JP2019116398A - Method for producing carbon nanotube-containing composition - Google Patents

Abstract

To provide a method for producing a carbon nanotube-containing composition with high conductivity and high heat resistance.SOLUTION: A method for producing a composition is provided in which a carbon nanotube-containing composition including a two-layer carbon nanotube is allowed to undergo a liquid-phase oxidization treatment and a vacuum heat drying at 90°C or higher and lower than 200°C to give the composition, with a peak temperature in DTG curve of the composition being 790°C or higher and lower than 1000°C.SELECTED DRAWING: None

Description

  The present invention relates to a method of producing a double-walled carbon nanotube-containing composition.

  Carbon nanotube is a material that has attracted attention from many fields because it has many characteristics such as excellent physical properties such as electrical conductivity, thermal conductivity, mechanical strength, and light weight compared to metals. .

  Carbon nanotubes generally have a high graphite structure when the number of layers is small. Single-walled carbon nanotubes and double-walled carbon nanotubes are known to have high characteristics such as conductivity and thermal conductivity because they have a high graphite structure. Further, among multi-walled carbon nanotubes, 2 to 5 carbon nanotubes having a relatively small number of layers have the characteristics of both single-walled carbon nanotubes and multi-walled carbon nanotubes, and thus are noted as promising materials in various applications Are collecting

  Examples of applications utilizing the conductivity of carbon nanotubes include members for clean rooms, members for displays, members for automobiles, and the like. Carbon nanotubes are used to impart antistatic properties, conductivity, electromagnetic wave absorption, electromagnetic wave shielding properties, near infrared cut properties, thermal conductivity, etc. to these members. A carbon nanotube has a high aspect ratio and can form a conductive path with a small amount, so it can be a conductive material and a heat conductive material that are superior in light transmittance and dropout resistance as compared with conventional conductive fine particles such as carbon black.

  In addition, multi-walled carbon nanotubes are often used as electrode materials for batteries (Patent Document 1), and single-walled carbon nanotubes have been studied for light wire applications (Patent Document 2).

  In order to utilize the characteristics of carbon nanotubes in these applications, generally, the higher the quality (crystallinity and purity) of carbon nanotubes, the better. The higher the crystallinity, the higher the conductivity and thermal conductivity that are characteristic of carbon nanotubes. In addition, high heat resistance is also required for carbon nanotubes in applications that require complexation with carbon nanotubes at high temperatures.

  Generally, in most cases, the carbon nanotube-containing composition contains a carbon impurity such as amorphous carbon and a catalyst metal. These impurities are factors that inhibit the conductivity and thermal conductivity, and may also be a cause of a reduction in strength when carbon nanotubes and other materials are combined.

  As a method of removing impurities that cause deterioration of material properties using a carbon nanotube-containing composition, removal of carbon impurities by gas phase oxidation (Patent Document 3) or liquid phase oxidation (Patent Documents 1 and 2) Methods of removing carbon impurities and catalytic metals are known.

  Generally, regardless of the liquid phase or the gas phase, carbon nanotubes are more easily oxidized as the diameter is smaller, and more easily as the number of layers is smaller. Therefore, single-walled carbon nanotubes are more susceptible to defects due to oxidation treatment than double-walled, multi-walled carbon nanotubes, and the characteristics of carbon nanotubes are degraded by oxidation treatment for removing impurities. If oxidation treatment is performed to such an extent that defects do not occur, removal of impurities is not sufficient, and the characteristics of the carbon nanotube-containing composition can not be fully utilized.

  On the other hand, multi-walled carbon nanotubes have high durability to oxidation treatment, but multi-walled carbon nanotubes have the problem that their properties such as conductivity and heat traditionality are lower than single-walled and double-walled carbon nanotubes.

  In order to solve these problems, a method for producing a carbon nanotube-containing composition is also devised by the oxidation treatment of double-walled carbon nanotubes having conductivity comparable to single-walled carbon nanotubes and high resistance to oxidation like multi-walled carbon nanotubes (Patent Document 4) In the relevant literature, a two-walled carbon nanotube-containing composition having very high conductivity is exemplified by liquid phase oxidation treatment.

International Publication No. 2013/161317 Japanese Patent Publication No. 2007-161317 JP 2008-230947 A International Publication No. 2009/069344

  As a method of sufficiently extracting the properties such as conductivity of carbon nanotubes, a method of producing a carbon nanotube-containing composition by liquid phase oxidation of double-walled carbon nanotubes has been proposed, but the heat resistance is still higher in multi-walled carbon nanotubes .

  This invention is made in view of the said subject, Comprising: The objective provides the manufacturing method of a carbon nanotube containing composition with high electroconductivity and high heat resistance, and, thereby, the heat resistance of a carbon nanotube The purpose of the present invention is to provide a carbon nanotube which can be complexed to a resin or metal under high temperature.

MEANS TO SOLVE THE PROBLEM The present inventors came to the following invention, as a result of earnestly examining in order to solve the said subject.
[1] The carbon nanotube-containing composition including the double-walled carbon nanotube is vacuum heat-dried in the range of 90 ° C. or more to less than 200 ° C. after liquid phase oxidation treatment, and the peak temperature of the DTG curve is 790 ° C. or more and 1000 ° C. The manufacturing method of the carbon nanotube containing composition which becomes less than.
[2] The method for producing a carbon nanotube-containing composition according to the above invention, characterized in that the ratio of double-walled carbon nanotubes in the carbon nanotube-containing composition before liquid phase oxidation treatment is 50% or more [3] liquid phase oxidation treatment The method for producing a carbon nanotube-containing composition according to the above invention, characterized in that the ratio of double-walled carbon nanotubes in the subsequent carbon nanotube-containing composition is 50% or more [4] The liquid phase of the liquid phase oxidation treatment is nitric acid The method for producing a carbon nanotube-containing composition according to the above invention [5] The method for producing a carbon nanotube-containing composition according to the above invention, characterized in that the vacuum degree of vacuum drying is less than 760 mmHg and 0.00001 mmHg or more.

According to the method for producing a carbon nanotube-containing composition according to the present invention, it is possible to produce a carbon nanotube-containing composition with high efficiency and simply, very high heat resistance and high conductivity.

FIG. 1 is a schematic view showing the configuration of a synthesis apparatus for synthesizing a carbon nanotube-containing composition used in Examples of the present invention. It is a figure which shows the result of the thermogravimetric analysis of the carbon nanotube containing composition obtained by Example 1, 2 and the comparative example 1. FIG.

  Hereinafter, modes for carrying out the present invention will be described in detail. Note that the present invention is not limited by the following embodiments.

  In the present invention, by carrying out vacuum heating and drying after liquid phase oxidation treatment, a carbon nanotube-containing composition having a very high heat resistance which can not be obtained by ordinary purification can be obtained, and further, carbon nanotube containing high conductivity. It is a feature that it is a composition.

  For that purpose, the peak temperature of the DTG curve is 790 ° C. or more and 1000 by vacuum heating and drying the carbon nanotube-containing composition containing double-walled carbon nanotubes in the range of 90 ° C. or more and less than 200 ° C. after liquid phase oxidation treatment. It is necessary that the carbon nanotube-containing composition having a temperature of less than 0 ° C. be obtained by the production method.

  The peak temperature of the DTG curve referred to here is 790 ° C. or more and less than 1000 ° C. when the temperature is measured at a temperature rising rate of 10 ° C./minute in an air atmosphere, the differential curve (DTG curve) in the TG curve of thermogravimetric analysis The peak temperature at which the strength is greatest is in the range of 790 ° C. or more and less than 1000 ° C. As a measuring apparatus which can perform such a measurement, Shimadzu Corp. make DTG-60, DTG-60H, a Rigaku Co., Ltd. Thermo plus EVO2 TG-DTA series etc. can be used, for example.

  In the present invention, the carbon nanotube-containing composition prior to the liquid phase oxidation treatment needs to contain double-walled carbon nanotubes. Single-walled carbon nanotubes have lower resistance to acid than multi-walled carbon nanotubes, so when removing impurities, they are subject to oxidation defects, and conductivity, thermal conductivity, and strength tend to decrease, and oxidation treatment is performed while maintaining high crystallinity. In general, multi-walled carbon nanotubes have properties such as electrical conductivity and thermal conductivity that are one to two orders of magnitude lower than carbon nanotubes of other layers, and even if purified, single-walled carbon nanotubes Conductivity and thermal conductivity do not become as high as double-walled carbon nanotubes. Therefore, the presence of multi-walled carbon nanotubes in the single-walled or double-walled carbon nanotube-containing composition may cause a decrease in conductivity and thermal conductivity, so the smaller the number of multi-walled carbon nanotubes, the better.

  In the present invention, the indication of the content of multi-walled carbon nanotubes before liquid-phase oxidation treatment varies depending on the number of layers, but among multi-walled carbon nanotubes, single-walled or double-walled carbon nanotubes if it is about 3 to 10 carbon nanotubes. Although the conductivity and thermal conductivity are inferior to those of the above, the ratio of carbon nanotubes of about 3 to 10 is approximately 20 because the conductivity and thermal conductivity are relatively high compared to multi-walled carbon nanotubes having more than 10 layers. % Or less is preferable, 10% or less is more preferable, 5% or less is more preferable, and none is most preferable. The number of multi-walled carbon nanotubes having more than 10 layers is usually 10% or less, preferably 5% or less, and most preferably 0% or less, because the conductivity and thermal conductivity are low.

  The ratio of the number of layers as referred to herein is the ratio of the proportion of the total number of carbon nanotubes contained in the carbon nanotube-containing composition. For example, the carbon nanotube-containing composition is Of all the number of carbon nanotubes that can be counted when observed, it is a ratio that means how many carbon nanotubes with different number of layers occupy. For example, to evaluate the number of layers for 100 carbon nanotubes arbitrarily extracted from a view where carbon nanotubes are 10% or more of the field of view in a 75 nm square field of observation at 400,000 times with a transmission electron microscope Can. When 100 lines of measurement can not be made in one field of view, measurement is made from a plurality of fields of view up to 100 lines. At this time, if one carbon nanotube is partially visible in the field of view, it is counted as one and it is not necessary to necessarily see both ends. In addition, even if it is recognized as two in the field of view, it is possible that they are connected outside the field of view and become one, but in that case, it is counted as two.

  In the present invention, the carbon nanotube-containing composition before liquid phase oxidation treatment when measured by the above method needs to contain double-walled carbon nanotubes, and the ratio is preferably as high as 50% or more. Preferably, it is included. More preferably, 60% or more is contained, and 70% or more is more preferable. Further, it is most preferable that 80% or more of double-walled carbon nanotubes be contained, and it is preferable that 90% or more be contained at the top.

  As described above, the double-walled carbon nanotube has higher conductivity than the multi-walled carbon nanotube, and has high oxidation durability as compared to the single-walled carbon nanotube. Therefore, the ratio of double-walled carbon nanotubes before liquid phase oxidation treatment is preferably as large as possible.

  The proportion of single-walled carbon nanotubes in the carbon nanotube-containing composition before liquid phase oxidation treatment is preferably as low as possible, and preferably less than 50%. More preferably, it is less than 40%, and more preferably less than 30%. Also, it is most preferable that less than 20% of single-walled carbon nanotubes be contained, and most preferably less than 10%. Since single-walled carbon nanotubes have lower resistance to oxidation than double-walled carbon nanotubes, in general, even if the oxidation treatment conditions are adjusted, defects occur in the carbon nanotube graphite layer, and as a result, the conductivity is improved. Since the properties such as durability and heat resistance are lowered, it is very difficult to adjust the oxidation treatment conditions so as not to deteriorate the properties.

  As an index of whether defects occur in the graphite layer, the height ratio (G / D ratio) of G band to D band by Raman spectroscopy is used as a standard, and the higher the G / D ratio, the higher the carbon component of high crystallinity It can be interpreted that there are many. Generally, a carbon nanotube-containing composition having high crystallinity and high purity often has a G / D ratio of 50 or more, and in the case of higher crystallinity and high purity, the G / D ratio is 80 or more, the highest in crystallinity. When the purity is also high, the G / D ratio is 100 or more.

  In general, the carbon nanotube-containing composition can be used for applications requiring higher properties as the number of defective carbon nanotubes is smaller. Therefore, the smaller the number of single-walled carbon nanotubes that are prone to defects due to the treatment of the oxidizing liquid, the better. Originally, it is better that the number of multi-walled carbon nanotubes inferior in properties such as conductivity and thermal conductivity is also small.

  In the carbon nanotube-containing composition after liquid phase oxidation treatment, the ratio of double-walled carbon nanotubes which hardly generate defects is preferably as large as possible depending on adjustment of oxidation treatment conditions, and the ratio is preferably 50% or more. More preferably, it is contained 60% or more, more preferably 70% or more. Further, it is most preferable that 80% or more of double-walled carbon nanotubes be contained, and it is preferable that 90% or more be contained at the top.

  In the single-walled carbon nanotube after liquid phase oxidation treatment, in many cases defects are caused in the graphite layer, so the smaller one is preferable, and less than 50% is preferable. More preferably, it is less than 40%, and more preferably less than 30%. Also, it is most preferable that less than 20% of single-walled carbon nanotubes be contained, and most preferably less than 10%.

  Also for multi-walled carbon nanotubes with poor conductivity and thermal conductivity, it is preferably 20% or less, more preferably 10% or less, and still more preferably 5% if it is a carbon nanotube of about 3 to 10 layers. It is most preferable that the following be absent. The number of multi-walled carbon nanotubes having more than 10 layers is usually 10% or less, preferably 5% or less, and most preferably 0% or less, because the conductivity and thermal conductivity are lower than the others.

  The present invention is characterized in that carbon nanotubes with very high heat resistance can be obtained by vacuum heating and drying after liquid phase oxidation treatment, but the cause is not clear. Although it is an auxiliary factor, removal of amorphous carbon (carbon impurities) by liquid phase oxidation treatment and removal of the catalyst are also considered to be one of the factors for increasing the heat resistance of the carbon nanotube-containing composition. This is because the lower the heat resistance of carbon impurities and the catalyst metal serving as the starting point for breaking the graphite layer at high temperatures, the smaller the content in the carbon nanotube-containing composition, the higher the overall heat resistance.

  Nitric acid is preferable as the oxidizing agent used for the liquid phase oxidation treatment in that it is easy to adjust the condition for treating the carbon nanotube to such an extent that the defect is not excessively generated.

  Generally, as a typical oxidizing agent used for purifying carbon nanotubes by liquid phase oxidation, a mixed solution of nitric acid and sulfuric acid (mixed acid), a mixed solution of sulfuric acid and hydrogen peroxide water (pirania solution), peroxidation Hydrogen water, nitric acid, etc. are used, but among these solutions, except nitric acid, the oxidizing power is strong enough to react with carbon nanotubes at room temperature, and in many cases it is attempted to adjust the reaction rate by cooling Regardless of the number of carbon nanotube layers, most of the carbon nanotubes disappear due to the liquid phase oxidation treatment, or a carbon nanotube-containing composition having a low G / D ratio containing many defects is obtained.

  Nitric acid is not preferable as a solution for liquid phase oxidation treatment because nitric acid does not react with carbon nanotubes at room temperature and can control the reactivity by heating or nitric acid concentration.

  The concentration of nitric acid may be concentrated nitric acid (60 wt% to 70 wt%) as long as the treatment temperature is adjusted, but the concentration is preferably low because it makes it difficult to give defects to carbon nanotubes. Therefore, 50 wt% or less is preferable, more preferably 40 wt% or less, still more preferably 30 wt% or less, most preferably 20 wt% or less, and most preferably 5 wt% or more and 15 wt% or less. It is preferable because the liquid phase oxidation treatment conditions can be easily adjusted.

  If nitric acid is used, the temperature of the liquid phase oxidation treatment is preferably such that when the nitric acid is heated in a reflux state, the superheated state is stabilized, and if the treatment time is adjusted according to the concentration, the carbon nanotube has defects You can end the process before it begins to occur.

  The indication of the completion of the liquid phase oxidation treatment may be taken as the indication of the end of the state in which the catalyst in the carbon nanotube-containing composition is completely dissolved by nitric acid. The confirmation that the catalyst is completely dissolved can be found by filtering and washing the carbon nanotube-containing composition after liquid phase oxidation treatment, and after drying it is confirmed by thermogravimetric analysis that no residue remains. Alternatively, it is also possible to observe the presence or absence of the catalyst by X-ray photoelectron spectroscopy.

  The heating temperature under vacuum heating and drying after the liquid phase oxidation treatment is preferably less than 200 ° C. When it is performed at a very high temperature, carbon impurities slightly remaining and carbon nanotubes or carbon nanotubes react with each other. , And the characteristic of the carbon nanotube may be impaired. Although the reason is not clear, the effect of increasing heat resistance is small by vacuum drying alone, heating is required, and heating at 90 ° C. or higher is preferable. A more preferable heating temperature range is 100 ° C. or more and less than 160 ° C. It is preferable to heat at a temperature higher than the boiling point of water as much as possible. If the temperature is higher than 100 ° C., side reactions are less likely to occur as the temperature is lower.

  As the carbon nanotube used in the present invention, it is most preferable to use a carbon nanotube synthesized by a catalyst floating system. The carbon nanotubes synthesized by the supported catalyst method (for example, fluidized bed method or base method) have a peak temperature of DTG curve even if vacuum heat drying is performed in the range of 90 ° C. or more to less than 200 ° C. after liquid phase oxidation treatment. It is more likely that the carbon nanotube-containing composition does not have a temperature of 790 ° C. or more and less than 1000 ° C. The reasons are various, but it is also one of the reasons that carbon nanotubes synthesized by the supported catalyst method are often single-walled carbon nanotubes or multi-walled carbon nanotubes in many cases. There is also known a method of synthesizing double-walled carbon nanotubes by fluidized bed method, which is a type of supported catalyst method, but since there are more impurities compared to double-walled carbon nanotubes synthesized by gas phase flow method, impurities by liquid phase oxidation Is difficult to remove, and unless prepared under very suitable conditions, the carbon nanotube-containing composition may not have a peak temperature of 790 ° C. or more and less than 1000 ° C. in the DTG curve.

  The reason why carbon nanotubes synthesized by the gas phase flow method are suitably used in the present invention is not clear, but the carbon nanotube-containing composition synthesized by the gas phase flow method has very high crystallinity of carbon nanotubes It is also considered as one of the factors that the carbon nanotube-containing composition has a very small amount of carbon impurities.

  The degree of vacuum at the time of vacuum heating and drying is not particularly limited as long as it is less than atmospheric pressure, but the lower the better. Although the reason is not clear, carbon nanotubes having high heat resistance can not be obtained only by heat drying under atmospheric pressure, which is generally used. If it is less than atmospheric pressure, the effect of the invention is obtained, it is more preferably 380 mmHg or less, more preferably 190 mmHg or less, even more preferably 100 mmHg, and most preferably 50 mmHg Below, it is good that it is 10 mmHg or less at the top. The lower the pressure, the shorter the vacuum heating and drying time can be adjusted, which is preferable because the process can be shortened. The lower limit of decompression is at most 0.00001 mm Hg.

  The vacuum heat-drying time is preferably as long as possible, preferably 6 hours or more, more preferably 8 hours or more, still more preferably 12 hours or more, and most preferably 24 hours or more. The effect of heat resistance can not be imparted any longer, so the effect of high heat resistance can be obtained if performed for at most 72 hours.

  In the present invention, the peak temperature of the highest temperature of the DTG curve of the carbon nanotube-containing composition is 790 ° C. or more and less than 1000 ° C. in thermogravimetric analysis (TG) when the temperature is raised at 10 ° C./min under an air atmosphere. Preferred conditions make it possible to produce a carbon nanotube-containing composition in which the highest peak temperature of the DTG curve is 800 ° C. or more and less than 1000 ° C. Under more suitable conditions, it is 810 ° C. or more but less than 1000 ° C. Under suitable conditions, it is also possible to produce carbon nanotube-containing compositions which have a temperature of 820 ° C. or more and less than 1000 ° C., most preferably 850 ° C. or more and 1000 ° C.

  Further, as one of the features of the present invention, the yield of the heat-resistant carbon nanotube-containing composition obtained by subjecting the synthesized carbon nanotube-containing composition to liquid phase oxidation treatment and vacuum heating and drying is 75% or more The thermogravimetric analysis when the temperature is raised at 10 ° C./min under an air atmosphere with a yield of 80% or more under suitable conditions, and a yield of 90% or more under most suitable conditions It can be mentioned that a carbon nanotube-containing composition in which the highest peak temperature of the DTG curve in (TG) is 790 ° C. or more and less than 1000 ° C. can be obtained.

  Hereinafter, the present embodiment will be described more specifically based on examples. The following examples are provided to facilitate understanding of the present embodiment, and the present embodiment is not limited to these examples. That is, variations, embodiments, and other examples based on the technical idea of the present embodiment are included in the present embodiment.

[Raman spectroscopy]
The powder sample was placed in a resonance Raman spectrometer (INF-300 manufactured by Horiba Jovan Yvon), and measurement was performed using a laser wavelength of 532 nm. At the time of measurement of the G / D ratio, analysis was performed on three different places of the sample, and the arithmetic mean was determined.

[Thermogravimetric analysis]
About 1 mg of a sample was placed in a differential thermal analyzer (DTG-60 manufactured by Shimadzu Corporation), and the temperature was raised from room temperature to 950 ° C. at a heating rate of 10 ° C./minute in air. The peak temperature of weight loss was read from the derivative curve (DTG) of the TGA curve at that time.

[High-resolution transmission electron micrograph]
One mg of the carbon nanotube-containing composition was placed in 1 mL of ethanol, and dispersion treatment was performed using an ultrasonic bath for about 15 minutes. Several drops of the dispersed sample were dropped on the grid and dried. The grid on which the sample was applied in this manner was placed on a transmission electron microscope (JEM-2100, manufactured by JEOL Ltd.) to perform measurement. The measurement magnification was 300,000 times and the acceleration voltage was 120 kV.

Reference Example of Synthesis of Carbon Nanotube-Containing Composition
A carbon nanotube-containing composition was manufactured using the vertical manufacturing apparatus shown in FIG.

  The synthesis apparatus shown in FIG. 1 includes a vertical reaction tube 22 as a reaction vessel for synthesizing a carbon nanotube-containing composition, and a heating furnace 21 provided on the outer periphery of the vertical reaction tube 22 to heat the inside of the vertical reaction tube 22; Liquid spray nozzle 19 for spouting catalytic carbon source solution in the form of mist into vertical reaction tube 22, carrier gas flow meter 14 for liquid spray, tank 16 for storing carrier gas for liquid spray, carrier gas inlet 18 and carrier 18 The carrier gas flow meter 15 for adjusting the flow rate of gas, the tank 17 for storing the carrier gas, the liquid feed pump 13 for introducing the catalyst carbon source solution into the vertical reaction tube 22, and the synthesized carbon nanotube-containing composition It is comprised by the collection | recovery filter 25 installed in the collection | recovery box 24 to collect | recover. Also, the vertical reaction tubes are connected by flanges 20 and 23 so that no gas leaks from the connection.

  The syringe 11 stores a catalyst carbon source solution 12 in which an aromatic compound in a liquid state at normal temperature and pressure and ferrocene which is an organic transition metal compound and thiophene which is an organic sulfur compound are mixed as a carbon source. The introduction amount can be adjusted by the pump 13.

  Further, the catalyst carbon source solution is introduced into the vertical reaction tube 22 by spraying from the liquid spray nozzle 18, and the vapor phase fluid CVD method is performed in the vertical reaction tube 22 surrounded by the superheating furnace 21. Synthesized a carbon nanotube-containing composition. The obtained carbon nanotube-containing composition was recovered by the filter 25. The carrier gas from which the carbon nanotubes have been removed by the filter 25 is exhausted out of the system from the exhaust port 26.

Example 1
Synthesis of carbon nanotube-containing composition The carbon nanotube-containing composition recovered in the reference example is observed with a transmission electron microscope. The proportion of nanotubes was 5%.

  The carbon nanotube-containing composition was subjected to liquid phase oxidation while being stirred in a 60 wt% nitric acid at a reflux temperature of 121 ° C. for 2 hours to obtain a purified carbon nanotube-containing composition. The weight loss of the carbon nanotube-containing composition obtained by heating and heating the purified carbon nanotube-containing composition under vacuum at 150 ° C. under a reduced pressure of 6.7 E-02 Pa is 100%, and most of the DTG curves The peak temperature on the high temperature side was 880 ° C. The results of thermogravimetric analysis are shown in FIG. Moreover, when the carbon nanotube-containing composition after vacuum heating and drying was observed with a transmission electron microscope, the total number ratio of the carbon nanotube-containing composition was 37% single layer, 55% two layers, and 8% three layers. Also, the Raman G / D ratio was 124.

Example 2
The same operation as in Example 1 was performed except that the temperature of vacuum heating and drying was 120 ° C. The results of thermogravimetric analysis are shown in FIG. The peak temperature on the highest temperature side of the DTG curve was 799 ° C. When the carbon nanotube-containing composition after vacuum heating and drying was observed with a transmission electron microscope, the total number ratio of the carbon nanotube-containing composition was the same as in Example 1. Also, the Raman G / D ratio was 124.

[Example 3]
The same operation as in Example 1 was carried out except that the concentration of nitric acid used for liquid phase oxidation treatment was 15% by weight, and the liquid phase oxidation treatment time was 6 hours at 109 ° C. The peak temperature on the highest temperature side of the DTG curve was 853 ° C. The Raman G / D ratio was 96.

Comparative Example 1
The same operation as in Example 1 was performed except that heating and drying were not performed by vacuum heating and drying at 120 ° C. for 15 hours under atmospheric pressure. The results of thermogravimetric analysis are shown in FIG. The peak temperature on the highest temperature side of the DTG curve is 765 ° C., which indicates that the temperature is lower than in the example, and vacuum heat drying is necessary for the production of a carbon nanotube-containing composition having high heat resistance. The Raman G / D ratio was 124.

  According to the method for producing a carbon nanotube-containing composition according to the present invention, it is possible to produce a carbon nanotube-containing composition with high efficiency and simply, high purity, high conductivity, and high heat resistance. .

11 Syringe 12 Catalyst Carbon Source Solution 13 Delivery Pump 14 Carrier Gas Flowmeter for Liquid Spraying 15 Carrier Gas Flowmeter 16, 17 Cylinder 18 Carrier Gas Inlet Port 19 Liquid Spraying Nozzle 20 Flange 21 Heating Furnace 22 Vertical Reaction Tube 23 Flange 24 Collection box 25 Collection filter 26 Exhaust port

Claims (5)

The peak temperature of the DTG curve becomes 790 ° C. or more and less than 1000 ° C. by vacuum heating and drying the carbon nanotube-containing composition including the double-walled carbon nanotube in the range of 90 ° C. or more and less than 200 ° C. after liquid phase oxidation treatment Method for producing a carbon nanotube-containing composition. The method for producing a carbon nanotube-containing composition according to claim 1, wherein the ratio of double-walled carbon nanotubes in the carbon nanotube-containing composition before the liquid phase oxidation treatment is 50% or more. The method for producing a carbon nanotube-containing composition according to claim 1 or 2, wherein the ratio of double-walled carbon nanotubes in the carbon nanotube-containing composition after the liquid phase oxidation treatment is 50% or more. The method for producing a carbon nanotube-containing composition according to any one of claims 1 to 3, wherein the liquid phase of the liquid phase oxidation treatment is nitric acid. The method for producing a carbon nanotube-containing composition according to any one of claims 1 to 4, wherein a vacuum degree of vacuum drying is less than 760 mmHg and equal to or more than 0.00001 mmHg.