JP5109129B2 - Method for producing carbon nanotube dispersion - Google Patents

Description

  The present invention relates to a method for producing a dispersion liquid containing carbon nanotubes, and more specifically, a dispersion liquid in which carbon nanotubes are stably dispersed is produced from bundle-like carbon nanotubes (or a carbon nanotube mixture). Regarding the method. Furthermore, the present invention also relates to a member manufactured using the carbon nanotube dispersion obtained by the method of the present invention.

  A carbon nanotube (hereinafter also abbreviated as “CNT”) is one of carbon allotropes having a structure in which a graphite sheet having a hexagonal network of carbon atoms arranged in a cylindrical shape, and its diameter is on the order of nanometers. Have Two types of carbon nanotubes are known: single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). Single-walled carbon nanotubes are obtained by winding only one graphite sheet in a cylindrical shape, whereas multi-walled carbon nanotubes are obtained by overlapping graphite sheets concentrically in multiple layers at approximately equal intervals. . Such carbon nanotubes are expected to be applied in various fields because they have unique functions due to their unique structures. In particular, single-walled carbon nanotubes are considered to be suitable for applications such as gas storage materials such as hydrogen or electrode members because of their relatively large specific surface area.

  However, purified carbon nanotubes produced by conventional production methods are not always convenient for various applications. In the purification of carbon nanotubes, generally, a carbon nanotube is sonicated in an acidic solution (see, for example, Non-Patent Document 1), and then neutralized and diluted to obtain a mixture. Does not contain carbon nanotubes stably. That is, in such a mixture, the carbon nanotubes are not stably dispersed with respect to the solvent in time, and the carbon nanotubes aggregate / precipitate with the passage of time. As a result, the application range of carbon nanotubes is necessarily limited.

  In the mixture containing carbon nanotubes purified as described above, the carbon nanotubes exist in a bundle (bundle shape) of several to several hundreds due to self-association in the solvent, so the specific surface area of the carbon nanotubes Is considerably reduced compared to the theoretical value. Therefore, in the gas storage material manufactured from such a mixture containing bundle-like carbon nanotubes, the gas storage amount is smaller than the theoretical value. In addition, an electrode manufactured using such a mixture containing bundle-like carbon nanotubes has a lower electrode efficiency than the theoretical value because the contact area between the carbon nanotubes and the electrode is reduced.

  In order to obtain an alcohol dispersion of single-walled carbon nanotubes, a method using vinylpyridine as a solubilizing agent is disclosed, but it is not practical because ultrasonic treatment for 6 hours is required (for example, non-patent literature) 2). In addition, a method for producing an amide-based polar organic solvent dispersion of single-walled carbon nanotubes using polyvinylpyrrolidone as a solubilizing agent has been disclosed, but a nonionic surfactant is an essential component. One hour of sonication is required (see, for example, Patent Document 1).

  Also disclosed is a method using a polythiophene polymer to obtain a carbon nanotube dispersion. As a method for obtaining a dispersion, (1) CNT is preliminarily dispersed in a solvent under ultrasonic irradiation, and then a conjugated polymer is added and dispersed. (2) CNT and a conjugated polymer are mixed in a solvent. Then, a method of dispersing under ultrasonic irradiation, and (3) a method of adding and dispersing CNT in a molten conjugated polymer are disclosed (for example, see Patent Document 2 and paragraph 0016).

Jie Liu, Andrew G. Rinz1er, etc, “Fullerene Pipes”, Science, 1998.5.22, No. 280, p1253-1256 Jason H. Rouse, “Polymer-Assisted Disposition of Single-Walled Carbon Nanotubes in Alcohols and Applicability toward Carbon 105 JP 2005-154630 A Japanese Patent Laying-Open No. 2005-08738

  An object of the present invention is to provide a method for producing a dispersion in which carbon nanotubes are stably dispersed in a shorter time and by a simpler method. Moreover, the subject of this invention is also providing the member manufactured from the dispersion liquid containing the carbon nanotube obtained by the method of this invention.

In order to solve the above problems, the present invention provides:
A method for producing a dispersion comprising carbon nanotubes, comprising:
(I) a step of subjecting the carbon nanotube and the cyclic organic compound to vibration pulverization at a frequency of 5 to 120 s ⁻¹ to obtain a carbon nanotube mixture (hereinafter also referred to as “step (i)”), and (ii) A step of adding an organic solvent to the carbon nanotube mixture to obtain a dispersion liquid containing carbon nanotubes (hereinafter also referred to as “step (ii)”)
Comprising
Provided is a method for producing a carbon nanotube dispersion, wherein the cyclic organic compound used in step (i) is soluble in the organic solvent used in step (ii).

  As used herein, the term “vibration crushing” (or simply “vibration” or “crushing”) directly applies a mechanical impact to the carbon nanotubes to directly apply a mechanical shear force to the carbon nanotubes. That means substantially. The method of the present invention has a feature that a dispersion liquid containing carbon nanotubes can be obtained by carrying out such vibration pulverization. In addition, the step (ii) of obtaining a dispersion containing carbon nanotubes also has a feature of additionally performing centrifugation and / or filter filtration. In the step (i) of obtaining the carbon nanotube mixture, the carbon nanotube bundle can be at least partially dissociated.

In the production method of the present invention, a dispersion containing about 5.0 × 10 ⁻⁴ wt% to about 15 × 10 ⁻¹ wt% carbon nanotubes is provided. For example, the present invention provides a carbon nanotube dispersion containing carbon nanotubes, alcohol as an organic solvent, an ether organic solvent or an amide organic solvent, and polyvinylpyrrolidone as a cyclic organic compound. There is also provided a carbon nanotube dispersion containing carbon nanotubes, an amide organic solvent, a sulfoxide or halogen organic solvent as an organic solvent, and polythiophene as a cyclic organic compound.

In addition to the above invention, in the present invention,
A member including a substrate having a carbon nanotube film on the surface,
There is provided a member characterized in that the carbon nanotube film is a film formed by applying a dispersion containing carbon nanotubes obtained by the method of the present invention to the surface of a substrate and then drying it. .

  Also provided is a member made of a polymer material containing carbon nanotubes, which is obtained by mixing and molding a dispersion containing carbon nanotubes obtained by the method of the present invention into a polymer material. .

  According to the method of the present invention, a dispersion in which carbon nanotubes are stably dispersed can be obtained in a shorter time and more simply. In the obtained dispersion liquid, the carbon nanotubes are stably dispersed in an organic solvent with respect to time, and the long-term stability is excellent. Thus, such a dispersion can be considered substantially a solution.

  In addition, since the dispersion in which the carbon nanotubes are stably dispersed contains at least the carbon nanotubes in which the bundles are dissociated, the specific surface area of the carbon nanotubes is higher than that in the case where the carbon nanotubes are bundled in the solvent. To increase. Therefore, when a member manufactured using such a dispersion is used as a gas occlusion product, the gas occlusion amount increases as compared with the case of using bundle-like carbon nanotubes, and approaches the theoretical value. In addition, since the carbon nanotubes in which the bundle is dissociated have a larger contact area with the electrode surface than the bundle-like one, the member manufactured using the dispersion obtained by the method of the present invention is used as the electrode. What was there will be highly efficient, and its efficiency will be closer to the theoretical value. The “theoretical value” here refers to an ideal state of hydrogen storage or electrode efficiency based on the assumption that all of the carbon nanotubes contained in such a member are dissociated bundles.

FIG. 1 shows the appearance of a dispersion obtained by the production method of the present invention, and shows the appearance of a dispersion of polyvinylpyrrolidone (PVP) -single-walled carbon nanotubes (SWNT) under various solvent conditions. FIG. 2 shows the visible-ultraviolet absorption spectrum of the dispersion obtained by the production method of the present invention. Polyvinylpyrrolidone (PVP) -single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) under various solvent conditions. ) Shows the visible-ultraviolet absorption spectrum of the dispersion. FIG. 3 shows the Raman absorption spectrum of the dispersion obtained by the production method of the present invention. The Raman of the dispersion (organic solvent: isopropanol) containing polyvinylpyrrolidone (PVP) -single-walled carbon nanotubes (SWNT). An absorption spectrum is shown. FIG. 4 shows the appearance of the dispersion obtained by the production method of the present invention. PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) -single-walled carbon nanotube (SWNT) under various solvent conditions The appearance of the dispersion liquid is shown. FIG. 5 shows the visible-ultraviolet absorption spectrum of the dispersion obtained by the production method of the present invention. PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) -single-layer carbon under various solvent conditions The visible-ultraviolet absorption spectrum of the dispersion liquid of a nanotube (SWNT) is shown. FIG. 6 shows the near-infrared absorption spectrum of the dispersion obtained by the production method of the present invention. PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) -single-layer carbon under various solvent conditions The near-infrared absorption spectrum of the dispersion liquid of a nanotube (SWNT) is shown. FIG. 7 is a schematic diagram showing a preferred embodiment of the vibration pulverization process of the present invention. 8, the container and the hard balls may be used in the production method of the present invention (middle cutaway view) schematically illustrates a longitudinal length L _b and the short side direction length S _b of the hollow portion in the container with illustrated shows a diameter R _a of the hard ball schematically. FIG. 9 is a TEM photograph showing single-walled carbon nanotubes contained in the carbon nanotube dispersion obtained by the production method of the present invention. FIG. 9A uses CHCl ₃ and FIG. 9B uses NMP as an organic solvent.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Carbon nanotube, 2 ... Hard sphere, 3 ... Container, 4 ... Hollow part in a container.

  Below, the manufacturing method of the dispersion liquid containing the carbon nanotube of this invention is demonstrated. It should be noted that the cyclic organic compound that is subjected to vibration pulverization together with the carbon nanotubes is sometimes described simply as “dispersant” in the present specification.

In the present invention, “carbon nanotubes (specifically, carbon nanotubes that can be used in the step (i))” are, for example, arc discharge, laser evaporation, laser application, and CVD (or chemical vapor deposition). , Chemical Vapor Deposition) or the like, which means a bundle-like carbon nanotube manufactured by a conventional manufacturing method. A mixture in which such carbon nanotubes are dispersed in a medium in a bundle state has poor long-term stability, and the dispersed carbon nanotubes aggregate and precipitate over time. For example, in such a mixture, a precipitate of carbon nanotubes can be seen in 2 to 3 days at the latest.
In the present invention, the carbon nanotubes subjected to vibration pulverization may be purified or those that have been subjected to freeze-drying after purification, but are more simply commercially available carbon nanotubes. The carbon nanotubes subjected to vibration pulverization may be either single-walled carbon nanotubes or multi-walled carbon nanotubes. In either case, a dispersion can be easily obtained in a short time, and the dispersion stability of the dispersion can be improved. It will be expensive.

The cyclic organic compound as a dispersant used in the present invention is soluble in the organic solvent used in step (ii). This cyclic organic compound can disperse the obtained carbon nanotubes, and therefore contributes to obtaining a dispersion containing the carbon nanotubes stably.
The cyclic organic compound is preferably at least one synthetic polymer selected from the group consisting of polyvinyl pyrrolidone (PVP), polystyrene sulfonate, and polythiophene, for example.
It is also preferred that the cyclic organic compound is a π-based compound. Here, the “π-based compound” refers to a compound having a wide conjugated system and having a stronger π-π interaction, and is selected from the group consisting of porphyrin derivatives, pyrene derivatives, anthracene derivatives, and polythiophene derivatives, for example. It is preferable that it is at least 1 or more types of compound. When the cyclic organic compound is a π-based compound, since the carbon nanotube is a π-based compound, a π-π interaction occurs between the cyclic organic compound and the carbon nanotube. Since a force attracting each other with the cyclic organic compound is generated, an effect of assisting dissociation of the bundle of carbon nanotubes can be provided.
As a matter of course, the cyclic organic compound may be a synthetic polymer and may be a π-based compound, for example, 3- (2-methoxyethoxy) -ethoxymethylthiophene (PMET). can do.
Although the cyclic organic compounds exemplified above are preferable as the dispersant used in the present invention, the dispersant used in the present invention is a compound that is soluble in an organic solvent and stably disperses carbon nanotubes. There is no particular limitation. For example, Nafion (registered trademark, Nafion) or polyethylene glycol can be used as a dispersant.

  The mass ratio between the cyclic organic compound and the carbon nanotube will be described. For example, when the cyclic organic compound is 10 mg, the mass ratio between the cyclic organic compound provided in the container and the dried carbon nanotube is about 10: 1. To about 1: 200, preferably about 5: 1 to about 1: 100, more preferably about 1: 1 to about 1:50.

  The organic solvent used in the present invention is preferably an alcohol, an ether organic solvent, an amide organic solvent, a sulfoxide or a halogen organic solvent. The alcohol is at least one alcohol selected from the group consisting of primary alcohols such as methanol and ethanol, secondary alcohols such as isopropanol, and tertiary alcohols such as t-butanol (tert-butanol). Preferably there is. The ether organic solvent is preferably at least one ether organic solvent selected from the group consisting of diethyl ether and tetrahydrofuran. The amide organic solvent is preferably at least one amide organic solvent selected from the group consisting of 1-methyl-2-pyrrolidone and N, N-dimethylformamide. As the sulfoxide, dimethyl sulfoxide is preferable. As the halogen-based organic solvent, at least one halogen-based organic solvent selected from the group consisting of chloroform, methylene chloride and 1,1,2,2-tetrachloroethane is preferable, and among them, chloroform is particularly preferable. The carbon nanotube dispersion of the present invention may contain other components as necessary.

  If the organic solvent or the cyclic organic compound is as exemplified above, a highly dispersible carbon nanotube dispersion can be obtained. Here, when the combination of a preferable organic solvent and a cyclic organic compound is illustrated, as an organic solvent, either alcohol, 1-methyl-2-pyrrolidone or N, N-dimethylformamide, and polyvinylpyrrolidone as a cyclic organic compound, As the organic solvent, a combination of 1-methyl-2-pyrrolidone, N, N-dimethylformamide, dimethyl sulfoxide or chloroform and a cyclic organic compound with polythiophene can be given. Among them, a combination using polythiophene as a cyclic organic compound, 1-methyl-2-pyrrolidone as an organic solvent, or a combination using polyvinylpyrrolidone (PVP) as a cyclic organic compound and isopropanol as an organic solvent is preferable. Thereby, a suitable carbon nanotube dispersion can be obtained.

In the vibration pulverization processing step of the present invention (ie, the step (i) of obtaining a carbon nanotube mixture), the carbon nanotubes and the cyclic organic compound are charged together with the hard balls into the container, and then the hard balls are vibrated with respect to the container. It is preferable to perform vibration pulverization. More specifically, the carbon nanotubes, the cyclic organic compound, and the hard sphere are provided to the hollow part of the container body (hereinafter also referred to as “container hollow part”), and the hard sphere is vibrated with respect to the container. As used herein, “vibrating a hard sphere with respect to a container” substantially refers to an aspect in which the collision between the hard sphere and the wall surface of the container hollow portion is repeated over time. Therefore, “vibrating the hard ball with respect to the container” means not only a mode in which the container itself is reciprocated and the hard ball contained therein is reciprocated, but the hard ball is reciprocated from the outside with the container itself fixed. It also includes a mode of exercise.
In the case of reciprocating the container (see FIG. 7), it is generally preferable that the reciprocating direction is the longitudinal direction of the container hollow part, so that the longitudinal direction of the container hollow part is the horizontal direction. When installing the container on the vibrator, it is preferable to move the container so as to reciprocate left and right in the horizontal direction. However, if the collision between the hard sphere and the wall surface of the container hollow portion is repeatedly performed, the vibration direction of the container itself is not particularly limited, and the form of the container and / or the container hollow portion or the container installed on the vibrator The direction to vibrate may be changed as appropriate according to the method of the above, for example, the direction of reciprocation may change over time.

  As an example of a mode in which the hard sphere reciprocates in a state where the container itself is fixed, a hard sphere made of a magnetic material or a container made of a non-magnetic material is used. A mode in which reciprocating motion is performed can be considered.

  In addition, “vibration” generally means a phenomenon of reciprocating around a certain point. However, “vibration” used in this specification is not necessarily limited to an aspect in which a container reciprocates only in a certain direction. If the collision between the hard sphere and the wall of the hollow portion of the container is repeated over time (that is, mechanical impact is applied directly to the carbon nanotubes and mechanical shearing force is applied to the carbon nanotubes). The container may be in a rotational and / or oscillating manner if it works. When the container rotates, not only the container rotates, but also, for example, the gantry itself on which the container is installed rotates, and the rotation direction of the container changes with time (for example, “reverse”), and the rotation direction of the gantry also changes. It is preferable that it changes with time independently of the container.

  The container generally has a container body and a lid, and is preferably a container that seals the carbon nanotube, the cyclic organic compound, and the hard sphere provided in the hollow part of the container by shielding them from the outside atmosphere. preferable. The container is preferably formed mainly from a hard material such as stainless steel, but an impact caused by vibration, for example, a hard ball reciprocating in the hollow part of the container collides with the hollow part wall surface (that is, the hollow part wall part). Any material can be used as long as it can withstand the impact caused by the above. In general, the container is preferably one that maintains a sealed state while being subjected to vibration. Accordingly, a gasket may be sandwiched between the contact surface between the container body and the lid so as to provide an appropriate seal, and the container body and the lid may be tightened with a clip or a holder from the outside.

  The container hollow portion has, for example, a cylindrical shape, and while being subjected to vibration crushing, a shape in which a hard ball can reciprocate in the longitudinal direction of the hollow portion from one end portion of the cylindrical hollow portion to the other end portion, and It is preferable to have a size. However, the container hollow portion may have any shape and size as long as the hard sphere moves and reciprocates substantially in the container hollow portion. For example, the end in the longitudinal direction of the container hollow portion (that is, the top and bottom of the cylindrical container hollow portion) is not necessarily formed in a planar shape, and may be formed in a hemispherical shape. . Incidentally, in the following description, the description will be made on the assumption that the shape of the container hollow portion is a cylindrical shape having a hemispherical top and bottom.

The hard sphere reciprocates in the hollow portion of the container, and as a result, the carbon nanotube is crushed between the hard sphere that reciprocates and preferably the frequency at which the carbon nanotube and the cyclic organic compound are mixed and / or the wall of the hollow portion. The container is preferably reciprocated at such a frequency. When the frequency is 5 s ⁻¹ or less, the vibration time may be very long. On the other hand, when the frequency is 120 s ⁻¹ or more, the carbon nanotubes cause a chemical reaction, and the degree of dispersion of the carbon nanotubes is increased. There is a possibility of lowering. Therefore, the frequency is 5 to 120 s ⁻¹ , preferably 10 to 60 s ⁻¹ , more preferably 20 to 50 s ⁻¹ . In addition, when the hard ball is vibrated with respect to the container by subjecting the container to a rotational motion, the rotational speed of the container is preferably 5 to 120 times / s, as in the case of reciprocating the container. More preferably, it can be 10 to 60 times / s, more preferably 20 to 50 times / s.

The vibration time is preferably about 1 minute to 5 hours, more preferably about 1.5 minutes to 3 hours, and still more preferably about 2 minutes to 2 hours. This is because if the vibration time is too short, the degree of dispersion of the carbon nanotubes decreases, and if the vibration time is too long, the carbon nanotubes react with each other and the degree of dispersion of the carbon nanotubes decreases. However, it should be noted that the vibration time may vary depending on vibration conditions such as frequency or amplitude. In addition to the preferred frequency and vibration time as described above, it is preferable to consider the preferred amplitude. Specifically, the hard sphere reciprocates in the hollow portion of the container, and as a result, the carbon nanotubes are crushed between the hard sphere and the reciprocating hard sphere and the hollow portion wall surface so that the carbon nanotube and the cyclic organic compound are mixed. It is preferable to vibrate the hard sphere with respect to the container with such an amplitude. When the hard sphere is vibrated with respect to the container by reciprocating the container in a certain direction, the ratio (W ₎ between the amplitude W _b when reciprocating the container and the container hollow portion length L _b in the direction of reciprocating the container _{b: L b)} is preferably 1: 1 to 50: 1, more preferably from 1: 1.2 to 20: 1, more preferably 1: 1.3 to 15: 1. Here, “amplitude” refers to the length from the center point to the maximum displacement point when the container to be reciprocated is maximally displaced with reference to the center point of the reciprocation. Further, when the container hollow part is cylindrical, it is preferable to reciprocate the container in the longitudinal direction of the container hollow part. In that case, the “container hollow part length L _b in the direction of reciprocating the container” The length in the longitudinal direction of the container hollow portion is substantially meant (see FIG. 8).
For example, in the case of using a container having a cross-sectional diameter of 20 mm and a longitudinal length of 65 mm (a cross-sectional diameter of 12 mm of the body portion of the hollow portion and a longitudinal length of the hollow portion of 50 mm), if the amplitude is too small, While carbon nanotubes and cyclic organic compounds cannot be mixed efficiently in the hollow part of the container, if the amplitude is too large, hard balls collide with the wall of the hollow part of the container (for example, the wall at the top or bottom of the cylindrical hollow part of the container) Since the container itself will continue to move after the operation, the loss is great both in terms of time and energy, so that it is hollow with an amplitude of 5 to 100 mm, preferably an amplitude of 10 to 80 mm, more preferably an amplitude of 20 to 50 mm. The container is reciprocated in the longitudinal direction.

  The hard spheres provided in the container in the vibration pulverization process preferably have a spherical shape, but any shape suitable for the hard sphere to reciprocate in the hollow portion while the hard sphere vibrates with respect to the container. It does not matter even if it is a shape. For example, in the case of a container hollow portion size having a cross-sectional diameter of 12 mm and a longitudinal length of 50 mm, the hard sphere is a sphere having a diameter of 2 to 10 mm, preferably a diameter of 4 to 6 mm, more preferably a diameter of 5 mm. Further, while the hard sphere vibrates with respect to the container, the hard sphere reciprocates in the hollow portion of the container, and as a result, preferably has such hardness that the carbon nanotubes are crushed between the hard ball and the wall surface of the hollow portion of the container. It is preferable that the hard sphere and the wall surface of the container hollow part have. For example, if the hardness of the hard sphere and the hardness of the wall surface of the hollow portion of the container are Mohs hardness 4 or less, the deformation of the hard sphere and a decrease in the mixing efficiency (decrease in the mixing efficiency of the carbon nanotube and the cyclic organic compound) may occur. There is sex. Accordingly, the hardness of the hard sphere is preferably a Mohs strength of 4 to 9.5, more preferably a Mohs strength of 5 to 9.5, and still more preferably a Mohs hardness of 6 to 9.5.

  Examples of the material of the hard sphere include at least one material selected from the group consisting of agate, slenless, alumina, zirconia, tungsten carbide, chromium steel, and Teflon (registered trademark). Similarly, examples of the material of the wall surface of the hollow portion of the container include at least one material selected from the group consisting of agate, slenless, alumina, zirconia, tungsten carbide, chromium steel, and Teflon (registered trademark). Can do. The number of hard spheres provided to the container is 1 to 6, preferably 1 to 4, more preferably 2. However, the hard spheres reciprocate in the hollow portion of the container while the hard sphere vibrates with respect to the container. As a result, preferably, the number suitable for mixing the carbon nanotubes and the cyclic organic compound and / or the number suitable for pulverizing the carbon nanotubes between the reciprocating hard sphere and the wall surface of the hollow portion of the container. Any number may be used. When two or more hard balls are provided in the container, the carbon nanotubes are crushed even between the reciprocating hard balls.

The relationship between the hard sphere and the container hollow portion will be specifically described as follows. First, when considering the point that needs to hard ball reciprocates container hollow portion, the diameter R _a of the hard ball with respect to the longitudinal length L _b of the container the hollow portion is too small, it is disadvantageous in the following point . That is, if the container is small (i.e., if the longitudinal length L _b of the container the hollow portion is small), the hard ball becomes small, mixing well for the collision energy becomes small (the carbon nanotubes and the cyclic organic compound mixing) can not possibility may, if container conversely is large (i.e., when the longitudinal length L _b of the container the hollow portion is large) to the necessarily large burden and energy consumption to the amplitude is large becomes vibrator It is inconvenient in that it can be. On the other hand, if the diameter R _{a of the} hard sphere is too large with respect to the longitudinal length L _{b of} the container hollow portion, the stroke is shortened, so that the energy when the hard ball collides with the wall surface of the container hollow portion becomes small and mixing is impossible. It may be sufficient. Accordingly, the ratio (R _a : L _b ) between the diameter R _{a of} the hard sphere and the length L _b in the longitudinal direction of the hollow portion of the container is preferably 1: 1.5 to 1: 100, more preferably 1: 2. 0 to 1:75, more preferably 1: 2.5 to 1:50 (see FIG. 8). Further, the ratio (R _a : S _b ) between the diameter R _{a of} the hard sphere and the length S _b in the short direction of the container hollow part (= the cross-sectional diameter S _b of the body part of the cylindrical container hollow part) is preferably Is from 1: 1.1 to 1:30, more preferably from 1: 1.2 to 1:20, still more preferably from 1: 1.3 to 1:15 (also see FIG. 8). Here, “diameter R _a ” refers to the case where the shape of the hard sphere is spherical. However, the shape of the hard sphere is not particularly limited, and may be a shape other than a sphere. In that case, it is preferable that the hard sphere has an equivalent diameter corresponding to the “diameter” described above. The “equivalent diameter” means a diameter assumed when the shape of a non-spherical hard sphere is changed to a spherical shape without changing the volume.

The preferable relationship between the total volume of the hard spheres and the volume of the container hollow portion is as follows. For example, when the number of hard spheres is 1 to 6, the ratio of the total volume V _b of the hard spheres to the container hollow portion volume V _a (= V _b / V _a × 100 (%)) is preferably 0.2 to 40%. More preferably, it is 0.3-20%, More preferably, it is 0.5-10%. Thereby, the collision between the hard sphere and the wall surface of the hollow portion of the container is increased, and an effect that the carbon nanotubes are further crushed can be brought about.

Next, step (ii) for obtaining a dispersion will be described. In the step (ii) of obtaining the dispersion liquid, the carbon nanotube mixture after being subjected to the vibration grinding (more specifically, the mixture containing the carbon nanotube and the cyclic organic compound after being subjected to the vibration grinding) By adding an organic solvent, a dispersion containing carbon nanotubes stably can be obtained. The dispersion thus comprises the components of the organic solvent to be added, the carbon nanotubes and the cyclic organic compound. In this step, after adding an organic solvent, an operation for removing a precipitate (the precipitate substantially contains carbon nanotubes not dispersed in the organic solvent) from the obtained mixture is added as necessary. You may go to For example, after adding an organic solvent to the carbon nanotube mixture, a centrifugal operation is performed to remove the carbon nanotubes that have not been dispersed, and the resulting supernatant is fractionated to obtain a carbon nanotube dispersion. The step of obtaining the dispersion in this manner is particularly suitable when polyvinylpyrrolidone (PVP) is used as the cyclic organic compound.
In addition, you may attach | subject the supernatant obtained by said centrifugation to filter filtration. In this case, when an organic solvent is added to the residue obtained by filter filtration, a dispersion in which carbon nanotubes are stably dispersed can be obtained. The organic solvent added to the residue may be the same as the organic solvent added to the carbon nanotube mixture after being subjected to vibration grinding, or may be a solvent composed of the same main component as the organic solvent. If the carbon nanotube recovery rate by filter filtration is too low (for example, when the recovery rate is less than 2%), the carbon nanotubes contained in the finally obtained dispersion liquid will be reduced to achieve the desired carbon nanotube concentration. Is inefficient and uneconomical, but if the carbon nanotube recovery rate by filtration is too high (for example, if the recovery rate is greater than 95%), in addition to the carbon nanotubes from which the bundles have been dissociated, the bundles will also be dissociated. This is not preferable in that there is a possibility that more carbon nanotubes are not included. Therefore, the membrane filter used for filter filtration has an average membrane pore size of preferably 0.02 to 5.0 μm, and preferably 2 to 95%, more preferably 5% of carbon nanotubes contained in the supernatant. Those that can be recovered by 95% (recoverable from the supernatant) are preferred. For example, as such a membrane filter, a PTFE membrane filter (manufactured by Advantech, model: T020A025A [catalog number], pore size: 0.20 μm) can be mentioned.

  Or in the process of obtaining a dispersion liquid, the following operation can also be performed. First, an organic solvent is added to the carbon nanotube mixture after being subjected to vibration pulverization (more specifically, a mixture containing carbon nanotubes and cyclic organic compounds after being subjected to vibration pulverization), and the resulting mixture is centrifuged. Attach to separation. Next, a precipitate produced by centrifugation is collected, and a carbon nanotube dispersion liquid can be obtained by adding a solvent to the precipitate. In addition, after subjecting the obtained dispersion to ultrasonic treatment and further subjecting to centrifugation, and separating the resulting supernatant, a dispersion in which carbon nanotubes exist more stably can be obtained. The step of obtaining the dispersion in this manner is particularly suitable when a π-based compound is used as the cyclic organic compound. The “solvent added to the precipitate” may be an organic solvent added to the carbon nanotube mixture after being subjected to vibration pulverization, or may be a solvent composed of the same main component as the organic solvent.

  Here, “stable” means that carbon nanotubes are stably dispersed in an organic solvent over time, and the carbon nanotubes aggregate for at least 1 week, preferably at least 2 weeks, more preferably at least 3 weeks. / This means that no precipitation occurs. Thus, since the dispersion liquid contains the carbon nanotube stably, it can also be considered that the carbon nanotube is substantially dissolved in the solvent.

  Since the dispersion containing the carbon nanotubes contains at least the carbon nanotubes from which the bundles are dissociated, it is considered that the specific surface area of the carbon nanotubes increases in proportion to the degree to which the bundles are dissociated. Therefore, a member having a carbon nanotube film having a larger specific surface area can be produced from such a dispersion, and the member can be used as, for example, a gas storage product or an electrode. Such a gas storage product can be used for storing hydrogen gas fuel in, for example, cars and ships. As a specific example of the electrode, for example, a negative electrode such as a lithium secondary battery can be considered.

  The above-described member of the present invention has a base material, and a carbon nanotube film formed by applying a dispersion containing carbon nanotubes produced by the method of the present invention to the base material surface and then drying. Become. The base material may be made of any shape or material as long as it is a substrate or a support plate suitable for a gas storage product or an electrode, for example. In the dispersion liquid containing carbon nanotubes produced by the method of the present invention, the carbon nanotubes at least partially dissociated from the bundles exist almost uniformly in the organic solvent. As a result, the carbon nanotube film obtained by applying the dispersion to the surface of the substrate and drying it can contain carbon nanotubes substantially uniformly. Therefore, in such a carbon nanotube film, the specific surface area of the carbon nanotube is large, and a gas occlusion product or a highly efficient electrode with a large gas occlusion amount is provided.

  The dispersion obtained by the method of the present invention is used for forming a member such as a gas occlusion product or an electrode as described above, and the dispersion is subjected to a filtration treatment with a conventional membrane filter to obtain the dispersion. Only the carbon nanotubes contained in the liquid are taken out alone, and the taken-out carbon nanotubes are reinforced for field emission display (FED) emitters, photoelectric conversion elements, composite materials (plastic, rubber or resin, etc.) Therefore, it can also be used for applications such as materials to be mixed) or cosmetics.

  Furthermore, an organic polymer material containing carbon nanotubes can be obtained by using the carbon nanotube dispersion obtained by the method of the present invention. In this case, at least one organic polymer material selected from the group consisting of polyamide, polyethylene, polyvinyl alcohol, polyimine, polyacrylic resin, polyepoxy resin, polyurethane and natural rubber is used as the carbon nanotube dispersion of the present invention. By mixing with the organic polymer material, it is possible to obtain an organic polymer material that takes advantage of the characteristics of carbon nanotubes (that is, characteristics such as high elasticity, high strength, or high conductivity). Such organic polymer materials can be used as raw materials for urethane molded products, plastic molded products, rubber products, golf shafts, FRP molded products, chemical fibers, paper, etc. (or used in these materials). it can. In addition, a coating material can be obtained using a polymer material containing the dispersion of the present invention, which can be used as an antistatic agent. Further, the dispersion of the present invention is mixed with at least one organic polymer material selected from the group consisting of polyamide, polyethylene, polyvinyl alcohol, polyimine, polyacrylic resin, polyepoxy resin, polyurethane and natural rubber. The member obtained by molding by various methods can be used for various applications. For example, such a molded member can be used as an electrode because of its improved conductivity.

  The method for producing a dispersion containing carbon nanotubes of the present invention will be described over time. First, a carbon nanotube 1 (preferably a dry carbon nanotube) is prepared. Next, as shown in FIG. 7, the carbon nanotube 1 dried together with the cyclic organic compound and the two hard spheres 2 is provided in the container body hollow portion of the container 3, and the container body is covered with a lid. Then, the hard sphere 2 reciprocates in the hollow portion of the container, and as a result, the frequency and amplitude such that the carbon nanotube 1 and the cyclic organic compound are mixed and / or the carbon between the hard sphere 2 reciprocating and the wall of the hollow portion. The container 3 is reciprocated in the longitudinal direction of the hollow portion with such a frequency and amplitude that the nanotube 1 is crushed. Then, after the container 3 is reciprocated for an appropriate time, the carbon nanotubes taken out from the container 3 are diluted with an organic solvent to obtain a dispersion liquid stably containing the carbon nanotubes.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to this, It will be easily understood by those skilled in the art that various modifications can be made. Incidentally, it should be noted that the present invention described above includes the following aspects:

First aspect: A method for producing a dispersion comprising carbon nanotubes, comprising:
(I) subjecting the carbon nanotube and the cyclic organic compound to vibration pulverization at a frequency of 5 to 120 s ⁻¹ to obtain a carbon nanotube mixture; and (ii) adding an organic solvent to the carbon nanotube mixture, Comprising the step of obtaining a dispersion comprising
A method for producing a carbon nanotube dispersion, wherein the cyclic organic compound used in step (i) is soluble in the organic solvent used in step (ii).
Second aspect: In the first aspect, after the carbon nanotubes, the cyclic organic compound, and the hard sphere are provided in the container, the vibration pulverization is performed by vibrating the hard sphere with respect to the container. Method.
Third aspect: In the second aspect, the hard ball is vibrated with respect to the container by reciprocating the container in a certain direction,
The ratio W _b between the amplitude W _b and the container hollow portion in a direction for moving the container back and forth movement length L _b when reciprocating the _container: L _b is 1: 1.3 to 15: wherein the 1 .
Fourth aspect: In the second or third aspect, the number of hard spheres is 1 to 6, and the ratio of the total volume of the hard spheres to the volume of the container hollow part is 0.5 to 10%. how to.
Fifth aspect: The method according to any one of the first to fourth aspects, wherein the cyclic organic compound is a synthetic polymer selected from the group consisting of polyvinylpyrrolidone, polystyrene sulfonate, and polythiophene.
Sixth aspect: The method according to any one of the first to fourth aspects, wherein the cyclic organic compound is a π-based compound.
Seventh aspect: The method according to the sixth aspect, wherein the π-based compound is selected from the group consisting of a porphyrin derivative, a pyrene derivative, an anthracene derivative and a polythiophene derivative.
Eighth aspect: The method according to any one of the first to seventh aspects, wherein the organic solvent is an alcohol, an ether organic solvent, an amide organic solvent, a sulfoxide, or a halogen organic solvent.
Ninth aspect: In the eighth aspect, the alcohol is selected from the group consisting of methanol, ethanol, isopropanol, and t-butanol.
Tenth aspect: The process according to the eighth aspect, wherein the ether organic solvent is selected from the group consisting of diethyl ether and tetrahydrofuran.
Eleventh aspect: The process according to the eighth aspect, wherein the amide organic solvent is selected from the group consisting of 1-methyl-2-pyrrolidone and N, N-dimethylformamide.
Twelfth aspect: The method according to the eighth aspect, wherein the sulfoxide is dimethyl sulfoxide.
Thirteenth aspect: The method according to the eighth aspect, wherein the halogen-based organic solvent is selected from the group consisting of chloroform, methylene chloride and 1,1,2,2-tetrachloroethane.
Fourteenth aspect: The method according to any one of the first to thirteenth aspects, wherein the frequency is 20 to 50 s- ¹ .
Fifteenth aspect: The method according to any one of the first to fourteenth aspects, wherein the vibration crushing is performed for 2 minutes to 2 hours.
Sixteenth aspect: The method according to any one of the first to fifteenth aspects, wherein in the step (i) of obtaining a carbon nanotube mixture, a bundle of carbon nanotubes is at least partially dissociated.
Seventeenth aspect: In any one of the first to sixteenth aspects, in the step (ii) of obtaining a dispersion, after adding the organic solvent a to the carbon nanotube mixture, the resulting mixture is subjected to centrifugation. And how to.
Eighteenth aspect: The process according to the seventeenth aspect, further comprising the step of filtering the supernatant obtained by subjecting to centrifugation and adding a solvent comprising the same components as the organic solvent a to the resulting residue. ,
A method wherein a membrane filter used for filter filtration collects 5 to 95% of carbon nanotubes contained in a supernatant.
Nineteenth aspect: In the sixth aspect, in the step (ii) of obtaining a dispersion, the organic solvent a is added to the carbon nanotube mixture, the resulting mixture is subjected to centrifugation, and then the precipitate in the mixture is removed. A method of separating and adding an organic solvent comprising the same main component as the organic solvent a to the precipitate.
A twentieth aspect is a member including a base material having a carbon nanotube film on the surface,
A member, wherein the carbon nanotube film is a film formed by applying a carbon nanotube dispersion liquid obtained by the method of any one of the first to nineteenth aspects to a surface of a substrate.
Twenty-first aspect: A component according to the twentieth aspect, which is used as a gas storage product.
Twenty-second aspect: The member according to the twentieth aspect, which is used as an electrode.
23rd aspect: The polymeric material containing the carbon nanotube dispersion liquid obtained by the method in any one of the said 1st-22nd aspect.
Twenty-fourth aspect: A member made of an organic polymer material containing carbon nanotubes, wherein the carbon nanotube dispersion obtained by the method according to any one of the first to twenty-second aspects is mixed with another organic polymer material A member obtained by molding.
25th aspect: A carbon nanotube dispersion liquid comprising carbon nanotubes, polyvinylpyrrolidone, and the organic solvent according to the eighth aspect.
Twenty-sixth aspect: A carbon nanotube dispersion liquid comprising carbon nanotubes, 3- (2-methoxyethoxy) -ethoxymethylthiophene and the organic solvent according to the eighth aspect.

  Using the production method of the present invention, a dispersion containing carbon nanotubes stably was produced.

Example 1
(1) 1 mg of single-walled carbon nanotubes, 10 mg of polyvinyl pyrrolidone (PVP: average molecular weight 360,000) and two agate balls (sphere diameter 5 mm) as a dispersant, 20 mm bottom diameter, 65 mm longitudinal length The cylindrical closed container (cylindrical hollow part formed in the said container: the cross-sectional diameter of the trunk | drum 12mm, longitudinal direction length 50mm) was prepared.
(2) In a vibrator (Retsch, MM200), with the longitudinal direction of the hermetic container hollow portion being almost horizontal, the hermetic container is horizontally oriented with an amplitude of about 30 mm and a frequency of about 30 s ^−1. Was reciprocated.
(3) After reciprocating the sealed container for about 20 minutes, the black powder was taken out from the hollow part of the sealed container.
(4) About 1 ml of ethanol was added to about 11 mg of the obtained black powder, and the mixture was centrifuged at 8000 rpm for 10 minutes using a centrifuge (manufactured by Beckman Coulter, Microfuge 22R). After separation, the supernatant was separated to obtain a dispersion containing carbon nanotubes stably.
(5) In the obtained dispersion, no aggregation or precipitation of carbon nanotubes was observed until at least 4 weeks.

Example 2
(1) 1 mg of single-walled carbon nanotube, 5 mg of PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) and two agate balls (sphere diameter 5 mm) as a dispersant, 20 mm bottom diameter, 65 mm length A cylindrical sealed container having a length in the direction (cylindrical hollow portion formed in the container: a cross-sectional diameter of the trunk portion of 12 mm, a length in the longitudinal direction of 50 mm) was charged.
(2) In a vibrator (Retsch, MM200), with the longitudinal direction of the hermetic container hollow portion being almost horizontal, the hermetic container is horizontally oriented with an amplitude of about 30 mm and a frequency of about 30 s ^−1. Was reciprocated.
(3) After reciprocating the sealed container for about 20 minutes, the black powder was taken out from the hollow part of the sealed container.
(4) About 10 ml of 1-methyl-2-pyrrolidone was added to about 11 mg of the obtained black powder, and a centrifuge (manufactured by Beckman Coulter, Microfuge 22R) was used. After centrifugation at 14,000 rpm for 20 minutes, the resulting precipitate was collected.
(5) About 1 ml of 1-methyl-2-pyrrolidone is added to the obtained precipitate, and a tabletop ultrasonic cleaner (Branson Ultrasonic manufactured by Bransonic 5510) is used. After sonication for 5 minutes, centrifugation was carried out at 14,000 rpm for 60 minutes by a centrifuge (manufactured by Beckman Coulter, Microfuge 22R), and the resulting supernatant was obtained. The dispersion liquid containing carbon nanotubes stably was obtained.
(6) The obtained dispersion was not aggregated or precipitated with carbon nanotubes for at least 4 weeks.

Example 3
Under the conditions using PVP (polyvinylpyrrolidone) as a dispersant, the same operation as in Example 1 was carried out with various solvents (note that the experiment was also carried out under the condition where PVP was not used). The results are shown in Table 1 below. In the table, the CNT concentration (mg / 1 mL) means the mass (mg) of carbon nanotubes contained in 1 mL of the obtained dispersion. The concentration of CNTs was determined from the absorbance (A ₅₀₀ ) at a wavelength of 500 nm in the visible absorption spectrum when a 1 mm cell was used after diluting the dispersion 5 times, as shown in the following formula. Is obtained by using the extinction coefficient (ε ₅₀₀ = 2.86 × 10 ⁴ cm ² / g):
CNT concentration (mg / 1 mL) = A ₅₀₀ [−] × 5 [−] / (ε ₅₀₀ [cm ² /g]×0.1 [cm] × 10 ⁻³ [−]).

In Table 1 above, SWNT1 is a single-walled carbon nanotube manufactured by Carbon Nanotechnologies, Inc.
In Table 1 above, SWNT2 is a single-walled carbon nanotube manufactured by CarboLex, Inc. In Table 1 above, MWNT1 is a multiwall carbon nanotube made by Nanocyl SA.
In Table 1 above, PVP is polyvinylpyrrolidone (average molecular weight 360,000).
In Table 1 above, the numerical values of “Note” indicate that they are all dispersed or dissolved.

Referring to the results in Table 1, the following was found.
When the PVP was used as the dispersant, the CNT concentration could be confirmed, whereas when the PVP was not used, the CNT concentration was 0. Therefore, PVP plays an important role as a dispersant in the production method of the present invention.
-In the manufacturing method of this invention, a carbon nanotube dispersion liquid can be manufactured without depending on the kind of a single-walled carbon nanotube and a multi-walled carbon nanotube.
-Alcohols such as methanol, ethanol and isopropanol used as the organic solvent contribute to the formation of the carbon nanotube dispersion in the present invention.
The amide organic solvent such as 1-methyl-2-pyrrolidone and N, N-dimethylformamide used as the organic solvent contributes to the formation of the carbon nanotube dispersion in the present invention.
In order to obtain a carbon nanotube dispersion, only an organic solvent and PVP are used as raw materials, and other additional additives are not particularly required.
In view of the fact that the vibration pulverization process itself takes about 20 minutes, a carbon nanotube dispersion can be obtained in a relatively short time.

Example 4
The same operation as in Example 2 was carried out with various solvents under the condition using PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) as a dispersant. The results are shown in Table 2 below. In the table, the CNT concentration (mg / 1 mL) means the mass (mg) of carbon nanotubes contained in 1 mL of the obtained dispersion. The concentration of CNTs is determined from the absorbance (A ₇₀₀ ) at a wavelength of 700 nm in the visible absorption spectrum when a 1 mm cell is used after diluting the dispersion 10 times, as shown in the following formula. Is obtained by using the extinction coefficient (ε ₇₀₀ = 2.35 × 10 ⁴ cm ² / g): CNT concentration (mg / 1 mL) = A ₇₀₀ [−] × 10 [−] / (ε ₇₀₀ [cm ² /G]×0.1 [cm] × 10 ⁻³ [−]).

In Table 2 above, SWNT1 is a single-walled carbon nanotube manufactured by Carbon Nanotechnologies, Inc.
In Table 2 above, PMET indicates (3- (2-methoxyethoxy) -ethoxymethylthiophene) used as a dispersant, and 5 mg was used for all.

Referring to the results in Table 2, the following was found.
-PMET used as a dispersing agent contributes to formation of the carbon nanotube dispersion liquid in this invention.
A halogen-based organic solvent such as chloroform used as the organic solvent contributes to the formation of the carbon nanotube dispersion in the present invention.
-Sulfoxide such as dimethyl sulfoxide used as the organic solvent contributes to the formation of the carbon nanotube dispersion in the present invention.
-Referring also to the results in Table 1, the amide organic solvent such as 1-methyl-2-pyrrolidone and N, N-dimethylformamide used as the organic solvent is whether the dispersant is PVP or PMET. Regardless, it contributes to the formation of the carbon nanotube dispersion in the present invention.
As in the results of Table 1, in order to obtain a dispersion of carbon nanotubes, only an organic solvent and PMET are used as raw materials, and other additional additives are not particularly required.
Similar to the results in Table 1, considering that the vibration pulverization process itself takes about 20 minutes, a carbon nanotube dispersion can be obtained in a relatively short time.

Example 5
(1) 1 mg of single-walled carbon nanotubes, 10 mg of polyvinyl pyrrolidone (PVP: average molecular weight 360,000) and two agate balls (sphere diameter 5 mm) as a dispersant, 20 mm bottom diameter, 65 mm longitudinal length The cylindrical closed container (cylindrical hollow part formed in the said container: the cross-sectional diameter of the trunk | drum 12mm, longitudinal direction length 50mm) was prepared.
(2) In a vibrator (Retsch, MM200), with the longitudinal direction of the hermetic container hollow portion being almost horizontal, the hermetic container is horizontally oriented with an amplitude of about 30 mm and a frequency of about 30 s ^−1. Was reciprocated.
(3) After reciprocating the sealed container for about 20 minutes, the black powder was taken out from the hollow part of the sealed container.
(4) About 1 ml of ethanol was added to about 11 mg of the obtained black powder, and the mixture was centrifuged at 8000 rpm for 10 minutes using a centrifuge (manufactured by Beckman Coulter, Microfuge 22R). After separation, the supernatant was separated.
(5) The supernatant was filtered with a membrane filter (manufactured by Advantech, model: T020A025A [catalog number], average membrane pore size 0.20 μm). By this filtration, 10% of the carbon nanotubes contained in the supernatant were recovered.
(6) A dispersion liquid stably containing carbon nanotubes was obtained by adding ethanol to the residue obtained by filtration.
(7) In the obtained dispersion, no aggregation or precipitation of carbon nanotubes was observed until at least 4 weeks.

FIG. 1 shows the appearance of a dispersion of PVP (polyvinylpyrrolidone) -single-walled carbon nanotubes (SWNT) obtained by the production method of the present invention performed under various solvent conditions. The dispersion liquid shows black, and it is confirmed that the carbon nanotubes are dispersed in the organic solvent used.
FIG. 2 shows visible-ultraviolet absorption spectra of a dispersion of PVP (polyvinylpyrrolidone) -single-walled carbon nanotubes (SWNT) and multi-walled nanotubes (MENT) obtained by the production method of the present invention performed under various solvent conditions. Show. Absorption by carbon nanotubes was observed in the entire measurement region of 250 to 800 nm in this time, and it was confirmed that single-walled carbon nanotubes were dispersed.
FIG. 3 shows a Raman absorption spectrum of a dispersion (organic solvent: isopropanol) of PVP (polyvinylpyrrolidone) -single-walled carbon nanotubes (SWNT) obtained by the production method of the present invention. And 150～300Cm ^-1 vicinity radial breathing mode (RBM), G band near 1550 cm ^-1 due to lattice vibration within a six-membered ring network of carbon atoms have been observed, the single-walled carbon nanotubes are dispersed I confirmed. Since the radial breathing mode in the vicinity of 150 to 300 cm ⁻¹ corresponds to the semiconductor single-walled carbon nanotube, and the radial breathing mode in the vicinity of 230 to 300 cm ⁻¹ corresponds to the metal single-walled carbon nanotube, the semiconducting single-walled carbon nanotube It is considered that both the single-walled carbon nanotube and the metallic single-walled carbon nanotube are dispersed.
FIG. 4 shows the appearance of a dispersion of PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) -single-walled carbon nanotube (SWNT) obtained by the production method of the present invention performed under various solvent conditions. Show. As in FIG. 1, the dispersion showed a black color, and it was confirmed that the carbon nanotubes were dispersed in the organic solvent used.
FIG. 5 shows visible dispersion of PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) -single-walled carbon nanotubes (SWNT) obtained by the production method of the present invention performed under various solvent conditions. An ultraviolet absorption spectrum is shown. Absorption by carbon nanotubes was observed in the entire measurement region of 300 to 800 nm this time, and it was confirmed that single-walled carbon nanotubes were dispersed.
FIG. 6 shows a near red color of a dispersion of PMET (3- (2-methoxyethoxy) -ethoxymethylthiophene) -single-walled carbon nanotube (SWNT) obtained by the production method of the present invention performed under various solvent conditions. The external absorption spectrum is shown. Absorption by the carbon nanotubes was observed in the entire near-infrared region of the measurement region 800 to 1600 nm, and it was confirmed that the single-walled carbon nanotubes were dispersed.

[TEM photograph of single-walled carbon nanotubes in dispersion]
9A and 9B show TEM photographs of single-walled carbon nanotubes contained in the carbon nanotube dispersion obtained by the production method of the present invention. 9 (a) and 9 (b) are TEM photographs when different organic solvents are used. In FIG. 9 (a), CHCl _{3 is used} , and in FIG. 9 (b), NMP (1-methyl-2- Pyrrolidone) is used as the organic solvent. From such a TEM photograph, it can be understood that the dispersion obtained by the production method of the present invention contains single-walled carbon nanotubes from which the bundle is dissociated. In addition, from this TEM photograph, the effect of the vibration pulverization treatment performed by the production method of the present invention is only effective to dissociate the carbon nanotube bundles if not completely (the carbon nanotubes are removed by the vibration treatment). It is understood that the bundle is at least dissociated because it is thin from the original form / shape), and there is no effect of destroying the structure of the carbon nanotube itself.

[Comparison experiment of manufacturing method of the present invention and conventional ultrasonic method]
In order to confirm the effect of the vibration pulverization treatment performed by the production method of the present invention by comparison with the prior art, two production methods of the present invention and the ultrasonic method were carried out.
(1) Production of carbon nanotube dispersion by the production method of the present invention NMP (1-methyl-2-pyrrolidone), DMF (N, N-dimethylformamide), CHCl ₃ (chloroform), DMSO (dimethyl sulfoxide) as organic solvents A carbon nanotube dispersion liquid (sample A) was produced by the production method of the present invention using each of these. In particular,
(I) 1 mg of single-walled carbon nanotubes (manufactured by Carbon Nanotechnologies Incorporated), 5 mg of dispersant (specifically polythiophene) and two agate balls (sphere diameter 5 mm), 20 mm bottom diameter, 65 mm longitudinal length (The cylindrical hollow part formed in the said container: The cross-sectional diameter of the trunk | drum is 12 mm, and the length of a longitudinal direction is 50 mm).
(Ii) In a vibrator (made by Retsch, MM200), with the longitudinal direction of the hermetic container hollow portion being almost horizontal, the hermetic container is moved horizontally with an amplitude of about 30 mm and a frequency of about 30 s ^−1. Was reciprocated.
(Iii) After reciprocating the sealed container for about 20 minutes, the black powder was taken out from the sealed container hollow part.
(Iv) By adding about 1 mL of an organic solvent to about 6 mg of the obtained black powder, a dispersion A containing a single-walled carbon nanotube stably was obtained (the precipitate of the single-walled carbon nanotube was centrifuged (Removed from the aqueous solution by separation (18000 rpm, 20 minutes, about 25 ° C. (room temperature))).
(2) Implementation of ultrasonic method An attempt was made to produce a carbon nanotube dispersion by the conventional ultrasonic method. The organic solvent was sampled using NMP (1-methyl-2-pyrrolidone), DMF (N, N-dimethylformamide), CHCl ₃ (chloroform), DMSO (dimethyl sulfoxide), respectively, as in the production method of the present invention described above. B was prepared. The operating method and experimental conditions are as follows.
(I) First, 1.0 mg of single-walled carbon nanotubes (manufactured by Carbon Nanotechnologies Incorporated) and 5 mg of a dispersant (specifically polythiophene) are charged into a 10 mL glass vial, and then about 1 mL of an organic solvent is charged. To obtain a mixture.
(Ii) The mixture obtained in (i) was subjected to sonication for 90 minutes using an ultrasonic bath (40 W, 42 KHz, 5510 Branson Ultrasonic Corp.).
(Iii) Thereafter, the mixture obtained in (ii) was charged into a microcentrifuge tube (Eppendorf AG), subjected to centrifugation, and the precipitate was removed to obtain Sample B.
(3) Results For sample A obtained by the production method of the present invention and sample B obtained by the ultrasonic method, the carbon nanotube concentration was calculated from the absorbance (A ₅₀₀ ) at a wavelength of 500 nm in the visible absorption spectrum (Example) 3). The results are shown in Table 3.

Referring to Table 3, sample A obtained by the production method of the present invention contains carbon nanotubes, whereas sample B does not contain carbon nanotubes except for CHCl ₃ conditions. I understand. From this, it is possible to grasp that carbon nanotubes are not dispersed only by a dispersant and / or an organic solvent, and that carbon nanotubes are dispersed only after vibration pulverization treatment. It was understood that the effect was excellent. It should be noted that the vibration pulverization treatment has a particularly advantageous effect on the dissociation of the bundle of carbon nanotubes because, unlike ultrasonic treatment, a large shearing force acts directly on the carbon nanotubes. It is done.

  The carbon nanotube dispersion obtained by the production method of the present invention is used for the production of gas storage products (for example, hydrogen storage media for storing hydrogen gas fuel such as cars or ships) or electrodes (negative electrodes used in lithium secondary batteries). Not only can it be used, it can also be used for the manufacture of emitters for field emission displays, photoelectric conversion elements or cosmetics.

Claims (19)

A method for producing a dispersion comprising carbon nanotubes, comprising: (i) subjecting carbon nanotubes and a cyclic organic compound to vibration pulverization at a frequency of 5 to 120 s ⁻¹ to obtain a carbon nanotube mixture; and
(ii) adding an organic solvent to the carbon nanotube mixture to obtain a dispersion containing carbon nanotubes, wherein the cyclic organic compound used in step (i) have a soluble Te,
A method for producing a carbon nanotube dispersion, wherein the cyclic organic compound is polyvinylpyrrolidone or polythiophene . The method according to claim 1, wherein after the carbon nanotube, the cyclic organic compound, and the hard sphere are provided in the container, the vibration pulverization is performed by vibrating the hard sphere with respect to the container. By reciprocating the container in a certain direction, the hard sphere is vibrated with respect to the container, and the ratio W between the amplitude W _b when the container is reciprocated and the container hollow portion length L _b in the direction of reciprocating the container _{b: L b} is 1: 1.3 to 15: characterized in that it is a 1, method of claim 2. The method according to claim 2, wherein the number of hard spheres is 1 to 6, and the ratio of the total volume of the hard spheres to the volume of the hollow portion of the container is 0.5 to 10%. The method according to claim 1, further comprising polystyrene sulfonate as the cyclic organic compound . The method according to claim 1, wherein the polythiophene is a π-based compound . The method according to claim 6, wherein the π-based compound is a polythiophene derivative . The method according to claim 1, wherein the organic solvent is an alcohol, an ether organic solvent, an amide organic solvent, a sulfoxide, or a halogen organic solvent. 9. A process according to claim 8, characterized in that the alcohol is selected from the group consisting of methanol, ethanol, isopropanol and t-butanol. The method according to claim 8, characterized in that the ether organic solvent is selected from the group consisting of diethyl ether and tetrahydrofuran. The method according to claim 8, characterized in that the amide-based organic solvent is selected from the group consisting of 1-methyl-2-pyrrolidone and N, N-dimethylformamide. The method according to claim 8, characterized in that the sulfoxide is dimethyl sulfoxide. 9. A process according to claim 8, characterized in that the halogenated organic solvent is selected from the group consisting of chloroform, methylene chloride and 1,1,2,2-tetrachloroethane. The method according to claim 1, characterized in that the frequency is 20-50 s- ¹ . The method according to claim 1, wherein the vibration grinding is performed for 2 minutes to 2 hours. The method according to claim 1, wherein in the step (i) of obtaining the carbon nanotube mixture, the carbon nanotube bundle is at least partially dissociated. The method according to claim 1, wherein in the step (ii) of obtaining a dispersion, an organic solvent is added to the carbon nanotube mixture, and then the resulting mixture is subjected to centrifugation. Filtering the supernatant obtained by subjecting to the centrifugation, and further adding a solvent consisting of the same main component as the organic solvent to the resulting residue, and a membrane filter used for filter filtration in the supernatant The process according to claim 17, characterized in that 5-95% of the carbon nanotubes contained are recovered. In the step (ii) of obtaining a dispersion, an organic solvent is added to the carbon nanotube mixture, the resulting mixture is subjected to centrifugation, and the precipitate in the mixture is collected, and the organic solvent and the precipitate are separated from the precipitate. wherein the addition of solvent of the same main component, the method of claim 1.