HK1175767A - Carbon material and method for producing same - Google Patents

Description

Carbon material and method for producing same

Technical Field

The present invention relates to a novel structure and a novel production method of an artificial graphite material and a composite material of artificial graphite and artificial silicon (Si) used for electrode materials, diffusion layers, heat-generating materials, crystal growth crucibles such as crystalline silicon and silicon carbide, heat insulating materials, reactor vessels for nuclear power generation, additives for conductive films and semiconductor films, and the like of lithium ion batteries, lithium ion capacitors, fuel cells, solar cells, other primary batteries, secondary batteries, steel making, refining, electrolysis, and the like.

Background

Graphite materials are chemically stable, have excellent electrical conductivity and thermal conductivity, and have excellent mechanical strength at high temperatures, and therefore are widely used for steel-making electrodes, high-purity silica electrodes for arc melting and reduction, aluminum refining electrodes, and the like. Graphite has a crystal structure in which hexagonal carbon networks grown from hexagonal carbon rings generated by SP2 hybrid orbitals of carbon atoms are stacked, and is classified into hexagonal crystals and rhombohedral crystals according to the stacked state, and since the carrier concentration and mobility of free electrons, holes, and the like in the hexagonal carbon networks are high, excellent conductivity between electricity and heat is exhibited.

On the other hand, since the carbon hexagonal network surfaces are weakly bonded to each other by so-called van der waals force, the interlayer is relatively easily subjected to sliding deformation, and therefore, the strength and hardness of graphite are soft as compared with those of a metal material and have self-lubricity.

Natural graphite produced naturally is polycrystalline and therefore breaks at the crystal particle interface, is produced in a sheet form, and is not obtained in a bulk form having sufficient hardness and strength. Therefore, natural graphite is generally classified according to its particle size and used as an aggregate (filler).

On the other hand, in order to utilize the excellent properties of graphite, it is necessary to produce a structure having practical strength and hardness for use in the above-described various applications, and it is difficult to obtain a structure from a natural graphite monomer, and thus various artificial graphite materials have been developed and put into practical use as so-called artificial graphite materials.

(method for producing Artificial graphite Material in general)

An artificial graphite material, which is an artificial graphite material, is produced by mixing a filler, which is an aggregate, with a binder, and then molding, carbonizing, and graphitizing the mixture. It is essential that the carbonization yield of the carbon residue after carbonization and firing together with the filler and the binder is high, and an appropriate artificial graphite material is selected depending on the respective applications.

As the filler, pre-fired petroleum coke, pre-fired pitch coke, natural graphite, pre-fired smokeless carbon, carbon black, or the like is used. These fillers are kneaded with coal tar pitch, coal tar, a polymer resin material, and the like, and molded into a desired shape by a method such as extrusion, casting, pressing, and the like.

The molded material is carbonized by firing at a temperature of 1000 ℃ or higher in an inert atmosphere, and then is fired at a high temperature of 2500 ℃ or higher, thereby graphitizing the graphite crystal structure. In the carbonization and firing, since the constituent elements other than carbon, such as hydrogen and nitrogen, are decomposed and generated as moisture, carbon dioxide, hydrogen and hydrocarbon gas, the firing temperature is controlled at a low speed, and generally, a very long production time of 10 to 20 days of temperature rise, 5 to 10 days of cooling, and 15 to 30 days in total is required.

Further, the graphitization treatment is produced by conducting electric heating in a large-scale furnace such as acheson resistance heating furnace, and in the graphitization treatment, the period of electric heating for 2 to 7 days, cooling for 14 days, and total for 16 to 21 days is required, and if the raw material, molding, carbonization and calcination, and graphitization are added, a series of production periods of about 2 months are required (non-patent document 1).

The general artificial graphite has the following tendency: the filler added in the molding step tends to conform in shape in a certain direction, and crystallinity is improved with carbonization and graphitization, so that anisotropy is increased, and the bulk density and mechanical strength are reduced.

Although they are hydrocarbon-based materials that are carbonized after heat treatment together with the filler and binder used, they are roughly classified into easily graphitizable materials that are easily graphitizable and non-graphitizable materials that are difficult to graphitizate by crosslinking of the benzene rings in the structure, depending on their chemical structures.

(method for producing high-Density Isotropic graphite Material)

As means for increasing the density, there are methods of adjusting the particle size distribution, improving the compatibility with the binder pitch, repeating impregnation treatment, and the like, using a graphitizable filler such as mesocarbon microbeads, hard pitch coke, and carbon beads, which are composed of a mesophase-extracted component. In addition, in order to impart isotropy, it is effective to apply isotropic pressure using a cold isostatic press in the molding stage, and this is a common method. Further, in order to obtain a high-density product, a binder pitch is impregnated again with a material once having completed a graphitization step, and the graphitization treatment is repeated, and the production period in this case is 2 to 3 months, which requires an extremely long period.

When the catalyst is used for electrode materials, nuclear applications, and the like, the purity of the material becomes a problem, and therefore, it is necessary to perform a high-purity treatment using a halogen gas such as chlorine gas at a high temperature of about 2000 ℃. By the high-purity treatment, the impurity concentration of the material is reduced to about several hundred ppm.

In general, artificial graphite and high-density isotropic graphite are produced by liquid or solid raw materials and predominantly undergo a liquid-solid phase reaction or a solid-phase reaction in the steps of molding, carbonization and graphitization. Elements such as hydrogen, oxygen, and nitrogen are gradually diffused from a hydrocarbon-based material, and a benzene ring network is gradually expanded to approach a graphite crystal structure by growth and lamination of a carbon hexagonal network surface, but particularly in a graphitization step, since a reaction is carried out in a solid phase, a high temperature of 2500 ℃ or higher and an extremely long reaction time are required.

The reason for the artificial graphite and the high-density isotropic graphite is that they are in a liquid phase or a solid phaseBecause of the graphitization, it is difficult to completely crystallize (graphitize) even if it is heat-treated at a high temperature of 3000 ℃ or higher for a long time, and the theoretical density of graphite is less than 2.26g/cm³There is also a limit to its crystallite size.

(Heat treatment of Polymer resin Material)

Carbon fibers made of a resin such as Polyacrylonitrile (PAN), coal, or petroleum pitch are drawn into fibers at the stage of polymer material, and then carbonized and graphitized by heat treatment. Further, a highly oriented graphite film having high crystallinity can be produced by depositing or coating boron, a rare earth element, or a compound thereof on a polyimide film or a polyimide carbide film, laminating a plurality of the films, and then subjecting the films to edge firing at a temperature of 2000 ℃ or higher in an inert atmosphere in a direction perpendicular to the film surface of the film, but the thickness is limited to about several millimeters (patent document 1).

(method for producing graphite-based Material by vapor phase growth)

There is a method for producing carbon and graphite materials by Vapor phase growth using a hydrocarbon or hydrogen gas as a raw material and contacting the raw material with a metal catalyst at a high temperature using a reaction vessel such as a cvd (chemical Vapor deposition) apparatus. Examples of carbon materials produced by vapor phase growth include vapor grown carbon fibers, carbon nanotubes, carbon nanohorns, and fullerenes.

In the case of vapor grown carbon fibers, a catalyst-supporting substrate is prepared by suspending an oxide of a transition metal having a size of several hundred angstroms in a solvent such as alcohol, spraying the suspension onto a substrate, and drying the substrate. The substrate is placed in a reaction vessel, and a hydrocarbon gas is flowed at a temperature of about 1000 ℃, whereby carbon fibers grow from the surface of the transition metal on the substrate by a vapor phase reaction. Further, there is also a case where a gas of an organic transition metal compound and a hydrocarbon-based gas are mixed and passed through a reaction vessel at about 1000 ℃ (patent document 2).

Next, the carbon fiber obtained by vapor phase growth is heat-treated at a high temperature of 2000 ℃ or higher in a graphitization treatment furnace to obtain a graphitized fiber (patent document 3). When graphitized fibers are directly produced by vapor phase growth, a reaction temperature of about 2000 ℃ is necessary, but in this temperature range, the transition metal as a catalyst liquefies and gasifies, and the function of the catalyst does not appear, so generally, carbonization at a low temperature is performed, and then graphitization is separately performed.

(carbon nanotubes)

Carbon nanotubes are extremely small substances having an outer diameter of nm order and having a carbon hexagonal mesh surface with a thickness of several atomic layers in a cylindrical shape, and have been found in 1991 (non-patent document 1). It is known that such carbon nanotubes are produced by arc discharge of a cathode deposit formed by arc discharge of a carbon material such as graphite, using a carbon material such as graphite as an anode and a heat-resistant conductive material as a cathode, while adjusting the gap between the anode and the cathode in accordance with the growth of the cathode deposit (patent document 4).

Carbon nanotubes are produced by arc discharge, but a large-scale reaction apparatus is required, and the yield obtained is extremely low, and a large number of synthesis methods have been studied. Generally, in arc discharge of carbon used for producing nanotubes, plasma is generated in a reaction vessel filled with an inert gas in a state containing carbon molecular species such as C, C2 and C3, and these small carbon molecular species are solidified into soot, fullerene, nanotubes, or a high-density solid in the next stage. Therefore, the yield of nanotubes is improved by optimizing the gas partial pressure and the plasma temperature in the chamber (patent document 5).

(method of precipitating highly oriented graphite in glassy carbon)

Japanese patent No. 2633638 (patent document 6) discloses that a thermosetting resin is molded into a thick plate by hot pressing or the like, carbonized to form glassy carbon, and hot isostatic pressed at 2000 ℃ or higher to deposit graphite in the glassy carbon in the form of the center-most filling of a japanese snack. In this method, it is necessary to limit the thickness of the glassy carbon to about 6mm that can be fired, and after the graphite is formed, the shell of the glassy carbon is broken to remove the graphite precipitate.

(composite of Artificial graphite and Artificial silicon (Si))

Si is capable of storing Li about 10 times as much as graphite as a negative electrode material for lithium ion batteries, and because this storage expands in volume about 3 times, it breaks down even when it is in the form of particles, thin films, or wafers. Therefore, it is difficult to put the battery into practical use as a stable negative electrode material for a battery. However, it has been found that resistance to swelling and destruction can be improved by using a one-dimensional material (one-dimensional nano-silicon material, for example, Si nanowires, Si nanorods) in which Si has a submicron size.

(interlayer Compound)

Since the graphene layer can hold both electrons and holes (holes) as carriers, it is possible to form an interlayer Compound (interlayer Compound) of either an electron accepting acceptor type or an electron donating donor type. As such an interlayer compound, various studies and developments have been made on graphite having a large number of stacked layers of graphite, and a graphite interlayer compound is known. (non-patent document 3).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3065896

Patent document 2: japanese examined patent publication No. 62-49363

Patent document 3: japanese patent No. 2664819

Patent document 4: japanese patent No. 2526408

Patent document 5: japanese patent No. 2541434

Patent document 6: japanese patent No. 2633638

Non-patent document

Non-patent document 1: nature, 354: pp 56-58, 1991

Non-patent document 2: nature nanotechnology, 3: page 31, 2008

Non-patent document 3: rice-wall doffer, carbon 1989[ No.139]207-213

Disclosure of Invention

Problems to be solved by the invention

When a graphite material having good crystallinity (degree of graphitization) is produced in the form of a block, a cylinder, a pillar, a sheet, or the like, it is necessary to graphitize a carbonized material at a high temperature of about 3000 ℃ for a long time by a solid phase reaction, and productivity is remarkably low and cost is high. Furthermore, in order to perform graphitization in a solid phase, it is difficult to obtain complete crystallinity of graphite within an industrially possible graphitization treatment period. In order to obtain a high-density graphite material, it is necessary to control the structural state of the carbon hexagonal mesh surface in the carbonization step in order to perform graphitization even by a solid phase reaction, and there are problems that the steps of raw material adjustment, molding, and carbonization are complicated and complicated, productivity is extremely low, and metal impurities remain.

Further, for electrodes of secondary batteries such as lithium ion batteries and hybrid capacitors, electrodes of fuel cells, diffusion plates, and the like, porous graphite plates and sheets having a high open porosity are necessary, but if the porous body is made of an artificial graphite material, the strength of the material cannot be maintained, and therefore, it is necessary to pulverize the material into powder particles and then apply the powder particles as slurry to metal plates or the like.

In the method for producing vapor grown carbon fibers using a hydrocarbon gas as a raw material, although relatively simple processes can be employed, it is necessary to form a vapor phase reaction chamber (reaction vessel) and a separate process is required for the graphitization treatment, which has a problem that the equipment cost is high for mass production. The obtained material is in the form of fibers having a diameter of 1mm or less, and is required to be impregnated with a binder, compounded with a resin, etc., and carbonized and graphitized again in order to maintain sufficient strength as a graphite member having a desired shape. Further, since the metal catalyst is an essential material for fiber formation, it is necessary to remove the added catalyst metal for high purity.

In the case of a nanocarbon material such as a carbon nanotube, fullerene, or carbon nanohorn, the yield is extremely low, and in order to produce a structural member, it is necessary to compound the nanocarbon material with a polymer material as an additive, carbonize or graphitize the nanocarbon material again, or apply slurry and dry the nanocarbon material.

The method for producing highly oriented graphite by high-pressure (vertical pressure in the direction perpendicular to the material) and high-temperature treatment of polyimide resin has problems such as limitation in the thickness that can be produced, large anisotropy, and extremely low strength.

In the method of precipitating highly oriented graphite by hot isostatic pressing inside a thick material of glassy carbon, it is difficult to sinter dense glassy carbon to a thickness of 10mm or more, and the shell of glassy carbon must be broken to extract the precipitated graphite, so that there is a problem that a large-sized product or a porous product cannot be obtained.

In this way, the conventional method for producing a graphite-based material uses a liquid/solid raw material to perform carbonization and graphitization in a solid phase, and therefore has the following problems: 1) in order to develop a carbon hexagonal network (graphite crystal structure), an extremely long production period of about 2 months is required at a maximum arrival temperature of about 3000 ℃; 2) a complete graphite crystal structure is not obtained, 3) if a complete graphite crystal structure is formed, anisotropy becomes strong and strength becomes weak (strong in the plane direction but soft in the thickness direction), and 4) it is difficult to manufacture a porous body having a large open porosity.

Further, the method of using a gas or solid raw material for carbonization and graphitization in a gas phase (including radicals in plasma) or producing a material of a graphite crystal structure main body such as a carbon nanotube, graphene, fullerene, carbon nanofiber, carbon nanohorn or the like has problems that a reaction vessel is required, production efficiency is extremely low, mass production is difficult, and it is difficult to directly produce a product having a large shape such as a block, a column, a pillar, a plate or the like.

Conventional methods for producing one-dimensional-shaped nano Si materials (Si nanowires, Si nanorods, and the like) have problems of low purity of the target product, low productivity, and high cost because they are synthesized on a substrate on which a catalyst such as Au, In, and Sn is supported.

Means for solving the problems

The inventors of the present invention conducted extensive studies and found that: as a first aspect of the present invention, a sheet-like graphite crystal mass (hereinafter also referred to simply as "sheet-like graphite crystal mass of the present invention") in which sheet-like graphite crystals extending from the inside to the outside are aggregated can be produced by sealing a powder or granules (calcined material) of an organic compound calcined so as to contain residual hydrogen in a container made of a heat-resistant material (for example, a container made of graphite) and subjecting the sealed container and the container to hot isostatic pressing (HIP treatment) using a pressurized atmosphere under predetermined conditions.

In addition, it was found that: as a second aspect of the present invention, the HIP treatment is carried out by mixing powdered silicon with a calcined material and treating the mixture at a temperature at which the highest temperature of the HIP treatment is equal to or higher than a temperature (about 1320 ℃) close to the melting point of Si, thereby producing a one-dimensional shape nano-silicon (Si) material (fibrous Si nanowires or Si nanorods) simultaneously with the production of the flaky graphite crystal ingot of the present invention, and the present invention has been completed.

Further, it was found that: as a third aspect of the present invention, there is provided a sheet-like graphite crystal (for example, multilayer graphene having a high crystallinity of about 10nm or less, particularly multilayer graphene having a thickness of about 3.5nm (about 10 layers), and/or a wrinkled or rolled shape of the sheet-like graphite crystal) suitable for the production of a transparent conductive film, which is produced by using an assembly of sheet-like graphite crystals, which is obtained by assembling the sheet-like graphite crystals, as a raw material, pulverizing the assembly, dispersing the resultant in a solvent, applying ultrasonic waves to the dispersion, centrifuging the resultant, collecting an upper clear liquid, and distilling off the solvent from the upper clear liquid, and thus the present invention has been completed.

Namely, the present invention relates to,

(1) a method for producing a crystalline flake graphite block in which flaky graphite crystals extending outward from the inside are aggregated, comprising: preparing powder and granules of an organic compound which is calcined so as to contain residual hydrogen, placing the powder and granules in a sealed container made of a heat-resistant material, and subjecting the powder and the container to hot isostatic pressing treatment using a pressurized gas atmosphere, wherein the maximum reaching temperature in the hot isostatic pressing treatment is 900 ℃ or higher and less than 2000 ℃,

(2) the production method of the above (1), wherein the maximum reached temperature is 1000 ℃ or higher and lower than 2000 ℃,

(3) the production method of the above (1) or (2), wherein the sealed container made of a heat-resistant material is a graphite sealed container,

(4) the production process according to any one of the above (1) to (3), wherein the residual hydrogen is 6500ppm or more,

(5) the production method of any one of (1) to (3) above, wherein the temperature of the calcination is 1000 ℃ or lower,

(6) the production process according to any one of the above (1) to (5), wherein the graphite closed vessel is a screw-type closed vessel having an open-cell ratio of less than 20% and employing a triangular screw,

(7) the process according to any one of the above (1) to (6), wherein the organic compound is selected from the group consisting of starch, cellulose, protein, collagen, alginic acid, dammar resin, copal resin, rosin, gutta percha, natural rubber, cellulose-based resin, cellulose acetate, cellulose nitrate, cellulose acetate butyrate, casein plastic, soybean protein plastic, phenol resin, urea resin, melamine resin, benzoguanamine resin, epoxy resin, diallyl phthalate resin, unsaturated polyester resin, bisphenol A-type epoxy resin, novolak-type epoxy resin, polyfunctional epoxy resin, alicyclic epoxy resin, alkyd resin, polyurethane resin, polyester resin, vinyl chloride resin, polyethylene, polypropylene, polystyrene, polyisoprene, butadiene, nylon, vinylon, acrylonitrile-based fiber, 1 or more than 2 of rayon, polyvinyl acetate, ABS resin, AS resin, acrylic resin, polyacetal, polyimide, polycarbonate, modified polyphenyl ether, polyarylate, polysulfone, polyphenylene sulfide, polyether ether ketone, fluororesin, polyamide imide, silicone resin, petroleum asphalt, coal asphalt, petroleum coke, coal coke, carbon black, activated carbon, waste plastic, waste PET bottle, waste wood, waste plant and biological garbage,

(8) the production process according to any one of the above (1) to (7), wherein the particulate organic compound is a phenol resin having an average particle diameter of less than 100 μm,

(9) the production method of any one of the above (1) to (8), wherein the hot isostatic pressing treatment is performed in a state in which a part or all of the periphery of the powder or granule of the calcined organic compound charged in the graphite closed container is covered with the spacer and the sleeve.

(10) The production method of the above (9), wherein the spacer and the sleeve are composed of 1 or 2 or more kinds selected from the group consisting of glassy carbon, diamond-like carbon, and amorphous carbon,

(11) the production method of any one of the above (1) to (10), characterized in that 1 or 2 or more carbon materials selected from carbon fibers, natural graphite, artificial graphite, glassy carbon, and amorphous carbon are mixed in the powder or granule of the calcined organic compound,

(12) a method for producing a graphite ingot in which flaky graphite crystals are partially cleaved, comprising: preparing a graphite intercalation compound having the flaky graphite crystal mass obtained by the production method of any one of (1) to (11) as a host material, rapidly heating the compound,

(13) a flaky graphite crystal mass comprising an assembly of flaky graphite crystals extending from the inside to the outside,

(14) a graphite crystal ingot obtained by partially cleaving the flaky graphite crystals of the flaky graphite crystal ingot of the above (13),

(15) a method for manufacturing a one-dimensional nano silicon material comprises the following steps: preparing powder particles of an organic compound which is calcined so as to contain residual hydrogen, mixing the powder particles with silicon, placing the mixture in a closed container made of a heat-resistant material, and subjecting the mixture to hot isostatic pressing treatment using a pressurized gas atmosphere together with the closed container, wherein the maximum reaching temperature in the hot isostatic pressing treatment is 1320 ℃ or higher and less than 2000 ℃,

(16) a method for producing a graphite-silicon composite material comprising a crystalline flake graphite ingot in which crystalline flake graphite crystals extending outward from the inside are aggregated and a one-dimensional shape nano-silicon material, the method comprising: preparing powder particles of an organic compound which is calcined so as to contain residual hydrogen, mixing the powder particles with silicon, placing the mixture in a closed container made of a heat-resistant material, and subjecting the mixture to hot isostatic pressing treatment using a pressurized gas atmosphere together with the closed container, wherein the maximum reaching temperature in the hot isostatic pressing treatment is 1320 ℃ or higher and less than 2000 ℃,

(17) the production method of the above (15) or (16), wherein the maximum reaching temperature is 1350 ℃ or higher and 1800 ℃ or lower,

(18) the production method of any one of (15) to (17) above, wherein the powdered silicon is powdered silicon having a particle size of less than 500 μm,

(19) a graphite-silicon composite material comprising a flaky graphite crystal mass in which flaky graphite crystals extending from the inside to the outside are aggregated and a one-dimensional shape nano-silicon material,

(20) a method for producing flaky graphite crystals dispersed in a solvent, and/or a wrinkled or rolled product thereof, comprising: pulverizing flake graphite crystal aggregate, dispersing the product in solvent, applying ultrasonic wave, centrifuging, collecting supernatant,

(21) a method for producing a flaky graphite crystal, and/or a crinkle and/or rolled deformation thereof, which comprises: distilling the solvent from the flaky graphite crystal dispersed in the solvent and/or the rolled body and/or the rolled deformation thereof of (20) above,

(22) the production method of the above (20) or (21), wherein the aggregated flaky graphite crystals formed by aggregation of flaky graphite crystals are flaky graphite crystal masses formed by aggregation of flaky graphite crystals extending from the inside to the outside,

(23) flaky graphite crystals dispersed in a solvent, and/or a wrinkled or rolled form thereof, comprising multilayer graphene having a thickness of 10nm or less,

(24) a flaky graphite crystal and/or a crinkle and/or a coil-like modification thereof, which comprises multilayer graphene having a thickness of 10nm or less,

(25) the production process according to any one of the above (1) to (10), characterized in that silicon, silicon oxide, titanium oxide or zinc oxide is mixed with the powder or granule of the calcined organic compound,

(26) the flaky graphite crystal ingot of the above (13), wherein silicon is uniformly dispersed,

(27) the flaky graphite crystal ingot of the above (13), wherein titanium oxide is uniformly dispersed,

(28) the flaky graphite crystal ingot of the above (13), wherein zinc oxide is uniformly dispersed.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the method for producing a crystalline flake graphite material of the first aspect of the present invention, it is possible to produce an artificial graphite material having excellent crystallinity and graphite particles or a graphite structure which are difficult to produce and are isotropic as a whole while maintaining high crystallinity and which can be used in a fuel cell, a capacitor, or the like. In addition, the production cycle of the artificial graphite material, which conventionally required 2 to 3 months, can be shortened to several hours, and productivity is greatly improved. As a result, the cost can be reduced, and therefore, the use of carbon materials such as fuel cells and capacitors, which account for a large proportion of the cost, has been becoming more cost-effective and has become more widespread.

In the present invention, since graphite is produced by vapor phase growth, graphite blocks having an ideal graphite crystal structure and crystallite size can be designed and produced in a wide range from high density to porous. Further, since a thin material in which the edge portion of the carbon hexagonal mesh surface faces in the plane direction can be manufactured (a thin material is conventionally obtained, the carbon hexagonal mesh surface is aligned in the plane direction), an electrode material having an ideal structure can be provided as an electrode material for a battery using a reaction of producing a graphite intercalation compound, such as a lithium ion battery or a hybrid capacitor. Further, in applications such as a fuel cell diffusion plate where a graphite material having an appropriate open porosity, good fuel gas permeability, high crystallinity of graphite, high electrical conductivity, high purity and high strength is required, a desirable material can be produced and provided.

According to the second aspect of the present invention, a one-dimensional shape nano-silicon material having improved resistance to expansion and destruction as an electrode material and a graphite-silicon composite material containing the one-dimensional shape nano-silicon material and a crystalline block of flake graphite can be produced with high productivity and/or at low cost without a catalyst and without a substrate. And the obtained nano silicon material, the flake graphite crystal block of the graphite-silicon composite material and the one-dimensional nano silicon material are all high-purity materials. Therefore, a high-performance electrode material or the like can be provided.

According to the third aspect of the present invention, it is possible to efficiently produce the crystalline flake graphite and/or the wrinkled or rolled product thereof. Further, these flaky graphite crystals, and/or a wrinkled body and/or a rolled-up deformed body thereof can be used as a transparent conductive film, a thermal conductive film, an additive material thereof, and the like.

Drawings

Fig. 1 is a sectional view showing the structure of a graphite crucible according to an embodiment of the present invention.

Fig. 2 is a sectional view showing the structure of a graphite crucible according to an embodiment of the present invention, and shows a state in which a calcined raw material is charged.

Fig. 3 is a sectional view showing the structure of a graphite crucible according to an embodiment of the present invention, in which a calcined raw material is charged and the crucible is sealed.

Fig. 4 is a sectional view showing the structure of a graphite crucible according to an embodiment of the present invention, and shows a state in which the crucible is sealed with a spacer covering the entire bottom and upper portions of the calcined raw material 3.

Fig. 5 is a sectional view showing the structure of a graphite crucible according to an embodiment of the present invention, and shows a state in which the entire side surface portion of the calcined raw material 3 is covered with a sleeve and the crucible is sealed.

Fig. 6 is a sectional view showing the structure of a graphite crucible according to an embodiment of the present invention, and shows a state in which the bottom portion, the upper portion, and all the side surface portions of the calcined raw material 3 are covered with a sleeve and a spacer, and the crucible is sealed.

Fig. 7 is a conceptual diagram (cross-sectional view) illustrating a mechanism of vapor-phase growth of graphite on the surface of the calcined raw material according to an embodiment of the present invention.

Fig. 8 shows crystal orientations of carbon hexagonal planes in the crystal structure of graphite.

Fig. 9 is a conceptual diagram illustrating a mechanism of growth of the vapor-phase-grown graphite of the present invention from the surface of the calcined material outward (substantially radially) in the a-axis direction of the graphite crystal.

Fig. 10 is a conceptual view (cross-sectional view) showing the generation of graphite by vapor-phase growth around the powdery and granular calcined raw materials having various shapes according to the embodiment of the present invention.

Fig. 11 is a conceptual diagram showing a mechanism of anisotropic growth and growth of a conventional graphite material.

Fig. 12 is a conceptual diagram illustrating a mechanism in which vapor-phase-grown graphite grows isotropically from the surface of the calcined raw material according to the embodiment of the present invention.

Fig. 13 is a conceptual diagram (cross-sectional view) showing a mechanism of vapor-grown graphite generation on the outer surface and inside of the spherical calcined raw material according to an embodiment of the present invention.

Fig. 14 is a conceptual diagram (cross-sectional view) showing a mechanism of vapor-phase growth of graphite particles on the outer surface of a spherical calcined raw material and formation of a massive graphite structure according to an embodiment of the present invention.

FIG. 15 is a substitute photograph for drawings showing an electron micrograph of the surface of a product of sample No.1 of example 1.

Fig. 16 is a substitute photograph for the drawing showing the high-magnification image of fig. 15.

FIG. 17 is a substitute photograph for the drawing showing an electron micrograph of a cross section of a product of sample No.1 of example 1.

FIG. 18 is an alternative photograph showing an electron micrograph of a cross section of a product of sample No. 5 of example 1.

FIG. 19 is an alternative photograph showing an electron micrograph of a cross section of a product of sample No. 6 of example 1.

FIG. 20 shows the measurement result of Raman spectroscopic spectrum of sample No.1 of example 1.

FIG. 21 shows the measurement result of Raman spectroscopy of sample No. 5 of example 1.

FIG. 22 is a substitute photograph for the drawing showing an electron micrograph of the surface of the product of example 2.

Fig. 23 is a substitute photograph for a drawing showing the high-magnification image of fig. 22. The bars in the photograph are 2 μm.

FIG. 24 is a figure-substituted photograph showing an electron micrograph of the surface of the product of example 3. The bars in the photograph are 20 μm.

Fig. 25 is a Scanning Electron Microscope (SEM) photograph of the sample obtained in example 8. A small amount of vapor phase grown feldspar ink was formed on the surface of the spherical calcined raw material, and carbon nanotubes were also observed.

Fig. 26 is an SEM photograph of the sample obtained in example 8. The photograph appeared white to be silicon, maintaining the particle state.

FIG. 27 is an appearance photograph showing the treated state of the pressure-heat treated sample in example 9. And opening the graphite crucible, and shooting the inner surface of the graphite crucible body and the inner surface of the graphite crucible upper cover. As shown in the figure, white portions are felt-like products, and black portions are a composite material of vapor-phase-grown graphite and a fibrous silicon compound.

Fig. 28 is an SEM photograph of the felt-like product that appears white in the previous figures.

Fig. 29 is an enlarged view of the previous drawing.

Fig. 30 is an enlarged view of the previous figure.

FIG. 31 is an SEM photograph of a portion of the nano-sized fibers in which spherical and disk-shaped materials are formed as a moniliform union, which is contained in the white felt-like product shown in FIG. 28.

Fig. 32 is an SEM photograph of the same product as in the previous figures.

FIG. 33 is an SEM photograph of vapor grown graphite produced in example 9 together with a silicon compound. A large amount of silicon generated in a rod shape was observed.

Fig. 34 is an enlarged view of the rod-shaped silicon in the portion shown in the previous drawing.

FIG. 35 is an SEM photograph of the vapor grown graphite and the silicon compound produced in example 9. This indicates how much fibrous silicon compound is produced.

Fig. 36 is an SEM photograph of a portion where a large amount of rod-like silicon was generated in the sample obtained in example 9.

FIG. 37 is an SEM photograph of a part of a fibrous product in which disk-shaped products are united in a moniliform form in a silicon-based product obtained in example 9.

FIG. 38 is an X-ray diffraction pattern of a sample subjected to the pressure-heat treatment in example 9. In the figure, the upper part is a white felt-like product, and the lower part is a black part. Diffraction lines corresponding to the crystal structures of vapor-grown graphite, silicon and silicon carbide were observed.

Fig. 39 is an SEM photograph of rod-shaped silicon.

FIG. 40 is a qualitative analysis result of EDX (energy dispersive X-ray spectrometry) measured for the observation portion of the previous drawing. A strong peak corresponding to silicon was observed. The peak of Ar corresponds to argon occluded in vapor-phase-grown graphite.

Fig. 41 is a characteristic X-ray diagram in EDX measurement for the observation portion of fig. 39. The portion indicated by SEM is an SEM image (secondary electron image), and the photographs indicated by Si, C, and Ar are characteristic X-ray diagrams of the respective elements (the white dots indicate the portions where the elements exist). In the figure indicated by Si, the same form as that of the rod-like product shown by SEM image was observed, and it was found that Si element was present in this portion. In the figure denoted by C, the form corresponding to the rod shape cannot be confirmed, and thus the rod-shaped portion observed by SEM is mainly composed of Si.

FIG. 42 is the EDX measurement result of the portion of the nano-sized fibers in which spherical and disk-shaped materials are formed as a moniliform union, which is contained in the white felt-like product in FIG. 27. The upper photograph of the figure shows the SEM and characteristic X-ray images, and the lower photograph shows the results of qualitative and quantitative analysis of EDX. The same moniliform pattern was confirmed in the SEM and the characteristic X-ray diagrams of Si and O, and the moniliform product was confirmed to be composed of Si and O since the pattern was not observed in the characteristic X-ray diagram of C.

Fig. 43 is an SEM photograph of the surface of the sample produced in example 10 at the prefiring temperature of 900 ℃.

Fig. 44 is an SEM photograph of the surface of the sample produced in example 10 at the prefiring temperature of 600 ℃.

FIG. 45 is a schematic view showing the structure of a graphite crucible and a vitreous carbon spacer used in example 11 and the state of filling a sample.

Fig. 46 is an appearance photograph showing the state of formation of a film-like product formed of vapor-grown graphite (multilayer graphene) formed on the surface of the glassy carbon spacer in example 11.

FIG. 47 is an SEM photograph of an end portion of the film-like product produced in example 11.

Fig. 48 is an enlarged SEM photograph of the portion that appears flat in fig. 47.

Fig. 49 is an enlarged view of fig. 48.

Fig. 50 is an enlarged SEM photograph of the portion of fig. 47 that appears to be raised.

Fig. 51 is an enlarged view of fig. 50.

Fig. 52 is an SEM photograph of the product on the surface portion of the sample in example 12.

Fig. 53 is an enlarged view of fig. 52.

Fig. 54 is an enlarged view of fig. 53.

FIG. 55 is an SEM photograph of a product of example 13.

Fig. 56 is an enlarged view of fig. 55.

FIG. 57 is an SEM photograph of the product of example 14.

Fig. 58 is an enlarged view of fig. 57.

Fig. 59 is an SEM photograph of the graphene laminated Carbon Nanofiber (CNF) produced in example 15. This indicates a state in which a plurality of graphene sheets are stacked and grown in a fibrous form.

Fig. 60 is an SEM photograph of the graphene laminated CNF produced in example 16.

Fig. 61 is an enlarged view of the previous figure.

FIG. 62 is an SEM photograph of the crystalline flake graphite of the present invention produced in example 17.

Fig. 63 is an enlarged view of the previous figure.

Fig. 64 is a Transmission Electron Microscope (TEM) photograph of the flaky graphite crystal produced in example 18, showing shrinkage (in which the multilayer graphene shrinks in a curtain-like manner).

Fig. 65 is a TEM photograph of the flaky graphite crystal produced in example 18, which was shrunk (the multilayer graphene was shrunk in a curtain shape).

Fig. 66 is a TEM photograph depicting a part of the surface of the flaky graphite crystal (multilayer graphene) produced in example 18.

Fig. 67 is an enlarged view of the flake graphite crystal (multilayer graphene) of the previous figure, capturing a lattice image of the end thereof.

FIG. 68 is a block of graphite crystals obtained by partially cleaving flaky graphite crystals of the crystalline block of flaky graphite of the present invention (example 19).

Fig. 69 is an enlarged view of the previous figure.

Fig. 70 is a Scanning Electron Micrograph (SEM) of the surface of the flaky graphite crystal ingot obtained in example 20.

Detailed Description

The first aspect of the present invention is explained.

The sealed container made of a heat-resistant material according to the present invention (for example, a graphite crucible) functions as a reaction container for causing a CVD reaction caused by a gas such as hydrogen, hydrocarbon, carbon monoxide, and water generated from a calcined raw material in the HIP treatment. Since it is necessary to cause a chemical reaction without diffusing a reaction gas generated inside to the outside while maintaining an isotropic high pressure due to a gas pressure, it is necessary to use an appropriate material and a sealing structure. If the material is too dense, the container (e.g., crucible) may be explosively damaged, which may cause a pressure difference between the inside and outside of the container (e.g., crucible). On the other hand, if the material is too porous, the reaction gas generated inside diffuses to the outside of the container (e.g., crucible), and thus the chemical reaction is inefficient.

In addition, in view of the necessity of taking out the product after the HIP treatment to the outside, it is necessary to seal the container (e.g., crucible) as easily as possible from the viewpoint of productivity of insertion of the raw material before the HIP treatment, it is necessary to expose the container to a high temperature of about 1000 ℃ or higher at the time of the HIP treatment, it is necessary to maintain strength capable of withstanding the internal pressure generated by the generation of the reaction gas from the calcined raw material at a high temperature, and the like, and it is necessary to constitute the container (e.g., crucible) with an appropriate material and structure.

As the heat-resistant material constituting the container, in addition to graphite, ceramics such as alumina, magnesia, zirconia, etc., metals such as iron, nickel, zirconium, platinum, etc., and the like can be cited.

For the material of the container (e.g., crucible), a graphite material is suitable. Specifically, the carbon fiber reinforced carbon material can be composed of an artificial graphite material molded by extrusion molding, CIP molding, die molding, vibration molding, indenter molding, or the like, a hard carbon material mainly containing glassy carbon molded by a thermosetting resin, a carbon fiber reinforced carbon material, and a composite material of these. The porosity of the graphite material is important for efficiently causing a chemical reaction in the container (e.g., crucible), and it is preferable to use a container having an open porosity (apparent porosity) of less than about 20%. In the case of a material having an open porosity of about 20% or more, the reaction gas diffuses to the outside of the container (e.g., crucible), and therefore the concentration required for graphite production cannot be maintained. However, in the case where there is not so much difference between the volume of the container (e.g., crucible) and the volume of the chamber in which the HIP process is performed, even if the open porosity of the container (e.g., crucible) is about 20% or more, the amount of the reaction gas diffused to the outside of the container (e.g., crucible) is not so much, and therefore, there is no great influence on the efficiency.

In the container used in the present invention, a screw-type graphite crucible (fig. 1 to 3) can be used as the graphite crucible, for example, in order to efficiently fill the crucible with the calcined raw material and take out the product after the HIP treatment. Screw portions are engraved in an inner wall 2a of an upper portion of the crucible main body 2 and an outer peripheral portion 1a of the crucible cover portion 1 by a predetermined tap tapping process, and the crucible cover portion 1 is rotated after the pre-fired material 3 is filled so that the screw portions are engaged with each other and screwed to be sealed.

In order to improve the degree of sealing of the calcined raw material, the reaction gas generated from the calcined raw material 3 can be controlled from the upper part and the bottom part of the crucible by using the spacers 4 made of a hard carbon material having a low open pore ratio and subjecting the calcined raw material 3 to hot isostatic pressing while covering all (or a part) of the bottom and the upper part thereof. (FIG. 4)

Further, the reaction efficiency can be improved by hot isostatic pressing the calcined raw material 3 in a state where all (or a part) of the side surface portions thereof are covered with the sleeve 5 made of a hard carbon material having a low open porosity (fig. 5), or in a state where all (or a part) of the periphery of the calcined raw material is covered with the spacer 4 and the sleeve 5 at the same time (fig. 6). Examples of the carbon material constituting the spacer and the sleeve include glassy carbon, diamond-like carbon, amorphous carbon, and the like, and 1 or 2 or more of these may be used simultaneously. The open porosity of the carbon material is typically less than about 0.5%. In the spacer and the sleeve, even if the spacer and the sleeve having an open porosity of 0% are used to entirely cover the periphery of the calcined raw material, a gap is formed in a joint between the spacer and the sleeve, and therefore the calcined raw material is not sealed with the spacer and the sleeve.

Examples of the screw thread in the screw-type graphite crucible include a triangular screw thread (a screw thread having a cross section of a thread ridge in a shape of an approximately regular triangle), a square screw thread, a trapezoidal screw thread, and the like, and among them, the triangular screw thread is preferable.

In the process of producing vapor-grown graphite by HIP treatment using the calcined raw material with hydrogen remaining, the crystallinity and true density of the produced graphite can be controlled by the calcining temperature, the amount of hydrogen remaining in the calcined raw material, the shape of the calcined raw material, the HIP treatment temperature, the pressure, the temperature and pressure raising rate, and the like, regardless of the type of the raw material used.

The residual hydrogen content is not limited as long as it is a sufficient hydrogen content generated from gases such as hydrogen, hydrocarbons, carbon monoxide, and water necessary for the CVD reaction in the HIP treatment from the viewpoint of production of the object of the present invention, and is usually about 6500ppm or more, preferably about 10000ppm or more, and more preferably about 20000ppm or more. The calcined material containing residual hydrogen can be obtained by calcining a powder of an organic compound. In this case, the amount of residual hydrogen generally varies depending on the temperature of the calcination. That is, as the burn-in temperature increases, the amount of residual hydrogen decreases.

The calcination temperature is preferably about 1000 ℃ or lower, preferably about 850 ℃ or lower, more preferably about 800 ℃ or lower, and still more preferably about 700 ℃ or lower.

The thus obtained calcined raw material with residual hydrogen is subjected to HIP treatment under appropriate conditions. The HIP treatment temperature is about 900 ℃ or higher, preferably about 1000 ℃ or higher, to obtain vapor-grown graphite, but at an excessively high temperature (for example, about 2000 ℃), the target is damaged by etching due to excited hydrogen (fig. 19). Therefore, in the present invention, the maximum reaching temperature at the time of the HIP treatment must be about 900 deg.C (preferably, about 1000 deg.C) or more and less than about 2000 deg.C. In addition, the maximum temperature of the HIP treatment is in the range of about 1200 to about 1900 ℃, preferably about 1400 to about 1800 ℃, from the viewpoint of efficiently producing the object of the present invention. The maximum reaching temperature in the HIP treatment must be higher than the pre-firing temperature, and is usually 100 ℃ or higher, preferably 400 ℃ or higher.

The value suitable as the maximum reaching pressure in the HIP treatment varies depending on the particle size of the calcined material, and the HIP treatment can be suitably performed generally in the range of about 1MPa to about 300MPa, preferably about 10MPa to about 200MPa, and preferably about 30MPa to about 200 MPa. For example, when the particle size is large, a larger pressure is necessary as the maximum reaching pressure, while when the particle size is small, a smaller pressure is sufficient. The highest reaching pressure is preferably 70MPa or more in the case of a particle size of several μm to several tens μm or more (e.g., synthetic resin, etc.), but HIP treatment can be suitably performed even at about 10MPa in the case of a particle size of about 1 μm or less (e.g., carbon black, etc.).

In the HIP treatment, it is preferable from the viewpoint of production efficiency to exclude the case where the particle size is as small as about 1 μm or less, and in general, before raising the temperature to the vicinity of the pre-firing temperature, first, raising the pressure to a predetermined pressure (pressure advance mode) to prevent the pre-firing raw material from scattering, then raising the temperature to the vicinity of the pre-firing temperature, and then, if necessary, raising the temperature and pressing the pressure to the maximum reaching temperature and the maximum reaching pressure. The predetermined pressure is, for example, about 70 MPa. On the other hand, when the particle size is as small as about 1 μm or less, the HIP treatment can be efficiently performed without particularly requiring the pressure advance mode described above.

The thus-obtained crystalline flake graphite which is an object of the present invention has high crystallinity. Is that its true density is usually about 1.85g/cm³Above, preferably about 2.0g/cm³Above, more preferably about 2.1g/cm³Above, more preferably about 2.2g/cm³The above flaky graphite ingot having excellent crystallinity. In this true density, the term "about" means that an error of about ± 1% is allowable. However, when the particle size of the calcined raw material is large, the rate of formation of flaky graphite crystal aggregates tends to decrease as described later, and therefore, if the true density of the product after the HIP treatment is measured as it is, the value of the true density may be lower than that described above as the whole product. However, the flaky graphite crystal ingot of the present invention can be suitably used as long as the true density of the portion of the flaky graphite crystal ingot produced is within the above range.

The total porosity of the graphite flake crystal ingot is preferably 40% or more, and more preferably 50% or more. Among the flaky graphite crystal masses, any flaky graphite crystal mass satisfying both the above-described "preferable ranges" of true density and total porosity is more preferable than a flaky graphite crystal mass satisfying only either one of the true density and the total porosity. As such a flake graphite crystal mass, for example, a true density of 1.85g/cm³A flaky graphite crystal mass having a total porosity of 40% or more and a true density of 2.0g/cm³And flake graphite crystal masses having a total porosity of 50% or more, but the present invention is not limited to these, and any combination of these is also within the scope of the present invention.

Fig. 7 shows the mechanism of vapor-phase growth of graphite from the calcined raw material. When the raw material particles 6 obtained by calcining an organic compound are subjected to the HIP treatment under predetermined conditions, a gas 6a such as hydrogen, hydrocarbon, carbon monoxide, or carbon dioxide is generated from the inside of the calcined raw material particles 6 heated to a temperature higher than the calcining temperature. The gas 6a reaches the surface of the calcined raw material particles 6 while passing through the pores in the material. In this process, the vapor-phase-grown graphite 7 is generated by physical and chemical excitation by temperature and pressure. The pre-firing raw material shrinks due to the generation of the reaction gas, and vapor-phase-grown graphite is formed outside and inside.

In the HIP treatment, since a gas such as argon or nitrogen is applied with pressure in the same direction, the graphite crystal grows from the surface 6s of the calcined raw material particle 6 in the in-plane direction 7a of the hexagonal graphite mesh 7 (the a-axis direction of the graphite crystal) in a substantially radial shape as shown in fig. 8 and 9. Further, with the graphite hexagonal mesh surface (graphene) 7 formed at the initial stage of the reaction as a starting point, the graphite hexagonal mesh surface 7 grows while the carbon connecting edge 7a is expanded in the direction of 7a, and the graphite hexagonal mesh surface 7 is laminated in the direction of 7 c. In this case, it is considered that since the high-pressure pressurized medium gas exhibits a shielding effect on the surface of graphene and prevents graphene from adhering, bonding, and multilayering, the growth of graphene in the 7c direction is further suppressed and graphene grows radially from the 7a direction, resulting in the formation of the flake graphite crystal ingot of the present invention.

The shape of the calcined material for the HIP treatment may be any of various shapes such as spherical, ellipsoidal, columnar, cylindrical, fibrous, and irregular block shapes (fig. 10). In all cases, the graphite hexagonal mesh surface 7 spreads in the direction of 7a while carbon bonds are spread in a substantially radial shape from the surface 6s of the calcined raw material particle 6, and the graphite hexagonal mesh surface 7 grows while being laminated in the direction of 7c, thereby growing a graphite structure. Therefore, conventionally, only a graphite material in which the hexagonal graphite mesh 7 grows in one direction in the entire particle, for example, a graphite material having a large anisotropy in which the hexagonal graphite mesh 7 is selectively oriented in the direction of the surface 7a of the particle and in the thickness direction 7c of the particle (fig. 11) can be produced, and in the present invention, the growth of the hexagonal graphite mesh 7 is directed in the direction of 7a and extends substantially radially toward the growth of 7a, and as a result, a flaky graphite crystal block (including isotropic graphite particles and a block-like graphite structure) in which flaky graphite crystals extending from the inside to the outside are aggregated can be obtained (fig. 12). The flaky graphite crystal aggregates may be in the form of isotropic graphite particles, or they may be connected to form a block-like graphite structure.

The generation degree of vapor-grown graphite inside and outside the calcined raw material 6 is determined by the selection of the calcination temperature of the calcined raw material, the amount of residual hydrogen, the graphite crucible structure, and the HIP treatment conditions. By selecting appropriate conditions, as shown in fig. 13, vapor-grown graphite 7 can be grown on the outer surface and inside of the calcined raw material 6, and the crystallinity of graphite in the form of a lump can be increased to increase the true density.

The mechanism of the vapor-phase-grown graphite of the present invention will be described in more detail. The calcined raw material is isotropically pressurized by a pressure medium such as argon or nitrogen in the HIP treatment. Therefore, first, in the initial stage of the HIP treatment, a high-pressure, high-density phase is formed around the particles of the calcined raw material. When the HIP treatment temperature is higher than the pre-firing temperature, gas generation from the pre-firing raw material starts, and the diffusion coefficient of the gas into the high-pressure high-density pressure medium decreases, so that a high-concentration reaction gas region (hydrogen, hydrocarbon, carbon monoxide, etc.) is formed around the pre-firing raw material. Since the HIP treatment is an isotropic pressurization, the reaction gas region is formed uniformly on the outer surface of the particle and in a shape similar to the shape of the particle.

In these reaction gas regions, if the HIP treatment temperature is higher, specifically, about 900 ℃ or higher, the reaction gas is excited to cause a so-called thermal CVD reaction, and vapor-phase-grown graphite is precipitated. The reaction mechanism is a reaction mechanism that is characteristic of the present invention, in which a CVD reaction that is generally performed by supplying a reaction gas to the surface of a substrate using a CVD apparatus, a plasma CVD apparatus, or the like is performed in a reaction gas region generated around a pre-fired raw material in a graphite crucible container by a HIP apparatus. Therefore, in the case of the spherical calcined raw material, as shown in fig. 15, vapor-grown graphite is grown substantially radially from the surface of the sphere, and in the case of the amorphous calcined raw material, vapor-grown graphite is grown similarly from the respective surfaces as shown in fig. 24.

The reason why the optimum range is present in the calcination temperature of the raw material is that in order to efficiently produce graphite by the CVD reaction, it is necessary to form an appropriate raw material gas species such as hydrocarbon, hydrogen, and carbon monoxide, and if the calcination temperature exceeds about 1000 ℃, for example, the residual hydrogen is reduced and graphite deposition does not occur efficiently. The reason why the HIP treatment temperature is within an appropriate range is that thermal excitation of the gas generated at a temperature lower than about 900 ℃ is difficult to occur, the CVD reaction is difficult to progress, and it is found that etching of the deposited graphite by hydrogen occurs if the temperature exceeds about 2000 ℃.

Further, since the CVD reaction mainly occurs on the particle surface with respect to the particle size of the calcined raw material used, if the particle size is large, the ratio of the surface area to the volume becomes small, and as a result, the amount of vapor grown graphite occupied in the obtained material decreases. Therefore, the use of a raw material having a small particle size can increase the production ratio of the vapor-phase-grown graphite 7 as a bulk graphite material (fig. 14). Therefore, in the case of using a spherical resin, from the viewpoint of production efficiency, it is preferable to use a spherical resin having a particle size (average) of about 100 μm or less. However, if the surface of the material is used for growing vapor-grown graphite, for example, hard carbon particles such as glassy carbon, the desired material can be easily obtained by selecting particles larger than 100 μm as necessary.

When a raw material (for example, a thermoplastic resin) that has been melted in the process of the calcination is used as the raw material, the raw material after the calcination may be pulverized and classified in advance to obtain a calcined raw material having a desired size when the HIP treatment is performed. For example, since the thermoplastic resin is obtained as a foam (a brittle sponge-like material) after the calcination, the foam is subjected to the HIP treatment, and the crushed material is classified into a calcined material having a desired size.

Conventionally, only products having high anisotropy such as products in which carbon hexagonal networks are laminated in a film form on the surface of a substrate have been produced, but according to the present invention, vapor-phase-grown graphite can be efficiently produced in a three-dimensional space, and as a result, a flake graphite crystal block (including isotropic graphite particles and bulk graphite structures) in which flake graphite crystals extending from the inside to the outside are aggregated can be produced in a very short time.

Generally, an organic compound is heated to increase its molecular weight, and oxygen, nitrogen, and hydrogen atoms in the structure are released and carbonized because they are thermodynamically unstable. Therefore, most of the organic compounds undergo these reactions by heat treatment at about 300 ℃ or higher, and at about 400 ℃ or higher, carbon and appropriately residual hydrogen, oxygen, nitrogen, and the like become the raw materials for calcination.

The organic compound used in the present invention includes the following organic compounds. Specifically, for the natural organic polymer, starch, cellulose, protein, collagen, alginic acid, dammar resin, copal resin, rosin, gutta percha, natural rubber, and the like can be used, for the semi-synthetic polymer, cellulose-based resin, cellulose acetate, cellulose nitrate, cellulose acetate butyrate, casein plastic, soybean protein plastic, and the like can be used, for the synthetic polymer, phenol resin, urea resin, melamine resin, benzoguanamine resin, epoxy resin, diallyl phthalate resin, unsaturated polyester resin, bisphenol a type epoxy resin, novolac type epoxy resin, polyfunctional epoxy resin, alicyclic epoxy resin, alkyd resin, polyurethane resin, and the like as thermosetting resin, and polyester resin (polyethylene terephthalate (PET) resin, polyethylene terephthalate resin, and the like as thermoplastic resin can be used, Polypropylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polybutylene naphthalate resin, and the like), vinyl chloride resin, polyethylene, polypropylene, polystyrene, and the like, and for synthetic rubber, polyisoprene, butadiene rubber, and the like can be used, and for synthetic fiber, nylon, vinylon, acrylic fiber, rayon, and the like can be used, and further, polyvinyl acetate, ABS resin, AS resin, acrylic resin, polyacetal, polyimide, polycarbonate, modified polyphenylene ether (PPE), polyarylate, polysulfone, polyphenylene sulfide, polyether ether ketone, fluorine resin, polyamide imide, silicon resin, and the like can be used.

Further, petroleum-based pitch, coal-based pitch, petroleum coke, coal coke, carbon black, and activated carbon, which are generated when refining fossil fuels such as petroleum and coal, are used as they are, and from the viewpoint of effectively utilizing carbon in wastes for the purpose of forming a resource-recycling society, introduction of a carbonization system has been advanced in various places, and food-based wastes such as waste plastics, waste PET bottles, waste wood, waste plants, and biological wastes, which are mixtures of the above-described various resins, can also be used as raw material organic compounds.

When these hydrocarbon-based raw materials are released as carbon dioxide and carbon monoxide without being burned with oxygen, the raw materials are mainly burned at a predetermined temperature-raising rate and a predetermined calcination temperature in an inert atmosphere such as a nitrogen gas flow. For the pre-firing, an external heating type batch furnace, a high continuous type multi-tube furnace, an internal heating type rotary kiln, a rocking kiln or the like using electricity, gas or the like is used.

A composite material of vapor grown carbon, graphite and various carbon materials, for example, a carbon fiber reinforced carbon material (CC composite material), a graphite carbon composite material, and the like can be produced by mixing various carbon materials such as carbon fiber, natural graphite, artificial graphite, glassy carbon, amorphous carbon, and the like with a pre-fired raw material, filling the mixture into a graphite crucible, and then performing heat treatment using isotropic gas pressure. Therefore, depending on the application of the graphite material, when there are various demands such as a product having higher strength, a product having high porosity, a product having low porosity, and the like, it is possible to cope with the demands by combining various carbon materials.

Graphite has high electrical and thermal conductivity and is frequently used as a current collector and heat collector. Conventionally, these devices have been manufactured by mixing materials that exhibit main functions with graphite, an organic binder, and the like, and heating, drying, pressurizing, and the like. In the present invention, these functional materials are uniformly mixed with the preburning raw material and subjected to HIP treatment to form vapor-grown graphite, whereby a device in which these functional materials are uniformly dispersed and fixed in the vapor-grown graphite can be constituted. Specifically, a composite material in which these functional materials are uniformly dispersed in vapor-phase-grown graphite can be produced by mixing and homogenizing silicon, silicon oxide, titanium oxide, zinc oxide, and the like in a pre-firing raw material, filling the mixture into a graphite crucible, and then performing heat treatment under an isotropic gas pressure.

The graphite flake crystal mass of the present invention is a graphite flake crystal mass in which a graphite intercalation compound (a product in which a sulfate ion, an alkali metal organic complex, or the like is intercalated between graphite layers) containing the graphite flake crystal mass as a main material is prepared and rapidly heated to partially cleave the graphite flake crystal. That is, intercalation of ions or the like between graphite layers causes interlayer expansion of the flaky graphite crystals constituting the flaky graphite crystal mass, thereby generating stress at each part of the flaky graphite crystal mass. Further, by rapidly heating the graphite intercalation compound, the volume of the graphite crystal rapidly expands in the c-axis direction. Through these processes, graphene having a thinner thickness, in which the flaky graphite crystal is effectively cleaved, can be manufactured. The cleaved graphite crystal block is composed of graphene and multi-layer graphene obtained by stacking a plurality of graphene layers, and therefore is useful as an additive for a transparent conductive film or the like having both light transmittance and conductivity.

The graphite intercalation compound can be prepared by a conventional method, for example, by adding the graphite crystal ingot of the present invention obtained as described above to a mixed solution of concentrated sulfuric acid and concentrated nitric acid, a tetrahydrofuran solution of an alkali metal and a condensed polycyclic hydrocarbon, or the like, and stirring. The method for rapidly heating the graphite intercalation compound thus obtained is not particularly limited, and examples thereof include a magnetic crucible made of ceramic, etc. to which the intercalation compound is added, and an electric furnace for heating the crucible, etc. The temperature of the electric furnace in this case is preferably in the range of 600 to 1000 ℃. By doing so, the thickness of the flaky graphite crystal becomes about 0.35 to about 9 nm.

A second aspect of the present invention will be explained.

As the powdery silicon used as the raw material, for example, silicon having a particle diameter of less than 500. mu.m, preferably less than 100. mu.m, more preferably less than 10 μm, still more preferably less than 5 μm, and yet more preferably less than 1 μm can be suitably used. Here, for example, the phrase "silicon having a particle diameter of less than 500 μm" means that 90% or more, preferably 99% or more, and more preferably 99.9% or more of the total particles are less than 500. mu.m, and the phrases "silicon less than 100. mu.m", "silicon less than 10 μm", "silicon less than 5 μm" and "silicon less than 1 μm" are also synonymous. Whether or not these criteria are satisfied can be determined by calculating the proportion of particles satisfying the criteria from the results of actually observing the particle diameter for particles in a predetermined range using an electron microscope such as a Scanning Electron Microscope (SEM).

The mixing of the calcined material and the powdery silicon can be carried out by a conventional method using a ball mill, a powder mixer, or the like. Alternatively, a mixture of the calcined material and the powdered silicon may be obtained by adding relatively coarse silicon chips to the calcined material and mixing the silicon chips while pulverizing the silicon chips in a mortar.

The highest reaching temperature in the HIP treatment is required to be performed at a temperature close to the melting point of silicon and about 1320 ℃. On the other hand, the upper limit of the maximum reached temperature is less than 2000 ℃ as in the first aspect of the present invention. The preferred range of the maximum reach temperature is from about 1350 c to about 1800 c, more preferably from about 1400 c to about 1600 c.

As a preferred range of the highest reaching pressure at the time of the HIP treatment, about 1 to about 300MPa, more preferably about 5 to about 200MPa, can be cited.

The one-dimensional shape nano silicon material related by the invention is fibrous vapor-grown silicon with the diameter of submicron size, more specifically, comprises Si nano filaments with the diameter of about 10 to about 100nm and/or Si nano rods with the diameter of about 100nm to less than about 1 μm, and the like. The length of the material is several micrometers to several mm.

Other conditions and the like are as described above in the first aspect of the present invention. That is, the description of the first aspect can be applied to the second aspect as long as it is not contradictory to the description of the second aspect.

In the third aspect of the present invention, an aggregate of flake graphite crystals, which is obtained by aggregating flake graphite crystals, is used as a raw material, and the aggregate is pulverized, the resultant is dispersed in a solvent, ultrasonic waves are applied thereto, centrifugal separation is performed, a supernatant liquid is collected, and the solvent is distilled off from the supernatant liquid, thereby producing the flake graphite crystals and/or a wrinkled or rolled product thereof.

Since the pressure medium gas adheres to the surface of the sheet-like graphite crystal assembly, the sheet-like graphite crystal assembly or a product obtained by pulverizing the same is subjected to a heat treatment (for example, a temperature of 100 ℃ or higher) as necessary to remove the pressure medium gas, and then the pressure medium gas is supplied to the subsequent step. Further, the flake graphite crystal assembly may be pulverized after being thinned into a thinner layered state before being pulverized. Alternatively, the sheet-like graphite crystal assembly may be pulverized and then made into a thin layer.

The aggregated flake graphite crystal includes all the products in which a plurality of flake graphite crystals are aggregated without being stacked on each other, regardless of the shape and form thereof. Specifically, there may be mentioned (a) a flaky graphite crystal mass (including isotropic graphite particles and a bulk graphite structure formed of the particles, the size of the graphite particles being about 1 to about 1000 μm or about 1 to about 100 μm, the size of the flaky graphite crystals constituting the graphite particles being about 0.1 to 500 μm or about 0.1 to about 50 μm in diameter or width, and the thickness being about 0.35 to about 100nm, preferably about 0.35 to about 10nm, more preferably about 0.35 to about 3.5nm, or about 1 to about 100 nm.) in which flaky graphite crystals extending from the inside to the outside according to the first aspect of the present invention are aggregated; (B) an assembly of flake graphite crystals in a film form, in which each flake graphite crystal grows in the a-axis direction of the graphite crystal substantially perpendicularly to a substrate, and the flake graphite crystal covers the substrate surface and is entirely in the film form (the flake graphite crystal constituting the assembly has a size of about 1 to about 500 μm or about 1 to about 50 μm in diameter or width and a thickness of about 0.35 to about 100nm, preferably about 0.35 to about 10nm, more preferably about 0.35 to about 3.5nm, or about 1 to about 100 nm); (C) an assembly of fibrous flaky graphite crystals in which flaky graphite crystals are grown in the a-axis direction of the graphite crystals from the center of the fibers to the outside, wherein a plurality of flaky graphite crystals are connected to form a fibrous assembly as a whole (the size of the assembly is 1 to 500 μm or 1 to 50 μm in diameter or width, 0.01 to 30mm in length, and the size of the flaky graphite crystals constituting the assembly is 0.1 to 500 μm or 0.1 to 50 μm in diameter or width, and 1 to 100nm in thickness); (D) an aggregate of fibrous flaky graphite crystals, wherein a plurality of flaky graphite crystals are stacked in the c-axis direction of the graphite crystals to constitute a fibrous aggregate as a whole (referred to as graphene stacked Carbon Nanofibers (CNF); the size of the aggregate is about 0.2 to several μm in diameter or width, about 10 to several mm in length, and about several nm in thickness of the flaky graphite crystals constituting the aggregate).

The "flaky graphite crystal" constituting the flaky graphite crystal assembly may also contain a single layer of graphene. Further, as another preferable example of the "flake graphite crystal", there can be mentioned a few-Layer Graphene having the above-mentioned size and the like (Few-Layer Graphene: a multilayer Graphene having a thickness of about 0.35nm to about 3.5nm and about 10 layers at most).

The pulverization can be carried out by physically pulverizing the flake graphite crystal aggregates into fine pieces by using a dry or wet mechanical pulverizer, mixer, blender, ball mill, vibration mill, ultrasonic mill, homogenizer, ultrasonic crusher, mortar, or the like. The wet pulverization can be carried out, for example, by physically pulverizing the flake graphite crystal assembly into fine pieces in a solvent by using a rotary mixer or the like. As the solvent, the same solvent as the solvent in which the product obtained by pulverizing the flake graphite crystal assembly is dispersed can be used, and in this case, ultrasonic waves can be applied immediately after wet pulverization.

Further, the thinning may be performed by exfoliating, cleaving, or the like, the flake graphite crystal assembly or the product obtained by thinning the same as described above. In this case, the cleaving may be performed, for example, in the same manner as the above-described partial cleaving of the flake graphite crystal ingot.

Examples of the solvent usable in the third aspect of the present invention include carbonates such as 1, 2-dichloroethane, benzene, thionyl chloride, acetyl chloride, tetrachloroethylene carbonate, dichloroethylene carbonate, benzoyl fluoride, benzoyl chloride, nitromethane, nitrobenzene, acetic anhydride, phosphorus oxychloride, benzonitrile, selenium oxychloride, acetonitrile, tetramethylsulfone, dioxane, 1, 2-propanediol carbonate, benzyl cyanide, ethylene sulfite, isobutyronitrile, propionitrile, dimethyl carbonate, propylene carbonate, ethylmethyl carbonate, ethylene carbonate, and the like, phenyl phosphite difluoride, methyl acetate, N-butyronitrile, acetone, ethyl acetate, water, phenyl phosphate dichloride, diethyl ether, tetrahydrofuran, diphenyl phosphate chloride, trimethyl phosphate, tributyl phosphate, dimethylformamide, N-methylpyrrolidine, and the like, N-dimethylacetamide, dimethylsulfoxide, N-diethylformamide, N-diethylacetamide, pyridine, hexamethylphosphoramide, hexane, carbon tetrachloride, diglyme, chloroform, 2-propanol, alcohols such as methanol, ethanol, propanol and ethylene glycol, methyl ethyl ketone, 2-methoxyethanol, dimethylacetamide, toluene and polybenzimidazole. These solvents may be used alone or in combination of 2 or more.

In addition, among these solvents, a dispersant may be added in order to increase the amount of dispersion of the flaky graphite crystals or to prevent aggregation of the flaky graphite crystals in the solvent. As the dispersant, in addition to the surfactant, there can be mentioned a dispersant having an electric attraction such as weak binding force and coulomb force to graphene and having a hydrophilic functional group such as a hydroxyl group or a carboxyl group in its structure. Examples of the latter include monomers and polymers of phenols such as phenol and naphthol having a hydroxyl group bonded to the benzene nucleus, monomers and polymers having a carbon double bond such as styrene, propylene, acrylonitrile and vinyl acetate, proteins such as collagen, gelatin, actin, myosin, casein, albumin, GFP and RFP, and amino acids such as glycine, tyrosine, threonine and glutamic acid.

On the other hand, as the surfactant, there can be used anionic surfactants (anionic surfactants) such as fatty acid salts (e.g., sodium laurate), cholate salts (e.g., sodium cholate), monoalkylsulfate salts (e.g., sodium lauryl sulfate), alkylpolyoxyethylene sulfate salts, alkylbenzene sulfonate salts (e.g., sodium dodecylbenzenesulfonate) and monoalkylphosphate salts, alkyltrimethylammonium salts (e.g., cetyltrimethylammonium bromide), cationic surfactants (cationic surfactants) such as dialkyldimethylammonium salts (e.g., didecyldimethylammonium chloride) and alkylbenzyldimethylammonium salts (e.g., alkylbenzyldimethylammonium chloride), amphoteric surfactants (amphoteric surfactants) such as alkyldimethylamine oxides and alkylcarboxylbetaines, polyoxyethylene alkyl ethers (e.g., polyoxyethylene lauryl ether), and the like, Nonionic surfactants (nonionic surfactants) such as fatty acid sorbitan esters, alkyl polyglucosides, fatty acid diethanolamides, and alkyl monoglyceryl ethers, and among them, monoalkyl sulfates, fatty acid salts, and the like can be preferably used.

Among the above solvents, dimethylformamide, water to which a dispersant (preferably a surfactant) is added, 2-methoxyethanol, and the like are preferable.

The amount of the dispersant added is in the range of 0.001 to 10% by weight, preferably 0.02 to 5% by weight, based on the weight of the solvent.

The amount of the flake graphite crystal assembly to be charged is in the range of 0.001 to 50% by weight, preferably 0.01 to 10% by weight, based on the weight of the solvent.

The means for applying the ultrasonic wave is not particularly limited, and for example, the ultrasonic wave can be applied by an ultrasonic washer. The frequency of the applied ultrasonic waves is preferably in the range of about 20 to about 100 kHz. The application time is preferably about 1 to 60 minutes.

The centrifugation is preferably carried out for about 1 to about 60 minutes, preferably about 5 to about 30 minutes, in the acceleration range of about 100 to about 100000G, preferably in the acceleration range of about 100 to about 10000G.

The thus obtained supernatant liquid of the upper layer after centrifugation is dispersed with flaky graphite crystals and/or thin-layered products thereof, and/or their crimped products and/or coil-like deformed products (this dispersion liquid is referred to as "graphene-based dispersion liquid"). To this dispersion, additives (for example, a thickener, a dispersant, a diluent, etc.) generally used in the art can be added as necessary. The graphene-based dispersion can be used as it is as a transparent conductive film, a thermal conductive film, or an additive thereof without distilling off a solvent. Further, by distilling off the solvent from the dispersion liquid by a conventional method, a flake graphite crystal and/or a thin-layered product thereof, and/or a crimped product and/or a coil-like deformed product thereof (hereinafter collectively referred to as "graphene") can be obtained, and these can also be used as an additive material for transparent conductive films and the like.

The graphene thus obtained has a size of several μm to several tens μm in diameter or width and a thickness of about 10nm or less, preferably about 3.5nm or less (the number of stacked layers is about 10 layers), and is a highly crystalline graphene.

In the present invention, the wrinkled or rolled product of the flaky graphite crystal (or a thin-layered product thereof) includes any of a product in which the flaky graphite crystal (or a thin-layered product thereof) is wrinkled, a product deformed into a rolled shape, and a product in which a part of the flaky graphite crystal is wrinkled and a part of the rolled graphite crystal is deformed into a rolled shape. The term "shrinkage" means that the crystal of the flake graphite is shrunk by the shrinkage of the sheet graphite, and may be a product of shrinkage in a single direction or a product of shrinkage in different directions at different positions. The term "deformed into a roll" also means that the product is deformed into a single roll and also includes a product deformed into a plurality of rolls at different positions. The size of the wrinkled or rolled or deformed body of the flaky graphite crystal (or a thin-layered body thereof) is about several tens of micrometers in length and several μm in width. Specific examples of the shrinkage of the flaky graphite crystal include flaky graphite crystals which are shrunk in one direction as shown in fig. 64.

The graphene-based dispersion liquid obtained as described above can be used as an ink for forming a circuit or a thin film in a printable electronic product, for example. That is, by using the dispersion, various printing methods such as flexography (relief printing), offset printing (lithography), gravure printing (intaglio printing), screen printing, inkjet printing, electrophotography, thermal transfer, laser transfer, and the like are used to perform printing on the surface of the substrate, thereby forming a circuit or the like.

In addition, a desired circuit can be formed by applying the dispersion to a substrate by wet coating such as spin coating, slit coating, bar coating, blade coating, or spray coating, and then patterning the substrate by patterning techniques such as nano-contact printing, dip pen etching, nano-transfer, nano-imprinting, EB drawing, or photolithography.

Further, the graphene obtained as described above can be formed into a film on a substrate by dry coating such as vacuum deposition, sputtering, CVD, or the like, and then the substrate is patterned by the patterning technique as described above, whereby a desired circuit can be obtained.

Further, the graphene or the dispersion thereof obtained as described above is dispersed in a raw material resin such as a PET film, an ionomer film (IO film), a polyethylene film made of High Density Polyethylene (HDPE), Medium Density Polyethylene (MDPE), Low Density Polyethylene (LDPE), linear low density polyethylene (L-LPDE), metallocene catalyst linear low density polyethylene (mL-LDPE), or the like, a hard, semi-hard, and soft polyvinyl chloride film (PVC film), a polyvinylidene chloride film (PVDC film), a polyvinyl alcohol film (PVA film), a polypropylene film (PP film), a polyester film, a polycarbonate film (PC film), a polystyrene film (PS film), a polyacrylonitrile film (PAN film), an ethylene-vinyl alcohol copolymer film (EVOH film), an ethylene-methacrylic acid copolymer film (EMAA film), a nylon film (NY film, Polyamide (PA) film), cellophane, a polyimide film, or the like, the mixture can provide various high-functional films such as a transparent conductive film, a highly conductive film, and a highly thermal conductive film containing the graphene, or various high-functional films such as a transparent conductive film, a highly conductive film, and a highly thermal conductive film coated with the graphene by laminating, coating, and drying the graphene or a dispersion thereof on the surfaces of these films.

For producing these, conventional techniques such as melt extrusion molding, inflation, T-die method, flat die method, solution casting, calendering, stretching, multilayer processing, coextrusion by inflation, manifold method, lamination, extrusion lamination, lamination using an adhesive, wet lamination, dry lamination, hot melt lamination, heat sealing, external heating, internal heat generation, corona treatment, plasma treatment, flame treatment, rough surface processing, coating, wet coating, dry coating, vapor deposition, ion plating, and sputtering can be preferably used.

The obtained graphene or its dispersion is added to a thermosetting resin such AS natural resin derived from plants such AS rosin, dammar resin, mastic, copal resin, amber, balsam, natural rubber, shellac, gum, turtle shell, casein, phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane, thermosetting polyimide, etc., a thermoplastic resin such AS polyethylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, polytetrafluoroethylene, ABS resin, AS resin, acrylic resin, etc., a thermoplastic resin such AS polyamide, nylon, polyacetal, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, etc., a polyamide resin, a polyacetal resin, a modified polyphenylene ether, a modified polyphenylene oxide, a polyethylene terephthalate resin, a polyvinyl chloride resin, a polyvinyl acetate resin, a polyvinyl chloride resin, The graphene-containing resin molded article and the resin composite material such as Fiber Reinforced Plastic (FRP) having improved electrical conductivity, thermal conductivity, heat resistance, strength, fracture toughness and flexibility can be obtained by dispersing, mixing, kneading, drying, molding and the like in a plastic raw material such as engineering plastic such as glass fiber reinforced polyethylene terephthalate, cyclic polyolefin, polyphenylene sulfide, polysulfone, polyethersulfone, amorphous polyarylate, liquid crystal polymer, polyether ether ketone, thermoplastic polyimide, polyamideimide and the like.

Further, the obtained graphene or a dispersion thereof is dispersed, mixed, kneaded, dried, molded or the like in a synthetic rubber such as an acrylic rubber, a nitrile rubber, an isoprene rubber, a urethane rubber, an ethylene propylene rubber, an epichlorohydrin rubber, a chloroprene rubber, a silicone rubber, a styrene-butadiene rubber, a fluororubber, a polyisobutylene rubber or the like, whereby a rubber and a rubber composite material containing the graphene, which are improved in electrical conductivity, thermal conductivity, heat resistance, strength, flexibility, can be obtained.

Further, the obtained graphene or its dispersion is dispersed, mixed, kneaded, dried, molded, fired, and sintered with an oxide such as ceramics, glass, cement, mortar, gypsum, enamel, alumina, zirconia, or the like, a hydroxide such as hydroxyapatite, a carbide such as silicon carbide, boron carbide, or the like, a carbonate, silicon nitride, boron nitride, aluminum nitride, a nitride such as GaN, a halide such as fluorite, a phosphate, barium titanate, high-temperature superconducting ceramics, ferrite, lead zirconate titanate, steatite, zinc oxide, or GaAs, to obtain various composite materials containing the graphene, which are improved in electrical conductivity, thermal conductivity, heat resistance, strength, fracture toughness, and electromagnetic wave shielding properties.

Furthermore, the obtained graphene or the dispersion thereof is mixed with tungsten, rhenium, osmium, tantalum, molybdenum, niobium, iridium, ruthenium, hafnium, technetium, boron, rhodium, vanadium, chromium, zirconium, platinum, thorium, lutetium, titanium, palladium, protactinium, thulium, scandium, iron, steel, cast iron, yttrium, erbium, cobalt, holmium, nickel, dysprosium, silicon, terbium, curium, gadolinium, beryllium, manganese, americium, promethium, uranium, copper, samarium, gold, actinium, neodymium, berkelium, silver, germanium, praseodymium, lanthanum, radium, calcium, europium, ytterbium, cerium, strontium, barium, aluminum, magnesium, plutonium, neptunium, antimony, tellurium, zinc, lead, cadmium, thallium, bismuth, polonium, tin, lithium, indium, sulfur, sodium, potassium, rubidium, gallium, cesium, or the like elements thereof, or the alloy thereof, carbide, oxide, nitride, hydroxide or the like, and the mixture is kneaded, rolled, dried, melted, molded, forged, extruded, pelletized, and granulated, and electrically conductive, Various materials containing such graphene, which are improved in thermal conductivity, heat resistance, magnetism, strength, elasticity and fracture toughness.

Among the above-mentioned various materials using graphene, graphene is highly functional because of its most excellent electron mobility and strength among the materials, and a composite material further mixed with fibers such as carbon fibers, graphene, carbon nanofibers, and polyparaphenylene terephthalamide may be produced as necessary.

Further, graphene (particularly, multilayer graphene having a small number of layers) can be formed into an interlayer compound by introducing various guest species, and a single layer of graphene can coordinate a plurality of guest species on the surface thereof (complex compound), as in the case of graphite. As the guest species, semiconductor characteristics (including n-type or p-type) such as a band gap and carrier mobility can be adjusted by selecting an appropriate substance.

As such guest species, alkali metals such as Li, K, Rb, Cs and Na, alkaline earth metals such as Ca, Sr and Ba, metal elements such as Sm, Eu, Yb and Tm, alloys such as K-Hg, Rb-Hg, K-TI and Ba-Na, hydrogen or deuterium compounds such as KH, NaH and KD, compounds such as Li-THF, K-THF, Rb-THF, Cs-THF, Na-THF, K-NH3, Be-NH3, Eu-NH3, Ba-THF and Sr-THF, etc., which coordinate ammonia, various organic molecules and the like to alkali metals and alkaline earth metals, can Be preferably used. Br as a receptor-type substance can also be preferably used₂、F₂、ICl、IF₃Isohalogen, MgCl₂、FeCl₃、FeCl₂、NiCl₂Iso-chlorides, AlBr₃、CdBr₂、HgBr₂、FeBr₃、AsF₅、SbF₅、NbF₅Isohalogen compounds, CrO₃、MoO₃、HNO₃、H₂SO₄、HClO₄And the like. Further, hydrogen fluoride, graphite oxide, and the like can also be preferably used as the receptor-type substance.

The graphite intercalation compound includes a first-order compound in which a guest species intrudes into all interlayers and a second-order compound intruding into every other layer, and the physical properties of the obtained material can be controlled by adjusting the order of the compound, and the same applies to graphene. Examples of the method for adjusting the order include a method using a temperature, a pressure, a concentration, and the like at the time of bringing a solution containing a guest species, a vaporized or liquefied guest species, and a host material into contact.

Among the methods for synthesizing these intercalation compounds and coordination compounds, a 2-zone method or a 2-valve method can be preferably used, in which a graphene as a host material (invaded party) and a guest species (invaded party) are loaded into respective portions of a reaction tube mainly under vacuum and reduced pressure or in an inert gas atmosphere, and a gas phase reaction is caused to occur by applying a temperature difference, a pressure difference, or the like to each of them; a method of simply performing high-temperature treatment on a reaction tube in which the respective materials are mixed; a solution method or an immersion method in which the host material is immersed in various solutions; and a ternary solution method in which a complex or ion of an alkali metal and an alkaline earth metal is formed in a solvent and the host material is brought into contact with the complex or ion.

Further, it is also effective to highly functionalize conventional carbon materials by mixing the obtained graphene or a dispersion thereof with various carbon materials such as artificial graphite, natural graphite, kish graphite, HOPG, activated carbon, carbon black, glassy carbon, diamond-like carbon, and mesophase spherulitic graphite.

The obtained graphene or a dispersion thereof can be applied to electrode materials of various batteries such as lithium ion batteries, lithium ion capacitors, fuel cell electrode substrates, dye-sensitized solar cells, thin-film solar cells, metal air batteries, lithium ion batteries, and nickel hydrogen batteries, hydrogen-absorbing materials, catalytic effects in chemical reactions utilizing the graphene surface, novel reaction fields and drug delivery systems in the pharmaceutical and pharmaceutical fields, and applications thereof are expected.

The above-mentioned aggregated flake graphite crystals (B) and (C) can be produced in the same manner as in the process for producing the flake graphite crystal masses (A) which are the objects of the first aspect of the present invention. For example, in the method for producing a graphite flake crystal block of the above (A), the assembly of flake graphite crystals (B) is produced on the surface of a substrate having a spacer as the substrate. As a material of the substrate, glassy carbon, diamond-like carbon, amorphous carbon, graphite, copper, nickel, iron, cobalt, another heat-resistant metal, ceramic, SiC, GaN, Si, another semiconductor, or the like can be used. The surface of the substrate may be subjected to rough polishing or mirror polishing in advance.

The flake graphite crystal assembly (D) can be produced by preparing a product in which a catalyst is supported on a powder or granule of an organic compound calcined so as to contain residual hydrogen, placing the product in a closed container made of a heat-resistant material, and subjecting the container and the product to hot isostatic pressing treatment using a pressurized gas atmosphere. The catalyst may be a metal such as cobalt, iron, nickel, or zinc, and is preferably supported in a state of being dispersed as uniformly as possible in the calcined raw material. As a method of supporting, in addition to mixing the calcined raw material and the catalyst adjusted to a fine shape, a method may be performed by preparing a product in which a chloride of a metal, a metal complex (acetylacetonato metal), or the like as a catalyst is dissolved in water, alcohol, or a mixed solution thereof, and adding the calcined raw material thereto. The amount of the catalyst used is usually 1000ppm or more, preferably 2000ppm or more, more preferably 10000ppm or more, and still more preferably 100000ppm or more based on the calcined raw material. The other conditions can be carried out in the same manner as the method for producing the crystalline flake graphite block (a) which is the object of the first aspect of the present invention.

In the present invention, the amount of hydrogen is measured by the general method for determining hydrogen of a metal material (JIS Z2614: 1990. analytical method is an inert gas heating method using conditions of "steel". concretely, a sample is heated to 2000 ℃ in an argon atmosphere, and the cumulative amount of hydrogen generated is measured by gas chromatography).

The powder or granule is not specifically limited in size or shape of the particles constituting the powder or granule, and includes a powder formed of relatively fine particles or a granule formed of an aggregate of relatively coarse particles.

The open porosity (apparent porosity) is a ratio of a void (opening) volume which is present in a volume determined from the outer shape of the material and into which a liquid, a gas, or the like can enter. Generally, a material having a high open porosity has continuous pores and gas permeability. In the present specification, the open pore ratio is obtained by the following calculation formula.

Open porosity (%) { (apparent specific gravity-bulk specific gravity)/apparent specific gravity } × 100

Apparent specific gravity: the value of the density of the sample in an uncrushed state was measured by a helium gas replacement pycnometer method using a densitometer AccuPyc1330-PCW manufactured by Shimadzu corporation

Bulk specific gravity: value obtained by dividing the weight of the sample by the volume calculated from the outside dimensions of the sample

The total porosity is a ratio of volumes of all voids (including closed pores as well as open pores) present in a volume determined from the outer shape of the material. In the present specification, the total porosity is determined by the following calculation formula.

Total porosity (%) { (true specific gravity-bulk specific gravity)/true specific gravity } × 100

The true specific gravity is a specific gravity measured in a state in which the material is pulverized into fine powder in order to minimize the influence of voids contained in the material to be measured, and in the examples of the present invention, the measurement is performed using a powder sample passed through a 74 μm sieve.

The apparent specific gravity, bulk specific gravity, and true specific gravity are synonymous with the apparent density, bulk density, and true density, respectively.

In the present specification, the spacer and the sleeve are used by being put into a graphite closed container and inserted between the graphite closed container and the graphite closed container so that the inner wall of the container does not come into direct contact with the calcined raw material. The spacer means a device mainly covering the burn-in material from the top and bottom, and the sleeve means a device mainly covering the burn-in material from the side, and the two devices may not be distinguished from each other depending on the shape of the container.

The term "block" in "block", "block state" or "block structure" means an object in which basic structural units are connected.

The average particle diameter (particle size (average)) was measured by a laser diffraction scattering method using a laser diffraction particle size distribution measuring apparatus. That is, the particle group is irradiated with laser light, and the particle size distribution is calculated from the intensity distribution pattern of diffracted and scattered light emitted therefrom.

In the present specification, for example, when a numerical range is 1200 to 1900, the numerical range means 1200 to 1900.

Examples

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1

Phenol-formaldehyde resin powder having an average particle diameter of 20 μm was calcined at respective maximum reaching temperatures of 600, 700, 900 and 1000 ℃ in an inert gas atmosphere. The residual hydrogen content of the calcined raw material was analyzed according to the general method for determining hydrogen content in metal materials (JIS Z2614: 1990), and the results are shown in Table 1. The calcined raw material calcined at each temperature was charged into a screw-type (triangular screw) graphite crucible made of a material having a bulk density of 1.80 and an open pore rate of 10%, and the screw was tightened while rotating a screw-type upper lid to seal the calcined raw material. The graphite crucible was loaded in a hot isostatic pressing apparatus, heated and pressurized at a temperature and pressure of 600 ℃ and 70MPa for 1 hour using argon gas, heated and pressurized at a temperature-raising rate of 500 ℃ per hour, raised in temperature and pressure at respective maximum reaching temperatures of 190MPa, 1400 ℃, 1800 ℃, 2000 ℃ and 2500 ℃, held at the maximum reaching temperature and pressure for 1 hour, cooled to room temperature, and depressurized. The time required from the insertion of the graphite crucible to the removal of the graphite crucible is 8 to 12 hours. The bulk density, porosity and true density of the treated samples were measured and shown in table 1. The density measurement was performed by using a densitometer AccuPyc1330-PCW manufactured by shimadzu corporation using a helium gas replacement pycnometer method, and the true density was measured in a state where the sample was pulverized into fine powder (the same applies to the density measurement below) (table 1).

TABLE 1

As shown in Table 1, when the calcination temperature was 600 ℃ and the residual hydrogen amount obtained by the above measurement method was 20000ppm, the true density closest to the theoretical density of graphite was obtained (sample No.1, 2), the value of the true density decreased with an increase in the calcination temperature (sample No. 3, 4), and when the calcination temperature was 900 ℃ and the residual hydrogen amount obtained by the above measurement method was 5000ppm, the true density became 1.88 (sample No. 4). The values of the true density were less than 2.0 at the maximum reaching temperature of 2000 ℃ or 2500 ℃ in the hot isostatic pressing treatment at the pre-firing temperature of 900 ℃ or 1000 ℃. Fig. 15 shows the surface of the sample No.1, fig. 16 shows an electron micrograph showing the surface of fig. 15 enlarged, and fig. 17 shows an electron micrograph showing the cross section of the sample No.1, in which the hexagonal graphite mesh surface grows radially on the surface of the spherical calcined raw material.

Fig. 18 shows an electron micrograph of a cross section of a sample No. 5, and fig. 19 shows a cross section of a sample No. 6, in which the degree of growth of the carbon hexagonal mesh surface is low as compared with sample No.1, and particularly in the case of sample No. 6, traces of graphite etching by hydrogen excited at a high temperature of 2000 ℃.

Fig. 20 shows the measurement result of the raman spectroscopic spectrum of sample No. 1. 1580cm was observed^-1Nearby SP²The graphite bond produced peaks, and almost no 1360cm showing a turbostratic structure was found^-1The intensity ratio of the nearby peaks was I1360/I1580 (I)_D/I_G) The R value represented shows a value close to 0, and is a structure extremely excellent in graphite crystallinity. On the other hand, FIG. 21 shows the results of Raman spectrum measurement of sample No. 5, and 1360cm was observed^-1Intensity ratio of nearby peaks I1360/I1580 (I)_D/I_G) A large value is displayed.

Example 2

Phenol formaldehyde resin powder having an average particle diameter of 500 μm was preburnt at a maximum reaching temperature of 600 ℃ in an inert gas atmosphere. The calcined raw materials were treated in the same manner as in example 1, except that the maximum reaching temperature in the hot isostatic pressing treatment was 1400 ℃. The time required from insertion into the graphite crucible to removal therefrom was 12 hours. An electron micrograph of the treated sample is shown in fig. 22, and an enlarged photograph of the surface thereof is shown in fig. 23. Vapor-phase-grown graphite grown radially was observed on the entire surface of the spherical particles, but a bulk structure with bonded particles was not obtained. The true density of the obtained sample was 1.80.

Example 3

The waste material of the PET bottle for beverages was finely cut to about 200 μm (the longest dimension in the vertical and horizontal directions) on average, and was calcined at a maximum reaching temperature of 600 ℃. The calcined raw material was pulverized into particles in a stainless steel mortar, and then treated in the same manner as in example 2. The time required from insertion into the graphite crucible to removal therefrom was 12 hours. Fig. 24 shows an electron micrograph of the treated sample. Vapor-phase-grown graphite grown substantially in radial form was found on the entire surface of the amorphous particles. The true density of the obtained sample was 1.90.

Example 4

Phenol formaldehyde resin powder having an average particle diameter of 20 μm was preliminarily fired at a maximum reaching temperature of 700 ℃ in an inert gas atmosphere. The calcined raw materials were charged into each of the graphite crucibles shown in table 2, and the screw-type upper lid was tightened to seal the calcined raw materials. This graphite crucible was treated in the same manner as in example 2, except that the maximum reaching temperature in the hot isostatic pressing treatment was 1500 ℃.

[ Table 2]

TABLE 2

The material of the graphite crucible is higher in porosity and lower in bulk density, and the true density of the treated sample is lowered (sample No. 8 to 10). When the screw pitch of the graphite crucible was 2mm (sample No. 13), and when the number of the graphite crucible was small (sample Nos. 11 and 12), the true density was lower than that of sample No. 8. Further, compared with the case where the screw shape of the graphite crucible was a triangular screw (sample No. 8), a low true density was obtained for the square screw (sample No. 14) and the trapezoidal screw (sample No. 15).

When the calcined material was inserted into a graphite crucible and sealed, a spacer was made of glassy carbon having low gas permeability and an open pore rate of 0%, and the calcined material was placed so as to cover the entire upper and lower portions thereof (fig. 4, sample No. 16), the true density was increased to 2.19, and a true density of 2.23 was obtained for sample No. 17 (fig. 6) used in combination with a sleeve so as to cover the entire side surface portion of the calcined material.

Example 5

Sample Nos. 2, 5, 6, 16 and 17 were pulverized in an agate mortar, and then the resultant mixture was poured into a mortarPolyvinylidene fluoride and carbon black are mixed together with a small amount of N-methyl-2-pyrrolidone in a weight ratio of 8: 1 to prepare slurry. Next, the slurry was uniformly coated on a nickel screen of 200 mesh size and 0.05mm thickness using a guide groove made of stainless steel and having a hole of 10mm diameter, dried under vacuum at 120 ℃ for 12 hours, and the solvent was distilled off. The dried sample was held between stainless steel plates and hot-pressed at 120 ℃ and 20MPa to prepare a 10 mm-diameter sample electrode. A sample was used as a working electrode, lithium metal was used as a counter electrode, and LiBF was placed in a glove box using an argon atmosphere₄The electrolyte is used for an electrolyte to form a bipolar battery, and the charge-discharge characteristics are measured in a potential range of 0-3V and a current density of 40 mA/g.

Table 3 shows the reversible capacity and coulombic efficiency at cycle 5 as the evaluation results of the initial charge-discharge characteristics of each sample. As the true density of the material increased, the reversible capacity and the coulombic efficiency also increased, and the reversible capacity was 312mAh/g and the coulombic efficiency was 90.8% for sample No. 17.

[ Table 3]

TABLE 3

Example 6

Sample No. 2 was sliced by a diamond-fixed multi-wire saw into a thickness of 10mm in diameter and 90 μm in thickness. The sliced sample dried at 120 ℃ for 1 hour was used as a working electrode, and LiBF was placed in a glove box in an argon atmosphere using metallic lithium as a counter electrode₄The electrolyte is used for an electrolyte to form a bipolar battery, and the charge-discharge characteristics are measured in a potential range of 0-3V and a current density of 40 mA/g. The reversible capacity of charge and discharge cycle 5 was 225mAh/g, and the coulombic efficiency was 95.3%. Since the graphite material is composed of the bulk vapor-phase-grown graphite containing no binder, it is more apparent than the case where the same sample is slurried with a binder as a powderShowing high coulomb efficiency.

Example 7

Silicon chips generated when an ingot of silicon for a solar cell is cut by a diamond saw are recovered in a slurry state together with a coolant. The recovered slurry was dried in the atmosphere, followed by drying in a desiccator at 120 ℃ for 12 hours. In a mortar made of stainless steel, 20 parts by weight of dried silicon chips were put into 80 parts by weight of a phenolic resin powder having an average particle size of 20 μm and calcined at 600 ℃ and thoroughly mixed while pulverizing. The raw material was charged into a screw-type graphite crucible made of a material having a bulk density of 1.80 and an open porosity of 10%, and the raw material was sealed by screwing the screw while rotating a screw-type upper lid. The graphite crucible after sealing was filled in a hot isostatic pressing apparatus, and then heated to 600 ℃ and 130MPa for 3 hours using argon gas, and then heated at a temperature-raising rate of 500 ℃ per hour, pressurized, raised in temperature and pressure at a maximum reaching pressure of 190MPa and a maximum reaching temperature of 1300 ℃, held at the maximum reaching temperature and pressure for 1 hour, cooled to room temperature, and depressurized. The treated sample was in a bulk state, and a composite material in which silicon fine particles were dispersed in vapor grown graphite was obtained.

Example 8

The HIP treatment was carried out in the same manner as in example 7 except that the HIP treatment was carried out under conditions such that the temperature and pressure reached 600 ℃ over 3 hours and 130MPa over 2 hours and the maximum reaching temperature was 1200 ℃.

The treated calcined raw materials were not connected, and vapor-phase-grown graphite composed of multilayer graphene was grown on the surface thereof while maintaining the shape of the primary particles (fig. 25). In addition, carbon nanotubes having a diameter of about 100nm were also produced in a small amount. The silicon mixed in the calcined material exists in a particulate form, and a fibrous silicon-based product is not produced. (FIG. 26)

< graphite-silicon composite >

Example 9

The HIP treatment was carried out in the same manner as in example 8 except that the pressure reached for the first 3 hours was changed from 130MPa to 70MPa, the maximum reaching temperature was 1450 ℃, and the maximum reaching pressure was changed from 190MPa to 90 MPa.

On the upper part of the graphite crucible after the treatment (the surface part of the charged raw material and the space of the crucible upper cover), a large amount of nano-scale fibrous materials composed of silicon, silicon carbide and silicon oxide (silicon-based compound) which are white in visual appearance and felt-like were produced. The appearance photographs of these products adhering to the surfaces of the graphite crucible main body and the upper lid are shown in FIG. 27, and the SEM photographs are shown in FIGS. 28 to 30, and it is confirmed that the products are substantially fibrous with a diameter of about 10 to 100nm and a length of several μm to several mm.

In addition, as shown in fig. 31 and 32, in the sample, a large number of spherical and disk-shaped products were produced as a moniliform combination in a fibril-like product.

In addition, fibrous and rod-like silicon and silicon-based compounds were also produced in the produced vapor-phase-grown graphite, and composites of the vapor-phase-grown graphite and these fibrous and rod-like silicon and silicon-based compounds were obtained. SEM photographs of rod-like silicon produced in vapor-phase-grown graphite are shown in fig. 33 and 34. Fig. 35 shows SEM photographs of fibrous silicon, silicon carbide, and silicon oxide produced in vapor-phase-grown graphite. Fig. 36 shows an SEM photograph of a portion where a large amount of rod-like silicon is produced, and fig. 37 shows an SEM photograph of a portion where disk-like products are united in a fibrous product as a moniliform in a silicon-based product. The products in these samples are summarized in Table 4.

Fig. 38 shows X-ray diffraction patterns of a portion generated in a felt shape and a portion generated in vapor-phase-grown graphite (the upper portion in the figure is a portion generated in a felt shape, and the lower portion is a result of a portion generated in vapor-phase-grown graphite). In the X-ray diffraction pattern of fig. 38, diffraction lines of graphite, silicon (Si), and silicon carbide (SiC) were observed, and it was confirmed that these fibrous products were composed of Si and SiC. Since silicon oxide is amorphous, an X-ray diffraction pattern is not clearly obtained.

Fig. 39 shows an SEM of vapor-grown graphite and rod-like silicon, fig. 40 shows the measurement results of EDX (energy dispersive X-ray spectroscopy) for the portion measured in fig. 39, and fig. 41 shows a characteristic X-ray diagram indicating the presence of each element. From these results, in the case of the rod-shaped silicon, as shown in the characteristic X-ray diagram, the diagram of C is not shown in the rod-shaped portion, and therefore, it can be confirmed that Si alone is a product. In the characteristic X-ray data, the peak indicated as Ar was generated due to the presence of argon gas occluded in the vapor-phase-grown graphite.

Fig. 42 shows characteristic X-ray patterns and graphs of the product produced in the form of a moniliform (fig. 31 and 32), and in this case, peaks and graphs indicating the presence of Si and O were observed, and the presence of silicon oxide (SiO, SiO2) was confirmed. However, in the characteristic X-ray, only the upper part of the surface portion was observed, and therefore, it is considered that fibrous Si or moniliform Si exists in the further inner portion.

[ Table 4]

TABLE 4

Silicon-based product produced in example 9

Example 10

Silicon chips generated when an ingot of silicon for a solar cell is cut by a diamond saw are recovered in a slurry state together with a coolant. The recovered slurry was dried in the atmosphere, followed by drying in a desiccator at 120 ℃ for 12 hours. In a stainless steel mortar, 20 parts by weight of dried silicon chips were put into 80 parts by weight of a phenolic resin powder having an average particle size of 20 μm which had been calcined at 900 ℃ and 600 ℃ and 500 ℃ and thoroughly mixed while being pulverized. The raw material was charged into a screw-type graphite crucible made of a material having a bulk density of 1.80 and an open porosity of 10%, and the raw material was sealed by screwing the screw while rotating a screw-type upper lid. The graphite crucible after sealing is filled in a hot isostatic pressing device, argon gas is used, the temperature and the pressure of 500 ℃ and 70MPa are reached within 3 hours, then heating is carried out at the heating rate of 500 ℃ per hour, pressurization is carried out, the temperature and the pressure are raised at the highest reaching pressure of 90MPa and the highest reaching temperature of 1400 ℃, the temperature and the pressure are kept for 1 hour at the highest reaching temperature and the pressure, and the temperature is reduced to room temperature and the pressure is reduced.

Filament-like silicon was produced by using 3 kinds of samples having different calcination temperatures. When the pre-firing temperature was 500 ℃ and 600 ℃, a large amount of silicon was generated on the surface and inside of the sample, and felt-like silicon was observed on the surface significantly (fig. 44), and when the pre-firing temperature was 900 ℃, no felt-like silicon was generated on the surface of the sample, and a small amount of silicon was generated inside (fig. 43).

< film-like flaky graphite Crystal Assembly (B) >

Example 11

Phenol formaldehyde resin powder having an average particle diameter of 20 μm was preliminarily fired at a maximum reaching temperature of 500 ℃ in an inert gas atmosphere. The residual hydrogen content of the calcined raw material was analyzed according to the general rule for quantitative determination of hydrogen for metal materials (JIS Z2614: 1990), and as a result, 40000ppm of residual hydrogen was contained. The calcined raw material was sealed in a screw-type graphite crucible made of a material having a bulk density of 1.80 and an open pore ratio of 10% while being sandwiched between spacers made of glassy carbon. As shown in fig. 45, the upper spacer is pressed against the guide portion of the graphite crucible by the screw tightening force of the screw by screwing the screw of the upper lid of the graphite crucible, thereby improving the sealing performance. The graphite crucible was loaded in a hot isostatic pressing apparatus, and then heated and pressurized at a temperature-raising rate of 500 ℃ per hour at a temperature-raising pressure of 190MPa and a maximum-reaching temperature of 1800 ℃ for 1 hour using argon gas for 1 hour, and then held at the maximum-reaching temperature and pressure for 1 hour, cooled to room temperature, and depressurized. The spacers made of glassy carbon were mirror-polished.

The treated sample was taken out, and as a result, as shown in fig. 46, a film-like product having a silver color and a metallic luster was deposited on the surface of the spacer made of glassy carbon. The film-like product can be easily peeled off from the spacer, and has a strength enough to stand as a thin film. As a result of observing the surface of the obtained film-like product with an electron microscope, the appearance of a product aggregate in which each flake graphite crystal grows in a direction substantially perpendicular to the surface of the separator was observed as one form of an aggregate of flake graphite crystals in which flake graphite crystals extending from the inside to the outside were aggregated. Further, the product of the growth of multilayer graphene like petals is also included therein. (FIGS. 47 to 51)

< fibrous flaky graphite Crystal Assembly (C) >

Example 12

Phenol formaldehyde resin powder having an average particle diameter of 20 μm was fired at a maximum reaching temperature of 600 ℃ in an inert gas atmosphere. The preburning raw material was filled in a screw-type graphite crucible made of a material having a bulk density of 1.80 and an open pore rate of 10%, and the screw was tightened while rotating a screw-type upper lid, thereby sealing the preburning raw material. The graphite crucible after sealing is filled in a hot isostatic pressing device, argon gas is used, the temperature and the pressure of 700 ℃ and 70MPa are reached within 1 hour, then the heating and the pressurization are carried out at the heating rate of 300 ℃ per hour, the temperature and the pressure are increased at the maximum reaching pressure of 190MPa and the maximum reaching temperature of 1400 ℃, the temperature and the pressure are kept for 1 hour at the maximum reaching temperature and the pressure, the temperature is reduced to the room temperature, and the pressure is reduced. The apparent density of the treated sample was 1.60 and the true density was 2.09. The density measurement was performed by a helium gas replacement pycnometer method using a densitometer AccuPyc1330-PCW manufactured by shimadzu corporation, in a state where the sample was pulverized into fine powder.

In the treated sample, fibrous vapor grown carbon fibers having a diameter of several μm and a length of several μm to several mm were formed (FIGS. 52 to 54). The fibers are in the form of an assembly of flaky graphite crystals formed by assembling flaky graphite crystals extending from the inside to the outside, and the flaky graphite crystals have a special shape in which the graphite crystals are grown from the center of the fibers to the outside. The fibrous product is also present inside the material, but grows to a rather long product at the surface part.

Example 13

The treatment was carried out in the same manner as in the immediately preceding example except that the HIP treatment was carried out under conditions such that the temperature rise rate after 700 ℃ was 700 ℃ per hour and the maximum reaching temperature was 1450 ℃. The apparent density of the treated sample was 1.66 and the true density was 2.05. The density was measured by a helium gas replacement pycnometer method using a densitometer AccuPyc1330-PCW manufactured by shimadzu corporation, in a state where the sample was pulverized into fine powder.

In the same manner, the same form of product as that of the immediately preceding example was produced in the treated sample (FIGS. 55 to 56).

Example 14

The same treatment as in the immediately preceding example was carried out except that the maximum temperature of the pre-firing was set to 500 ℃ and the temperature increase rate after 700 ℃ was set to 500 ℃ per hour under the HIP treatment conditions, and the maximum temperature was set to 1800 ℃. The apparent density of the treated sample was 1.77 and the true density was 2.07. The density was measured by a helium gas replacement pycnometer method using a densitometer AccuPyc1330-PCW manufactured by shimadzu corporation, in a state where the sample was pulverized into fine powder.

In the same manner, the same form of product as that of the immediately preceding example was produced in the treated sample (fig. 57 to 58).

< graphene laminated CNF >

Example 15

The spherical phenolic resin was pre-fired at a maximum arrival temperature of 600 ℃ in a nitrogen stream. The residual hydrogen content in the calcined raw material was measured according to the general method for determining hydrogen in metal materials (JIS Z2614: 1990) and found to be 24000 ppm. 10L of methoxyethanol (purity 99% manufactured by NACALAITESQUE) was mixed with 1mol of cobalt acetylacetonate (manufactured by NACALALA TESSQUE, rating: extra grade, hereinafter referred to as Co (AcAc) 2). At this time, since co (acac)2 was immediately solidified, it was sufficiently pulverized and stirred by using a glass rod or a stirrer. Then, 100ml of distilled water was added dropwise slowly and quantitatively at a time using a syringe or a micropipette. After the precipitate precipitated while being dropped was allowed to stand for a whole day and night, the solution mixed with the precipitate was suction-filtered using an aspirator with a diaphragm pump. Thereby recovering only the precipitate. The resulting precipitate was air-dried in a ventilation box for 24 hours. Assuming that all of the initially used cobalt in the precipitates (cobalt precipitates) is precipitated, the cobalt precipitates and the calcined raw material are dry-mixed so that the cobalt concentration in the raw material to be subjected to the HIP treatment is 5000 ppm. The mixture was charged into a screw-type graphite crucible, and the crucible was sealed by screwing a screw of the upper lid portion. A graphite crucible with a sealed raw material was charged into a HIP apparatus, and the temperature was raised to 1450 ℃ at a temperature raising rate of 500 ℃ per hour while applying hydrostatic pressure of 190MPa with argon gas.

A large amount of fibrous carbon was generated on the surface of the treated sample. The product contained a graphene-laminated CNF having a diameter of about 200 to about 1000nm and a length of about 10 μm to about several mm (FIG. 59). A large amount of long fibers were formed on the surface of the sample, and short fibers were formed around the spherical phenolic resin.

Example 16

The spherical phenolic resin was pre-fired at a maximum arrival temperature of 600 ℃ in a nitrogen stream. Cobalt chloride 6 hydrate was dissolved in ethanol to prepare a 0.6mol/L solution. Then, 120g of the calcined phenol resin was put into 500ml of the solution, and the solution was sufficiently stirred by a stirrer. The residue after the ethanol filtration was put into a ceramic container, and heated at 400 ℃ for 5 hours in the atmosphere with an electric furnace, thereby producing a catalyst-loaded pre-fired raw material. The cobalt concentration was measured by fluorescent X-ray analysis (SEM-EDX) and found to be 3000 ppm. The catalyst-supported pre-sintered raw material was filled in a screw-type graphite crucible, and the crucible was sealed by tightening the screw of the upper lid. A graphite crucible with a sealed raw material was charged into a HIP apparatus, and the temperature was raised to 1400 ℃ at a temperature raising rate of 300 ℃ per hour while applying a hydrostatic pressure of 190MPa with argon gas.

In the treated sample, a large amount of CNFs of a graphene laminated type having a diameter of about 0.5 to about several micrometers were produced. (fig. 60) the thickness of 1 sheet of the CNF of the graphene lamination type was about several nm. (FIG. 61)

< crystalline flake graphite of the present invention >

Example 17

Phenol formaldehyde resin powder having an average particle diameter of 20 μm was preliminarily fired at a maximum reaching temperature of 600 ℃ in an inert gas atmosphere. The residual hydrogen content of the calcined raw material was analyzed according to the general rule of methods for determining hydrogen content in metal materials (JIS Z2614: 1990), and the result was 20000 ppm. The calcined raw material was charged into a screw-type graphite crucible made of a material having a bulk density of 1.80 and an open pore ratio of 10%, and the screw was tightened while rotating a screw-type upper lid to seal the calcined raw material. The graphite crucible after sealing was filled in a hot isostatic pressing apparatus, and then heated and pressurized at a temperature of 700 ℃ and a pressure of 70MPa for 1 hour using argon gas, and at a temperature rise rate of 500 ℃ per hour, and heated and pressurized at a maximum reaching pressure of 190MPa and a maximum reaching temperature of 1800 ℃ and held at the maximum reaching temperature and pressure for 1 hour, and then cooled and depressurized to room temperature. The true density of the resulting bulk product was measured by a helium gas replacement pycnometer method using a densitometer AccuPyc1330-PCW manufactured by Shimadzu corporation, and the result was 2.17. Further, an SEM of the obtained vapor-phase-grown graphite is shown in fig. 62, an enlarged view thereof is shown in fig. 63, and flaky graphite crystals (multilayer graphene) extending from the inside to the outside are aggregated to form a block.

< flaky graphite Crystal, shrinkage thereof >

Example 18

The vapor-phase-grown graphite obtained in the immediately preceding example was pulverized in an agate mortar, and the pulverized sample was put into dimethylformamide to prepare a mixed solution having a graphite content of 5% by weight. After applying ultrasonic waves (at a frequency of 42kHz for 30 minutes) to the mixed solution by an ultrasonic washer, the solid matter was settled by centrifugal separation (at an acceleration of 700G for 30 minutes). Using the supernatant of the obtained solution, graphene dispersed in the solution was filtered with a fine mesh for TEM observation, and TEM observation was performed with respect to the components captured on the fine mesh. As a result of TEM observation, a large amount of the shrunken multilayer graphene (curtain-like product) shown in fig. 64 and 65 was observed. In addition, a large number of products (flaky graphite crystals, i.e., multilayer graphene) present in thin sheets as shown in fig. 66 were also observed. Fig. 67 shows a lattice image of an end portion of lamellar multi-layer graphene using TEM, and it was confirmed that about 10 graphene layers were stacked, and a multi-layer graphene laminate having a thickness of 3.5nm was obtained.

< graphite crystal masses obtained by partially cleaving flaky graphite crystals of the flaky graphite crystal masses of the present invention >

Example 19

5g of the crystalline flake graphite of the present invention obtained as sample No. 2 in example 1 was weighed in a glass Erlenmeyer flask, and a mixed solution of 80ml of concentrated sulfuric acid and 20ml of concentrated nitric acid was added thereto, followed by reaction for 24 hours while stirring with a Teflon (registered trademark) stirrer. In the bulk sample, starting at about 30 minutes after the start of the reaction, the sulfate ions intrude into the graphite interlayers and are gradually disintegrated by the formation of the graphite sulfate intercalation compound, and the fine particles are dispersed in the solution after the end of the reaction. The sample after the reaction was dried and then charged into a magnetic crucible made of ceramic, and the resultant was charged into an electric furnace heated to 700 ℃ together with the magnetic crucible, and subjected to a rapid heating treatment. By the rapid heat treatment in an electric furnace set at 700 ℃, the heat-treated sample expanded about 3 times in volume. Fig. 68 and 69 show the SEM of the sample after the heat treatment, but the heat treatment rapidly decomposes and releases sulfate ions from between the layers of the multilayer graphene, and a state in which the multilayer graphene is cleaved into thinner layers is observed.

< crystalline flake graphite >

Example 20

Pellet-shaped PET resin (average particle diameter about 3mm) was preliminarily fired at a maximum reaching temperature of 600 ℃ in an inert gas atmosphere. The calcined raw material (calcined raw material) is pulverized and classified to obtain a calcined raw material having an average particle diameter of about 10 to 100 μm. The residual hydrogen content was 22000 ppm. The calcined raw material was charged into a screw-type (triangular screw-type) graphite crucible made of a material having a bulk density of 1.80 and an open pore rate of 10%, and the screw was tightened while rotating a screw-type upper lid to seal the calcined raw material. After the graphite crucible was loaded in a hot isostatic pressing apparatus, the graphite crucible was heated and pressurized at a temperature and pressure of 600 ℃ and 70MPa for 1 hour using argon gas, and at a temperature rise rate of 500 ℃ per hour, the graphite crucible was heated and pressurized at a maximum reaching pressure of 190MPa and at maximum reaching temperatures of 1500 ℃, and the graphite crucible was held at the maximum reaching temperature and pressure for 1 hour, and then cooled and depressurized to room temperature. As the treated sample, a flaky graphite crystal mass (true density of 2.08, apparent density of 1.33, bulk density of 0.75, total porosity of 63.9) was obtained. An SEM of the surface of the flaky graphite crystal mass is shown in fig. 70. The graphite particles were composed of petaloid flaky graphite crystals having a size of several μm and an extremely thin thickness, and a plurality of these crystals were collected.

Example 21

Samples (examples 21-1 to 21-6) were obtained by treating in the same manner as in example 20, except that a phenol-formaldehyde resin (average particle size 20 μm) was used as a raw material instead of the PET resin, the raw material was not pulverized and classified, and the treatment conditions shown in table 5 were used.

[ Table 5]

TABLE 5

The true density, apparent density, bulk density and total porosity of each sample thus obtained are shown in table 6.

[ Table 6]

TABLE 6

Industrial applicability of the invention

The present invention can provide a flaky graphite crystal ingot in which flaky graphite crystals extending from the inside to the outside are aggregated, a one-dimensional shape nano-silicon material, and a graphite-silicon composite material containing the flaky graphite crystals and the one-dimensional shape nano-silicon material. They are all useful as electrode materials, highly exothermic materials, etc. for lithium ion batteries, hybrid capacitors, etc., and their production processes are all efficient and have high productivity.

Further, the present invention provides a flaky graphite crystal, and/or a wrinkled body and/or a rolled-up deformed body thereof. They are useful as transparent conductive films, conductive films and thermal conductive films, and additive materials of these.

Description of reference numerals

1 crucible cover

1a outer peripheral portion of the crucible cover

2 crucible body

2a inner wall of upper part of crucible body

3 preburning the raw materials

4 spacer

5 sleeve barrel

6 preburning raw material particles

6a gas

Surface of 6s calcined raw material particle

7 vapor-grown graphite

7a in-plane direction of hexagonal graphite mesh (a-axis direction of graphite crystal)

C-axis direction of 7c graphite crystal

Claims (24)

1. A method for producing a crystalline flake graphite block in which flaky graphite crystals extending outward from the inside are aggregated, comprising: preparing powder and granules of an organic compound which is calcined so as to contain residual hydrogen, placing the powder and granules in a closed container made of a heat-resistant material, and performing hot isostatic pressing treatment using a pressurized gas atmosphere together with the closed container, wherein the maximum temperature in the hot isostatic pressing treatment is 900 ℃ or higher and less than 2000 ℃.

2. The method of claim 1, wherein the peak arrival temperature is greater than 1000 ℃ and less than 2000 ℃.

3. The production method according to claim 1 or 2, wherein the sealed container made of a heat-resistant material is a graphite sealed container.

4. The production method according to any one of claims 1 to 3, wherein the residual hydrogen is 6500ppm or more.

5. The production method according to any one of claims 1 to 3, wherein the temperature of the pre-firing is 1000 ℃ or lower.

6. The production method according to any one of claims 1 to 5, wherein the graphite closed vessel is a screw-type closed vessel having an open porosity of less than 20% and a triangular screw.

7. The method according to any one of claims 1 to 6, wherein the organic compound is selected from the group consisting of starch, cellulose, protein, collagen, alginic acid, dammar resin, copal resin, rosin, gutta percha, natural rubber, cellulose-based resin, cellulose acetate, cellulose nitrate, cellulose acetate butyrate, casein plastic, soybean protein, phenol resin, urea resin, melamine resin, benzoguanamine resin, epoxy resin, diallyl phthalate resin, non- and polyester resin, bisphenol A-type epoxy resin, novolak-type epoxy resin, polyfunctional epoxy resin, alicyclic epoxy resin, alkyd resin, polyurethane resin, polyester resin, vinyl chloride resin, polyethylene, polypropylene, polystyrene, polyisoprene, butadiene, nylon, vinylon, acrylonitrile-based fiber, rayon, and mixtures thereof, Polyvinyl acetate, ABS resin, AS resin, acrylic resin, polyacetal, polyimide, polycarbonate, modified polyphenylene oxide, polyarylate, polysulfone, polyphenylene sulfide, polyether ether ketone, fluororesin, polyamideimide, silicone resin, petroleum asphalt, coal-based asphalt, petroleum coke, coal coke, carbon black, activated carbon, waste plastic, waste PET bottle, waste wood, waste plant, and biological waste.

8. The production method according to any one of claims 1 to 7, wherein the particulate organic compound is a phenol resin having an average particle diameter of 100 μm or less.

9. The production method according to any one of claims 1 to 8, wherein the hot isostatic pressing treatment is performed in a state in which a part or all of the periphery of the powder and/or granule of the calcined organic compound charged in the graphite closed container is covered with the spacer and the sleeve.

10. The manufacturing method according to claim 9, wherein the spacer and the sleeve are made of 1 or 2 or more selected from glassy carbon, diamond-like carbon, and amorphous carbon.

11. The production method according to any one of claims 1 to 10, wherein 1 or 2 or more carbon materials selected from carbon fibers, natural graphite, artificial graphite, glassy carbon, and amorphous carbon are mixed into the powder of the calcined organic compound.

12. A method for producing a graphite ingot in which flaky graphite crystals are partially cleaved, comprising: a step of preparing a graphite intercalation compound containing the flake graphite crystal mass obtained by the production method according to any one of claims 1 to 11 as a host material, and rapidly heating the compound.

13. A flaky graphite crystal mass is formed by assembling flaky graphite crystals extending from the inside to the outside.

14. A graphite crystal ingot obtained by partially cleaving the flaky graphite crystals of the flaky graphite crystal ingot of claim 13.

15. A method for manufacturing a one-dimensional nano silicon material comprises the following steps: preparing powder particles of an organic compound which is calcined so as to contain residual hydrogen, mixing the powder particles with silicon, placing the mixture in a closed container made of a heat-resistant material, and performing hot isostatic pressing treatment using a pressurized gas atmosphere together with the closed container, wherein the maximum reaching temperature in the hot isostatic pressing treatment is 1320 ℃ or higher and less than 2000 ℃.

16. A method for producing a graphite-silicon composite material comprising a crystalline flake graphite ingot in which crystalline flake graphite crystals extending outward from the inside are aggregated and a one-dimensional shape nano-silicon material, the method comprising: a method for producing a silicon-containing alloy material, which comprises preparing a powder of an organic compound calcined so as to contain residual hydrogen, mixing the powder with silicon, placing the mixture in a closed container made of a heat-resistant material, and subjecting the mixture to hot isostatic pressing treatment using a pressurized gas atmosphere together with the container, wherein the maximum temperature of the hot isostatic pressing treatment is 1320 ℃ or higher and less than 2000 ℃.

17. The method of claim 15 or 16, wherein the maximum reaching temperature is 1350 ℃ or higher and 1800 ℃ or lower.

18. The production method according to any one of claims 15 to 17, wherein the particle size of the powdery silicon is less than 500 μm.

19. A graphite-silicon composite material comprising a crystalline flake graphite block in which crystalline flake graphite extending outward from the inside is aggregated and a one-dimensional shape nano-silicon material.

20. A method for producing flaky graphite crystals dispersed in a solvent, and/or a rolled body and/or a rolled deformed body thereof, comprising: pulverizing an aggregated flake graphite crystal, dispersing the resultant in a solvent, applying ultrasonic waves, centrifuging, and collecting the supernatant.

21. A method for producing a flaky graphite crystal, and/or a crinkle and/or a rolled deformation thereof, comprising: a step of distilling the solvent from the flaky graphite crystal dispersed in the solvent, and/or the rolled body and/or the rolled-up deformation thereof as claimed in claim 20.

22. The production process according to claim 20 or 21, wherein the aggregated flaky graphite crystals comprising aggregated flaky graphite crystals are a flaky graphite crystal mass comprising aggregated flaky graphite crystals extending outward from the inside.

23. A flaky graphite crystal dispersed in a solvent, and/or a crinkle and/or a coil-like modification thereof, comprising multilayer graphene having a thickness of 10nm or less.

24. A flaky graphite crystal, and/or a crinkle and/or a coil-like deformation thereof, comprising multilayer graphene having a thickness of 10nm or less.