Method for manufacturing a CNT product

Abstract

To inhibit a non-uniform residue of a CNT on a basal plate when removing or pulling out the CNT having grown on the basal plate from the basal plate.SOLUTION: A method for producing a CNT product includes a CNT synthetic process using a chemical vapor deposition method including: a growth process of supplying a raw material gas to a reaction chamber including a basal plate and making a CNT grow on the basal plate under a growth temperature and a growth pressure; a discharge process of discharging the raw material gas and reducing a pressure of the raw material gas to a reduction pressure being 5% to 95% of the growth pressure; and a holding process of holding the pressure of the raw material gas within a range of the reduction pressure for a prescribed duration.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing CNT products.

Background Art

[0002] Carbon nanotubes (hereinafter sometimes referred to as "CNT") are expected to be used in various applications in a wide range of fields because they are excellent in thermal conductivity, electrical conductivity, mechanical strength, etc.

[0003] Examples of the CNT synthesis process include the arc discharge method, the laser evaporation method, and the chemical vapor deposition method (hereinafter sometimes referred to as the "CVD method"). Among these, since the CVD method is suitable for mass production, the CVD method is mainly used industrially. The production of CNT by the CVD method involves reacting a gas containing carbon atoms as a raw material in the presence of a catalyst to grow CNT. In Patent Document 1, in the CVD method, a synthesis process of CNT having an amorphous layer with a sufficient thickness and capable of suppressing aggregation is disclosed by supplying a raw material gas at a first temperature and supplying a second temperature raw material gas 50 to 200 °C higher than the first temperature.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When using the CVD method for the CNT synthesis process, depending on the adhesion between the substrate and the CNTs grown on the substrate, the inventors of the present application have found that after peeling the CNTs grown on the substrate from the substrate or pulling them out (as a CNT web), CNTs remain unevenly on the substrate. Such uneven remaining of CNTs is a problem from the perspective of CNT productivity. In addition, the uneven remaining of CNTs can impair the uniformity and continuity of the CNTs obtained by peeling or pulling out, and the density of the CNT peeling surface, so it can also be a problem from the perspective of the properties of CNTs (for example, reliability, thermal conductivity, electrical conductivity, etc.).

Means for Solving the Problems

[0006] This disclosure has been made in view of such circumstances. Instead of dealing with it along the extension line of the prior art, an attempt is made to achieve the above object by dealing with it in a new direction, and it has been found that the above main object can be achieved, leading to this disclosure. A preferred embodiment in this disclosure is as follows: [Item 1] A growth step of supplying a source gas to a reaction chamber including a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; An exhaust step of exhausting the source gas and reducing the source gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the source gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, including a CNT synthesis process using a chemical vapor deposition method, including the above steps. [Item 2] The method for manufacturing a CNT product according to Item 1, wherein the growth temperature is maintained in the holding step. [Item 3] The method for manufacturing a CNT product according to Item 1 or 2, using a halide of a transition metal element as a reaction catalyst. [Item 4] The method for manufacturing a CNT product according to any one of Items 1 to 3, wherein at least one second gas selected from the group consisting of a hydrocarbon having an oxygen atom and hydrogen is supplied simultaneously with the supply of the source gas. [Item 5] The method for manufacturing a CNT product according to any one of items 1 to 4, wherein in the growth process, the growth temperature is 500°C or higher and the raw material gas pressure is 1 Torr or higher. [Item 6] The method for manufacturing a CNT product according to any one of items 1 to 5, wherein the reduced pressure is 30% or more and 80% or less of the growth pressure. [Item 7] The method for manufacturing a CNT product according to any one of items 1 to 6, including a temperature reduction process of reducing the reaction chamber atmosphere temperature after the holding process. [Item 8] The method for manufacturing a CNT product according to any one of items 1 to 7, including a second discharge process of discharging the raw material gas after the holding process to make the raw material gas pressure 0.1 Torr or less. [Item 9] The method for manufacturing a CNT product according to any one of items 1 to 8, wherein the second discharge process is performed simultaneously with the temperature reduction process. [Item 10] The method for manufacturing a CNT product according to any one of items 1 to 9, including a CNT array manufacturing process including a peeling process of peeling the CNT grown on the substrate from the substrate. [Item 11] The method for manufacturing a CNT product according to any one of items 1 to 9, including a CNT fiber product manufacturing process including a pulling process of pulling the CNT grown on the substrate out of the substrate as a CNT web. [Item 12] The method for manufacturing a CNT product according to any one of items 1 to 11, wherein CNT is grown on both sides of the substrate. [Item 13] The method for manufacturing a CNT product according to any one of items 1 to 12, using a substrate polished on both sides as the substrate. [Item 14] The method for manufacturing a CNT product according to any one of items 1 to 13, wherein the reaction chamber includes a plurality of the substrates, and the distance between the plurality of substrates is minimized within a range where the CNT grown from each substrate does not contact. [Item 15] A CNT product which is an aggregate of CNTs, wherein a plurality of CNT ends among the CNTs form a tapered structure in which the ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point to the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less. [Item 16] The CNT product according to Item 15, which is a CNT array that is an oriented aggregate of CNTs, wherein a plurality of CNT ends on one surface form a tapered structure in which the ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point to the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less. [Item 17] The CNT product according to Item 15 or 16, wherein the CNT product is a CNT fiber product containing CNTs as fibers, and a plurality of CNT ends form a tapered structure in which the ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point to the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less. [Item 18] The CNT product according to Item 17, which is a CNT web, a CNT yarn, a CNT sheet, a CNT sheet, a CNT woven or knitted fabric, or a CNT non-woven fabric. [Item 19] The CNT product according to any one of Items 15 to 18, wherein a plurality of CNT ends among the CNTs form a repeatedly uneven surface in the length direction of the CNT. [Item 20] The CNT product according to any one of Items 15 to 19, wherein a plurality of CNT ends have a crimped shape. [Item 21] The CNT product according to any one of Items 15 to 20, wherein a plurality of CNT ends form an entangled structure together with neighboring CNT ends. [Item 22] A CNT resin composite obtained by impregnating a CNT product according to any one of Items 15 to 21 with a resin. [Item 23] An article containing a CNT product according to any one of Items 15 to 21 or a CNT resin composite according to Item 22. [Item 24] The article according to Item 23 selected from the group consisting of a heat dissipation material, a heater, and an electromagnetic wave absorption sheet.

Effect of the Invention

[0007] According to the present disclosure, the peelability and drawability of CNTs grown on a substrate from the substrate can be improved, and uneven remaining of CNTs on the substrate after peeling or drawing the CNTs from the substrate can be suppressed. Thereby, the productivity of CNT products can be improved. Further, thereby, the characteristics of CNTs (for example, reliability, thermal conductivity, electrical conductivity, etc.) can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5

Mode for Carrying Out the Invention

[0009] <Method for Manufacturing CNT Products> The manufacturing method of the CNT product in the present disclosure includes the CNT synthesis process described in detail below. The "CNT product" is a product composed of CNTs, and examples thereof include CNTs, CNT aggregates, CNTs bonded to a substrate, CNT arrays, and CNT fiber products. The CNT product may be a CNT oriented aggregate. The "CNT oriented aggregate" is an aggregate of CNTs in which each CNT constituting the CNT oriented aggregate is oriented in a certain direction. Examples of the CNT oriented aggregate include CNT arrays and CNT sheets. The CNT oriented aggregate has anisotropic heat conduction characteristics. That is, it exhibits a high thermal conductivity in the length direction of the CNT and a relatively low thermal conductivity in the direction perpendicular to the length direction of the CNT (the diameter direction of the CNT) (see FIGS. 1 and 2). This anisotropic heat conduction characteristic is useful, for example, for applications as a heat dissipation material.

[0010] [CVD method] In the CNT synthesis process in the present disclosure, the CVD method is used. The CVD method is a kind of deposition method and is so called because a chemical reaction is used in the process of forming a deposit. The CVD method includes a thermal CVD method in which the temperature is raised to decompose the raw material by heat, a photo-CVD method in which light is irradiated to promote a chemical reaction, a plasma CVD method in which a gas is excited to a plasma state, etc. Usually, in the CNT synthesis process in the present disclosure, the thermal CVD method is preferred. Examples of the thermal CVD method include the DIPS method, the CoMoCAT method, the HiPCO method, the supergrowth CVD method, the solid-phase catalyst method, the gas-phase catalyst method, etc.

[0011] [CVD apparatus] In the CNT synthesis process in the present disclosure, a CVD apparatus is used. The CVD apparatus in the present disclosure is not particularly limited, but it may be a hot-wall type that heats the entire reaction chamber or a cold-wall type that heats only the substrate stage and cools the reaction chamber. It may be horizontal or vertical (excellent in temperature distribution, response speed, gas flow control, etc.), and may be a batch process (processing multiple sheets simultaneously), a single-wafer process (processing one by one), or a continuous process type (conveyor type). From the viewpoint of being suitable for mass production, the continuous process type is preferred.

[0012] The CVD apparatus may include a reaction chamber containing a substrate, a gas introduction means for introducing a gas (source gas or carrier gas) into the reaction chamber, an exhaust means for exhausting a gas (unreacted source gas, source decomposition gas, or carrier gas) from the reaction chamber, and a heater.

[0013] [Substrate and Catalyst] The substrate serves as a base for growing CNTs. The substrate has a melting point equal to or higher than the growth temperature. As the type of substrate, a semiconductor substrate such as a silicon substrate, an insulating substrate such as an alumina (sapphire) substrate, a MgO substrate, or a glass substrate, a metal substrate, etc. can be used. Further, those with a thin film formed on these substrates may also be used. For example, those with an oxide film (e.g., silicon oxide film) having a thickness of about 10 nm to 1000 nm (e.g., 100 nm to 500 nm) formed on a silicon substrate can be used.

[0014] A plurality of substrates may be included in the reaction chamber. The number of substrates included in the reaction chamber may be 5 or more, 10 or more, or 30 or more. The number of substrates included in the reaction chamber may be 500 or less, 250 or less, or 50 or less. When a plurality of substrates are included in the reaction chamber, the distance between the plurality of substrates is preferably minimized within a range where the CNTs grown from each substrate do not contact each other. Thereby, no extra space is generated in the reaction chamber, so that the maximum number of substrates can be arranged in the reaction chamber, and the productivity of CNTs can be improved.

[0015] CNTs may be grown from one side of the substrate, but growing CNTs from both sides of the substrate is preferable from the viewpoint of improving the productivity of CNTs.

[0016] A polished substrate may be used as the substrate. By using a polished substrate, the growth property of CNTs can be enhanced. Only one side of the substrate may be polished, but it is preferable that both sides of the substrate are polished from the viewpoint of improving the productivity of CNTs.

[0017] The substrate may have a support for the catalyst, such as Mo, Ti, Hf, Zr, Nb, V, TaN, TiSi x (for example, x = 1 to 2), Al, Al2O3, TiO x (for example, x = 1 to 2), Ta, W, Cu, Au, Pt, Pd, TiN, or a support containing at least one of these. The support may have a thickness of 0.1 nm or more, 0.5 nm or more, or 1 nm or more, and may be 10 nm or less, 7.5 nm or less, or 5 nm or less. A laminated structure may be formed by the support layer and the catalyst layer, or the catalyst may be dispersed and present in the support.

[0018] Preferably, the substrate has a catalyst layer having a catalyst function on its surface. The catalyst layer can be formed, for example, by attaching catalyst particles by sputtering. At this time, from the viewpoint of the growth property of CNTs, it is preferable to alternately form portions where catalyst particles are attached and portions where they are not attached. Such an island-shaped catalyst layer can be produced, for example, by installing a mesh on the substrate and attaching catalyst particles in a certain pattern by sputtering from above, or by controlling the size of the catalyst particles in advance using a differential electrostatic classifier. The catalyst layer may have a thickness of 0.1 nm or more, 0.5 nm or more, or 1 nm or more, and may be 10 nm or less, 7.5 nm or less, or 5 nm or less. The island-shaped catalyst layer may have a diameter of 0.1 nm or more, 0.5 nm or more, 1 nm or more, or 3 nm or more, and may be 15 nm or less, 10 nm or less, 7.5 nm or less, or 5 nm or less.

[0019] The type of catalyst used in the growth reaction of CNTs is not limited, but it preferably contains transition metal elements of Groups 3 to 12 such as V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, W, Ag, Au, Pt, etc. The catalyst may be a halide (e.g., fluoride, chloride, bromide, and iodide) or an oxide of these elements. From the perspective of the growth rate, the catalyst may be a halide, and it is particularly preferable to use iron halide. More specifically, examples of the halide include iron fluoride, cobalt fluoride, nickel fluoride, iron chloride, cobalt chloride, nickel chloride, iron bromide, cobalt bromide, nickel bromide, iron iodide, cobalt iodide, nickel iodide, etc. Here, the halide may be divalent, trivalent, or polyvalent, such as iron(II) chloride and iron(III) chloride.

[0020] A sublimable catalyst (e.g., iron chloride) may be present in the reaction chamber as a gas-phase catalyst. The method for introducing the gas-phase catalyst into the reaction chamber is not limited. A gas-phase catalyst supply unit may be provided in the reaction chamber and supplied therefrom, or a material (catalyst source) in a physical state other than gas (typically a solid state) that provides the gas-phase catalyst inside the reaction chamber may be installed, and the inside of the reaction chamber may be heated and / or depressurized to generate the gas-phase catalyst from the catalyst source and make the gas-phase catalyst present inside the reaction chamber. Alternatively, a catalyst generation reaction may occur inside the reaction chamber. For example, in the case of iron chloride, an iron-group element-containing material such as a lump, flat plate, steel wool, or powdered iron is set at a predetermined temperature inside the reaction chamber, and a halogen-containing substance that reacts with the iron-group element-containing material inside the reaction chamber is supplied to generate a gas-phase catalyst. A specific example of generating a gas-phase catalyst using a catalyst source is as follows: When anhydrous iron(II) chloride is placed as a catalyst source inside the reaction chamber, and the inside of the reaction chamber is heated and depressurized to sublime anhydrous iron(II) chloride, a gas-phase catalyst composed of vapor of iron(II) chloride can be made to exist inside the reaction chamber.

[0021] [Each step of the CNT synthesis process] The manufacturing method of the CNT product in the present disclosure includes the synthesis process of CNTs. The synthesis process of CNTs includes a growth step, an exhaust step, and a holding step. The synthesis process of CNTs in the present disclosure may further include a temperature reduction step, a second exhaust step, and other steps.

[0022] (Growth step) The synthesis process in the present disclosure includes a growth step. The growth step includes supplying a raw material gas into a reaction chamber including a substrate, and growing CNTs on the substrate under a growth temperature and a growth pressure. Before heating the substrate to the growth temperature, the atmosphere in the reaction chamber may be vacuum or may be replaced with a carrier gas. When supplying the raw material gas into the reaction chamber, the atmosphere in the reaction chamber may be heated to a predetermined temperature (growth temperature). Here, the "growth temperature" is the reaction chamber atmosphere temperature at which the growth reaction of CNTs can proceed, and the "growth pressure" is the reaction chamber pressure of the raw material gas at which the growth reaction of CNTs can proceed.

[0023] The raw material gas is a gaseous compound that becomes the carbon raw material of CNTs. The number of carbon atoms in the raw material gas may be 1 or more, 2 or more, or 3 or more, and may be 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or 1 or less, preferably 3 or less. The raw material gas may be a hydrocarbon. Examples of the raw material gas include aliphatic saturated hydrocarbons such as methane, ethane, propane, butane, and hexane, aliphatic unsaturated hydrocarbons such as ethylene, propylene, butene, isobutene, and acetylene, aromatic hydrocarbons such as benzene, toluene, xylene, and naphthalene, alcohols such as methanol and ethanol, mixtures thereof, etc., and typically acetylene.

[0024] A second gas may be supplied into the reaction chamber simultaneously with the raw material gas. The second gas is a gas different from the raw material gas and is a hydrocarbon having an oxygen atom 、 hydrogen , and carbon monoxide and is at least one gas selected from the group consisting of. The second gas may have an etching effect on the catalyst. Also, the second gas may be a reducing substance.

[0025] The hydrocarbon having an oxygen atom may be a hydrocarbon having alcoholic oxygen, a hydrocarbon having carbonyl oxygen, or a hydrocarbon having ether oxygen, preferably a hydrocarbon having alcoholic oxygen or a hydrocarbon having carbonyl oxygen, particularly a hydrocarbon having carbonyl oxygen. The number of carbon atoms of the hydrocarbon having an oxygen atom may be 1 or more, 2 or more, or 3 or more, and may be 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or 1 or less, preferably 3 or less.

[0026] Specific examples of the second gas include carbon monoxide, acetone, ethanol, methanol, hydrogen, etc. Preferred specific examples include carbon monoxide, acetone, and hydrogen, particularly carbon monoxide and acetone.

[0027] By supplying the second gas simultaneously with the raw material gas, it may have the effect of enhancing the growth property of CNTs and further improving the spinnability of the produced CNTs. In addition, it can exhibit effects such as a decrease in the activation energy of the reaction related to the growth of the CNT array, an improvement in the growth rate of the CNT array, an improvement in the growth stability of the CNT array, a prolongation of the life of the gas-phase catalyst by removing amorphous carbon as the deactivation cause, and an improvement in the uniformity of the growth length.

[0028] In order to supply the second gas, in addition to or instead of supplying the second gas itself, a raw material capable of forming the second gas can also be supplied. For example, in order to supply carbon monoxide as the second gas, in addition to or instead of supplying the above-mentioned carbon monoxide itself, a raw material capable of forming carbon monoxide can also be supplied. Examples of the raw material capable of forming carbon monoxide include carbon dioxide, carbonyl complexes, etc. These raw materials can form (generate) carbon monoxide in the reaction chamber and exhibit the same effects as when carbon monoxide is supplied.

[0029] The raw material gas pressure in the growth process may be 1 Torr or more, 3 Torr or more, 5 Torr or more, 10 Torr or more, 25 Torr or more, or 50 Torr or more, and is preferably 1 Torr or more. The raw material gas pressure in the growth process may be 300 Torr or less, 200 Torr or less, 150 Torr or less, 100 Torr or less, 50 Torr or less, 25 Torr or less, or 12.5 Torr or less, and is preferably 100 Torr or less.

[0030] The ratio of the second gas pressure to the raw material gas pressure (second gas pressure / raw material gas pressure) in the growth process may be 0.1% or more, 1% or more, 2% or more, 3% or more, 5% or more, 10% or more, or 20% or more, and is preferably 1% or more. In the growth process The second gas pressure ratio with respect to the raw material gas pressure (second gas pressure / raw material gas pressure) may be 500% or less, 300% or less, 100% or less, 50% or less, 30% or less, 20% or less, 10% or less, or 5% or less, and is preferably 30% or less.

[0031] A carrier gas may be supplied into the reaction chamber simultaneously with the raw material gas. Examples of the carrier gas include noble gases such as argon, helium, or neon, and nitrogen. The amount of the carrier gas may be appropriately determined, and for example, it may be 100% or more and 10000% or less of the raw material gas pressure. In addition, if necessary, other gases such as hydrogen and water vapor may be supplied into the reaction chamber within a range that does not impair the effects of the present invention.

[0032] The growth temperature may be a temperature at which the raw material gas reacts to grow CNTs on the substrate. For example, it may be 500 °C or more, 550 °C or more, 600 °C or more, 650 °C or more, 700 °C or more, 750 °C or more, 800 °C or more, or 850 °C or more, and is preferably 600 °C or more. The growth temperature may be 1100 °C or less, 1050 °C or less, 1000 °C or less, 950 °C or less, 900 °C or less, or 850 °C or less, and is preferably 1000 °C or less.

[0033] The time of the growth process may be determined by the desired length of the CNT. If short CNTs are required, the time of the growth process may be shortened, and if long CNTs are required, the time of the growth process may be lengthened.

[0034] (Exhaust process) The synthesis process in the present disclosure further includes an exhaust process. The exhaust process includes stopping the supply of the raw material gas and discharging the raw material gas to reduce the raw material gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure.

[0035] The reduced pressure may be 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, or 60% or more of the raw material gas pressure in the growth process, preferably 30% or more or 50% or more. The reduced pressure may be 95% or less, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, or 40% or less of the raw material gas pressure in the growth process, preferably 80% or less.

[0036] The time of the exhaust process may be 0.01 seconds or more, 0.1 seconds or more, 1 second or more, or 10 seconds or more. The time of the exhaust process may be 300 seconds or less, 200 seconds or less, 100 seconds or less, 60 seconds or less, or 30 seconds or less, for example, 25 seconds or less, within 20 seconds, within 15 seconds, within 10 seconds, or within 5 seconds.

[0037] (Holding process) The synthesis process in the present disclosure further includes a holding process. The holding process holds the raw material gas pressure within the range of the reduced pressure for a predetermined time. During the holding process, it is preferable that the raw material gas pressure is kept constant. During the holding process, in order to hold the pressure, the supply of gas into the reaction chamber and the discharge of gas from the reaction chamber may be blocked.

[0038] The time of the holding process may be a predetermined time, for example, 5 seconds or more, 10 seconds or more, 20 seconds or more, 30 seconds or more, 40 seconds or more, 50 seconds or more, or 60 seconds or more. The time of the holding process may be 300 seconds or less, 250 seconds or less, 200 seconds or less, 150 seconds or less, 100 seconds or less, or 50 seconds or less.

[0039] In the holding step, the reaction chamber ambient temperature may be held within a certain range, preferably held at the growth temperature. During the holding step, the reaction chamber ambient temperature may be held constant.

[0040] (Cooling step) The synthesis process according to the present disclosure may further include a cooling step. The cooling step is performed after the holding step and includes lowering the reaction chamber ambient temperature.

[0041] The cooling rate of the reaction chamber ambient temperature may be 3 °C / min or more, 5 °C / min or more, 7 °C / min or more, 9 °C / min or more, or 12 °C / min or more. The cooling rate of the reaction chamber ambient temperature may be 50 °C / min or less, 40 °C / min or less, 30 °C / min or less, or 20 °C / min or less.

[0042] The cooling step may be performed until the reaction chamber ambient temperature reaches a temperature at which the CNTs are not oxidized by oxygen in the air, for example, less than 500 °C, 400 °C or less, or 300 °C or less. Once the reaction chamber ambient temperature reaches a temperature at which the CNTs are not oxidized by oxygen in the air, the substrate may be released to atmospheric pressure.

[0043] (Second exhaust step) The synthesis process according to the present disclosure may further include a second exhaust step. The second exhaust step is performed after the holding step and discharges the raw material gas to further reduce the raw material gas pressure from the reduced pressure.

[0044] The raw material gas pressure after the second exhaust step is not particularly limited, but may be 0 Torr or more, 0.0001 Torr or more, 0.001% or more of the reduced pressure, or 0.01% or more of the reduced pressure. The raw material gas pressure after the second exhaust step may be 0.1 Torr or less, 0.08 Torr or less, 0.05 Torr or less, 0.03 Torr or less, or 0.01 Torr or less, preferably 0.05 Torr or less. The raw material gas pressure after the second exhaust step may be 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 1% or less of the reduced pressure, preferably 10% or less.

[0045] The lower limit of the time of the second discharging step is not particularly limited, and may be 0.01 seconds or more, 0.1 seconds or more, 1 second or more, or 10 seconds or more. The time of the second discharging step may be 300 seconds or less, 200 seconds or less, 100 seconds or less, 60 seconds or less, or 30 seconds or less, and for example, 25 seconds or less, within 20 seconds, within 15 seconds, within 10 seconds, or within 5 seconds.

[0046] The second discharging step may be performed simultaneously with the temperature lowering step. In addition, when the desired raw material gas pressure has been reached but the desired reaction chamber ambient temperature has not been reached, the temperature lowering step may be continued even after the second discharging step.

[0047] [Structure of CNT] The CNT obtained by the synthesis process of the present disclosure may be single-layer or multi-layer, but is preferably multi-layer. The diameter of the CNT may be 0.5 nm or more, 3 nm or more, 5 nm or more, 10 nm or more, 30 nm or more, 50 nm or more, or 100 nm or more, preferably 5 nm or more, more preferably 10 nm or more. The diameter of the CNT may be 500 nm or less, 300 nm or less, 100 nm or less, 80 nm or less, 60 nm or less, 40 nm or less, or 20 nm or less, preferably 100 nm or less. The number of layers of the CNT may be 1 or more, 2 or more, 3 or more, 5 or more, 7 or more, 10 or more, or 20 or more, preferably 2 or more. The number of layers of the CNT may be 55 or less, 45 or less, 35 or less, 25 or less, 15 or less, or 5 or less. The diameter and the number of layers of the CNT can be determined by the type of catalyst, the size of catalyst particles, etc.

[0048] The length of the CNTs obtained by the synthesis process of the present disclosure is preferably relatively long. The average length of the CNTs may be 0.05 mm or more, 0.1 mm or more, 0.2 mm or more, 0.4 mm or more, 0.6 mm or more, 1.0 mm or more, 3.0 mm or more, 5 mm or more, 10 mm or more, preferably 0.1 mm or more, and more preferably 0.4 mm or more. The average length of the CNTs may be 200 mm or less, 150 mm or less, 100 mm or less, 50 mm or less, 25 mm or less, 10 mm or less, 5.0 mm or less, preferably 25 mm or less. The length of the CNTs is determined by the time of the growth process. When short CNTs are required, the time of the growth process may be shortened, and when long CNTs are required, the time of the growth process may be lengthened. The average length of the CNTs can be determined, for example, from SEM photographs.

[0049] The G / D ratio of the CNTs obtained by the synthesis process of the present disclosure may be 1 or more, 1.5 or more, 2 or more, 2.5 or more, preferably 2 or more. The G / D ratio of the CNTs obtained by the synthesis process of the present disclosure may be 10 or less, 8 or less, 6 or less, or 4 or less. The G / D ratio is an index of the crystallinity of carbon nanotubes determined by Raman spectroscopy.

[0050] The purity of the CNTs obtained by the synthesis process of the present disclosure may be 80% or more, 85% or more, 90% or more, 95% or more, 98% or more, or 99% or more, preferably 95% or more. The purity of the CNTs can be determined, for example, by elemental analysis using X-ray fluorescence.

[0051] The CNTs obtained by the synthesis process of the present disclosure have a specific structure at the CNT ends on one side (substrate side surface).

[0052] In this specification, the "CNT end" may refer to a distance of 10000 nm or less, 9000 nm or less, 8000 nm or less, 7000 nm or less, 6000 nm or less, 5000 nm or less, 4000 nm or less, 3000 nm or less, 2000 nm or less, 1000 nm or less, or 750 nm or less from the terminal point (the outermost end point) of the CNT.

[0053] [Manufacturing Process of CNT Array] In the present specification, the "CNT array" refers to an oriented aggregate of CNTs grown from a substrate (also referred to as a CNT forest) that is separated from the substrate. Since it has undergone the above synthesis process, the CNT array in the present disclosure has a specific structure at a plurality of CNT ends on one side thereof (the side surface of the substrate (the surface that was bonded to the substrate before peeling the CNTs from the substrate)).

[0054] The manufacturing process of the CNT array in the present disclosure further includes a peeling step after the above CNT synthesis process. In the peeling step, the CNTs grown on the substrate are peeled from the substrate to obtain a CNT array. The CNTs grown on the substrate as used herein are a vertically oriented CNT aggregate (so-called CNT forest) on the substrate. In the present specification, the vertically oriented CNT aggregate peeled and isolated is referred to as a CNT array in the present specification. FIG. 1 shows a schematic diagram of the manufacturing process of the CNT array.

[0055] The method of peeling CNTs from the substrate in the peeling step may be a physical, chemical, or mechanical peeling method. Specifically, for example, methods of peeling using an electric field, a magnetic field, a centrifugal force, a surface tension, etc., a method of mechanically peeling from the substrate, and a method of peeling from the substrate using pressure or heat can be exemplified. It is also possible to suck the CNTs using a vacuum pump and peel them off from the substrate. Examples of the method of mechanically peeling from the substrate include a method of directly picking up the CNTs with tweezers and peeling them from the substrate, and a method of peeling the CNTs from the substrate using a thin blade such as a plastic spatula or a cutter blade having a sharp part.

[0056] (Structure of CNT Ends in CNT Array) In the CNT array, it is preferable that a plurality of CNT ends have a structure in which the ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point and the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less.

[0057] In the CNT array, the CNT ends having a structure where D1 / D2 is 0.75 or less may be 25% or more of the CNT ends on one surface, for example, 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more. In the CNT array, the CNT ends having a structure where D1 / D2 is 0.75 or less may be 75% or less, 50% or less, or 25% or less of the CNT ends on one surface.

[0058] In the CNT array, D1 / D2 may be 0.75 or less, 0.6 or less, 0.45 or less, or 0.30 or less. In the CNT array, D1 / D2 may be 0.10 or more, 0.20 or less, 0.30 or more, 0.35 or more, or 0.40 or more.

[0059] It is preferable that a plurality of CNT ends in the CNT array form a repeating uneven surface in the length direction of the CNT. The repeating uneven surface is also referred to as a wavy surface, a corrugated surface, or a zigzag surface. The repeating uneven surface is caused by the CNT array forming a structure called a dumpling-like structure, a nodular structure, a bellows structure, or a twist structure.

[0060] The CNT ends forming the repeating uneven surface in the CNT array may be 25% or more of the CNT ends on one surface, for example, 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more. The CNTs forming the repeating uneven surface in the CNT array may be 75% or less, 50% or less, or 25% or less of the CNT ends on one surface. Here, the CNT end may refer to a point within 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less from the end point of the CNT.

[0061] The number of irregularities on the repeating uneven surface of the CNT ends in the CNT array may be 5 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 60 or more per μm in the length direction of the CNT. The number of irregularities on the repeating uneven surface in the CNT array may be 100 or less, 80 or less, 60 or less, 40 or less, 30 or less, or 20 or less per μm in the length direction of the CNT.

[0062] It is preferable that a plurality of CNT ends in the CNT array have a crimped shape. Crimping is also referred to as curling. The type of crimping is not particularly limited, and may be, for example, a zigzag type, a waveform / omega type, or a spiral type. By crimping, these CNTs may form an entangled structure together with the adjacent CNT ends. Here, the CNT end may refer to a distance of 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less from the end point of the CNT.

[0063] The CNT ends having a crimped shape in the CNT array may be 25% or more of the CNT ends on one surface, and may be, for example, 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more. The CNTs having a crimped shape in the CNT array may be 75% or less, 50% or less, or 25% or less of the CNT ends on one surface.

[0064] In the CNT array, the number of crimps (the number of peaks per unit length) at the CNT ends may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more per μm. In the CNT array, the number of crimps (the number of peaks per unit length) may be 20 or less, 15 or less, 10 or less, 7 or less, or 5 or less per μm.

[0065] [Manufacturing Process of CNT Fiber Products] In the present disclosure, the "CNT fiber product" is a fiber product containing CNTs as fibers. The CNT fiber product in the present disclosure contains CNTs obtained by the above-described synthesis process. Specifically, examples of the CNT fiber product include a CNT web, a CNT yarn, a CNT sheet, a CNT woven or knitted fabric, a CNT nonwoven fabric, and the like. Since it has undergone the above synthesis process, the CNT ends of the CNTs contained as fibers in the CNT fiber product in the present disclosure have a specific structure.

[0066] In the manufacturing process of CNT fiber products, it is preferable to include a drawing step of drawing out the CNT grown on the above-mentioned substrate as a CNT web from the substrate to obtain a CNT fiber product. The drawing step may utilize the dry spinning phenomenon of CNTs. The "dry spinning phenomenon of CNTs" refers to a phenomenon in which when the end of a CNT aggregate (so-called CNT forest) vertically oriented on a substrate is pinched and pulled along the substrate surface, a CNT web, which is a CNT connected body in which CNTs are spontaneously bonded by van der Waals forces, is formed. By this dry spinning phenomenon of CNTs, the three-dimensionally grown CNT aggregate on the substrate can be changed into an aggregate forming a two-dimensional network. This morphological change is similar to the operation of spinning silk from a silkworm cocoon. However, since CNTs are bonded by strong van der Waals forces, unlike conventional spinning, spinning can be performed without adding twist to the CNT web. By twisting CNT webs together, CNT yarns can be formed, and by laminating CNT webs, CNT sheets can be formed. The manufacturing process of CNT fiber products utilizing the dry spinning phenomenon is known. For example, reference can be made to Y. Inoue, K. Kakihata, Y. Hirono, T. Horie, A. Ishida & H. Mimura : Appl. Phys. Lett., 92, 21 (2008), 213113.; Y. Inoue, Y. Suzuki, Y. Minami, J. Muramatsu, Y. Shimamura, K. Suzuki, A. Ghemes, M. Okada, S. Sakakibara, H. Mimura & K. Naito : Carbon, 49, 7 (2011), 2437-2443., etc. CNT woven fabrics and CNT knitted fabrics can be obtained by weaving or knitting CNTs or CNT yarns as fibers. CNT non-woven fabrics can be obtained, for example, by dispersing CNTs in a dry or wet manner and then bonding them.

[0067] (CNT sheet) The CNT fiber product may be a CNT sheet which is a laminate of CNT webs. Since the CN sheet has anisotropic thermal conductivity, it is suitable as a heat dissipation material. The CNT sheet can be obtained by laminating CNT webs from CNTs synthesized on a substrate by utilizing the dry spinning phenomenon. The lamination of the CNT webs may be performed by using a winding roll. FIG. 2 shows a schematic diagram of the manufacturing process of the CNT sheet.

[0068] The number of laminations in the CNT sheet may be 5 or more, 10 or more, 20 or more, 30 or more, 50 or more, 70 or more, or 100 or more, and the higher the number of laminations, the more excellent the thermal conductivity can be. The number of laminations in the CNT sheet may be 10000 or less, 1000 or less, or 100 or less. At the time of drawing, the CNTs are detached (a kind of peeling) from the substrate, but since the CNTs obtained by the synthesis process of the present disclosure have excellent detachability from the substrate, according to the present disclosure, the remaining of the CNTs on the substrate can be suppressed.

[0069] (Structure of CNT ends in CNT fiber products) In the CNT fiber product, it is preferable that a plurality of CNT ends have a structure in which the ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point and the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less.

[0070] In the CNT fiber product, the CNT ends having a structure in which D1 / D2 is 0.75 or less may be 12.5% or more of the CNT ends, for example, 15% or more, 17.5% or more, 20% or more, 22.5% or more, or 25% or more. In the CNT fiber product, the CNT ends having a structure in which D1 / D2 is 0.75 or less may be 40% or less, 30% or less, or 15% or less of the CNT ends.

[0071] In the CNT fiber product, D1 / D2 may be 0.75 or less, 0.6 or less, 0.45 or less, or 0.30 or less. In the CNT fiber product, D1 / D2 may be 0.10 or more, 0.20 or more, 0.30 or more, 0.35 or more, or 0.40 or more.

[0072] It is preferable that a plurality of CNT ends in the CNT fiber product form a repeating uneven surface in the length direction of the CNT. The repeating uneven surface is also referred to as a wavy surface, a corrugated surface, or a zigzag surface. The repeating uneven surface is caused because the CNT fiber product forms a structure called a dumpling-like structure, a nodular structure, a bellows structure, or a twist structure.

[0073] The CNT ends forming the repeating uneven surface in the CNT fiber product may be 12.5% or more of the CNT ends, for example, 15% or more, 17.5% or more, 20% or more, 22.5% or more, or 25% or more. The CNTs forming the repeating uneven surface in the CNT fiber product may be 40% or less, 30% or less, or 15% or less of the CNT ends. Here, the CNT end may refer to a point within 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less from the end point of the CNT.

[0074] The number of unevennesses in the repeating uneven surface of the CNT ends in the CNT fiber product may be 5 unevennesses / μm or more, 10 unevennesses / μm or more, 20 unevennesses / μm or more, 30 unevennesses / μm or more, 40 unevennesses / μm or more, 50 unevennesses / μm or more, or 60 unevennesses / μm or more in the length direction of the CNT. The number of unevennesses in the repeating uneven surface in the CNT fiber product may be 100 unevennesses / μm or less, 80 unevennesses / μm or less, 60 unevennesses / μm or less, 40 unevennesses / μm or less, 30 or less, or 20 unevennesses / μm or less in the length direction of the CNT.

[0075] It is preferable that a plurality of CNT ends in the CNT fiber product have a crimped (curled) shape. Crimped (curled) also means curled. The type of crimp is not particularly limited, and for example, it may be a zigzag type, a waveform / omega type, or a spiral type. By crimping, these CNTs may form an entangled structure together with neighboring CNT ends. Here, the CNT end may refer to a distance of 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less from the end point of the CNT.

[0076] The CNT ends having a crimped shape in the CNT fiber product may be 12.5% or more of the CNT ends, for example, 15% or more, 17.5% or more, 20% or more, 22.5% or more, or 25% or more. The CNTs having a crimped shape in the CNT fiber product may be 40% or less, 30% or less, or 15% or less of the CNT ends.

[0077] In the CNT fiber product, the number of crimps (the number of peaks per unit length) at the CNT ends may be 1 peak / μm or more, 2 peaks / μm or more, 3 peaks / μm or more, 4 peaks / μm or more, 5 peaks / μm or more, or 6 peaks / μm or more. In the CNT fiber product, the number of crimps (the number of peaks per unit length) may be 20 peaks / μm or less, 15 peaks / μm or less, 10 peaks / μm or less, 7 peaks / μm or less, or 5 peaks / μm or less.

[0078] <CNT resin composite> The CNT resin composite in the present disclosure is obtained by impregnating the above-described CNT product with resin. The CNT resin composite may be obtained by impregnating a CNT oriented aggregate with resin and then curing the resin. Conventionally, a heat dissipation material in which a metal or a carbon filler is compounded with resin has been known, but its thermal conductivity has not been sufficient. Also, if a metal is used as a heat dissipation material, the thermal conductivity increases and heat dissipation becomes easy, but molding is difficult and it is difficult to use for applications where insulation is required. By using the CNT resin composite in the present disclosure, such problems can be solved.

[0079] As a method for manufacturing a CNT resin composite in the present disclosure, for example, a method of impregnating a CNT product with a resin melted by heating and then cooling and curing it, or a method of impregnating CNTs with a liquid resin (e.g., monomer, prepolymer) and then curing (heating curing, photo-curing, etc.) can be used. FIGS. 1 and 2 respectively show a schematic diagram of a process of obtaining a CNT resin composite by combining a CNT array and a resin, and a schematic diagram of a process of obtaining a CNT resin composite by combining a CNT sheet and a resin. The CNT product contained in the CNT resin composite may be a CNT alignment aggregate. By including the CNT alignment aggregate, the CNT resin composite has anisotropic thermal conductivity and can have a higher thermal conductivity in the length direction (growth direction) of the CNTs compared to the diameter direction (direction perpendicular to the growth direction) of the CNTs. And the thermal conductivity of the CNT resin composite is significantly higher compared to the thermal conductivity of the resin alone (1 W / mK or less). Such a unique thermal conductivity of the CNT resin composite is suitable as a heat dissipation material. Also, by using a resin, the moldability is improved, and it is also easy to use for applications where insulation is required.

[0080] [Components of the CNT Resin Composite] (CNT Component) The CNT resin composite includes the above-described CNT product (e.g., a CNT alignment aggregate, e.g., a CNT array or a CNT sheet).

[0081] (Resin Component) The CNT resin composite includes a resin. The resin may be a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include epoxy resins, phenolic resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, urethane resins, thermosetting polyimides, and thermosetting acrylic resins. Examples of thermoplastic resins include polyolefins, polyhalogenated olefins, polystyrene, polyvinyl acetate, polyurethanes, Teflon (registered trademark), ABS resins, AS resins, acrylic resins, polyamides, polyacetals, polycarbonates, polyethers, polyesters, thermoplastic polyimides, polyamide resins, polyamideimide resins, polyester resins, non-curing acrylic resins, and mixtures thereof.

[0082] In the CNT resin composite, the CNT content (the amount occupied by the CNT product) depends on the type of the CNT product to be compounded, but may be 5% by weight or more, 20% by weight or more, 40% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or 85% by weight or more, and preferably 40% by weight or more, 60% by weight or more, or 80% by weight or more. In the CNT resin composite, the CNT content may be 99% by weight or less, 95% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, or 50% by weight or less. The higher the CNT content, the more excellent the thermal conductivity of the CNT resin composite can be.

[0083] (Other components) The CNT resin composite may contain other components as long as the effects of the present invention are not lost. Examples of other components include colorants such as organic dyes and organic pigments; organic fillers such as organic particles and organic fibers; anti-aging agents / antioxidants; ultraviolet absorbers, light stabilizers, and the like.

[0084] [Structure of CNT resin composite] The CNT resin composite may be in the form of a sheet, film, rectangular parallelepiped, or cylindrical shape, etc.

[0085] The size of the CNT resin composite depends on the type of the CNT product to be compounded, but the amount of the resin component may be adjusted so as to be of the same size as the CNT product to be compounded. For example, the amount of the resin component may be reduced to expose the CNT product from the surface, or the amount of the resin component may be increased to design such that the CNT product is not exposed from the surface. For example, the endpoints of a part (for example, 1% or more, 5% or more, 10% or more, or 25% or more, and 75% or less, 50% or less, 25% or less, 10% or less, or 5% or less) of the CNTs may be within the range of ±1.0 mm, ±0.5 mm, ±0.3 mm, ±0.2 mm, ±0.1 mm, or ±0.05 mm from the outer surface of the resin.

[0086] When the CNT product to be compounded is a CNT alignment aggregate, the alignment direction of the CNT alignment aggregate (the growth direction of the CNT) may be a direction along the plane direction of the CNT resin composite, or may be a direction inclined from the plane direction of the CNT resin composite (for example, the inclination angle is 1° or more, 3° or more, 10° or more, 15° or more, or 30° or more, and 45° or less, 30° or less, or 15° or less).

[0087] [Physical properties of CNT resin composite] The thermal conductivity of the CNT resin composite in the length direction of the CNT may be 1 W / mK or more, 3 W / mK or more, 5 W / mK or more, 10 W / mK or more, or 15 W / mK or more. The thermal conductivity of the CNT resin composite in the length direction of the CNT may be 100000 W / mK or less, 10000 W / mK or less, 1000 W / mK or less, or 1000 W / mK or less.

[0088] The thermal conductivity of the CNT resin composite in the diameter direction of the CNT may be 0.3 W / mK or more, 1 W / mK or more, 2 W / mK or more, 3 W / mK or more, or 5 W / mK or more. The thermal conductivity of the CNT resin composite with respect to the diameter direction may be 50000 W / mK or less, 5000 W / mK or less, or 500 or less.

[0089] The thermal conductivity of the CNT in the length direction in the CNT resin composite may be 1.2 times or more, 1.5 times or more, 2.0 times or more, 2.5 times or more, 3.0 times or more, 3.5 times or more, or 4.0 times or more the thermal conductivity of the CNT in the diameter direction in the CNT resin composite, preferably 2 times or more. The thermal conductivity of the CNT in the length direction in the CNT resin composite may be 50 times or less, 25 times or less, or 10 times or less the thermal conductivity of the CNT in the diameter direction in the CNT resin composite.

[0090] <Article> The articles in the present disclosure include the above-described CNT products or the above-described CNT resin composites. The CNT products and the CNT resin composites can be applied to various articles by taking advantage of their thermal conductivity, electrical conductivity, insulation properties, mechanical properties, etc. There is a wide variety of articles including the CNT products and the CNT resin composites. For example, examples of the articles include heat dissipation materials, heaters, stretchable sheet-like strain sensors, electrode sheets, battery components, electronic components, automobiles, airplanes, building materials, electromagnetic wave absorption sheets, and the like.

Examples

[0091] Hereinafter, the present invention will be described more specifically by showing examples and comparative examples, but the present invention is not limited by these examples.

[0092] [CNT Synthesis Example 1] A thermal CVD apparatus including a reaction chamber (volume 38 L) containing a substrate, a gas introduction section, and a gas discharge section was used. A Si substrate with a thermal oxide film having a diameter of 4 inches was used as the substrate. As the catalyst, iron(II) chloride was heated above its sublimation temperature, and fine particles of iron(II) chloride were deposited on the substrate. The obtained substrate was placed in the reaction chamber of the CVD apparatus. CNTs were grown on the substrate for 10 to 30 minutes under the conditions of a temperature (about 800 °C), an acetylene gas flow rate (about 10 L / min), a carbon monoxide flow rate (1 L / min or less), and a reaction chamber gas pressure (about 5 Torr). At the time when 10 to 30 minutes had elapsed, the reaction chamber gas pressure was reduced by about 2 Torr from the pressure during growth, and it was held for about 40 seconds while maintaining the growth temperature. Then, the reaction chamber gas pressure was reduced to substantially 0 Torr in about 20 seconds, the temperature was decreased to 300 °C or less at 15 to 20 °C / min, and the atmosphere was released. As a result, CNTs (multi-layer, length about 0.5 to 1.5 mm, diameter about 40 to 60 nm, G / D ratio about 2.5 to 3, purity 99% or more) grown substantially perpendicular to the substrate surface were obtained. The length and the diameter were determined from SEM photographs. The G / D ratio was determined by Raman analysis. The purity was determined by thermogravimetric analysis.

[0093] [Comparative CNT Synthesis Example 1] When 10 to 30 minutes had passed since the start of CNT growth, the gas was discharged to rapidly reduce the reaction chamber gas pressure to approximately 0 Torr, and the temperature was decreased to 300 °C or lower at a rate of 15 to 20 °C per minute and then the chamber was opened to the atmosphere. CNTs were synthesized in the same manner as in CNT Synthesis Example 1, except for the above operations. As a result, CNTs that grew almost perpendicular to the substrate surface were obtained.

[0094] [Production Example 1 of CNT Array] The CNTs grown from the substrate after synthesis in CNT Synthesis Example 1 were peeled off using a resin spatula having a sharp edge to obtain a CNT array. An SEM photograph of the CNT ends on the substrate side of the obtained CNT array is shown in Fig. 3A. Also, an SEM photograph of the substrate after CNT peeling is shown in Fig. 4A. It was almost confirmed that there was little CNT remaining on the substrate after peeling, and the CNTs were uniform. From the SEM photograph, it can be seen that a tapered structure was formed at the CNT ends on the substrate side. Also, from the SEM photograph, it can be seen that a repeatedly uneven surface, a crimped shape, and an entangled structure were formed at the CNT ends on the substrate side in the length direction of the CNTs.

[0095] [Comparative Production Example 1 of CNT Array] The CNTs grown from the substrate after synthesis in Comparative CNT Synthesis Example 1 were peeled off in the same manner as in Production Example 1 of CNT Array to obtain a CNT array. An SEM photograph of the CNT ends on the substrate side of the obtained comparative CNT array is shown in Fig. 3B. Also, an SEM photograph of the substrate after CNT peeling is shown in Fig. 4B. Relatively long CNTs remained on the substrate after peeling, and they were non-uniform. It can be seen from the SEM photograph that the CNT ends on the substrate side are linear and do not have a specific structure.

[0096] [Production Examples 1 to 3 of CNT Sheet] By pinching and pulling out the ends of the CNTs grown from the substrate after synthesis and winding them using a winding roll, CNT sheets with lamination numbers of 10, 40, and 80 were obtained, respectively.

[0097] [Production Examples 1 to 4 of CNT-Resin Composite] After impregnating the CNT arrays and CNT sheets obtained in the above CNT array production example 1 and CNT sheet production examples 1 to 3 with an epoxy resin (EP-4100 manufactured by ADEKA), they were heat-cured to obtain CNT resin composite production examples 1 to 4. The results of measuring each physical property of the obtained CNT resin composites are shown in FIG. 5. The measurement of each physical property was performed under the following apparatus and conditions. The thermal diffusivity can be obtained from the thermal conductivity and specific heat. Thermal conductivity measurement: Thermo Wave Analyzer TA manufactured by BETTER (periodic heating radiation thermometry, at room temperature) Specific heat measurement: DSC7020 manufactured by Hitachi High-Tech (thermal flow rate indicating scanning calorimetry, at room temperature)

[0098] As described above, although the embodiments have been described, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims.

Industrial Applicability

[0099] The method for manufacturing a CNT product in the present disclosure can be used for manufacturing various articles containing CNTs (for example, heat dissipation materials).

Claims

1. A growth step of supplying a source gas to a reaction chamber containing a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; An exhaust step of exhausting the source gas to reduce the source gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the source gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, comprising a CNT synthesis process using a chemical vapor deposition method, the method comprising: using a halide of a transition metal element as a reaction catalyst; At least one second gas selected from the group consisting of a hydrocarbon having an oxygen atom, hydrogen, and carbon monoxide may be supplied simultaneously with the supply of the source gas. When the second gas is supplied, in the growth step, the second gas pressure ratio (second gas pressure / source gas pressure) with respect to the source gas pressure is 100% or less. A method for manufacturing a CNT product.

2. The method for manufacturing a CNT product according to claim 1, wherein the growth temperature is maintained in the holding step.

3. The method for manufacturing a CNT product according to claim 1 or 2, wherein the reaction catalyst is selected from the group consisting of iron fluoride, cobalt fluoride, nickel fluoride, iron chloride, cobalt chloride, nickel chloride, iron bromide, cobalt bromide, nickel bromide, iron iodide, cobalt iodide, and nickel iodide.

4. The method for manufacturing a CNT product according to any one of claims 1 to 3, wherein the second gas is supplied simultaneously with the supply of the source gas.

5. The method for manufacturing a CNT product according to any one of claims 1 to 4, wherein in the growth step, the growth temperature is 500 °C or higher and the source gas pressure is 1 Torr or higher.

6. The method for manufacturing a CNT product according to any one of claims 1 to 5, wherein the reduced pressure is 30% or more and 80% or less of the growth pressure.

7. The method for manufacturing a CNT product according to any one of claims 1 to 6, further comprising a temperature reduction step of reducing the reaction chamber atmosphere temperature after the holding step.

8. A growth step of supplying a source gas to a reaction chamber containing a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; An exhaust step of exhausting the source gas to reduce the source gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the source gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, comprising a CNT synthesis process using a chemical vapor deposition method, the method comprising: After the holding step, a second discharging step of discharging the raw material gas to make the raw material gas pressure 0.1 Torr or less is included. At the same time as the supply of the raw material gas, at least one second gas selected from the group consisting of hydrocarbons having oxygen atoms, hydrogen, and carbon monoxide may be supplied. When the second gas is supplied, in the growth step, the second gas pressure ratio (second gas pressure / raw material gas pressure) with respect to the raw material gas pressure is 100% or less. A method for manufacturing a CNT product.

9. After the holding step, a temperature-lowering step of lowering the reaction chamber atmosphere temperature is included. The second discharging step is performed simultaneously with the temperature-lowering step. The method for manufacturing a CNT product according to claim 8.

10. A growth step of supplying a raw material gas to a reaction chamber including a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; A discharging step of discharging the raw material gas to reduce the raw material gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the raw material gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, including a CNT synthesis process using a chemical vapor deposition method, including: A CNT array manufacturing process including a peeling step of peeling the CNTs grown on the substrate from the substrate; At the same time as the supply of the raw material gas, at least one second gas selected from the group consisting of hydrocarbons having oxygen atoms, hydrogen, and carbon monoxide may be supplied. When the second gas is supplied, in the growth step, the second gas pressure ratio (second gas pressure / raw material gas pressure) with respect to the raw material gas pressure is 100% or less. A method for manufacturing a CNT product.

11. A growth step of supplying a raw material gas to a reaction chamber including a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; A discharging step of discharging the raw material gas to reduce the raw material gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the raw material gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, including a CNT synthesis process using a chemical vapor deposition method, including: A CNT fiber product manufacturing process including a pulling-out step of pulling out the CNTs grown on the substrate as a CNT web from the substrate; At the same time as supplying the raw material gas, at least one second gas selected from the group consisting of hydrocarbons having oxygen atoms, hydrogen, and carbon monoxide may be supplied. When the second gas is supplied, in the growth step, the second gas pressure ratio (second gas pressure / raw material gas pressure) with respect to the raw material gas pressure is 100% or less. A method for manufacturing a CNT product.

12. A growth step of supplying a raw material gas to a reaction chamber including a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; An exhaust step of exhausting the raw material gas and reducing the raw material gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the raw material gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, including a CNT synthesis process using a chemical vapor deposition method, comprising: Growing CNTs on both sides of the substrate; At the same time as supplying the raw material gas, at least one second gas selected from the group consisting of hydrocarbons having oxygen atoms, hydrogen, and carbon monoxide may be supplied. When the second gas is supplied, in the growth step, the second gas pressure ratio (second gas pressure / raw material gas pressure) with respect to the raw material gas pressure is 100% or less. A method for manufacturing a CNT product.

13. A growth step of supplying a raw material gas to a reaction chamber including a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; An exhaust step of exhausting the raw material gas and reducing the raw material gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the raw material gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, including a CNT synthesis process using a chemical vapor deposition method, comprising: Using a substrate polished on both sides as the substrate; At the same time as supplying the raw material gas, at least one second gas selected from the group consisting of hydrocarbons having oxygen atoms, hydrogen, and carbon monoxide may be supplied. When the second gas is supplied, in the growth step, the second gas pressure ratio (second gas pressure / raw material gas pressure) with respect to the raw material gas pressure is 100% or less. A method for manufacturing a CNT product.

14. A growth step of supplying a raw material gas to a reaction chamber including a substrate and growing CNTs on the substrate under a growth temperature and a growth pressure; An exhaust step of exhausting the raw material gas and reducing the raw material gas pressure to a reduced pressure that is 5% or more and 95% or less of the growth pressure; A holding step of holding the raw material gas pressure within the range of the reduced pressure for a predetermined time; A method for manufacturing a CNT product, including a CNT synthesis process using a chemical vapor deposition method, comprising: The reaction chamber includes a plurality of the substrates, and the distance between the plurality of substrates is minimized within a range where the CNTs grown from each substrate do not contact each other. At the same time as the supply of the source gas, at least one second gas selected from the group consisting of hydrocarbons having oxygen atoms, hydrogen, and carbon monoxide may be supplied. When the second gas is supplied, in the growth step, the second gas pressure ratio (second gas pressure / source gas pressure) with respect to the source gas pressure is 100% or less. A method for manufacturing a CNT product.

15. The CNT product is an aggregate of CNTs, and among the CNTs, the ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point to the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less, forming a tapered structure. The method for manufacturing a CNT product according to any one of claims 1 to 14.

16. The CNT product is a CNT array which is an oriented aggregate of CNTs. On one surface, among the CNTs, the ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point to the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less, forming a tapered structure. The method for manufacturing a CNT product according to claim 15.

17. The CNT product is a CNT fiber product containing CNTs as fibers, and among the CNTs, a plurality of CNT ends The ratio (D1 / D2) of the average diameter D1 at 10 nm to 100 nm from each end point to the average diameter D2 at 1000 nm to 2000 nm from each end point is 0.75 or less, forming a tapered structure. The method for manufacturing a CNT product according to claim 15 or 16.

18. The CNT product is a CNT web, a CNT yarn, a CNT sheet, a CNT sheet, a CNT woven or knitted fabric, or a CNT non-woven fabric. The method for manufacturing a CNT product according to claim 17.

19. Among the CNTs, a plurality of CNT ends form a repeatedly uneven surface in the length direction of the CNTs. The method for manufacturing a CNT product according to any one of claims 15 to 18.

20. The plurality of CNT ends have a curled shape. The method for manufacturing a CNT product according to any one of claims 15 to 19.

21. The manufacturing method of a CNT product according to any one of claims 15 to 20, wherein the plurality of CNT ends form an entangled structure together with adjacent CNT ends.

22. A method for manufacturing a CNT resin composite, comprising a step of impregnating the CNT product obtained by the method for manufacturing a CNT product according to any one of claims 15 to 21 with a resin.

23. Use of the CNT product obtained by the method for manufacturing a CNT product according to any one of claims 15 to 21 or the CNT resin composite obtained by the method for manufacturing a CNT resin composite according to claim 22 as an article.

24. The use according to claim 23, wherein the article is selected from the group consisting of a heat dissipation material, a heater, and an electromagnetic wave absorption sheet.

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