Resin composite, resin composite production method, and resin composition production method

Abstract

The present invention provides: a resin composite having excellent conductivity and also excellent mechanical strength; a resin composite production method; and a resin composition production method.　A resin composite according to the present disclosure has a surface resistance of 1×10-5 to 1×10 Ω / sq, and the tensile strength based on JIS K7161 as measured for a type-A1 dumbbell-shaped tensile test specimen in compliance with JIS K7139 is 50 to 500 MPa.

Description

Resin composite, method for manufacturing a resin composite, and method for manufacturing a resin composition

[0001] This disclosure relates to resin composites, methods for producing resin composites, and methods for producing resin compositions.

[0002] The use of carbon nanotubes in combination with resins has been considered for some time. For example, Patent Document 1 proposes a carbon nanotube-containing composition containing carbon nanotubes (a) and a syndiotactic poly(methacrylate ester) (b) having a syndiotacticity of 65%rr or higher in triple-representation (%rr). Patent Document 1 states that the carbon nanotube-containing composition has excellent conductivity.

[0003] Japanese Patent Publication No. 2008-156478

[0004] In the embodiment of Patent Document 1, the surface resistance value is 1.5 × 10 8 Ω, or 8.0 × 10 9 A carbon nanotube-containing composition of Ω had been disclosed. However, there was a need to further improve conductivity. Furthermore, no resin composite possessing both excellent conductivity and excellent mechanical strength was known. Therefore, this disclosure aims to provide a resin composite with excellent conductivity and excellent mechanical strength, a method for manufacturing the resin composite, and a method for manufacturing the resin composition.

[0005] As a result of diligent research, the inventors discovered a resin composite that exhibits excellent conductivity and mechanical strength, thus completing the present invention.

[0006] In other words, the present invention relates, for example, to the following [1] to

[10] : [1] Surface resistance is 1 × 10 -5[1] A resin composite having a tensile strength of 50 to 500 MPa, measured on a dumbbell-shaped tensile test specimen of type A1 conforming to JIS K7139, with a tensile strength of ~1 × 10 Ω / sq. [2] The resin composite according to [1], wherein the resin content is 80 to 97% by mass in 100% by mass of the resin composite. [3] The resin composite according to [1] or [2], wherein the carbon nanotubes are contained in 3 to 20% by mass in 100% by mass of the resin composite. [4] A method for producing a resin composite containing resin and carbon nanotubes, comprising the steps of: preparing a resin solution and a carbon nanotube forest formed on a substrate; immersing the carbon nanotube forest in the resin solution; peeling the resin-impregnated carbon nanotubes from the substrate after immersion; and kneading the resin-impregnated carbon nanotubes with the resin. [5] Use as a masterbatch of the resin composite described in any of [1] to [3], or a resin composite manufactured by the manufacturing method described in [4]. [6] A method for producing a resin composition, comprising the step of diluting the resin composite described in any of [1] to [3], or a resin composite manufactured by the manufacturing method described in [4], with at least one of a resin and a solvent. [7] The method for producing a resin composition according to [6], wherein the dilution step is a step of kneading the resin composite and the resin. [8] A resin composition obtained by diluting the resin composite described in any of [1] to [3], or a resin composite manufactured by the manufacturing method described in [4], with at least one of a resin and a solvent.

[0007] [9] A resin composite comprising a resin and carbon nanotubes, wherein the resin composite comprises 3 to 20% by mass of carbon nanotubes in 100% by mass of the resin composite.

[10] The resin composite according to [9], wherein the tensile strength measured on a dumbbell-shaped tensile test specimen of type A1 conforming to JIS K7139, prepared using the resin composite, is 1.5 to 6 times the tensile strength measured on the components constituting the resin composite excluding carbon nanotubes.

[0008] According to the present invention, it is possible to provide a resin composite that has excellent conductivity and also excellent mechanical strength.

[0009] The upper and / or lower limits of the numerical ranges described herein can be arbitrarily combined to define a preferred range. For example, the upper and lower limits of the numerical ranges can be arbitrarily combined to define a preferred range, the upper limits of the numerical ranges can be arbitrarily combined to define a preferred range, and the lower limits of the numerical ranges can be arbitrarily combined to define a preferred range.

[0010] Throughout this specification, singular expressions should be understood to include the concept of their plural form unless otherwise specified. Therefore, singular articles (for example, "a," "an," and "the" in English) should be understood to include the concept of their plural form unless otherwise specified.

[0011] In this specification, unless otherwise specified, each component may be used independently, individually, or in combination of two or more.

[0012] In this specification, "carbon nanotube" refers to a cylindrical structure made of graphene sheets. Carbon nanotubes are sometimes referred to as "CNTs".

[0013] In this specification, "single-walled carbon nanotube" refers to a carbon nanotube having one layer of tube structure. "Multi-walled carbon nanotube" refers to a carbon nanotube having two or more layers of tube structure, preferably 2 to 20 layers, more preferably 3 to 15 layers.

[0014] <Resin Composite> The resin composite of this disclosure has a surface resistance of 1 × 10 -5 The tensile strength measured on a dumbbell-shaped tensile test specimen of type A1 conforming to JIS K7139, with a resistance of ~1 × 10 Ω / sq and a tensile strength of 50 to 500 MPa according to JIS K7161, is specified. The resin composite is a composite containing resin. Hereinafter, in this specification, "tensile strength measured on a dumbbell-shaped tensile test specimen of type A1 conforming to JIS K7139, according to JIS K7161" will also be referred to as "tensile strength".

[0015] The resin composite has a surface resistance of 1 × 10⁻⁶ -5 ~1 × 10Ω / sq, but 1 × 10 -5 It may be up to 7Ω / sq, 1 × 10 -4 It may be up to 5Ω / sq, 5 × 10 -4 It may also be ~3Ω / sq. Surface resistance may be expressed as Ω / sq, Ω / □, Ω, etc., but these units are synonymous.

[0016] The resin composite has a tensile strength of 50 to 500 MPa, but may also be 60 to 450 MPa, 100 to 400 MPa, or 130 to 350 MPa. From another viewpoint, if the resin composite contains resin and carbon nanotubes, the tensile strength may be 1.5 to 6 times, 1.8 to 5 times, or 2.0 to 4.5 times when compared to the tensile strength of the resin composite excluding the carbon nanotubes, for example, the resin constituting the resin composite (polyamide 6 (PA6) in the example) alone. The tensile strength can be measured by manufacturing the dumbbell-shaped tensile test specimen using the resin composite or the components constituting the resin composite excluding the carbon nanotubes.

[0017] The resin composite may have a tensile modulus (also referred to as tensile modulus) of 1500 to 10000 MPa, 2000 to 8000 MPa, or 3000 to 7500 MPa, measured on a dumbbell-shaped tensile test specimen of type A1 conforming to JIS K7139, based on JIS K7161. Furthermore, from another perspective, if the resin composite contains resin and carbon nanotubes, the tensile modulus may be 1.7 to 6 times, 2.0 to 5.2 times, or 2.2 to 4.7 times when compared to the tensile modulus of the resin composite excluding the carbon nanotubes, for example, the resin constituting the resin composite (polyamide 6 (PA6) in the example) alone. The tensile modulus can be measured by manufacturing the dumbbell-shaped tensile test specimen using the resin composite or the components constituting the resin composite excluding the carbon nanotubes.

[0018] The resin composite typically contains 50% by mass or more of resin, preferably 80 to 97% by mass, more preferably 83 to 96.5% by mass, and even more preferably 86 to 96% by mass. Within this range, it is preferable to obtain a resin composite that achieves both excellent conductivity and mechanical strength.

[0019] The resin composite preferably contains a resin and a component that can impart conductivity and mechanical strength. For example, the resin composite preferably contains a resin and carbon nanotubes. The inventors have found that a resin composite containing a resin and carbon nanotubes, and containing carbon nanotubes at a high concentration, exhibits excellent conductivity and mechanical strength. Therefore, another embodiment of the resin composite of this disclosure is a resin composite containing a resin and carbon nanotubes, wherein the resin composite contains 3 to 20% by mass of carbon nanotubes in 100% by mass of the resin composite.

[0020] On the other hand, one preferred embodiment of the resin composite is one in which it substantially does not contain carbon black. Another preferred embodiment of the resin composite is one in which it substantially does not contain graphene. Another preferred embodiment of the resin composite is one in which it substantially does not contain graphite. Furthermore, one preferred embodiment of the resin composite is one in which it substantially does not contain metal particles.

[0021] In the present invention, "substantially free of a certain substance" means that the content of that substance in the resin composite is less than 1% by mass, preferably less than 0.5% by mass, and more preferably less than 0.3% by mass. There is no particular lower limit, and it may be below the detection limit, for example, 0% by mass.

[0022] Thermoplastic resins are typically used as the resin. Examples of thermoplastic resins include polyolefins, polyvinyl chloride, polyvinylidene chloride, styrene resins, (meth)acrylic resins, polyesters, polyamides, thermoplastic polyimides, polycarbonates, polyacetals, polyphenylene ethers, and polyphenylene sulfides.

[0023] Examples of polyolefins include polyethylene such as high-density polyethylene, medium-density polyethylene, high-pressure low-density polyethylene, and linear low-density polyethylene, as well as ethylene-vinyl acetate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, polypropylene, polybutene, polymethylpentene, and ethylene-propylene copolymers.

[0024] Examples of styrene-based resins include polystyrene, styrene-maleic anhydride copolymer, AS resin, and ABS resin.

[0025] Examples of polyesters include polyethylene terephthalate and polybutylene terephthalate.

[0026] Examples of polyamides include aliphatic polyamides and semi-aromatic polyamides. Examples of aliphatic polyamides include polyamide 6, polyamide 66, polyamide 610, polyamide 11, and polyamide 12. Examples of semi-aromatic polyamides include terephthalic acid-based polyamides such as polyamide 6T and polyamide 9T.

[0027] The thermoplastic resin is preferably a resin that is soluble in a solvent.

[0028] The carbon nanotubes (CNTs) may be single-walled carbon nanotubes or multi-walled carbon nanotubes with two or more layers. Preferably, the CNTs are multi-walled carbon nanotubes. The number of layers in the multi-walled carbon nanotubes is not particularly limited, but is preferably 2 to 20 layers.

[0029] The average length of the CNTs is preferably 10 to 1000 μm, more preferably 30 to 800 μm, even more preferably 50 to 500 μm, and particularly preferably 100 to 300 μm. Note that this average length of the CNTs refers to the average length of the CNTs used in the production of the resin composite, i.e., the average length of the CNTs as raw material. The average length of the CNTs can be adjusted, for example, by adjusting the time spent in the CVD method described later, i.e., the CNT growth time.

[0030] The average diameter of the CNT is preferably 1 to 50 nm, more preferably 3 to 30 nm, and even more preferably 5 to 15 nm. The average diameter of the CNT can be adjusted, for example, by adjusting the thickness of the catalyst layer and the type of catalyst described later.

[0031] The average length and average diameter of the CNT are measured by a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Specifically, 10 images of the CNT are obtained using an SEM or a TEM or the like. For each of the 10 images, 10 length measurement points are arbitrarily selected and measured, and the lengths of a total of 100 points are measured. Then, the average length of the CNT is determined by calculating the arithmetic mean of the measured values of the lengths of the 100 points. Also, for each of the 10 images, 10 diameter measurement points are arbitrarily selected and measured, and the diameters of a total of 100 points are measured. Then, the average diameter of the CNT is determined by calculating the arithmetic mean of the measured values of the diameters of the 100 points.

[0032] The carbon purity of the CNT is preferably 95.0 to 99.999%. The lower limit value of the carbon purity of the CNT is preferably 96.0%, more preferably 97.0%, even more preferably 98.0%, still more preferably 99.0%, and particularly preferably 99.8%. The upper limit value of the carbon purity of the CNT may be, for example, 99.99% or 99.9%. The carbon purity of the CNT can be determined, for example, by elemental analysis using fluorescent X-rays.

[0033] The crystallinity of the CNT can be evaluated, for example, using Raman spectroscopy. In the evaluation of crystallinity by Raman spectroscopy, the value of the D / G ratio is used as an index. The D / G ratio is the ratio of the peak intensity of the D band appearing around 1360 cm -1 to the peak intensity of the G band appearing around 1580 cm -1 in the Raman spectrum measured by Raman spectroscopy. The smaller the value of the D / G ratio, the higher the crystallinity of the carbon nanotube. The D / G ratio in the CNT is preferably 0.5 to 1.0, more preferably 0.6 to 0.8.

[0034] The carbon purity and crystallinity of the CNTs can be adjusted, for example, by adjusting the thickness of the buffer layer in the catalyst substrate, the type of material used in the buffer layer, the thickness of the catalyst layer, the type of catalyst, the type and flow rate of the raw material gas in the CVD method, and the temperature and pressure in the reaction chamber, as described later.

[0035] CNTs can be manufactured using conventionally known methods. For example, CNTs can be manufactured using chemical vapor deposition (CVD) methods such as thermochemical vapor deposition (thermal CVD), plasma CVD, laser ablation, arc discharge, or combustion. Among the CVD methods, thermal CVD is preferred.

[0036] The CVD method involves placing a catalyst substrate, which has a catalyst layer provided on a substrate, into a reaction chamber, supplying a raw material gas to the reaction chamber, and growing CNTs as a CNT forest on the surface of the catalyst layer. A CNT forest refers to an aggregate of multiple CNTs provided on a substrate and oriented perpendicular to the surface of the substrate. In a CNT forest, multiple CNTs stand upright on the substrate. The average length and average diameter of the CNTs in the CNT forest are, for example, the same as the average length and average diameter of the CNTs described above. CNT powder is obtained by scraping the CNT forest from the substrate. CNT powder means powder containing multiple CNTs.

[0037] Examples of substrates include silicon substrates, alumina substrates, magnesium oxide substrates, glass substrates, sapphire substrates, and stainless steel substrates.

[0038] The catalyst layer can be formed, for example, by attaching catalyst particles to a substrate by sputtering. Examples of the catalyst include metals, specifically, iron (Fe), nickel (Ni), cobalt (Co), molybdenum (Mo), gold (Au), and alloys containing at least one metal selected from the group consisting of these. Examples of the alloy include iron alloys, nickel alloys, and cobalt alloys. The catalyst may be a metal precursor such as a metal oxide and a metal compound. Examples of the metal oxide include iron oxide, nickel oxide, and cobalt oxide. Examples of the metal compound include iron chloride. When using a precursor, it is necessary to convert it to a metal before performing the CVD method, such as by heating the precursor.

[0039] The catalyst substrate may further include a buffer layer between the substrate and the catalyst layer. The buffer layer can be formed, for example, by sputtering. Examples of the material used for the buffer layer include silica (SiO2), alumina (Al2O3), silicon nitride (SiN), zinc oxide (ZnO), copper oxide (Cu2O), and nickel oxide (NiO).

[0040] Sputtering for forming the catalyst layer and sputtering for forming the buffer layer can be performed using known apparatuses and conditions according to the sputtering target. The pressure condition for performing sputtering is, for example, about 0.001 to 100 Pa.

[0041] As the raw material gas, a raw material gas containing carbon can be used. For example, hydrocarbons, sulfur-containing organic gases, phosphorus-containing organic gases, carbon monoxide, and alcohols can be mentioned. Examples of hydrocarbons include alkane compounds such as methane and ethane, alkene compounds such as ethylene and butadiene, alkyne compounds such as acetylene, aryl hydrocarbon compounds such as benzene, toluene, and styrene, aromatic hydrocarbons having a condensed ring such as indene, naphthalene, and phenanthrene, cycloalkane compounds such as cyclopropane and cyclohexane, cycloolefin compounds such as cyclopentene, and alicyclic hydrocarbon compounds having a condensed ring such as steroid. Examples of alcohols include methanol and ethanol. From the viewpoint of the carbon purity of the obtained CNT, the raw material gas is preferably a hydrocarbon.

[0042] A carrier gas, which is a gas for transporting the raw material gas, may be supplied to the reaction chamber together with the raw material gas. Examples of the carrier gas include helium, neon, argon, nitrogen, and hydrogen.

[0043] The temperature in the reaction chamber in the CVD method is, for example, 550 to 900 °C from the viewpoints of the growth rate of CNT and the carbon purity of the obtained CNT.

[0044] The pressure in the reaction chamber in the CVD method may be normal pressure, reduced pressure, or increased pressure.

[0045] The amount of CNT contained in the resin composite is 3 to 20% by mass, preferably 3.5 to 17% by mass, and more preferably 4 to 14% by mass. Within the above range, the content of CNT is large, which is preferable because the conductivity and mechanical properties of the resin composite are particularly excellent.

[0046] In the resin composite, the mass ratio of CNT to resin (carbon nanotube: resin) is preferably 1:5 to 1:25, and more preferably 1:7 to 1:20, from the viewpoints of the conductivity and mechanical properties of the obtained resin composite.

[0047] The resin composite comprises a resin, preferably a thermoplastic resin, and preferably CNTs, but may also contain other components. Examples of other components include various additives. Examples of other components include color inhibitors, antioxidants, defoamers, pigments, dyes, and ultraviolet absorbers. There may be one or more of these other components. When the resin composite contains other components, the amount of these other components is, for example, 0.01 to 5% by mass, preferably 0.05 to 3% by mass, and more preferably 0.1 to 1% by mass.

[0048] Because resin composites possess excellent conductivity and mechanical properties, they can be used in a wide variety of applications. For example, they can be used in various applications such as daily necessities, household goods, and industrial products. Resin composites can be used as parts or components in various items such as home appliances, communication equipment, electrical and electronic equipment, automobiles and other vehicles, ships, aircraft, building materials, civil engineering materials, agricultural materials, power tools, and food containers. There are no particular restrictions on the shape of resin composites when used in various applications, but examples include the shapes of films, sheets, fibers, and various parts or components.

[0049] The resin composite may be used for various applications by diluting it with other resins. In other words, this disclosure includes the use of the resin composite as a masterbatch.

[0050] The resin composites of this disclosure can be obtained by kneading a resin with components that can impart conductivity and mechanical strength. Resin composites containing resin and carbon nanotubes can be obtained by the manufacturing method described later. In the manufacturing method described later, carbon nanotubes can be uniformly dispersed in the resin, making it possible to produce resin composites with excellent conductivity and mechanical properties.

[0051] <Method for Manufacturing Resin Composites> As an example of a method for manufacturing resin composites, the case in which the resin composite contains resin and carbon nanotubes will be described. The method for manufacturing resin composites according to this disclosure includes the steps of: preparing a resin solution and a carbon nanotube forest formed on a substrate; immersing the carbon nanotube forest in the resin solution; peeling the resin-impregnated carbon nanotubes from the substrate after immersion; and kneading the resin-impregnated carbon nanotubes with the resin.

[0052] A resin solution can be prepared by dissolving the aforementioned resin in a solvent. For example, a resin solution can be obtained by adding the resin to a solvent, stirring, and dissolving the resin. There are no particular restrictions on the solvent; any solvent capable of dissolving the resin used should be employed. For example, if the resin is a polyamide, 2,2,2-trifluoroethanol, hexafluoroisopropanol, dimethyl sulfoxide, formamide, dimethylacetamide, etc., can be used as the solvent. It is preferable to use a solvent that can be easily removed by heating, reduced pressure, etc.

[0053] The amount of resin contained in the resin solution is, for example, 5 to 30% by mass, preferably 6 to 27% by mass, and more preferably 8 to 24% by mass, based on 100% by mass of the solution.

[0054] A carbon nanotube forest (CNT forest) can be prepared by the method described above. As mentioned above, a CNT forest can be prepared as a CNT forest formed on a substrate.

[0055] The process of immersing the carbon nanotube forest in a resin solution can be carried out, for example, by the following method. In this specification, the process of immersing the carbon nanotube forest in a resin solution is also referred to as the immersion process.

[0056] In the immersion process, the amount of resin solution used is not particularly limited, as long as it is sufficient to adequately encapsulate the carbon nanotube forest formed on the substrate. It is preferable to adjust the amount of resin solution used, the immersion time, etc., so that the mass ratio (resin:carbon nanotube) of resin to carbon nanotube is preferably 5:95 to 25:75, more preferably 7:93 to 23:77, and even more preferably 9:91 to 21:79 in the resin-impregnated carbon nanotubes peeled off from the substrate after immersion.

[0057] From the viewpoint of ensuring that the carbon nanotube forest formed on the substrate is sufficiently impregnated with resin, it is preferable to immerse the carbon nanotube forest in the resin solution from the carbon nanotube forest side. In other words, it is preferable to hold the CNT forest formed on the substrate with the substrate on the upper side and the CNT forest on the lower side, and immerse the CNT forest in the resin solution while maintaining that state.

[0058] The immersion time is, for example, 5 seconds to 10 hours, 10 seconds to 5 hours, 20 seconds to 1 hour, or 25 seconds to 5 minutes. The temperature during immersion is, for example, room temperature (15 to 40°C). The immersion process may be performed once or multiple times (for example, two or three times).

[0059] In the immersion process, the carbon nanotubes are impregnated with resin. After the immersion process, the resin-impregnated carbon nanotubes are peeled off the substrate of the carbon nanotube forest. This peeling process is also called the peeling process. Through the peeling process, resin-impregnated carbon nanotubes (resin-impregnated carbon nanotubes) can be obtained.

[0060] A step to remove the solvent constituting the resin solution may be included between the immersion step and the peeling step. A drying step is one such step to remove the solvent. For example, after the immersion step, the carbon nanotube forest substrate may be air-dried, heat-dried, or dried under reduced pressure. By including a drying step, it is easy to prevent solvent from remaining in the resin composite.

[0061] A method for producing a resin composite according to the present disclosure comprises a step of kneading resin-impregnated carbon nanotubes with a resin. This step is also referred to as the kneading step. In the kneading step, the resin-impregnated carbon nanotubes and the resin are kneaded, for example, using an extruder. Examples of extruders include single-screw extruders and twin-screw extruders. In one preferred embodiment, the resin kneaded with the resin-impregnated carbon nanotubes in the kneading step is the same type of resin as the resin constituting the resin-impregnated carbon nanotubes.

[0062] From the viewpoint of facilitating the kneading process, the method for manufacturing the resin composite preferably includes a step of pulverizing the resin-impregnated carbon nanotubes obtained in the peeling step (also referred to as the pulverization step). The resin-impregnated carbon nanotubes can be easily processed into a powder. In the pulverization step, it is preferable to pulverize the resin-impregnated carbon nanotubes using a force mill for plastics or the like. Since the surface of the resin-impregnated carbon nanotubes is considered to be covered with resin, it is possible to easily pulverize them into a powder.

[0063] A resin composite can be obtained by kneading resin-impregnated carbon nanotubes with resin during the kneading process.

[0064] The mixing conditions should be set appropriately according to the resin. Specifically, the melting point, glass transition temperature, etc. of the resin should be taken into consideration, and the conditions should be set appropriately based on general conditions for that resin.

[0065] <Use as a Masterbatch, Resin Composition, Method for Manufacturing a Resin Composition> As described above, since the resin composite has excellent conductivity and mechanical properties, it may be used as a material itself and molded (e.g., secondary molding) for various applications. The resin composite can also be used as a masterbatch. As a masterbatch, a composition, specifically a resin composition, can be obtained by diluting the resin composite with a resin. Another method of use is to dilute the resin composite with a solvent to obtain a resin composition, specifically a dispersion, containing, for example, CNTs, a resin, and a solvent. As a masterbatch, a resin composition, containing, for example, CNTs, a resin, and a solvent, can be obtained by diluting the resin composite with a resin and a solvent. That is, the present disclosure includes a method for manufacturing a resin composition, which includes a step of diluting the resin composite with at least one of a resin and a solvent. In one preferred embodiment, the dilution step is a step of kneading the resin composite with the resin. In another preferred embodiment, the dilution step is a step of mixing the resin composite with the solvent. In yet another preferred embodiment, the dilution step is a step of mixing the resin composite with the resin and a solvent. Furthermore, this disclosure includes resin compositions obtained by diluting a resin composite with at least one of a resin and a solvent.

[0066] There are no particular restrictions on the resin used to dilute the resin composite, but the resins exemplified as components of the resin composite can be used. Furthermore, one preferred embodiment is that the resins constituting the resin composite and the diluting resin are of the same type.

[0067] There are no particular restrictions on the solvent used to dilute the resin composite, but any solvent capable of dissolving the resins constituting the resin composite can be used.

[0068] There are no particular restrictions on the amount of resin composite and resin used, but it is preferable to adjust the amount of resin composite and resin used so that, for example, the amount of CNTs in 100% by mass of the resulting resin composition is, for example, 0.05% by mass or more and less than 3% by mass, preferably 0.07 to 1% by mass, and more preferably 0.09 to 0.5% by mass.

[0069] There are no particular restrictions on the amount of resin composite and solvent used, but it is preferable to adjust the amount of resin composite and solvent used so that, for example, the amount of CNTs in 100% by mass of the resulting resin composition is, for example, 0.005 to 0.5% by mass, preferably 0.007 to 0.1% by mass, and more preferably 0.009 to 0.05% by mass.

[0070] When mixing, one method is to mix the resin composite and the resin in a kneader. As the kneader, an extruder such as a single-screw extruder or a twin-screw extruder can be used. There are no particular restrictions on the mixing conditions, but it is preferable to set the conditions considering the melting point of the resin.

[0071] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0072] [Manufacturing Example 1] (Manufacturing of a Carbon Nanotube Forest) A wafer (substrate) coated with a catalyst for carbon nanotube growth was prepared, and vertically oriented carbon nanotubes were grown from the catalyst by chemical vapor deposition to produce a vertically oriented carbon nanotube forest oriented perpendicular to the wafer. The carbon nanotubes constituting the carbon nanotube forest were multi-walled carbon nanotubes, with an average length of 250 μm per nanotube, an average diameter of 6 to 10 nm, a carbon purity of 99.8% or higher, and a crystallinity (D / G ratio) of 0.6 to 0.8.

[0073] [Production Example 2] (Preparation of Polyamide 6 Solution) 4.5 g of polyamide 6 (PA6) (LIBOLON N150-300) was added to 25.5 g of 2,2,2-trifluoroethanol, and the PA6 was dissolved by stirring to prepare a PA6 solution.

[0074] [Example 1] (Manufacturing of PA6-impregnated CNTs) 0.6 g of carbon nanotube forest formed on the wafer obtained in Manufacturing Example 1 was immersed in a 0.7 g PA6 solution, with the substrate facing upwards and the carbon nanotube forest facing downwards, starting from the carbon nanotube forest side. The forest was thoroughly immersed (for about 1 minute) until all air bubbles were released from between the carbon nanotube forests, and the entire PA6 solution was impregnated into the carbon nanotube forest. The solvent was removed by air drying the impregnated carbon nanotube forest, and then it was scraped off the wafer using a scraper to obtain PA6-impregnated carbon nanotubes. The above operation was repeated to obtain 500 g of PA6-impregnated carbon nanotubes. The PA6-impregnated carbon nanotubes were pulverized using a force mill to obtain powdered PA6-impregnated carbon nanotubes.

[0075] (Manufacturing of Resin Composite 1) Powdered PA6-impregnated carbon nanotubes and PA6 were mixed in a twin-screw extruder at a temperature of 260-280°C, with PA6 introduced from the main feeder and powdered PA6-impregnated CNTs from the sub-feeder, so that the CNTs constituted 5% by mass and PA6 from 95% by mass, thereby obtaining strands of Resin Composite 1 (CNTs: 5% by mass, PA6: 95% by mass) and pellets obtained by cutting the strands.

[0076] (Manufacturing of Resin Composite 2) Powdered PA6-impregnated carbon nanotubes and PA6 were kneaded under the same conditions as for Resin Composite 1, except that the amount of CNTs was 10% by mass and PA6 was 90% by mass, thereby obtaining strands of Resin Composite 1 (CNTs: 10% by mass, PA6: 90% by mass) and pellets obtained by cutting the strands.

[0077] [Comparative Example 1] A 0.6 g carbon nanotube forest formed on the wafer obtained in Manufacturing Example 1 was scraped off the wafer using a scraper to obtain carbon nanotubes. The above operation was repeated to obtain 500 g of carbon nanotubes. The carbon nanotubes and PA6 were kneaded under the same conditions as for resin composite 1, except that the composition was 5% by mass of CNTs and 95% by mass of PA6, or 10% by mass of CNTs and 90% by mass of PA6. However, uniform kneading was not possible, and a resin composite could not be obtained.

[0078] [Evaluation] [Surface Resistance] The surface resistance (Ω / sq) of the strands of resin composite 1 and resin composite 2 obtained in Example 1 was measured using a contact-type sheet resistance / resistivity measurement system (four-probe method).

[0079] The surface resistance of resin composite 1 is 1.969 Ω / sq, and the surface resistance of resin composite 2 is 2.513 × 10⁻⁶. -2 It was Ω / sq.

[0080] [Manufacturing of Molded Articles] The following molded articles were manufactured using pellets of resin composite 1 and resin composite 2 from Example 1, and pellets of PA6 (LIBOLON N150-300).

[0081] Dumbbell-shaped test specimens (JIS K7139 (2009), Type A1) were manufactured by injection molding of resin composite or PA6 pellets using an injection molding machine (PLASTARSi-100V (injection device: F200HC), manufactured by Toyo Machinery & Metal Co., Ltd.) (injection temperature 260°C to 280°C).

[0082] [Tensile Modulus and Yield Strength] The obtained dumbbell-shaped test specimens were measured using a Shimadzu Corporation tensile testing machine in accordance with JIS K7161 (2014) under the following conditions: measurement temperature 23±2℃, 50±5%RH, tensile speed 50 mm / min, and chuck distance 100 mm. The tensile modulus (MPa) and yield strength (MPa) of the test specimens in the MD direction were measured.

[0083] The evaluation results of the molded articles for each example and comparative example are shown in Table 1 below.

[0084]

[0085] The above experiments confirmed that the resin composite of this disclosure exhibits excellent conductivity and mechanical strength.

Claims

1. Surface resistance is 1 × 10⁻⁶ -5 A resin composite having a resistance of ~1 × 10 Ω / sq and a tensile strength of 50 to 500 MPa according to JIS K7161, measured on a Type A1 dumbbell-shaped tensile test specimen conforming to JIS K7139.

2. The resin composite according to claim 1, wherein the resin content is 80 to 97% by mass in 100% by mass of the resin composite.

3. The resin composite according to claim 1, wherein the resin composite contains 3 to 20% by mass of carbon nanotubes in 100% by mass of the resin composite.

4. A method for producing a resin composite containing a resin and carbon nanotubes, comprising the steps of: preparing a resin solution and a carbon nanotube forest formed on a substrate; immersing the carbon nanotube forest in the resin solution; peeling the resin-impregnated carbon nanotubes from the substrate after immersion; and kneading the resin-impregnated carbon nanotubes with the resin.

5. Use of the resin composite according to claim 1 as a masterbatch.

6. A method for producing a resin composition, comprising the step of diluting the resin composite described in claim 1 with at least one of a resin and a solvent.

7. The method for producing a resin composition according to claim 6, wherein the dilution step is a step of kneading the resin composite with the resin.

8. A resin composition obtained by diluting the resin composite described in claim 1 with at least one of a resin and a solvent.

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