WO2020031883A1 - Boron nitride nanotube material, boron nitride nanotube composite material, and method for producing boron nitride nanotube material - Google Patents

Boron nitride nanotube material, boron nitride nanotube composite material, and method for producing boron nitride nanotube material Download PDF

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WO2020031883A1
WO2020031883A1 PCT/JP2019/030442 JP2019030442W WO2020031883A1 WO 2020031883 A1 WO2020031883 A1 WO 2020031883A1 JP 2019030442 W JP2019030442 W JP 2019030442W WO 2020031883 A1 WO2020031883 A1 WO 2020031883A1
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boron nitride
fullerene
particles
bnnt
boron
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PCT/JP2019/030442
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French (fr)
Japanese (ja)
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岡井　誠
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日立金属株式会社
テクナ・プラズマ・システムズ・インコーポレーテッド
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Priority to JP2020535726A priority Critical patent/JP7284758B2/en
Publication of WO2020031883A1 publication Critical patent/WO2020031883A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/38—Boron-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C08K7/02—Fibres or whiskers
    • C08K7/04—Fibres or whiskers inorganic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C08K7/22—Expanded, porous or hollow particles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/02—Compositions of unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
    • C08L101/04—Compositions of unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing halogen atoms
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments

Definitions

  • the present invention relates to a boron nitride nanotube material, a boron nitride nanotube composite material, and a method for producing a boron nitride nanotube material.
  • boron nitride nanotubes have attracted attention as microfibrous substances.
  • a boron nitride nanotube (hereinafter, also referred to as “BNNT”) is a nanotube (NT) in which a sheet formed by alternately bonding nitrogen (N) atoms and boron (B) atoms forms a tubular body.
  • BNNT is said to have the same mechanical properties as carbon nanotubes (hereinafter referred to as “CNTs”), which are cylindrical bodies of sheets to which carbon (C) atoms are bonded.
  • CNTs carbon nanotubes
  • BNNT which is a ceramic material, has a feature that it has high thermal conductivity as well as high thermal stability.
  • BNNT has a larger band gap than CNT and is an electrically insulating material.
  • BNNT is more easily modified than CNT and has lower reactivity between BNNT and aluminum (Al), so that BNNT can be incorporated into an aluminum base material to form a metal matrix composite (MMC).
  • MMC metal matrix composite
  • Patent Document 1 As conventional techniques relating to BNNT, there are, for example, the following Patent Document 1 and Non-Patent Document 1.
  • ICP Inductively-coupled @ plasma
  • microfibrous substances such as CNT and BNNT are bundled and bundled by van der Waals' attractive force.
  • the van der Waals attractive force is a relatively weak attractive force.
  • the contact area is large, and the fine fibrous materials are attracted and come into contact with each other due to the form, so that a thick bundle is used. (Bundle shape).
  • the nanotubes are not bundled but rather spatially. It is necessary to be separated and uniformly dispersed.
  • Patent Document 1 and Non-Patent Document 1 do not discuss suppression of this bundling at all.
  • Non-Patent Document 2 describes a technique for suppressing the bundling by adding an aromatic dispersant to BNNT.
  • the dispersant may be adsorbed on the BNNT surface and contaminants such as carbon may be mixed into the BNNT material.
  • centrifugation for a long time or the like can be considered in addition to using a dispersant as in Non-Patent Document 2, but the process cost is increased. Therefore, it is important to prevent BNNTs from being bundled in the manufacturing process of the BNNT as early as possible.
  • an object of the present invention is to provide a BNNT material in which BNNTs are dispersed to minimize bundling, a method of manufacturing the BNNT material, and a BNNT composite material using the BNNT material.
  • One embodiment of the present invention for achieving the above object includes boron nitride nanotubes and boron nitride fullerene hollow particles, wherein the boron nitride fullerene hollow particles are dispersed between the boron nitride nanotubes. Boron nitride nanotube material.
  • another aspect of the present invention includes a base material, boron nitride nanotubes, and boron nitride fullerene hollow particles, wherein the boron nitride nanotubes and the boron nitride fullerene hollow particles are dispersed in the base material.
  • This is a boron nitride nanotube composite material.
  • another aspect of the present invention includes (a) a boron nitride nanotube, and boron nitride fullerene particles having boron nitride fullerene formed on the surface of boron particles, wherein the boron nitride fullerene particles are located between the boron nitride nanotubes.
  • BNNT material in which BNNTs are dispersed and bundling is minimized, a BNNT material manufacturing method, and a BNNT composite material using the BNNT material.
  • 7 is a graph showing a result of height distribution measurement by AFM of Comparative Example 1.
  • 7 is a graph showing a result of height distribution measurement by AFM of Comparative Example 2.
  • Scanning electron micrograph of an aluminum composite material produced using the BNNT material of the present invention Scanning electron micrograph of a cleaved surface of a resin composite material produced using the BNNT material of the present invention It is a schematic diagram which shows an example of an ICP apparatus.
  • FIG. 1 is a flow chart showing one example of the BNNT material of the present invention and a method for producing the same.
  • the method for producing a BNNT material of the present invention includes a BNNT growth step (S1) for growing BNNT by an ICP apparatus, an oxidation heat treatment step (S2), and an oxide removal step (S3).
  • FIG. 1 also shows a schematic diagram of a product in each step.
  • the BNNT material of the present invention and the process of its manufacturing method will be described with reference to the drawings.
  • FIG. 13 is a schematic diagram illustrating an example of an ICP device.
  • the ICP apparatus 20 includes a plasma torch 21 for generating plasma, a reaction vessel 22 for reacting the BNNT raw material with the plasma, a cyclone 23 for recovering the BNNT material, And a filter 24 for collecting raw materials and the like.
  • the inside of the reaction vessel 22 of the ICP apparatus 20 is purged with a plasma gas.
  • plasma is generated in the reaction vessel 22 by the plasma torch 21.
  • the plasma gas is not particularly limited, but is preferably argon (Ar), helium (He), hydrogen (H 2 ), nitrogen (N 2 ), or a mixed gas thereof.
  • h-BN powder can be supplied to the plasma torch by, for example, controlling the supply amount by a feeder (not shown in FIG. 1) and using a carrier gas (Ar or the like).
  • the average particle size of the h-BN powder is preferably 1 to 20 ⁇ m (1 ⁇ m or more and 20 ⁇ m or less).
  • BNNT growth step (S1) fibrous BNNT1 and boron particles 2 are formed from the above-described chemical reaction between the h-BN powder and nitrogen gas. Then, as shown in the enlarged view, the boron particles 2 become a product in which boron nitride fullerene 3 is generated on the surface, that is, boron nitride fullerene particles (hereinafter, also referred to as BN fullerene particles) 4.
  • Boron nitride fullerene refers to a material having a graphene structure in which B atoms and N atoms are alternately bonded, and having a structure closed spherically or oblong.
  • the single BN fullerene particles 4 are dispersed and mixed between the BNNTs 1 (distributedly exist). Thereby, bundling of BNNT can be suppressed, and BNNT1 is easily dispersed. That is, the BNNT material is present in what is called a bundle of several to several tens of BNNTs in a bundle, and the bundle is generally intricately intertwined with other bundles. However, the BN fullerene particles 4 adhere to the surface of the BNNT 1 by the van der Waals attractive force, so that the BN fullerene particles 4 are appropriately interposed between the BNNTs 1 in the bundle.
  • the BN fullerene particles 4 prevent physical steric hindrance and prevent BNNTs from being bundled, so that BNNTs can be easily dispersed and BNNTs can be less bundled.
  • the bundling can be suppressed in the manufacturing process at the early stage of the synthesis of the BNNT material, and as a result, the BNNT material with the bundling suppressed to a minimum can be obtained.
  • a product having a growth body in which BNNT grows and extends from the surface of the BN fullerene 3 with the BN fullerene particle 4 as a nucleus (hereinafter, referred to as a “BN fullerene particle with growth body 4b”) is formed.
  • the BN fullerene particles 4 may be referred to as BN fullerene particles 4a having no growth body (hereinafter, may be simply referred to as “BN fullerene particles” or “single BN fullerene particles” when particularly distinguished.).
  • BN fullerene particle 4b with a growth body is referred to as BN fullerene particles 4a having no growth body.
  • the BN fullerene particles 4b with the growth body may be dispersed and mixed (present separately) between the BNNTs 1 together with the single BN fullerene particles 4a. Since the BN fullerene particles 4a with the growth body are also interposed between the BN fullerene particles 4a and the single BN fullerene particles 4a between the BNNTs 1 in the bundle, the BN fullerene particles 4b serve as a physical steric hindrance, so that the BNNTs are easily dispersed and the BNNTs are bundled. Can be reduced.
  • BN fullerene particles 4a and the BN fullerene particles with growth bodies 4b are generated, BNNT is grown from only some BN fullerene particles, and other BN fullerene particles are not grown. It is also possible to form a mixture of a large number of BN fullerene particles 4a and a small number of BN fullerene particles with growth 4b, and disperse and mix them between the BNNTs 1.
  • the power (plasma power) applied to the plasma torch is adjusted. That is, the plasma power is adjusted so that the region where the temperature of the plasma is higher than 2700 ° C. (corresponding to the melting point of boron nitride) is made as long as possible.
  • the degree of dispersion of the BN fullerene hollow particles to be described later largely depends on the degree of dispersion of the BN fullerene particles at this stage. Therefore, at this stage, it is important to uniformly disperse the BN fullerene particles between the BNNTs.
  • the BNNT growth step for example, a condition in which the entire gas flow becomes laminar without being turbulent is selected, and the BN fullerene particles are formed to have a uniform size to some extent and a certain amount or more. It is desirable.
  • FIG. 2 is a low magnification transmission electron microscope (TEM) photograph of the product obtained by the BNNT growth step. As shown in FIG. 2, it has BNNT101 and BN fullerene particles 102. Although not shown in FIG. 2 because of low magnification, the BN fullerene particles 102 include a single BN fullerene particle and a BN fullerene particle with a growth body. In the BNNT 101, a product 101a that looks thin and a product 101b that looks thick are mixed, but the product 101b that looks thick is a BNNT bundled by van der Waals attraction (for example, see FIG. 7 described later).
  • TEM transmission electron microscope
  • the BNNT material of the present invention suppresses bundling due to the presence of BN fullerene particles, as described above.
  • the average particle diameter of the BN fullerene particles 102 was 5 nm to 100 nm.
  • the average particle size of the BN fullerene particles 4 is preferably in the range of 5 nm to 100 nm, more preferably in the range of 5 nm to 30 nm.
  • the average particle size of the BN fullerene particles can be controlled by ICP growth conditions (flow rate of raw material gas and supply speed of raw material).
  • the average particle size of the BN fullerene hollow particles is preferably in the range of 5 nm to 100 nm. The range is more preferably from 5 nm to 30 nm.
  • FIG. 3 is a high magnification transmission electron micrograph of BNNT contained in the product obtained by the BNNT growth step.
  • the BNNT includes two layers of BNNT201 and three layers of BNNT202.
  • BNNT material manufactured according to the present invention about 2% to 4 layers of BNNT accounted for about 60% of the whole, and in addition, a single layer and 5 layers or more of BNNT were included.
  • the number of BNNT layers is preferably 2 or more and 5 or less. As the number of BNNT layers is reduced, the mechanical strength such as tensile strength and Young's modulus of the composite material is improved by adding a small amount. Can be done.
  • the BN fullerene particles and the BN fullerene hollow particles described below also have a multilayer structure, and it is preferable that the number of these layers is two or more and five or less as in the case of BNNT.
  • the number of layers can be increased or decreased by changing the growth conditions of the ICP (eg, the length of the plasma region).
  • the average diameter of BNNT was in the range of 4 nm to 6 nm.
  • the average diameter of BNNT is larger than 50 nm, the BNNT becomes too large with respect to the BN fullerene particles to increase rigidity and reduce the dispersion effect.
  • BNNT is preferably grown to an average diameter of 1 nm or more and 50 nm or less.
  • the thickness is more preferably 1 nm or more and 25 nm or less, and further preferably 1 nm or more and 10 nm or less.
  • the average diameter of BNNT can be controlled by ICP growth conditions (flow rate of plasma gas and supply rate of raw material).
  • the average particle diameter of the BN fullerene particles and the average diameter of the BNNT can be determined by directly measuring the particle diameters of a large number of BN fullerene particles and the diameter of the BNNT on a scanning electron microscope (Scanning Electron Microscope: SEM) or an TEM observation photograph ( (For example, 30), and can be obtained by arithmetic mean of these measured values.
  • FIG. 4 is a high magnification transmission electron micrograph of BN fullerene particles contained in the product obtained by the BNNT growth step.
  • the surface of the boron particles 301 is covered with a BN fullerene 302 having a multilayer structure, and an amorphous component 303 containing N, B and H (hydrogen) adheres to the surface of the BN fullerene 302. are doing.
  • BN fullerene can be identified by electron diffraction.
  • the amorphous component can be identified by energy dispersive X-ray analysis (Energy @ Dispersive @ X-ray @ spectrometry: EDX).
  • the ratio of the specific surface area of the BN fullerene particles to the BNNT is approximately the same within a range of 1:10 to 10: 1.
  • the specific surface area of BNNT is more than 10 times the specific surface area of the BN fullerene particles, the BNNT becomes difficult to disperse.
  • the specific surface area of BNNT be 0.1 to 10 times the specific surface area of the BN fullerene particles.
  • the specific surface area of BNNT is preferably in the range of about 200 to 400 m 2 / g. However, when it is difficult to control the specific surface area, the amount of BN fullerene particles with respect to BNNT can be controlled and replaced.
  • the above preferred range can be applied by replacing the specific surface area of the BN fullerene particles with the specific surface area of the BN fullerene hollow particles in the BNNT material. That is, the measurement is performed using BN fullerene hollow particles from which the boron component has been removed after the oxidation heat treatment step described below.
  • the specific surface area of BNNT and BN fullerene hollow particles can be measured by a gas adsorption method such as a BET (Brunauer-Emmett-Teller) method (for example, BELSORP-maxII manufactured by Microtrac BEL).
  • the oxidation heat treatment step (S2) the boron particles 2 of the BN fullerene particles 4 contained in the first product (hereinafter, referred to as “first product”) obtained in the BNNT growth step (S1) are oxidized.
  • first product the first product obtained in the BNNT growth step (S1)
  • second product boron oxide
  • the oxidation treatment is preferably performed in air at a temperature of 450 ° C. or more and 1000 ° C. or less for 3 hours or more. The higher the heating temperature, the shorter the heat treatment time. If the heating temperature is lower than 450 ° C., the boron particles are not easily oxidized, and the processing time is undesirably long.
  • the temperature exceeds 1000 ° C.
  • BNNT is burned and the yield is undesirably reduced.
  • the temperature is more preferably from 500 ° C to 900 ° C, further preferably from 600 ° C to 900 ° C, and most preferably from 700 ° C to 900 ° C.
  • a treatment time of 3 hours is sufficient to oxidize the boron particles to boron oxide (B 2 O 3 ).
  • the boron particles 2 can be converted into the boron oxide particles 6, and the amorphous components (N, H) attached to the surfaces of the BN fullerene particles 4 can be oxidized and eliminated.
  • the purity of the BNNT material can be increased.
  • the boron particles can be similarly changed to boron oxide particles for the BN fullerene particles 4b with the grown body.
  • the oxide removing step (S3) will be described.
  • the boron oxide (B 2 O 3 ) generated in the oxidation treatment step (S2) is removed by, for example, dissolving with a cleaning solution, and the BN fullerene 3 is used as an outer layer, and the BNNT growth is present.
  • BN fullerene hollow particles 7 (hereinafter referred to as “BN fullerene hollow particles”) are formed. Thereby, a second product in which at least the BN fullerene hollow particles 7 are dispersed between the BNNTs 1 is obtained.
  • the second product is further purified, and by appropriately interposing the BN fullerene hollow particles 7 between the BNNTs 1 in the bundle, the BNNTs 1 are easily dispersed and the bundling is minimized.
  • High purity BNNT material The mechanism and effect of reducing the bundling by the BN fullerene particles 7 are the same as those of the BN fullerene particles 4 described above, and thus the description is omitted.
  • the product formed in the BNNT growth step is a mixture of the BN fullerene particles 4a and the BN fullerene particles 4b with the growing body
  • the boron oxide (B 2 O 3 ) contained in the BN fullerene particles with the growing body 4b is included.
  • the BN fullerene hollow particles 7b (hereinafter, referred to as “growth-bearing BN fullerene hollow particles”) having growth bodies, in which BNNTs have grown and extended from the surfaces of the hollow particles, are dispersed in the same manner. It can also be included.
  • a high-purity BNNT material 10 in which a single BN fullerene hollow particle 7a and a grown BN fullerene hollow particle 7b are mixed can be obtained.
  • the washing liquid is not particularly limited as long as it can dissolve B 2 O 3 , but ethanol, methanol or water is preferable. Further, by using the ultrasonic cleaning treatment here, the degree of dispersion of the BN fullerene hollow particles can be improved to some extent together with the cleaning and removal.
  • the oxidation heat treatment step (S2) and the oxide removal step (S3) are also collectively referred to as a “purification step”.
  • FIG. 5A is a low magnification transmission electron micrograph of the first product before the purification step (after the BNNT growth step), and FIG. 5B is a low-resolution transmission electron micrograph of the second product after the purification step. It is a transmission electron micrograph of magnification.
  • the BN fullerene particles of the first product and the BN fullerene hollow particles of the second product are both dispersed between BNNTs.
  • the boron component is removed from the BN fullerene particles 4, and the BN fullerene covering the surface of the boron particles is removed. Only the remaining BN fullerene hollow particles 401 are formed. Since it is difficult to completely remove the boron component, if a hollow portion can be confirmed as shown in FIG. 5B, it is regarded as BN fullerene hollow particles.
  • the amorphous components containing N and H are also burned off, and finally, as described above, the BNNT material in which the BNNT and the BN fullerene hollow particles are mixed, or the BNNT material and the BN fullerene hollow A BNNT material in which the particles and the BN fullerene hollow particles with the growing body are mixed can be obtained.
  • FIG. 6 is a high magnification transmission electron micrograph showing the highly dispersed BNNT material of the present invention.
  • the highly dispersed BNNT material it can be seen that the BN fullerene hollow particles 502 formed from the BN fullerene particles are in contact with the BNNT 501 and are interposed therebetween, whereby bundling is suppressed.
  • FIG. 7 is a high magnification transmission electron micrograph of a conventional BNNT material using only BNNT. It can be seen that a plurality of BNNTs overlap and the bundles are entangled.
  • the BNNT material shown in FIG. 7 is manufactured by removing BN fullerene hollow particles from the BNNT material.
  • a separation technique such as a centrifugal separation method can be used.
  • the BN fullerene particles are formed in the BNNT growth step, and BN fullerene hollow particles are formed from the BN fullerene particles in the high-purification step. Then, at least the BN fullerene hollow particles are left in the BNNT material.
  • the BN fullerene hollow particles are dispersed between a large number of BNNTs, and the BNNTs are easily dispersed, and bundling is suppressed, that is, a highly dispersed BNNT material can be obtained.
  • BN fullerene particles with growth bodies are also formed, and BN fullerene particles with growth bodies are formed from the BN fullerene particles with growth bodies, and the BN fullerene particles with growth bodies are dispersed and mixed together with the BN fullerene hollow particles in BNNT. To obtain a BNNT material.
  • the specific surface area of BNNT should be 0.1 to 10 times the specific surface area of the BN fullerene particles, and the average particle diameter of the BN fullerene particles and the BN fullerene particles with growth bodies is 5 nm. It has been described that the thickness is preferably 100 nm or less, that the BNNT and BN fullerene particles have a multilayer structure of 2 to 5 layers, and that the average diameter of the BNNT is preferably 1 nm to 50 nm. Since these forms are basically maintained in the BNNT growth step to the high-purification step, these requirements are also provided in the final BNNT material obtained after the high-purification step.
  • the above-described BN fullerene particles can be replaced with hollow BN fullerene particles, and the BN fullerene particles with growth bodies can be replaced with hollow BN fullerene particles with growth bodies, and the description thereof is omitted.
  • ICP is used in the BNNT growth step
  • laser vaporization, thermal decomposition, and DC plasma can be used instead of ICP.
  • BNNT material of the present invention (sample of Example 1) and, as a comparison, a BNNT material (sample of Comparative Example 1) prepared by removing BN fullerene hollow particles from the BNNT material of the present invention.
  • a BNNT material prepared by separately preparing and mixing BNNT and BN fullerene hollow particles (Comparative Example) 2 samples). The degree of bundling of the above Example 1, Comparative Example 1 and Comparative Example 2 was evaluated.
  • Example 2 The BNNT material of Example 1 was produced in the following manner.
  • a small-sized plasma device manufactured by TEKNA Plasma Systems Inc., model: TekNano-15
  • argon gas flow rate: 10 L / min
  • a mixed gas of argon (30 L / min) and hydrogen 2.5 L / min
  • Nitrogen gas flows through both the torch nozzle (10 L / min) and the porous wall (47 L / min) surrounding the reaction vessel.
  • the apparatus was disassembled and the products adhered to the plasma torch, the reactor, the cyclone, and the filter were recovered.
  • the collected product is oxidized in air at 800 ° C. for 3 hours (oxidation heat treatment step (S2)), and then washed with ethanol to remove boron components such as boron oxide (oxide removal step). (S3)) to obtain a sample of Example 1.
  • Most of the obtained BN fullerene hollow particles were in the particle size range of 5 to 50 nm, and had an average particle size of 30 nm.
  • BNNTs having 2 to 4 layers accounted for about 60% of the total, and their diameters were in the range of 4 to 6 nm.
  • Example 1 The sample of Example 1 was subjected to a centrifugal separation treatment for one hour, and the product obtained by removing the BN fullerene hollow particles was used as a sample of Comparative Example 1. In this sample, as shown in FIG. 7, it was confirmed that the plurality of BNNTs overlapped and the entanglement between the bundles increased.
  • BNNTs have already formed a certain amount of bundles due to van der Waals attractive force. Therefore, even if BN fullerene hollow particles are mixed with the BNNTs, the bundles cannot be loosened and the effect of dispersing them is not obtained. Not confirmed.
  • Example 1 and Comparative Example 1 the degree of bundling of Example 1 and Comparative Example 1 was evaluated. Specifically, an ethanol solution containing 0.1% by mass of the samples of Example 1 and Comparative Example 1 was prepared, and the solution was dropped on a silicon wafer, and after the ethanol was completely evaporated, the sample was removed. analyzed. The height distribution of this sample was measured using an atomic force microscope (Atomic Force Microscope; AFM). When the BNNTs are dispersed without being bundled, the height distribution becomes a distribution having a peak centered around the diameter of the BNNT. On the other hand, when bundled, the height distribution indicates a height corresponding to a plurality of BNNTs, so that the height distribution is a value larger than the diameter.
  • AFM atomic force microscope
  • FIG. 8 is a graph showing the results of height distribution measurement by the AFM of Example 1.
  • the AFM measurement was performed in the contact mode.
  • BNNTs are distributed around a mean diameter of about 6 nm of the BNNTs measured by a transmission electron microscope, so that the BN fullerene hollow particles are dispersed between the BNNTs, so that the BNNTs are isolated. It can be seen that they are dispersed.
  • FIG. 8 does not show the measurement results of the BN fullerene hollow particles contained in the BNNT material. This is because BNNT is firmly fixed by van der Waals force during AFM measurement, but can be measured, but BN fullerene hollow particles move due to the contact of the AFM probe, resulting in noise that cannot be measured. .
  • FIG. 9 is a graph showing the results of height distribution measurement by AFM of Comparative Example 1. As shown in FIG. 9, the sample of Comparative Example 1 is distributed around 17 nm, which is considerably larger than the average diameter of BNNT measured by a transmission electron microscope, which is 6 nm. Understand.
  • FIG. 10 is a graph showing the result of height distribution measurement by AFM of Comparative Example 2. As shown in FIG. 10, similarly to the sample of Comparative Example 1, the sample of Comparative Example 2 is distributed around 17 nm, which is considerably larger than the average diameter of BNNT measured by a transmission electron microscope, which is 6 nm. It can be seen that BNNT is bundled.
  • Example 1 and Comparative Example 2 From the results of Example 1 and Comparative Example 1, it was found that BNNT bundling could not be suppressed in the state where BN fullerene hollow particles were not included. Further, from the results of Example 1 and Comparative Example 2, it was found that even if BN fullerene hollow particles were mixed after the synthesis of BNNT, BNNT bundling could not be suppressed. That is, it was found that by simultaneously generating and dispersing BN fullerene in the early stage of the synthesis of BNNT, a highly dispersed BNNT material in which BNNT was dispersed and bundle formation was suppressed was obtained.
  • BNNT composite material of Example 2 [Production and evaluation of BNNT composite material of Example 2] Using the sample of Example 1, a BNNT composite material using aluminum as a base material was produced. Various BNNT composite materials such as a metal composite material and a resin composite material can be manufactured using the highly dispersed BNNT material in which bundling of the present invention is suppressed.
  • a BNNT composite material a composite material of BNNT and aluminum (BNNT / Al composite material) and a composite material of BNNT and fluororesin (BNNT / fluororesin composite material) were produced.
  • the BNNT / Al composite material was prepared by charging the BNNT material of Example 1 into a molten aluminum and solidifying the same.
  • the content of the BNNT material is 5% by mass.
  • FIG. 11 is a scanning electron micrograph of the surface of a BNNT / Al composite material produced using the BNNT material of the present invention. As shown in FIG. 11, BNNT901 sneaks into the aluminum base material, and the surface is covered with alumina, so that it looks thick.
  • BNNT composite material of Example 3 a composite material of BNNT and a fluororesin having a base material as a fluorine-containing resin was produced.
  • the BNNT / fluororesin composite material was prepared by mixing an organic solution of the fluorine-containing resin and the organic solution of the BNNT material of Example 1 described above, and then drying and removing the organic solvent.
  • the content of the BNNT material is 5% by mass.
  • FIG. 12 is a scanning electron micrograph of the surface of a BNNT / fluororesin composite material produced using the BNNT material of the present invention.
  • FIG. 12 shows the BNNT / fluororesin composite material produced by freezing it in liquid nitrogen and observing the cleaved surface with a scanning electron microscope. As shown in FIG. 12, BNNT1001 in the BNNT / fluororesin composite material appears to jump out of the resin cleavage surface.
  • a sample in which the BNNT material was not mixed with the fluorine-containing resin and a sample of the BNNT / fluororesin composite material described above were prepared, and the coefficient of thermal expansion was measured using a thermal expansion measuring device (manufactured by NETZSCH, model: DIL402). .
  • the coefficient of thermal expansion of the sample of the BNNT / fluororesin composite material was 30% lower than that of the sample containing no BNNT material.
  • the resin composite material using the BNNT material of the present invention can sufficiently exhibit the characteristics of the BNNT material, such as a reduction in the coefficient of thermal expansion, by suppressing bundling.
  • a thermosetting resin, a thermoplastic resin, a chlorine, iodine or bromine-containing resin, or an arbitrary mixture thereof can be used in addition to the fluororesin.
  • the BN fullerene hollow particles are dispersed between the BNNTs, whereby the BNNT material is dispersed and the bundling is suppressed, and the method for producing the BNNT material, and It has been demonstrated that a high-strength composite material and a low-thermal-expansion composite material using a BNNT material can be provided.
  • the present invention is not limited to the above-described embodiments, but includes various modifications.
  • the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above.
  • a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment.
  • ICP device 21 ... plasma torch, 22 ... reaction vessel, 23 ... cyclone, 24 ... filter, 201 ... double-walled boron nitride nanotube, 202 ... 3-walled boron nitride nanotube, 303 ... amorphous component, 601 ... bundle of boron nitride nanotube , 9 1 ... BNNTs / aluminum composites of boron nitride nanotubes, 1001 ... BNNTs / fluororesin composite boron nitride nanotubes in the material.

Abstract

Provided are: a BNNT material in which BNNT is dispersed and bundling is minimized, and a BNNT composite material using the same; and a method for producing a BNNT material. This boron nitride nanotube material (10) is characterized by including boron nitride nanotubes (1), and boron nitride fullerene hollow particles (7), wherein the boron nitride fullerene hollow particles (7) are dispersed between the boron nitride nanotubes (1).

Description

窒化ホウ素ナノチューブ材料、窒化ホウ素ナノチューブ複合材料、及び窒化ホウ素ナノチューブ材料の製造方法Boron nitride nanotube material, boron nitride nanotube composite material, and method for producing boron nitride nanotube material
　本発明は、窒化ホウ素ナノチューブ材料、窒化ホウ素ナノチューブ複合材料、及び窒化ホウ素ナノチューブ材料の製造方法に関する。 The present invention relates to a boron nitride nanotube material, a boron nitride nanotube composite material, and a method for producing a boron nitride nanotube material.
　近年、微小繊維状物質として窒化ホウ素ナノチューブが注目されている。窒化ホウ素ナノチューブ（以下、「ＢＮＮＴ」とも称する。）とは、窒素（Ｎ）原子とホウ素（Ｂ）原子とが交互に結合したシートが筒状体を形成したナノチューブ（ＮＴ）である。ＢＮＮＴは、炭素（Ｃ）原子が結合したシートの筒状体であるカーボンナノチューブ（以下、「ＣＮＴ」と称する。）と同等の機械的特性を有するとされている。さらに、セラミック材料であるＢＮＮＴは、熱伝導率が高いだけでなく、熱安定性が高いと言う特長がある。ＢＮＮＴは、ＣＮＴよりもバンドギャップが大きく、電気絶縁材料である。また、ＢＮＮＴはＣＮＴよりも分子修飾しやすく、さらにＢＮＮＴとアルミニウム（Ａｌ）との反応性が低いため、金属マトリックス複合体（ＭＭＣ）を形成するためにアルミニウム母材に組み込むことができる。 ホ ウ 素 In recent years, boron nitride nanotubes have attracted attention as microfibrous substances. A boron nitride nanotube (hereinafter, also referred to as “BNNT”) is a nanotube (NT) in which a sheet formed by alternately bonding nitrogen (N) atoms and boron (B) atoms forms a tubular body. BNNT is said to have the same mechanical properties as carbon nanotubes (hereinafter referred to as “CNTs”), which are cylindrical bodies of sheets to which carbon (C) atoms are bonded. Furthermore, BNNT, which is a ceramic material, has a feature that it has high thermal conductivity as well as high thermal stability. BNNT has a larger band gap than CNT and is an electrically insulating material. In addition, BNNT is more easily modified than CNT and has lower reactivity between BNNT and aluminum (Al), so that BNNT can be incorporated into an aluminum base material to form a metal matrix composite (MMC).
　従来のＢＮＮＴに関する技術として、例えば以下の特許文献１及び非特許文献１がある。これらの文献では、ＢＮＮＴを高周波誘導プラズマ（Ｉｎｄｕｃｔｉｖｅｌｙ－ｃｏｕｐｌｅｄ　ｐｌａｓｍａ、以下「ＩＣＰ」と称する。）によって成長させることで、小径のＢＮＮＴを大量に製造することができるとされている。 技術 As conventional techniques relating to BNNT, there are, for example, the following Patent Document 1 and Non-Patent Document 1. In these documents, it is stated that by growing BNNT by high-frequency induction plasma (Inductively-coupled @ plasma, hereinafter referred to as "ICP"), a large amount of small-diameter BNNT can be produced.
　ところで、ＣＮＴやＢＮＮＴ等の微小繊維状物質は、ファンデルワールス引力により束ねられバンドル化することが良く知られている。ファンデルワールス引力は、比較的微弱な引力ではあるが、ＢＮＮＴのような微小繊維状物質の場合は、接触面積が大きく、その形態から微小繊維状物質同士が引き寄せられて接触するため、太い束状（バンドル状）になりやすい。しかしながら、例えばＭＭＣの中のＢＮＮＴを最大限に活用し、機械強度等の特性が複合材料の全体的な特性を最大限に引出すためには、それぞれのナノチューブを束状ではなく、むしろ空間的に分離され均一に分散された状態とすることが必要である。しかしながら、上記特許文献１や非特許文献１では、このバンドル化の抑制については何ら検討されていない。 By the way, it is well known that microfibrous substances such as CNT and BNNT are bundled and bundled by van der Waals' attractive force. The van der Waals attractive force is a relatively weak attractive force. However, in the case of a fine fibrous material such as BNNT, the contact area is large, and the fine fibrous materials are attracted and come into contact with each other due to the form, so that a thick bundle is used. (Bundle shape). However, in order to maximize the BNNTs in the MMC, for example, and to maximize the overall properties of the composite, such as mechanical strength, the nanotubes are not bundled but rather spatially. It is necessary to be separated and uniformly dispersed. However, Patent Document 1 and Non-Patent Document 1 do not discuss suppression of this bundling at all.
　非特許文献２には、ＢＮＮＴに、芳香族系分散材を加えてバンドル化を抑制する技術が記載されている。 Non-Patent Document 2 describes a technique for suppressing the bundling by adding an aromatic dispersant to BNNT.
特表２０１６－５２１２４０号公報JP-T-2016-521240
　上述した非特許文献２のように分散剤を使用する場合、分散剤がＢＮＮＴ表面に吸着してＢＮＮＴ材料にカーボン等のコンタミが混入する恐れがある。バンドル化したＢＮＮＴを分散させる手段として、非特許文献２のように分散剤を用いる他に、長時間の遠心分離等が考えられるが、プロセスコストがかさむ。したがって、ＢＮＮＴの合成段階の出来るだけ早い製造過程でＢＮＮＴのバンドル化を防ぐことが重要となる。 場合 When a dispersant is used as in Non-Patent Document 2 described above, the dispersant may be adsorbed on the BNNT surface and contaminants such as carbon may be mixed into the BNNT material. As means for dispersing the bundled BNNTs, centrifugation for a long time or the like can be considered in addition to using a dispersant as in Non-Patent Document 2, but the process cost is increased. Therefore, it is important to prevent BNNTs from being bundled in the manufacturing process of the BNNT as early as possible.
　本発明は、上記事情に鑑み、ＢＮＮＴを分散させてバンドル化を最小限に抑えたＢＮＮＴ材料と、ＢＮＮＴ材料の製造方法、及びＢＮＮＴ材料を用いたＢＮＮＴ複合材料を提供することを目的とする。 In view of the above circumstances, an object of the present invention is to provide a BNNT material in which BNNTs are dispersed to minimize bundling, a method of manufacturing the BNNT material, and a BNNT composite material using the BNNT material.
　上記目的を達成するための本発明の一態様は、窒化ホウ素ナノチューブと、窒化ホウ素フラーレン中空粒子とを含み、前記窒化ホウ素フラーレン中空粒子が前記窒化ホウ素ナノチューブの間に分散されていることを特徴とする窒化ホウ素ナノチューブ材料である。 One embodiment of the present invention for achieving the above object includes boron nitride nanotubes and boron nitride fullerene hollow particles, wherein the boron nitride fullerene hollow particles are dispersed between the boron nitride nanotubes. Boron nitride nanotube material.
　また、本発明の他の態様は、母材と、窒化ホウ素ナノチューブと、窒化ホウ素フラーレン中空粒子とを含み、前記窒化ホウ素ナノチューブと前記窒化ホウ素フラーレン中空粒子とが前記母材に分散されていることを特徴とする窒化ホウ素ナノチューブ複合材料である。 Further, another aspect of the present invention includes a base material, boron nitride nanotubes, and boron nitride fullerene hollow particles, wherein the boron nitride nanotubes and the boron nitride fullerene hollow particles are dispersed in the base material. This is a boron nitride nanotube composite material.
　また、本発明の他の態様は、（ａ）窒化ホウ素ナノチューブと、ホウ素粒子の表面に窒化ホウ素フラーレンが形成された窒化ホウ素フラーレン粒子とを含み、前記窒化ホウ素フラーレン粒子が前記窒化ホウ素ナノチューブの間に分散されている第１の生成物を得る工程と、（ｂ）前記（ａ）の工程で得られた前記第１の生成物に含まれる前記窒化ホウ素フラーレン粒子からホウ素成分を除去して窒化ホウ素フラーレン中空粒子を生成し、前記窒化ホウ素フラーレン中空粒子が窒化ホウ素ナノチューブの間に分散されている第２の生成物を得る工程と、を有することを特徴とする窒化ホウ素ナノチューブ材料の製造方法である。 Further, another aspect of the present invention includes (a) a boron nitride nanotube, and boron nitride fullerene particles having boron nitride fullerene formed on the surface of boron particles, wherein the boron nitride fullerene particles are located between the boron nitride nanotubes. (B) removing a boron component from the boron nitride fullerene particles contained in the first product obtained in the step (a) to obtain a first product dispersed in the first product; Producing boron fullerene hollow particles and obtaining a second product in which the boron nitride fullerene hollow particles are dispersed between boron nitride nanotubes. is there.
　本発明のより具体的な構成は、発明を実施するための形態に記載される。 よ り A more specific configuration of the present invention is described in the detailed description.
　本発明によれば、ＢＮＮＴが分散し、バンドル化が最小限に抑制されたＢＮＮＴ材料と、ＢＮＮＴ材料の製造方法、及びＢＮＮＴ材料を用いたＢＮＮＴ複合材料を提供することができる。 According to the present invention, it is possible to provide a BNNT material in which BNNTs are dispersed and bundling is minimized, a BNNT material manufacturing method, and a BNNT composite material using the BNNT material.
　上記した以外の課題、構成および効果は、以下の実施形態の説明により明らかにされる。 The problems, configurations, and effects other than those described above will be apparent from the following description of the embodiments.
本発明のＢＮＮＴ材料と、その製造方法の一例を示すフロー図Flow chart showing an example of the BNNT material of the present invention and a method for producing the same. ＢＮＮＴ成長工程によって得られた生成物の低倍率の透過型電子顕微鏡写真Low magnification transmission electron micrograph of the product obtained by the BNNT growth process ＢＮＮＴ成長工程によって得られた生成物に含まれるＢＮＮＴの高倍率の透過型電子顕微鏡写真High magnification transmission electron micrograph of BNNT contained in the product obtained by the BNNT growth process ＢＮＮＴ成長工程によって得られた生成物に含まれるホウ素粒子の高倍率の透過型電子顕微鏡写真High magnification transmission electron micrograph of boron particles contained in the product obtained by the BNNT growth process 高純度化工程前（ホウ素成分除去前）のＢＮＮＴ材料の低倍率の透過型電子顕微鏡写真Low magnification transmission electron micrograph of the BNNT material before the purification process (before removing the boron component) 高純度化工程後（ホウ素成分除去後）のＢＮＮＴ材料の低倍率の透過型電子顕微鏡写真Low magnification transmission electron micrograph of BNNT material after high purification process (after removal of boron component) 本発明のＢＮＮＴ材料の高倍率の透過型電子顕微鏡写真High magnification transmission electron micrograph of the BNNT material of the present invention ＢＮＮＴだけとしたＢＮＮＴ材料の高倍率の透過型電子顕微鏡写真High magnification transmission electron micrograph of BNNT material with only BNNT 実施例１のＡＦＭによる高さ分布測定結果を示すグラフ4 is a graph showing a result of height distribution measurement by the AFM of Example 1. 比較例１のＡＦＭによる高さ分布測定結果を示すグラフ7 is a graph showing a result of height distribution measurement by AFM of Comparative Example 1. 比較例２のＡＦＭによる高さ分布測定結果を示すグラフ7 is a graph showing a result of height distribution measurement by AFM of Comparative Example 2. 本発明のＢＮＮＴ材料を用いて作製したアルミ複合材料の走査型電子顕微鏡写真Scanning electron micrograph of an aluminum composite material produced using the BNNT material of the present invention 本発明のＢＮＮＴ材料を用いて作製した樹脂複合材料の劈開した表面の走査型電子顕微鏡写真Scanning electron micrograph of a cleaved surface of a resin composite material produced using the BNNT material of the present invention ＩＣＰ装置の一例を示す模式図である。It is a schematic diagram which shows an example of an ICP apparatus.
　以下、本発明の実施形態について図面を参照しながら説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　図１は本発明のＢＮＮＴ材料と、その製造方法の一例を示すフロー図である。図１に示すように、本発明のＢＮＮＴ材料の製造方法は、ＩＣＰ装置によりＢＮＮＴを成長させるＢＮＮＴ成長工程（Ｓ１）、酸化熱処理工程（Ｓ２）及び酸化物除去工程（Ｓ３）を有している。図１では、各工程における生成物の模式図も併記している。以下、本発明のＢＮＮＴ材料と、その製造方法の過程を図面と共に説明する。 FIG. 1 is a flow chart showing one example of the BNNT material of the present invention and a method for producing the same. As shown in FIG. 1, the method for producing a BNNT material of the present invention includes a BNNT growth step (S1) for growing BNNT by an ICP apparatus, an oxidation heat treatment step (S2), and an oxide removal step (S3). . FIG. 1 also shows a schematic diagram of a product in each step. Hereinafter, the BNNT material of the present invention and the process of its manufacturing method will be described with reference to the drawings.
　始めに、ＢＮＮＴ成長工程（Ｓ１）について説明する。図１３はＩＣＰ装置の一例を示す模式図である。図１３に示すように、ＩＣＰ装置２０は、プラズマを発生するプラズマトーチ２１と、ＢＮＮＴ原料とプラズマとを反応させる反応容器２２と、ＢＮＮＴ材料を回収するサイクロン２３と、ＢＮＮＴ材料以外（未反応の原料等）を回収するフィルター２４を備えている。ＢＮＮＴ成長工程（Ｓ１）では、まずＩＣＰ装置２０の反応容器２２の内部をプラズマガスでパージする。次に、プラズマトーチ２１によって反応容器２２内にプラズマを発生させる。プラズマガスとしては、特に限定は無いが、アルゴン（Ａｒ）、ヘリウム（Ｈｅ）、水素（Ｈ２）、窒素（Ｎ２）又はこれらの混合ガスが好ましい。 First, the BNNT growing step (S1) will be described. FIG. 13 is a schematic diagram illustrating an example of an ICP device. As shown in FIG. 13, the ICP apparatus 20 includes a plasma torch 21 for generating plasma, a reaction vessel 22 for reacting the BNNT raw material with the plasma, a cyclone 23 for recovering the BNNT material, And a filter 24 for collecting raw materials and the like. In the BNNT growth step (S1), first, the inside of the reaction vessel 22 of the ICP apparatus 20 is purged with a plasma gas. Next, plasma is generated in the reaction vessel 22 by the plasma torch 21. The plasma gas is not particularly limited, but is preferably argon (Ar), helium (He), hydrogen (H 2 ), nitrogen (N 2 ), or a mixed gas thereof.
　プラズマ生成中に、中心ガス、シースガス、原料ガス及び粉末キャリアガスの全ガス流がトーチに供給される。シースガスの主な目的は、プラズマを安定化させることである。シースガスとして、アルゴン、窒素及び水素の混合ガスを用いることが好ましい。原料粉末は、六方晶窒化ホウ素（ｈ－ＢＮ）粉末を用いることが好ましい。ｈ－ＢＮ粉末は、例えば、フィーダ（図１には示していない）によって供給量を制御し、キャリアガス（Ａｒ等）によってプラズマトーチに供給することができる。ｈ－ＢＮ粉末の平均粒径は、１～２０μｍ（１μｍ以上２０μｍ以下）が好ましい。１μｍ未満であると、ｈ－ＢＮ粉末供給時にフィーダに付着し、供給量が不安定になったり、キャリアライン（供給ライン）の詰まりを起こす可能性がある。一方、２０μｍより大きいと、プラズマによる分解が不完全となる恐れがあり、全体の効率を低下させる可能性がある。 During plasma generation, all gas flows of center gas, sheath gas, source gas and powder carrier gas are supplied to the torch. The main purpose of the sheath gas is to stabilize the plasma. It is preferable to use a mixed gas of argon, nitrogen and hydrogen as the sheath gas. It is preferable to use hexagonal boron nitride (h-BN) powder as the raw material powder. The h-BN powder can be supplied to the plasma torch by, for example, controlling the supply amount by a feeder (not shown in FIG. 1) and using a carrier gas (Ar or the like). The average particle size of the h-BN powder is preferably 1 to 20 μm (1 μm or more and 20 μm or less). If it is less than 1 μm, it may adhere to the feeder when the h-BN powder is supplied, causing an unstable supply amount or clogging of a carrier line (supply line). On the other hand, if it is larger than 20 μm, decomposition by plasma may be incomplete, and the overall efficiency may be reduced.
　ＢＮＮＴ成長工程（Ｓ１）では、図１の模式図に示すように、上述したｈ－ＢＮ粉末及び窒素ガスの化学反応から、繊維状のＢＮＮＴ１及びホウ素粒子２が形成される。そして、ホウ素粒子２は、拡大図に示すように、表面に窒化ホウ素フラーレン３を生成した生成物、すなわち窒化ホウ素フラーレン粒子（以下、ＢＮフラーレン粒子とも称する。）４となる。窒化ホウ素フラーレンとは、Ｂ原子とＮ原子が交互に結合したグラフェン構造を有し、球状又は長球状に閉じた構造を有するものを意味する。そして、この単体のＢＮフラーレン粒子４をＢＮＮＴ１の間に分散して混在させている（ばらばらに存在させる）。これによりＢＮＮＴのバンドル化を抑制することができ、ＢＮＮＴ１が分散し易くなる。即ち、ＢＮＮＴ材料は、数本から数十本のＢＮＮＴが束になって、いわゆるバンドル化して存在しており、バンドルは他のバンドルと複雑に絡み合っているのが一般的である。しかしながら、ＢＮフラーレン粒子４がＢＮＮＴ１の表面に、ファンデルワールス引力で付着することにより、上記ＢＮフラーレン粒子４を、バンドル内のＢＮＮＴ１の間に適宜介在させることになる。このＢＮフラーレン粒子４が物理的な立体障害となってＢＮＮＴのバンドル化を防ぎ、ＢＮＮＴが分散し易くなり、ＢＮＮＴのバンドル化を低減することができる。このようにＢＮＮＴ材料の合成段階の早い製造過程でバンドル化を抑制できるので、結果的にバンドル化が最小限に抑制されたＢＮＮＴ材料を得ることができる。 In the BNNT growth step (S1), as shown in the schematic diagram of FIG. 1, fibrous BNNT1 and boron particles 2 are formed from the above-described chemical reaction between the h-BN powder and nitrogen gas. Then, as shown in the enlarged view, the boron particles 2 become a product in which boron nitride fullerene 3 is generated on the surface, that is, boron nitride fullerene particles (hereinafter, also referred to as BN fullerene particles) 4. Boron nitride fullerene refers to a material having a graphene structure in which B atoms and N atoms are alternately bonded, and having a structure closed spherically or oblong. The single BN fullerene particles 4 are dispersed and mixed between the BNNTs 1 (distributedly exist). Thereby, bundling of BNNT can be suppressed, and BNNT1 is easily dispersed. That is, the BNNT material is present in what is called a bundle of several to several tens of BNNTs in a bundle, and the bundle is generally intricately intertwined with other bundles. However, the BN fullerene particles 4 adhere to the surface of the BNNT 1 by the van der Waals attractive force, so that the BN fullerene particles 4 are appropriately interposed between the BNNTs 1 in the bundle. The BN fullerene particles 4 prevent physical steric hindrance and prevent BNNTs from being bundled, so that BNNTs can be easily dispersed and BNNTs can be less bundled. As described above, the bundling can be suppressed in the manufacturing process at the early stage of the synthesis of the BNNT material, and as a result, the BNNT material with the bundling suppressed to a minimum can be obtained.
　また、本発明では、ＢＮフラーレン粒子４を核としてＢＮフラーレン３の表面からＢＮＮＴが成長し延出した成長体を有する生成物（以下、「成長体付きＢＮフラーレン粒子４ｂ」と称する。）を形成してもよい。この場合、ＢＮフラーレン粒子４は、成長体を有しないＢＮフラーレン粒子４ａ（以下、単に「ＢＮフラーレン粒子」あるいは、特に区別して呼びたいときに「単体のＢＮフラーレン粒子」と称することがある。）と、成長体付きＢＮフラーレン粒子４ｂとを含む態様がある。この態様では、成長体付きＢＮフラーレン粒子４ｂを、単体のＢＮフラーレン粒子４ａと共にＢＮＮＴ１の間に分散して混在させて（ばらばらに存在させて）いてもよい。単体のＢＮフラーレン粒子４ａと共に成長体付きＢＮフラーレン粒子４ｂもバンドル内のＢＮＮＴ１の間に介在することにより、これらが物理的な立体障害となって、ＢＮＮＴが分散し易くなり、ＢＮＮＴのバンドル化を低減することができる。 Further, in the present invention, a product having a growth body in which BNNT grows and extends from the surface of the BN fullerene 3 with the BN fullerene particle 4 as a nucleus (hereinafter, referred to as a “BN fullerene particle with growth body 4b”) is formed. May be. In this case, the BN fullerene particles 4 may be referred to as BN fullerene particles 4a having no growth body (hereinafter, may be simply referred to as “BN fullerene particles” or “single BN fullerene particles” when particularly distinguished.). And a BN fullerene particle 4b with a growth body. In this embodiment, the BN fullerene particles 4b with the growth body may be dispersed and mixed (present separately) between the BNNTs 1 together with the single BN fullerene particles 4a. Since the BN fullerene particles 4a with the growth body are also interposed between the BN fullerene particles 4a and the single BN fullerene particles 4a between the BNNTs 1 in the bundle, the BN fullerene particles 4b serve as a physical steric hindrance, so that the BNNTs are easily dispersed and the BNNTs are bundled. Can be reduced.
　また、本発明では、ＢＮフラーレン粒子４ａおよび成長体付きＢＮフラーレン粒子４ｂが生成されるにあたり、ＢＮＮＴを一部のＢＮフラーレン粒子だけから成長させ、他のＢＮフラーレン粒子はＢＮＮＴを成長させないことで、多数のＢＮフラーレン粒子４ａと少数の成長体付きＢＮフラーレン粒子４ｂとの混合物に形成して、これらをＢＮＮＴ１の間に分散して混在させることもできる。なお、成長体付きＢＮフラーレン粒子４ｂによるバンドル化の低減効果は単体のＢＮフラーレン粒子４ａほどではないと推察されるので、成長体付きＢＮフラーレン粒子４ｂの数は少ない方がよいと考えている。 Further, in the present invention, when the BN fullerene particles 4a and the BN fullerene particles with growth bodies 4b are generated, BNNT is grown from only some BN fullerene particles, and other BN fullerene particles are not grown. It is also possible to form a mixture of a large number of BN fullerene particles 4a and a small number of BN fullerene particles with growth 4b, and disperse and mix them between the BNNTs 1. Since it is assumed that the effect of reducing the bundling by the BN fullerene particles 4b with the growing body is not as large as that of the single BN fullerene particles 4a, it is considered that the smaller the number of the BN fullerene particles 4b with the growing body is, the better.
　ここで、ＢＮＮＴ１やＢＮフラーレン粒子４ａを形成するためには、プラズマトーチに印加する電力（プラズマパワー）を調整する。即ち、プラズマの２７００℃（窒化ホウ素の融点に相当）より高温の領域を出来るだけ長くするようにプラズマパワーを調整する。また、後述するＢＮフラーレン中空粒子の分散度は、この段階のＢＮフラーレン粒子の分散度に由来するところが大きい。従って、この段階でＢＮフラーレン粒子をＢＮＮＴ間に一様に分散させることが重要である。その為にはＢＮＮＴ成長工程で、例えば、全ガス流が乱流になることなく、層流になる条件を選定し、ＢＮフラーレン粒子が、ある程度揃った大きさで、一定量以上に形成されることが望ましい。 Here, in order to form the BNNT1 and the BN fullerene particles 4a, the power (plasma power) applied to the plasma torch is adjusted. That is, the plasma power is adjusted so that the region where the temperature of the plasma is higher than 2700 ° C. (corresponding to the melting point of boron nitride) is made as long as possible. The degree of dispersion of the BN fullerene hollow particles to be described later largely depends on the degree of dispersion of the BN fullerene particles at this stage. Therefore, at this stage, it is important to uniformly disperse the BN fullerene particles between the BNNTs. For this purpose, in the BNNT growth step, for example, a condition in which the entire gas flow becomes laminar without being turbulent is selected, and the BN fullerene particles are formed to have a uniform size to some extent and a certain amount or more. It is desirable.
　図２は、ＢＮＮＴ成長工程によって得られた生成物の低倍率の透過型電子顕微鏡（Ｔｒａｎｓｍｉｓｓｉｏｎ　Ｅｌｅｃｔｒｏｎ　Ｍｉｃｒｏｓｃｏｐｅ；ＴＥＭ）写真である。図２に示すように、ＢＮＮＴ１０１と、ＢＮフラーレン粒子１０２を有している。図２は低倍率のため図示されていないが、ＢＮフラーレン粒子１０２の中には、単体のＢＮフラーレン粒子と成長体付きＢＮフラーレン粒子とを含んでいる。ＢＮＮＴ１０１は、細く見える生成物１０１ａと太く見える生成物１０１ｂが混在しているが、太く見える生成物１０１ｂはファンデルワールス引力によりバンドル化したＢＮＮＴである（例えば、後述する図７を参照）。本発明のＢＮＮＴ材料は、上述したように、ＢＮフラーレン粒子の存在によりバンドル化が抑制されていることが分かる。なお、図２では、ＢＮフラーレン粒子１０２の平均粒子径は５ｎｍ～１００ｎｍであった。 FIG. 2 is a low magnification transmission electron microscope (TEM) photograph of the product obtained by the BNNT growth step. As shown in FIG. 2, it has BNNT101 and BN fullerene particles 102. Although not shown in FIG. 2 because of low magnification, the BN fullerene particles 102 include a single BN fullerene particle and a BN fullerene particle with a growth body. In the BNNT 101, a product 101a that looks thin and a product 101b that looks thick are mixed, but the product 101b that looks thick is a BNNT bundled by van der Waals attraction (for example, see FIG. 7 described later). It can be seen that the BNNT material of the present invention suppresses bundling due to the presence of BN fullerene particles, as described above. In FIG. 2, the average particle diameter of the BN fullerene particles 102 was 5 nm to 100 nm.
　ＢＮフラーレン粒子４（単体のＢＮフラーレン粒子４ａおよび成長体付きＢＮフラーレン粒子４ｂを含む。以下同様。）の平均粒子径は、１００ｎｍより大きくすると、ＢＮＮＴを分散させる効果が低減する。また、ＢＮフラーレン粒子の平均粒子径は、小さくするほど、少量でＢＮＮＴを分散させる効果が得られるが、５ｎｍよりも小さくすることは困難である。したがって、ＢＮフラーレン粒子の平均粒径は、５ｎｍ以上１００ｎｍ以下の範囲が好ましく、５ｎｍ以上３０ｎｍ以下の範囲がより好ましい。このようにすることにより、ＢＮＮＴが分散しバンドル化が最小限に抑制されたＢＮＮＴ材料を得ることができる。なお、ＢＮフラーレン粒子の平均粒径は、ＩＣＰの成長条件（原料ガスの流量及び原料の供給速度）により制御することが可能である。また、後述するＢＮフラーレン中空粒子（単体のＢＮフラーレン中空粒子７ａおよび成長体付きＢＮフラーレン中空粒子７ｂを含む。以下同様。）の平均粒径についても、同様に、５ｎｍ以上１００ｎｍ以下の範囲が好ましく、５ｎｍ以上３０ｎｍ以下の範囲がより好ましい。 When the average particle diameter of the BN fullerene particles 4 (including the single BN fullerene particles 4a and the BN fullerene particles with growth bodies 4b) is larger than 100 nm, the effect of dispersing the BNNTs is reduced. Further, as the average particle diameter of the BN fullerene particles decreases, the effect of dispersing BNNT in a small amount can be obtained, but it is difficult to reduce the average particle diameter to less than 5 nm. Therefore, the average particle size of the BN fullerene particles is preferably in the range of 5 nm to 100 nm, more preferably in the range of 5 nm to 30 nm. By doing so, it is possible to obtain a BNNT material in which BNNTs are dispersed and bundling is minimized. The average particle size of the BN fullerene particles can be controlled by ICP growth conditions (flow rate of raw material gas and supply speed of raw material). Similarly, the average particle size of the BN fullerene hollow particles (including the single BN fullerene hollow particles 7a and the grown BN fullerene hollow particles 7b with a growth body, hereinafter the same) is preferably in the range of 5 nm to 100 nm. The range is more preferably from 5 nm to 30 nm.
　図３は、ＢＮＮＴ成長工程によって得られた生成物に含まれるＢＮＮＴの高倍率の透過型電子顕微鏡写真である。図３では、ＢＮＮＴは、２層のＢＮＮＴ２０１と３層のＢＮＮＴ２０２が含まれていた。 FIG. 3 is a high magnification transmission electron micrograph of BNNT contained in the product obtained by the BNNT growth step. In FIG. 3, the BNNT includes two layers of BNNT201 and three layers of BNNT202.
　本発明により製造したＢＮＮＴ材料を観察した結果、２層以上４層以下のＢＮＮＴが全体の６０％程度であり、それ以外に、単層及び５層以上のＢＮＮＴが含まれていた。なお、ＢＮＮＴの層の数は、２層以上５層以下にすることが好ましく、ＢＮＮＴの層の数を少なくするほど、少量の添加で複合材料の引張強さやヤング率等の機械的強度を向上させることができる。ＢＮフラーレン粒子および後述するＢＮフラーレン中空粒子も多層構造を有しており、これらについても、ＢＮＮＴと同様に、２層以上５層以下にすることが好ましい。層の数は、ＩＣＰの成長条件（例えば、プラズマ領域の長さ）を変更することによって増減することが出来る。 観 察 As a result of observing the BNNT material manufactured according to the present invention, about 2% to 4 layers of BNNT accounted for about 60% of the whole, and in addition, a single layer and 5 layers or more of BNNT were included. The number of BNNT layers is preferably 2 or more and 5 or less. As the number of BNNT layers is reduced, the mechanical strength such as tensile strength and Young's modulus of the composite material is improved by adding a small amount. Can be done. The BN fullerene particles and the BN fullerene hollow particles described below also have a multilayer structure, and it is preferable that the number of these layers is two or more and five or less as in the case of BNNT. The number of layers can be increased or decreased by changing the growth conditions of the ICP (eg, the length of the plasma region).
　また、図３の顕微鏡写真では、ＢＮＮＴの平均直径は４ｎｍ以上６ｎｍ以下の範囲であった。ＢＮＮＴは、平均直径を５０ｎｍより大きくすると、ＢＮフラーレン粒子に対して大きくなり過ぎて剛性が増し、分散効果が低減する。また、平均直径は、小さいほど少量で高い分散効果が得られるが、１ｎｍよりも小さいＢＮＮＴを作製することは物理的にも困難である。従って、ＢＮＮＴは、１ｎｍ以上５０ｎｍ以下の平均直径に成長させることが好ましい。より好ましくは１ｎｍ以上２５ｎｍ以下であり、さらに好ましくは１ｎｍ以上１０ｎｍ以下である。ＢＮＮＴの平均直径は、ＩＣＰの成長条件（プラズマガスの流量及び原料の供給速度）により制御することが可能である。 In the micrograph of FIG. 3, the average diameter of BNNT was in the range of 4 nm to 6 nm. When the average diameter of BNNT is larger than 50 nm, the BNNT becomes too large with respect to the BN fullerene particles to increase rigidity and reduce the dispersion effect. Further, as the average diameter is smaller, a higher dispersion effect can be obtained with a smaller amount, but it is physically difficult to produce a BNNT smaller than 1 nm. Therefore, BNNT is preferably grown to an average diameter of 1 nm or more and 50 nm or less. The thickness is more preferably 1 nm or more and 25 nm or less, and further preferably 1 nm or more and 10 nm or less. The average diameter of BNNT can be controlled by ICP growth conditions (flow rate of plasma gas and supply rate of raw material).
　ＢＮフラーレン粒子の平均粒子径及びＢＮＮＴの平均直径は、走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ　Ｅｌｅｃｔｒｏｎ　Ｍｉｃｒｏｓｃｏｐｅ：ＳＥＭ）又はＴＥＭの観察写真で多数のＢＮフラーレン粒子の粒子径、及びＢＮＮＴの直径を直接測長し（例えば３０個）、これら測長値の算術平均により得ることができる。 The average particle diameter of the BN fullerene particles and the average diameter of the BNNT can be determined by directly measuring the particle diameters of a large number of BN fullerene particles and the diameter of the BNNT on a scanning electron microscope (Scanning Electron Microscope: SEM) or an TEM observation photograph ( (For example, 30), and can be obtained by arithmetic mean of these measured values.
　図４は、ＢＮＮＴ成長工程によって得られた生成物に含まれるＢＮフラーレン粒子の高倍率の透過型電子顕微鏡写真である。図４に示すように、ホウ素粒子３０１の表面は多層構造のＢＮフラーレン３０２に覆われており、さらに、ＢＮフラーレン３０２の表面には、Ｎ、Ｂ及びＨ（水素）を含むアモルファス成分３０３が付着している。ＢＮフラーレンは、電子線回折によって同定することが可能である。また、アモルファス成分は、エネルギー分散型Ｘ線分析（Ｅｎｅｒｇｙ　Ｄｉｓｐｅｒｓｉｖｅ　Ｘ－ｒａｙ　ｓｐｅｃｔｒｏｍｅｔｒｙ：ＥＤＸ）によって同定することが可能である。 FIG. 4 is a high magnification transmission electron micrograph of BN fullerene particles contained in the product obtained by the BNNT growth step. As shown in FIG. 4, the surface of the boron particles 301 is covered with a BN fullerene 302 having a multilayer structure, and an amorphous component 303 containing N, B and H (hydrogen) adheres to the surface of the BN fullerene 302. are doing. BN fullerene can be identified by electron diffraction. The amorphous component can be identified by energy dispersive X-ray analysis (Energy @ Dispersive @ X-ray @ spectrometry: EDX).
　このＢＮＮＴ材料において、ＢＮフラーレン粒子とＢＮＮＴの比表面積の比率を１：１０～１０：１の範囲内で、ほぼ同程度とすることが望ましい。ＢＮフラーレン粒子の比表面積に対するＢＮＮＴの比表面積は、１０倍より大きいと、ＢＮＮＴが分散しにくくなる。また、０．１倍より小さいと、ＢＮＮＴ材料に対するＢＮＮＴの量が十分ではなくなる。したがって、ＢＮＮＴの比表面積は、ＢＮフラーレン粒子の比表面積の０．１倍以上１０倍以下にすることが好ましい。このようにすることにより、ＢＮフラーレン粒子がＢＮＮＴの間に分散してバンドル化が最小限に抑制されたＢＮＮＴ材料を得やすい。尚、ＢＮＮＴの比表面積はおよそ２００～４００ｍ２／ｇの範囲とすることが好ましいが、比表面積の制御が困難な場合は、ＢＮＮＴに対するＢＮフラーレン粒子の量を制御して代えることができる。 In this BNNT material, it is desirable that the ratio of the specific surface area of the BN fullerene particles to the BNNT is approximately the same within a range of 1:10 to 10: 1. When the specific surface area of BNNT is more than 10 times the specific surface area of the BN fullerene particles, the BNNT becomes difficult to disperse. On the other hand, if it is smaller than 0.1 times, the amount of BNNT with respect to the BNNT material becomes insufficient. Therefore, it is preferable that the specific surface area of BNNT be 0.1 to 10 times the specific surface area of the BN fullerene particles. By doing so, the BN fullerene particles are dispersed between the BNNTs, and it is easy to obtain a BNNT material in which bundling is minimized. The specific surface area of BNNT is preferably in the range of about 200 to 400 m 2 / g. However, when it is difficult to control the specific surface area, the amount of BN fullerene particles with respect to BNNT can be controlled and replaced.
　なお、上記の好ましい範囲は、ＢＮＮＴ材料において、ＢＮフラーレン粒子の比表面積を、ＢＮフラーレン中空粒子の比表面積に置き換えて適用することができる。即ち、以下で述べる酸化熱処理工程後のホウ素成分が除去されたＢＮフラーレン中空粒子を用いて測定するものである。また、ＢＮＮＴ及びＢＮフラーレン中空粒子の比表面積は、ＢＥＴ（Ｂｒｕｎａｕｅｒ－Ｅｍｍｅｔｔ－Ｔｅｌｌｅｒ）法のような、ガス吸着法により測定（例えば、装置はＭｉｃｒｏｔｒａｃＢＥＬ社のＢＥＬＳＯＲＰ－ｍａｘＩＩ）することができる。 The above preferred range can be applied by replacing the specific surface area of the BN fullerene particles with the specific surface area of the BN fullerene hollow particles in the BNNT material. That is, the measurement is performed using BN fullerene hollow particles from which the boron component has been removed after the oxidation heat treatment step described below. The specific surface area of BNNT and BN fullerene hollow particles can be measured by a gas adsorption method such as a BET (Brunauer-Emmett-Teller) method (for example, BELSORP-maxII manufactured by Microtrac BEL).
　次に、酸化熱処理工程（Ｓ２）について説明する。酸化熱処理工程（Ｓ２）では、ＢＮＮＴ成長工程（Ｓ１）で得られた第１の生成物（以下、「第１の生成物」と称する。）に含まれるＢＮフラーレン粒子４のホウ素粒子２を酸化させて酸化ホウ素（Ｂ２Ｏ３）にする。酸化処理は、大気中、４５０℃以上１０００℃以下の温度により、３時間以上の熱処理とすることが好ましい。加熱温度が高いほど、この熱処理時間は短くすることが出来る。なお、加熱温度が４５０℃未満ではホウ素粒子が酸化され難いし、処理時間が長くなるため好ましくない。一方、１０００℃を超えるとＢＮＮＴが燃焼してしまい収率が低下するため好ましくない。より好ましくは５００℃以上９００℃以下、さらに好ましくは６００℃以上９００℃以下であり、最も好ましくは７００℃以上９００℃以下である。８００℃の場合で、処理時間は３時間あればホウ素粒子を酸化させて酸化ホウ素（Ｂ２Ｏ３）にするのに十分である。このような熱処理をすることにより、ホウ素粒子２を酸化ホウ素粒子６にすると共に、ＢＮフラーレン粒子４の表面に付着したアモルファス成分（Ｎ、Ｈ）を酸化させて消失させることができる。その結果、ＢＮＮＴ材料の純度を高めることができる。また、この酸化熱処理工程では、成長体付きＢＮフラーレン粒子４ｂについても、同様にホウ素粒子を酸化ホウ素粒子にすることができる。 Next, the oxidation heat treatment step (S2) will be described. In the oxidation heat treatment step (S2), the boron particles 2 of the BN fullerene particles 4 contained in the first product (hereinafter, referred to as “first product”) obtained in the BNNT growth step (S1) are oxidized. To form boron oxide (B 2 O 3 ). The oxidation treatment is preferably performed in air at a temperature of 450 ° C. or more and 1000 ° C. or less for 3 hours or more. The higher the heating temperature, the shorter the heat treatment time. If the heating temperature is lower than 450 ° C., the boron particles are not easily oxidized, and the processing time is undesirably long. On the other hand, if the temperature exceeds 1000 ° C., BNNT is burned and the yield is undesirably reduced. The temperature is more preferably from 500 ° C to 900 ° C, further preferably from 600 ° C to 900 ° C, and most preferably from 700 ° C to 900 ° C. At 800 ° C., a treatment time of 3 hours is sufficient to oxidize the boron particles to boron oxide (B 2 O 3 ). By performing such a heat treatment, the boron particles 2 can be converted into the boron oxide particles 6, and the amorphous components (N, H) attached to the surfaces of the BN fullerene particles 4 can be oxidized and eliminated. As a result, the purity of the BNNT material can be increased. Also, in this oxidation heat treatment step, the boron particles can be similarly changed to boron oxide particles for the BN fullerene particles 4b with the grown body.
　次に、酸化物除去工程（Ｓ３）について説明する。酸化物除去工程（Ｓ３）では、酸化処理工程（Ｓ２）で生成した酸化ホウ素（Ｂ２Ｏ３）を、例えば洗浄液によって溶解して除去し、ＢＮフラーレン３を外層とし、ＢＮＮＴの成長体を有しないＢＮフラーレン中空粒子７（以下、「ＢＮフラーレン中空粒子」と称する。）を形成する。これによって、ＢＮＮＴ１の間に、少なくともこのＢＮフラーレン中空粒子７が分散された第２の生成物を得る。第２の生成物は、より高純度化されており、上記ＢＮフラーレン中空粒子７をバンドル内のＢＮＮＴ１の間に適宜介在させることにより、ＢＮＮＴ１が分散し易くなり、バンドル化が最小限に抑制された高純度のＢＮＮＴ材料とすることができる。なお、ＢＮフラーレン中空粒子７によってバンドル化を低減することができるメカニズムや効果は、上述したＢＮフラーレン粒子４のそれと同様であるので説明は省略する。 Next, the oxide removing step (S3) will be described. In the oxide removal step (S3), the boron oxide (B 2 O 3 ) generated in the oxidation treatment step (S2) is removed by, for example, dissolving with a cleaning solution, and the BN fullerene 3 is used as an outer layer, and the BNNT growth is present. BN fullerene hollow particles 7 (hereinafter referred to as “BN fullerene hollow particles”) are formed. Thereby, a second product in which at least the BN fullerene hollow particles 7 are dispersed between the BNNTs 1 is obtained. The second product is further purified, and by appropriately interposing the BN fullerene hollow particles 7 between the BNNTs 1 in the bundle, the BNNTs 1 are easily dispersed and the bundling is minimized. High purity BNNT material. The mechanism and effect of reducing the bundling by the BN fullerene particles 7 are the same as those of the BN fullerene particles 4 described above, and thus the description is omitted.
　また、ＢＮＮＴ成長工程にて形成した生成物が、ＢＮフラーレン粒子４ａと成長体付きＢＮフラーレン粒子４ｂの混合物の場合には、成長体付きＢＮフラーレン粒子４ｂに含まれる酸化ホウ素（Ｂ２Ｏ３）も同様に除去し、中空状の粒子の表面からＢＮＮＴが成長し延出した、成長体を有するＢＮフラーレン中空粒子７ｂ（以下、「成長体付きＢＮフラーレン中空粒子」と称する。）を分散させて含ませることもできる。この場合は、単体のＢＮフラーレン中空粒子７ａと、成長体付きＢＮフラーレン中空粒子７ｂとが混合した、高純度のＢＮＮＴ材料１０を得ることもできる。尚、洗浄液としては、Ｂ２Ｏ３を溶解できる物であれば特に限定は無いが、エタノール、メタノール又は水が好ましい。また、ここで超音波洗浄処理を用いることにより、洗浄除去と共にＢＮフラーレン中空粒子の分散度をある程度改善することができる。以下、酸化熱処理工程（Ｓ２）及び酸化物除去工程（Ｓ３）を合わせて「高純度化工程」とも称する。 When the product formed in the BNNT growth step is a mixture of the BN fullerene particles 4a and the BN fullerene particles 4b with the growing body, the boron oxide (B 2 O 3 ) contained in the BN fullerene particles with the growing body 4b is included. The BN fullerene hollow particles 7b (hereinafter, referred to as “growth-bearing BN fullerene hollow particles”) having growth bodies, in which BNNTs have grown and extended from the surfaces of the hollow particles, are dispersed in the same manner. It can also be included. In this case, a high-purity BNNT material 10 in which a single BN fullerene hollow particle 7a and a grown BN fullerene hollow particle 7b are mixed can be obtained. The washing liquid is not particularly limited as long as it can dissolve B 2 O 3 , but ethanol, methanol or water is preferable. Further, by using the ultrasonic cleaning treatment here, the degree of dispersion of the BN fullerene hollow particles can be improved to some extent together with the cleaning and removal. Hereinafter, the oxidation heat treatment step (S2) and the oxide removal step (S3) are also collectively referred to as a “purification step”.
　図５Ａは、高純度化工程前（ＢＮＮＴ成長工程後）の第１の生成物の低倍率の透過型電子顕微鏡写真であり、図５Ｂは、高純度化工程後の第２の生成物の低倍率の透過型電子顕微鏡写真である。第１の生成物のＢＮフラーレン粒子と第２の生成物のＢＮフラーレン中空粒子は、共にＢＮＮＴの間に分散されていることが分かる。そして、図５Ａ及び図５Ｂの比較から分かるように、酸化熱処理工程（Ｓ２）及び酸化物除去工程（Ｓ３）後は、ＢＮフラーレン粒子４からホウ素成分が除去され、ホウ素粒子の表面を覆うＢＮフラーレンのみが残り、ＢＮフラーレン中空粒子４０１を形成している。なお、ホウ素成分を完全に除去することは困難である為、図５Ｂのように空洞部分が確認できればＢＮフラーレン中空粒子とみなすものとする。 FIG. 5A is a low magnification transmission electron micrograph of the first product before the purification step (after the BNNT growth step), and FIG. 5B is a low-resolution transmission electron micrograph of the second product after the purification step. It is a transmission electron micrograph of magnification. It can be seen that the BN fullerene particles of the first product and the BN fullerene hollow particles of the second product are both dispersed between BNNTs. 5A and 5B, after the oxidation heat treatment step (S2) and the oxide removal step (S3), the boron component is removed from the BN fullerene particles 4, and the BN fullerene covering the surface of the boron particles is removed. Only the remaining BN fullerene hollow particles 401 are formed. Since it is difficult to completely remove the boron component, if a hollow portion can be confirmed as shown in FIG. 5B, it is regarded as BN fullerene hollow particles.
　以上の高純度化工程により、Ｎ及びＨを含むアモルファス成分も燃焼除去されるため、最終的には、上述したようにＢＮＮＴとＢＮフラーレン中空粒子とが混合したＢＮＮＴ材料、あるいはＢＮＮＴとＢＮフラーレン中空粒子及び成長体付きＢＮフラーレン中空粒子とが混合したＢＮＮＴ材料を得ることができる。 By the above-described high-purification step, the amorphous components containing N and H are also burned off, and finally, as described above, the BNNT material in which the BNNT and the BN fullerene hollow particles are mixed, or the BNNT material and the BN fullerene hollow A BNNT material in which the particles and the BN fullerene hollow particles with the growing body are mixed can be obtained.
　図６は、本発明の高分散化されたＢＮＮＴ材料を示す高倍率の透過型電子顕微鏡写真である。高分散化されたＢＮＮＴ材料では、ＢＮフラーレン粒子から形成されたＢＮフラーレン中空粒子５０２がＢＮＮＴ５０１と接触し、その間に介在していることにより、バンドル化が抑制されていることが分かる。図７は、ＢＮＮＴだけとした従来のＢＮＮＴ材料の高倍率の透過型電子顕微鏡写真である。複数のＢＮＮＴが重なり合いバンドルとバンドルの絡み合いが生じていることが分かる。図７に示すＢＮＮＴ材料は、ＢＮＮＴ材料からＢＮフラーレン中空粒子を除去して作製した物である。ＢＮＮＴ材料からのＢＮフラーレン中空粒子の除去は、例えば、遠心分離法等の分離技術を利用することが可能である。 FIG. 6 is a high magnification transmission electron micrograph showing the highly dispersed BNNT material of the present invention. In the highly dispersed BNNT material, it can be seen that the BN fullerene hollow particles 502 formed from the BN fullerene particles are in contact with the BNNT 501 and are interposed therebetween, whereby bundling is suppressed. FIG. 7 is a high magnification transmission electron micrograph of a conventional BNNT material using only BNNT. It can be seen that a plurality of BNNTs overlap and the bundles are entangled. The BNNT material shown in FIG. 7 is manufactured by removing BN fullerene hollow particles from the BNNT material. For the removal of the BN fullerene hollow particles from the BNNT material, for example, a separation technique such as a centrifugal separation method can be used.
　本発明のＢＮＮＴ材料と、その製造方法では、上述した通り、ＢＮＮＴの成長工程において、少なくともＢＮフラーレン粒子を形成し、高純度化工程においてＢＮフラーレン粒子からＢＮフラーレン中空粒子を形成する。そして、少なくともＢＮフラーレン中空粒子をＢＮＮＴ材料中に残すようにする。このようにすることで、ＢＮフラーレン中空粒子が多数のＢＮＮＴの間に分散されて、ＢＮＮＴが分散し易くなりバンドル化が抑制された、つまり高分散化されたＢＮＮＴ材料を得ることができる。なお、上述してきたように成長体付きＢＮフラーレン粒子も形成し、この成長体付きＢＮフラーレン粒子から成長体付きＢＮフラーレン中空粒子を形成し、これをＢＮフラーレン中空粒子と共にＢＮＮＴの中に分散混合させてＢＮＮＴ材料を得ることもできる。 In the BNNT material of the present invention and the method for producing the same, as described above, at least BN fullerene particles are formed in the BNNT growth step, and BN fullerene hollow particles are formed from the BN fullerene particles in the high-purification step. Then, at least the BN fullerene hollow particles are left in the BNNT material. By doing so, the BN fullerene hollow particles are dispersed between a large number of BNNTs, and the BNNTs are easily dispersed, and bundling is suppressed, that is, a highly dispersed BNNT material can be obtained. As described above, BN fullerene particles with growth bodies are also formed, and BN fullerene particles with growth bodies are formed from the BN fullerene particles with growth bodies, and the BN fullerene particles with growth bodies are dispersed and mixed together with the BN fullerene hollow particles in BNNT. To obtain a BNNT material.
　また、上述した説明の中で、ＢＮＮＴの比表面積は、ＢＮフラーレン粒子の比表面積の０．１倍以上１０倍以下となすこと、ＢＮフラーレン粒子及び成長体付きＢＮフラーレン粒子の平均粒子径は５ｎｍ以上１００ｎｍ以下が好ましいこと、ＢＮＮＴおよびＢＮフラーレン粒子が２層以上５層以下の多層構造を有していること、及びＢＮＮＴの平均直径が１ｎｍ以上５０ｎｍ以下であることが好ましいこと等を述べた。これらの形態は、ＢＮＮＴ成長工程～高純度化工程において基本的に維持されるので、これらの要件は、高純度化工程後に得られる最終のＢＮＮＴ材料でも備えている要件である。したがって、上述したＢＮフラーレン粒子はＢＮフラーレン中空粒子に、成長体付きＢＮフラーレン粒子は成長体付きＢＮフラーレン中空粒子にそのまま置き換えることが出来るので、その説明は省略する。 In the above description, the specific surface area of BNNT should be 0.1 to 10 times the specific surface area of the BN fullerene particles, and the average particle diameter of the BN fullerene particles and the BN fullerene particles with growth bodies is 5 nm. It has been described that the thickness is preferably 100 nm or less, that the BNNT and BN fullerene particles have a multilayer structure of 2 to 5 layers, and that the average diameter of the BNNT is preferably 1 nm to 50 nm. Since these forms are basically maintained in the BNNT growth step to the high-purification step, these requirements are also provided in the final BNNT material obtained after the high-purification step. Therefore, the above-described BN fullerene particles can be replaced with hollow BN fullerene particles, and the BN fullerene particles with growth bodies can be replaced with hollow BN fullerene particles with growth bodies, and the description thereof is omitted.
　なお、これまでＢＮＮＴ成長工程をＩＣＰを用いた場合について説明したが、ＩＣＰに代えて、レーザー気化、熱分解および直流プラズマを用いることもできる。 Although the case where ICP is used in the BNNT growth step has been described above, laser vaporization, thermal decomposition, and DC plasma can be used instead of ICP.
　［実施例１および比較例１～２のＢＮＮＴ材料の作製と評価］
　本実施例では、本発明のＢＮＮＴ材料（実施例１の試料）と、比較として、本発明のＢＮＮＴ材料からＢＮフラーレン中空粒子を除いて作製したＢＮＮＴ（比較例１の試料）を作製した。また、ＢＮＮＴ合成後にＢＮフラーレン中空粒子を添加してＢＮＮＴのバンドル化を抑制できるか否かを確認するため、ＢＮＮＴとＢＮフラーレン中空粒子を別々に用意して混合して作製したＢＮＮＴ材料（比較例２の試料）を作製した。以上の実施例１、比較例１、比較例２について、バンドル化の程度を評価した。 [Production and Evaluation of BNNT Materials of Example 1 and Comparative Examples 1 and 2]
In this example, a BNNT material of the present invention (sample of Example 1) and, as a comparison, a BNNT material (sample of Comparative Example 1) prepared by removing BN fullerene hollow particles from the BNNT material of the present invention. Further, in order to confirm whether or not BN fullerene hollow particles can be added to suppress the bundling of BNNT after BNNT synthesis, a BNNT material prepared by separately preparing and mixing BNNT and BN fullerene hollow particles (Comparative Example) 2 samples). The degree of bundling of the above Example 1, Comparative Example 1 and Comparative Example 2 was evaluated.
　実施例１のＢＮＮＴ材料は、以下の要領で作製した。プラズマ方式としては、小型プラズマ装置（ＴＥＫＮＡ　Ｐｌａｓｍａ　Ｓｙｓｔｅｍｓ　ｉｎｃ．製、型式：ＴｅｋＮａｎｏ－１５）を用いた。まず始めに、反応容器内をアルゴンガスでパージした。次に、中央領域にアルゴンガス(流速：１０Ｌ／ｍｉｎ)を流し、アルゴン（３０Ｌ／ｍｉｎ）と水素（２．５Ｌ／ｍｉｎ）の混合ガスを流すことにより、プラズマを閉じ込める管の外周にシースガスを流す。窒素ガスは、トーチノズル（１０Ｌ／ｍｉｎ）と反応容器を取り囲むポーラスウォール（４７Ｌ／ｍｉｎ）の両方を通して流される。プラズマ着火から数分後、反応容器とサイクロンの間に設置した熱電対の温度が一定温度になったところで、原材料であるｈ－ＢＮの粉末（５μｍ）をプラズマトーチの上部に設置したフィーダから、アルゴン（２．５Ｌ／ｍｉｎ）をキャリアガスとして連続供給した。供給速度は、０．５ｇ／ｍｉｎ、運転時間は２ｈｒで、反応チャンバ内の圧力は１ａｔｍとした。 Ｂ The BNNT material of Example 1 was produced in the following manner. As the plasma method, a small-sized plasma device (manufactured by TEKNA Plasma Systems Inc., model: TekNano-15) was used. First, the inside of the reaction vessel was purged with argon gas. Next, an argon gas (flow rate: 10 L / min) is caused to flow in the central region, and a mixed gas of argon (30 L / min) and hydrogen (2.5 L / min) is caused to flow. Shed. Nitrogen gas flows through both the torch nozzle (10 L / min) and the porous wall (47 L / min) surrounding the reaction vessel. A few minutes after the plasma ignition, when the temperature of the thermocouple installed between the reaction vessel and the cyclone reaches a constant temperature, the raw material h-BN powder (5 μm) is fed from the feeder installed on the upper part of the plasma torch. Argon (2.5 L / min) was continuously supplied as a carrier gas. The supply speed was 0.5 g / min, the operation time was 2 hr, and the pressure in the reaction chamber was 1 atm.
　ＢＮＮＴの成長（ＢＮＮＴ成長工程（Ｓ１））が終了した後、装置を分解して、プラズマトーチ、リアクタ、サイクロン及びフィルター部に付着した生成物を回収した。次に、回収した生成物を大気中、８００℃で３時間の酸化処理（酸化熱処理工程（Ｓ２））した後、エタノールを用いて洗浄し、酸化ホウ素等のホウ素成分を除去（酸化物除去工程（Ｓ３））して実施例１の試料を得た。得られたＢＮフラーレン中空粒子は、大部分が５～５０ｎｍの粒径範囲にあり平均粒子径は３０ｎｍであった。また、ＢＮＮＴは、層の数が２～４層のものが全体の６０％程度を占め、それらの直径は４～６ｎｍの範囲にあった。 After the growth of BNNT (the BNNT growth step (S1)) was completed, the apparatus was disassembled and the products adhered to the plasma torch, the reactor, the cyclone, and the filter were recovered. Next, the collected product is oxidized in air at 800 ° C. for 3 hours (oxidation heat treatment step (S2)), and then washed with ethanol to remove boron components such as boron oxide (oxide removal step). (S3)) to obtain a sample of Example 1. Most of the obtained BN fullerene hollow particles were in the particle size range of 5 to 50 nm, and had an average particle size of 30 nm. BNNTs having 2 to 4 layers accounted for about 60% of the total, and their diameters were in the range of 4 to 6 nm.
　上述した実施例１の試料を１時間の遠心分離処理を行い、ＢＮフラーレン中空粒子を除いた生成物を比較例１の試料とした。この試料では、図７に示すように複数のＢＮＮＴが重なり合いバンドルとバンドルの絡み合いが増していることが確認された。 (4) The sample of Example 1 was subjected to a centrifugal separation treatment for one hour, and the product obtained by removing the BN fullerene hollow particles was used as a sample of Comparative Example 1. In this sample, as shown in FIG. 7, it was confirmed that the plurality of BNNTs overlapped and the entanglement between the bundles increased.
　次に、実施例１の試料にＢＮフラーレン中空粒子を混合した生成物を比較例２の試料とした。この試料では、ＢＮＮＴは、既にお互いがファンデルワールス引力によりある程度のバンドルを形成しているため、これにＢＮフラーレン中空粒子を混合しても、そのバンドルをほぐすことができず、分散させる効果がないことが確認された。 Next, a product obtained by mixing BN fullerene hollow particles with the sample of Example 1 was used as a sample of Comparative Example 2. In this sample, BNNTs have already formed a certain amount of bundles due to van der Waals attractive force. Therefore, even if BN fullerene hollow particles are mixed with the BNNTs, the bundles cannot be loosened and the effect of dispersing them is not obtained. Not confirmed.
　また、実施例１及び比較例１について、バンドル化の程度を評価した。具体的には、実施例１及び比較例１の試料を０．１質量％含有するエタノール溶液を調製し、これをシリコンウエハの上にそれぞれ滴下して、エタノールが完全に蒸発した後、サンプルを分析した。このサンプルを原子力間顕微鏡（Ａｔｏｍｉｃ　Ｆｏｒｃｅ　Ｍｉｃｒｏｓｃｏｐｅ；ＡＦＭ）を用いて高さ分布を測定した。ＢＮＮＴがバンドル化しないで分散している場合、高さ分布は、ＢＮＮＴの直径近傍を中心としたピークを持つ分布になる。これに対して、バンドル化している場合、複数のＢＮＮＴに対応する高さを示すため、高さ分布は直径よりも大きな値となる。 In addition, the degree of bundling of Example 1 and Comparative Example 1 was evaluated. Specifically, an ethanol solution containing 0.1% by mass of the samples of Example 1 and Comparative Example 1 was prepared, and the solution was dropped on a silicon wafer, and after the ethanol was completely evaporated, the sample was removed. analyzed. The height distribution of this sample was measured using an atomic force microscope (Atomic Force Microscope; AFM). When the BNNTs are dispersed without being bundled, the height distribution becomes a distribution having a peak centered around the diameter of the BNNT. On the other hand, when bundled, the height distribution indicates a height corresponding to a plurality of BNNTs, so that the height distribution is a value larger than the diameter.
　図８は、実施例１のＡＦＭによる高さ分布測定結果を示すグラフである。ＡＦＭ測定は、コンタクトモードで行った。図８に示すように、透過型電子顕微鏡で測定したＢＮＮＴの平均直径６ｎｍ付近を中心に分布していることから、ＢＮフラーレン中空粒子がＢＮＮＴの間に分散していることによりＢＮＮＴが孤立化して分散していることがわかる。なお、ＢＮフラーレン中空粒子はＢＮＮＴ材料の中に分散して混在しているが、図８ではＢＮＮＴ材料に含まれるＢＮフラーレン中空粒子の測定結果は現れていない。これは、ＡＦＭ測定時にＢＮＮＴはファンデルワールス力でしっかり固定されているので測定可能であるが、ＢＮフラーレン中空粒子はＡＦＭ探針の接触で動いてしまい、ノイズとなって測定ができないためである。 FIG. 8 is a graph showing the results of height distribution measurement by the AFM of Example 1. The AFM measurement was performed in the contact mode. As shown in FIG. 8, BNNTs are distributed around a mean diameter of about 6 nm of the BNNTs measured by a transmission electron microscope, so that the BN fullerene hollow particles are dispersed between the BNNTs, so that the BNNTs are isolated. It can be seen that they are dispersed. Although the BN fullerene hollow particles are dispersed and mixed in the BNNT material, FIG. 8 does not show the measurement results of the BN fullerene hollow particles contained in the BNNT material. This is because BNNT is firmly fixed by van der Waals force during AFM measurement, but can be measured, but BN fullerene hollow particles move due to the contact of the AFM probe, resulting in noise that cannot be measured. .
　図９は、比較例１のＡＦＭによる高さ分布測定結果を示すグラフである。図９に示すように、比較例１の試料は、透過型電子顕微鏡で測定したＢＮＮＴの平均直径６ｎｍよりもかなり大きい１７ｎｍ付近を中心に分布していることから、ＢＮＮＴがバンドル化していることがわかる。 FIG. 9 is a graph showing the results of height distribution measurement by AFM of Comparative Example 1. As shown in FIG. 9, the sample of Comparative Example 1 is distributed around 17 nm, which is considerably larger than the average diameter of BNNT measured by a transmission electron microscope, which is 6 nm. Understand.
　図１０は、比較例２のＡＦＭによる高さ分布測定結果を示すグラフである。図１０に示すように、比較例２の試料も比較例１の試料と同様に、透過型電子顕微鏡で測定したＢＮＮＴの平均直径６ｎｍよりもかなり大きい１７ｎｍ付近を中心に分布していることから、ＢＮＮＴがバンドル化していることがわかる。 FIG. 10 is a graph showing the result of height distribution measurement by AFM of Comparative Example 2. As shown in FIG. 10, similarly to the sample of Comparative Example 1, the sample of Comparative Example 2 is distributed around 17 nm, which is considerably larger than the average diameter of BNNT measured by a transmission electron microscope, which is 6 nm. It can be seen that BNNT is bundled.
　実施例１及び比較例１の結果から、ＢＮフラーレン中空粒子を含んでいない状態ではＢＮＮＴのバンドル化を抑制できないことがわかった。また、実施例１及び比較例２の結果から、ＢＮＮＴの合成後にＢＮフラーレン中空粒子を混合してもＢＮＮＴのバンドル化を抑制できないことがわかった。すなわち、ＢＮＮＴの合成段階の初期でＢＮフラーレンを同時に生成させ分散させることにより、ＢＮＮＴが分散してバンドル化が抑制された高分散ＢＮＮＴ材料が得られることがわかった。 か ら From the results of Example 1 and Comparative Example 1, it was found that BNNT bundling could not be suppressed in the state where BN fullerene hollow particles were not included. Further, from the results of Example 1 and Comparative Example 2, it was found that even if BN fullerene hollow particles were mixed after the synthesis of BNNT, BNNT bundling could not be suppressed. That is, it was found that by simultaneously generating and dispersing BN fullerene in the early stage of the synthesis of BNNT, a highly dispersed BNNT material in which BNNT was dispersed and bundle formation was suppressed was obtained.
　［実施例２のＢＮＮＴ複合材料の作製と評価］
　実施例１の試料を用いて、母材をアルミニウムとするＢＮＮＴ複合材料を作製した。本発明のバンドル化が抑制され、高分散化されたＢＮＮＴ材料を用いて、金属複合材料や樹脂複合材料などの各種のＢＮＮＴ複合材料を作製することが可能である。本実施例では、ＢＮＮＴ複合材料として、ＢＮＮＴとアルミニウムの複合材料（ＢＮＮＴ／Ａｌ複合材料）と、ＢＮＮＴとフッ素樹脂の複合材料（ＢＮＮＴ／フッ素樹脂複合材料）を作製した。 [Production and evaluation of BNNT composite material of Example 2]
Using the sample of Example 1, a BNNT composite material using aluminum as a base material was produced. Various BNNT composite materials such as a metal composite material and a resin composite material can be manufactured using the highly dispersed BNNT material in which bundling of the present invention is suppressed. In this example, as a BNNT composite material, a composite material of BNNT and aluminum (BNNT / Al composite material) and a composite material of BNNT and fluororesin (BNNT / fluororesin composite material) were produced.
　ＢＮＮＴ／Ａｌ複合材料は、上記実施例１のＢＮＮＴ材料をアルミニウム溶湯中に投入し、これを凝固させて作製した。ＢＮＮＴ材料の含有量は５質量％である。図１１は、本発明のＢＮＮＴ材料を用いて作製したＢＮＮＴ／Ａｌ複合材料の表面の走査型電子顕微鏡写真である。図１１に示すように、ＢＮＮＴ９０１はアルミニウム母材の内部に潜り込んで表面がアルミナに覆われて、太く見える。 The BNNT / Al composite material was prepared by charging the BNNT material of Example 1 into a molten aluminum and solidifying the same. The content of the BNNT material is 5% by mass. FIG. 11 is a scanning electron micrograph of the surface of a BNNT / Al composite material produced using the BNNT material of the present invention. As shown in FIG. 11, BNNT901 sneaks into the aluminum base material, and the surface is covered with alumina, so that it looks thick.
　アルミニウムにＢＮＮＴ材料を混合していない試料と、上記したＢＮＮＴ／Ａｌ複合材料の試料をそれぞれ用意し、引張圧縮試験機テクノグラフ（ミネベアミツミ株式会社製、型式：ＴＧＩ－１０ｋＮ）を用いて引張強さを測定した。その結果、ＢＮＮＴ材料を混合していない試料が１６５ＭＰａであったのに対し、ＢＮＮＴ／Ａｌ複合材料は３５０ＭＰａとなり、高強度化することを確認できた。なお、金属複合材料の母材は、アルミニウムの他にチタン、ニッケル、鉄またはこれらの合金を用いることができる。 A sample in which the BNNT material was not mixed with aluminum and a sample of the BNNT / Al composite material described above were prepared, and tensile strength was measured using a tensile / compression testing machine Technograph (manufactured by MinebeaMitsumi Co., Ltd., model: TGI-10 kN). Was measured. As a result, while the sample in which the BNNT material was not mixed was 165 MPa, the BNNT / Al composite material became 350 MPa, and it was confirmed that the strength was increased. Note that as the base material of the metal composite material, titanium, nickel, iron, or an alloy thereof can be used in addition to aluminum.
　［実施例３のＢＮＮＴ複合材料の作製と評価］
　次に、母材をフッ素含有樹脂とするＢＮＮＴとフッ素樹脂の複合材料を作製した。
　ＢＮＮＴ／フッ素樹脂複合材料は、フッ素含有樹脂の有機溶液と、上記実施例１のＢＮＮＴ材料の有機溶液を混合し、その後、有機溶媒を乾燥除去することにより作製した。ＢＮＮＴ材料の含有量は５質量％である。 [Production and evaluation of BNNT composite material of Example 3]
Next, a composite material of BNNT and a fluororesin having a base material as a fluorine-containing resin was produced.
The BNNT / fluororesin composite material was prepared by mixing an organic solution of the fluorine-containing resin and the organic solution of the BNNT material of Example 1 described above, and then drying and removing the organic solvent. The content of the BNNT material is 5% by mass.
　図１２は、本発明のＢＮＮＴ材料を用いて作製したＢＮＮＴ／フッ素樹脂複合材料の表面の走査型電子顕微鏡写真である。図１２は、作製したＢＮＮＴ／フッ素樹脂複合材料を液体窒素中で凍結後、劈開した表面を走査型電子顕微鏡で観察したものである。図１２に示すように、ＢＮＮＴ／フッ素樹脂複合材料中のＢＮＮＴ１００１は、樹脂劈開表面から飛び出して見える。 FIG. 12 is a scanning electron micrograph of the surface of a BNNT / fluororesin composite material produced using the BNNT material of the present invention. FIG. 12 shows the BNNT / fluororesin composite material produced by freezing it in liquid nitrogen and observing the cleaved surface with a scanning electron microscope. As shown in FIG. 12, BNNT1001 in the BNNT / fluororesin composite material appears to jump out of the resin cleavage surface.
　フッ素含有樹脂にＢＮＮＴ材料を混合していない試料と、上記したＢＮＮＴ／フッ素樹脂複合材料の試料をそれぞれ用意し、熱膨張測定装置（ＮＥＴＺＳＣＨ製、型式：ＤＩＬ４０２）を用いて熱膨張率を測定した。その結果、ＢＮＮＴ／フッ素樹脂複合材料の試料の熱膨張率は、ＢＮＮＴ材料を含まない試料よりも３０％低くなった。本発明のＢＮＮＴ材料を用いた樹脂複合材料は、バンドル化を抑制したことによって、熱膨張率の低減などＢＮＮＴ材料の特性を十分に発揮できることが確認できた。なお、樹脂複合材料の母材は、フッ素樹脂の他に熱硬化性樹脂、熱可塑性樹脂、塩素、ヨウ素または臭素含有樹脂またはそれらの任意の混合物を用いることができる。 A sample in which the BNNT material was not mixed with the fluorine-containing resin and a sample of the BNNT / fluororesin composite material described above were prepared, and the coefficient of thermal expansion was measured using a thermal expansion measuring device (manufactured by NETZSCH, model: DIL402). . As a result, the coefficient of thermal expansion of the sample of the BNNT / fluororesin composite material was 30% lower than that of the sample containing no BNNT material. It was confirmed that the resin composite material using the BNNT material of the present invention can sufficiently exhibit the characteristics of the BNNT material, such as a reduction in the coefficient of thermal expansion, by suppressing bundling. In addition, as the base material of the resin composite material, a thermosetting resin, a thermoplastic resin, a chlorine, iodine or bromine-containing resin, or an arbitrary mixture thereof can be used in addition to the fluororesin.
　以上、説明したように、本発明によれば、ＢＮフラーレン中空粒子がＢＮＮＴの間に分散されることにより、ＢＮＮＴが分散してバンドル化が抑制されたＢＮＮＴ材料と、ＢＮＮＴ材料の製造方法、およびＢＮＮＴ材料を用いた高強度の複合材料や低熱膨張の複合材料を提供できることが実証された。 As described above, according to the present invention, the BN fullerene hollow particles are dispersed between the BNNTs, whereby the BNNT material is dispersed and the bundling is suppressed, and the method for producing the BNNT material, and It has been demonstrated that a high-strength composite material and a low-thermal-expansion composite material using a BNNT material can be provided.
　なお、本発明は上記した実施例に限定されるものではなく、様々な変形例が含まれる。例えば、上記した実施例は本発明を分かり易く説明するために詳細に説明したものであり、必ずしも説明した全ての構成を備えるものに限定されるものではない。また、ある実施例の構成の一部を他の実施例の構成に置き換えることが可能であり、ある実施例の構成に他の実施例の構成を加えることも可能である。また、各実施例の構成の一部について、他の構成の追加や削除または置換をすることが可能である。 The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. In addition, it is possible to add, delete, or replace another configuration with respect to a part of the configuration of each embodiment.
　１，１０１，１０１ａ，１０１ｂ，５０１…窒化ホウ素ナノチューブ、２，３０１…ホウ素粒子、３，３０２…窒化ホウ素フラーレン、４，１０２…窒化ホウ素フラーレン粒子、４ａ…窒化ホウ素フラーレン粒子、４ｂ…成長体付き窒化ホウ素フラーレン粒子、７…窒化ホウ素フラーレン中空粒子、７ａ…窒化ホウ素フラーレン中空粒子、７ｂ…成長体付き窒化ホウ素フラーレン中空粒子、４０１，５０２…窒化ホウ素フラーレン中空粒子、１０…窒化ホウ素ナノチューブ材料、２０…ＩＣＰ装置、２１…プラズマトーチ、２２…反応容器、２３…サイクロン、２４…フィルター、２０１…２層窒化ホウ素ナノチューブ、２０２…３層窒化ホウ素ナノチューブ、３０３…アモルファス成分、６０１…窒化ホウ素ナノチューブのバンドル、９０１…ＢＮＮＴ／アルミニウム複合材料中の窒化ホウ素ナノチューブ、１００１…ＢＮＮＴ／フッ素樹脂複合材料中の窒化ホウ素ナノチューブ。 1, 101, 101a, 101b, 501: boron nitride nanotubes, 2,301: boron particles, 3,302: boron nitride fullerene, 4, 102: boron nitride fullerene particles, 4a: boron nitride fullerene particles, 4b: with growing body Boron nitride fullerene particles, 7: boron nitride fullerene hollow particles, 7a: boron nitride fullerene hollow particles, 7b: boron nitride fullerene hollow particles with growth, 401, 502: boron nitride fullerene hollow particles, 10: boron nitride nanotube material, 20 ... ICP device, 21 ... plasma torch, 22 ... reaction vessel, 23 ... cyclone, 24 ... filter, 201 ... double-walled boron nitride nanotube, 202 ... 3-walled boron nitride nanotube, 303 ... amorphous component, 601 ... bundle of boron nitride nanotube , 9 1 ... BNNTs / aluminum composites of boron nitride nanotubes, 1001 ... BNNTs / fluororesin composite boron nitride nanotubes in the material.

Claims (22)

  1. 　窒化ホウ素ナノチューブと、窒化ホウ素フラーレン中空粒子とを含み、
    　前記窒化ホウ素フラーレン中空粒子が前記窒化ホウ素ナノチューブの間に分散されていることを特徴とする窒化ホウ素ナノチューブ材料。     Including boron nitride nanotubes and boron nitride fullerene hollow particles,
    A boron nitride nanotube material, wherein the boron nitride fullerene hollow particles are dispersed between the boron nitride nanotubes.
  2. 　前記窒化ホウ素ナノチューブは、前記窒化ホウ素フラーレン中空粒子と接触しているものを含んでいることを特徴とする請求項１に記載の窒化ホウ素ナノチューブ材料。 The boron nitride nanotube material according to claim 1, wherein the boron nitride nanotubes include those in contact with the boron nitride fullerene hollow particles.
  3. 　前記窒化ホウ素フラーレン中空粒子は、窒化ホウ素フラーレン中空粒子の表面から窒化ホウ素ナノチューブが成長した成長体付き窒化ホウ素フラーレン中空粒子を含んでいることを特徴とする請求項１または２に記載の窒化ホウ素ナノチューブ材料。 The boron nitride fullerene hollow particles according to claim 1 or 2, wherein the boron nitride fullerene hollow particles include boron nitride fullerene hollow particles with a grown body in which boron nitride nanotubes are grown from the surface of the boron nitride fullerene hollow particles. material.
  4. 　前記窒化ホウ素ナノチューブおよび前記窒化ホウ素フラーレン中空粒子が、２層以上５層以下の多層構造を有することを特徴とする請求項１から３のいずれか１項に記載の窒化ホウ素ナノチューブ材料。 The boron nitride nanotube material according to any one of claims 1 to 3, wherein the boron nitride nanotubes and the boron nitride fullerene hollow particles have a multilayer structure of 2 to 5 layers.
  5. 　前記窒化ホウ素フラーレン中空粒子の平均粒子径が、５ｎｍ以上１００ｎｍ以下であることを特徴とする請求項１から４のいずれか１項に記載の窒化ホウ素ナノチューブ材料。 5. The boron nitride nanotube material according to claim 1, wherein the boron nitride fullerene hollow particles have an average particle diameter of 5 nm or more and 100 nm or less. 6.
  6. 　前記窒化ホウ素ナノチューブの平均直径が、１ｎｍ以上５０ｎｍ以下であることを特徴とする請求項１から５のいずれか１項に記載の窒化ホウ素ナノチューブ材料。 6. The boron nitride nanotube material according to claim 1, wherein the boron nitride nanotube has an average diameter of 1 nm or more and 50 nm or less. 7.
  7. 　前記窒化ホウ素ナノチューブは、前記窒化ホウ素フラーレン中空粒子の比表面積の０．１倍以上１０倍以下の比表面積を有することを特徴とする請求項１から６のいずれかに記載の窒化ホウ素ナノチューブ材料。 The boron nitride nanotube material according to any one of claims 1 to 6, wherein the boron nitride nanotube has a specific surface area of 0.1 to 10 times the specific surface area of the boron nitride fullerene hollow particles.
  8. 　母材と、窒化ホウ素ナノチューブと、窒化ホウ素フラーレン中空粒子とを含み、
    　前記窒化ホウ素ナノチューブと前記窒化ホウ素フラーレン中空粒子とが前記母材に分散されていることを特徴とする窒化ホウ素ナノチューブ複合材料。     Including a base material, boron nitride nanotubes, and boron nitride fullerene hollow particles,
    The boron nitride nanotube composite material, wherein the boron nitride nanotubes and the boron nitride fullerene hollow particles are dispersed in the matrix.
  9. 　前記窒化ホウ素ナノチューブは、前記窒化ホウ素フラーレン中空粒子と接触していることを特徴とする請求項８に記載の窒化ホウ素ナノチューブ複合材料。 The boron nitride nanotube composite material according to claim 8, wherein the boron nitride nanotube is in contact with the boron nitride fullerene hollow particles.
  10. 　前記母材が、アルミニウム、チタン、ニッケル、鉄またはこれらの合金であることを特徴とする請求項８または９に記載の窒化ホウ素ナノチューブ複合材料。 10. The boron nitride nanotube composite material according to claim 8, wherein the base material is aluminum, titanium, nickel, iron, or an alloy thereof.
  11. 　前記母材が、熱硬化性樹脂、熱可塑性樹脂またはフッ素含有樹脂であることを特徴とする請求項８または９に記載の窒化ホウ素ナノチューブ複合材料。 10. The boron nitride nanotube composite material according to claim 8, wherein the base material is a thermosetting resin, a thermoplastic resin, or a fluorine-containing resin.
  12. 　（ａ）窒化ホウ素ナノチューブと、ホウ素粒子の表面に窒化ホウ素フラーレンが形成された窒化ホウ素フラーレン粒子とを含み、前記窒化ホウ素フラーレン粒子が前記窒化ホウ素ナノチューブの間に分散されている第１の生成物を得る工程と、
    　（ｂ）前記（ａ）の工程で得られた前記第１の生成物に含まれる前記窒化ホウ素フラーレン粒子からホウ素成分を除去して窒化ホウ素フラーレン中空粒子を生成し、前記窒化ホウ素フラーレン中空粒子が前記窒化ホウ素ナノチューブの間に分散されている第２の生成物を得る工程と、を有することを特徴とする窒化ホウ素ナノチューブ材料の製造方法。     (A) a first product comprising boron nitride nanotubes and boron nitride fullerene particles having boron nitride fullerenes formed on the surfaces of boron particles, wherein the boron nitride fullerene particles are dispersed between the boron nitride nanotubes Obtaining a
    (B) removing a boron component from the boron nitride fullerene particles contained in the first product obtained in the step (a) to produce boron nitride fullerene hollow particles; Obtaining a second product dispersed between the boron nitride nanotubes.
  13. 　前記第１の生成物は、前記窒化ホウ素フラーレン粒子の表面から前記窒化ホウ素ナノチューブが成長した、成長体付き窒化ホウ素フラーレン粒子を含んでおり、
    　前記第２の生成物は、前記成長体付き窒化ホウ素フラーレン粒子からホウ素成分を除去して成長体付き窒化ホウ素フラーレン中空粒子を生成し、前記窒化ホウ素ナノチューブの中に、前記成長体付き窒化ホウ素フラーレン中空粒子を含む構成を有する窒化ホウ素ナノチューブ材料を作製することを特徴とする請求項１２に記載の窒化ホウ素ナノチューブ材料の製造方法。     The first product, the boron nitride nanotubes grown from the surface of the boron nitride fullerene particles, including boron nitride fullerene particles with a growing body,
    The second product removes a boron component from the boron nitride fullerene particles with the growing body to produce boron nitride fullerene hollow particles with the growing body, and the boron nitride fullerene with the growing body is formed in the boron nitride nanotube. The method for producing a boron nitride nanotube material according to claim 12, wherein a boron nitride nanotube material having a configuration including hollow particles is produced.
  14. 　前記（ｂ）の工程が、前記第２の生成物を熱処理して前記ホウ素粒子を酸化ホウ素とする酸化熱処理工程と、
    　前記酸化熱処理工程後の前記第２の生成物から前記酸化ホウ素を除去する酸化物除去工程と、を有することを特徴とする請求項１２または１３に記載の窒化ホウ素ナノチューブ材料の製造方法。     The step (b) is an oxidizing heat treatment step of heat treating the second product to turn the boron particles into boron oxide;
    The method for producing a boron nitride nanotube material according to claim 12, further comprising: an oxide removing step of removing the boron oxide from the second product after the oxidation heat treatment step.
  15. 　前記（ａ）の工程における第１の生成物が気相合成法を用いて得られることを特徴とする請求項１２から１４のいずれか１項に記載の窒化ホウ素ナノチューブ材料の製造方法。 The method for producing a boron nitride nanotube material according to any one of claims 12 to 14, wherein the first product in the step (a) is obtained by a gas phase synthesis method.
  16. 　前記気相合成法は、レーザー気化、熱分解、直流プラズマまたは高周波誘導プラズマから選択されることを特徴とする請求項１５に記載の窒化ホウ素ナノチューブ材料の製造方法。 16. The method according to claim 15, wherein the gas phase synthesis method is selected from laser vaporization, thermal decomposition, direct current plasma, and high frequency induction plasma.
  17. 　前記酸化熱処理工程において、前記熱処理を４５０℃以上１０００℃以下の温度で行うことを特徴とする請求項１４に記載の窒化ホウ素ナノチューブ材料の製造方法。 The method according to claim 14, wherein in the oxidizing heat treatment step, the heat treatment is performed at a temperature of 450 ° C or more and 1000 ° C or less.
  18. 　前記酸化物除去工程において、前記酸化ホウ素を、エタノール、メタノール又は水により洗浄除去することを特徴とする請求項１４に記載の窒化ホウ素ナノチューブ材料の製造方法。 15. The method for producing a boron nitride nanotube material according to claim 14, wherein in the oxide removing step, the boron oxide is washed and removed with ethanol, methanol, or water.
  19. 　前記窒化ホウ素フラーレン粒子、前記窒化ホウ素フラーレン中空粒子及び前記窒化ホウ素ナノチューブを、２層以上５層以下からなる多層構造にすることを特徴とする請求項１２から１８のいずれか１項に記載の窒化ホウ素ナノチューブ材料の製造方法。 The nitride according to any one of claims 12 to 18, wherein the boron nitride fullerene particles, the hollow boron nitride fullerene particles, and the boron nitride nanotube have a multilayer structure including two or more and five or less layers. A method for producing a boron nanotube material.
  20. 　前記窒化ホウ素フラーレン中空粒子の平均粒子径を、５ｎｍ以上１００ｎｍ以下に生成させることを特徴とする請求項１２から１９のいずれか１項に記載の窒化ホウ素ナノチューブ材料の製造方法。 20. The method according to any one of claims 12 to 19, wherein the boron nitride fullerene hollow particles have an average particle diameter of 5 nm or more and 100 nm or less.
  21. 　前記窒化ホウ素ナノチューブを、平均直径１ｎｍ以上５０ｎｍ以下に成長させることを特徴とする請求項１２から２０のいずれか１項に記載の窒化ホウ素ナノチューブ材料の製造方法。 21. The method for producing a boron nitride nanotube material according to claim 12, wherein the boron nitride nanotube is grown to an average diameter of 1 nm or more and 50 nm or less.
  22. 　前記窒化ホウ素ナノチューブを、前記窒化ホウ素フラーレン中空粒子の比表面積の０．１倍以上１０倍以下の比表面積に成長させることを特徴とする請求項１２から２１のいずれか１項に記載の窒化ホウ素ナノチューブ材料の製造方法。 The boron nitride according to any one of claims 12 to 21, wherein the boron nitride nanotubes are grown to a specific surface area of 0.1 to 10 times the specific surface area of the boron nitride fullerene hollow particles. Method for producing nanotube material.
PCT/JP2019/030442 2018-08-09 2019-08-02 Boron nitride nanotube material, boron nitride nanotube composite material, and method for producing boron nitride nanotube material WO2020031883A1 (en)

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