WO2009157529A1 - Ensemble de nanotubes de carbone et procédé pour leur fabrication - Google Patents

Ensemble de nanotubes de carbone et procédé pour leur fabrication Download PDF

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WO2009157529A1
WO2009157529A1 PCT/JP2009/061675 JP2009061675W WO2009157529A1 WO 2009157529 A1 WO2009157529 A1 WO 2009157529A1 JP 2009061675 W JP2009061675 W JP 2009061675W WO 2009157529 A1 WO2009157529 A1 WO 2009157529A1
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carbon nanotube
carbon nanotubes
aggregate
catalyst
nanotube aggregate
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PCT/JP2009/061675
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Japanese (ja)
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謙一 佐藤
秀和 西野
和義 樋口
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東レ株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/78—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali- or alkaline earth metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon

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  • the present invention relates to an aggregate of carbon nanotubes and a method for producing the same. Further, the present invention relates to a molded body, a composition, and a conductive composite including a carbon nanotube aggregate.
  • Carbon nanotubes have a substantially cylindrical shape formed by winding one surface of graphite.
  • Single-walled carbon nanotubes are referred to as single-walled carbon nanotubes
  • multi-walled carbon nanotubes are referred to as multi-walled carbon nanotubes.
  • carbon nanotubes usually have a high graphite structure when the number of layers is smaller, and single-walled carbon nanotubes have high characteristics such as electrical conductivity and thermal conductivity. Since multi-walled carbon nanotubes have a low degree of graphitization, it is also known that electrical conductivity and thermal conductivity are generally lower than single-walled carbon nanotubes.
  • multi-walled carbon nanotubes are known to have higher durability than single-walled carbon nanotubes because of the large number of graphite layers.
  • double-walled carbon nanotubes are attracting attention as promising materials in various applications because they have the characteristics of both single-walled carbon nanotubes and multi-walled carbon nanotubes.
  • carbon nanotube aggregates having a high proportion of double-walled carbon nanotubes can be synthesized by chemical vapor deposition, plasma method, pulse arc method or the like.
  • Patent Document 1 and Non-Patent Document 1 produce double-walled carbon nanotubes with relatively high quality and high purity by catalytic chemical vapor deposition.
  • the carbon nanotubes of Patent Document 1 have a strong and very large bundle structure, the nano effect of each carbon nanotube cannot be exhibited, and various application developments are difficult. It is guessed. In particular, since it is very difficult to disperse in a resin or a solvent, development in various applications is limited. Further, since the carbon nanotubes of Non-Patent Document 1 are synthesized using a horizontal fixed bed reactor, the contact of the raw material gas with the catalyst is not uniform, and high-quality carbon nanotubes are not obtained.
  • Patent Document 2 discloses a method for synthesizing double-walled carbon nanotubes by bringing methane as a raw material gas into contact with a catalyst at a linear velocity of 9.5 ⁇ 10 ⁇ 3 cm / sec or less. Although a relatively high quality double-walled carbon nanotube is obtained, the Raman G / D ratio is about 20. At present, amorphous carbon is generated, and a very high quality double-walled carbon nanotube aggregate has not been obtained.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a double-walled carbon nanotube aggregate having very high conductivity, high quality, and good dispersibility, and a method for producing the same.
  • the present invention is an aggregate of carbon nanotubes that satisfies all the following conditions (1) to (4).
  • the volume resistivity of the carbon nanotube aggregate is 1 ⁇ 10 ⁇ 4 ⁇ ⁇ cm or more and 1 ⁇ 10 ⁇ 2 ⁇ ⁇ cm or less;
  • 50% or more of the carbon nanotubes in the aggregate of carbon nanotubes are double-walled carbon nanotubes;
  • the Raman G / D ratio of the carbon nanotube aggregate at a measurement wavelength of 532 nm is 30 or more and 200 or less;
  • the combustion peak temperature of the carbon nanotube aggregate is 550 ° C. or higher and 700 ° C. or lower.
  • the present invention is also a method for producing a carbon nanotube aggregate by contacting a raw material gas and a catalyst in a reactor, wherein the raw material gas containing methane at a concentration of 10% by volume or less contains a linear velocity of 4 cm / sec or more, This is a method for producing an aggregate of carbon nanotubes that is circulated at 15 cm / sec or less and is brought into contact with a catalyst at 500 to 1200 ° C.
  • an aggregate of double-walled carbon nanotubes having a low volume resistivity, high quality, and good dispersibility can be obtained.
  • the molded article, composition and conductive composite obtained from the carbon nanotube aggregate of the present invention exhibit good performance.
  • FIG. 1 shows a state in which the catalyst exists uniformly in the cross section of the reaction tube.
  • FIG. 2 is a schematic view of the vertical fluidized bed apparatus used in the examples.
  • FIG. 3 is a high-resolution transmission electron micrograph of the carbon nanotubes obtained in Example 1.
  • 4 is a Raman spectroscopic analysis chart of the carbon nanotubes obtained in Example 1.
  • FIG. 1 shows a state in which the catalyst exists uniformly in the cross section of the reaction tube.
  • FIG. 2 is a schematic view of the vertical fluidized bed apparatus used in the examples.
  • FIG. 3 is a high-resolution transmission electron micrograph of the carbon nanotubes obtained in Example 1.
  • 4 is a Raman spectroscopic analysis chart of the carbon nanotubes obtained in Example 1.
  • the aggregate of carbon nanotubes means an aggregate of a plurality of carbon nanotubes.
  • the existence form of the carbon nanotube is not particularly limited, and the carbon nanotubes may be present independently, in the form of a bundle or entanglement, or in a mixed form thereof. Further, carbon nanotubes having various numbers of layers and diameters may be included. Moreover, even when it is contained in the composition containing another component or in the composite, it is sufficient that a plurality of carbon nanotubes are contained. Further, impurities (for example, a catalyst) derived from the carbon nanotube production method may be included.
  • the aggregate of carbon nanotubes has a volume resistivity of 1 ⁇ 10 ⁇ 4 ⁇ ⁇ cm or more and 1 ⁇ 10 ⁇ 2 ⁇ ⁇ cm or less.
  • This volume resistivity can be calculated by preparing a carbon nanotube film as follows, measuring the surface resistance value of the film by the four-terminal method, and then multiplying the surface resistance value by the film thickness of the carbon nanotube film. .
  • the surface resistance value can be measured by, for example, Loresta EP MCP-T360 (manufactured by Dia Instruments Co., Ltd.) using a four-terminal four-probe method according to JISK7149.
  • When measuring high resistance it can be measured using, for example, Hiresta UP MCP-HT450 (Dia Instruments, 10 V, 10 seconds).
  • a carbon nanotube film for resistance value measurement can be produced by drying the filtered material together with the filter and the filter used for filtering at 60 ° C. for 2 hours.
  • the thickness of the produced carbon nanotube film can be measured by peeling it from the filter with tweezers. If the carbon nanotube film cannot be peeled off, measure the total thickness of the filter and carbon nanotube film, The thickness may be calculated by subtracting from the total thickness.
  • a membrane filter As a filter for filtration, a membrane filter (OMNIPOREMBRANE FILTERS, FILTER TYPE: 1.0 ⁇ m JA, 47 mm ⁇ ) can be preferably used.
  • the pore size of the filter may be 1.0 ⁇ m or less as long as the filtrate passes through.
  • the material of the filter needs to be a material that does not dissolve in NMP and ethanol, and it is preferable to use a filter made of fluororesin (PTFE).
  • the carbon nanotubes contained in the aggregate of carbon nanotubes of the present invention are 50% or more double-walled carbon nanotubes.
  • the content of the double-walled carbon nanotube is evaluated by the number of double-walled carbon nanotubes in 100 arbitrary carbon nanotubes contained in the carbon nanotube aggregate when the carbon nanotube aggregate is observed with a transmission electron microscope.
  • the carbon nanotube aggregate is observed with a transmission electron microscope at a magnification of 400,000, and a layer of 100 carbon nanotubes arbitrarily extracted from a field of view in which 10% or more of the field area is a carbon nanotube in a 75 nm square field of view. Evaluate the number. When 100 lines cannot be measured in one field of view, measurement is performed from a plurality of fields until 100 lines are obtained.
  • one carbon nanotube is counted as one if a part of the carbon nanotube is visible in the field of view, and both ends are not necessarily visible.
  • it may be connected outside the field of view and become one, but in that case, it is counted as two.
  • carbon nanotubes have a higher degree of graphitization as the number of layers decreases, that is, they have higher conductivity, and the degree of graphitization tends to decrease as the number of layers increases. Since the double-walled carbon nanotube has more layers than the single-walled carbon nanotube, the durability is high. In addition, double-walled carbon nanotubes have a high degree of graphitization and are therefore highly conductive. Therefore, the larger the proportion of double-walled carbon nanotubes, the better. In the aggregate of carbon nanotubes of the present invention, the ratio of the double-walled carbon nanotubes when measured by the above method needs to be 50% or more, that is, 50 or more out of 100, and 60 or more out of 100 must be 2 or more. Single-walled carbon nanotubes are preferable, and 70 or more of 100 are more preferably double-walled carbon nanotubes.
  • the quality of the carbon nanotube aggregate can be evaluated by a Raman G / D ratio.
  • Raman G / D ratio when evaluating the Raman G / D ratio, Raman spectroscopic analysis is performed at a wavelength of 532 nm. The higher the G / D ratio is, the better, but if it is 30 or more, it can be said to be a high quality carbon nanotube aggregate.
  • the G / D ratio is preferably 200 or less.
  • the G / D ratio is preferably 40 or more and 200 or less, more preferably 50 or more and 150 or less.
  • solid Raman spectroscopy such as aggregates of carbon nanotubes may vary depending on sampling.
  • the Raman shift observed in the vicinity of 1590 cm ⁇ 1 in the Raman spectrum obtained by the Raman spectroscopic analysis is called a graphite-derived G band
  • the Raman shift observed in the vicinity of 1350 cm ⁇ 1 is D derived from defects in amorphous carbon or graphite. Called a band. It is shown that the higher the ratio of the G band and the D band, that is, the higher the G / D ratio, the higher the degree of graphitization and the higher the quality.
  • the combustion peak temperature of the carbon nanotube aggregate of the present invention is required to be 550 ° C. or higher and 700 ° C. or lower. Preferably they are 560 degreeC or more and 650 degrees C or less.
  • the combustion peak temperature here is measured by a differential thermal analyzer.
  • a differential thermal analyzer for example, a differential thermal / thermogravimetric analyzer DTG-60A manufactured by Shimadzu Corporation can be used. Place a sample of ⁇ -alumina as a reference and about 1-10 mg each in a platinum pan in a differential thermal analyzer, and weigh it in air at a rate of 10 ° C / min. By doing so, the combustion peak temperature of the sample can be measured.
  • the combustion peak temperature is considered to correlate with the quality, diameter and bundle thickness of the carbon nanotube.
  • combustion is thought to be an oxidation reaction due to the attack of oxygen molecules, so if the degree of graphitization of carbon nanotubes is low, or if there are many defects in the graphene sheets that make up the carbon nanotubes, The combustion peak temperature is lowered.
  • carbon nanotubes having a large diameter usually have a tendency to lower the degree of graphitization, and therefore the combustion peak temperature is lowered.
  • the carbon nanotubes with a small diameter usually form a bundle. Even if each one is the same carbon nanotube, if the bundle is thick, the carbon nanotubes inside the bundle are not easily attacked by oxygen, so the combustion peak temperature of the aggregate of carbon nanotubes rises. On the contrary, when the bundle is thinned, the carbon nanotubes inside the bundle are also easily subjected to oxygen attack, so that the combustion peak temperature of the carbon nanotube aggregate is lowered.
  • the aggregate of carbon nanotubes having a combustion peak temperature higher than 700 ° C. is high in quality and thin in diameter, but the bundle is thick and it is difficult to dissociate the bundle, so that it is difficult to disperse in a solvent or resin.
  • An aggregate of carbon nanotubes having a combustion peak temperature lower than 550 ° C. has poor quality, that is, has a low degree of graphitization, and therefore does not improve its characteristics when deployed in various applications. From the above points, the combustion peak temperature is preferably in the above range in terms of quality and dispersibility.
  • the proportion of three or more layers of carbon nanotubes contained in the carbon nanotube aggregate is 10% or less.
  • the heat resistance increases as the number of carbon nanotube layers increases. Therefore, even if the carbon nanotube aggregate contains single-walled carbon nanotubes or amorphous carbon with low heat resistance, these can be selectively oxidized and removed by the vapor phase oxidation method described later, The purity of the double-walled carbon nanotube can be improved. However, if the carbon nanotube aggregate contains a large amount of three or more layers of carbon nanotubes, it is difficult to selectively remove them from the double-walled carbon nanotubes.
  • the ratio of the multi-walled carbon nanotubes having three or more layers in the carbon nanotube aggregate is preferably 10% or less. More preferably, it is 8% or less.
  • the content of the three or more carbon nanotubes is also evaluated by the number of the three or more carbon nanotubes in any 100 carbon nanotubes in the aggregate of carbon nanotubes, as described above.
  • the ratio of oxygen atoms to carbon atoms in the carbon nanotube aggregate of the present invention is preferably less than 4% (atomic%).
  • the ratio of oxygen atoms to carbon atoms can be measured by using surface composition analysis of X-ray photoelectron spectroscopy (XPS). For example, measurement can be performed using conditions of excitation X-ray: Monochromatic AlK ⁇ 1,2 line, X-ray diameter: 1000 ⁇ m, photoelectron escape angle: 90 ° (detector inclination with respect to the sample surface).
  • the ratio of oxygen atoms to carbon atoms being less than 4% means that the ratio of oxygen atoms to carbon atoms is less than 4% (atomic%) as a result of surface composition analysis by X-ray photoelectron spectroscopy (XPS).
  • the carbon nanotube aggregate is of high quality.
  • a large proportion of oxygen atoms means that there are many oxygen atom-containing functional groups (C ⁇ O, C—O, etc.), indicating that there are many defects in the graphite structure of carbon nanotubes.
  • the fact that the ratio of oxygen atoms to carbon atoms is small indicates that there are few oxygen atom-containing functional groups (C ⁇ O, C—O, etc.) introduced into the carbon nanotube. More preferably, the ratio of oxygen atoms to carbon atoms is 3% (atomic%) or less.
  • the aggregate of carbon nanotubes of the present invention preferably has a weight loss rate from 200 ° C. to 400 ° C. of 5% or less in thermogravimetry when the temperature is raised at 10 ° C./min.
  • the weight reduction rate from 200 ° C. to 400 ° C. in thermogravimetry when the temperature is raised at 10 ° C./min can be measured by thermal analysis of the carbon nanotube aggregate in the atmosphere.
  • a sample of about 1 mg is placed in a thermogravimetric analyzer (for example, a differential thermal / thermogravimetric analyzer DTG-60A manufactured by Shimadzu Corporation), and is heated from room temperature to 900 ° C. at a heating rate of 10 ° C./min. The temperature is raised to ° C.
  • the weight loss between 200 ° C. and 400 ° C. and the weight loss between 200 ° C. and 900 ° C. are measured, and the weight between 200 ° C. and 400 ° C. with respect to the weight loss between 200 ° C. and 900 ° C.
  • the rate of reduction is the weight reduction rate.
  • carbon impurities other than carbon nanotubes such as amorphous carbon
  • the weight loss rate from 200 ° C. to 400 ° C. increases as the carbon impurity increases.
  • the larger the amount of carbon impurities the lower the characteristics of the carbon nanotube aggregate.
  • the concentration of methane is preferably 10% by volume or less with respect to the entire raw material gas used in the reaction.
  • the volume% said here can be shown by the volume% of gas measured at 10125 Pa (1 atm) and 25 degreeC.
  • methane is a hardly decomposable gas, it was usual to distribute methane at a high concentration in order to increase the yield.
  • high-concentration methane is allowed to flow at a heating temperature, a large amount of by-products such as amorphous carbon is generated due to vapor phase decomposition of methane itself and side reactions on the catalyst.
  • the concentration of methane in the raw material gas is more preferably 7% by volume or less, and further preferably 5% by volume or less. Since the lower limit of explosion of methane is 5% by volume or less, if it is within this range, it is not necessary to provide an excessive safety device or the like in the reaction apparatus, so mass production is easy. However, if the concentration of methane is too dilute, the production efficiency of carbon nanotubes is lowered. Therefore, the concentration of methane in the raw material gas is preferably 1% by volume or more.
  • methane is used for the reaction with the diluent gas.
  • the diluent gas is not particularly limited, but a gas other than oxygen gas is preferably used.
  • Oxygen is not usually used because it may explode, but it may be used if it is outside the explosion range.
  • Nitrogen, argon, hydrogen, helium, neon, etc. are preferably used as the dilution gas.
  • Hydrogen is preferable because it is effective in activating the catalytic metal.
  • a gas having a large molecular weight such as argon has a large annealing effect and is preferable for the purpose of annealing.
  • nitrogen and argon are particularly preferable.
  • the linear velocity of the source gas containing methane is 4 cm / sec or more and 15 cm / sec or less.
  • methane is a hardly decomposable gas
  • a large amount of by-products such as amorphous carbon is generated by vapor phase decomposition of methane itself or side reaction on the catalyst.
  • the linear velocity of the source gas is more preferably 4 cm / sec or more and 10 cm / sec or less, and further preferably 4 cm / sec or more and 9 cm / sec or less.
  • the catalyst greatly fluctuates, deviates from the reaction temperature range (soaking zone), and a high-quality carbon nanotube aggregate cannot be obtained.
  • the temperature at which the catalyst and the raw material gas are brought into contact is 500 to 1200 ° C, more preferably 700 ° C to 1000 ° C, and still more preferably 750 ° C to 950 ° C.
  • the temperature is lower than 500 ° C.
  • the yield of the carbon nanotube aggregate is deteriorated.
  • the temperature is higher than 1200 ° C.
  • the material of the reactor to be used is restricted, and bonding between the carbon nanotubes starts, making it difficult to control the shape of the carbon nanotubes.
  • the reactor may be brought to the reaction temperature while the raw material gas is in contact with the catalyst, or the supply of the raw material gas may be started after the reactor is brought to the reaction temperature after completion of the pretreatment by heat.
  • the catalyst may be pretreated with heat before the reaction for generating the carbon nanotube aggregate.
  • the time and temperature of heat pretreatment are not particularly limited. By performing the pretreatment with heat, the catalyst may be brought into a more active state. At this time, it is also possible to flow gas.
  • As the gas nitrogen, argon, hydrogen, helium, neon or the like is preferably used. Hydrogen is preferable because it is effective in activating the catalytic metal.
  • a gas having a large molecular weight such as argon has a large annealing effect and is preferable for the purpose of annealing. Nitrogen and / or argon are particularly preferable.
  • the pretreatment with heat and the reaction for generating the carbon nanotube aggregate be performed under reduced pressure or atmospheric pressure.
  • the reaction system can be reduced in pressure with a vacuum pump or the like.
  • the reaction system is not particularly limited, but the reaction is preferably carried out using a vertical fluidized bed reactor.
  • the vertical fluidized bed reactor is a reactor installed so that methane flows in the vertical direction (hereinafter also referred to as “longitudinal direction”). Methane flows in the direction from one end of the reactor toward the other end and passes through the catalyst layer.
  • a reactor having a tube shape can be preferably used.
  • the vertical direction includes a direction having a slight inclination angle with respect to the vertical direction (for example, 90 ° ⁇ 15 °, preferably 90 ° ⁇ 10 ° with respect to the horizontal plane). Preferred is the vertical direction.
  • the supply part and the discharge part of methane do not necessarily need to be the end part of the reactor, and methane may flow in the above direction and pass through the catalyst layer in the flow process.
  • the catalyst is in a state of being present in the entire horizontal cross-sectional direction of the reactor in the vertical fluidized bed reactor, and a fluidized bed is formed during the reaction. By doing in this way, a catalyst and methane can be made to contact effectively.
  • a horizontal reactor in order to effectively bring the catalyst into contact with methane, in order to make it exist in the entire cross section of the reactor in a direction perpendicular to the flow of methane, the catalyst is viewed from the left and right due to gravity. It is necessary to pinch.
  • the carbon nanotube aggregate formation reaction the carbon nanotube aggregate is generated on the catalyst as the reaction proceeds, and the volume of the catalyst is increased. Therefore, the method of sandwiching the catalyst from the left and right is not preferable.
  • the reactor is set to a vertical type, a stage through which gas can permeate is installed in the reactor, and the catalyst is placed on the reactor, so that the catalyst can be evenly distributed in the cross-sectional direction of the reactor without sandwiching the catalyst from both sides.
  • a catalyst can be present, and a fluidized bed can also be formed when methane is passed in the vertical direction.
  • the state in which the catalyst is present on the entire surface in the horizontal sectional direction of the vertical fluidized bed reactor refers to a state in which the catalyst spreads throughout the horizontal sectional direction and the platform at the bottom of the catalyst cannot be seen. As a preferable embodiment in such a state, for example, there are the following modes.
  • FIG. 1A is a conceptual diagram showing a state in which a stand 2 on which a catalyst is placed is installed in a reactor 1 and a catalyst 3 is present on the entire horizontal cross-sectional direction of the reactor.
  • FIG. 1 (b) is a conceptual diagram showing a state in which a platform 2 on which a catalyst is placed is installed in the reactor 1, and a mixture 4 of an object other than the catalyst and the catalyst exists on the entire cross-sectional direction of the reactor. It is.
  • FIG. 1C is a conceptual diagram showing a catalyst state in which the catalyst 5 sprayed from the upper part of the reactor 1 spreads over the entire horizontal cross-sectional direction of the reactor.
  • the vertical fluidized bed reactor there are a mode in which the catalyst as described above C is dropped from the upper part of the reactor by spraying or a mode in which a catalyst generally called a boiling bed type flows (a method according to the above A and B). Can be mentioned.
  • the fluidized bed reactor can continuously synthesize by continuously supplying the catalyst and continuously removing the aggregate including the catalyst and the carbon nanotube aggregate after the reaction. It is preferable because it can be obtained efficiently.
  • the raw material methane and the catalyst are in uniform and efficient contact with each other, so that the carbon nanotube synthesis reaction is performed uniformly, the catalyst coating with impurities such as amorphous carbon is suppressed, and the catalyst activity is long. It is thought to continue.
  • a horizontal reactor In contrast to a vertical reactor, a horizontal reactor has a laterally (horizontal) reactor in which a catalyst placed on a quartz plate is placed, and methane passes over the catalyst. It refers to a reaction device in a mode of contacting and reacting. In this case, carbon nanotubes are generated on the catalyst surface, but hardly react because methane does not reach the inside of the catalyst. On the other hand, in the vertical reactor, the raw material methane can be brought into contact with the entire catalyst, so that a large amount of carbon nanotube aggregates can be efficiently synthesized.
  • the reactor is preferably heat resistant, and is preferably made of a heat resistant material such as quartz or alumina.
  • the catalyst in the present invention contains a catalytic metal.
  • the type of the catalyst metal is not particularly limited, but a metal of group 3 to 12, preferably a metal of group 5 to 11, is preferably used. Among these, V, Mo, Mn, Fe, Co, Ni, Pd, Pt, Rh, W, Cu and the like are preferable. More preferred are Fe, Co and Ni, and most preferred is Fe.
  • the metal is not necessarily a zero-valent state. Although it can be presumed that the metal is in a zero-valent state during the reaction, it may be a compound or metal species containing a wide variety of metals.
  • organic salts or inorganic salts such as formate, acetate, trifluoroacetate, ammonium citrate, nitrate, sulfate, halide salt, complex salts such as ethylenediaminetetraacetate complex and acetylacetonate complex are used. It is done.
  • the catalyst metal is preferably fine particles. The particle diameter of the fine particles is preferably 0.5 to 10 nm. If the catalytic metal is fine, carbon nanotubes with a small outer diameter are likely to be generated. Only one type of catalyst metal may be used, or two or more types may be used. When two or more kinds of catalyst metals are used, it is particularly preferable to include Fe.
  • the catalyst metal may be in a state of being supported on a carrier.
  • the carrier is not particularly limited, but a carrier selected from silica, alumina, magnesia, titania and zeolite is preferably used. Among these, magnesia is particularly preferable.
  • magnesia a commercially available product may be used, or a synthesized product may be used.
  • magnesium metal is heated in air, magnesium hydroxide is heated to 850 ° C. or higher, and magnesium carbonate 3MgCO 3 .Mg (OH) 2 .3H 2 O is heated to 950 ° C. or higher. There are methods.
  • the method for supporting the catalyst metal on the carrier is not particularly limited.
  • a carrier is impregnated in a non-aqueous solution (for example, ethanol solution) or an aqueous solution in which a catalyst metal salt to be supported is dissolved, sufficiently dispersed and mixed by stirring or ultrasonic irradiation, and then dried (impregnation method).
  • heating may be performed at a high temperature (300 to 1000 ° C.) in a gas selected from air, oxygen, nitrogen, hydrogen, an inert gas, and a mixed gas thereof or in a vacuum.
  • the optimum catalyst metal loading varies depending on the pore volume, outer surface area, and loading method of magnesia, but it is preferable to load 0.1 to 20% by weight of catalyst metal with respect to magnesia. When two or more kinds of catalyst metals are used, the ratio is not limited.
  • the contact efficiency between the catalyst and methane is improved, and more high-quality carbon nanotubes are synthesized efficiently and in large quantities. Is possible.
  • the bulk density of the catalyst is less than 0.30 g / mL, it is difficult to handle the catalyst.
  • the catalyst may be greatly swollen in the vertical reactor when contacting with methane, and the catalyst may be out of the soaking zone of the reactor to obtain high-quality carbon nanotubes. Becomes difficult.
  • the bulk density of the catalyst exceeds 2.00 g / mL, it will be difficult for the catalyst and methane to contact uniformly and efficiently, and it will also be difficult to obtain high-quality carbon nanotubes. If the bulk density of the catalyst is too large, when the catalyst is installed in a vertical reactor, the catalyst will be tightly packed, making it impossible to uniformly contact methane, making it difficult to produce high-quality carbon nanotubes. . When the bulk density of the catalyst is in the above range, the contact efficiency between methane and the catalytic metal is increased, so that uniform and high-quality carbon nanotubes can be produced efficiently and in large quantities.
  • the bulk density of the catalyst is preferably 0.30 g / mL or more and 2.00 g / mL or less.
  • the bulk density of the catalyst is more preferably 0.40 g / mL or more and 1.70 g / mL or less, and further preferably 0.50 g / mL or more and 1.50 g / mL or less.
  • Bulk density is the mass of powder per unit bulk volume.
  • the bulk density measurement method is shown below.
  • the bulk density of the powder may be affected by the temperature and humidity at the time of measurement.
  • the bulk density referred to here is a value measured at a temperature of 20 ⁇ 10 ° C. and a humidity of 60 ⁇ 10%.
  • Using a 50 mL graduated cylinder as a measuring vessel add powder to occupy a predetermined volume while tapping the bottom of the graduated cylinder. In measuring the bulk density, it is preferable to add 10 mL or more of powder.
  • the carbon nanotube production catalyst used for the measurement is 20 g ⁇ 5 g.
  • the quantity of the catalyst for carbon nanotube manufacture is less than the said quantity, it shall measure by the quantity which can be evaluated.
  • the bulk density of the catalyst is affected when the catalyst is brought into contact with methane at the heating temperature. At this time, it is unclear how the state of the catalyst changes compared to the time of catalyst preparation (before reaction). However, the bulk density of the catalyst does not change greatly before and after the reaction. Therefore, high quality carbon nanotubes can be obtained by setting the bulk density of the catalyst at the time of catalyst preparation (before reaction) within the above range.
  • the contact time between methane and the catalyst is preferably 8.0 ⁇ 10 ⁇ 2 g ⁇ min / mL or more and 1.0 ⁇ 10 0 g ⁇ min / mL or less.
  • the contact time is a value obtained by dividing the amount of catalyst (g) subjected to the reaction by the flow rate of methane (mL / min). If the contact time is too long, side reactions occur and amorphous carbon tends to increase, so 1.0 ⁇ 10 0 g ⁇ min / mL or less is preferable. Moreover, when the contact time is short, the production efficiency of carbon nanotubes deteriorates and the yield is greatly reduced. For this reason, 8.0 ⁇ 10 ⁇ 2 g ⁇ min / mL or more is preferable.
  • the aggregate of carbon nanotubes produced by the production process as described above contains impurities such as single-walled carbon nanotubes and amorphous carbon in addition to the double-walled carbon nanotubes. It is preferable to perform gas phase oxidation on the aggregate of carbon nanotubes generated as described above. By performing vapor phase oxidation, it is possible to selectively remove impurities such as amorphous carbon and single-walled carbon nanotubes having low heat resistance in the product, and the purity of the double-walled carbon nanotubes can be improved.
  • the oxidation temperature is affected by the atmospheric gas, so it is preferable to perform the baking treatment at a relatively low temperature when the oxygen concentration is high and at a relatively high temperature when the oxygen concentration is low. .
  • the firing treatment is preferably performed within the range of the combustion peak temperature of the carbon nanotube aggregate ⁇ 50 ° C. Even if the firing treatment is performed at a combustion peak temperature of less than ⁇ 50 ° C., impurities and single-walled carbon nanotubes are difficult to remove, and it is considered difficult to improve the purity of the double-walled carbon nanotubes. Further, when the baking treatment is performed at the combustion peak temperature + 50 ° C.
  • the temperature for the baking treatment is preferably selected in the range of 300 to 900 ° C., more preferably 400 to 600 ° C.
  • a lower temperature range is selected, and when the oxygen concentration is lower than the atmosphere, a higher temperature range is selected.
  • the combustion peak temperature of the carbon nanotube aggregate can be measured by thermal analysis using a differential thermal analyzer.
  • a differential thermal analyzer eg, differential thermal / thermogravimetric analyzer DTG-60A manufactured by Shimadzu Corporation
  • DTG-60A thermogravimetric analyzer
  • the firing time is not particularly limited as long as the carbon nanotube of the present invention is obtained.
  • the reaction conditions can be adjusted by, for example, lengthening the firing time when the firing temperature is low and shortening the firing time when the firing temperature is high.
  • the firing time is preferably 5 minutes to 24 hours, more preferably 10 minutes to 12 hours, and even more preferably 30 minutes to 5 hours.
  • Firing is preferably performed in the air, but may be performed in an oxygen / inert gas with a controlled oxygen concentration.
  • the oxygen concentration at this time is not particularly limited. Oxygen may be appropriately set in the range of 0.1% to 100%.
  • As the inert gas helium, nitrogen, argon or the like is used.
  • the gas phase oxidation can also be performed by a method in which oxygen or a mixed gas containing oxygen is intermittently brought into contact with the carbon nanotubes to perform a firing treatment.
  • the treatment can be performed at a relatively high temperature. This is because, since oxygen or a mixed gas containing oxygen is intermittently flowed, even if oxidation occurs, the reaction stops immediately when oxygen is consumed.
  • the temperature range is preferably about 400 to 1200 ° C., more preferably about 450 to 950 ° C. As described above, the temperature is about 500 to 1200 ° C. during the production of carbon nanotubes. Therefore, when the firing process is performed immediately after the production of the carbon nanotube, it is preferable to perform such an intermittent firing process.
  • the gas phase oxidation as described above is preferably performed until the Raman G / D ratio of the aggregate of carbon nanotubes after the gas phase oxidation at a measurement wavelength of 532 nm reaches 30 or more.
  • the Raman G / D ratio can be improved to 30 or more. Is possible.
  • the carbon nanotube aggregate of the present invention it is possible to produce a carbon nanotube molded body with extremely high conductivity.
  • a carbon nanotube molded body having very high conductivity and excellent strength can be produced.
  • the carbon nanotube molded body refers to a carbon nanotube aggregate that has been shaped by molding or processing. Molding or processing refers to all operations that pass through operations and processes that change the shape of the carbon nanotube aggregate. Examples of the carbon nanotube molded body include yarns, chips, pellets, sheets, blocks, and the like made of a carbon nanotube aggregate. A combination of these, or a result obtained by further molding or processing is also a carbon nanotube molded body.
  • the method for forming the carbon nanotube aggregate is not particularly limited.
  • the carbon nanotube aggregate sheet can be produced by dispersing the carbon nanotube aggregate in a solvent, filtering the dispersion, and drying. It is also possible to form a carbon nanotube aggregate thread by discharging a dispersion liquid in which the carbon nanotube aggregate is dispersed into a thread from a thin die and impregnating the coagulation bath.
  • the aggregate of carbon nanotubes of the present invention can be made into a composition having very high conductivity, excellent strength, or excellent thermal conductivity by mixing or dispersing in a substance other than carbon nanotubes.
  • Substances other than carbon nanotubes are, for example, resin, metal, glass, liquid dispersion medium, and the like, and may be an adhesive, cement, gypsum, ceramics, or the like.
  • the composition containing an aggregate of carbon nanotubes means all substances in a state where the aggregate of carbon nanotubes is mixed or dispersed in these substances.
  • dispersion refers to a state in which the carbon nanotubes in the carbon nanotube aggregate are loosened one by one, in a bundled state, or in a state where bundles of various thicknesses are mixed from one, It is sufficient that the nanotubes are evenly dispersed in the substance.
  • the mixed state here refers to a state in which the carbon nanotube aggregates are scattered unevenly in the substance, or simply a mixture of the solid carbon nanotube aggregate and the solid substance. Is also included.
  • each component in the composition is as follows. That is, the composition containing the aggregate of carbon nanotubes preferably contains 0.01% by weight or more of carbon nanotubes, and more preferably contains 0.1% by weight or more.
  • the upper limit of the content is preferably 20% by weight or less. When the content of the carbon nanotubes exceeds 20% by weight, it may be difficult to handle the composition.
  • the content of carbon nanotubes is more preferably 5% by weight or less, still more preferably 2% by weight or less.
  • a molded article made of a composition containing an aggregate of carbon nanotubes is a molded article that has been molded or processed by operations such as compression, cutting, crushing, stretching, and punching among solid compositions. It is the one that has been solidified again in a specific form after melting.
  • the resin is not particularly limited as long as it can mix or disperse the carbon nanotube aggregate of the present invention, and may be a natural resin or a synthetic resin.
  • a thermosetting resin or a thermoplastic resin can be suitably used as the synthetic resin.
  • a composition in which a substance other than carbon nanotubes is a thermoplastic resin is preferable because the obtained molded article has excellent impact strength and can be subjected to press molding and injection molding with high molding efficiency.
  • thermosetting resin is not particularly limited.
  • unsaturated polyester resin vinyl ester resin, epoxy resin, cyanate ester resin, benzoxazine resin, phenol (resole type) resin, urea melamine resin, thermosetting polyimide, These copolymers, modified products thereof, or resins obtained by blending two or more of them can be used. Further, in order to further improve impact resistance, a resin obtained by adding a flexible component such as elastomer, synthetic rubber, natural rubber or silicone to the thermosetting resin may be used.
  • thermoplastic resin is not particularly limited.
  • polyester resins such as liquid crystal polyester and non-liquid crystal polyester
  • polyolefins such as polyethylene, polypropylene, and polybutylene
  • styrene resins polyoxymethylene, polyamide, polycarbonate resin, Polymethylene methacrylate, polyvinyl chloride, polyphenylene sulfide resin, polyphenylene ether, polyamide resin, thermoplastic polyimide, polyamideimide, polyetherimide, polysulfone, polyethersulfone, polyketone, polyetherketone, polyetherketoneketone, Polyarylate, polyether nitrile, phenol (novolak type, etc.) resin, phenoxy resin, polytetrafluoroethylene, etc.
  • Fluorine-based resins polystyrene-based, polyolefin-based, polyurethane-based, polyester-based, polyamide-based, polybutadiene-based, polyisoprene-based, fluorine-based thermoplastic elastomers, their copolymers, modified products, and these resins
  • examples include resins blended in two or more types.
  • a resin obtained by adding a flexible component such as another elastomer, synthetic rubber, natural rubber, or silicone to the thermoplastic resin may be used.
  • Resin may be only synthetic rubber, natural rubber, or elastomer such as silicone.
  • Other examples include polyalcohol resins typified by polyvinyl alcohol, polycarboxylic acid resins typified by polyvinyl acetate, acrylic resins such as polyacrylic acid esters, and polyacrylonitrile.
  • vinyl-based adhesives such as acrylic, silicone-based, vinyl acetate resin, vinyl ether resin, and pressure-sensitive adhesives can also be mentioned.
  • the metal aluminum, copper, silver, gold, iron, nickel, zinc, lead, tin, cobalt, chromium, titanium, tungsten, etc. can be used alone or in combination.
  • the glass include soda lime glass, lead glass, and borate glass.
  • the aggregate of carbon nanotubes can be a composition dispersed in a liquid dispersion medium (hereinafter also referred to as a carbon nanotube dispersion).
  • the carbon nanotube dispersion liquid it is also preferable to further contain an additive such as a surfactant, a conductive polymer or a non-conductive polymer.
  • an additive such as a surfactant, a conductive polymer or a non-conductive polymer. This is because the above-described surfactant and certain polymer materials are useful for improving the dispersibility and dispersion stabilization capability of carbon nanotubes.
  • the content of an additive such as a surfactant is not particularly limited, but is preferably 0.1 to 50% by weight, more preferably 0.2 to 30% by weight.
  • the mixing ratio of the additive and carbon nanotube (additive / carbon nanotube) is not particularly limited, but is preferably 0.1 to 20, more preferably 0.3 to 10 by weight.
  • the carbon nanotube dispersion of the present invention may contain additives other than carbon nanotubes, surfactants, and substances other than the dispersion medium.
  • Surfactants are classified into ionic surfactants and nonionic surfactants, but any surfactant can be used in the present invention.
  • examples of the ionic surfactant include the following surfactants. Such surfactants can be used alone or in admixture of two or more.
  • the ionic surfactant is classified into a cationic surfactant, an amphoteric surfactant and an anionic surfactant.
  • the cationic surfactant include alkylamine salts and quaternary ammonium salts.
  • amphoteric surfactants include alkylbetaine surfactants and amine oxide surfactants.
  • anionic surfactants include alkylbenzene sulfonates such as dodecylbenzene sulfonic acid, aromatic sulfonic acid surfactants such as dodecyl phenyl ether sulfonate, monosoap anionic surfactants, ether sulfate-based interfaces Activators, phosphate surfactants, carboxylic acid surfactants.
  • aromatic ionic surfactants include those that contain an aromatic ring because of their excellent dispersibility, dispersion stability, and high concentration.
  • aromatic ionic surfactants An aromatic ionic surfactant such as alkylbenzene sulfonate and dodecyl phenyl ether sulfonate is particularly preferable.
  • nonionic surfactants include the following surfactants. Such surfactants can be used alone or in admixture of two or more.
  • nonionic surfactants include sugar ester surfactants such as sorbitan fatty acid esters and polyoxyethylene sorbitan fatty acid esters, fatty acid ester surfactants such as polyoxyethylene resin acid esters and polyoxyethylene fatty acid diethyl , Polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, ether surfactants such as polyoxyethylene / polypropylene glycol, polyoxyalkylene octyl phenyl ether, polyoxyalkylene nonyl phenyl ether, polyoxyalkyl dibutyl phenyl ether, poly Oxyalkyl styryl phenyl ether, polyoxyalkyl benzyl phenyl ether, polyoxyalkyl bisphenyl ether, polyoxyalkyl Aromatic anionic surfactants such as mill phenyl ether. Of these, aromatic nonionic surfactants are preferred because of their excellent dispersibility, dispersion stability, and high
  • polymer material of the conductive polymer or non-conductive polymer examples include water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polystyrene sulfonate ammonium salt, polystyrene sulfonate sodium salt, carboxymethyl cellulose sodium salt (Na-CMC). ), Sugar polymers such as methyl cellulose, hydroxyethyl cellulose, amylose, cycloamylose, and chitosan.
  • conductive polymers such as polythiophene, polyethylenedioxythiophene, polyisothianaphthene, polyaniline, polypyrrole, polyacetylene, and derivatives thereof can also be used.
  • the method for producing the carbon nanotube dispersion for example, a carbon nanotube aggregate and additives, and a dispersion medium commonly used for coating production, such as a ball mill, bead mill, sand mill, roll mill, homogenizer, attritor, resolver. , A paint shaker or the like) to produce a dispersion.
  • the carbon nanotube dispersion liquid is preferably subjected to size fractionation by centrifugation, filter filtration or the like before coating. For example, by centrifuging the dispersion, undispersed carbon nanotubes, excessive amounts of additives, catalysts that may be mixed during carbon nanotube synthesis, etc. are precipitated.
  • the carbon nanotubes dispersed in the liquid can be collected in the form of a liquid. Undispersed carbon nanotubes, impurities, and the like can be removed as precipitates, whereby reaggregation of the carbon nanotubes can be prevented and the stability of the dispersion can be improved. Furthermore, in strong centrifugal force, it can isolate
  • the centrifugal force at the time of centrifugation may be 100 G or more, preferably 1000 G or more, and more preferably 10,000 G or more. Although there is no restriction
  • the filter used for filter filtration can be appropriately selected between 0.05 ⁇ m and 0.2 ⁇ m. Thereby, it is possible to remove undispersed carbon nanotubes and impurities having a relatively large size among impurities that may be mixed during synthesis of the carbon nanotubes.
  • the composition after size fractionation is prepared in the above range in anticipation of the fractionated amount.
  • the carbon nanotubes can be separated according to the length of the carbon nanotubes, the number of layers, the presence or absence of a bundle structure, and the like.
  • the liquid dispersion medium may be an aqueous solvent or a non-aqueous solvent.
  • Non-aqueous solvents include hydrocarbons (toluene, xylene, etc.), chlorine-containing hydrocarbons (methylene chloride, chloroform, chlorobenzene, etc.), ethers (dioxane, tetrahydrofuran, methyl cellosolve, etc.), ether alcohols (ethoxyethanol, methoxy) Ethoxyethanol, etc.), esters (methyl acetate, ethyl acetate, etc.), ketones (cyclohexanone, methyl ethyl ketone, etc.), alcohols (ethanol, isopropanol, phenol, etc.), lower carboxylic acids (acetic acid, etc.), amines (triethylamine, triethylamine, etc.) Methanolamine, etc.), nitrogen-containing polar solvents (N, N-dimethylformamide, nitromethan
  • the dispersion medium is preferably a solvent selected from water, alcohol, toluene, acetone, ether, and combinations thereof.
  • a solvent selected from water, alcohol, toluene, acetone, ether, and combinations thereof.
  • polar solvents such as water, alcohols and amines are preferably used.
  • a liquid thing at normal temperature as a binder so that it may mention later, itself can also be used as a dispersion medium.
  • the conductive composite of the present invention is obtained by forming a conductive layer containing the above carbon nanotube aggregate on a substrate.
  • the carbon nanotube dispersion can be used as a method for forming the conductive layer.
  • the carbon nanotube dispersion is applied by a known application method such as spray coating, dip coating, spin coating, knife coating, kiss coating, gravure coating, screen printing, inkjet printing, pad printing, other types of printing, or roll coating.
  • a method of coating on a substrate can be used.
  • the most preferred application method is roll coating.
  • the application may be performed any number of times, and two different application methods may be combined.
  • the dispersion medium of the dispersion liquid is volatile, unnecessary dispersion medium can be removed by methods such as air drying, heating, and decompression. Thereby, the carbon nanotube forms a three-dimensional stitch structure and is fixed to the base material.
  • the solvent for removing the additive is not particularly limited as long as it dissolves the additive, and may be an aqueous solvent or a non-aqueous solvent. Specifically, if it is an aqueous solvent, water and alcohols can be mentioned, and if it is a non-aqueous solvent, chloroform, acetonitrile and the like can be mentioned.
  • the amount of carbon nanotubes in the carbon nanotube composition can be increased. Further, in order to improve the conductivity with a small amount of carbon nanotubes, it is preferable that the carbon nanotubes are uniformly dispersed in the carbon nanotube composition, the bundle of carbon nanotubes is preferable, and the bundle of carbon nanotubes is loosened. More preferably, it is dispersed in a single state. The thickness of the bundle can be adjusted by changing the dispersion time of the dispersion method or the type of surfactant, conductive polymer or non-conductive polymer added as an additive.
  • the carbon nanotube dispersion can be used as a desired concentration by preparing a dispersion having a concentration higher than the desired carbon nanotube content and diluting with a solvent.
  • the concentration of carbon nanotubes may be reduced, or the carbon nanotubes may be manufactured with a low concentration from the beginning.
  • a transparent conductive composite body is obtained when a base material is a transparent base material, it is preferable.
  • a transparent substrate a film such as a PET film is particularly preferable.
  • the substrate not only a transparent substrate but also any substrate such as a colored substrate and fiber can be used.
  • the carbon nanotube dispersion liquid of the present invention can be used as an antistatic floor wall material when coated on a floor material or wall material in a clean room or the like, and can be used as an antistatic garment, mat, curtain or the like when coated on a fiber.
  • the present invention after forming a conductive layer on a substrate as described above, it is also preferable to overcoat the conductive layer with a binder material capable of forming an organic or inorganic transparent film. By overcoating, it is effective for further charge dispersion and movement.
  • the conductive composite can be obtained by containing a binder material capable of forming a transparent film in the carbon nanotube dispersion liquid, and applying to the base material, followed by heating as necessary to dry or cure the film. Can do.
  • the heating conditions at that time are appropriately set according to the binder type.
  • the binder is photocurable or radiation curable
  • the coating film is cured by irradiating the coating film with light or radiation immediately after coating, not by heat curing.
  • the radiation ionizing radiation such as electron beam, ultraviolet ray, X-ray and gamma ray can be used, and the irradiation dose is determined according to the binder type.
  • the binder material is not particularly limited as long as it is used for conductive paints.
  • Various transparent organic polymers or precursors thereof hereinafter sometimes referred to as “organic polymer binders” or inorganic polymers or A precursor thereof (hereinafter sometimes referred to as “inorganic polymer binder”) can be used.
  • the organic polymer binder may be any one of thermoplastic, thermosetting, photocurable, and radiation curable.
  • organic binders include polyolefins (polyethylene, polypropylene, etc.), polyamides (nylon 6, nylon 11, nylon 66, nylon 6, 10, etc.), polyesters (polyethylene terephthalate, polybutylene terephthalate, etc.), silicone polymers , Vinyl resins (polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyacrylate, polystyrene derivatives, polyvinyl acetate, polyvinyl alcohol, etc.), polyketone, polyimide, polycarbonate, polysulfone, polyacetal, fluororesin, phenol resin, urea resin, Melanin resin, epoxy resin, polyurethane, cellulosic polymer, proteins (gelatin, casein, etc.), chitin, polypeptide, polysaccharide, polynucleotide, etc.
  • Polymers, and precursors of these polymers can be mentioned. These can form an organic polymer transparent film simply by evaporation of a solvent, or by heat curing or curing by light irradiation or radiation irradiation.
  • inorganic polymer binders include sols of metal oxides such as silica, tin oxide, aluminum oxide, and zirconium oxide, or hydrolyzable or thermally decomposable organophosphorus compounds and organoboron compounds that are precursors of inorganic polymers.
  • organic metal compounds such as organic silane compounds, organic titanium compounds, organic zirconium compounds, organic lead compounds, and organic alkaline earth metal compounds.
  • hydrolyzable or thermally decomposable organometallic compounds are alkoxides or partial hydrolysates thereof, lower carboxylates such as acetate, and metal complexes such as acetylacetone.
  • a glassy inorganic polymer transparent film made of an oxide or a composite oxide can be formed.
  • the inorganic polymer transparent film has high hardness, excellent scratch resistance, and high transparency.
  • the conductive layer of the conductive composite of the present invention can further include a conductive organic material other than carbon nanotubes, a conductive inorganic material, or a combination of these materials.
  • a conductive organic material include buckyball, carbon black, fullerene, various carbon nanotubes, and particles containing them.
  • Conductive inorganic materials include aluminum, antimony, beryllium, cadmium, chromium, cobalt, copper, doped metal oxide, iron, gold, lead, manganese, magnesium, mercury, metal oxide, nickel, platinum, silver, steel, Examples include titanium, zinc, and particles containing them. Preferable examples include indium tin oxide, antimony tin oxide, and mixtures thereof.
  • the conductive composite containing these conductive materials is very advantageous for charge dispersion or movement. Further, a layer containing a conductive material other than these carbon nanotubes and a layer containing carbon nanotubes may be laminated.
  • the conductive layer using the carbon nanotube aggregate of the present invention exhibits excellent transparency, when a transparent substrate is used as the substrate, the conductive composite exhibits excellent transparency.
  • the surface resistance value of the conductive composite of the present invention is preferably less than 10 5 ⁇ / ⁇ .
  • various uses of transparent conductive coating such as EMI / RFI (electromagnetic interference) shield, low visibility, polymer electronics (eg, transparent conductive layer of OLED display, EL lamp, plastic chip) Useful for.
  • the surface resistance of the conductive composite of the present invention can be easily adjusted according to various applications by controlling the film thickness of the conductive layer. For example, increasing the film thickness tends to lower the surface resistance, and reducing the film thickness tends to increase the surface resistance.
  • a conductive coating for an EMI / RFI shield is generally acceptable if the surface resistance is less than 10 4 ⁇ / ⁇ , preferably 10 1 to 10 3 ⁇ / ⁇ .
  • transparent low visibility coatings are generally acceptable if the surface resistance is less than 10 3 ⁇ / ⁇ , preferably less than 10 2 ⁇ / ⁇ .
  • the surface resistance value is usually less than 10 4 ⁇ / ⁇ , preferably in the range of 10 ⁇ 2 to 10 0 ⁇ / ⁇ .
  • the conductive composite has a surface resistance of less than about 10 4 ⁇ / ⁇ .
  • the conductive composite of the present invention preferably has a surface resistance of less than 1 ⁇ 10 5 ⁇ / ⁇ , and the light transmittance at a wavelength of 550 nm satisfies the following conditions: Transmittance / transparency of conductive composite Substrate transmittance> 0.85
  • the surface resistance is 1 ⁇ 10 2 ⁇ / ⁇ or more and less than 5 ⁇ 10 4 ⁇ / ⁇ .
  • the weight loss from 200 ° C. to 400 ° C. and the weight loss from 200 ° C. to 900 ° C. are measured, and the weight loss between 200 ° C. and 400 ° C. with respect to the weight loss from 200 ° C. to 900 ° C.
  • the percentage of quantity was calculated.
  • the measurement sample was loaded into a spectrophotometer (Hitachi U-2100), and the light transmittance at a wavelength of 550 nm was measured.
  • the surface resistance value was measured using a 4-terminal 4-probe method according to JIS K7149 (established in December 1994) and a Loresta EP MCP-T360 (manufactured by Dia Instruments Co., Ltd.). When measuring high resistance, it was measured using Hiresta UP MCP-HT450 (manufactured by Dia Instruments, 10 V, 10 seconds).
  • Example 1> (Supporting catalytic metal salt on magnesia) 2.46 g of ammonium iron citrate (Wako Pure Chemical Industries, Ltd.) was dissolved in 500 mL of methanol (Kanto Chemical Co., Ltd.). To this solution, 100 g of magnesia (manufactured by Iwatani Chemical Industry Co., Ltd.) was added and stirred at room temperature for 60 minutes, and then methanol was removed under reduced pressure conditions at a water bath temperature of 40 ° C. to 60 ° C. using an evaporator. Then, it dried for 2 hours with a 120 degreeC dryer, and obtained the solid catalyst by which the catalyst metal salt was carry
  • the reactor 100 is a cylindrical quartz tube having an inner diameter of 75 mm and a length of 1700 mm.
  • a quartz sintered plate 101 is provided at the center, an inert gas and raw material gas supply line 104 at the lower part of the quartz tube, a waste gas line 105 at the upper part, a sealed catalyst feeder 102 and a catalyst charging line 103. It has.
  • a heater 106 is provided that surrounds the circumference of the reactor so that the reactor can be maintained at an arbitrary temperature.
  • the heater 106 is provided with an inspection port 107 so that the flow state in the apparatus can be confirmed.
  • the nitrogen flow rate of the raw material gas supply line 104 was increased to 16.5 L / min, and fluidization of the solid catalyst on the quartz sintered plate was started.
  • methane was further fed to the reactor at 0.78 L / min (methane concentration: 4.5 vol%, linear velocity: 6.5 cm / sec).
  • the flow was switched to a flow of only nitrogen gas to complete the synthesis.
  • the contact time between methane and the catalyst was 1.69 ⁇ 10 ⁇ 1 g ⁇ min / mL.
  • the heating was stopped and the mixture was allowed to stand at room temperature, and the composition containing the catalyst and the carbon nanotube aggregate was taken out from the reactor.
  • the obtained carbon nanotube aggregate was subjected to the following steps.
  • the obtained carbon nanotube aggregate was subjected to thermal analysis by the method described above.
  • the combustion peak temperature was 480 ° C.
  • the obtained carbon nanotube aggregate was subjected to thermal analysis.
  • the combustion peak temperature was 664 ° C.
  • the weight reduction amount from 200 degreeC to 400 degreeC is 5% of the weight reduction amount from 200 degreeC to 900 degreeC.
  • the carbon nanotube aggregate obtained as described above was observed with a high-resolution transmission electron microscope. As shown in FIG. 3, the carbon nanotube was composed of a clean graphite layer, and the number of the carbon nanotubes was two. Was observed. Two-layer carbon nanotubes occupied 80% or more (85) of 100 carbon nanotubes. The number of carbon nanotubes in three or more layers was 10% or less (seven).
  • the filter used was OMNIPOREMBRANE FILTERS, FILTER TYPE: 1.0 ⁇ m JA, 47 mm ⁇ .
  • the obtained carbon nanotube film was measured by Loresta EP MCP-T360 (manufactured by Dia Instruments Co., Ltd.) using a four-terminal four-probe method according to JIS K7149, the surface resistance was 0.249 ⁇ / ⁇ . there were. Accordingly, the volume resistivity is 1.62 ⁇ 10 ⁇ 3 ⁇ ⁇ cm.
  • the surface composition was evaluated by X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • the equipment used is ESCALAB 220iXL, the excitation X-ray is Monochromatic AlK ⁇ 1 , 2 and the X-ray diameter is 1000 ⁇ m.
  • the photoelectron escape angle is 90 °.
  • the ratio of oxygen atoms to carbon atoms was 2.5%.
  • a transparent conductive film was obtained by the above method.
  • Example 2 (Supporting catalytic metal salt on magnesia) In the same manner as in Example 1, the catalyst metal salt was supported on magnesia.
  • Example 1 (Synthesis of double-walled carbon nanotube) Example 1 except that the above catalyst was used to circulate nitrogen during the reaction at 11.0 L / min and methane at 0.52 L / min (methane concentration: 4.5 vol%, linear velocity: 4.3 cm / sec). Carbon nanotubes were synthesized by the same method. At this time, the contact time of methane and the catalyst was 2.54 ⁇ 10 ⁇ 1 g ⁇ min / mL. The obtained carbon nanotube aggregate was subjected to thermal analysis by the method described above. The combustion peak temperature was 475 ° C.
  • volume resistivity of carbon nanotube aggregate The volume resistivity of the carbon nanotube aggregate obtained as described above was measured in the same manner as in Example 1.
  • the carbon nanotube film had a thickness of 71.5 ⁇ m and a surface resistance value of 0.383 ⁇ / ⁇ . Accordingly, the volume resistivity is 2.74 ⁇ 10 ⁇ 3 ⁇ ⁇ cm.
  • a transparent conductive film was obtained by the above method.
  • ⁇ Comparative Example 1> (Supporting catalytic metal salt on magnesia) The same operation as in Example 1 was performed to obtain a solid catalyst.
  • volume resistivity of carbon nanotube aggregate The volume resistivity of the carbon nanotube aggregate obtained as described above was measured in the same manner as in Example 1.
  • the carbon nanotube film had a thickness of 105.5 ⁇ m and a surface resistance value of 53.45 ⁇ / ⁇ . Accordingly, the volume resistivity is 5.64 ⁇ 10 ⁇ 1 ⁇ ⁇ cm.
  • volume resistivity of carbon nanotube aggregate The volume resistivity of the carbon nanotube aggregate obtained as described above was measured in the same manner as in Example 1.
  • the carbon nanotube film had a thickness of 65.3 ⁇ m and a surface resistance value of 5.89 ⁇ / ⁇ . Therefore, the volume resistivity is 3.85 ⁇ 10 ⁇ 2 ⁇ ⁇ cm.
  • an aggregate of double-walled carbon nanotubes having a low volume resistivity, high quality, and good dispersibility can be obtained.
  • the molded product, composition and conductive composite obtained from the carbon nanotube aggregate of the present invention exhibit good performance.

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Abstract

L'invention concerne un ensemble de nanotubes de carbone qui satisfait toutes les conditions (1) à (4) suivantes : (1) l'ensemble de nanotubes de carbone a une résistivité en volume non inférieure à 1 × 10-4 Ω·cm mais non supérieure à 1 × 10-2 Ω·cm, (2) pas moins de 50 % des nanotubes de carbone de l'ensemble de nanotubes de carbone sont des nanotubes de carbone à double paroi, (3) l'ensemble de nanotubes de carbone a un rapport Raman G/D non inférieur à 30 mais non supérieur à 200 à une longueur d'onde de mesure de 532 nm et (4) l'ensemble de nanotubes de carbone présente une température de pic de combustion non inférieure à 550˚C mais non supérieure à 700˚C. On peut ainsi obtenir un ensemble de nanotubes de carbone à double paroi qui présente une faible résistivité en volume, une haute qualité et une bonne dispersibilité.
PCT/JP2009/061675 2008-06-27 2009-06-26 Ensemble de nanotubes de carbone et procédé pour leur fabrication WO2009157529A1 (fr)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010101205A1 (fr) * 2009-03-04 2010-09-10 東レ株式会社 Composition contenant des nanotubes de carbone, catalyseur pour la production de nanotubes de carbone, et dispersion aqueuse de nanotubes de carbone
JP2010254546A (ja) * 2009-03-31 2010-11-11 Toray Ind Inc カーボンナノチューブ水性分散液、導電性複合体およびその製造方法
WO2014084042A1 (fr) * 2012-11-28 2014-06-05 東レ株式会社 Complexe contenant des nanotubes de carbone à double paroi
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JP2018535131A (ja) * 2015-09-14 2018-11-29 リンテック オブ アメリカ インコーポレーテッドＬｉｎｔｅｃ ｏｆ Ａｍｅｒｉｃａ， Ｉｎｃ． 形状適応性複数層複合材
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