained minor axis lengths can be used as the average diameter of the carbon nanotubes.

[0047] <Other Components> In some embodiments of the present disclosure, the resin molded product and the thermoplastic resin composition may contain, as needed, an oxidation stabilizer, a weathering stabilizer, an antistatic agent, a dye, a pigment, a dispersant, a coupling agent, a crystal nucleating agent, a resin filler, or the like.

[0048] <Production Method> In some embodiments of the present disclosure, the method for producing a thermoplastic resin composition is not particularly limited. For example, a thermoplastic resin (A), carbon nanotubes (B), and, if necessary, additives are added and mixed in a Henschel mixer, tumbler, disperser, or the like, and then mixed or melt-kneaded in a batch mixer such as a kneader, roll mill, super mixer, Henschel mixer, Schuggie mixer, vertical granulator, high-speed mixer, Farmatrix, ball mill, steel mill, sand mill, vibration mill, attritor, or Banbury mixer, a twin-screw extruder, a single-screw extruder, or a rotor-type twin-screw kneader, to obtain a resin composition in the form of pellets, powder, granules, beads, or the like. In some embodiments of the present disclosure, a twin-screw extruder is preferably used for melt-kneading. In this case, the melt-kneading conditions (temperature, screw rotation speed, etc.) are not particularly limited.

[0049] In some embodiments of the present disclosure, the thermoplastic resin composition may be a compound having a relatively low concentration of carbon nanotubes (B) and used for molding as is without diluting with thermoplastic resin (A), or may be a masterbatch containing a relatively high concentration of carbon nanotubes (B) and used by diluting with thermoplastic resin (A) during molding. Both the compound and the masterbatch are preferably in the form of pellets for easy handling.

[0050] In the thermoplastic resin composition, the content of the carbon nanotubes (B) is preferably 0.1 to 30 parts by mass per 100 parts by mass of the thermoplastic resin (A).

[0051] In the case of a compound, the content of the carbon nanotubes (B) is preferably 0.1 to 25 parts by mass, more preferably 0.1 to 12 parts by mass, even more preferably 0.5 to 12 parts by mass, particularly preferably 1.0 to 12 parts by mass, and most preferably 2.0 to 10 parts by mass, relative to 100 parts by mass of the thermoplastic resin (A). A content of the carbon nanotubes (B) of 25 parts by mass or less is preferred because it is possible to suppress re-aggregation of the carbon nanotubes and improve dispersibility.

[0052] In the case of a compound, the content of the carbon nanotubes (B) is preferably 0.1 to 20 mass%, more preferably 0.1 to 10 mass%, even more preferably 0.5 to 10 mass%, particularly preferably 1.0 to 10 mass%, and most preferably 2.0 to 10 mass%, based on the mass of the compound (100 mass%). The thermoplastic resin composition according to some embodiments of the present disclosure allows the carbon nanotubes to be uniformly dispersed in the thermoplastic resin even at a high concentration, such as 10 mass% or more.

[0053] In the case of a compound, the metal content in the compound is preferably 3,000 ppm or less, more preferably 2,500 ppm or less.

[0054] In the case of the masterbatch, the content of the carbon nanotubes (B) is preferably 12 to 30 parts by mass, and more preferably 12 to 25 parts by mass, per 100 parts by mass of the thermoplastic resin (A). When the content of the carbon nanotubes (B) is 30 parts by mass or less, re-aggregation of the carbon nanotubes can be suppressed, resulting in better dispersibility.

[0055] In the case of the masterbatch, the content of the carbon nanotubes (B) is preferably 10 to 23 mass %, more preferably 10 to 20 mass %, based on the mass of the masterbatch (100 mass %).

[0056] In the case of a masterbatch, the metal content in the masterbatch is preferably 30,000 ppm or less, more preferably 20,000 ppm or less, even more preferably 15,000 ppm or less, and particularly preferably 3,000 ppm or less.

[0057] The metal content in the resin composition after diluting the masterbatch with the thermoplastic resin (A) during molding is preferably 3,000 ppm or less, and more preferably 2,500 ppm or less.

[0058] In some embodiments, the carbon nanotubes (B) preferably have a total metal content of 500 to 7200 ppm in (1) and a half-width of the diffraction peak of the (002) plane of 2.0 to 3.5° in powder X-ray diffraction analysis in (2). In this case, the carbon nanotubes (B) preferably have an iron content of 50 to 4500 ppm and a cobalt content of 20 to 700 ppm. Furthermore, the carbon nanotubes (B) preferably have an ash content of 0.001 to 1.0 when heated at 900°C for 1 hour and a volume resistivity of 1.0 x 10 －３ ~3.0 x 10 －２ Ω cm, and the BET specific surface area is 200 to 600 m ２ / g. Furthermore, in this case, the thermoplastic resin (A) preferably contains at least one selected from the group consisting of polyolefin resins such as polyethylene resins, polypropylene resins, and cycloolefin resins (COP), acrylonitrile-butadiene-styrene copolymer resins, polycarbonate resins, polyamide resins, and polyester-based resins. By providing these components, it is possible to suppress the aggregation of carbon nanotubes, and to obtain a resin molded product that has excellent uniformity of carbon nanotubes and high electrical conductivity when formed into a resin molded product. Furthermore, it is possible to suppress the deterioration of the thermoplastic resin composition over time, and to obtain a thermoplastic resin composition that suppresses thermal deterioration even in a high-temperature atmosphere.

[0059] Some embodiments of the present disclosure can provide a thermoplastic resin composition comprising a thermoplastic resin (A) and carbon nanotubes (B), the composition comprising 0.1 to 30 parts by mass of the carbon nanotubes (B) per 100 parts by mass of the thermoplastic resin (A), the carbon nanotubes (B) having a half-width of the (002) plane of 2.0 to 6.0° in powder X-ray diffraction analysis, and a total metal content of 3,000 ppm or less. This thermoplastic resin composition can be obtained, for example, by melt-kneading the thermoplastic resin (A) with the carbon nanotubes (B) having (1) a total metal content of 10,000 ppm or less and (2) a half-width of the (002) plane of 2.0 to 6.0° in powder X-ray diffraction analysis.

[0060] Resin Molded Article In some embodiments of the present disclosure, a resin molded article is formed using the thermoplastic resin composition of the above embodiment. Applications are not particularly limited, and the resin molded article can be used for conductive trays. It can also be used as a protective material for electronic components, such as packaging bags for electronic components. It can also be used for personal computer bodies and built-in electronic components, external hard disks, home appliances, automobile parts, electromagnetic wave absorbers, and the like.

[0061] The resin molded body can be produced by melt-kneading and molding a thermoplastic resin composition containing carbon nanotubes (B) and a thermoplastic resin (A). Specifically, the compound or master batch and diluted resin are melt-mixed in a molding machine typically set at 50°C to 350°C, and then the molded body is formed and cooled. The molding machine temperature is not critical as long as it is a temperature at which the thermoplastic resin (A) softens, but is preferably at least 30°C higher than the softening point of the thermoplastic resin (A), which is the main component.

[0062] The resin molded body can be obtained in the form of a plate, rod, fiber, tube, pipe, bottle, film, sheet, or the like. In some embodiments of the present disclosure, the thermoplastic resin composition has excellent dispersibility of carbon nanotubes, so that a resin molded body with excellent uniformity can be obtained even if the thickness is 2 mm or more. The thickness of the resin molded body is not particularly limited and can be set according to the application, but the thickness of the resin molded body is preferably 0.1 to 100 mm, and more preferably 0.1 to 80 mm.

[0063] Examples of the molding method that can be used include extrusion molding, injection molding, blow molding, compression molding, transfer molding, film molding such as T-die molding and inflation molding, calendar molding, and spinning. Extrusion molding, injection molding, blow molding, T-die molding, and inflation molding are preferred, and extrusion molding and injection molding are particularly preferred.

[0064] The metal content in the resin molded product is preferably 3,000 ppm or less, and more preferably 2,500 ppm or less. The metal content in the resin molded product can be calculated from the metal content of the thermoplastic resin composition, and in the case of a compound, it can be determined from the metal content in the compound, or in the case of a masterbatch, it can be determined from the total metal content of the masterbatch and the diluted resin.

[0065] The present disclosure will be described in more detail below with reference to examples, but the following examples do not limit the present disclosure in any way. In the examples, "parts" represents "parts by mass" and "%" represents "% by mass." The respective measurement methods are as follows.

[0066] <Measurement of total metal content, iron (Fe) atom content, and cobalt (Co) atom content in carbon nanotubes> Carbon nanotubes were subjected to acid decomposition with 70% nitric acid using a microwave sample pretreatment device (Milestone General, ETHOS1) to extract the metals (iron, cobalt, etc.) contained in the carbon nanotubes. Analysis was then performed using a multi-type ICP optical emission spectrometer (Agilent, 720-ES) to calculate the total metal content, iron atom content, and cobalt atom content of the carbon nanotubes.

[0067] <Powder X-ray diffraction analysis of carbon nanotubes> A carbon nanotube was placed in the central recess of an aluminum sample plate (outer diameter φ46 mm, thickness 3 mm, sample portion φ26.5 mm, thickness 2 mm) and flattened using a glass slide. Then, a medicine paper was placed on the surface on which the sample was placed, and a load of 1 ton was applied to the surface on which the aluminum high-sheet packing was placed to flatten it. The medicine paper and aluminum high-sheet packing were then removed to obtain a sample for powder X-ray diffraction analysis of the carbon nanotube. The sample for powder X-ray diffraction analysis of the carbon nanotube was then placed in an X-ray diffractometer (Ultima 2100, manufactured by Rigaku Corporation) and operated from 15° to 35° for analysis. Sampling was performed every 0.02°, and the scan speed was 2° / min. The voltage was 40 kV, the current was 40 mA, and the X-ray source was CuKα radiation. The plots of the (002) plane of the carbon nanotube appearing at a diffraction angle of 2θ = 25° ± 2° were each calculated by a simple moving average of 11 points, and the half width of the peak was taken as the half width of the carbon nanotube. The baseline was a line connecting the plots at 2θ = 16° and 2θ = 34°.

[0068] <Ash Content of Carbon Nanotubes> The ash content of the carbon nanotubes (B) was calculated based on formula (i) after 1.0 g of the carbon nanotubes was placed in a porcelain crucible, heated in a furnace at 900°C for 1 hour, and cooled: ash content of carbon nanotubes (mass %) = ash content (g) after firing / mass of carbon nanotubes (g) before firing × 100 (formula (i)).

[0069] <Volume Resistivity of Carbon Nanotubes> Using a powder resistivity measurement device (Loresta-GP Powder Resistivity Measurement System MCP-PD-51, manufactured by Nitto Seiko Analytech Co., Ltd.), the volume resistivity [Ω cm] of the conductive powder under various pressures was measured using a powder probe unit (four-point ring electrode, electrode spacing 5.0 mm, electrode radius 1.0 mm, sample radius 12.5 mm) with a sample mass of 1.2 g and an applied voltage limiter of 90 V. ３ The volume resistivity of the carbon nanotubes at the density was calculated.

[0070] <BET Specific Surface Area of ​​Carbon Nanotubes> 0.03 g of carbon nanotubes was weighed using an electronic balance (MSA225S100DI, manufactured by Sartorius) and then dried for 15 minutes at 110° C. while degassing. Thereafter, the BET specific surface area of ​​the carbon nanotubes was measured using a fully automatic specific surface area measuring device (HM-model 1208, manufactured by MOUNTECH).

[0071] <Raman Spectroscopic Analysis of Carbon Nanotubes> Carbon nanotubes were placed in a microscopic laser Raman spectrophotometer (JASCO Corporation, NRS-3100), and measurements were performed using a laser wavelength of 532 nm. The measurement conditions were: acquisition time 60 seconds, number of integrations 2, neutral density filter 10%, objective lens magnification 20x, confocus hole 500, slit width 100 μm, and measurement wavelength 100 to 3000 cm －１ The carbon nanotubes for measurement were collected on a slide glass and flattened using a spatula. Among the peaks obtained, the spectrum showed a peak between 1560 and 1600 cm －１ The maximum peak intensity is G within the range of 1310 to 1350 cm －１ The maximum peak intensity within this range was defined as D, and the G / D ratio was defined as the G / D ratio of the carbon nanotube.

[0072] <MFR (Melt Mass Flow Rate) of Thermoplastic Resin (A)> The MFR of the thermoplastic resin (A) was measured in accordance with JIS-K7210 using a melt indexer manufactured by Toyo Seiki Seisakusho, Ltd. The measurement was performed under the following conditions: a temperature of 190°C and a load of 2.16 kgf for polyethylene resins, a temperature of 230°C and a load of 2.16 kgf for polyolefin resins other than polyethylene resins, a temperature of 220°C and a load of 10 kgf for acrylonitrile-butadiene-styrene copolymer resins, a temperature of 280°C and a load of 1.2 kgf for polycarbonate resins, a temperature of 240°C and a load of 2.16 kgf for polyamide resins, and a temperature of 280°C and a load of 1.2 kgf for polyester resins.

[0073] The materials used in the examples are as follows: <Thermoplastic resin (A)> (A-1) Kernel KJ-640T (manufactured by Japan Polyethylene Corporation, polyethylene resin, MFR: 30 g / 10 min) (A-2) Novatec MA1B (manufactured by Japan Polypropylene Corporation, polypropylene resin, MFR: 21 g / 10 min) (A-3) Stylac ABS191 (manufactured by Asahi Kasei Chemicals Corporation, ABS resin, MFR: 26 g / 10 min) (A-4) Iupilon H-3000 (manufactured by Mitsubishi Engineering Plastics Corporation, polycarbonate resin, MFR: 35 g / 10 min) (A-5) Amilan CM1017 (manufactured by Toray Industries, Inc., polyamide resin, MFR: 35 g / 10 min) (A-6) Duranex 700FP (manufactured by Polyplastics Co., Ltd., polyester resin, MFR: 30 g / 10 min) (A-7) DURACON M90-44 (manufactured by Polyplastics Co., Ltd., polyacetal resin, MFR: 9 g / 10 min (measurement conditions: 190°C, 2.16 kgf)) (A-8) ZEONOR 1020R (manufactured by Zeon Corporation, cycloolefin resin, MFR: 20 g / 10 min (measurement conditions: 280°C, 2.16 kgf))

[0074] <Carbon nanotubes> (B-1) Carbon nanotubes of Production Example 1 (B-2) Carbon nanotubes of Production Example 2 (B-3) Carbon nanotubes of Production Example 3 (B-4) Carbon nanotubes of Production Example 4 (B-5) Carbon nanotubes of Production Example 5 (B-6) Carbon nanotubes of Production Example 6 (B-7) Carbon nanotubes of Production Example 7 (B-8) Carbon nanotubes of Production Example 8 (B-9) Carbon nanotubes of Production Example 9 (B'-1) Carbon nanotubes of Production Example 10 (B'-2) Carbon nanotubes of Production Example 11 (B'-3) Carbon nanotubes of Production Example 12

[0075] (Production Example 1: B-1) <Catalyst for synthesizing carbon nanotubes (B-1)> 20 g of cobalt hydroxide and 43 g of iron (III) nitrate nonahydrate were placed in a heat-resistant container and dried for 2 hours at an ambient temperature of 170±5°C using an electric oven to obtain a cobalt composition and an iron composition. 69 g of magnesium acetate tetrahydrate and 4.1 g of manganese (II) carbonate were placed in a heat-resistant container and dried for 2 hours at an ambient temperature of 170±5°C using an electric oven to evaporate the water. 29 g of the cobalt composition and iron composition were then mixed with 2.0 g of Aerosil (AEOSIL (registered trademark) 200, manufactured by Nippon Aerosil Co., Ltd.) as a second support to obtain a catalyst precursor for synthesizing carbon nanotubes (B-1). The catalyst precursor for synthesizing carbon nanotubes (B-1) was then transferred to a heat-resistant container and baked in a muffle furnace (FO510, manufactured by Yamato Scientific Co., Ltd.) in an air atmosphere at 450±5°C for 30 minutes, and then pulverized in a mortar to obtain a catalyst for synthesizing carbon nanotubes (B-1).

[0076] Synthesis of Carbon Nanotubes (B-1) A quartz glass heat-resistant dish, onto which 2 g of the carbon nanotube (B-1) synthesis catalyst had been sprayed, was placed in the center of a horizontal reaction tube with an internal volume of 10 L, which could be pressurized and heated with an external heater. The reaction tube was evacuated while nitrogen gas was injected, and the air in the reaction tube was replaced with nitrogen gas, adjusting the atmosphere in the horizontal reaction tube to an oxygen concentration of 1% by volume or less. The horizontal reaction tube was then heated with an external heater until the central temperature reached 680°C. After reaching 680°C, propane gas was introduced into the reaction tube as a carbon source at a flow rate of 2 L per minute, and the reaction was carried out for 1 hour. After the reaction was completed, the gas in the reaction tube was replaced with nitrogen gas, and the reaction tube was cooled to 100°C or less and removed, yielding a carbon nanotube (B-1) precursor. 1000 g of carbon nanotube (B-1) precursor was weighed into a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was evacuated while maintaining positive pressure. After the oxygen concentration in the furnace became 0.1% or less, the temperature in the furnace was raised to 3000°C over 30 hours and then maintained at 3000°C for 30 minutes. Then, heating in the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B-1).

[0077] (Production Example 2: B-2) <Synthesis of Carbon Nanotubes (B-2)> 1000 g of the carbon nanotube (B-1) precursor from Production Example 1 was weighed into a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was evacuated while maintaining positive pressure. After the oxygen concentration in the furnace became 0.1% or less, the temperature in the furnace was raised to 3000°C over 30 hours, and then maintained at 3000°C for 10 minutes. Thereafter, heating in the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B-2).

[0078] (Production Example 3: B-3) <Synthesis of Carbon Nanotubes (B-3)> 1000 g of the carbon nanotube (B-1) precursor from Production Example 1 was weighed into a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was evacuated while maintaining positive pressure. After the oxygen concentration in the furnace became 0.1% or less, the temperature in the furnace was raised to 3000°C over 30 hours, and then maintained at 3000°C for 1 hour. Thereafter, heating in the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B-3).

[0079] (Production Example 4: B-4) <Synthesis of Carbon Nanotubes (B-4)> 10 kg of the carbon nanotube (B-1) precursor from Production Example 1 was weighed into a 120 L heat-resistant container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. The reactor was then evacuated while nitrogen gas was injected, and the air in the reactor was replaced with nitrogen gas. The horizontal reactor was heated until the ambient temperature reached 700°C. After reaching 700°C, ethylene gas as a hydrocarbon was introduced into the reactor at a flow rate of 2 L per minute, and a catalytic reaction was carried out for 15 minutes. After the reaction was completed, the gas in the reactor was replaced with nitrogen gas, and the reactor was cooled to a temperature of 100°C or less and removed to obtain a carbon nanotube (B-4) precursor. 1000 g of the carbon nanotube (B-4) precursor was weighed into a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-4) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was discharged while maintaining a positive pressure. After the oxygen concentration in the furnace reached 0.1% or less, the temperature in the furnace was raised to 3000°C over 30 hours, and then maintained at 3000°C for 30 minutes. Then, heating in the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B-4).

[0080] (Production Example 5: B-5) <Synthesis of Carbon Nanotubes (B-5)> 1000 g of the carbon nanotube (B-1) precursor from Production Example 1 was weighed into a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was evacuated while maintaining positive pressure. After the oxygen concentration in the furnace became 0.1% or less, the temperature in the furnace was raised to 3000°C over 30 hours, and then maintained at 3000°C for 1 hour and 20 minutes. Heating of the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B-5).

[0081] (Production Example 6: B-6) <Synthesis of Carbon Nanotubes (B-6)> 10 kg of the carbon nanotube (B-1) precursor from Production Example 1 was weighed into a 120 L heat-resistant container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was discharged while maintaining positive pressure. After the oxygen concentration in the furnace became 0.1% or less, the furnace was heated to 1600°C over 30 hours. While maintaining the furnace temperature at 1600°C, chlorine gas was introduced at a rate of 50 L / min for 50 hours. Nitrogen gas was then introduced at 50 L / min, and the furnace was cooled while maintaining positive pressure, to obtain carbon nanotubes (B-6).

[0082] (Production Example 7: B-7) <Synthesis of Carbon Nanotubes (B-7)> 10 g of the carbon nanotube (B-1) precursor of Production Example 1 was weighed into a 1 L glass container, and 500 g of 60% nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, followed by thorough stirring using a stirrer. The mixture was then thoroughly diluted with ion-exchanged water and subjected to vacuum filtration using a membrane filter. After repeating the dilution and filtration operations, the carbon nanotubes were transferred to a PTFE tray and dried in an oven at 140°C to obtain carbon nanotubes (B-7).

[0083] (Production Example 8: B-8) <Synthesis of Carbon Nanotubes (B-8)> 1000 g of the carbon nanotube (B-1) precursor from Production Example 1 was weighed into a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was evacuated while maintaining positive pressure. After the oxygen concentration in the furnace became 0.1% or less, the temperature in the furnace was increased to 2900°C over 30 hours, and then maintained at 2900°C for 2 hours. Heating of the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B-8).

[0084] (Production Example 9: B-9) <Synthesis of Carbon Nanotubes (B-9)> 1000 g of the carbon nanotube (B-1) precursor from Production Example 1 was weighed into a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was evacuated while maintaining positive pressure. After the oxygen concentration in the furnace became 0.1% or less, the temperature in the furnace was raised to 2900°C over 30 hours, and then maintained at 2900°C for 1 hour and 40 minutes. Heating of the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B-9).

[0085] (Production Example 10: B'-1) The carbon nanotube (B-1) precursor of Production Example 1 was designated as carbon nanotube (B'-1).

[0086] (Production Example 11: B'-2) <Catalyst for synthesizing carbon nanotubes (B'-2)> 1,000 parts by mass of magnesium acetate tetrahydrate was weighed into a heat-resistant container and dried in an electric oven at an ambient temperature of 170±5°C for 6 hours. The resulting mixture was then pulverized using a pulverizer (Sample Mill KIIW-I, manufactured by Dalton Co., Ltd.) equipped with a 1 mm screen to obtain a dried and pulverized magnesium acetate product. 45.8 parts of the dried and pulverized magnesium acetate product, 8.1 parts of manganese carbonate, 1.0 part of silicon oxide (SiO2, manufactured by Nippon Aerosil Co., Ltd.: AEROSIL (registered trademark) 200), and 200 parts of steel beads (bead diameter 2.0 mmφ) were placed in an SM sample bottle (manufactured by Sansho Co., Ltd.), and the mixture was pulverized and mixed for 30 minutes using a paint conditioner manufactured by Red Devil Co., Ltd. Thereafter, a stainless steel sieve was used to separate the pulverized and mixed powder from steel beads (bead diameter 2.0 mmφ), yielding a catalyst support for carbon nanotube (B'-2) synthesis. Then, 20 parts by mass of cobalt hydroxide and 43 parts by mass of iron (III) nitrate nonahydrate were weighed into a heat-resistant container and dried at an ambient temperature of 170±5°C for 2 hours to obtain a cobalt composition and an iron composition. Further, 54.9 parts by mass of the catalyst support for carbon nanotube (B'-2) synthesis and 29 parts by mass of the cobalt composition and iron composition were charged into a pulverizer (Wonder Crusher WC-3, manufactured by Osaka Chemical Co., Ltd.), a standard lid was attached, the speed dial was adjusted to 2, and the mixture was pulverized and mixed for 30 seconds to obtain a catalyst precursor for carbon nanotube synthesis (B'-2). The catalyst precursor for synthesizing carbon nanotubes (B'-2) was transferred to a heat-resistant container and baked in a muffle furnace (FO510, manufactured by Yamato Scientific Co., Ltd.) in an air atmosphere at 450±5°C for 30 minutes, and then crushed in a mortar to obtain a catalyst for synthesizing carbon nanotubes (B'-2).

[0087] Synthesis of Carbon Nanotubes (B'-2) A quartz glass heat-resistant dish, onto which 1 g of carbon nanotube (B'-2) synthesis catalyst was sprayed, was placed in the center of a 10 L horizontal reactor tube that could be pressurized and heated with an external heater. The reactor tube was evacuated while nitrogen gas was injected, and the air inside the reactor tube was replaced with nitrogen gas. The horizontal reactor tube was heated until the ambient temperature reached 680°C. After reaching 680°C, ethylene gas was introduced into the reactor tube at a flow rate of 2 L / min, and the catalytic reaction was carried out for 7 minutes. After the reaction was completed, the gas inside the reactor tube was replaced with nitrogen gas, and the reactor tube was cooled to below 100°C and removed, yielding a carbon nanotube (B'-2) precursor. 1000 g of the carbon nanotube (B'-2) precursor was weighed into a heat-resistant carbon container. The heat-resistant carbon container containing the carbon nanotube (B'-2) precursor was then placed in a furnace. The furnace was then evacuated to a pressure of 1 Torr (133 Pa) or less, and a carbon heater was energized to heat the interior of the furnace to 1000°C. Next, argon gas was introduced into the furnace, adjusting the pressure inside the furnace to 70 Torr (9.33 kPa), and then 1 L / min of argon gas was introduced into the furnace. Then, in addition to the argon gas, chlorine gas was introduced, adjusting the pressure inside the furnace to 90 Torr (11.99 kPa). After this pressure was reached, 0.3 L / min of chlorine gas was introduced into the furnace. After maintaining this state for 1 hour, the power was stopped, and the introduction of argon gas and chlorine gas was stopped, followed by vacuum cooling. Finally, vacuum cooling was performed at a pressure of 1 Torr (133 Pa) or less for 12 hours. After confirming that the furnace had cooled to room temperature, nitrogen gas was introduced into the furnace until atmospheric pressure was reached, and the heat-resistant container was removed to obtain carbon nanotubes (B'-2).

[0088] (Production Example 12: B'-3) <Synthesis of Carbon Nanotubes (B'-3)> 1000 g of the carbon nanotube (B-1) precursor from Production Example 1 was weighed out and placed in a 7 L heat-resistant carbon container, and the heat-resistant container containing the carbon nanotube (B-1) precursor was placed in a furnace. Nitrogen gas was then introduced into the furnace, and the air in the furnace was evacuated while maintaining positive pressure. After the oxygen concentration in the furnace reached 0.1% or less, the temperature in the furnace was raised to 3000°C over 30 hours, and then maintained at 3000°C for 2 hours and 30 minutes. Heating of the furnace was stopped, and the sample was cooled to obtain carbon nanotubes (B'-3).

[0089]

[0090] (Example 1) (Production of Thermoplastic Resin Composition) Thermoplastic resin (A-1) 98.5% by mass and carbon nanotubes (B-1) 1.5% by mass were mixed and melt-kneaded, and the mixture was extruded at 230°C using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) and granulated to obtain a thermoplastic resin composition.

[0091] Examples 2 to 4, 9 to 15, 18 to 19, 21 to 22 Thermoplastic resin compositions were obtained in the same manner as in Example 1, except that the materials and blending amounts (mass %) were changed to those shown in Tables 2 and 3, respectively.

[0092] Example 5 Thermoplastic resin (A-3) 95% by mass and carbon nanotubes (B-1) 5% by mass were mixed and melt-kneaded, and the mixture was extruded at 250°C using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) and granulated to obtain a thermoplastic resin composition.

[0093] Examples 6 to 8, 20, and 23 Thermoplastic resin compositions were obtained in the same manner as in Example 5, except that the materials and blending amounts (mass %) were changed to those shown in Tables 2 and 3, respectively.

[0094] (Example 16) (Production of Masterbatch) 80% by mass of thermoplastic resin (A-1) and 20% by mass of carbon nanotubes (B-1) were mixed and melt-kneaded, and the mixture was extruded at 230°C using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) and granulated to obtain a thermoplastic resin composition (masterbatch).

[0095] Example 17 Thermoplastic resin (A-2) 80% by mass and carbon nanotubes (B-1) 20% by mass were mixed and melt-kneaded, and the mixture was extruded at 230°C using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) and granulated to obtain a thermoplastic resin composition (masterbatch).

[0096] Comparative Example 1 Thermoplastic resin (A-1) 94 mass % and carbon nanotubes (B'-1) 6 mass % were mixed and melt-kneaded, and the mixture was extruded at 230°C using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) and granulated to obtain a thermoplastic resin composition.

[0097] Comparative Examples 2 and 3 Thermoplastic resin compositions and resin molded articles were obtained in the same manner as in Comparative Example 1, except that the materials and blending amounts (mass %) were changed to those shown in Tables 1 and 2, respectively.

[0098] <<Measurement and Evaluation of Physical Properties of Thermoplastic Resin Composition>> The physical properties of the obtained thermoplastic resin compositions were measured and evaluated by the following methods. The results are shown in Tables 2 and 3. For the masterbatches of Examples 16 and 17, the same thermoplastic resin (A) as used in the production of the masterbatches was used as a diluent resin, and a resin molded article was produced using an injection molding machine in the blending amounts (mass%) shown in Tables 2 and 3.

[0099] [Production of Molded Article Z1] The thermoplastic resin composition was molded using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) with a cylinder set temperature of 220°C and a mold temperature of 40°C to obtain a molded article Z1 having a length of 90 mm, a width of 110 mm, and a thickness of 3 mm. For the thermoplastic resin compositions of Examples 5 to 8, 20, and 23, molded articles Z1 were produced using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) with a cylinder set temperature of 250°C and a mold temperature of 80°C.

[0100] [Production of Molded Product Z2] A 100 μm thick sheet (molded product Z2) was produced using a T-die molding machine at a temperature 30° C. higher than the melting point of the thermoplastic resin (A) that was the main component used in the thermoplastic resin composition. When the thermoplastic resin (A) was an amorphous thermoplastic resin (resins A-3, A-4, and A-8), a 100 μm thick sheet (molded product Z2) was produced using a T-die molding machine at a temperature 130° C. higher than the glass transition temperature.

[0101] [Production of Molded Product Z3] The thermoplastic resin composition was molded using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) with a cylinder set temperature of 220°C and a mold temperature of 40°C to obtain a molded product Z3 having a length of 60 mm, a width of 60 mm, and a thickness of 2 mm. The thermoplastic resin compositions of Examples 5 to 8, 20, and 23 were molded using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) with a cylinder set temperature of 250°C and a mold temperature of 80°C to produce molded product Z3.

[0102] [Production of Molded Product Z4] Using the thermoplastic resin composition, a molded product Z4 of type A1 dumbbell-shaped test piece in accordance with JIS-K7139:2019 was produced.

[0103] (Total Metal Content) The thermoplastic resin composition was subjected to acid decomposition with 70% nitric acid using a microwave sample pretreatment device (ETHOS1, manufactured by Milestone General Co., Ltd.), and the metals contained in the thermoplastic resin composition were extracted. Thereafter, analysis was performed using a multi-type ICP optical emission spectrometer (720-ES, manufactured by Agilent Corporation), and the total metal content (ppm) of the thermoplastic resin composition was calculated.

[0104] (Electrical Conductivity) Electrical conductivity was evaluated by surface resistivity. Using the obtained molded body (molded body Z1) having a length of 90 mm, a width of 110 mm, and a thickness of 3 mm, the surface resistivity was measured at any five points using a Loresta-GP MCP-T610 resistivity meter (compliant with JIS-K7194, four-terminal four-probe constant current application method) manufactured by Nitto Seiko Analytech Co., Ltd., and the average value was calculated. It can be said that the smaller the surface resistivity, the higher the electrical conductivity. The evaluation criteria are as follows. [Evaluation Criteria] ⊚: The surface resistivity of the molded body is 1.0 x 10 ３ Ω / □ or less, which is excellent for practical use. ○: The surface resistivity of the molded product is 1.0 × 10 ３ Ω / □, more than 1.0 x 10 ５ Ω / □ or less, which is excellent for practical use. △: The surface resistivity of the molded product is 1.0 × 10 ５ Ω / □, more than 1.0 x 10 ７ Ω / □ or less and practically usable ×: The surface resistivity of the molded product is 1.0 × 10 ７ Exceeds Ω / □ and is not practical

[0105] (Uniformity) The uniformity of CNTs within the molded body was evaluated by surface smoothness, in-plane variation, and molding shrinkage. Good surface smoothness means that the resin has good fluidity even when affected by the thickening effect of CNTs, and the CNTs are uniformly dispersed without uneven dispersion, resulting in a molded body with a uniform surface without surface variation. The more uniform the concentration on the molded body surface, the smaller the difference in conductivity, and the better the uniformity of the CNT concentration on the molded body surface. The molding shrinkage represents the uniformity of the CNT concentration throughout the molded body; the smaller the difference in molding shrinkage, the more uniformly the CNTs are dispersed throughout the molded body. Furthermore, a good molding shrinkage is most desirable, as it indicates the uniformity of the entire molded body.

[0106] <Surface Smoothness> Surface smoothness was evaluated by the maximum height Sz of the sheet surface. Using the obtained 100 μm thick sheet (molded body Z2), the maximum height Sz (μm) was measured using a Talysurf CCI MP-HS manufactured by Taylor / Hobson, with a measurement length of 2.5 mm x 2.5 mm and a robust Gaussian filter of 0.08 mm. The smaller the Sz, the more uniformly the CNTs are dispersed in the thermoplastic resin composition. [Evaluation Criteria] ◎: Sz of the molded body is 2.0 μm or less, and is particularly excellent for practical use. ○: Sz of the molded body is more than 2.0 μm and less than 3.0 μm, and is excellent for practical use. △: Sz of the molded body is more than 3.0 μm and less than 5.0 μm, and is usable for practical use. ×: Sz of the molded body is more than 5.0 μm, and is not usable for practical use.

[0107] <In-plane Variation> Using the obtained molded body (molded body Z1) having a length of 90 mm, a width of 110 mm, and a thickness of 3 mm, the surface resistivity was measured at any five points using a Hiresta manufactured by Mitsubishi Chemical Corporation, and the maximum / minimum value (X) was calculated from the maximum and minimum values ​​to evaluate. The evaluation criteria are as follows. The smaller the value of the maximum / minimum value (X), the smaller the in-plane variation. [Evaluation Criteria] ⊚: The maximum / minimum value (X) of the surface resistivity of the molded body is 1≦X<5, and is particularly excellent for practical use. ○: The maximum / minimum value (X) of the surface resistivity of the molded body is 5≦X<10, and is excellent for practical use. △: The maximum / minimum value (X) of the surface resistivity of the molded body is 10≦X<100, and is usable for practical use. ×: The maximum / minimum value (X) of the surface resistivity of the molded body is 100≦X, and is not usable for practical use.

[0108] <Molding shrinkage> For the obtained molded body (molded body Z3) having a length of 60 mm, a width of 60 mm and a thickness of 2 mm, the molding shrinkage in the direction parallel to the flow direction of the thermoplastic resin composition (MD) and the molding shrinkage in the direction perpendicular to the flow direction (TD) were measured, and the molding shrinkage ratio was calculated as molding shrinkage (TD) / molding shrinkage (MD). The smaller the molding shrinkage ratio, the better the uniformity of the CNTs throughout the molded body. [Evaluation criteria] ◎: The molding shrinkage ratio of the molded body is 1.5 or less, and is particularly excellent for practical use. ○: The molding shrinkage ratio of the molded body is greater than 1.5 and less than 2.5, and is excellent for practical use. △: The molding shrinkage ratio of the molded body is greater than 2.5 and less than 3.5, and is usable for practical use. ×: The molding shrinkage ratio of the molded body is greater than 3.5, and is not usable for practical use.

[0109] (Thermal Stability over Time) The thermal stability over time was evaluated by thermal degradation resistance. The obtained dumbbell-shaped test pieces (molded body Z4) of each Example, etc. were aged under the following conditions: (1) 24 hours in a 23°C atmosphere (before thermal aging), and (2) 120 hours in a 130°C atmosphere (test pieces after thermal aging), and the tensile strength was measured in accordance with JIS-K7161-1:2014. The tensile strength retention rate was calculated from the obtained tensile strength according to the following formula. It can be said that the higher the tensile strength retention rate, the higher the thermal stability over time. Tensile strength retention (%) = Tensile strength (MPa) of test piece after heat aging / Tensile strength (MPa) of test piece before heat aging × 100 [Evaluation criteria] ◎: The tensile strength retention of the molded product is 95% or more, and is particularly excellent for practical use. ○: The tensile strength retention of the molded product is 90% or more and less than 95%, and is excellent for practical use. △: The tensile strength retention of the molded product is 80% or more and less than 90%, and is usable for practical use. ×: The tensile strength retention of the molded product is less than 80%, and is not usable for practical use.

[0110]

[0111]

[0112] From the results shown in Tables 2 and 3, it was confirmed that the use of the thermoplastic resin compositions of each Example suppresses the aggregation of carbon nanotubes, and when formed into a resin molded product, it is possible to obtain a resin molded product having excellent uniformity of carbon nanotubes and high conductivity. Furthermore, it was confirmed that the deterioration of the thermoplastic resin composition over time due to heat is eliminated, and a thermoplastic resin composition in which thermal deterioration is suppressed even in a high-temperature atmosphere can be obtained.

[0113] Although the present invention has been described with reference to the above several embodiments, the present invention is not limited to the above several embodiments. Various modifications can be made to the configuration and details of the present invention within the scope of the present invention. This disclosure is related to the subject matter described in Japanese Patent Application No. 2024-111663, filed on July 11, 2024, the entire disclosure of which is incorporated herein by reference.

Claims

1. A thermoplastic resin composition comprising a thermoplastic resin (A) and carbon nanotubes (B), wherein the carbon nanotubes (B) satisfy the following requirements (1) and (2): (1) The total metal content is 10,000 ppm or less. (2) In powder X-ray diffraction analysis, the half-width of the diffraction peak of the (002) plane is 2.0 to 6.0°.

2. The thermoplastic resin composition according to claim 1, wherein the carbon nanotubes (B) have an ash content of 0.001 to 1.0 mass % when heated at 900°C for 1 hour.

3. The thermoplastic resin composition according to claim 1, wherein the iron content of the carbon nanotubes (B) is 10 to 5,000 ppm.

4. Carbon nanotubes (B) have a volume resistivity of 1.0 x 10 －３ ~3.0 x 10 －２ The thermoplastic resin composition according to claim 1, wherein the modulus is Ω·cm.

5. Carbon nanotubes (B) have a BET specific surface area of ​​200 to 600 m ２ The thermoplastic resin composition according to claim 1, wherein the modulus of elasticity is 1 / g.

6. The thermoplastic resin composition according to claim 1, wherein the cobalt content of the carbon nanotubes (B) is 10 to 1,000 ppm.

7. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin (A) comprises at least one resin selected from the group consisting of polyolefin resins, acrylonitrile-butadiene-styrene copolymer resins, polycarbonate resins, polyamide resins, and polyester resins.

8. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin (A) comprises at least one resin selected from the group consisting of polyethylene resin, polypropylene resin, and cycloolefin resin.

9. The thermoplastic resin composition according to claim 1, wherein the total metal content of the thermoplastic resin composition is 3,000 ppm or less.

10. The thermoplastic resin composition according to claim 1, which contains 0.1 to 30 parts by mass of carbon nanotubes (B) per 100 parts by mass of the thermoplastic resin (A).

11. A thermoplastic resin composition comprising a thermoplastic resin (A) and carbon nanotubes (B), wherein the carbon nanotubes (B) are contained in an amount of 0.1 to 30 parts by mass per 100 parts by mass of the thermoplastic resin (A), wherein the carbon nanotubes (B) have a half-width of a diffraction peak of the (002) plane of 2.0 to 6.0° in powder X-ray diffraction analysis, and the total metal content of the thermoplastic resin composition is 3,000 ppm or less.

12. The thermoplastic resin composition according to any one of claims 1 to 10, wherein in (1) above, the total metal content is 500 to 7200 ppm, and in (2) above, the half-value width of the diffraction peak of the (002) plane in powder X-ray diffraction analysis is 2.0 to 3.5°.

13. The thermoplastic resin composition according to claim 11, wherein the iron content of said carbon nanotubes (B) is 50 to 4500 ppm, and the cobalt content of said carbon nanotubes (B) is 20 to 700 ppm.

14. A resin molded article formed using the thermoplastic resin composition according to any one of claims 1 to 11.

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