Composite, resin composition, and method for producing composite

Abstract

One embodiment of the composite of the present disclosure is a composite containing carbon nanotubes and a dispersant, where X represents the content of the carbon nanotubes with respect to 100 mass% of the composite and Y represents the ratio calculated from an image of a broken sample of the composite, in 80% or more of a plurality of images, X and Y satisfy 0.5 X < = Y < = 0.8 X, where X represents the content of the carbon nanotubes with respect to 100 mass% of the composite, and Y represents the ratio calculated from the image of the broken sample of the composite.

Description

Technical Field

[0001] This invention relates to composites, resin compositions, and methods for manufacturing composites. Background Technology

[0002] Carbon nanotubes are known to be commonly used in resin blends, but they are difficult to disperse in resins. When carbon nanotubes aggregate or become dispersible in resins, the physical properties of the resin cannot be fully improved. For example, Patent Document 1 discloses a carbon nanotube composition in which carbon nanotubes can be added to a resin at a high concentration. The composition is a solid carbon nanotube composition made by mixing 30 to 70% by weight of carbon nanotubes and 30 to 70% by weight of silicone oil with a repeat number of 3 to 100,000 silicon-oxygen bonds. Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2007-231219 Summary of the Invention The technical problem that the invention aims to solve

[0004] However, even when the carbon nanotube composition described in Patent Document 1 is mixed with resin, there are still cases where the carbon nanotubes agglomerate or become misaligned, and the physical properties of the resin cannot be sufficiently improved. Therefore, the object of this disclosure is to provide a composite that exhibits good dispersion of carbon nanotubes when mixed with resin and has excellent mechanical properties of the resin composition, a method for manufacturing the same, and a resin composition comprising the composite.

[0005] means of solving technical problems

[0006] One form of the composite disclosed herein comprises carbon nanotubes and a dispersant, wherein, Let X (mass%) be the content of the carbon nanotubes relative to 100% of the composite, and Y (%) be the following proportion. In more than 80% of the images taken under the condition that the total length of the boundary lines is more than 7.0 μm and less than 9.0 μm, X and Y satisfy the following formula (1): 0.5X≤Y≤0.8X (1) Ratio: For the fractured sample obtained by breaking the composite sample, an image is obtained using a scanning electron microscope (SEM). The image contains the boundary between the fractured portion of the fractured sample and the space outside the composite, with the length of the continuous boundary line being greater than 0.6 μm and less than 2.1 μm in each image. In this case, the ratio of the length of the portion from carbon nanotubes with a thickness of less than 0.1 μm at a height of 0.2 μm from the boundary to the length of the boundary line is obtained. Invention Effects

[0007] According to the present invention, a composite having good dispersibility of carbon nanotubes when compounded with a resin and excellent mechanical properties of the resin composition, a method for manufacturing the same, and a resin composition comprising the composite are available. Attached Figure Description

[0008] Figure 1 These are SEM images 1-7 of the fractured portion of the composite membrane in Example 1. Figure 2 The images shown are SEM images c1 to c7 of the fractured portion of the composite in Comparative Example 1. Detailed Implementation

[0009] In this specification, the numerical range A to B refers to values ​​above A and below B. In this specification, when the units of the values ​​before and after the "~" indicating a numerical range are the same, the unit of the value before the "~" may sometimes be omitted.

[0010] In this specification, carbon nanotubes are also referred to as "CNTs", and carbon nanotube forests are also referred to as "CNT forests".

[0011] [Complex] <Carbon nanotubes> The composite disclosed herein comprises carbon nanotubes (CNTs).

[0012] CNTs can be manufactured using methods known in the art. For example, CNTs can be manufactured using methods such as thermochemical vapor deposition (thermal CVD), plasma CVD, laser ablation, arc discharge, or combustion.

[0013] The average length of CNTs is preferably 10–1000 μm, more preferably 30–800 μm, and even more preferably 50–500 μm. The average length of CNTs can be adjusted, for example, by adjusting the CVD process time, i.e., the CNT growth time. The average diameter of CNTs is preferably 1–50 nm, more preferably 3–30 nm, and even more preferably 5–15 nm. The average diameter of CNTs can be adjusted, for example, by adjusting the thickness of the catalyst layer and the type of catalyst.

[0014] The average length and average diameter of CNTs were determined using scanning electron microscopy (SEM) or transmission electron microscopy (TEM). Specifically, 10 CNT images were captured using SEM or TEM. For each of the 10 images, 10 length measurement points were randomly selected and measured, resulting in a total of 100 length measurements. The arithmetic mean of these 100 length measurements was then calculated to determine the average length of the CNT. Similarly, for each of the 10 images, 10 diameter measurement points were randomly selected and measured, resulting in a total of 100 diameter measurements. The arithmetic mean of these 100 diameter measurements was then calculated to determine the average diameter of the CNT.

[0015] The carbon purity of CNTs is preferably 95.0% to 99.999%. The lower limit of the carbon purity of CNTs is preferably 96.0%, more preferably 97.0%, even more preferably 98.0%, even more preferably 99.0%, and particularly preferably 99.8%. The upper limit of the carbon purity of CNTs can be, for example, 99.99% or 99.9%. The carbon purity of CNTs can be determined, for example, by elemental analysis using fluorescent X-rays.

[0016] The crystallinity of CNTs can be evaluated, for example, using Raman spectroscopy. In Raman-based crystallinity evaluation, the D / G ratio is used as an indicator. The D / G ratio is the ratio that appears at 1360 cm⁻¹ in the Raman spectrum. -1 The D / G ratio is the ratio of the peak intensity of the D band near 1580 cm⁻¹ to the peak intensity of the G band near 1580 cm⁻¹. A smaller D / G ratio indicates a higher degree of crystallinity of the carbon nanotubes. The preferred D / G ratio is 0.5 to 1.0, more preferably 0.6 to 0.8.

[0017] The carbon purity and crystallinity of CNTs can be adjusted, for example, by adjusting the thickness of the buffer layer of 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 feed gas in the CVD process, and the temperature and pressure in the reaction chamber.

[0018] CNTs can be single-walled carbon nanotubes or multi-walled carbon nanotubes with two or more layers. Multi-walled carbon nanotubes are preferred. The number of layers in multi-walled carbon nanotubes is not particularly limited, but is preferably 2 to 20.

[0019] The composite disclosed herein can be manufactured, for example, using CNT powder and a dispersant. CNT powder refers to powder containing multiple CNTs. CNT powder is obtained by scraping CNTs from a CNT forest off a substrate using a scraper or the like.

[0020] A CNT forest refers to an aggregate of multiple CNTs arranged on a substrate and oriented in a direction perpendicular to the substrate surface. In a CNT forest, multiple CNTs stand side by side on the substrate.

[0021] CNT forests can be obtained, for example, by chemical vapor deposition (CVD) using a catalyst substrate having a substrate and a catalyst layer disposed on the substrate. CVD is a method in which the catalyst substrate is placed in a reaction chamber, a feed gas is supplied to the reaction chamber, and CNTs are grown on the surface of the catalyst layer. Thermal CVD is preferred as the CVD method.

[0022] Examples of substrates include silicon substrates, alumina substrates, magnesium oxide substrates, glass substrates, sapphire substrates, and stainless steel substrates.

[0023] The catalyst layer can be formed, for example, by sputtering catalyst particles onto a substrate. Catalysts can be metals, specifically alloys containing at least one metal selected from iron (Fe), nickel (Ni), cobalt (Co), molybdenum (Mo), and gold (Au). Examples of alloys include ferroalloys, nickel alloys, and cobalt alloys. Catalysts can be metal precursors such as metal oxides and metal compounds. Examples of metal oxides include iron oxides, nickel oxides, and cobalt oxides. Examples of metal compounds include ferric chloride. When using precursors, they need to be converted into metals before CVD by heating or the like.

[0024] The catalyst substrate described above may have a buffer layer between the substrate and the catalyst layer. Examples of materials used for the buffer layer include silicon dioxide (SiO2), aluminum oxide (Al2O3), silicon nitride (SiN), zinc oxide (ZnO), copper oxide (Cu2O), and nickel oxide (NiO). The buffer layer can be formed, for example, by sputtering.

[0025] Sputtering for forming a catalyst layer and sputtering for forming a buffer layer can be carried out according to the sputtering target using known apparatus and conditions. The sputtering pressure is preferably 0.01 to 10 Pa, more preferably about 0.1 to 1 Pa.

[0026] Carbon-containing gases can be used as feedstock gases, such as hydrocarbons, sulfur-containing organic gases, phosphorus-containing organic gases, carbon monoxide, and alcohols. Examples of hydrocarbons include: alkanes such as methane and ethane; olefins such as ethylene and butadiene; alkynes such as acetylene; aromatics such as benzene, toluene, and styrene; aromatics with fused rings such as indene, naphthalene, and phenanthrene; cycloalkanes such as cyclopropane and cyclohexane; cycloolefins such as cyclopentene; and alicyclic hydrocarbons with fused rings such as steroids. Examples of alcohols include methanol and ethanol. From the viewpoint of the carbon purity of the resulting CNTs, hydrocarbons are preferred as feedstock gases.

[0027] A carrier gas, which is supplied to the reaction chamber along with the raw material gas, can be used to transport the raw material gas. Examples of carrier gases include helium, neon, argon, nitrogen, and hydrogen.

[0028] From the perspective of CNT growth rate and carbon purity of the obtained CNTs, the temperature in the reaction chamber of the CVD method is preferably 600-850℃, more preferably 650-800℃. From the perspective of CNT growth rate and purity, the pressure inside the reaction chamber in the CVD process is preferably atmospheric pressure. However, depending on other conditions during the CVD process, the pressure inside the reaction chamber can also be atmospheric pressure with reduced pressure or pressurized pressure.

[0029] The average length and average diameter of CNTs in a CNT forest are, for example, the same as the average length and average diameter of CNTs mentioned above.

[0030] <Dispersant> The composite disclosed herein contains a dispersant. Examples of dispersants include liquid polymers, uncured rubber, thermoplastic elastomers, surfactants, and resin-based dispersants. Examples of liquid polymers include silicone oils, polyalkylene glycols, polyethylene glycols, polycarbonate polyols, polyester polyols, and polyether polyols. Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. They can be used individually or in combination.

[0031] Examples of anionic surfactants include fatty acid salts, polysulfonates, polycarboxylates, alkyl sulfates, alkylaryl sulfonates, alkylnaphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl phosphates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylaryl ether sulfates, naphthalene sulfonic acid formaldehyde condensates, polyoxyethylene alkyl phosphate sulfonates, glyceryl borate fatty acid esters, and polyoxyethylene glyceryl fatty acid esters. Specific examples include sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene nonylphenyl ether sulfate, and sodium salts of β-naphthalene sulfonic acid formaldehyde condensates.

[0032] Examples of cationic surfactants include alkylamine salts and quaternary ammonium salts. Specific examples include stearamine acetate, behenyltrimethylammonium chloride, tallow trimethylammonium chloride, dioleyldimethylammonium chloride, oleylmethyldiethanolammonium chloride, tetramethylammonium chloride, laurylpyridine chloride, laurylpyridine bromide, laurylpyridine disulfide, hexadecylpyridine bromide, 4-alkylmercaptopyridine, polybrominated dodecyl (vinylpyridine), and dodecylbenzyltriethylammonium chloride. Examples of amphoteric surfactants include aminocarboxylate salts.

[0033] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene derivatives, polyoxyethylene phenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and alkyl allyl ethers. Specific examples include polyoxyethylene lauryl ether, sorbitan fatty acid esters, and polyoxyethylene octylphenyl ether.

[0034] Examples of resin-type dispersants include fluorinated resins, cellulose derivatives, polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, hydrogenated nitrile rubber, and polyacrylonitrile polymers. Examples of cellulose derivatives include cellulose acetate, cellulose acetate butyrate, cellulose butyrate, cyanoethyl cellulose, ethyl hydroxyethyl cellulose, nitrocellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, and carboxymethyl cellulose.

[0035] From the viewpoint of the dispersibility of CNTs in the resulting resin composition, a silicone-based dispersant is preferred. Examples of silicone-based dispersants include, for example, silicone oil. Examples of silicone oils include, for example, dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, methanol-modified silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, and fluorine-modified silicone oil. Dimethyl silicone oil is preferred as the silicone-based dispersant. From the viewpoint of the dispersibility of CNTs in the obtained resin composition, the mass ratio of carbon nanotubes to dispersant in the above composite (carbon nanotubes: dispersant) is preferably 1:0.5 to 1:10, more preferably 1:0.7 to 1:7, and even more preferably 1:1 to 1:5.

[0036] <Other Ingredients> The composites disclosed herein may further comprise components other than CNTs and dispersants (hereinafter also referred to as "other components"). Examples of other components include, for example, fibrous fillers, powdered fillers, and resin additives. Examples of fibrous fillers include, for example, carbon fibers, organic fibers, metal fibers, and glass fibers. Examples of resin additives include, for example, antioxidants, heat stabilizers, light stabilizers, weather stabilizers, hydrolysis inhibitors, plasticizers, colorants, flame retardants, foaming agents, nucleating agents, pigments, lubricants, and stretching agents. Other ingredients may be one or more.

[0037] The composite is preferably formed substantially of carbon nanotubes and a dispersant. In fact, the content of carbon nanotubes and the dispersant is 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more, relative to 100% by mass of the composite.

[0038] <Morphology of the complex> The aforementioned composite is, for example, a continuous membrane. Membrane-like composites are also called "composite membranes." Examples of shapes for composite membranes include rectangles, squares, trapezoids, parallelograms, rhombuses, kites, ellipses, circles, and irregular shapes. When the composite is obtained using three rollers as described later, the shape of the composite can be, for example, an unshaped strip. Strip-shaped composites can, for example, be folded. From the viewpoint that the composite film can be easily torn by hand for image analysis as described later, the thickness of the composite film is preferably 10 nm to 2.0 mm, more preferably 100 nm to 100 μm, and even more preferably 1 μm to 30 μm.

[0039] <Image Analysis of Complexes> When the content of carbon nanotubes relative to 100% mass of the composite is denoted as X (mass%), and the proportion calculated from the images of the fractured sample of the composite is denoted as Y (%), in more than 80% of the images, X and Y satisfy the following equation (1): 0.5X≤Y≤0.8X (1) For the fractured sample obtained by fracturing the composite sample, images were obtained using scanning electron microscopy (SEM). These images contained the boundary between the fractured portion of the fractured sample and the space outside the composite, with the length of the continuous boundary line being greater than 0.6 μm and less than 2.1 μm in each image. In this case, the length of the portion from the carbon nanotubes with a thickness of less than 0.1 μm at a height of 0.2 μm from the boundary was obtained relative to the length of the boundary line.

[0040] X can be calculated by the amount of carbon nanotubes mixed in when manufacturing the composite.

[0041] When acquiring images using SEM, a fractured sample is prepared by breaking a sample of the aforementioned composite. The composite sample is, for example, a composite that can be torn by hand. A composite membrane can be cited as an example of a composite sample. A fractured sample refers to a sample having a fractured portion created by breaking the composite sample. A method for breaking the composite sample can be, for example, tearing the sample by hand.

[0042] Obtaining an image of a fractured sample using SEM refers to observing the fractured portion and acquiring an SEM image in a manner that includes the fractured portion and the space outside the composite body at least 0.2 μm above the fractured portion, and where the length of the continuous boundary line between the fractured portion and the space outside the composite body is between 0.6 μm and 2.1 μm. The method for calculating the length of the aforementioned boundary line will be described later. When the composite sample is a composite membrane, SEM observation is performed along the direction of the top view of the composite membrane, such that the fractured portion and the space outside the composite membrane at least 0.2 μm above the fractured portion are reflected. The term "top view of the composite membrane" refers to a planar composite membrane viewed from its normal direction.

[0043] Based on the magnification of the SEM observation, the correspondence between one pixel in the SEM image and the length of the actual space is determined. From the viewpoint of resolution, the SEM observation magnification is preferably set such that one pixel in the obtained image corresponds to 1 to 20 nm of the actual space, and more preferably set such that one pixel corresponds to 1 to 10 nm of the actual space. Multiple images were obtained using SEM to ensure that the total length of the aforementioned boundary lines was greater than 7.0 μm and less than 9.0 μm.

[0044] The boundary between the fractured portion and the space outside the composite body is determined, for example, as follows. More specifically, it is done by the method described in the embodiments. First, the SEM images of the fractured sample are converted to grayscale images with 256 levels (0-255). Grayscale conversion is performed, for example, by applying a suitable filter to the SEM image. Next, the maximum and minimum pixel values ​​in each SEM image are determined. The SEM image is normalized by subtracting the minimum pixel value in the SEM image from the pixel value of each pixel, dividing by the difference between the maximum and minimum values ​​(the range of pixel values), and then multiplying by 255.

[0045] Then, the normalized SEM image is configured such that the composite is located below the image and the space outside the composite is located above the image. The pixel values ​​of each pixel are observed along the vertical direction. The pixel (point) at the bottom of the group of pixels whose pixel values ​​(pixel values ​​in the normalized image) differ from adjacent pixels in the vertical direction by more than 30 is recorded. This operation is performed across the entire range of the SEM image in the horizontal direction (vertical direction of the vertical direction) to generate a set A consisting of these points. These points are then connected to form a temporary boundary line.

[0046] For each point belonging to set A, calculate the moving average of five points, including the given point, its two nearest neighbors to the left, and its two nearest neighbors to the right, to generate set A'. If adjacent points in set A are significantly separated in the vertical direction from each other in the horizontal direction, remove points far from the moving average from set A, generating set B. Connect the points belonging to set B to form the boundary between the fractured portion and the space outside the complex.

[0047] The calculation of Y is performed, for example, in the following manner. More specifically, it is performed using the method described in the embodiments. First, the length of the boundary line between the determined fracture and the space outside the composite is measured by converting the number of pixels. Then, considering the correspondence between one pixel and the length of the actual space, the length of the boundary line of the actual space is calculated. Next, identify the pixels corresponding to the space outside the composite body 0.2 μm above the aforementioned boundary. Observe the pixel values ​​of these pixels in the left-right direction, and check and record the region D from points where the pixel value increases by 7 levels or more (points brighter than 7 levels) to points where the pixel value decreases by 7 levels or more (points darker than 7 levels). At this time, the aforementioned region can be detected either to the right or to the left. Perform the above operation across the entire left-right range within the SEM image to determine all of the aforementioned regions.

[0048] After determining the length of each region by converting it to pixel count, the length of the actual space is calculated. Regions D' with a length of less than 0.1 μm in actual space are extracted from all the regions D. Y is calculated by adding the lengths of all extracted regions D' and dividing by the length of the boundary line.

[0049] Y can be adjusted by changing the type of mixer and mixing conditions when mixing carbon nanotubes with dispersants. Examples of mixing conditions include, for instance, the mixing time, and, when using a three-roll mixer, the speed of the rolls and the distance between them.

[0050] In more than 80% of the multiple images taken with a total boundary length of more than 7.0 μm and less than 9.0 μm, X and Y satisfy the following equation (1). 0.5X≤Y≤0.8X (1)

[0051] Y within the range of Equation (1) above means that CNTs are well dispersed in the complex and are less likely to aggregate or become biased. By satisfying Equation (1) in more than 80% of the images mentioned above, it can be confirmed that the CNTs are uniformly dispersed in the composite. When the CNTs are uniformly dispersed in the composite, the CNTs in the resin composition prepared by mixing the composite with the resin have good dispersibility.

[0052] Equation (1) is preferably Equation (1'), and more preferably Equation (1”). 0.505X≤Y≤0.75X(1') 0.51X≤Y≤0.72X(1”)

[0053] In the above-mentioned multiple images, preferably more than 85%, more preferably more than 90%, further preferably more than 95%, and especially preferably in all images, X and Y satisfy the above formula (1).

[0054] By taking multiple images in which the length of continuous boundary lines contained in each image is greater than 0.6 μm and less than 2.1 μm, so that the total length of the boundary lines is greater than 7.0 μm and less than 9.0 μm, the measurement error caused by the bias of CNTs in the sample of the complex can be reduced.

[0055] <Manufacturing Method of Composite> As a method for manufacturing the above-mentioned composite, for example, a method is provided that involves using three rollers to mix CNT and a dispersant until X and Y satisfy the above formula (1). In the process of mixing CNTs and dispersants using three rollers, CNTs and dispersants can be added to the three rollers simultaneously or alternately. Alternatively, a pre-mixed mixture of CNTs and dispersants can be added to the three rollers.

[0056] In the process of mixing CNTs and dispersants using three rollers, it is preferable to perform overmixing for 10 minutes after adding CNTs and dispersants to the three rollers, more preferably for 20 minutes or more, even more preferably for 30 minutes or more, and particularly preferably for 45 minutes or more. The mixing time after adding CNTs and dispersants to the three rollers is, for example, less than 3 hours.

[0057] The rotational speed of the three rollers is preferably 50 to 1000 rpm, more preferably 100 to 900 rpm, and even more preferably 150 to 800 rpm. The spacing between the feed roller and the intermediate roller of the three rollers is preferably 5–200 μm, more preferably 7–150 μm, and even more preferably 10–100 μm. The spacing between the intermediate roller and the finishing roller of the three rollers is preferably 5–200 μm, more preferably 7–150 μm, and even more preferably 10–100 μm.

[0058] In the process of mixing CNT and dispersant using three rollers, it is preferable to narrow the gap between the feed roller and the intermediate roller at regular intervals. This narrowing of the gap at regular intervals can also be performed multiple times. When this narrowing operation is performed multiple times, the initial and final intervals can differ in each iteration. Alternatively, the gap between the feed roller and the intermediate roller can be widened after each narrowing.

[0059] [Resin Composition] The resin composition disclosed herein comprises the above-described composite and a resin. Examples of resins include thermoplastic resins and thermosetting resins. One type of resin may be used, or two or more types may be used.

[0060] Examples of thermosetting resins include epoxy resins, unsaturated polyester resins, (meth)acrylic resins containing unsaturated groups, vinyl ester resins, urethane resins, (meth)acrylic urethane resins, phenolic resins, melamine resins, urea resins, diallyl phthalate resins, cyanate ester resins, alkyd resins, and thermosetting polyimide resins.

[0061] 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.

[0062] Examples of polyolefins include high-density polyethylene, medium-density polyethylene, low-density polyethylene produced by high-pressure process, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, polypropylene, and ethylene-propylene copolymer. Examples of styrene resins include polystyrene, styrene-maleic anhydride copolymer, AS resin, and ABS resin.

[0063] Examples of polyesters include polyethylene terephthalate and polybutylene terephthalate. 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.

[0064] The resin is preferably selected from at least one resin selected from thermoplastic resins and thermosetting resins, more preferably thermoplastic resins, and even more preferably polyolefins or polyamides.

[0065] The resin composition described above may also contain other components that may be included in the composite described above. Additionally, the resin composition may also contain inorganic fillers. The inclusion of inorganic fillers in the resin composition improves its mechanical properties. Examples of inorganic fillers include: alumina, aluminum hydroxide, zirconium hydroxide, barium hydroxide, calcium hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, magnesium sulfate, titanium dioxide, tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, calcium oxide, magnesium oxide, zinc oxide, molybdenum oxide, antimony oxide, nickel oxide, calcium silicate, beryllium, calcium titanate, silicon carbide, silicon nitride, aluminum nitride, boron nitride, titanium dioxide, zinc borate, and aluminum borate; talc; clay; mica; and glass. Metal oxides and metal nitrides such as fibers, kaolin, hydrotalcite, wollastonite, calcium silicate, dicalcium phosphate, calcium phosphate, glass flakes, hydrated glass, and sepiolite; hydrated metal compounds; silica-based fillers such as molten pulverized silica, molten spherical silica, crystalline silica, amorphous silica, secondary condensed silica, micronized silica, hollow silica, and porous silica; nitride-based fillers and carbon-based fillers such as silicon carbide, silicon nitride, titanium carbide, and diamond.

[0066] The above-mentioned resin composition can be manufactured, for example, by melt-blending the above-mentioned composite, resin, and, if necessary, inorganic fillers and other components. Melt-blending can be carried out, for example, using a single-spindle extruder, a twin-spindle extruder, a Banbury mixer, a kneader, or a roller mill. When the above-mentioned resin composition further contains inorganic fillers or other components, the composite, resin, inorganic fillers or other components can be fed into a twin-screw extruder or the like for melt mixing. Alternatively, the resin can be pre-mixed with the inorganic fillers or other components to form a mixture, and then the composite and mixture can be fed into a twin-screw extruder or the like for melt mixing. After melt mixing, the above-mentioned resin composition can be formed into granules.

[0067] The CNT content in the above resin composition is preferably 0.01 to 10% by mass relative to 100% by mass of the resin composition, more preferably 0.01 to 5% by mass, even more preferably 0.05 to 1% by mass, and particularly preferably 0.05 to 0.5% by mass. When the above resin composition contains inorganic fillers, the content of inorganic fillers relative to 100% by mass of the resin composition is preferably 1 to 30% by mass, more preferably 5 to 25% by mass, and even more preferably 10 to 20% by mass.

[0068] [molded body] The above-mentioned resin composition can be shaped using various known methods. These shaping methods include, for example, extrusion molding, compression molding, injection molding, calendering, and blow molding. The aforementioned molded parts can be used, for example, as automotive parts, parts for vehicles other than automobiles, marine parts, aerospace parts, sporting goods, home appliance material parts, communication equipment parts, electrical parts, electronic parts, medical equipment parts, mechanical parts, power tool parts, building material-related parts, civil engineering parts, agricultural materials, food containers or films.

[0069] By using the above-described composite, a resin composition with good dispersibility of CNTs can be manufactured. Using such a resin composition, molded articles with excellent mechanical properties can be manufactured.

[0070] This invention relates, for example, to the following [1] to [8]. [1] A composite comprising carbon nanotubes and a dispersant, wherein, When the content of the carbon nanotubes relative to 100% by mass of the composite is denoted as X (mass%), and the proportion calculated from the images of the fractured sample of the composite is denoted as Y (%), in more than 80% of the images in multiple images, X and Y satisfy the following equation (1): 0.5X≤Y≤0.8X (1) For the fractured sample obtained by fracturing the composite, images were obtained using scanning electron microscopy (SEM). The images included the boundary between the fractured portion of the fractured sample and the space outside the composite, with the length of the continuous boundary line being greater than 0.6 μm and less than 2.1 μm in each image. In this case, the length of the portion from carbon nanotubes with a thickness of less than 0.1 μm at a height of 0.2 μm from the boundary was obtained relative to the length of the boundary line. [2] The composite as described in [1] has a mass ratio of carbon nanotube content to dispersant content (carbon nanotube: dispersant) of 1:0.5 to 1:10. [3] The composite as described in [1] or [2], wherein the dispersant is an organosilicon dispersant. [4] The composite as described in any one of [1] to [3], wherein it is a membrane. [5] A resin composition comprising any one of [1] to [4] a composite and a resin. [6] The resin composition as described in [5], wherein the resin is at least one selected from thermoplastic resins and thermosetting resins. [7] The resin composition as described in [5] or [6] further comprises inorganic filler. [8] A method for manufacturing a composite comprising carbon nanotubes and a dispersant, comprising a step of mixing the carbon nanotubes and the dispersant using three rollers. When the content of the carbon nanotubes relative to 100% by mass of the composite is denoted as X (mass%), and the proportion calculated from the images of the fractured sample of the composite is denoted as Y (%), in more than 80% of the images in multiple images, X and Y satisfy the following equation (1): 0.5X≤Y≤0.8X (1) For the fractured sample obtained by fracturing the composite, images were obtained using scanning electron microscopy (SEM). The images included the boundary between the fractured portion of the fractured sample and the space outside the composite, with the length of the continuous boundary line being greater than 0.6 μm and less than 2.1 μm in each image. In this case, the length of the portion from carbon nanotubes with a thickness of less than 0.1 μm at a height of 0.2 μm from the boundary was obtained relative to the length of the boundary line. Example

[0078] The present invention will be further described in detail below based on the embodiments, but the present invention is not limited to these embodiments.

[0079] [Manufacturing Example 1] (The creation of carbon nanotube forests) A wafer is prepared with a catalyst for carbon nanotube growth, and vertically oriented carbon nanotubes are grown from the catalyst using a chemical vapor deposition method to create a forest of vertically oriented carbon nanotubes that are vertically oriented relative to the wafer. The carbon nanotubes that make up the carbon nanotube forest are multi-walled carbon nanotubes, each with an average length of 250 μm, an average diameter of 6–10 nm, a carbon purity of over 99.8%, and a crystallinity (D / G ratio) of 0.6–0.8.

[0080] (Manufacturing of carbon nanotubes) Approximately 0.6 g of the carbon nanotube forest formed on the wafer was scraped off the wafer using a scraper to obtain carbon nanotube powder. The same operation was repeated to prepare 10 g of carbon nanotube powder for each example and comparative example.

[0081] [Example 1] (Preparation of the composite) 10g of the above-mentioned carbon nanotube powder and 20g of silicone oil (Shin-Etsu silicone, KF-96-1000CS, dimethyl silicone oil) were added alternately in small amounts to the feed roller and intermediate roller of a three-roller system (manufactured by Shenzhen Zhongyi Technology Co., Ltd., ZYTR-80E) while mixing. The total amount was added over 20 minutes. The three rollers were set with the interval between the feed roller and the intermediate roller being 50μm, the interval between the intermediate roller and the finishing roller being 74μm, and the rotation speed being 300rpm.

[0082] During the mixing process, as the mixture appears on the scraper, it is repeatedly fed back between the feed roller and the intermediate roller while being concentrated into powdered carbon nanotubes by silicone oil. After approximately 20 minutes of mixing, to further improve cohesion, the gap between the feed roller and the intermediate roller was set to 40 μm, and then the mixing was carried out for another 20 minutes.

[0083] To eliminate uneven mixing and to ensure that all the mixture is removed from the rollers at once, the gap between the feed roller and the intermediate roller is 15 μm, and the gap between the intermediate roller and the finishing roller is also 15 μm. As a result, almost all the mixture inside the rollers appears on the scraper.

[0084] After all the mixture is removed at once, it is fed back between the feed roll and the intermediate roll for further mixing. During mixing, the gap between the feed roll and the intermediate roll narrows by 10 μm every 5 minutes, from 70 μm to 30 μm. The gap between the intermediate roll and the finishing roll is 15 μm. Then, the gap between the feed roller and the intermediate roller was increased from 30 μm to 50 μm, and the mixing state was confirmed by visually checking for uneven blackness in the mixture. Then, the mixing process was repeated. During mixing, the gap between the feed roller and the intermediate roller was narrowed by 10 μm every 5 minutes, from 50 μm to 30 μm.

[0085] A concentrated, uniform, black, continuous composite film is finally obtained. The time required from adding carbon nanotube powder and silicone oil to the three rollers until the above-mentioned composite film is obtained is approximately 80 minutes. The resulting composite film can be easily torn by external force.

[0086] (Acquisition of SEM images) The composite membrane obtained in Example 1 was manually torn to expose the fracture. The exposed fracture was then observed using SEM at an accelerating voltage of 20 kV and a magnification of 5000x. The SEM observation was performed along the top-view direction of the composite membrane. Seven SEM images were obtained in a manner that ensured that the fracture surface region included in each image was not repeated.

[0087] The obtained SEM images were filtered (0.2126*red+0.7152*green+0.0722*blue) to obtain SEM images 1-7 with 256 gray levels (0-255). One pixel in the obtained SEM image corresponds to a 4nm square region in the space outside the complex and the complex.

[0088] (Determine the boundary between the fractured portion and the space outside the composite body) In the obtained SEM images 1 to 7, the boundary between the fractured part of the composite and the space outside the composite is determined in the following order (1) to (9).

[0089] (1) The maximum and minimum pixel values ​​in the SEM image are determined. The SEM image is normalized by subtracting the minimum pixel value in the SEM image from the pixel value of each pixel, dividing by the difference between the maximum and minimum values ​​(the range of pixel values), and then multiplying by 255. If the pixel value of the pixel corresponding to the text portion such as the scale bar in the SEM image is the maximum value, the above normalization is performed only using the pixels other than the text portion.

[0090] (2) In order to visually distinguish the space outside the complex from the complex, the normalized SEM image in (1) above is configured such that the complex is located below the image and the space outside the complex is located above the image. In this configured image, the up and down direction is set as the y-axis direction, the left and right direction is set as the x-axis direction, the right direction is set as the positive x-axis direction, the up direction is set as the positive y-axis direction, and the lower left vertex of the image is set as the origin.

[0091] (3) Let x = t be the position of the pixel that has moved t pixels forward along the positive x-axis from the origin, and y = s be the position of the pixel that has moved s pixels forward along the y-axis from the origin. Select a certain t and observe the pixel value along the y-axis of the normalized image x = t (the pixel value in the normalized image in (1) above). In the combination of pixels where the difference in gray level between adjacent pixels above and below in the y-axis direction is 30 or more, set the coordinates of the lower pixel as (t, m), the coordinates of the upper adjacent pixel as (t, m+1), and the lower pixel (t, m) as point (M) for recording. In addition, for each x coordinate t, if there are multiple points (M) above, record all points.

[0092] (4) Move the above t and perform the above operation (3) on all x. Generate a set of points (M) obtained from this. Denote the point (M) with the smallest y-coordinate among the points with the same x-coordinate in this set as point (m), and mark the coordinate as (t, m). t ). m t This represents the y-coordinate when x = t.

[0093] (5) Take the set of points (m) obtained in (4) above as set A. Connect the points (m) belonging to set A to form a temporary boundary line.

[0094] (6) Among the points (m) belonging to set A, select a point and set its coordinates as (p, mp). Among the points (m) belonging to set A, for the selected point, select two points with the first and second closest x-coordinates in the positive x-axis direction, and two points with the first and second closest x-coordinates in the negative x-axis direction. Take the moving average (m) of the y-coordinates of the five points formed by the selected point and these four points. p '), resulting in coordinates (p, m) p The point (m') is defined as follows: m' is located near the maximum or minimum value of p along the x-axis, and there are no two points in the positive or negative x-axis directions mentioned above. p That is, m p . Perform the same operation on all points (m) belonging to set A to create a set A' consisting of points (m'). The number of points (m) belonging to set A is the same as the number of points (m') belonging to set A'.

[0095] (7) Among the points (m) belonging to set A, select a point and set its coordinates as (p, m). p Additionally, let the coordinates of the point (m) belonging to set A, whose x-coordinate is greater than p and is closest to p, be set as (p+q, m). p+q ). In m p With m p+qIf the difference is more than 10 pixels, then (m) p -m p The absolute value of (′) and (m) p+q -m p+q The absolute values ​​of (m') are compared. p -m p When the absolute value of ') is large, delete the coordinates (p, m) from set A. p The point when (m) p+q -m p+q When the absolute value of ') is large, delete the coordinates (p+q, m) from set A. p+q Let A be a set of points (m). Perform the same operation on all points (m) belonging to set A, and the resulting set is set B. Set B is the set obtained by deleting several points from the points constituting set A.

[0096] (8) Move x = n from the minimum x-coordinate of the points belonging to set B constructed in (7) above to the maximum x-coordinate. If the movement starts from n = 0 and there are no points in set B with x = n, set the coordinate of the point belonging to set B whose x-coordinate is less than n and closest to n as (n = 0, m = 0). n0 Let the coordinate of the point belonging to set B whose x-coordinate is greater than n and closest to n be (n1, m). n1 Let the y-coordinate of the line segment connecting these two points be m when the x-coordinate is n. n , will (n, m n Add the points from set B to set C. The resulting set is then set C. All points in set B obtained in (7) belong to set C.

[0097] (9) The set C obtained in (8) above is the boundary between the fracture part of the composite and the space outside the composite.

[0098] (Calculation of Y) Y is calculated in the following order (1) to (4). (1) The length of the boundary line between the fractured part and the space outside the composite body is determined by converting the number of pixels. Then, the length of the actual space is determined based on the length of the boundary line converted by the number of pixels. (2) In each x-coordinate of the above SEM image, determine the pixels 50 pixels above the boundary. These pixels are the pixels corresponding to the space outside the composite body at a height of 0.2 μm from the boundary. (3) Observe the pixel values ​​of the above pixels in the positive x-axis direction and measure the region D from the point where the pixel value increases by 7 levels or more (the point where the pixel value increases by 7 levels or more) to the point where the pixel value decreases by 7 levels or more (the point where the pixel value decreases by 7 levels or more). Find the entire region D from the minimum to the maximum x-coordinate, and determine the length of each region in pixels. Then, determine the actual length of the space based on the length of each region in pixels. (4) Extract regions D' from all the regions D above whose length (actual spatial length) is less than 0.1 μm, and add up the lengths of all extracted regions D'. Divide the total length by the length of the boundary line to calculate Y.

[0099] For SEM images 1–7 of the composite membrane obtained in Example 1, the length (μm) of the boundary line and the proportion Y of the portion from carbon nanotubes with a diameter of less than 0.1 μm were determined. The results are shown in Table 1. Y refers to the ratio of the length of the portion originating from carbon nanotubes with a diameter of less than 0.1 μm existing in the space outside the composite at a height of 0.2 μm from the boundary to the length of the boundary line. Specifically, it refers to the ratio of the length of the region located 50 pixels above the boundary and with a brightness level of 7 or higher to the length of the boundary line.

[0100] Table 1 image Length of the boundary line (μm) The proportion Y (%) of CNTs with a coarseness below 0.1 μm 1 2.04 18.91 2 1.32 20.98 3 1.16 23.84 4 0.69 19.05 5 1.01 20.88 6 1.21 22.97 7 1.35 17.37

[0101] According to Table 1, in all observed SEM images 1–7, X and Y satisfy the above equations (1), (1'), and (1'). Furthermore, the total length of the boundary lines in the observed SEM images 1–7 is 8.78 μm.

[0102] [Comparative Example 1] (Preparation of the composite) Using the same method as in Example 1, 10g of the above-mentioned carbon nanotube powder and 20g of silicone oil (Shin-Etsu silicone, KF-96-1000CS, dimethyl silicone oil) were added to the three rollers in small amounts and alternately while mixing, and the total amount was added over 20 minutes. After adding the full amount, without changing the mixing conditions, mix for another 10 minutes to obtain a uniform black composite. The resulting composite is in the form of multiple thin sheets, is dry, and can be more easily torn by external force compared to the composite of Example 1.

[0103] After obtaining SEM images c1 to c7 with 256 gray levels in the same manner as in Example 1, the boundary between the fractured part and the space outside the composite body, the length of the boundary line, and the Y are determined in the same manner as in Example 1.

[0104] Table 2 image Length of the boundary line (μm) The proportion Y (%) of CNTs with a coarseness below 0.1 μm C1 1.60 22.41 C2 2.03 0.00 C3 1.33 17.61 C4 1.83 15.66 C5 1.55 14.63 C6 2.05 14.08 C7 0.89 13.75

[0105] According to Table 2, in SEM images c2 and c4 to c7 of SEM images c1 to c7, X and Y do not satisfy the above equations (1), (1') and (1').

[0106] [Example 2] (Preparation of the resin composition) Polypropylene (produced by Prime polymer, J106MG) and the composite obtained in Example 1 were melt-blended using a twin-screw extruder until the proportion of carbon nanotubes was 0.10% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0107] [Examples 3-4] (Preparation of the resin composition) The polypropylene (produced by Prime polymer, J704UG) and the composite obtained in Example 1 were melt-blended using a twin-screw extruder until the proportion of carbon nanotubes was 0.10% or 0.30% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0108] [Examples 5-6] (Preparation of the resin composition) Polypropylene (manufactured by Nippon Polypropylene Co., Ltd., BC4BSW) and the composite obtained in Example 1 were melt-blended using a twin-screw extruder until the proportion of carbon nanotubes was 0.10% or 0.30% by mass relative to 100% by mass of the resin composition, thus obtaining granules of the resin composition.

[0109] [Example 7] (Preparation of the resin composition) The mixture of polypropylene and talc (85% by mass of polypropylene and 15% by mass of talc) and the composite obtained in Example 1 were melt-blended using a twin-screw extruder until the proportion of carbon nanotubes was 0.10% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0110] [Examples 8-9] (Preparation of the resin composition) The polyamide (nylon 6 (LIBORON, N150-300)) and the composite obtained in Example 1 were melt-blended using a twin-screw extruder until the proportion of carbon nanotubes was 0.10% or 0.30% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0111] [Examples 10-11] (Preparation of the resin composition) The composite obtained in Example 1 was melt-blended using a twin-screw extruder with polyamide (nylon 6 (Toray manufactured, S133)) until the proportion of carbon nanotubes was 0.10% or 0.30% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0112] [Example 12] (Preparation of the resin composition) The polyamide (nylon 12 (Prime polymer, a8925) and the composite obtained in Example 1 were melt-blended using a twin-screw extruder until the proportion of carbon nanotubes was 0.10% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0113] [Examples 13-14] (Preparation of the resin composition) The composite obtained in Example 1 was melt-blended using a twin-screw extruder until the proportion of carbon nanotubes was 0.10% or 0.30% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0114] [Example 15] (Preparation of the resin composition) The composite obtained in Example 1 was melt-blended using a twin-screw extruder with recycled polypropylene (a mixture of four types of waste materials (polypropylene) from automotive parts) until the proportion of carbon nanotubes was 0.10% by mass relative to 100% by mass of the resin composition, resulting in granules of the resin composition.

[0115] [Comparative Examples 2-10] Except that the composite obtained in Example 1 was not used in Examples 2-15, the resin particles were obtained in the same manner as in each example.

[0116] [Tension Test] The obtained granules were injection molded using an injection molding machine (manufactured by Toyo Kikaku Metal Co., Ltd., PLASTARSI-100V (injection molding unit: F200HC) (barrel temperature: 230°C, mold temperature: 50°C in Examples 2, 3, 4, 5, 6, 7, 15 and Comparative Examples 2, 3, 4, 5, 10); (barrel temperature: 260°C, mold temperature: 40°C in Examples 8, 9, 10, 11 and Comparative Examples 6, 7); (barrel temperature: 210°C, mold temperature: 35°C in Examples 12, 13, 14 and Comparative Examples 8, 9) to produce dumbbell-shaped test pieces (test pieces for tensile testing) according to JIS K7162-1994. Tensile tests were performed using the above-mentioned dumbbell-shaped test pieces to evaluate the tensile modulus of elasticity (MPa), tensile strength (MPa), and strain at break (%).

[0117] [Bending Test] The obtained granules were injection molded using an injection molding machine (manufactured by Toyo Kikaku Metal Co., Ltd., PLASTARSI-100V (injection molding unit: F200HC) (barrel temperature: 230°C, mold temperature: 50°C in Examples 2, 3, 4, 5, 6, 7, 15 and Comparative Examples 2, 3, 4, 5, 10); (barrel temperature: 260°C, mold temperature: 40°C in Examples 8, 9, 10, 11 and Comparative Examples 6, 7); (barrel temperature: 210°C, mold temperature: 35°C in Examples 12, 13, 14 and Comparative Examples 8, 9). Cut test pieces (bending test pieces) were prepared according to JIS K7162 IBA (ISO 527-2). Bending tests were performed on the cut test pieces according to ISO 178 to evaluate the flexural modulus of elasticity (MPa).

[0118] [Charpy Impact Strength] The obtained granules were injection molded using an injection molding machine (manufactured by Toyo Kikaku Metal Co., Ltd., PLASTARSi-100V (injection molding unit: F200HC) (barrel temperature: 230°C, mold temperature: 50°C in Examples 2, 3, 4, 5, 6, 7, 15 and Comparative Examples 2, 3, 4, 5, 10); (barrel temperature: 260°C, mold temperature: 40°C in Examples 8, 9, 10, 11 and Comparative Examples 6, 7); (barrel temperature: 210°C, mold temperature: 35°C in Examples 12, 13, 14 and Comparative Examples 8, 9) to produce notched multifunctional test pieces (Charpy impact test pieces) according to JIS K7111. The Charpy impact strength (kJ / m²) was evaluated according to JIS K7111. 2 ). The evaluation results are shown in Tables 3-5.

[0119] Table 3

[0120] Table 4

[0121] Table 5

[0122] The "-" in the table indicates that the property was not detected.

[0123] As can be confirmed from Tables 3 to 5 above, the mechanical properties of the resin composition containing the composite of this disclosure are significantly improved. However, when the composite obtained in Example 1 was replaced with the composite obtained in Comparative Example 1, no significant improvement in mechanical properties was observed.

Claims

1. A composite comprising carbon nanotubes and a dispersant, wherein, Let X (mass%) be the content of the carbon nanotubes relative to 100% of the composite, and Y (%) be the following proportion. In more than 80% of the images taken under the condition that the total length of the boundary lines is more than 7.0 μm and less than 9.0 μm, X and Y satisfy the following formula (1): 0.5X≤Y≤0.8X (1) Ratio: For the fractured sample obtained by breaking the composite sample, an image is obtained using a scanning electron microscope (SEM). The image contains the boundary between the fractured portion of the fractured sample and the space outside the composite, with the length of the continuous boundary line being greater than 0.6 μm and less than 2.1 μm in each image. In this case, the ratio of the length of the portion from carbon nanotubes with a thickness of less than 0.1 μm at a height of 0.2 μm from the boundary to the length of the boundary line is obtained.

2. The composite as claimed in claim 1, wherein, The mass ratio of carbon nanotube content to dispersant content (carbon nanotube: dispersant) is 1:0.5 to 1:

10.

3. The composite as claimed in claim 1, wherein, The dispersant is an organosilicon-based dispersant.

4. The composite as claimed in claim 1, wherein, It is membranous.

5. A resin composition comprising the composite of claim 1 and a resin.

6. The resin composition of claim 5, wherein, The resin is at least one selected from thermoplastic resins and thermosetting resins.

7. The resin composition of claim 5, wherein, It also contains inorganic fillers.

8. A method for manufacturing a composite, It is a method for manufacturing a composite containing carbon nanotubes and a dispersant. It has a process of using three rollers to mix the carbon nanotubes and the dispersant. Let X (mass%) be the content of the carbon nanotubes relative to 100% of the composite, and Y (%) be the following proportion. In more than 80% of the images taken under the condition that the total length of the boundary lines is more than 7.0 μm and less than 9.0 μm, X and Y satisfy the following formula (1): 0.5X≤Y≤0.8X (1) Ratio: For the fractured sample obtained by breaking the composite sample, an image is obtained using a scanning electron microscope (SEM). The image contains the boundary between the fractured portion of the fractured sample and the space outside the composite, with the length of the continuous boundary line being greater than 0.6 μm and less than 2.1 μm in each image. In this case, the ratio of the length of the portion from carbon nanotubes with a thickness of less than 0.1 μm at a height of 0.2 μm from the boundary to the length of the boundary line is obtained.

Images