Adhesion separation method for fibrous carbon nanohorn aggregate

Abstract

To provide a method for separating a fibrous carbon nanohorn aggregate.SOLUTION: An adhesion separation method for a fibrous carbon nanohorn aggregate according to one aspect of the present disclosure includes: providing a dispersion liquid including a carbon nanohorn aggregate mixture containing a fibrous carbon nanohorn aggregate onto a substrate having on a surface thereof an intermediate layer having a functional group that enhances adhesion to the fibrous carbon nanohorn aggregate; and moving at least one of the dispersion liquid on the intermediate layer and the substrate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for separating and adhering fibrous carbon nanohorn aggregates. [Background technology]

[0002] A single-walled carbon nanohorn is a cone-shaped carbon structure in which a graphene sheet is rolled up and the tip is sharpened to a horn shape with a tip angle of approximately 20°. Typically, single-walled carbon nanohorns assemble radially with the conical tip facing outward, forming a spherical carbon nanohorn aggregate with a diameter of approximately 100 nm.

[0003] Furthermore, in recent years, fibrous carbon nanohorn aggregates have been discovered, which differ from spherical carbon nanohorn aggregates in that single-walled carbon nanohorns are radially aggregated and have an extended fibrous structure. Patent Document 1 describes fibrous carbon nanohorn aggregates. Because fibrous carbon nanohorn aggregates have properties such as high dispersibility and high conductivity, they are expected to be used as conductive materials for lithium-ion batteries, electrodes for high-capacity electric double-layer capacitors, polymer actuator electrodes, sensor electrodes, catalyst supports, composite materials, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6179678 Summary of the Invention [Problem to be solved by the invention]

[0005] Fibrous carbon nanohorn aggregates (also known as "carbon nanobrushes," also referred to as "CNBs" in this specification) are produced by laser ablation of an iron-containing carbon target, but at the same time, large amounts of spherical carbon nanohorn aggregates (also referred to as "CNHs"), at 80% or more, and approximately 10-15% graphite and carbon fragments are also produced. Because the content of fibrous carbon nanohorn aggregates in the product is only a few percent, the carbon nanobrushes must be separated and purified from other products in order to evaluate the properties and use them themselves.

[0006] Graphite and carbon fragments can be separated by settling them in a dispersion liquid because they differ in size and density from carbon nanohorn aggregates. However, because spherical carbon nanohorn aggregates and fibrous carbon nanohorn aggregates have similar diameters (approximately 0.1 μm) and similar properties such as density and catalyst content, it has been difficult to separate only the fibrous carbon nanohorn aggregates.

[0007] In view of the above-mentioned problems, an object of the present invention is to provide a method for separating fibrous carbon nanohorn aggregates. [Means for solving the problem]

[0008] The inventors have found that there is a difference in adhesive strength to a substrate or the like between spherical carbon nanohorn aggregates (CNHs) and fibrous carbon nanohorn aggregates (CNBs). They have also found that by utilizing this difference in adhesive strength, fibrous carbon nanohorn aggregates can be separated. The present invention is based on this finding and includes the following aspects.

[0009] One aspect of the present disclosure is A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates on a substrate having an intermediate layer on the surface thereof having functional groups that enhance adhesion to the fibrous carbon nanohorn aggregates; a step of moving at least one of the dispersion liquid on the intermediate layer and the substrate; The present invention relates to a method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

[0010] One aspect of the present disclosure is A step of creating defects in the fibrous carbon nanohorn aggregates, modifying them with functional groups that increase adhesion to a substrate, and / or binding them with a compound that increases adhesion to a substrate; A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates in which defects have been created by the above step, or which have been modified with a functional group that increases adhesion to the substrate, and / or to which a compound that increases adhesion to the substrate has been bonded, on a substrate; moving at least one of the dispersion on the substrate and the substrate; The present invention relates to a method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

[0011] One aspect of the present disclosure is A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates on a substrate by spraying the dispersion liquid in an aerosol state. The present invention relates to a method for adhering and separating fibrous carbon nanohorn aggregates, comprising: [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for separating fibrous carbon nanohorn aggregates from a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates. [Brief explanation of the drawings]

[0013] [Figure 1] This is an SEM image of a carbon nanohorn aggregate mixture (graphite removed) dispersion liquid dropped onto a substrate and then dried. [Figure 2] Schematic diagrams of spherical carbon nanohorn aggregates (CNHs) (left) and fibrous carbon nanohorn aggregates (CNB) (right), and a schematic diagram showing the adhesive portion between them and the substrate. [Figure 3]FIG. 2 is a schematic diagram showing aerosol droplets of a carbon nanohorn aggregate mixture dispersion liquid. [Figure 4A] 1 is an SEM image of CNB / CNHs adhesion on an intermediate layer (APTES) in Example 1. [Figure 4B] 1 is an SEM image of CNB / CNHs adhesion on an intermediate layer (APTES) in Example 2. [Figure 5] 10 is an SEM image of CNB / CNHs monodisperse adhesion when an aerosol of a carbon nanohorn aggregate mixture dispersion in Example 12 is sprayed onto an intermediate layer (APTES). DETAILED DESCRIPTION OF THE INVENTION

[0014] Fibrous carbon nanohorn aggregates (CNB) and spherical carbon nanohorn aggregates (CNHs) share many similar properties and possess similar protruding horns. However, spherical carbon nanohorn aggregates have horns radiating from a central point, while fibrous carbon nanohorn aggregates have test-tube brush-like horns extending from a centerline. Therefore, as shown in Figure 2, the proportion and number of horns that can contact a flat surface are greater in fibrous carbon nanohorn aggregates. The horns of spherical and fibrous carbon nanohorn aggregates contain many five- and seven-membered rings, which are highly reactive and contribute to their adhesion to substrates. Therefore, fibrous carbon nanohorn aggregates with a greater proportion and number of horns exhibit higher adhesion to substrates. The present invention utilizes these structural differences, resulting in differences in their adhesiveness to flat surfaces, to separate the two.

[0015] In the present invention, separating the fibrous carbon nanohorn aggregates includes not only separating the fibrous carbon nanohorn aggregates themselves but also increasing the ratio of the fibrous carbon nanohorn aggregates in a mixture containing the fibrous carbon nanohorn aggregates. Furthermore, the method for separating fibrous carbon nanohorn aggregates of the present invention includes a method of adhering the fibrous carbon nanohorn aggregates alone or a mixture with an increased ratio of fibrous carbon nanohorn aggregates to a substrate. In this specification, the term "adhesion separation method" refers to a method of separating fibrous carbon nanohorn aggregates by adhering a mixture containing fibrous carbon nanohorn aggregates to a desired substrate.

[0016] The following describes embodiments of the present invention. However, although the embodiments described below have technically preferable limitations for carrying out the present invention, they do not limit the scope of the invention to the following.

[0017] <Fibrous carbon nanohorn aggregates> Fibrous carbon nanohorn aggregates, also known as carbon nanobrushes (CNBs), have a structure in which single-walled carbon nanohorns are radially aggregated and connected in a fibrous form. Unlike single-walled carbon nanohorn aggregates that simply appear fibrous, fibrous carbon nanohorn aggregates can maintain their fibrous shape even after centrifugal separation, ultrasonic dispersion, and other processes. Single-walled carbon nanohorns are conical carbon structures with a diameter of 1 nm to 5 nm and a length of 30 nm to 100 nm, each of which has a structure in which a graphene sheet is wound and the tip is sharpened to a horn-like shape with a tip angle of approximately 20°. Here, the carbon structure refers to a structure primarily containing carbon and may also contain light elements and catalytic metals. Fibrous carbon nanohorn aggregates are fibrous carbon structures, generally with a diameter of 30 nm to 200 nm and a length of 0.2 μm to 100 μm, e.g., 0.5 μm to 10 μm. The aspect ratio (length / diameter) of the fibrous carbon nanohorn aggregate is generally 4 to 4000, for example, 5 to 3500. The surface of the fibrous carbon nanohorn aggregate has single-walled carbon nanohorn protrusions with a diameter of 1 nm to 5 nm and a length of 30 nm to 100 nm. The fibrous carbon nanohorn aggregate has high conductivity because it is characterized by a structure in which highly conductive single-walled carbon nanohorns are connected in a fibrous form and have long conductive paths. Furthermore, the fibrous carbon nanohorn aggregate also has high dispersibility, making it highly effective at imparting conductivity.

[0018] Fibrous carbon nanohorn aggregates are formed by connecting seed-type, bud-type, dahlia-type, petal-dahlia-type, and petal-type (graphene sheet structure) carbon nanohorn aggregates. In other words, one or more types of carbon nanohorn aggregates are contained within the fibrous structure. The seed-type aggregate has few or no angular protrusions on its surface, the bud-type aggregate has a few angular protrusions on its surface, the dahlia-type aggregate has many angular protrusions on its surface, and the petal-type aggregate has petal-like protrusions on its surface. The petal structure has a width of 50 nm to 200 nm, a thickness of 0.34 nm to 10 nm, and a structure of 2 to 30 graphene sheets. The petal-dahlia type is an intermediate structure between the dahlia type and the petal type. The morphology and particle size of the resulting carbon nanohorn aggregates vary depending on the type and flow rate of the gas.

[0019] Fibrous carbon nanohorn aggregates are also described in detail in WO 2016 / 147909. Transmission electron microscope photographs of fibrous carbon nanohorn aggregates are disclosed in Figures 1 and 2 of WO 2016 / 147909. In the fibrous carbon nanohorn aggregates shown in these transmission electron microscope photographs, radially assembled single-walled carbon nanohorns (carbon nanohorn aggregates) are connected in a fibrous form. The entire disclosure of WO 2016 / 147909 is incorporated herein by reference.

[0020] <Carbon nanohorn aggregate mixture> The separation method of the present invention is a method for separating fibrous carbon nanohorn aggregates from a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates (hereinafter also simply referred to as a "carbon nanohorn aggregate mixture"). Preferably, the carbon nanohorn aggregate mixture is a mixture containing fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates. In one embodiment, the carbon nanohorn aggregate mixture is a carbon mixture produced when producing fibrous carbon nanohorn aggregates by a laser ablation method or the like described below. Preferably, the carbon nanohorn aggregate mixture is a mixture mainly composed of fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates obtained by removing graphite and the like from such a carbon mixture.

[0021] The content of fibrous carbon nanohorn aggregates in the carbon nanohorn aggregate mixture can be changed by changing the production conditions, but is preferably 2% by volume or more, and more preferably 4% by volume or more. The content of fibrous carbon nanohorn aggregates can be measured, for example, by particle size distribution measurement using dynamic light scattering, which measures the content ratio of fibrous carbon nanohorn aggregates to spherical carbon nanohorn aggregates. When the carbon nanohorn aggregate mixture contains graphite, it can be combined with thermogravimetric analysis to measure the graphite content.

[0022] Furthermore, the number ratio of fibrous carbon nanohorn aggregates (CNB) to spherical carbon nanohorn aggregates (CNHs) in the carbon nanohorn aggregate mixture ("CNB / CNHs ratio") is preferably 0.0005 or more, more preferably 0.001 or more, and although there is no particular upper limit, it is generally 0.005 or less, for example, 0.003 or less. The CNB / CNHs ratio can be measured, for example, by applying a dispersion of the carbon nanohorn aggregate mixture to a substrate and counting the number of fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates in the carbon nanohorn aggregate mixture, or by converting the volume ratio of the fibrous carbon nanohorn aggregates to the spherical carbon nanohorn aggregates based on particle size distribution measurement by dynamic light scattering to a number ratio.

[0023] <Preparation of carbon nanohorn aggregate mixture> A carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates can be produced by a laser ablation method or the like. In the laser ablation method, catalyst-containing carbon is used as a target (referred to as a catalyst-containing carbon target), and the catalyst-containing carbon target is heated and evaporated by laser ablation in a nitrogen atmosphere, an inert atmosphere, hydrogen, carbon dioxide, or a mixed atmosphere while rotating in a container in which the target is placed. Fibrous carbon nanohorn aggregates are obtained as the evaporated carbon and catalyst cool. In addition to the laser ablation method, carbon mixtures produced by arc discharge or resistance heating can also be used as the carbon nanohorn aggregate mixture in the present invention. However, the laser ablation method is more preferred from the viewpoint of continuous production at room temperature and atmospheric pressure.

[0024] The laser ablation method applied in the present invention is a method in which a target is irradiated with laser light in pulses or continuously, and when the irradiation intensity reaches a threshold value or higher, the target converts energy, resulting in the generation of a plume, and the product is deposited on a substrate located downstream of the target, or is generated in the space within the device and collected in a collection chamber.

[0025] For laser ablation, CO2 lasers, YAG lasers, excimer lasers, semiconductor lasers, etc. can be used, but CO2 lasers are the most suitable because they can be easily made high-power. CO2 lasers have a power output of 1kW / cm 2 ~1000kW / cm 2 An output of 1000 kW can be used, and it can be performed by continuous irradiation or pulse irradiation. Continuous irradiation is preferable for generating fibrous carbon nanohorn aggregates. The laser light is focused using a ZnSe lens or the like and then irradiated. Continuous synthesis is also possible by rotating the target. The target rotation speed can be set as desired, but 0.1 rpm to 6 rpm is particularly preferable. If it is 0.1 rpm or higher, graphitization can be suppressed, and if it is 6 rpm or lower, the increase in amorphous carbon can be suppressed. In this case, the laser output is 15 kW / cm 2 More than 30kW / cm is preferable. 2 ~300kW / cm 2 The most effective laser power is 15 kW / cm 2 If the laser output is 300 kW / cm or more, the target vaporizes appropriately, making it easy to generate fibrous carbon nanohorn aggregates. 2 If the pressure is below this, the increase in amorphous carbon can be suppressed. The pressure inside the vessel (chamber) can be used at 13,332.2 hPa (10,000 Torr) or less, but the closer the pressure is to a vacuum, the easier it is for carbon nanotubes to be produced, and fibrous carbon nanohorn aggregates cannot be obtained. The pressure inside the vessel (chamber) is preferably 666.61 hPa (500 Torr) to 1,266.56 hPa (950 Torr), and more preferably near atmospheric pressure (1013 hPa (1 atm ≒ 760 Torr)), which is suitable for mass synthesis and low cost. The irradiation area can also be controlled by the laser output and the degree of focusing with the lens, and can be adjusted to 0.005 cm. 2 ~1cm 2 can be used.

[0026] The catalyst can be Fe, Ni, or Co, either singly or in combination. The catalyst concentration can be selected as appropriate, but is preferably 0.1% by mass to 10% by mass, and more preferably 0.5% by mass to 5% by mass, relative to carbon. A concentration of 0.1% by mass or more ensures the generation of fibrous carbon nanohorn aggregates. Furthermore, a concentration of 10% by mass or less can suppress increases in target costs.

[0027] The temperature inside the vessel can be set at any desired temperature, preferably 0°C to 100°C, and more preferably room temperature, which is suitable for mass synthesis and cost reduction.

[0028] The above atmosphere is created by introducing nitrogen gas, inert gas, hydrogen gas, CO2 gas, etc., either alone or in combination, into the reactor. From the standpoint of cost, nitrogen gas and Ar gas are preferred. These gases are circulated within the reactor, and the generated substances can be recovered from this gas flow. Any atmospheric gas flow rate can be used, but a range of 0.5 L / min to 100 L / min is preferable. The gas flow rate is controlled to a constant value during the target evaporation process.

[0029] Through the above reaction, the carbon nanohorn aggregate mixture is usually obtained as a carbon mixture of fibrous carbon nanohorn aggregates, spherical carbon nanohorn aggregates of approximately uniform size with a diameter of about 30 nm to 200 nm, graphite particles of 1 μm to several tens of μm, and carbon pieces.

[0030] ·Catalyst removal The catalytic metal contained during the production of the carbon nanohorn aggregate mixture can be removed as needed. The catalytic metal can be removed because it dissolves in nitric acid, sulfuric acid, or hydrochloric acid. From the viewpoint of ease of use, hydrochloric acid is suitable. The temperature for dissolving the catalyst can be selected as appropriate, but to thoroughly remove the catalyst, it is desirable to heat the mixture to 70°C or higher. The timing of catalyst removal is not particularly limited. For example, when using nitric acid or sulfuric acid, catalyst removal and the creation of defects (formation of openings), which will be described later, can be performed simultaneously or successively. In addition, since the catalyst may be covered with a carbon film during the production of the carbon nanohorn aggregate mixture, it is desirable to perform pretreatment to remove the carbon film. Pretreatment is desirable, with heating in air at approximately 250°C to 450°C. At temperatures above 300°C, some openings may be formed.

[0031] Graphite removal Graphite can be removed from the carbon mixture obtained by the above-mentioned laser ablation method, etc., if necessary. Specifically, the carbon mixture is dispersed in an organic solvent, and the graphite is separated by settling. When the carbon mixture is dispersed in an organic solvent, the graphite settles. On the other hand, the fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates float due to their low density. By recovering the supernatant of the dispersion together with the floating solids, the graphite and the carbon nanohorn aggregates (fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates) can be separated. For further processing in other steps, the solvent is preferably removed from the recovered supernatant. The method for removing the solvent is not particularly limited, and the solvent may be removed, for example, by heat.

[0032] The organic solvent preferably has a density lower than that of graphite. The density of the organic solvent is preferably less than 1 g / cm 3 less than 0.8 g / cm 3The concentration is less than 100%. Examples of such organic solvents include ethanol and 2-propanol. It is difficult to separate graphite from solvents with relatively high density, such as aqueous solvents. The dispersion can be prepared, for example, by ultrasonic dispersion. The obtained dispersion is allowed to stand or is centrifuged to precipitate only the graphite, and the solid content floating in the dispersion is recovered, yielding a carbon nanohorn aggregate mixture from which the graphite has been removed. There are no particular limitations on the timing of the graphite removal step, but it is preferably performed before the separation step described below.

[0033] <Carbon nanohorn aggregate mixture dispersion> In the separation method of the present disclosure, a dispersion liquid in which the above-mentioned carbon nanohorn aggregate mixture is dispersed in a dispersion medium (hereinafter also referred to as "carbon nanohorn aggregate mixture dispersion liquid" or simply "dispersion liquid") can be used.

[0034] As the dispersion medium for the dispersion liquid, any of an organic solvent, an aqueous solvent, and a mixed solvent of an organic solvent and an aqueous solvent can be used.

[0035] Examples of the organic solvent include ethanol, 2-propanol, methyl ethyl ketone, toluene, and dichloroethane.

[0036] As the aqueous solvent, in addition to water, a surfactant solution in which a surfactant is added to water, phosphate buffered saline, etc. may be used. When a carbon nanohorn aggregate mixture is dispersed in a surfactant solution, the surfactant adheres to the periphery of the monodispersed fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates, forming micelles. The spherical carbon nanohorn aggregates and fibrous carbon nanohorn aggregates are dispersed in the surfactant solution, with almost no precipitation.

[0037] The surfactant may be any surfactant that spreads in the form of a film on the carbon nanohorn aggregates to prevent aggregation of the carbon nanohorn aggregates. Examples of surfactants include nonionic surfactants and ionic surfactants such as sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfate (SDBS), sodium cholate (SC), and sodium deoxycholate (DOC). In one embodiment, it is preferable to use a nonionic surfactant.

[0038] The nonionic surfactant can be selected appropriately, but it is preferable to use one or a combination of nonionic surfactants composed of a non-ionizable hydrophilic portion and a hydrophobic portion such as an alkyl chain, such as a nonionic surfactant having a polyethylene glycol structure, such as a polyoxyethylene alkyl ether, or an alkyl glucoside-based nonionic surfactant. Suitable examples of such nonionic surfactants include polyoxyethylene alkyl ethers (e.g., Brij (trademark)) represented by the following formula (1). The alkyl portion may contain one or more unsaturated bonds.

[0039] C n H 2n+1 (OCH2CH2) m OH (1) (wherein n is preferably 12 to 18, and m is 10 to 100, preferably 20 to 100)

[0040] In one embodiment, nonionic surfactants defined as polyoxyethylene (n) alkyl ethers (n is 20 to 100, alkyl chain length is C12 to C18), such as polyoxyethylene (23) lauryl ether, polyoxyethylene (20) cetyl ether, polyoxyethylene (20) stearyl ether, polyoxyethylene (10) oleyl ether, polyoxyethylene (10) cetyl ether, polyoxyethylene (10) stearyl ether, polyoxyethylene (20) oleyl ether, and polyoxyethylene (100) stearyl ether, are more preferred. N,N-bis[3-(D-gluconamido)propyl]deoxycholamide, n-dodecyl β-D-maltoside, octyl β-D-glucopyranoside, and digitonin can also be used.

[0041] Examples of nonionic surfactants include polyoxyethylene sorbitan monostearate (molecular formula: C 64 H 126 O 26 , trade name: Tween 60, manufactured by Sigma-Aldrich Co., Ltd.), polyoxyethylene sorbitan trioleate (molecular formula: C 24 H 44 O6, trade name: Tween 85, manufactured by Sigma-Aldrich Co., Ltd., etc.), octylphenol ethoxylate (molecular formula: C 14 H 22 O(C2H4O) n , n=1 to 10, product name: Triton X-100, manufactured by Sigma-Aldrich Co., Ltd., etc.), polyoxyethylene (40) isooctylphenyl ether (molecular formula: CH 17 C6H 40 (CH2CH 20 ) 40 H, product name: Triton X-405, manufactured by Sigma-Aldrich Co., Ltd., etc.), poloxamer (molecular formula: CH 10 O2, trade name: Pluronic, manufactured by Sigma-Aldrich, etc.), polyvinylpyrrolidone (molecular formula: (C6H9NO) n , n=5 to 100, manufactured by Sigma-Aldrich Co., etc.) can also be used.

[0042] The surfactant concentration can be appropriately set depending on the compound used, but is generally equal to or greater than the critical micelle concentration, preferably greater than the critical micelle concentration, for example, preferably 0.001% by mass or greater, more preferably 0.01% by mass or greater, and preferably 10% by mass or less, more preferably 5% by mass or less. In this specification, the critical micelle concentration (CMC) refers to the concentration at which the surface tension is measured at a constant temperature by varying the concentration of the surfactant aqueous solution using a surface tensiometer such as a Wilhelmy surface tensiometer. In this specification, the "critical micelle concentration" refers to the value at atmospheric pressure and 25°C.

[0043] The content of the carbon nanohorn aggregate mixture in the carbon nanohorn aggregate mixture dispersion is preferably 10 μg / ml or more, more preferably 100 μg / ml or more, and is preferably 100 mg / ml or less, more preferably 10 mg / ml or less.

[0044] Furthermore, as will be explained in the separation step described later, when the carbon nanohorn aggregate mixture is adhered to the substrate in a monodispersed state, the content of the carbon nanohorn aggregate mixture in the dispersion may be made smaller; for example, the content of the carbon nanohorn aggregate mixture in the carbon nanohorn aggregate mixture dispersion is preferably 1 mg / ml or less, and more preferably 0.5 mg / ml or less.

[0045] The carbon nanohorn aggregate mixture dispersion can be prepared by adding the carbon nanohorn aggregate mixture to a dispersion medium and dispersing it. It is preferable to perform ultrasonic treatment to improve the dispersibility of the carbon nanohorn aggregate mixture.

[0046] <Base material> The substrate to which the carbon nanohorn aggregate mixture is adhered is not particularly limited, and for example, any substrate or film can be used.

[0047] The materials for the substrate and film are not particularly limited, and examples include inorganic materials such as Si, SiO2-coated Si, SiO2, SiN, glass, and metals such as silver, titanium, and gold, as well as organic materials such as parylene, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, acrylonitrile styrene resin, acrylonitrile butadiene styrene resin, fluororesin, methacrylic resin, and polycarbonate.

[0048] <Separation method> The method for separating fibrous carbon nanohorn aggregates of the present disclosure is an adhesion separation method that utilizes the difference in adhesiveness between fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates to a substrate, and includes at least one of the following separation methods. It is also preferable to use a combination of two or more of the following methods.

[0049] (Method A) One aspect of the adhesion / separation method of the present disclosure includes: Providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates on a substrate; moving at least one of the dispersion on the substrate and the substrate; Includes. Fibrous carbon nanohorn aggregates have more horn portions in contact with flat surfaces than spherical carbon nanohorn aggregates, and therefore tend to remain on the substrate. On the other hand, spherical carbon nanohorn aggregates, which have fewer horn portions in contact with flat surfaces, tend to peel off relatively easily from the substrate. Moving at least one of the dispersion and the substrate (moving the dispersion relative to the substrate) suppresses adhesion of the spherical carbon nanohorn aggregates to the substrate and / or makes it easier for the spherical carbon nanohorn aggregates adhered to the substrate to peel off. In this way, by moving the dispersion relative to the substrate, the difference in adhesion between the fibrous carbon nanohorn aggregates and the spherical carbon nanohorn aggregates to the substrate can be more effectively utilized, and separation performance (the ability to increase the proportion of fibrous carbon nanohorn aggregates) can be improved.

[0050] In this embodiment, it is sufficient that the dispersion liquid moves relative to the substrate, so the dispersion liquid may be moved, the substrate may be moved, or both the dispersion liquid and the substrate may be moved.

[0051] In addition, the dispersion and / or the substrate may be moved at the same time as the dispersion is provided on the substrate, or the dispersion and / or the substrate may be moved after the dispersion is provided on the substrate (after the dispersion and the substrate have come into contact).

[0052] The method for providing the dispersion liquid on the substrate is not particularly limited, and examples thereof include dripping the dispersion liquid onto the substrate, applying the dispersion liquid onto the substrate, immersing the substrate in a tank containing the dispersion liquid, and pouring the dispersion liquid onto the substrate.

[0053] The method for moving the dispersion liquid and / or the substrate is not particularly limited as long as the dispersion liquid on the substrate or the substrate in the dispersion liquid is brought into a state where it can move on the substrate, such as by pulling, shaking, applying centrifugal force, washing with a solvent, applying ultrasonic waves, vibrating, blowing, etc. Representative embodiments are exemplified below.

[0054] (1) The substrate and / or the dispersion liquid are moved at an accelerated rate. In this case, the acceleration is 5 m / s 2 More than 50m / s is preferable. 2 More preferably, 30,000 m / s or more 2 Preferably below 3000m / s 2 The following are more preferred: Examples of modes of accelerating movement include shaking off the dispersion liquid provided on the substrate, blowing off the dispersion liquid provided on the substrate, providing the dispersion liquid on a substrate placed at a desired tilt angle, and spraying the dispersion liquid onto the substrate with acceleration.

[0055] (2) The substrate and / or dispersion are moved by applying centrifugal force. In this case, the centrifugal acceleration is preferably 0.5×g or more, more preferably 5×g or more, and preferably 3000×g or less, more preferably 300×g or less. Examples of modes of moving by applying centrifugal force include moving the dispersion provided on the substrate using a device having a turntable that rotates around its axis, such as a spin coater, moving the dispersion onto a substrate attached to a rotating disk that rotates around its axis, or moving the substrate by placing it in a device that applies centrifugal force perpendicular to the substrate, such as a centrifuge, and introducing and moving the dispersion.

[0056] (3) The substrate and / or dispersion liquid is moved by a method other than accelerated movement, for example, at a constant speed. In this case, the speed is preferably 0.1 m / s or more, more preferably 1 m / s or more, and preferably 30,000 m / s or less, more preferably 3,000 m / s or less. Examples of moving at a constant speed include continuously providing the dispersion liquid onto the substrate, washing the dispersion liquid off the substrate with a solvent (examples of the solvent include the solvent used in the washing step described below), moving a substrate immersed vertically in the dispersion liquid up and down, moving a substrate immersed horizontally in the dispersion liquid back and forth or left and right (horizontal direction), and rotating a substrate immersed horizontally in the dispersion liquid in the horizontal direction.

[0057] (4) The substrate and / or the dispersion liquid is vibrated. In this case, the vibration frequency is preferably 5 Hz or more, more preferably 50 Hz or more, and is preferably 10 kHz or less, more preferably 1 kHz or less. Ultrasonic waves may also be applied. Examples of vibration modes include vibrating the substrate while it is in contact with the dispersion liquid, or applying vibration to the dispersion liquid in which the substrate is immersed.

[0058] It is also preferable to combine two or more types of movement. Examples of such a method include (4) immersing the substrate in the dispersion liquid, and (3) moving the substrate up and down while applying ultrasonic waves to the dispersion liquid, or (4) moving the substrate horizontally.

[0059] (Method B) One embodiment of the adhesion separation method of the present disclosure includes a step of providing a dispersion containing a carbon nanohorn aggregate mixture on a substrate having an intermediate layer on its surface having functional groups that enhance adhesion to fibrous carbon nanohorn aggregates.

[0060] An intermediate layer with functional groups that enhances adhesion to fibrous carbon nanohorn aggregates In this embodiment, an intermediate layer to which fibrous carbon nanohorn aggregates can easily adhere is formed on the surface of a substrate, and a carbon nanohorn aggregate mixture dispersion is provided on the intermediate layer. By using such an intermediate layer, the adhesion of the fibrous carbon nanohorn aggregates to the substrate can be improved. Such an intermediate layer also improves the adhesion of the spherical carbon nanohorn aggregates to the substrate, but the fibrous carbon nanohorn aggregates have a greater effect in improving adhesion because they have a larger number of horn portions that contribute to adhesion to the substrate. This increases the difference in adhesion between the fibrous carbon nanohorn aggregates and the spherical carbon nanohorn aggregates to the substrate, thereby improving separation efficiency.

[0061] The material for the intermediate layer is preferably a compound having both a partial structure that adheres to the substrate surface and a functional group that has high adhesiveness to the fibrous carbon nanohorn aggregates. Here, the adhesion between the fibrous carbon nanohorn aggregates and the functional group can be achieved not only by chemical bonding but also by various intermolecular interactions such as electrostatic interaction, surface adsorption, hydrophobic interaction, van der Waals force, and hydrogen bonding.

[0062] Examples of the partial structure in the intermediate layer material that adheres to the substrate surface include an alkoxysilyl group (SiOR), SiOH, a hydrophobic moiety or hydrophobic group, etc. Examples of the hydrophobic moiety or hydrophobic group include a methylene group (methylene chain) or alkyl group having 1 or more, preferably 2 or more, and preferably 20 or less, more preferably 10 or less carbon atoms.

[0063] Examples of functional groups in the intermediate layer material that have high adhesiveness to the fibrous carbon nanohorn aggregates include amino groups such as primary amino groups (-NH2), secondary amino groups (-NHR1), and tertiary amino groups (-NR1R2), ammonium groups (-NH4), carboxy groups (-COOH), hydroxy groups (-OH), carbonyl groups (-C(=O)-), imino groups (=NH), imide groups (-C(=O)-NH-C(=O)-), amide groups (-C(=O)NH-), sulfo groups (-SOH), ferrocenyl groups, epoxy groups, isocyanurate groups, isocyanate groups, ureido groups, sulfide groups, and mercapto groups.

[0064] The material for such an intermediate layer is not particularly limited, but may be, for example, a silane coupling agent. Examples of the silane coupling agent include: Silane coupling agents having an amino group and an alkoxysilyl group (aminosilane compounds), such as 3-aminopropyltrimethoxysilane, 3-aminopropylmethyltriethoxysilane, 3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane (APTES), 3-(2-aminoethyl)aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; silane coupling agents having an epoxy group and an alkoxysilyl group, such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyldiethoxysilane, and triethoxy(3-glycidyloxypropyl)silane; Isocyanurate-based silane coupling agents such as tris-(trimethoxysilylpropyl) isocyanurate; ureido-based silane coupling agents such as 3-ureidopropyltrialkoxysilane; mercapto-based silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane; Sulfide-based silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide; and Isocyanate-based silane coupling agents such as 3-isocyanatepropyltriethoxysilane; Examples include:

[0065] In particular, a silane coupling agent having an amino group (aminosilane compound) is preferred because of its good bonding property with the fibrous carbon nanohorn aggregates.

[0066] Other examples of materials for the intermediate layer include polymers (e.g., cationic polymers) having a partial structure that can adhere to the substrate and a partial structure that can adhere to the fibrous carbon nanohorn aggregates, and self-assembled monolayers (e.g., thiol derivatives, phosphonic acid derivatives).

[0067] Examples of such polymers include poly(N-methylvinylamine), polyvinylamine, polyallylamine, polyallyldimethylamine, polydiallylmethylamine, polydiallyldimethylammonium chloride, polydiallyldimethylammonium trifluoromethanesulfonate, polydiallyldimethylammonium nitrate, polydiallyldimethylammonium perchlorate, polyvinylpyridinium chloride, poly(2-vinylpyridine), poly(4-vinylpyridine), polyvinylimidazole, poly(4-aminomethylstyrene), poly(4-aminostyrene), polyvinyl(acrylamide-co-dimethylaminopropylacrylamide), polyvinyl(acrylamide-co-dimethylaminoethylmethyl)acrylate, polyvinyl(acrylamide-co-dimethylaminoethyl ... acrylate), polyethyleneimine (PEI), DAB-Am and polyamidoamine dendrimers, polyaminoamides, polyhexamethylene biguanide, polydimethylamine-epichlorohydrin, products of alkylation of polyethyleneimine with methyl chloride, products of alkylation of polyaminoamides with epichlorohydrin, cationic polyacrylamides with cationic monomers, formalin condensation products of dicyandiamide, dicyandiamide, polyalkylenepolyamine polycondensates, naturally-based cationic polymers (e.g., partially deacetylated chitin, chitosan, and chitosan salts), synthetic polypeptides (e.g., polyasparagine, polylysine, polyglutamine, and polyarginine).

[0068] Among these polymers, cationic polymers having an amino group and a hydrophobic group or a hydrophobic portion are preferred from the viewpoint of adhesiveness to the fibrous carbon nanohorn aggregates. An example of such a cationic polymer is polylysine.

[0069] A "self-assembled monolayer" refers to a molecular film that spontaneously forms with high orientation on the surface of a substrate through self-assembly. A self-assembled monolayer is preferably a compound having a functional group with high affinity for the substrate and a functional group capable of adhering to fibrous carbon nanohorn aggregates. The compound that forms the self-assembled monolayer can be selected appropriately depending on the substrate and is not particularly limited. However, for example, functional groups containing sulfur atoms are preferred from the standpoint of affinity for gold, silver, their alloys, and their plated metal surfaces. Furthermore, thiol derivatives containing a thiol group (-SH) are preferred from the standpoint of ease of handling and availability. The functional groups of the thiol derivative other than thiol are not particularly limited. Compounds that have excellent adhesive properties to fibrous carbon nanohorn aggregates include, but are not limited to, compounds having an amide group such as 10-Amido-1-decanethiol, 7-Amido-1-heptanethiol, and 5-Amido-1-penetanethiol; compounds having a carboxy group such as 15-Carboxy-1-pentadecanethiol, 10-Carboxy-1-decanethiol, 7-Carboxy-1-heptanethiol, and 5-Carboxy-1-pentanethiol; and compounds having a hydroxy group such as 16-Hydroxy-1-hexadecanethiol, 11-Hydroxy-1-undecanethiol, 8-Hydroxy-1-octanethiol, and 6-Hydroxy-1-hexanethiol.

[0070] In addition, when a material having an amino group as a functional group is used for the intermediate layer, the amino group may improve the adhesiveness of not only the fibrous carbon nanohorn aggregates but also the spherical carbon nanohorn aggregates to the substrate, and the separation performance may be reduced due to the difference in adhesiveness to the substrate. In such cases, it may be preferable to use a compound having a functional group other than an amino group for the intermediate layer. In such cases, preferred functional groups include, for example, an amide group, a carboxy group, and a hydroxy group.

[0071] The thickness of the intermediate layer can be appropriately set depending on the material used, but from the viewpoint of increasing the adhesive strength of the fibrous carbon nanohorn aggregates, it is preferably 1 nm or more, more preferably 2 nm or more. The upper limit is not particularly limited, but is, for example, 100 nm or less, preferably 50 nm or less, more preferably 10 nm or less.

[0072] Furthermore, the intermediate layer may increase the adhesiveness of not only the fibrous carbon nanohorn aggregates but also the spherical carbon nanohorn aggregates to the substrate. To prevent excessive residual spherical carbon nanohorn aggregates due to the improved adhesive strength of the intermediate layer, it may be more efficient to have a very small film thickness and density of the intermediate layer. In such cases, the thickness of the intermediate layer is preferably 0.1 nm or more, more preferably 0.2 nm or more. There is no particular upper limit, but it is, for example, 5 nm or less, preferably 2 nm or less, and more preferably 1 nm or less. Regarding the density of the intermediate layer, the intermediate layer may cover 100% of the substrate, or may be attached in a dotted or convex manner on the substrate. A dotted state on the substrate may be more efficient. In such cases, the area ratio (portion with intermediate layer / portion without intermediate layer) on the substrate is not limited, but is preferably, for example, 0.01 or more, and preferably 100 or less.

[0073] The above-mentioned method A and method B have the effect of separating fibrous carbon nanohorn aggregates even when used alone, but by combining these steps, that is, the adhesion separation method of the present invention is A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture on a substrate having an intermediate layer on the surface thereof having functional groups that enhance adhesion to the fibrous carbon nanohorn aggregates; a step of moving at least one of the dispersion liquid provided on the substrate and the substrate; It is particularly preferable to include both of the steps of: Forming an intermediate layer on the surface of the substrate to which nanocarbon easily adheres, and in addition, moving the dispersion liquid on the substrate having the intermediate layer, immersing the substrate in the dispersion liquid and moving it, or applying an external stimulus such as vibration, thereby further improving the separation of the fibrous carbon nanohorn aggregates and the spherical carbon nanohorn aggregates.

[0074] (Method C) An adhesion separation method according to one embodiment of the present disclosure includes providing, on a substrate, a dispersion liquid containing a carbon nanohorn aggregate mixture including fibrous carbon nanohorn aggregates that have been created with defects, modified with functional groups that enhance adhesion to the substrate, and / or bound with compounds that enhance adhesion to the substrate.

[0075] The horn parts of fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates contain many five-membered and seven-membered rings, making them highly reactive. When defects occur in these horn parts or when functional groups or compounds with high bonding and adhesive properties to the substrate are attached, the reactivity is further improved, and the adhesion to the substrate is improved. Compared to spherical carbon nanohorn aggregates, fibrous carbon nanohorn aggregates have a higher proportion and number of horn parts in contact with the substrate, so the introduction of defects, functional groups, compounds, etc. is more effective in improving adhesion. This increases the difference in adhesive strength between fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates, thereby improving separation efficiency.

[0076] A method for preparing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates having defects, desired functional groups, or desired compounds used in this embodiment will be described below. The introduction reaction of these defects, functional groups, or compounds can be carried out on the above-mentioned carbon nanohorn aggregate mixture.

[0077] Defect creation and functionalization processes Since the horn portion of the fibrous carbon nanohorn aggregate contains many five-membered and seven-membered rings, slight defects can be created on the horn surface by oxidation treatment without deteriorating the conductive properties. There are no particular restrictions on the method of such oxidation treatment, and either a gas-phase process or a liquid-phase process can be used.

[0078] In the case of a gas phase process, the process is carried out in a gas atmosphere such as oxygen, air, hydrogen peroxide, carbon dioxide, or carbon monoxide. The oxidation treatment temperature in the gas atmosphere is preferably 250 to 650°C, more preferably 300 to 500°C, and even more preferably 300 to 400°C. If the temperature is too low, oxidation is difficult to occur, while if the temperature is too high, oxidation occurs too quickly and becomes difficult to control. The treatment time can be adjusted as appropriate, but is preferably within the range of about 5 to 7 hours at a temperature rise rate of 1°C / min.

[0079] In the liquid-phase process, oxidation treatment is performed in a liquid containing an oxidizing substance such as nitric acid, sulfuric acid, a sulfuric acid-nitric acid mixed solution, hydrogen peroxide, or chloric acid. Oxidation treatment using these acids is performed at approximately 0°C to 180°C (any temperature at which the aqueous solution exists as a liquid) for aqueous solutions, or at a temperature at which the solvent used exists as a liquid for organic solvents. Nitric acid and sulfuric acid are preferably used at temperatures ranging from room temperature to 120°C. Hydrogen peroxide can be used at temperatures ranging from room temperature to 100°C, with 40°C or higher being more preferred. The oxidizing power works efficiently in the temperature range of 40 to 100°C. 50 to 80°C is particularly preferred. The treatment time can be adjusted as needed, but is preferably within a range of, for example, 0.5 to 3 hours. Furthermore, the liquid-phase process is more effective when light irradiation is used in combination.

[0080] Through the above oxidation treatment, functional groups such as carbonyl groups, carboxyl groups, hydroxyl groups, nitro groups, sulfone groups, phenol groups, oxygen-containing functional groups including ether bonds or ester bonds, or imino groups can be added to the five-membered rings, seven-membered rings, and other highly reactive carbon sites at the curved graphite surfaces, such as the tips of carbon nanohorns.

[0081] In one embodiment, it is preferable to perform the oxidation treatment weakly and not excessively. This is because oxidation begins with the highly reactive five-membered and seven-membered rings present in abundance at the tips, but excessive oxidation may cause the oxidation to progress further, resulting in the disappearance of the nanohorn tips and the inability to form caps with cyclodextrin, as described below. Furthermore, the nanohorn body may also be oxidized, generating holes and changing the bulk properties of the carbon nanohorn aggregate.

[0082] The degree of oxidation in this case is preferably 1.0 × 10 oxygen to the total carbon (100 atomic %). -5 Atomic%~1.0×10 0 atomic %, more preferably 1.0 × 10 -3 Atomic%~1.0×10 0 It is preferable to include oxygen at a ratio of atomic percent. The ratio of oxygen to carbon can be estimated by various analytical methods, for example, from the intensity ratio of O1s and C1s in X-ray photoelectron spectroscopy.

[0083] Cyclodextrin treatment The adhesiveness of the fibrous carbon nanohorn aggregates to the substrate can also be further improved by bonding the fibrous carbon nanohorn aggregates with a compound that enhances the adhesiveness to the substrate, such as cyclodextrin.

[0084] By treating the carbon nanohorn assembly mixture that has undergone the above-mentioned oxidation treatment with a cyclodextrin-containing solution, it is possible to produce a hydrophilic carbon nanohorn assembly mixture in which the nanohorn tips are capped with cyclodextrin. Because oxygen-containing functional groups have been introduced into the tips of the carbon nanohorn aggregates, they interact with the OH groups of the cyclodextrin, specifically by hydrogen bonding, thereby immobilizing and stabilizing the cyclodextrin.

[0085] Cyclodextrin (hereinafter sometimes abbreviated as "CD") is a cyclic oligosaccharide, a non-reducing sugar in which glucose residues are bonded in a ring via α-1,4 bonds, and has a torus structure, also known as a bottomless bucket or crown. The interior of cyclodextrin is hydrophobic, but the numerous OH groups on the exterior make it water-soluble.

[0086] Examples of cyclodextrins include well-known cyclodextrins, such as unsubstituted cyclodextrins containing 6 to 12 glucose units, particularly α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and / or their derivatives and / or mixtures thereof, depending on the number of glucose units constituting the cyclodextrin. α-cyclodextrin is composed of 6 glucose units, β-cyclodextrin is composed of 7 glucose units, and γ-cyclodextrin is composed of 8 glucose units, each with a different cavity size. In this embodiment, it is preferable to contain at least one cyclodextrin selected from the group consisting of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0087] The cyclodextrin treatment involves contacting the oxidized carbon nanohorn aggregate mixture with cyclodextrin in a solution that the cyclodextrin has been dissolved in. The dispersion medium used is water, or a dispersion medium containing, in addition to water, a surfactant, a water-soluble organic solvent, etc. as necessary.

[0088] The amount of cyclodextrin added can be selected appropriately, and is, for example, 0.1 to 50 parts by mass, and preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the carbon nanohorn aggregate mixture that has been subjected to the oxidation treatment. The treatment conditions are not particularly limited, but may be appropriately selected, for example, in the range of 0 to 100°C, preferably in the range of 10 to 70°C. In one embodiment, the temperature is preferably in the range of 15 to 60°C, which is close to room temperature. The treatment time may also be appropriately set, for example, 10 minutes or more, preferably 3 hours or more, and there is no particular upper limit, but the treatment may be carried out for, for example, 10 days or less.

[0089] As described above, the oxygen-containing functional groups at the tips of the carbon nanohorn aggregates and the hydroxyl groups of the cyclodextrin interact with each other, specifically, are fixed by hydrogen bonding, resulting in a stabilized hydrophilic carbon nanohorn aggregate mixture. The hydrophilicity obtained improves dispersibility in aqueous media.

[0090] The carbon nanohorn aggregate mixture obtained as described above, in which defects are created in the horn portion, modified with functional groups that increase adhesion to the substrate, and / or bound with compounds that increase adhesion to the substrate, is highly hydrophilic. Therefore, when preparing the carbon nanohorn aggregate mixture dispersion liquid described above, it has the advantage of being easily dispersed in an aqueous dispersion medium without the addition of a surfactant, and is easily monodispersed.

[0091] It is particularly preferable to combine the step of moving the dispersion liquid of the above-mentioned method A relative to the substrate with method C of this embodiment. This makes it possible to suppress adhesion of the spherical carbon nanohorn aggregates, which have weak adhesive strength to the substrate, to the substrate and / or to peel and remove the spherical carbon nanohorn aggregates adhered to the substrate.

[0092] It is also preferable to combine the step of providing an intermediate layer having predetermined functional groups on the surface of the substrate with the method C of this embodiment described above in the method B. By doing so, the difference in adhesive strength between the fibrous carbon nanohorn aggregates and the spherical carbon nanohorn aggregates becomes even greater, thereby further increasing the separation efficiency.

[0093] In one embodiment, when Method C is combined with Method A and Method B, the separation efficiency of the fibrous carbon nanohorn aggregates can be further increased.

[0094] (Method D) The separation and adhesion method of one embodiment of the present disclosure includes a step of providing a carbon nanohorn aggregate mixture dispersion liquid on a substrate by spraying it in an aerosol state.

[0095] When a carbon nanohorn aggregate mixture adheres to a substrate in an aggregated state, it is difficult to separate the fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates by utilizing the difference in adhesive strength to the substrate. In response to this problem, the inventors discovered that by converting a carbon nanohorn aggregate mixture dispersion into an aerosol, the fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates that are monodispersed in the dispersion can be sprayed while maintaining their monodispersed state. When this aerosol of the carbon nanohorn aggregate mixture is sprayed onto a substrate, the fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates can be provided on the substrate while remaining separated from each other in a monodispersed state, as shown in Figure 3. This makes it possible to separate the fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates by utilizing the difference in adhesive strength to the substrate.

[0096] In this specification, "adhering fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates in a monodispersed state" means a state in which the fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates are adhered to the substrate in a state in which they are separated into individual aggregates (i.e., a state in which two or more aggregates of fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates are not aggregated). In one embodiment, preferably 0.1% (number ratio) or more of the fibrous carbon nanohorn aggregates are in a monodispersed state, more preferably 1% (number ratio) or more are in a monodispersed state, and even more preferably 10% (number ratio) or more are in a monodispersed state. In one aspect, the upper limit of the ratio of monodispersed fibrous carbon nanohorn aggregates in the fibrous carbon nanohorn aggregates obtained by the adhesion / separation method of the present disclosure is not limited and may be 100% or, for example, 90% or less, 80% or less, or 70% or less. The ratio of the fibrous carbon nanohorn aggregates in a monodispersed state can be determined by applying a carbon nanohorn aggregate mixture dispersion liquid onto a substrate and counting the number of fibrous carbon nanohorn aggregates in a monodispersed state and the number of fibrous carbon nanohorn aggregates to which spherical carbon nanohorn aggregates are attached.

[0097] The size of the aerosol droplets is not particularly limited as long as each droplet can contain a fibrous carbon nanohorn aggregate, but the diameter of the outlet of the aerosol spray device is preferably 0.1 μm or more, more preferably 0.5 μm or more, because the outlet is less likely to be clogged with the dispersion.

[0098] Furthermore, from the viewpoint of providing fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates in a monodispersed state to a substrate and improving the separation performance of the two, a smaller droplet diameter is more effective. For example, the droplet diameter is preferably 100 nm or more, more preferably 500 nm or more, and preferably 50 μm or less, more preferably 10 μm or less. When the aerosol droplet diameter is small, the number of carbon nanohorn aggregates contained in each aerosol droplet is single or a small number, so that the aerosol droplets are provided on the substrate in a separated state. In addition, the solvent in the aerosol droplets dries faster, making aggregation on the substrate less likely to occur. The aerosol droplet diameter can be measured, for example, as D50 in the particle size distribution determined using a laser diffraction particle size distribution analyzer.

[0099] The aerosol density is not particularly limited, but the number of aerosol droplets per unit area when attached to the substrate is preferably 10 4 pieces / mm 2 More than 10, preferably 5 pieces / mm 2 From the viewpoint of maintaining monodispersity, it is preferably 10 8 pieces / mm 2 Less than or equal to 10, more preferably 7 pieces / mm 2 It is preferable to adjust the aerosol density so that:

[0100] The aerosol may be sprayed repeatedly or continuously, but it is preferable to spray next after the solvent of the aerosol droplets has dried on the substrate to avoid aggregation on the substrate. When the aerosol droplet size is small, the solvent dries quickly as described above, so the time interval between repeated sprays can be shortened.

[0101] In one embodiment, the aerosol droplets may be sprayed directly onto the substrate, or may be carried to the substrate by a constant-speed gas stream. The type of gas in the gas stream is not particularly limited, but air, nitrogen, argon, helium, or other gases that do not react with carbon nanohorn aggregates are preferred. Since the solvent in the aerosol droplets dries while they are moving in the gas stream, when the droplets reach the substrate, they can be supplied to the substrate in a state where the droplets have a smaller diameter, or as completely dried carbon nanohorn aggregates in a monodispersed state.

[0102] The orientation of the substrate when spraying the aerosol droplets, the direction in which the aerosol droplets are sprayed (spray direction), the spray angle (the spread angle of the liquid sprayed from the nozzle), and other factors are not limited. For example, the plane of the substrate may be horizontal, inclined relative to the horizontal, or vertical. The angle between the plane of the substrate and the spray direction of the droplets (e.g., the axial direction of the spray nozzle) may be any value between 90° (vertical) and 0° (horizontal). For example, the aerosol droplets may be supplied from above to below (e.g., vertically) the plane of a horizontally placed substrate. Alternatively, for example, the substrate may be set up so that its plane is vertical, and the aerosol droplets may be sprayed from the side (horizontally). The angle between the substrate and the spray direction of the aerosol droplets is not limited, and the angle between the plane of the substrate and the axial direction of the spray nozzle body may be any value between 90° (vertical) and 0° (horizontal), and can be appropriately selected. The spray angle when spraying the aerosol droplets (the angle at which the liquid sprayed from the nozzle spreads) is not limited, and may be, for example, about 30 to 160°, and preferably about 40 to 80°.

[0103] Because the aerosol droplets are sprayed with speed, they move relatively even when the substrate is not moved, and they can be separated due to the difference in adhesive strength between the fibrous carbon nanohorn aggregates and the spherical carbon nanohorn aggregates to the substrate.

[0104] Furthermore, in one embodiment, it is particularly preferable to move the aerosol droplets of the carbon nanohorn aggregate mixture dispersion and / or the substrate, that is, to combine the above method D with the above method A. When the aerosol droplets move relatively to the substrate, adhesion of spherical carbon nanohorn aggregate droplets, which have a small adhesive strength and contact area with the substrate, to the substrate can be suppressed, and / or the spherical carbon nanohorn aggregate droplets adhered to the substrate can be peeled off and removed. This makes it possible to combine the separation effect of adhering droplets to the substrate without connection / aggregation by aerosol spraying in method D with the separation effect due to the difference in adhesive strength between the fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates to the substrate, obtained by movement in method A, and further improve separation efficiency.

[0105] In this embodiment, since the aerosol droplets of the carbon nanohorn aggregate mixture dispersion and the substrate are moved relative to each other, the substrate may be moved, the aerosol droplets may be moved, or both may be moved. As the form of movement, the examples exemplified in Method A can be applied.

[0106] When the substrate is moved, the substrate may be moved simultaneously with the aerosol being sprayed, or may be moved after the aerosol droplets have contacted the substrate.

[0107] When moving aerosol droplets, it is possible to move aerosol droplets that adhere to a substrate. When spraying aerosol droplets, it is also possible to supply aerosol droplets to the substrate at different movement speeds by controlling the discharge pressure, etc. Furthermore, the separation efficiency can be improved by adjusting the angle between the substrate plane and the spray direction, the intermediate layer, the solvent, the concentration of the carbon nanohorn aggregate mixture, etc.

[0108] Although examples of preferred embodiments will be described, the present invention is not limited to these. Aerosol droplets of a carbon nanohorn aggregate mixture dispersion are sprayed onto a rotating substrate using a spin coater or the like. In the carbon nanohorn aggregate mixture dispersion, fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates exist in a monodispersed state. When this dispersion is used to form an aerosol, each droplet of the aerosol contains fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates in a monodispersed state. When these droplets are sprayed onto a substrate, the droplets containing fibrous carbon nanohorn aggregates and the droplets containing spherical carbon nanohorn aggregates fall apart. Because the substrate is rotating during this process, fibrous carbon nanohorn aggregates with high adhesive strength remain on the substrate, while spherical carbon nanohorn aggregates with a small adhesive area are more likely to be shaken off by centrifugal force. This increases the proportion of fibrous carbon nanohorn aggregates.

[0109] In one embodiment, the separation efficiency of the fibrous carbon nanohorn aggregates can be further increased by combining the method (D) with the method (A) and / or the method (B) and / or the method (C).

[0110] <Additional process> The separation method of the present disclosure may include additional steps, examples of which are described below.

[0111] Cleaning process The separation method of the present disclosure can include a step of washing, with a solvent, a substrate to which fibrous carbon nanohorn aggregates alone or a carbon nanohorn aggregate mixture with an increased ratio of fibrous carbon nanohorn aggregates is adhered. This step may also serve as the "rinsing with a solvent" step in the above (Method A). The washing step removes the spherical carbon nanohorn aggregates on the substrate, and the proportion of fibrous carbon nanohorn aggregates can be further increased. Furthermore, when a dispersion medium containing a surfactant is used as the dispersion medium for the carbon nanohorn aggregate mixture dispersion liquid, the carbon nanohorn aggregate mixture on the substrate is covered with the surfactant. By removing this surfactant by washing, the conductivity of the fibrous carbon nanohorn aggregates can be more effectively utilized. Examples of the solvent used in the washing step include water, ethanol, and 2-propanol.

[0112] Heat treatment / drying process The separation method of the present invention can include a step of heat treating and / or drying a substrate to which a single fibrous carbon nanohorn aggregate or a carbon nanohorn aggregate mixture with an increased ratio of fibrous carbon nanohorn aggregates is adhered. The heat treatment / drying step can remove the dispersion medium from the carbon nanohorn aggregate mixture dispersion liquid. Furthermore, the heat treatment step can remove the surfactant used as the dispersion medium for the carbon nanohorn aggregate mixture dispersion. The heat treatment temperature can be appropriately set to a temperature equal to or higher than the decomposition temperature of the surfactant, and is preferably 150 to 500°C, more preferably 160 to 500°C, and more preferably, for example, 180 to 400°C. Furthermore, the crystallinity of carbon nanohorn aggregates can be improved by heat treating them in a non-oxidizing atmosphere such as an inert gas, hydrogen, or vacuum, etc. In this case, the heat treatment temperature can be 800°C to 2000°C, preferably 1000°C to 1500°C. If necessary, the functional groups introduced into the defects in the above-mentioned method C can be removed by heat treatment. In this case, the heat treatment temperature can be 150°C to 2000°C. To remove carboxyl groups, hydroxyl groups, etc., a temperature of 150°C to 600°C is preferred. To remove carbonyl groups, etc., a temperature of 600°C or higher is preferred.

[0113] The above steps can also produce a film of fibrous carbon nanohorn aggregates or a carbon nanohorn aggregate mixture in which the ratio of fibrous carbon nanohorn aggregates is increased. Therefore, the adhesion separation method of the present invention can also be used as a film formation method for a fibrous carbon nanohorn aggregate film or a carbon mixture film containing fibrous carbon nanohorn aggregates at a desired ratio. The thickness, density, ratio of fibrous carbon nanohorn aggregates, etc. of the formed film can be appropriately adjusted by adjusting the amount of dispersion provided on the substrate, the content and ratio of fibrous carbon nanohorn aggregates, etc.

[0114] Recovery process As described above, it is preferable to adhere and separate the fibrous carbon nanohorn aggregates on a substrate and use the fibrous carbon nanohorn aggregates while they remain attached to the substrate, but in one embodiment, the fibrous carbon nanohorn aggregates adhered and separated on the substrate may be separated and recovered from the substrate. Examples of the recovery method include immersing the substrate to which the adhered and separated fibrous carbon nanohorn aggregates are attached (which may include spherical carbon nanohorn aggregates remaining on the substrate) in an organic solvent such as ethanol, or immersing the substrate in a solvent and applying conditions such as ultrasound that make it easy for the carbon nanohorn aggregates to disperse in the solvent.

[0115] According to the adhesion separation method of the present disclosure, it is possible to increase the ratio of fibrous carbon nanohorn aggregates in a carbon nanohorn aggregate mixture. The ratio (CNB / CNHs ratio) (number ratio) of fibrous carbon nanohorn aggregates to spherical carbon nanohorn aggregates in the obtained carbon nanohorn aggregate mixture is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more. There is no upper limit, and it is also possible to isolate only the fibrous carbon nanohorn aggregates. In one embodiment, the upper limit of the CNB / CNHs ratio (number ratio) in the carbon nanohorn aggregate mixture obtained by the adhesion separation method of the present disclosure is not limited, but may be, for example, 10 or less, 5 or less, or 1 or less. [Example]

[0116] The present invention will be illustrated in more detail below with reference to examples, but the present invention is not limited to these examples.

[0117] (Preparation Example 1) <Preparation of carbon mixture> A carbon composite was prepared by CO2 laser ablation of a carbon target containing iron in a nitrogen atmosphere chamber. Specifically, a graphite target containing 1 wt% iron was rotated at 1.5 rpm and continuously irradiated with a CO2 laser. The energy density of the CO2 laser was 50 kW / cm. 2 The temperature inside the chamber was set to room temperature, and the flow rate of nitrogen supplied into the chamber was adjusted to 10 L / min. The pressure inside the chamber was controlled to 933.254 to 1266.559 hPa (700 to 950 Torr).

[0118] The resulting carbon mixture was subjected to thermogravimetric analysis. The fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates burned at approximately 560°C, while the graphite burned at approximately 640°C. The thermogravimetric analysis revealed that the amount of graphite in the carbon mixture was approximately 20% by weight.

[0119] <Graphite removal> The carbon mixture was ultrasonically dispersed in ethanol at a concentration of 0.1 mg / ml, the dispersion was left to stand for one day, and approximately 50% of the supernatant was recovered. The supernatant was dried in an oven at 150°C to obtain a solvent-free carbon mixture from which graphite had been removed. When this carbon mixture was observed under SEM, no graphite was observed, but a large number of spherical carbon nanohorn aggregates and a small number of fibrous carbon nanohorn aggregates were observed. The fibrous carbon nanohorn aggregates had diameters of approximately 30 to 100 nm and lengths of several μm to several tens of μm. The spherical carbon nanohorn aggregates were mostly uniform in size, with diameters ranging from approximately 30 to 200 nm. The carbon mixture obtained in this manner was used as the carbon nanohorn aggregate mixture in this example.

[0120] The supernatant was diluted to a concentration of 0.01 mg / ml and used to measure particle size distribution using dynamic light scattering. As a result, size distributions in the 100 nm to 600 nm range and the 8 μm to 10 μm range were detected. Since only spherical carbon nanohorn aggregates and fibrous carbon nanohorn aggregates were observed in this sample from the SEM photograph, it was determined that the 100 nm to 600 nm range was spherical carbon nanohorn aggregates and the 8 μm to 10 μm range was fibrous carbon nanohorn aggregates.

[0121] From this size distribution region, it was found that the spherical carbon nanohorn aggregates and fibrous carbon nanohorn aggregates were in a state of being almost monodispersed or dispersed as a few aggregates in ethanol.

[0122] Furthermore, from the results of this particle size distribution measurement, it was found that the carbon nanohorn aggregate mixture after graphite removal contained 94 volume % spherical carbon nanohorn aggregates and 6 volume % fibrous carbon nanohorn aggregates. When this result was converted into a number ratio using (length of fibrous carbon nanohorn / diameter of spherical carbon nanohorn aggregate), the ratio of fibrous carbon nanohorn aggregates to spherical carbon nanohorn aggregates (CNB / CNHs ratio) was 0.003.

[0123] (Comparative Example 1) The supernatant of the ethanol dispersion of the carbon nanohorn aggregate mixture from which graphite was removed in Preparation Example 1 was used as a carbon nanohorn aggregate mixture dispersion, and 10 μl of the dispersion was dropped onto a Si substrate with a thermal oxide film and dried. An SEM image is shown in Figure 1. It was found that a large number of spherical carbon nanohorn aggregates adhered to the fibrous carbon nanohorn aggregates, resulting in an aggregated state. The number of fibrous carbon nanohorn aggregates and the number of spherical carbon nanohorn aggregates were counted in the SEM image, and the CNB / CNHs ratio was calculated to be 0.001 (the average value of the CNB / CNHs ratio in a 10 μm × 10 μm field of view at 10 random points). This value was close to the value calculated from the particle size distribution measurement results using dynamic light scattering.

[0124] (Reference example A1 (method A)) The carbon nanohorn aggregate mixture prepared in Preparation Example 1 was dispersed in ethanol at a concentration of 0.1 mg / ml to prepare a carbon nanohorn aggregate mixture dispersion liquid.

[0125] A Si substrate with a thermally oxidized film was washed with acetone and IPA (isopropyl alcohol), treated with an oxygen plasma asher, and then 100 μl of a carbon nanohorn aggregate mixture dispersion was dropped onto it. After leaving it for 10 seconds, a spin coater was used to apply centrifugal force at 500 rpm for 10 seconds, spreading the dispersion and moving it, while simultaneously drying the substrate. The resulting Si substrate was observed under SEM, and the numbers of fibrous carbon nanohorn aggregates and spherical carbon nanohorn aggregates were counted in the SEM images to calculate the CNB / CNHs ratio, which was 0.005 (the average value of the CNB / CNHs ratio in a 10 μm × 10 μm field of view at 10 random points).

[0126] (Example 1 (Method B + Method A)) The carbon nanohorn aggregate mixture prepared in Preparation Example 1 was dispersed in ethanol at a concentration of 0.1 mg / ml to prepare a carbon nanohorn aggregate mixture dispersion liquid.

[0127] A Si substrate with a thermal oxide film was washed with acetone and IPA, treated with an oxygen plasma asher, and then immersed in an APTES aqueous solution (0.1% by volume). After rinsing with water, the substrate was dried with nitrogen blowing to form a 0.3 nm thick APTES intermediate layer.

[0128] 100 μl of the carbon nanohorn aggregate mixture dispersion was dropped onto the formed APTES intermediate layer and allowed to stand for 10 seconds. After that, centrifugal force was applied using a spin coater at 1000 rpm for 10 seconds to spread the dispersion, transferring it and simultaneously drying the substrate. An SEM image of the resulting Si substrate is shown in Figure 4A. The number of fibrous carbon nanohorn aggregates and the number of spherical carbon nanohorn aggregates were counted in the SEM image, and the CNB / CNHs ratio was calculated to be 0.05 (the average value of the CNB / CNHs ratio in a 10 μm × 10 μm field of view at 10 random points).

[0129] Example 2 (Method B + Method A) The same carbon nanohorn mixture dispersion liquid as in Example 1 and a Si substrate on which an APTES intermediate layer was formed were used. 100 μL of the carbon nanohorn aggregate mixture dispersion was dropped onto the formed APTES intermediate layer, left to stand for 1 minute, and then washed with water to move the dispersion (movement speed: approximately 0.5 m / s), followed by nitrogen blow drying. An SEM image of the resulting Si substrate is shown in Figure 4B. The CNB / CNHs ratio, calculated in the same manner as in Example 1, was 0.03. Under both conditions in Examples 1 and 2, CNB and CNHs were separated and attached to the substrate in a monodispersed state, and the CNB / CNHs ratio was increased compared to the dispersion before the separation step.

[0130] Example 3 (Method B + Method A) The same carbon nanohorn aggregate mixture dispersion liquid as in Example 1 and a Si substrate on which an APTES intermediate layer was formed were used. The Si substrate with the APTES intermediate layer formed thereon was immersed in the carbon nanohorn aggregate mixture dispersion and then pulled up, shaking off the droplets of the dispersion liquid on the substrate (acceleration: approximately 50 m / s 2 The substrate was dried by nitrogen blowing. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.05.

[0131] Example 4 (Method B + Method A) The same carbon nanohorn aggregate mixture dispersion liquid as in Example 1 and a Si substrate on which an APTES intermediate layer was formed were used. The Si substrate with the APTES intermediate layer formed thereon was immersed horizontally in the carbon nanohorn aggregate mixture dispersion liquid, and the substrate was rotated horizontally (rotation speed: 50 rpm, substrate size: 10 mm × 10 mm) and then pulled up, followed by air drying. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.01.

[0132] Example 5 (Method B + Method A) The same carbon nanohorn aggregate mixture dispersion liquid as in Example 1 and a Si substrate on which an APTES intermediate layer was formed were used. The Si substrate with the APTES intermediate layer formed thereon was immersed vertically in the carbon nanohorn aggregate mixture dispersion liquid, and the substrate was moved up and down (speed: 0.3 m / s), then pulled up and dried by nitrogen blowing. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.02.

[0133] Example 6 (Method B + Method A) The same carbon nanohorn aggregate mixture dispersion liquid as in Example 1 and a Si substrate on which an APTES intermediate layer was formed were used. The Si substrate with the APTES intermediate layer formed thereon was immersed horizontally in the carbon nanohorn aggregate mixture dispersion, and ultrasonic waves (conditions: 45 kHz, 1 minute) were applied to the dispersion, and then the substrate was pulled up and dried by nitrogen blowing. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.02.

[0134] (Comparative Example 2) The carbon nanohorn aggregate mixture prepared in Preparation Example 1 was dispersed in IPA at a concentration of 0.1 mg / ml to prepare a carbon nanohorn aggregate mixture dispersion liquid. A silver substrate was washed with acetone and IPA and treated with an oxygen plasma asher to prepare a silver substrate without an intermediate layer. 10 μl of the prepared dispersion was dropped onto the silver substrate and allowed to dry. SEM observation revealed that, as in Figure 1, a large number of spherical carbon nanohorn aggregates adhered to the fibrous carbon nanohorn aggregates, forming an aggregated state. The CNB / CNHs ratio, calculated in the same manner as in Comparative Example 1, was 0.001.

[0135] Example 7 (Method B + Method A) The silver substrate was washed with acetone and IPA, treated with an oxygen plasma asher, then immersed in an IPA solution (0.2 wt%) of the thiol compound 10-Carboxy-1-decanethiol, removed, and air-dried to form an intermediate layer approximately 5 nm thick. 100 μl of the same carbon nanohorn aggregate mixture dispersion liquid as in Comparative Example 2 was dropped onto the formed intermediate layer, and after leaving it to stand for 10 minutes, the droplets of the dispersion liquid on the substrate were shaken off (acceleration: about 50 m / s 2 The substrate was dried by nitrogen blowing. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.03.

[0136] Example 8 (Method C + Method A) The carbon nanohorn aggregate mixture prepared in Preparation Example 1 was placed in 30 wt % hydrogen peroxide water and heated at 70°C for 30 minutes while stirring to create defects in the carbon nanohorn aggregates. The carbon nanohorn aggregate mixture was then filtered through a filter and washed 10 times with pure water. This carbon nanohorn aggregate mixture with defects created was dispersed in ethanol at a concentration of 0.1 mg / ml to prepare a defective carbon nanohorn aggregate mixture dispersion.

[0137] A Si substrate with a thermally oxidized film was washed with acetone and IPA and treated with an oxygen plasma asher. While the Si substrate was being rotated with a spin coater (condition: 500 rpm), 100 μl of the prepared defective carbon nanohorn aggregate mixture dispersion was dropped onto the substrate, and the dispersion was spread to move the dispersion, while the substrate was simultaneously dried. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.03.

[0138] Example 9 (Method C + Method A + Method B) The same defective carbon nanohorn aggregate mixture dispersion liquid was used as in Example 8. A Si substrate with a thermally oxidized film was washed with acetone and IPA, treated with an oxygen plasma asher, and then immersed in an APTES aqueous solution (0.1% by volume), washed with water, and then dried with nitrogen blow to form a 0.3 nm thick APTES intermediate layer.

[0139] While rotating the Si substrate with a spin coater (condition: 1500 rpm), 100 μl of the defective carbon nanohorn aggregate mixture dispersion was dropped onto the formed APTES intermediate layer, and the dispersion was spread to move the dispersion, and at the same time the substrate was dried. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.05.

[0140] Furthermore, in the SEM images of Examples 1 to 9, the number of fibrous carbon nanohorn aggregates in a monodispersed state (not adhering to spherical carbon nanohorn aggregates) and the number of fibrous carbon nanohorn aggregates to which spherical carbon nanohorn aggregates were attached were counted, and the ratio of fibrous carbon nanohorn aggregates in a monodispersed state was calculated to be 0.002 to 0.001. The ratio was calculated by the number of fibrous carbon nanohorn aggregates in a monodispersed state / (number of fibrous carbon nanohorn aggregates in a monodispersed state + number of fibrous carbon nanohorn aggregates to which spherical carbon nanohorn aggregates are attached) (the same applies hereinafter).

[0141] Example 10 (Method D + Method A) A carbon nanohorn aggregate mixture dispersion liquid was prepared by dispersing the carbon nanohorn aggregate mixture prepared in Preparation Example 1 in ethanol at a concentration of 0.1 mg / ml. A Si substrate with a thermal oxide film was washed with acetone and IPA and treated with an oxygen plasma asher.

[0142] While rotating the Si substrate with a spin coater (condition: 1000 rpm), the prepared carbon nanohorn aggregate mixture dispersion was sprayed onto the substrate with a spray, and the substrate was simultaneously dried. The D50 droplet diameter of the aerosol observed with a laser diffraction particle size distribution analyzer was 50 μm.

[0143] The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.08. Furthermore, in the SEM image, the number of monodispersed fibrous carbon nanohorn aggregates and the number of fibrous carbon nanohorn aggregates to which spherical carbon nanohorn aggregates were attached were counted, and the ratio of monodispersed fibrous carbon nanohorn aggregates was calculated to be 0.03 (average value of results in a 10 μm × 10 μm field of view at 10 random points).

[0144] Example 11 (Method D + Method A + Method B) The carbon nanohorn aggregate mixture prepared in Preparation Example 1 was dispersed in ethanol at a concentration of 0.1 mg / ml to prepare a carbon nanohorn aggregate mixture dispersion liquid. The Si substrate with the thermal oxide film was washed with acetone and IPA, treated with an oxygen plasma asher, and then immersed in an APTES aqueous solution (0.1% by volume). After rinsing with water, it was dried with nitrogen blowing to form a 0.3 nm thick APTES intermediate layer. While rotating the Si substrate with the APTES intermediate layer by a spin coater (condition: 2000 rpm), the prepared carbon nanohorn aggregate mixture dispersion was sprayed onto the substrate by a sprayer, and the substrate was simultaneously dried. The D50 droplet diameter of the aerosol observed by a laser diffraction particle size distribution analyzer was 50 μm.

[0145] The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.2. In addition, the number of monodispersed fibrous carbon nanohorn aggregates and the number of fibrous carbon nanohorn aggregates to which spherical carbon nanohorn aggregates were attached were counted in the SEM image, and the ratio of monodispersed fibrous carbon nanohorn aggregates was calculated to be 0.1 (average value of results in a 10 μm × 10 μm field of view at 10 random points).

[0146] Example 12 (Method D + Method A + Method B) The same carbon nanohorn aggregate mixture dispersion liquid as in Example 11 and a Si substrate on which an APTES intermediate layer was formed were used. While the Si substrate on which the APTES intermediate layer was formed was being rotated by a spin coater (conditions: 2000 rpm), the prepared carbon nanohorn aggregate mixture dispersion was aerosol-sprayed onto the substrate using a sprayer capable of producing a finer mist than that used in Example 11, and the substrate was simultaneously dried. The D50 droplet diameter of the aerosol observed with a laser diffraction particle size distribution analyzer was 5 μm.

[0147] An SEM image of the obtained Si substrate is shown in Figure 5. The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.5. In addition, in the SEM image, the number of monodispersed fibrous carbon nanohorn aggregates and the number of fibrous carbon nanohorn aggregates to which spherical carbon nanohorn aggregates were attached were counted, and the ratio of monodispersed fibrous carbon nanohorn aggregates was calculated to be 0.5 (the average value of the results in a 10 µm × 10 µm field of view at 10 random points).

[0148] Example 13 (Method D + Method A + Method B) The same carbon nanohorn aggregate mixture dispersion liquid as in Example 11 and a Si substrate on which an APTES intermediate layer was formed were used. The Si substrate with the APTES intermediate layer formed was placed vertically to the horizontal plane, and the prepared carbon nanohorn aggregate mixture dispersion was sprayed onto the substrate at an angle of approximately 45° using a sprayer. The aerosol droplet diameter D50 of the aerosol measured with a laser diffraction particle size distribution analyzer was 50 μm.

[0149] The CNB / CNHs ratio calculated in the same manner as in Example 1 was 0.05. In addition, the number of monodispersed fibrous carbon nanohorn aggregates and the number of fibrous carbon nanohorn aggregates to which spherical carbon nanohorn aggregates were attached were counted in the SEM image, and the ratio of monodispersed fibrous carbon nanohorn aggregates was calculated to be 0.1 (average value of results in a 10 μm × 10 μm field of view at 10 random points).

[0150] In the Si substrates obtained in Examples 10 to 13, the fibrous carbon nanohorn aggregates adhered at a distance from the spherical carbon nanohorn aggregates without agglomerating compared to Examples 1 and 2 (FIGS. 4A and 4B), and the CNB / CNHs ratio was also significantly higher than in Examples 1 and 2. These results demonstrated that more effective CNB separation and adhesion is possible by including the aerosol spraying step and the substrate or dispersion transfer step.

[0151] [Note] Some or all of the above embodiments can be described as follows, but the disclosure of the present application is not limited to the following supplementary notes.

[0152] (Appendix 1) A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates on a substrate having an intermediate layer on its surface having functional groups that enhance adhesion to the fibrous carbon nanohorn aggregates; a step of moving at least one of the dispersion liquid on the intermediate layer and the substrate; A method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

[0153] (Appendix 2) A step of creating defects in the fibrous carbon nanohorn aggregates, modifying them with functional groups that increase adhesion to a substrate, and / or binding them with a compound that increases adhesion to a substrate; A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates in which defects have been created by the above step, or which have been modified with a functional group that increases adhesion to the substrate, and / or to which a compound that increases adhesion to the substrate has been bonded, on a substrate; moving at least one of the dispersion on the substrate and the substrate; A method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

[0154] (Appendix 3) 3. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to claim 2, wherein the substrate has an intermediate layer on its surface having functional groups that enhance adhesion to the fibrous carbon nanohorn aggregates.

[0155] (Appendix 4) A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates on a substrate by spraying the dispersion liquid in an aerosol state. A method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

[0156] (Appendix 5) 5. The adhesion and separation method for fibrous carbon nanohorn aggregates according to claim 4, comprising a step of moving at least one of the aerosol droplets on the substrate and the substrate.

[0157] (Appendix 6) 6. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to claim 4 or 5, wherein the substrate has an intermediate layer on its surface having functional groups that enhance adhesion to the fibrous carbon nanohorn aggregates.

[0158] (Appendix 7) 7. The method for adhesion separation of fibrous carbon nanohorn aggregates according to any one of appendices 4 to 6, wherein the dispersion containing the carbon nanohorn aggregate mixture contains fibrous carbon nanohorn aggregates that have defects created therein, have been modified with functional groups that enhance adhesion to the substrate, and / or have been bound with compounds that enhance adhesion to the substrate.

[0159] (Appendix 8) 8. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of appendices 1 to 7, wherein 0.1% (number ratio) or more of the fibrous carbon nanohorn aggregates adhere to the substrate in a monodispersed state.

[0160] (Appendix 9) 9. The adhesion and separation method for fibrous carbon nanohorn aggregates according to any one of appendixes 1 to 8, wherein the dispersion medium of the dispersion liquid is an organic solvent, an aqueous solvent, or a mixed solvent of an organic solvent and an aqueous solvent.

[0161] (Appendix 10) The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of appendixes 2, 3 and 7 to 9, wherein the compound that enhances adhesion to the substrate is cyclodextrin.

[0162] (Appendix 11) The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of Appendices 2, 3, and 7 to 10, wherein the functional group that enhances adhesion to the substrate is selected from the group consisting of a carbonyl group, a carboxyl group, a hydroxyl group, a nitro group, a sulfone group, a phenol group, an ether bond, an ester bond, and an imino group.

[0163] (Appendix 12) 12. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of appendixes 4 to 11, wherein the substrate is moved simultaneously with the spraying of the aerosol.

[0164] (Appendix 13) 12. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of claims 5 to 11, wherein the substrate is moved after the aerosol droplets have come into contact with the substrate.

[0165] (Appendix 14) 14. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of appendixes 9 to 13, wherein the aqueous solvent contains a surfactant.

[0166] (Appendix 15) 15. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of appendixes 1 to 14, wherein the concentration of the carbon nanohorn aggregate mixture in the dispersion is in the range of 10 μg / ml to 100 mg / ml.

[0167] (Appendix 16) The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of appendices 1, 3, and 6 to 15, wherein the functional group that enhances adhesion to the fibrous carbon nanohorn aggregates is selected from the group consisting of primary amino groups, secondary amino groups, tertiary amino groups, ammonium groups, imino groups, imide groups, amide groups, epoxy groups, isocyanurate groups, isocyanate groups, ureido groups, sulfide groups, and mercapto groups.

[0168] (Appendix 17) The method for adhesion and separation of fibrous carbon nanohorn aggregates according to any one of appendixes 1, 3, and 6 to 16, wherein the intermediate layer is a layer made of 3-aminopropyltriethoxysilane (APTES) or polylysine.

Claims

1. A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates on a substrate having an intermediate layer on its surface having functional groups that enhance adhesion to the fibrous carbon nanohorn aggregates; a step of moving at least one of the dispersion liquid on the intermediate layer and the substrate; A method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

2. A step of creating defects in the fibrous carbon nanohorn aggregates, modifying them with functional groups that increase adhesion to a substrate, and / or bonding them with a compound that increases adhesion to a substrate; A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates in which defects have been created by the above step, or which have been modified with a functional group that increases adhesion to the substrate, and / or to which a compound that increases adhesion to the substrate has been bonded, on a substrate; moving at least one of the dispersion on the substrate and the substrate; A method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

3. 3. The method for adhering and separating fibrous carbon nanohorn aggregates according to claim 2, wherein the substrate has, on its surface, an intermediate layer having functional groups that enhance adhesiveness to the fibrous carbon nanohorn aggregates.

4. A step of providing a dispersion liquid containing a carbon nanohorn aggregate mixture containing fibrous carbon nanohorn aggregates on a substrate by spraying the dispersion liquid in an aerosol state. A method for adhering and separating fibrous carbon nanohorn aggregates, comprising:

5. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to claim 4 , comprising a step of moving at least one of the aerosol droplets on the substrate and the substrate.

6. 6. The method for adhering and separating fibrous carbon nanohorn aggregates according to claim 4, wherein the substrate has, on its surface, an intermediate layer having functional groups that enhance adhesiveness to the fibrous carbon nanohorn aggregates.

7. 6. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to claim 4 or 5, wherein the dispersion containing the carbon nanohorn aggregate mixture contains fibrous carbon nanohorn aggregates that have defects created therein, have been modified with functional groups that enhance adhesion to a substrate, and / or have been bound to compounds that enhance adhesion to a substrate.

8. 5. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to claim 1, wherein 0.1% (number ratio) or more of the fibrous carbon nanohorn aggregates adhere to the substrate in a monodispersed state.

9. 5. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to claim 1, wherein the dispersion medium of the dispersion liquid is an organic solvent, an aqueous solvent, or a mixed solvent of an organic solvent and an aqueous solvent.

10. The method for adhesion and separation of fibrous carbon nanohorn aggregates according to claim 2, wherein the compound that enhances adhesion to a substrate is cyclodextrin.

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