JP2020105065A - Method for producing carbon nanotube growth substrate - Google Patents

Abstract

To provide a method for producing a carbon nanotube growth substrate capable of increasing the generation amount of carbon nanotube grown (the length of carbon nanotube, and the bulk density thereof) per unit area, in production of the carbon nanotube through a chemical vapor deposition method using a substrate.SOLUTION: A method includes: a solution-preparing step of preparing a first solution containing a siloxane polymer; and a film-forming step of forming a high-density silica film on a surface of a base material by applying the first solution to the base material and curing the siloxane polymer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method of manufacturing a carbon nanotube growth substrate for manufacturing carbon nanotubes.

As a conventional technique, there is known a technique of manufacturing carbon nanotubes by a chemical vapor deposition (CVD) method using a substrate. The carbon nanotubes produced by the chemical vapor deposition method can produce longer carbon nanotubes than the vapor phase method, but the production amount of the carbon nanotubes per unit area of the substrate is small. Examples of means for solving this problem include (1) increasing the production amount of carbon nanotubes per unit area of the substrate, or (2) using a process capable of continuously producing carbon nanotubes. ..

For example, Patent Documents 1 and 2 disclose carbon nanotube manufacturing techniques by a chemical vapor deposition method. In these techniques, in order to realize a process capable of continuously producing carbon nanotubes, a technique of using a thin roll-shaped stainless foil having an intermediate layer and a catalyst layer formed on the surface as a substrate for growing carbon nanotubes is disclosed. There is.

JP, 2007-70137, A JP, 2013-1598, A

However, in the carbon nanotube growth substrate of the prior art as described above, the intermediate layer is made of aluminum, silicon, or alkali-etched silica, etc., and thus compared with a ceramic base material or a glass (quartz) base material only. However, there is a problem that the amount of carbon nanotubes generated per unit area (length of carbon nanotubes and bulk density of carbon nanotubes) is low.

An object of one aspect of the present invention is to realize a method for manufacturing a carbon nanotube growth substrate capable of increasing the amount of carbon nanotubes produced per unit area.

In order to solve the above problems, a method for manufacturing a substrate for growing carbon nanotubes according to an aspect of the present invention includes a solution preparing step of preparing a first solution containing a siloxane polymer, and applying the first solution to a substrate. And a film forming step of forming a silica film on the surface of the base material by curing the siloxane polymer.

According to one aspect of the present invention, it is possible to manufacture a substrate for growing carbon nanotubes that can increase the amount of carbon nanotubes produced per unit area.

FIG. 3 is a diagram showing the conditions of the polymerization reaction and the data on the reactivity of the polymerization reaction in Example 1. 5 is a diagram showing physical property data of a solution containing a siloxane polymer in Example 2. FIG. FIG. 5 is a diagram showing data of carbon nanotubes produced in Example 2.

A method of manufacturing a substrate for growing carbon nanotubes according to an aspect of the present invention uses a siloxane polymer as a raw material in order to form a high-density silica (SiO ₂ ) film on a base material such as a metal (eg, stainless steel, copper). The method includes a solution preparing step of preparing a first solution containing the same, and a film forming step of forming a silica film on the surface of the base material by applying the first solution to the base material and curing the siloxane polymer.

[Embodiment 1]
Hereinafter, one embodiment of the method for producing a carbon nanotube growth substrate of the present invention will be described in detail. In addition, A to B means that it is larger than A and smaller than B.

The method for manufacturing a substrate for growing carbon nanotubes according to the present embodiment includes a solution preparing step and a film forming step.

(Solution preparation process)
The solution preparation step is a step of preparing a siloxane polymer solution containing a siloxane polymer (hereinafter referred to as a first solution). The solution adjusting step includes the following first step and second step.

In the first step in the solution adjusting step of the first solution used in the present invention, first, a solution containing an alkoxysilane and/or a low condensate of an alkoxysilane (hereinafter referred to as a first raw material) (hereinafter, referred to as a second A solution (hereinafter referred to as a solution) and a solution (hereinafter referred to as a third solution) containing a catalyst (hereinafter, referred to as a first catalyst) that accelerates the polymerization of the first raw material are prepared.

The second solution contains an alkoxysilane and/or a low condensate of alkoxysilane (that is, the first raw material) and a solvent. As the alkoxysilane, tetramethoxysilane, tetraethoxysilane, tetraproxysilane, tetrabutoxysilane or the like can be used. As the low-condensation product of alkoxysilane, a compound in which 2 to 20 alkoxysilanes are linearly condensed (for example, ethyl silicate oligomer) can be used.

The solvent contained in the second solution is not particularly limited as long as it is a solvent capable of dissolving the first raw material, and examples thereof include methanol, ethanol, isopropanol (IPA), n-propanol, n-butanol, Ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and the like can be used.

The third solution contains the first catalyst, water, and a solvent.

The first catalyst is not particularly limited as long as it is a catalyst that accelerates the polymerization of the first raw material, and for example, an acid catalyst such as sulfuric acid, hydrochloric acid, nitric acid, or an organic acid can be used.

The solvent contained in the third solution is not particularly limited as long as it can disperse the first catalyst, and examples thereof include methanol, ethanol, isopropanol (IPA), n-propanol, n-butanol, Ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and the like can be used.

In the first step, the third solution is added to the second solution and hydrolyzed with water in the presence of the first catalyst. Thus, the solution containing the siloxane polymer is prepared by polymerizing the first raw material. In the first step, it is preferable to add the third solution to the second solution so that the amount of the first catalyst with respect to the first raw material is 0.001 to 0.1% by weight.

In the first step, the amount of water in the third solution and/or the third solution with respect to the second solution are added so that 10 to 55 parts by weight of water is added to 100 parts by weight of the first raw material. It is preferable to adjust the addition amount of. When the amount of water added to 100 parts by weight of the first raw material is less than 10 parts by weight, the polymerization reaction of the first raw material is delayed, which is not preferable. Further, if the amount of water added to 100 parts by weight of the first raw material is more than 55 parts by weight, the polymerization reaction of the first raw material will be too fast, and the siloxane polymer produced will gel rapidly, which is not preferable.

Further, in the first step, it is preferable to produce a siloxane polymer having a weight average molecular weight of 1,000 to 30,000, more preferable to produce a siloxane polymer having a weight average molecular weight of 1,000 to 20,000, and a weight average molecular weight of 2,000 to 20,000. It is more preferable to form a siloxane polymer, and it is more preferable to form a siloxane polymer having a weight average molecular weight of 3000 to 12000. As a result, the formed silica film can have a higher density. If the weight average molecular weight is 1000 or less, a coating film that can obtain high-density carbon nanotubes may not be formed, or a uniform coating film may not be obtained. When the weight average molecular weight is 30,000 or more, the siloxane polymer gels in a short period of time (for example, within half a day) and cannot be stored for a long period of time (preferably at room temperature for 1 week, more preferably at least 6 months), which is preferable. Absent.

The weight average molecular weight of the siloxane polymer can be controlled, for example, by controlling at least one of the concentration of the first raw material, the polymerization reaction temperature, the polymerization reaction time, and the amount of water added. For example, when the alkoxysilanes are bound to each other, it is necessary that the alkoxysilanes are located at a distance (area) where the alkoxysilanes can be brought close to each other to react. When the concentration of the first raw material is low, the alkoxysilanes are hard to come close to each other and the reaction rate becomes slow. On the other hand, when the concentration of the first raw material is high, the distance between the alkoxysilanes is short, and the alkoxysilanes can react with each other immediately, so that the reaction rate becomes faster. However, even when the concentration of the first raw material is high, the alkoxysilane reacts with the progress of the reaction to form a siloxane oligomer (siloxane polymer), whereby the concentration of the first raw material decreases and the reactivity gradually decreases. .. For example, when the solid content of the siloxane polymer in the first siloxane polymer solution described in Example 1 below is 10% to 20%, the reaction rate is slow, and when it is 30% to 40%, the reaction rate is slow but slow. The reaction rate tends to increase sharply when the concentration increases to 50% or more.

On the other hand, when the temperature in the reaction solution becomes high, the movement of the reactive monomer becomes active (the reactive monomer becomes easy to move). Therefore, since the kinetic energy of the alkoxysilane increases due to the heat energy, it becomes easy to approach the region where the reaction easily occurs, and the reaction easily proceeds. For example, when the temperature of the reaction of the first siloxane polymer solution is 20° C. or lower, the reaction rate is very slow, when it is 30° C. to 50° C., the reaction rate gradually increases, and when it is 80° C. or higher, the reaction occurs. The speed tends to be quite fast.

Regarding the amount of water added, as will be seen from FIG. 1 which will be described later, hydrolysis (≡Si—OR→≡Si—H) is promoted by water, highly reactive silanol (≡Si—OH) is generated, and silanol is added. Form a siloxane bond (≡Si—O—Si≡). If the amount of water is large, the reaction with water proceeds rapidly, and it becomes easy to polymerize. In addition, the non-hydrolyzed alkoxysilane and the low-condensation product of the alkoxysilane, which are the raw materials, are not compatible with water. Therefore, in order to uniformly hydrolyze, it is preferable to add dropwise over a period of time with stirring.

As described above, for example, by controlling at least one of the concentration of the first raw material, the reaction temperature of the polymerization, the reaction time of the polymerization, and the amount of water added, and adjusting the reaction rate appropriately, the weight average of the siloxane polymer can be increased. The second step can be appropriately performed so that the molecular weight becomes a desired value.

The molecular weight distribution (PDI (=Mw/Mn)) is preferably 1.2 to 6.0, and particularly preferably 4.5 or less. When the molecular weight distribution is 6.0 or more, a large amount of unreacted monomer component remains, and a coating film that can obtain high-density carbon nanotubes cannot be formed at the time of film formation, or the solubility in a solvent and gel decrease with the increase in molecular weight. And the film formation becomes impossible. The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymer are measured by gel permeation chromatography (GPC) by the methods described in Examples below.

The second step in the solution adjusting step of the first solution used in the present invention is a step of preparing the first solution by removing the first catalyst from the solution prepared in the first step. The method of removing the first catalyst in the second step is not particularly limited, but for example, a method of adding an anion exchange resin to the solution prepared in the first step can be used. For example, when the first catalyst is sulfuric acid, the sulfate ion SO ₄ ²⁻ can be removed by the anion exchange resin by adding the anion exchange resin to the solution prepared in the first step.

By removing the first catalyst from the solution prepared in the first step, it is possible to suppress the polymerization of the first raw material (end the reaction of the first step). This can prevent the siloxane polymer from gelling, and a stable first solution can be prepared.

(Film forming process)
Next, the film forming step is a step of applying a siloxane polymer solution (first solution) to the base material and curing the siloxane polymer to form a silica film on the surface of the base material. The solution adjusting step includes the following third to sixth steps. In this embodiment, a thin stainless foil is used as the base material.

The third step is a step of preparing a solution containing a second catalyst that accelerates the curing of the siloxane polymer (hereinafter referred to as a fourth solution).

The second catalyst is preferably a thermal acid generator that generates an acid when heat is applied or a photoacid generator that generates an acid when irradiated with light. Examples of the thermal acid generator include an amine block of p-toluene sulfonic acid, an amine block of dodecylbenzene sulfonic acid, an amine block of alkylnaphthalene sulfonic acid, and an amine block of dialkyl sulfosuccinic acid. Examples of the photoacid generator include sulfonium salts, iodonium salts, dialkylsulfonyldiazomethanes, and the like.

The fourth solution preferably contains a solid content adjusting agent (for example, n-propanol) in order to apply a solution having a desired film thickness in the following fourth step.

The fourth step is a step of applying a mixed liquid of the first solution and the fourth solution to the base material. The coating of the mixed solution can be performed by using a known coating method or printing method, and for example, a spin coater, a gravure coater, a die coater, screen printing, or the like can be used. Further, after the mixed liquid is applied, the mixed liquid may be cured.

The fifth step is a step of forming a silica film by baking the mixed solution of the solution and the fourth solution applied to the base material. Specifically, a silica film is formed by baking at 500 to 800° C. for 5 to 30 minutes.

As described above, the third mixed liquid contains the second catalyst that accelerates the curing of the siloxane polymer, so that a higher density silica film can be formed by firing.

The sixth step is a step of forming a catalyst layer on the silica film. In this embodiment, the catalyst layer is made of iron (Fe) and is formed by the EB (electron beam, electron beam) method or the like. However, the catalyst layer in the present invention is not limited to Fe, and may be made of, for example, cobalt (Co) or nickel (Ni). Moreover, the catalyst layer in the present invention may be formed by a sputtering method, a vacuum deposition method, or the like.

As described above, the method for manufacturing a substrate for growing carbon nanotubes according to the present embodiment includes a solution preparing step of preparing a first solution containing a siloxane polymer, and applying the first solution to a base material to cure the siloxane polymer. And a film forming step of forming a silica film on the surface of the base material. According to the above configuration, since the silica film is formed from the siloxane polymer, the high density silica film can be formed. As a result, the production amount of carbon nanotubes per unit area can be increased.

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

An embodiment of the present invention will be described below.

In this example, an experiment was conducted on the amount of water added to 100 parts by weight of the first raw material in the first step of the solution adjusting step of the first solution. In this example, an alkoxysiloxane oligomer (molecular weight 1282) was used as the first raw material, and the polymerization reaction was performed under the conditions shown in FIG. Note that FIG. 1 also shows data on the reactivity of the polymerization reaction.

As shown in FIG. 1, when 9.7 parts by weight of water was added to 100 parts by weight of the first raw material, the polymerization reaction was very slow. In addition, when more than 56.6 parts by weight of water was added to 100 parts by weight of the first raw material, the polymerization reaction was very fast and the siloxane polymer formed during the second step was Gelation progressed. In particular, when 119.3 parts by weight of water was added to 100 parts by weight of the first raw material, the polymerization reaction was very fast and gelation occurred immediately. Therefore, it is preferable to add 10.00 parts by weight to 55.00 parts by weight of water to 100 parts by weight of the first raw material, and to add 14.05 parts by weight to 49.7 parts by weight of water. Particularly preferred.

Next, carbon nanotubes of the following first to third examples were produced using the method for producing a carbon nanotube growth substrate of the present invention.

<First Example: Polymerization of siloxane polymer 1>
In the first example, first, a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer was charged with ethyl silicate oligomer (product name: silicate 45, manufactured by Tama Chemical Industry Co., Ltd.) and n-propanol as a solvent by weight. The mixture was put in a ratio of 100:130. Next, with stirring the solution at 25° C., 0.25 part by weight of 6N-sulfuric acid (first catalyst), 19.4 parts by weight of ion-exchanged water, and 9.100 parts by weight of the ethyl silicate oligomer. 4 parts by weight of n-propanol was added dropwise over 1 hour and then stirred for 24 hours to prepare a siloxane polymer solution.

Next, in order to remove sulfuric acid (first catalyst), 13.0 parts by weight of anion exchange resin (trade name; WA20, Mitsubishi Chemical) was added to 100 parts by weight of the ethyl silicate oligomer in the obtained siloxane polymer solution. After adding the product), the mixture was stirred for 5 to 10 minutes, and it was confirmed that the pH was 5 to 6 using pH test paper. Then, the anion exchange resin was filtered off to obtain a colorless and transparent siloxane polymer. The anion exchange resin was treated with a 1N-NaOH solution prior to use, washed with water, and then replaced with n-propanol.

The obtained siloxane polymer was diluted with a DMF solution (10 mM LiBr) in which lithium bromide was dissolved and measured by GPC (gel permeation chromatography) using the DMF solution as an eluent. As a result, the weight average molecular weight of the siloxane polymer was 2635. Physical property data of the obtained solution containing a siloxane polymer (referred to as a first siloxane polymer solution) are shown in FIG. In addition, in FIG. 2, the yield is a value obtained by dividing the obtained siloxane polymer solution by the weight of the raw material such as ethyl silicate oligomer. When this yield is low, adsorption of the polymer component due to ion exchange resin treatment or the like, or volatilization of the solvent is considered, and there is a possibility that an unfavorable reaction proceeds in the obtained siloxane polymer solution. Therefore, the yield is preferably 90% or more.

Next, a solid content of the obtained siloxane polymer was prepared with n-propanol, and a spin coater was used to apply a film onto a stainless steel foil so that the film thickness after curing was about 450 nm. Curing treatment was performed for 5 minutes. Film formation and curing were similarly performed on the surface opposite to the stainless steel foil.

Next, the stainless steel foil was baked at 700° C. for 15 minutes to prepare a carbon nanotube growth substrate on which a silica film was formed. No cracks were generated in the silica film on the obtained carbon nanotube growth substrate. Next, Fe having a film thickness of about 3 nm was formed on the silica film by using the EB vapor deposition method.

Next, the carbon nanotubes were generated on the carbon nanotube growth substrate by the chemical vapor deposition method. Specifically, after the carbon nanotube growth substrate was heated to 660° C. while supplying nitrogen gas into the chamber, carbon nanotubes were generated while supplying acetylene gas into the chamber while maintaining the temperature at 660° C. The data of the produced carbon nanotubes are shown in FIG.

<Second Example: Polymerization of siloxane polymer 2>
In the second example, first, a four-necked flask equipped with a stirrer, a dropping funnel, a reflux tube, and a thermometer was used, and an ethyl silicate oligomer (product name: silicate 45, manufactured by Tama Chemical Industry) and n-propanol as a solvent were used. Was added so that the weight ratio was 100:130. Next, with stirring the solution at 25° C., 0.25 part by weight of 6N-sulfuric acid (first catalyst), 19.4 parts by weight of ion-exchanged water, and 9.100 parts by weight of the ethyl silicate oligomer. 4 parts by weight of n-propanol was added dropwise over 1 hour. Then, the temperature in the system was set to 80° C. using an oil bath, and the mixture was refluxed for 8 hours to prepare a siloxane polymer solution.

Next, in order to remove sulfuric acid (first catalyst), 13.0 parts by weight of anion exchange resin (trade name; WA20, Mitsubishi Chemical) was added to 100 parts by weight of the ethyl silicate oligomer in the obtained siloxane polymer solution. It was stirred for 5 to 10 minutes after adding (made by a company), and it was confirmed that the pH was 5 to 6 using pH test paper. Then, the anion exchange resin was filtered off to obtain a colorless and transparent siloxane polymer. The anion exchange resin was treated with a 1N-NaOH solution prior to use, washed with water, and then replaced with n-propanol.

The obtained siloxane polymer was diluted with a DMF solution (10 mM LiBr) in which lithium bromide was dissolved and measured by GPC (gel permeation chromatography) using the DMF solution as an eluent. As a result, the weight average molecular weight of the siloxane polymer was 11470. Physical property data of the obtained solution containing a siloxane polymer (referred to as a second siloxane polymer solution) are shown in FIG.

As for the subsequent steps, the same steps as in the first example were performed. The data of the carbon nanotubes of the second embodiment are shown in FIG. In addition, no crack of the silica film was generated on the obtained carbon nanotube growth substrate.

<Third Example: Polymerization of siloxane polymer 3>
In the third example, first, a four-necked flask equipped with a stirrer, a dropping funnel, a reflux tube, and a thermometer was equipped with an ethyl silicate oligomer (product name: silicate 45, manufactured by Tama Chemical Industry Co., Ltd.) and n-propanol as a solvent. Were added so that the weight ratio was 100:78. Next, while stirring the solution at 25° C., 0.25 parts by weight of 6N-sulfuric acid (first catalyst), 14.1 parts by weight of ion-exchanged water, and 43. 2 parts by weight of n-propanol was added dropwise over 1 hour. Then, the temperature in the system was set to 80° C. using an oil bath, and the mixture was refluxed for 24 hours to prepare a siloxane polymer solution.

Next, to the obtained siloxane polymer solution, 23 parts by weight of n-propanol was added to 100 parts by weight of the ethyl silicate oligomer to adjust the concentration.

Next, in order to remove the sulfuric acid (first catalyst), 13.0 parts by weight of anion exchange resin (trade name; WA20, manufactured by Mitsubishi Chemical Corporation) was added to the siloxane polymer solution based on 100 parts by weight of ethyl silicate oligomer. After adding, the mixture was stirred for 5 to 10 minutes, and it was confirmed that the pH was 5 to 6 using a pH test paper. Then, the anion exchange resin was filtered off to obtain a colorless and transparent siloxane polymer. The anion exchange resin was treated with a 1N-NaOH solution prior to use, washed with water, and then replaced with n-propanol.

The obtained siloxane polymer was diluted with a DMF solution (10 mM LiBr) in which lithium bromide was dissolved and measured by GPC (gel permeation chromatography) using the DMF solution as an eluent. As a result, the weight average molecular weight of the siloxane polymer was 16049. Physical property data of the obtained solution containing a siloxane polymer (referred to as a third siloxane polymer solution) are shown in FIG.

<Fourth Example: Polymerization of siloxane polymer 4>
In the fourth example, first, a four-necked flask equipped with a stirrer, a dropping funnel, a reflux tube, and a thermometer was equipped with an ethyl silicate oligomer (product name: silicate 45, manufactured by Tama Chemical Industry Co., Ltd.) and n-propanol as a solvent. Was added so that the weight ratio was 100:75. Next, while stirring the solution at 25° C., 0.25 part by weight of 6N-sulfuric acid (first catalyst), 19.4 parts by weight of ion-exchanged water, and 40. 6 parts by weight of n-propanol was added dropwise over 1 hour. Then, the temperature of the system was set to 40° C. using a water bath, and the mixture was stirred for 55 hours to prepare a siloxane polymer solution.

Next, in order to remove the sulfuric acid (first catalyst), 13.0 parts by weight of an anion exchange resin (trade name: WA20, Mitsubishi Chemical) was added to 100 parts by weight of the ethyl silicate oligomer in the obtained siloxane polymer solution. It was stirred for 5 to 10 minutes after adding (made by a company), and it was confirmed that the pH was 5 to 6 using pH test paper. Then, the anion exchange resin was filtered off to obtain a colorless and transparent siloxane polymer. The anion exchange resin was treated with a 1N-NaOH solution prior to use, washed with water, and then replaced with n-propanol.

The obtained siloxane polymer was diluted with a DMF solution (10 mM LiBr) in which lithium bromide was dissolved and measured by GPC (gel permeation chromatography) using the DMF solution as an eluent. As a result, the weight average molecular weight of the siloxane polymer was 4,441. Physical property data of the obtained solution containing a siloxane polymer (referred to as a fourth siloxane polymer solution) are shown in FIG.

<Fifth Example: Polymerization of siloxane polymer 5>
In the fifth example, first, a four-necked flask equipped with a stirrer, a dropping funnel, a reflux tube, and a thermometer was equipped with an ethyl silicate oligomer (product name: silicate 45, manufactured by Tama Chemical Industry Co., Ltd.) and n-propanol as a solvent. Were added so that the weight ratio was 100:46. Next, while stirring the solution at 25° C., 0.25 part by weight of 6N-sulfuric acid (first catalyst), 19.4 parts by weight of ion-exchanged water, and 25. 0 part by weight of n-propanol was added dropwise over 1 hour. Then, the temperature of the system was set to 40° C. using a water bath, and the mixture was stirred for 55 hours to prepare a siloxane polymer solution.

Next, in order to remove the sulfuric acid (first catalyst), 13.0 parts by weight of an anion exchange resin (trade name: WA20, Mitsubishi Chemical) was added to 100 parts by weight of the ethyl silicate oligomer in the obtained siloxane polymer solution. It was stirred for 5 to 10 minutes after adding (made by a company), and it was confirmed that the pH was 5 to 6 using pH test paper. Then, the anion exchange resin was filtered off to obtain a colorless and transparent siloxane polymer. The anion exchange resin was treated with a 1N-NaOH solution prior to use, washed with water, and then replaced with n-propanol.

The obtained siloxane polymer was diluted with a DMF solution (10 mM LiBr) in which lithium bromide was dissolved and measured by GPC (gel permeation chromatography) using the DMF solution as an eluent. As a result, the weight average molecular weight of the siloxane polymer was 27718. Physical property data of the obtained solution containing a siloxane polymer (referred to as a fifth siloxane polymer solution) are shown in FIG.

<Sixth Example: Siloxane polymer polymerization 6>
In the sixth example, first, a four-necked flask equipped with a stirrer, a dropping funnel, a reflux tube, and a thermometer was charged with ethyl silicate oligomer (product name: silicate 45, manufactured by Tama Chemical Industry Co., Ltd.) and n-propanol as a solvent. Were added so that the weight ratio was 100:131. Next, with stirring the solution at 25° C., 0.25 parts by weight of 6N-sulfuric acid (first catalyst), 19.4 parts by weight of ion-exchanged water, and 94. 0 part by weight of n-propanol was added dropwise over 1 hour. Then, the temperature of the system was set to 60° C. using a water bath, and the mixture was stirred for 65 hours to prepare a siloxane polymer solution.

Next, in order to remove the sulfuric acid (first catalyst), 13.0 parts by weight of an anion exchange resin (trade name: WA20, Mitsubishi Chemical) was added to 100 parts by weight of the ethyl silicate oligomer in the obtained siloxane polymer solution. It was stirred for 5 to 10 minutes after adding (made by a company), and it was confirmed that the pH was 5 to 6 using pH test paper. Then, the anion exchange resin was filtered off to obtain a colorless and transparent siloxane polymer. The anion exchange resin was treated with a 1N-NaOH solution prior to use, washed with water, and then replaced with n-propanol.

The obtained siloxane polymer was diluted with a DMF solution (10 mM LiBr) in which lithium bromide was dissolved and measured by GPC (gel permeation chromatography) using the DMF solution as an eluent. As a result, the weight average molecular weight of the siloxane polymer was 2431. Physical property data of the obtained solution containing a siloxane polymer (referred to as a sixth siloxane polymer solution) are shown in FIG.

<Seventh Example: Polymerization of siloxane polymer 7>
In the seventh example, first, a four-necked flask equipped with a stirrer, a dropping funnel, a reflux tube, and a thermometer was charged with ethyl silicate oligomer (product name: silicate 45, manufactured by Tama Chemical Industry Co., Ltd.) and n-propanol as a solvent. Were added so that the weight ratio was 100:131. Next, with stirring the solution at 25° C., 0.25 parts by weight of 6N-sulfuric acid (first catalyst), 19.4 parts by weight of ion-exchanged water, and 94. 0 part by weight of n-propanol was added dropwise over 1 hour. After that, the temperature of the system was set to 80° C. using a water bath and refluxed for 76 hours to prepare a siloxane polymer solution.

Next, in order to remove the sulfuric acid (first catalyst), 13.0 parts by weight of an anion exchange resin (trade name: WA20, Mitsubishi Chemical) was added to 100 parts by weight of the ethyl silicate oligomer in the obtained siloxane polymer solution. It was stirred for 5 to 10 minutes after adding (made by a company), and it was confirmed that the pH was 5 to 6 using pH test paper. Then, the anion exchange resin was filtered off to obtain a colorless and transparent siloxane polymer. The anion exchange resin was treated with a 1N-NaOH solution prior to use, washed with water, and then replaced with n-propanol.

The obtained siloxane polymer was diluted with a DMF solution (10 mM LiBr) in which lithium bromide was dissolved and measured by GPC (gel permeation chromatography) using the DMF solution as an eluent. As a result, the weight average molecular weight of the siloxane polymer was 3164. Physical property data of the obtained solution containing a siloxane polymer (referred to as a seventh siloxane polymer solution) are shown in FIG. The weight average molecular weight (Mw) of the fifth siloxane polymer solution was as high as 27718, and the siloxane polymer gelled in a shorter period than the siloxane polymers of the other Examples. In the case of other examples, it could be stored in the refrigerator without gelation even after 1 week.

As for the subsequent steps, the same steps as in the first example were performed. The data of the carbon nanotube of the third embodiment is shown in FIG. In addition, no crack of the silica film was generated on the obtained carbon nanotube growth substrate.

<Eighth Example>
In the eighth example, the siloxane polymer produced in the first example (the first siloxane polymer) was added to the amine block of p-toluenesulfonic acid, which is a thermal acid generator, as a curing catalyst (second catalyst) (product name). : NACURE 2500, manufactured by KING INDUSTRIES) was added in an amount of 0.1 wt% with respect to the solid content of the siloxane polymer. Next, a solid content is prepared with n-propanol, and a spin coater is applied to a stainless steel foil so that the film thickness after curing is about 450 nm to form a film, and the film is cured at 200° C. for 5 minutes. It was Film formation and curing were similarly performed on the surface opposite to the stainless steel foil.

Next, the stainless steel foil was baked at 700° C. for 15 minutes to prepare a carbon nanotube growth substrate on which a silica film was formed. No cracks were generated in the silica film on the obtained carbon nanotube growth substrate. Next, Fe having a film thickness of about 3 nm was formed on the silica film by using the EB vapor deposition method.

Next, the carbon nanotubes were generated on the carbon nanotube growth substrate by the chemical vapor deposition method. Specifically, after the carbon nanotube growth substrate was heated to 660° C. while supplying nitrogen gas into the chamber, carbon nanotubes were generated while supplying acetylene gas into the chamber while maintaining the temperature at 660° C. The data of the produced carbon nanotubes are shown in FIG. The bulk density of carbon nanotubes is, for example, the mass per unit area (unit weight: unit mg/cm ² ), the length of carbon nanotubes (scanning electron microscope (SEM, manufactured by JEOL Ltd.), or non-contact film thickness). Total (measured by KEYENCE)) and

As shown in FIG. 3, carbon nanotubes are manufactured using the substrate for growing carbon nanotubes manufactured by the manufacturing method of the present invention, whereby the orientation length of the carbon nanotubes is long and the bulk density of the carbon nanotubes is increased. I was able to do it. That is, the amount of carbon nanotubes produced per unit area was large.

Claims (5)

A method of manufacturing a substrate for growing carbon nanotubes, comprising:
A solution preparing step of preparing a first solution containing a siloxane polymer;
And a film forming step of forming a silica film on a surface of the base material by applying the first solution to the base material and curing the siloxane polymer. Method. The solution preparation step,
To the second solution containing the alkoxysilane and/or the low condensate of the alkoxysilane, a third solution containing the first catalyst that accelerates the polymerization of the alkoxysilane and/or the low condensate of the alkoxysilane is added, and the alkoxysilane is added. And/or a first step of preparing a solution containing a siloxane polymer by polymerizing a low condensate of the alkoxysilane,
The second step of preparing the first solution by removing the first catalyst from the solution prepared in the first step, the substrate for growing carbon nanotubes according to claim 1. Manufacturing method. The method for producing a substrate for growing carbon nanotubes according to claim 1 or 2, wherein the siloxane polymer having a weight average molecular weight of 1,000 to 20,000 is produced in the solution preparing step. The carbon nanotube according to claim 2, wherein in the first step, 14 to 50 parts by weight of water is added to 100 parts by weight of the total of the alkoxysilane and the low condensate of the alkoxysilane. Method for manufacturing growth substrate. The film forming step is
A third step of preparing a fourth solution containing a second catalyst that accelerates the curing of the siloxane polymer,
A fourth step of applying a mixed solution of the first solution and the fourth solution to the base material;
A fifth step of forming the silica film by baking the mixed liquid applied to the base material,
A sixth step of forming a catalyst layer on the silica film, the method for producing a substrate for growing carbon nanotubes according to any one of claims 1 to 4.

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