TW201925084A - Carbon nanotube growth substrate and carbon nanotube production method - Google Patents

Abstract

The purpose of the present invention is to not cause cracking in an intermediary layer when heating a carbon nanotube growth substrate to a carbon nanotube growth temperature, even when heating at a high heating rate. This carbon nanotube growth substrate (1) is provided with a base material (2) formed from a metal, a silica layer (3) formed on the surface of the base material (2) and containing silicon oxide, and a catalyst layer (4) formed on the surface of the silica layer (3) opposite the side of the base material (2). Represented by the compositional formula SiOx, the siliconoxide in the silica layer (3) has an x value less than 2.

Description

Substrate for carbon nanotube growth and method for producing carbon nanotube

The present invention relates to a substrate for carbon nanotube growth for use in the production of a carbon nanotube.

Carbon nanotubes have attracted attention as materials having excellent electrical conductivity, thermal conductivity, and mechanical strength, and are used in various fields. As a method of producing the carbon nanotube, a chemical vapor deposition (CVD: Chemical Vapor Deposition) method is used. For example, Patent Document 1 and Patent Document 2 disclose a method of manufacturing a carbon nanotube by a CVD method using a substrate for carbon nanotube growth, wherein the substrate for carbon nanotube growth is made of metal. The substrate, an intermediate layer made of aluminum, ruthenium, ruthenium dioxide or the like, and a catalyst layer formed on the surface of the intermediate layer opposite to the substrate side.

Conventional technology literature

Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-70137

Patent Document 2: Japanese Laid-Open Patent Publication No. 2013-1598

(1) Technical problems to be solved

However, in the techniques disclosed in Patent Document 1 and Patent Document 2, the intermediate layer is made of aluminum, tantalum, cerium oxide or the like. Therefore, when the carbon nanotube growth substrate is heated to the carbon nanotube growth temperature, if it is heated at a high temperature increase rate (for example, 400 ° C / min or more), the metal as the substrate is rapidly thermally expanded. Cracks are generated in the intermediate layer (refer to Fig. 10). As a result, in the substrate for carbon nanotube growth in which the crack occurred, the carbon nanotube produced was defective at the position where the crack occurred, and the carbon nanotube could not be produced satisfactorily. In other words, in the techniques of Patent Document 1 and Patent Document 2, it is necessary to raise the temperature of the carbon nanotube growth substrate to the carbon nanotube growth temperature at a low temperature increase rate, and there is a problem that productivity is low.

An object of the present invention is to realize a substrate for carbon nanotube growth, which is not heated even when heated at a high temperature increase rate when the carbon nanotube growth substrate is heated to a carbon nanotube growth temperature. The intermediate layer produces cracks.

(2) Technical plan

In order to solve the above problems, a carbon nanotube growth substrate according to an aspect of the present invention includes a substrate made of a metal, an intermediate layer formed on the surface of the substrate and containing ruthenium oxide, and an intermediate layer formed on the intermediate layer. The catalyst layer on the opposite side to the substrate side, the cerium oxide in the intermediate layer is expressed by the structural formula SiO _x , and the value of x is less than 2.

(3) Beneficial effects

According to one aspect of the present invention, an effect is achieved in that a substrate for carbon nanotube growth is realized, and when the carbon nanotube growth substrate is heated to a carbon nanotube growth temperature, heating is performed at a higher temperature increase rate. There is also no crack in the middle layer.

[Embodiment 1]

Next, the carbon nanotube growth substrate 1 according to one embodiment of the present invention will be described in detail. Hereinafter, the carbon nanotube is abbreviated as "CNT".

(Structure of Substrate 1 for Carbon Nanotube Growth)

Fig. 1 is a cross-sectional view showing the structure of a substrate 1 for CNT growth. As shown in FIG. 1, the CNT growth substrate 1 includes a base material 2, a vermiculite layer 3 (intermediate layer), a catalyst layer 4, and a backing layer 5.

The substrate 2 is a film made of metal. The substrate 2 needs to be a metal having heat resistance so that it does not deform due to the heating process described later and the high temperature in the CNT growth process. Specifically, the base material 2 is preferably a stainless steel metal foil, more preferably a metal foil of a ferritic stainless steel (for example, SUS444) having a small thermal expansion coefficient.

The base material 2 is preferably a flexible thickness in order to be in a roll shape in the production of CNTs to be described later. Specifically, in the case where the base material 2 is made of ferritic stainless steel, the thickness of the base material 2 is preferably 10 to 500 μm in order to maintain flexibility. The surface roughness of the substrate 2 is preferably 0.2 to 1 μm. When the surface roughness Ra of the base material 2 is more than 1 μm, the surface roughness of the catalyst layer 4 to be described later increases, and CNT cannot be produced satisfactorily. Further, even if the surface roughness Ra of the substrate 2 is larger than 0.2 μm, there is no large effect, and the processing cost such as polishing increases.

The vermiculite layer 3 is a layer formed on one surface of the substrate 2 and containing cerium oxide (SiO _x ). The vermiculite layer 3 is a layer for preventing diffusion of components such as Cr from the substrate 2 to the catalyst layer 4 to be described later. When a component such as Cr from the substrate 2 diffuses into the catalyst layer 4, the diffused atoms react with the metal constituting the catalyst layer 4, and the catalyst function of the catalyst layer 4 is lowered. Further, by forming the vermiculite layer 3 on the CNT growth substrate 1, the surface of the CNT growth substrate 1 can be made flat. As a result, the atomization of the catalyst metal of the catalyst layer 4 can be promoted.

The vermiculite layer 3 in the present embodiment is composed of cerium oxide (SiO _x ) having a lower oxygen content than cerium oxide (SiO ₂ ). In other words, when the cerium oxide in the vermiculite layer 3 is expressed by the structural formula SiO _x , the value of x is less than 2. Fig. 2(a) is a structural view of cerium oxide (SiO ₂ ), and Fig. 2 (b) is a structural view of cerium oxide constituting the vermiculite layer 3 of the present embodiment.

As shown in Fig. 2(a), cerium oxide is a regular tetrahedral structure in which substantially all of the O atoms are bonded to two Si atoms. On the other hand, as shown in FIG. 2(b), the cerium oxide constituting the vermiculite layer 3 of the present embodiment has a lower bonding ratio of Si atoms and O atoms than cerium oxide, and is also crystallized. A void is formed in the structure. By having this crystal structure, the cerium oxide of the vermiculite layer 3 is more elastic than the cerium oxide (in other words, the rigidity is low). Therefore, the vermiculite layer 3 can expand and contract by the thermal expansion of the base material 2 caused by a sharp temperature rise (specifically, a temperature rise of 700 ° C /min or less) in the heating process described later. Thereby, in the CNT growth substrate 1, it is possible to prevent cracks from being formed on the vermiculite layer 3 in the heating process. As a result, in the CNT growth substrate 1, the CNTs can be favorably grown. In order to further follow the thermal expansion of the substrate 2 caused by a sharp temperature rise in the heating process, the cerium oxide constituting the vermiculite layer 3 is preferably expressed by the structural formula SiO _x and has a value of x of 0.2 or more and 1.4 or less.

3 is a measurement result of the bond energy of the Si 2p orbital of the conventional vermiculite layer by XPS (X-ray photoelectron spectroscopy), and an example of the vermiculite layer of the present invention based on XPS. A graph of the measurement results of the bond energy of the Si2p orbit. As shown in Fig. 3, the peak position of the bond energy of Si in the vermiculite layer of the present invention is lower than the peak position of the bond energy of Si in SiO ₂ (i.e., the bond energy of Si in the case of SiO ₂ ). That is, the vermiculite layer of the present invention is configured such that at least a part of Si is not SiO ₂ but cerium oxide having a smaller oxidation degree than SiO ₂ .

The film thickness of the vermiculite layer 3 is preferably from 150 to 1,500 nm. When the film thickness of the vermiculite layer 3 is more than 1500 nm, cracks are likely to occur in the vermiculite layer 3 at the time of high-temperature treatment (specifically, a heating process and a CNT growth process to be described later). In addition, when the film thickness of the vermiculite layer 3 is less than 150 nm, components such as Cr from the base material 2 are diffused to the catalyst layer 4 to be described later, and the catalyst metal of the catalyst layer 4 cannot be atomized, which is not preferable.

The catalyst layer 4 is a layer formed on the surface of the vermiculite layer 3 on the side opposite to the substrate 2 side. The catalyst layer 4 is a layer containing a metal. The above metal is preferably selected from the group consisting of iron, cobalt, nickel, and alloys of these metals. The film thickness of the catalyst layer 4 is 0.1 to 10 nm.

The backing layer 5 is a layer formed on the surface of the base material 2 opposite to the surface on which the vermiculite layer 3 is formed. The backing layer 5 is composed of cerium oxide having the same composition as that of the cerium oxide constituting the vermiculite layer 3. When the liner layer is not formed on the substrate for CNT growth, in the heating process and the CNT growth process to be described later, since the thermal expansion coefficient of the base material and the vermiculite layer are different, the substrate for CNT growth is curved. On the other hand, by forming the backing layer 5, a layer made of ruthenium oxide is formed on both surfaces of the substrate 2, so that the CNT growth substrate 1 can be prevented from being bent in the heating process and the CNT growth process. In order to suppress the bending of the CNT growth substrate 1 in the heating process and the CNT growth process, it is preferable to control the difference between the film thickness of the liner layer 5 and the film thickness of the vermiculite layer 3 within 100 nm. Further, in one embodiment of the present invention, the structure may be such that a catalyst layer is also formed on the backing layer 5, and CNTs are produced on both surfaces of the substrate for CNT growth.

(Manufacturing Method of Carbon Nanotube Growth Substrate 1)

The manufacturing process of the CNT growth substrate in the present embodiment includes a ruthenium oxide film formation process and a catalyst layer formation process.

The ruthenium oxide film forming process is a process in which a vermiculite layer 3 is formed on one surface of the substrate 2, and a lining layer 5 is formed on the other surface of the substrate 2. The process for forming the vermiculite layer 3 is the same as the process for forming the lining layer 5, and therefore the process for forming the vermiculite layer 3 will be described here.

In the process of forming the vermiculite layer 3 in the present embodiment, a solution method is used. Specifically, a precursor which is a raw material of the vermiculite layer 3 is first applied onto the substrate 2. The precursor is a part of an ethyl group of polyethyl decanoate (partially hydrolyzed condensate of tetraethoxy decane) and methyl triethoxy decane (ethyl ethyl decanoate) as an alkyl alkoxy decane. A solution in which a compound substituted with a methyl group is mixed in a predetermined ratio. Specifically, the ratio specified above is a ratio of methyltriethoxydecane to 100 g of polyethyl phthalate in an amount of from 150 to 900 g.

Next, the precursor applied to the substrate 2 is fired at 500 to 700 ° C for 5 to 60 minutes. Thereby, the precursor is hardened, and the solvent and moisture remaining in the precursor are completely removed. As a result, the vermiculite layer 3 is formed on the surface of the substrate 2.

Here, in the precursor of the present embodiment, as described above, polyethyl decanoate and methyl triethoxy decane are contained. Polyethyl phthalate is calcined to become cerium oxide SiO ₂ . On the other hand, methyltriethoxysilane is calcined to form cerium oxide, but no Si-O-Si bond is formed at a position corresponding to the methyl group (in other words, the cross-linking reaction of the vermiculite is not caused). . Therefore, the vermiculite layer 3 in the present embodiment is composed of cerium oxide having a lower oxygen content than cerium oxide.

Further, in the present embodiment, a method in which polyethyl decanoate and methyltriethoxysilane are used as a precursor is used, but the invention is not limited thereto. In one embodiment of the present invention, polymethyl phthalate may be used as a precursor instead of polyethyl phthalate. Further, as the precursor, tetraethoxydecane or tetramethoxydecane as a monomer may be used instead of polyethyl decanoate. Further, in one embodiment of the present invention, a substance substituted with another functional group such as methyltrimethoxydecane may be used instead of methyltriethoxydecane.

Further, in the present embodiment, the vermiculite layer 3 and the backing layer 5 are formed by a solution method, but the invention is not limited thereto. That is, as long as the cerium oxide constituting the vermiculite layer 3 and the lining layer 5 is cerium oxide having a lower oxygen content than cerium oxide, the strontium layer 3 and the lining layer 5 may be formed by other methods, for example, vapor deposition or The vermiculite layer 3 and the backing layer 5 are formed by sputtering. In the case of using vapor deposition or sputtering, a target or a raw material of SiO may be used, or a target or a raw material in which SiO and SiO ₂ are mixed may be used.

The catalyst layer forming process is a process of forming the catalyst layer 4 on the surface of the vermiculite layer 3 opposite to the substrate 2 side. The catalyst layer forming process is a process of forming a thin film of a metal on the surface of the vermiculite layer 3 opposite to the substrate 2 side by a conventional method such as an EB (Electron Beam) method, a sputtering method, or a solution method.

(Method for Producing Carbon Nanotube Using Carbon Nanotube Growth Substrate 1)

Fig. 4 is a flowchart showing an example of processing of the method for producing CNT according to the embodiment. Fig. 5 is a schematic view of the CNT manufacturing apparatus 30.

As shown in FIG. 4, the manufacturing method of the CNT of the present embodiment includes a heating process S1, a CNT growth process S2 (abbreviation as a growth process), and a post-treatment process S3. Further, as shown in FIG. 5, the CNT manufacturing apparatus 30 includes a substrate supply chamber 31, a heating chamber 32, a reaction chamber 33, a post-processing chamber 34, a substrate winding chamber 35, and a heater 36.

The heating process S1 is a process of heating the CNT growth substrate 1 output from the substrate unwinding device 31A of the substrate supply chamber 31 to the heating chamber 32 to a growth temperature of 600 to 700 ° C using the heater 36. As shown in Fig. 5, the heating chamber 32 includes a chamber 32A and a gas supply port 32B for supplying a gas to the chamber 32A. In the heating process S1, the inside of the chamber 32A is maintained at a predetermined degree of vacuum (several Pa to 10000 Pa), and an oxygen-free gas (specifically, acetylene gas (specifically, acetylene gas) is supplied from the gas supply port 32B to the chamber 32A. C ₂ H ₂ )), the substrate 1 for CNT growth is heated. In the heating process S1 in the present embodiment, the temperature of the CNT growth substrate 1 is raised at a temperature increase rate of 200 to 700 ° C /min.

As described above, the cerium oxide layer of the vermiculite layer 3 in the present embodiment has higher stretchability than cerium oxide. Therefore, even if the CNT growth substrate 1 is heated at a high temperature increase rate of 200 to 700 ° C /min, preferably 500 to 700 ° C /min, the vermiculite layer 3 can follow the thermal expansion of the substrate 2 Scale. As a result, it is possible to prevent cracks from being formed on the vermiculite layer 3.

The CNT growth process S2 is a process of growing (manufacturing) CNTs on the surface of the catalyst layer 4 of the CNT growth substrate 1 which is heated to the growth temperature of the CNTs in the heating process S1 and output to the reaction chamber 33. As shown in Fig. 5, the reaction chamber 33 is provided with three chambers 33A and a gas supply port 33B for supplying gas to each of the chambers 33A.

The inside of the chamber 33A uses the heater 36 to maintain the growth temperature of the CNTs. In the CNT growth process S2, CNTs are produced by a chemical vapor deposition (CVD: Chemical Vapor Deposition) method. Specifically, the inside of the chamber 33A is maintained at a predetermined degree of vacuum (a few Pa to 10000 Pa), and a raw material gas for forming CNTs (for example, acetylene, methane, butane, etc.) is supplied from the gas supply port 33B to the chamber 33A. ). Thereby, CNTs are formed starting from the catalyst fine particles on the surface of the catalyst layer 4.

The post-treatment process S3 is a process for performing the cooling of the CNT growth substrate 1 in which the CNTs are formed in the CNT growth process S2 and the inspection of the formed CNTs in the post-processing chamber 34. When the post-treatment process S3 is completed, the CNT growth substrate 1 is transported to the substrate winding chamber 35, and a protective film is attached to the upper surface thereof, and is wound around the substrate winding device 35A provided in the substrate winding chamber 35. That is, the CNT-forming CNT growth substrate 1 is recovered as a product.

As described above, the CNT growth substrate 1 of the present embodiment includes the base material 2, the vermiculite layer 3, the catalyst layer 4, and the backing layer 5, and the vermiculite layer 3 has an oxygen content ratio of cerium oxide (SiO ₂ ). Less yttrium oxide (SiO _x ) is formed (in other words, yttrium oxide in the vermiculite layer 3 is expressed by the structural formula SiO _x , and the value of x is less than 2). Thereby, even if heating is performed at the rapid temperature increase rate in the heating process S1, the vermiculite layer 3 can expand and contract following the thermal expansion of the base material 2. As a result, CNTs can be favorably grown in the CNT growth process S2 without forming cracks.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining the respective embodiments disclosed in the different embodiments are also included in the present invention. Within the technical scope.

Example

<First Embodiment>

Embodiments of the invention are described below. In the first embodiment, the first to fifth embodiments of the substrate for CNT growth of the present invention and the comparative example 1 as a comparative example of the substrate for CNT growth of the present invention will be described.

The CNT growth substrate of Example 1 was produced as follows. First, 40 g of polyethyl phthalate (ethyl decanoate 45, manufactured by Tama Chemical Co., average molecular weight of 1000) and 60 g of methyltriethoxy decane (produced by Tama Chemical Industry, average molecular weight of 178) were prepared. The solution. Next, 131.4 g of ethanol was mixed in the solution. Next, 113.6 g of water and hydrochloric acid as a catalyst for promoting the hydrolysis reaction of vermiculite were added in a small amount to the solution. After the addition, the mixture was stirred for about one day to prepare a precursor solution of vermiculite.

Next, the precursor solution was applied by roll coating on both sides of a stainless steel film (substrate 2 of the present invention) having a width of 400 mm and a thickness of 50 μm, and dried at 300 ° C for about 10 minutes. Next, by firing at 600 ° C for about 15 minutes, a vermiculite film (the vermiculite layer 3 and the backing layer 5 of the present invention) having a film thickness of 400 nm was formed on both surfaces of the stainless steel film. Next, a film of 5 nm Fe (catalyst layer 4 of the present invention) was formed on one surface of the vermiculite film by the EB method, and a substrate for CNT growth was produced.

Regarding the substrate for CNT growth of Example 2, in addition to the preparation of the precursor solution of vermiculite, 35 g of polyethyl phthalate (ethyl decanoate 45, manufactured by Tama Chemical Co., Ltd., average molecular weight of 1,000), 65 g was used. A methyl triethoxy decane (produced by Tama Chemical Co., Ltd., having an average molecular weight of 178), 216.6 g of ethanol, and 28.4 g of water were produced in the same manner as in the production method of the CNT growth substrate of Example 1.

Regarding the substrate for CNT growth of Example 3, 30 g of polyethyl phthalate (ethyl decanoate 45, produced by Tama Chemical Co., average molecular weight of 1,000), 70 g was used in the preparation of the precursor solution of vermiculite. A methyl triethoxy decane (produced by Tama Chemical Co., Ltd., having an average molecular weight of 178), 234.4 g of ethanol, and 10.7 g of water were produced in the same manner as in the production method of the CNT growth substrate of Example 1.

Regarding the substrate for CNT growth of Example 4, 30 g of polyethyl phthalate (ethyl decanoate 45, manufactured by Tama Chemical Co., average molecular weight of 1,000), 70 g was used in the preparation of the precursor solution of vermiculite. A methyl triethoxy decane (produced by Tama Chemical Co., Ltd., having an average molecular weight of 178), 239.3 g of ethanol, and 5.7 g of water were produced in the same manner as in the production method of the CNT growth substrate of Example 1.

Regarding the substrate for CNT growth of Example 5, except for the preparation of the precursor solution of vermiculite, 10 g of polyethyl phthalate (ethyl decanoate 45, manufactured by Tama Chemical Co., Ltd., average molecular weight of 1,000), 90 g was used. A methyl triethoxy decane (produced by Tama Chemical Co., Ltd., having an average molecular weight of 178), 241.4 g of ethanol, and 3.6 g of water were produced in the same manner as in the production method of the CNT growth substrate of Example 1.

In the substrate for CNT growth of Comparative Example 1, except for the preparation of the precursor solution of vermiculite, 100 g of polyethyl phthalate (ethyl decanoate 45, manufactured by Tama Chemical Co., average molecular weight of 1,000) and 131.4 g were used. In the same manner as in the production method of the CNT growth substrate of Example 1, except that ethanol and 113.6 g of water were used.

Fig. 6 is a graph showing the measurement results of the bond energy of the Si 2p orbital of the vermiculite film in the CNT growth substrates of Examples 1 to 5. Fig. 7 is a graph showing the measurement results of the bond energy of the Si 2p orbital of the vermiculite film in the CNT growth substrate of Comparative Example 1. As shown in Fig. 7, in the vermiculite film in the CNT growth substrate of Comparative Example 1, the peak position of the bond energy of Si is substantially the position of SiO ₂ . That is, the vermiculite film of the CNT growth substrate of Comparative Example 1 was composed of SiO ₂ . On the other hand, in the vermiculite film in the CNT growth substrates of Examples 1 to 5, as shown in Fig. 6, the peak position of the bond energy of Si was lower than the position of SiO ₂ . In other words, the vermiculite film in the CNT growth substrate of Examples 1 to 5 is composed of cerium oxide having at least a part of Si which is not SiO ₂ but has a smaller oxidation degree than SiO ₂ .

The value of _x in the structural formula SiO _x of the vermiculite film of the CNT growth substrates of Examples 1 to 5 was calculated from the measurement results of XPS shown in Fig. 6 . As a result, the values (peak values) of _x in the structural formula SiO _x of the vermiculite film of the CNT growth substrates of Examples 1 to 5 were 1.7, 1.4, 0.9, 0.5, and 0.2, respectively. In other words, in the measurement result of XPS, the value (peak value) of _x in the structural formula SiO _x of the vermiculite film of the CNT growth substrate is less than 2.

Next, the results of a heating experiment in which the substrates for CNT growth of Examples 1 to 5 and Comparative Example 1 were heated at a high temperature increase rate will be described. In the heating experiment, the substrate for CNT growth was heated to 700 ° C at a temperature increase rate of 300 to 700 ° C /min, and it was confirmed whether or not cracks occurred in the vermiculite film of the substrate for CNT growth. Table 1 shows the experimental results. Here, "○" in the table shown in Table 1 indicates that no crack is generated in the vermiculite film, and "△" indicates that cracks have occurred to the extent that the CNTs are well grown, and "╳" indicates generation. A crack that does not allow the CNT to grow well.

Table I

As shown in Table 1, in the vermiculite film of the CNT growth substrate of Comparative Example 1, when heated at a temperature increase rate of 600 ° C /min or 700 ° C /min, cracks in which CNTs could not be favorably grown were generated. . On the other hand, in the vermiculite film of the CNT growth substrate of Examples 1 to 5, even when heated at a temperature increase rate of 700 ° C /min, only the degree of CNT growth was not problematic. Crack. This is because the vermiculite film in the CNT growth substrates of Examples 1 to 5 is composed of cerium oxide having at least a part of Si having a smaller degree of oxidation than SiO ₂ , and thus the vermiculite film can expand and contract following the thermal expansion of the stainless steel film. In particular, in the vermiculite film of the CNT growth substrate of Examples 2 to 5, since the yttrium oxide has high stretchability, even when heated at a temperature increase rate of 700 ° C /min, cracks are not generated at all.

Fig. 8 is a view showing the surface condition after the heating test of the CNT growth substrate of Comparative Example 1. Fig. 9 is a view showing the surface condition after the heating test of the CNT growth substrate of Example 2. In the CNT growth substrate of Comparative Example 1, as shown in Fig. 8, cracks were formed on the surface after the heating test. On the other hand, in the CNT growth substrate of Example 2, as shown in Fig. 9, no crack occurred even after the heating test.

<Second embodiment>

In the second embodiment, an example in which the film thickness of the vermiculite film (the vermiculite layer 3 and the backing layer 5 of the present invention) is changed will be described. The CNT growth substrate in the second embodiment was produced in the same manner as the CNT growth substrate of Example 3 in the first example, except that the film thickness of the vermiculite film was changed. That is, in the CNT growth substrate in the second embodiment, _x in the cerium oxide SiO _x constituting the vermiculite film was 0.9. Further, in the second embodiment, the film thickness of the vermiculite film is varied from 50 nm to 2500 nm by changing the amount of the precursor solution for coating the stainless steel film with the vermiculite film.

In the second embodiment, CNTs were produced using the produced CNT growth substrate, and the orientation length, bulk density of the CNTs, and the presence or absence of cracks in the CNT growth substrate were evaluated. Regarding the orientation length of the CNT, three laser scans were performed in the width direction of the CNT growth substrate, and the average value of the three measurement values was evaluated. The bulk density of the CNTs was measured by peeling off the produced CNTs using an adhesive tape, and then measuring the weight of the peeled CNTs.

The production flow of the CNT in the second embodiment is as follows. First, the CNT growth substrate was heated to 680 ° C at a temperature increase rate of 600 ° C / min while supplying nitrogen gas into the chamber. Next, CNTs were grown (produced) while supplying acetylene gas to the chamber while maintaining the temperature at 680 °C.

Table 2 is a table showing the experimental results of the second embodiment. As shown in Table 2, in the substrate for CNT growth in which the film thickness of the vermiculite film was 50 to 1500 nm, no crack occurred in the vermiculite film. On the other hand, in the substrate for CNT growth in which the thickness of the vermiculite film is 2,000 to 2,500 nm, cracks are generated in the vermiculite film. It is considered that the occurrence of the crack is not caused by a high temperature increase rate, but is caused by the fact that the ruthenium film is excessively thick, and when the CNT growth substrate is made high temperature, the vermiculite film is peeled off from the stainless steel film.

Table II

Further, in the CNT growth substrate in which the talc film has a thickness of 50 to 100 nm, no crack is generated in the vermiculite film, but the orientation length and bulk density of the produced CNT are smaller than those of the other CNT growth substrate. The orientation length and bulk density of CNTs are low, which is not preferable as a product. This is considered to be because the film thickness of the vermiculite film is too small, so that a component such as Cr diffuses from the stainless steel film to the film of Fe as a catalyst layer, and Fe as a catalyst cannot be atomized.

1‧‧‧Carbon nanotube growth substrate

2‧‧‧Substrate

3‧‧‧ ochre layer (middle layer)

4‧‧‧ catalyst layer

5‧‧‧ lining layer

S1, S2, S3‧‧‧ steps

30‧‧‧Carbon tube manufacturing equipment

31‧‧‧Substrate supply room

31A‧‧‧Substrate unwinding device

32‧‧‧heating room

32A‧‧‧室

32B‧‧‧ gas supply port

33‧‧‧Reaction room

33A‧‧‧室

33B‧‧‧ gas supply port

34‧‧‧Reprocessing room

35‧‧‧Substrate winding room

35A‧‧‧Substrate winding device

36‧‧‧heater

Fig. 1 is a cross-sectional view showing the structure of a carbon nanotube growth substrate according to Embodiment 1 of the present invention.

Fig. 2(a) is a structural view of cerium oxide (SiO ₂ ), and Fig. 2 (b) is a structural view of cerium oxide constituting the vermiculite layer of the carbon nanotube growth substrate.

Fig. 3 is a graph showing the measurement results of the bond energy of the Si 2p orbital of the conventional vermiculite layer based on XPS, and the measurement results of the bond energy of the Si 2p orbit of the vermiculite layer in the first embodiment based on XPS.

Fig. 4 is a flowchart showing an example of processing of the method for producing a carbon nanotube according to the first embodiment.

Fig. 5 is a schematic view showing a carbon nanotube manufacturing apparatus of the first embodiment.

Fig. 6 is a graph showing the measurement results of the bond energy of the Si 2p orbital of the vermiculite film on the carbon nanotube growth substrate of the embodiment of the present invention.

Fig. 7 is a graph showing the measurement results of the bond energy of the Si 2p orbital of the vermiculite film on the carbon nanotube growth substrate as a comparative example of the present invention.

Fig. 8 is a view showing the surface condition after the heating test of the carbon nanotube growth substrate as the comparative example.

Fig. 9 is a view showing the surface condition after the heating test of the carbon nanotube growth substrate of the above embodiment.

Fig. 10 is an enlarged view showing the surface state of a conventional carbon nanotube growth substrate.

Claims (5)

A substrate for carbon nanotube growth, comprising: a substrate made of a metal; an intermediate layer formed on a surface of the substrate, comprising ruthenium oxide; and a catalyst layer formed on the intermediate layer The substrate side is the surface on the opposite side, wherein the cerium oxide in the intermediate layer is expressed by the structural formula SiOx, and the value of x is less than 2. The substrate for carbon nanotube growth according to claim 1, wherein when the cerium oxide in the intermediate layer is expressed by the structural formula SiOx, the value of x is 0.2 or more and 1.4 or less. The substrate for carbon nanotube growth according to claim 1 or 2, wherein a backing layer is formed on a surface of the substrate opposite to a surface on which the intermediate layer is formed, the backing layer A cerium oxide containing the same composition as cerium oxide contained in the intermediate layer. The carbon nanotube growth substrate according to the first aspect of the invention, wherein the intermediate layer has a film thickness of 150 nm or more and 1500 nm or less. A carbon nanotube tube manufacturing method using the carbon nanotube growth substrate according to any one of claims 1 to 4, wherein the manufacturing method comprises: a heating process of 700 ° C / min or less Heating the substrate for heating the carbon nanotube tube to the growth temperature of the carbon nanotube tube; and a growth process for supplying the substrate for growing the carbon nanotube to the growth temperature of the carbon nanotube after the heating process The raw material gas is grown on the carbon nanotube growth substrate.