JP6940058B2 - Carbon nanotube aggregate - Google Patents

Description

The present invention relates to an aggregate of carbon nanotubes in which carbon nanotube molecules are aggregated. For example, it relates to an aggregate of carbon nanotubes having a three-dimensional shape.

Carbon nanotubes (hereinafter referred to as CNT) are substances having a cylindrical main skeleton composed of only carbon atoms, and are excellent in electrical properties, thermal conductivity, and mechanical properties. CNT is a material that is extremely lightweight and extremely tough, and at the same time has excellent elasticity and resilience. CNTs having such properties are extremely attractive and important substances as industrial materials. For example, a flat substrate and CNTs vertically oriented on the flat substrate can be applied as a dry adhesive sheet (see Non-Patent Document 1).

CNTs can be synthesized by growing CNTs while vertically orienting them on a substrate such as silicon or silicon oxide. CNTs are easily aggregated by the van der Waals force between molecules, and usually, a plurality of CNT molecules form a bundle (hereinafter referred to as a bundle, hereinafter referred to as a bundle or a CTN bundle) or an aggregate. The bundle further forms an aggregate and provides a CNT aggregate in the form of flakes, powders, granules, flakes, or blocks (see Patent Documents 1 and 2).

JP-A-2010-159209 Japanese Unexamined Patent Publication No. 2014-131960

Lianty Cue, et al., "Science", United States, 2008, Vol. 322, p. 238-242

An object of the present invention is to provide a substrate and a CNT aggregate having a bundle that grows on the substrate and has a large distribution of length and thickness. Alternatively, it is an object of the present invention to provide a CNT molded body having a bundle having a large distribution of length and thickness, and a CNT dispersion containing the same. Alternatively, an object of the present invention is to provide a method for producing these CNT aggregates.

One of the embodiments of the present invention is a carbon nanotube aggregate having a particulate base material and a bundle of carbon nanotubes on the base material. The angles between adjacent bundles are distributed in the range of 58 ° or more and 180 ° or less. The standard deviation of the angle may be 15 ° or more and 45 ° or less.

The area occupancy of the bundle may be 40% or more and 85% or less. Alternatively, the standard deviation of the area occupancy of the bundle may be 4% or more and 10% or less.

The diameter of the bundle may be distributed in the range of 80 μm or more and 320 μm or less. Alternatively, the standard deviation of the bundle diameter may be 40 μm or more and 90 μm or less.

The length of the bundle may be distributed in the range of 400 μm or more and 675 μm or less. Alternatively, the standard deviation of the bundle length may be 40 μm or more and 100 μm or less.

One of the embodiments of the present invention is an aggregate of carbon nanotubes containing a bundle of carbon nanotubes having a diameter of 40 μm or more and 200 μm or less and a length of 110 μm or more and 485 μm or less. be.

The standard deviation of the length may be 60 μm or more and 100 μm or less. The standard deviation of the diameter may be 20 μm or more and 50 μm or less.

One of the embodiments of the present invention is a method for producing carbon nanotube aggregates. The production method is to form a catalyst layer on the base material while stirring the spherical base material in a chamber that rotates at a speed of 5 rpm or more and 10 rpm or less, and carbon nanotubes by the chemical vapor deposition method while heating the base material. Includes growing on the catalyst layer.

It is possible to provide a CNT aggregate having a bundle having a large distribution of length and thickness in one pot. Thereby, it is possible to provide a CNT aggregate, a CNT molded body, and a CNT dispersion which are excellent in adhesiveness and can be easily combined with various materials.

The schematic diagram of one CNT aggregate of embodiment. Schematic of a bundle of one CNT aggregate, a CNT molded body, and a catalyst carrier of the embodiment. Optical microscope images of the CNT aggregates of Example 1 and Comparative Example 1. An optical microscope image of the CNT aggregate of Example 1. Histogram of angles between adjacent bundles in the CNT aggregates of Example 1 and Comparative Example 1. Angle distribution between adjacent bundles in the CNT aggregates of Example 1 and Comparative Example 1. Optical microscope images of the CNT aggregates of Example 1 and Comparative Example 1. Histogram of the area occupancy of the bundle in the CNT aggregate of Example 1 and Comparative Example 1. Distribution of the area occupancy of the bundle in the CNT aggregates of Example 1 and Comparative Example 1. Optical microscope images of the CNT aggregates of Example 1 and Comparative Example 1. An optical microscope image of the CNT aggregate of Example 1 and a schematic view thereof. Diameter distribution of bundles of CNT aggregates of Example 1 and Comparative Example 1. Diameter distribution of bundles of CNT aggregates of Example 1 and Comparative Example 1. Bundle length distribution of CNT aggregates of Example 1 and Comparative Example 1. Bundle length distribution of CNT aggregates of Example 1 and Comparative Example 1.

Hereinafter, embodiments of the invention disclosed in this application will be described with reference to the drawings. However, the present invention can be implemented in various forms without departing from the gist thereof, and is not construed as being limited to the description contents of the embodiments exemplified below.

In the present specification and claims, the CNT aggregate is a base material, a CNT bundle that grows on the base material, a CNT molded body obtained by peeling the CNT bundle from the base material, and a CNT molded body. Contains a CNT dispersion liquid dispersed in a solvent.

The drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual embodiment in order to clarify the explanation, but this is merely an example and the interpretation of the present invention is limited. It's not something to do. In this specification and each figure, elements having the same functions as those described with respect to the above-mentioned figures may be designated by the same reference numerals and duplicate description may be omitted.

Other effects different from those brought about by the following embodiments, which are obvious from the description of the present specification or which can be easily predicted by those skilled in the art, are naturally according to the present invention. It is understood to be brought about.

(Embodiment)
[1. structure]
FIG. 1A shows a schematic diagram of the CNT aggregate 100 of the present embodiment. The CNT aggregate 100 has a base material 102 having a curved surface, and a bundle 104 of a plurality of CNTs grown on the base material 102. The base material 102 can take a particle-like shape, and in this case, the base material 102 may have a spherical shape or an elliptical cross section. CNTs grow from a part of the surface of the base material 102. Therefore, a part of the surface of the base material 102 does not have to be exposed and covered with the bundle 104. The length, thickness (diameter), and growth direction of the bundle 104 vary, and there are bundles 104 having various lengths and diameters on the surface of one base material 102.

A schematic cross-sectional view of the CNT aggregate 100 is shown in FIG. 1 (B). As shown in FIG. 1 (B), the angle θ between two adjacent bundles 104 can be defined by using the direction in which the bundle 104 extends toward the center of the base material 102. Focusing on one CNT aggregate 100, the angle (angle between bundles) θ can be, for example, 58 ° or more and 180 ° or less. The inter-bundle angles are widely distributed within the above range, for example, the combination of bundles 104 forming a 58 ° inter-bundle angle, the combination of bundles 104 forming a 180 ° inter-bundle angle, and 180 ° greater than 58 °. Combinations of bundles 104 that form less than an angle between bundles may be present simultaneously in one CNT aggregate 100.

Alternatively, in one CNT aggregate 100, the average angle between bundles is 75 ° or more and 125 ° or less, 90 ° or more and 110 ° or less, or 95 ° or more and 105 ° or less, and the standard deviation is 15 ° or more and 45 ° or less. Alternatively, it may be 20 ° or more and 30 ° or less.

As shown in FIG. 1 (C), in the plan projection view of the CNT aggregate 100, the ratio of the area occupied by the bundle 104 in the circle 106 to the area of the smallest circle 106 including all the bundles 104 is Defined as area occupancy. The area occupancy rate has a wide distribution and can take a value of 40% or more and 85% or less. For example, an aggregate containing a plurality of CNT aggregates 100 includes a CNT aggregate 100 having an area occupancy of 40%, a CNT aggregate 100 having an area occupancy of 85%, and a CNT aggregate 100 having an area occupancy of more than 40% and less than 85% at the same time. Can be contained.

Alternatively, in an aggregate containing a plurality of CNT aggregates 100, the average area occupancy is 50% or more and 80% or less, 60% or more and 70% or less, or 65% or more and 70% or less, and the standard deviation is 4. It may be% or more and 10% or less, or 6% or more and 8% or less.

The size of each bundle 104 is defined by a thickness (diameter) D and a length L, as shown in FIG. 2 (A). In the aggregate containing the plurality of CNT aggregates 100, the diameter D of the bundle 104 can be, for example, 80 μm or more and 320 μm or less when the bundle 104 is bonded to the base material 102, and is widely distributed in this range. For example, an aggregate containing a plurality of CNT aggregates 100 may simultaneously contain a bundle 104 having a diameter D of 80 μm, a bundle 104 having a diameter D of 320 μm, and a bundle 104 having a diameter D greater than 80 μm and less than 320 μm. can.

Alternatively, in an aggregate containing a plurality of CNT aggregates 100, the average diameter D is 140 μm or more and 260 μm or less, 160 μm or more and 240 μm or less, or 180 μm or more and 220 μm or less, and the standard deviation is 40 μm or more and 90 μm or less, or 55 μm. It may be 75 μm or more and 75 μm or less.

In the aggregate containing the plurality of CNT aggregates 100, the length L of the bundle 104 is, for example, 400 μm or more and 675 μm or less when the bundle 104 is bonded to the base material 102, and is widely distributed in this range. For example, an aggregate containing a plurality of CNT aggregates 100 simultaneously includes a bundle 104 having a length L of 400 μm, a bundle 104 having a length L of 675 μm, and a bundle 104 having a length L greater than 400 μm and less than 675 μm. be able to.

Alternatively, in an aggregate containing a plurality of CNT aggregates 100, the average length L is 300 μm or more and 750 μm or less, 400 μm or more and 650 μm or less, or 500 μm or more and 600 μm or less, and the standard deviation is 40 μm or more and 100 μm or less, 50 μm. It may be 90 μm or more, or 60 μm or more and 80 μm or less.

By peeling the bundle 104 from the base material 102, a CNT molded body 110 (see FIG. 2B) containing the plurality of bundles 104 can be obtained. As described above, the CNT molded body 110 that does not include such a base material 102 is also included in the CNT aggregate, which is one of the present embodiments. The diameter D of the bundle 104 of the CNT molded body 110 can be 40 μm or more and 200 μm. Due to the variation in the diameter D of the bundle 104 of the CNT aggregate 100, the diameter D of the bundle 104 of the CNT molded body 110 also has a large distribution, and is widely distributed in the above-mentioned range. For example, the CNT molded body 110 can simultaneously contain a bundle 104 having a diameter D of 40 μm, a bundle 104 having a diameter D of 200 μm, and a bundle 104 having a diameter D larger than 40 μm and 200 μm or less.

Alternatively, the average diameter D of the bundle of the CNT molded article 110 is 60 μm or more and 140 μm or less, 80 μm or more and 120 μm or less, or 90 μm or more and 110 μm or less, and the standard deviation of the diameter D is 20 μm or more and 50 μm or less, or 30 μm or more and 40 μm or less. It may be.

Similarly, due to the variation in the length L of the bundle 104 of the CNT aggregate 100, the length L of the bundle 104 of the CNT molded body 110 also has a large distribution, and is widely distributed in the range of 110 μm or more and 485 μm or less. .. For example, the CNT molded body 110 can simultaneously include a bundle 104 having a length L of 110 μm, a bundle 104 having a length L of 485 μm, and a bundle 104 having a length L greater than 110 μm and less than 485 μm.

Alternatively, the average length L of the bundle 104 of the CNT molded body 110 is 200 μm or more and 350 μm or less, or 200 μm or more and 300 μm or less, and the standard deviation is 60 μm or more and 100 μm or less, 70 μm or more and 90 μm or less, or 70 μm or more and 85 μm or less. There may be. When the bundle 104 is peeled off from the base material 102, the structure of the bundle 104 changes for some reason. Therefore, the average value and standard deviation of the diameter D and the length L of the bundle 104 of the CNT molded body 110 are the CNT aggregates. May differ from those of 100 bundles 104.

[2. Manufacturing method]
In the above-mentioned CNT aggregate 100, as shown in FIG. 2C, the catalyst layer 122 is formed non-uniformly or partially on the surface of the base material 102 to prepare the catalyst carrier 120, and the catalyst is formed. It can be produced by growing CNTs by applying a thermochemical vapor deposition method (thermal CVD method) using the layer 122.

As the base material 102, metal oxides such as aluminum oxide, zinc oxide, and zirconium oxide can be used. The particle size of the base material 102 can be arbitrarily determined, and can have an average particle size selected from the range of, for example, 0.1 mm to 50 mm, 0.1 mm to 20 mm, or 0.1 mm to 10 mm.

The catalyst layer 122 may contain one or more metals such as Fe, Co, and Ni. At least a part of the metal exists in the catalyst layer 122 in a zero-valent state. By performing sputtering (for example, high-frequency magnetron sputtering) on the target containing the metal while stirring the base material 102 in a chamber rotated at a speed of 5 rpm to 10 rpm, the base material 102 is non-uniform on the surface of the base material 102. A catalyst carrier 120 having a catalyst layer 122 formed therein is obtained. The thickness of the catalyst layer 122 can be 1 nm or more and 10 nm or less, or 1 nm or more and 3 nm or less, typically 1.8 nm. The catalyst layer 122 may be formed by, for example, a vacuum vapor deposition method, an organometallic CVD (MOCVD) method, or the like, in addition to the sputtering method. Before sputtering the metal, a metal oxide such as aluminum oxide may be formed on the base material 102 by a sputtering method or the like. In this case, the catalyst layer 122 has a structure in which a metal oxide layer and a metal layer are laminated.

The CNT bundle 104 is a catalyst carrier 120 in the temperature range of 600 ° C to 1200 ° C in the presence of CNT growth gases such as benzene, acetylene, carbon monoxide, methane and ethanol, and catalyst activators such as water. It can be formed by heating and growing CNTs. At this time, an inert gas such as helium or argon may be supplied to dilute the gas for CNT growth. By the above steps, the CNT aggregate 100 can be produced.

The base material 102 can be dissolved by treating the obtained CNT aggregate 100 with, for example, an acidic or basic solvent. As a result, the bundle 104 is peeled off from the base material 102, and the CNT molded body 110 can be obtained. Examples of the acidic solvent include an aqueous solution of an ammonium salt such as ammonium chloride and ammonium perchlorate, and an inorganic acid such as hydrochloric acid and sulfuric acid.

Usually, the CNT aggregate is produced by uniformly forming a catalyst layer on a substrate such as silicon or silicon oxide, and then growing the CNTs. This makes it possible to produce CNT aggregates having bundles having a small diameter and length distribution in one pot (that is, one synthesis process). This is because CNTs grow and orient vertically from the catalyst surface by uniformly forming the catalyst, and the growth start and end occur simultaneously on almost all catalyst surfaces. In other words, in order to produce CNT aggregates having various diameters and lengths, that is, CNT aggregates having a large diameter and length distribution (standard deviation), the CNTs formed under various conditions are mixed. There is a need. On the other hand, by applying the present embodiment, it is possible to efficiently produce a CNT aggregate having a large diameter and length distribution in one pot. Therefore, it is possible to provide a CNT molded body or a CNT dispersion having a large diameter and length distribution at low cost.

In general, a material having a molecular weight distribution is easier to mix with a solvent or other material than a material having a uniform molecular weight (length or diameter), and it is easier to form a uniformly mixed composite material. Further, for example, when CNTs having different diameters and lengths are formed on the surface of the base material, it is expected that the dry adhesive strength is improved by the anchor effect. Therefore, by using the CNT aggregate 100 of the present embodiment, various composite materials including CNT can be easily provided. Alternatively, it becomes possible to provide a dry adhesive having high dry adhesive strength.

In this embodiment, a production example and characteristic evaluation of the CNT aggregate 100 and the CNT molded body 110 will be described.

[1. Base material]
A zirconia spherical base material (manufactured by Tosoh, diameter 0.5 mm to 5.0 mm) was used as the base material 102.

[2. Cleaning of spherical substrate]
Each spherical substrate was washed to remove dirt and impurities on the surface. The cleaning was carried out by repeating ultrasonic irradiation with an ultrasonic cleaner (manufactured by Sharp, UT-106) in a neutral detergent or acetone, and then repeating washing with distilled water until the cleaning liquid could be completely removed. The washed spherical substrate was dried in air at 120 ° C. for 24 hours in a constant temperature bath to completely remove water. It has already been confirmed by the inventors that the type of cleaning liquid does not affect the growth of CNTs.

[3. Formation of catalyst layer]
10 g to 500 g of a zirconia spherical substrate was introduced into a rotary catalyst vapor deposition apparatus (MSS-700 manufactured by ISYS), and then the inside of the apparatus chamber was depressurized by a ^{vacuum pump to 1.0 × 10 -4 Pa or less.} After that, oxygen and argon gas are introduced into the chamber, and aluminum is sputtered for 1000 seconds or more while uniformly stirring the spherical base material at a chamber rotation speed of 1 rpm to 10 rpm to obtain an alumina thin film (thickness) on the spherical base material. 15 nm or more) was formed. Subsequently, in an argon atmosphere, the iron thin film (thickness of about 1.8 nm) was laminated on the alumina thin film by sputtering iron for 240 seconds while rotating the chamber at the same rotation speed as when the alumina thin film was formed. / An iron thin film was formed on a spherical substrate. As a result, the catalyst carrier 120 is obtained, and the alumina thin film / iron thin film functions as the catalyst layer 122.

[4. Growth of CNT]
The obtained catalyst carrier 120 (1.0 g to 10 g) was placed in a boat-shaped sample holder made of a stainless steel mesh having a wire diameter of 0.1 mm to 0.8 mm and a mesh number of 10 to 100 meshes / inch. The sample holder was introduced into an 80 mmφ quartz tube in an electric furnace. While introducing a mixed gas of helium / hydrogen into a heated quartz tube, the surface of the catalyst layer 122 is reduced and given a particulate form, and then helium / growth activator (water) / ethylene is added at 810 ° C. By introducing in the above, CNTs were grown on the spherical base material. Samples prepared using the catalyst carrier 120 obtained by setting the chamber rotation speed to 3 rpm and 5 rpm are referred to as Comparative Example 1 and Example 1, respectively.

[5. Evaluation of catalyst layer uniformity]
The CNT aggregate 100 produced by the above method was observed with a digital microscope (manufactured by KEYENCE, VHX-5000, the same applies hereinafter). Specifically, a spherical base material on which CNTs were grown was adhered to a silicon base material using a double-sided tape to prepare an observation sample, and observation was performed at a magnification of 20 to 200 times.

3 (A) and 3 (B) show optical microscope images of Example 1 and Comparative Example 1, respectively. Compared with the case of Comparative Example 1, the CNT aggregate 100 of Example 1 is non-uniform because the growth of CNTs does not occur on the entire spherical substrate. This indicates that the catalyst layer 122 of Example 1 is formed non-uniformly as compared with that of Comparative Example 1.

[6. Evaluation of CNT bundle]
<6-1. Angle between bundles>
The angle between bundles was evaluated based on an optical microscope image as an index for comparing the growth direction of CNTs on a spherical substrate. The optical microscope observation was performed in the same manner as described above, and the angle between bundles was measured using the analysis tool attached to the digital microscope. FIG. 4 shows an example of measuring the angle between bundles. The smaller the angle between the bundles, the more the CNTs grow so that the bundles 104 are closer together, that is, the bundles 104 grow uniformly on the spherical substrate.

The histogram of the angle between bundles in Comparative Example 1 and Example 1 is summarized in FIG. 5, and the distribution of the angle between bundles is summarized in FIG. As shown in FIGS. 5 and 6, in Comparative Example 1, the distribution of the angle between bundles is narrow, the average angle is 19 °, and the minimum angle is 9 ° to the maximum angle of 36 °. On the other hand, in Example 1, the angle between bundles is 101 ° on average, and is widely distributed in the range from the minimum angle of 58 ° to the maximum angle of 180 °, and the distribution of the angle between bundles is compared with that of Comparative Example 1. It is clearly increasing. This is clear from the fact that the standard deviation of the angle between bundles in Comparative Example 1 is 6 °, whereas that in Example 1 is as large as 28 °. Compared to Comparative Example 1 in which the catalyst layer 122 is uniformly formed on the spherical base material, in Example 1 in which the catalyst layer 122 is formed non-uniformly, the angle between bundles is large, so that the catalyst on the spherical base material is used. It is suggested that the uniformity of the layer 122 affects the growth direction of the CNT with respect to the surface of the base material 102.

<6-2. Area occupancy>
The uniformity of the growth direction of CNTs on the spherical substrate was evaluated by the area occupancy. The area occupancy was evaluated using the above-mentioned optical microscope image. 7 (A) and 7 (B) show optical microscope images of the CNT aggregate 100 of Example 1 and Comparative Example 1, respectively. The area occupancy was calculated according to the following method using the analysis tool attached to the digital microscope. First, as shown in FIGS. 7 (A) and 7 (B), the smallest circle including all the bundles 104 was drawn in the optical microscope image, and the area thereof was determined. Next, the area of the CNT bundle existing in the circle was measured. The area ratio of the CNT bundle to the area of the circle (100 × [(area of the CNT bundle in the circle) / (area of the circle)]) was calculated as the area occupancy rate (%). The number of samples (number of spherical substrates) used in the calculation was 20 to 30.

The histograms of the area occupancy rates in Comparative Example 1 and Example 1 are shown in FIG. 8, and the distribution of the area occupancy rates is summarized in FIG. In the case of Comparative Example 1, the distribution of the area occupancy is narrow, the average is 96%, and it is within a narrow range from the minimum area occupancy of 92% to the maximum area occupancy of 99%. On the other hand, in Example 1, the average area occupancy rate was as low as 67%, and it was distributed in a wide range from the minimum area occupancy rate of 48% to the maximum area occupancy rate of 81%. Is clearly decreasing and the distribution is increasing. This is clear from the fact that the standard deviation of the area occupancy rate of Comparative Example 1 is 2.3%, whereas the standard deviation of the area occupancy rate of Example 1 is as large as 7.3%. be. This result also shows that the growth direction of CNTs in Example 1 is random as compared with Comparative Example 1 because the catalyst layer is formed in a non-uniform manner.

<6-3. Diameter, length>
The uniformity of CNT growth on the spherical substrate was evaluated by the diameter and length of the bundle 104. The evaluation was performed on the bundle 104 of the CNT aggregate 100 and the bundle 104 of the CNT molded body 110 obtained by peeling the bundle 104 from the spherical substrate. The evaluation was performed using the above-mentioned optical microscope image and the analysis tool attached to the digital microscope. 10 (A) and 10 (B) show optical microscope images of the CNT aggregate 100 of Example 1 and Comparative Example 1, respectively. Further, FIGS. 11 (A) and 11 (B) show an optical microscope image of the CNT molded body 110 of Example 1 and a schematic view thereof, respectively. Here, the diameter and length of the bundle 104 correspond to the thickness of the bundle 104 in the direction parallel to the surface of the spherical base material and the height of the bundle 104 in the direction perpendicular to the surface of the spherical base material, respectively. do. In calculating the diameter and length, bundles 104 from 75 to 100 were used in both Example 1 and Comparative Example 1.

Histograms of the diameters of the bundle 104 of the CNT aggregate 100 and the bundle 104 of the CNT molded body 110 are shown in FIGS. 12 and 13, respectively. As shown in FIG. 12, in Example 1, the diameter is distributed in the range of 80 μm or more and 320 μm or less (range width: 240 μm), and when attention is paid to the bundle 104 existing at a normalization frequency of 5% or more, the diameter thereof. The distribution range of was 100 μm or more and 260 μm or less (range width: 160 μm). On the other hand, in Comparative Example 1, the distribution range of the diameter of the bundle 104 existing at a normalization frequency of 5% or more is 20 μm or more and 80 μm or less (range width: 60 μm), and the distribution range of Example 1 is that of Comparative Example 1. It was about twice that. In fact, the standard deviation of the diameter of the bundle 104 in Comparative Example 1 was 27 μm, whereas that in Example 1 was 65 μm.

It was confirmed that the diameter of the bundle 104 of the CNT molded body 110 of Example 1 also has a large distribution due to the large diameter distribution of the bundle 104 of the CNT aggregate 100. Specifically, as shown in FIG. 13, in Example 1, the diameter of the bundle 104 is distributed in a range of 40 μm or more and 200 μm or less (range width: 160 μm, standard deviation: 35 μm), and the normalization frequency is 5% or more. Focusing on the existing bundle 104, the diameter distribution range was 40 μm or more and 160 μm or less (range width: 120 μm). On the other hand, in Comparative Example 1, this distribution range was 10 μm or more and 70 μm or less (range width: 60 μm, standard deviation: 17 μm). From these results, it was found that the non-uniform formation of the catalyst layer 122 made the growth direction of CNTs random, and the bundle 104 had a large diameter distribution.

A similar tendency was confirmed for the length of the bundle 104. Histograms of the lengths of the bundle 104 of the CNT aggregate 100 and the bundle 104 of the CNT molded body 110 are shown in FIGS. 14 and 15, respectively. As shown in FIG. 14, in Comparative Example 1, the distribution range of the length of the bundle 104 existing at a normalization frequency of 5% or more was 300 μm or more and 400 μm or less (range width: 100 μm, standard deviation: 29 μm). On the other hand, in Example 1, the length of the bundle 104 is distributed in the range of 400 μm or more and 675 μm or less (range width: 275 μm, standard deviation: 73 μm), and the bundle 104 having a normalization frequency of 5% or more. Note that the length distribution range was 450 μm or more and 675 μm or less (range width: 225 μm).

Similarly, as shown in FIG. 15, in the bundle 104 of the CNT molded body 110, the length is distributed in the range of 110 μm or more and 485 μm or less (range width: 375 μm, standard deviation: 79 μm) in Example 1, and the standardization frequency. Focusing on the bundle 104 in which 5% or more is present, the length is distributed in the range of 175 μm or more and 400 μm or less. On the other hand, in Comparative Example 1, it was found that the distribution was in the range of 85 μm or more and 215 μm or less (range width: 130 μm, standard deviation: 30 μm).

Although details are omitted, it was confirmed that the same result can be obtained by using an alumina spherical base material (manufactured by Daimei Chemical Co., Ltd., diameter 0.5 mm to 5.0 mm) instead of the zirconia spherical base material.

The result described in this example shows that the catalyst layer is formed non-uniformly, so that the catalyst size and the catalytic activity become non-uniform. Therefore, the growth direction of the CNTs becomes random on the catalyst carrier 120, and this is the CNTs. It suggests that it contributes to growth heterogeneity. Furthermore, these results indicate that under the same CNT growth conditions, CNTs with a large distribution of length and diameter can be synthesized in one pot.

100: CNT aggregate, 102: base material, 106: circle, 104: bundle, 110: CNT molded body, 120: catalyst carrier, 122: catalyst layer

Claims (7)

Particle-like base material and
A catalyst layer partially laminated on the substrate and
It has a bundle of carbon nanotubes grown from the catalyst layer on the substrate.
An aggregate of carbon nanotubes distributed in a range where the angle between adjacent bundles is 58 ° or more and 180 ° or less. The carbon nanotube aggregate according to claim 1, wherein the area occupancy of the bundle is 40% or more and 85% or less. The carbon nanotube aggregate according to claim 1, wherein the bundle has a diameter of 80 μm or more and 320 μm or less. The carbon nanotube aggregate according to claim 1, wherein the length of the bundle is distributed in a range of 400 μm or more and 675 μm or less. An aggregate of carbon nanotubes in which the diameter of the bundle is distributed in the range of 40 μm or more and 200 μm or less, and the standard deviation of the diameter is 20 μm or more and 50 μm or less. An aggregate of carbon nanotubes in which the length of the bundle is distributed in the range of 110 μm or more and 485 μm or less, and the standard deviation of the length is 60 μm or more and 100 μm or less. The carbon nanotube aggregate according to claim 1, wherein the standard deviation of the angle is 15 ° or more and 45 ° or less.

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