JP7195513B2 - A method of producing a graphene sheet consisting of a collection of graphene in which flat planes of graphene are overlapped and joined, and a method of covering the surface of the graphene sheet with a collection of fine particles of metal or insulating metal oxide. - Google Patents

Description

The present invention breaks the interlayer bonds of graphite crystals forming graphite particles in a container filled with methanol to produce a graphene mass consisting of the basal planes of the graphite crystals. Next, a graphene sheet composed of a group of graphenes in which the flat surfaces of the graphenes are overlapped and joined is manufactured on the bottom surface of the container in the shape of the bottom surface. Furthermore, it relates to a method of covering the surface of a graphene sheet with a collection of metal or insulating metal oxide fine particles. Note that graphene is a single-crystal material composed of a collection of carbon atoms that two-dimensionally form a network structure composed of hexagonal carbon atoms. In addition, in the present invention, a collection of thin sheet-like graphene in which the flat surfaces of graphene are directly overlapped and joined together is referred to as a graphene sheet. The graphite particles consist of only single crystals of graphite, and are the cheapest carbon material with 100% crystallization of graphite. A group of graphenes consisting of

In 2004, physicists at the University of Manchester, England, used cellophane tape to peel off a single crystallite from graphite, that is, the basal plane that forms a two-dimensional network of hexagonal carbon atoms, For the first time, we succeeded in extracting a planar material whose thickness is equal to the size of a carbon atom. This new material was called graphene. The 2010 Nobel Book of Physics was awarded for this research result.

Graphene is an extremely thin substance with a thickness corresponding to the size of a carbon atom, and is a completely new carbon material that has almost no mass. For this reason, it is attracting attention as a material that can be applied to a wide range of applications because it has physical properties that are far from those of conventional materials.
For example, the thinnest material with a thickness of 0.332 nm. It also has the widest surface area per unit mass of 3000 m ² /g. Furthermore, it has a large Young's modulus of 1020 GPa, and is the most stretchable and bendable material. In addition, it is the toughest substance with a high shear modulus of 440 GPa. Furthermore, the thermal conductivity is 19.5 W/Cm, which is 4.5 times higher than that of silver, which has the highest thermal conductivity among metals. Also, the current density exceeds 1000 times that of copper. Furthermore, it has an electrical conductivity that is only 23 times the resistivity of copper. In addition, the electron mobility is 15000 cm ² /volt·sec, which is one order of magnitude higher than the mobility of silicone of 1400 cm ² /volt·sec. Furthermore, it is a single crystal material with a melting point exceeding 3000° C., and is a material with extremely high heat resistance.

Graphene, on the other hand, is produced in a variety of ways. For example, the above-mentioned professor at the University of Manchester physically peeled graphene from graphite by hand. With this method, it is difficult to peel off a large amount of graphene in a short period of time, and what is peeled off does not necessarily become a single layer of graphite crystals, that is, graphene.
Further, Patent Document 1 describes a method of producing graphene by thermally decomposing a single crystal of silicon carbide. That is, silicon carbide is heated in an inert atmosphere to pyrolyze the surface. At this time, silicon, which has a relatively low sublimation temperature, preferentially sublimes, and graphene is generated from the remaining carbon. However, single crystal silicon carbide is a very expensive material. Furthermore, silicon is sublimated at a high temperature exceeding 1600° C. in a high vacuum atmosphere, but if even a small amount of silicon remains, graphene is not generated as a residue after thermal decomposition. As a result, the costs involved in producing single crystals of silicon carbide and pyrolyzing the single crystals are very high. Also, producing large quantities of graphene is even more expensive.
Furthermore, Patent Literature 2 describes a method of producing graphene by bringing a carbon-based material into contact with a sheet-like single-crystal graphitized metal catalyst and heat-treating in a reducing atmosphere. However, this manufacturing method cannot be said to be a cheap manufacturing method, and is not a manufacturing method excellent in mass productivity. First, the manufacturing cost of producing single crystal graphitized metal catalysts is much higher than single crystal silicon carbide. Second, the method of bringing a single-crystal graphitized metal catalyst into contact with a carbonaceous material is not suitable for mass production. Third, the method of reducing the graphitized metal catalyst at a high temperature exceeding 1000° C. in an atmosphere rich in nitrogen gas containing hydrogen gas results in high heat treatment costs. Therefore, it is more expensive to produce large amounts of graphene.

None of the methods for producing graphene to date is, first of all, a way to produce large amounts of graphene simultaneously in a cheap production process. Second, the graphene produced is not necessarily graphene. In other words, graphene is a single-crystal material consisting of a collection of carbon atoms that form a two-dimensional network structure of hexagonal carbon atoms. No graphene is produced. Furthermore, since the produced graphene is extremely thin and extremely light, it is difficult to identify it as graphene.
For this reason, the present inventors have found a method for producing a large amount of graphene in a very simple manner, in which all of the produced graphene is complete graphene (Patent Document 3). That is, it consists of only single crystals of graphite, the crystallization of graphite is advanced by 100%, and furthermore, lumps of natural graphite crystals, which are the cheapest carbon materials, are crushed, and from the crushed graphite crystals, flake graphite particles or A group of graphite particles selected from a group of massive graphite particles is spread in the gap between two parallel plate electrodes, an electric field is applied to the two parallel plate electrodes, and graphite particles are formed by the application of the electric field. In this method, the interlayer bonds of the graphite crystals are destroyed at the same time, and a large amount of graphene composed of the basal planes of the graphite crystals is produced. According to this production method, from only 1 g of scale-like graphite particles or massive graphite particles, graphene aggregates of up to 1.62×10 ¹³ pieces can be instantaneously obtained.

JP 2015-110485 A JP 2009-143799 A Patent No. 6166860

As explained in the third paragraph, since graphene has amazing physical properties that are completely different from conventional materials, research and development of various parts and Debye using graphene are being conducted. Therefore, if a method for producing a graphene sheet consisting of a collection of graphenes in which the graphene flat surfaces are overlapped and joined from a collection of graphenes manufactured by an inexpensive manufacturing method can be found, an inexpensive part using the graphene sheet or Practical use of devices progresses. Furthermore, if the surface of the graphene sheet can be covered with a collection of metal or insulating metal oxide fine particles, the graphene sheet with a conductive or insulating surface can be crimped to a base material or a component, and the base material Graphene sheet properties can be imparted to parts and parts.
On the other hand, although a large amount of graphene can be produced instantaneously by the production method according to Patent Document 3, no method has been found for producing a graphene sheet from this collection of graphene. Graphene is an extremely thin substance consisting of a single crystallite in which carbon atoms form a two-dimensional network structure consisting of hexagons, and is extremely lightweight and has almost no mass. For this reason, graphene produced by simultaneously breaking interlayer bonds of graphite crystals in graphite particles by applying an electric field in Patent Document 3 scatters very easily during and after production. Furthermore, since graphene is extremely thin, it has flat planes with an extremely large aspect ratio, which is the ratio of the crystal plane size to the thickness. In addition, since the graphite particles have a certain shape and the shapes of the graphite particles are not the same, the aspect ratio of the graphene produced by breaking the interlayer bonding of the graphite crystals in the graphite particles differs for each graphene. Therefore, in the manufacturing method in Patent Document 3, the flat surfaces of graphene easily overlap each other during the manufacture of graphene. Furthermore, the number of overlapping graphenes is not constant. In addition, it is extremely difficult to identify whether or not the flat surfaces overlap each other, and the only way to do so is by observation with an electron microscope. Furthermore, since the bonding strength between the flat surfaces of graphene with overlapping flat surfaces is weak, when a graphene sheet is produced using a collection of such graphene, the graphene sheet is separated at the portion where the flat surfaces overlap. .
Therefore, there are the following five problems to be solved in manufacturing a graphene sheet in which graphene flat surfaces are overlapped and joined.
First, a mass of graphene is produced in a container filled with a low-viscosity, low-boiling liquid. As a result, the graphene precipitated in the liquid does not scatter during and after the graphene production. However, graphene overlaps flat planes during fabrication.
Second, the graphene cluster is separated into individual graphene sheets in the container described above. This ensures that all the graphene is in contact with the liquid and subsequent processing does not directly overlap the flattened planes of the graphene.
Third, the graphene flat surfaces are overlapped on the bottom surface of the container with the liquid interposed therebetween. Further, the temperature of the container is raised to the boiling point of the liquid to vaporize the liquid to form a group of graphenes in which the flat surfaces overlap with each other on the bottom surface of the container. This makes it possible to manufacture a graphene sheet in which the flat surfaces are overlapped and bonded.
Fourth, the upper plane of the graphene aggregate is evenly compressed to generate frictional heat in the overlapping portions of the flat surfaces of the graphene, and the flat surfaces of the graphene are joined by the frictional heat, and the graphene A graphene sheet consisting of a collection of is formed on the bottom surface of the container in the shape of the bottom surface.
Fifth, the treatments in the four steps described above are all extremely simple treatments, and the materials used are general-purpose, inexpensive materials. As a result, a group of inexpensive graphite particles is used to manufacture a group of graphene by an inexpensive manufacturing method, and a graphene sheet is manufactured by an inexpensive method. As a result, inexpensive graphene sheets can be manufactured.
The problems to be solved in manufacturing the graphene sheet are the above five problems.
Furthermore, there are the following three problems to be solved in covering the surface of the graphene sheet described above with a collection of metal or insulating metal oxide fine particles.
First, the surface of the graphene sheet formed in the shape of the bottom surface of the container is covered with a collection of fine particles made of metal or insulating metal oxide. Therefore, it is necessary to liquefy the metal or insulating metal oxide.
Second, a graphene sheet whose surface is covered with a collection of fine particles made of metal or insulating metal oxide can be removed from the container.
Thirdly, the process of covering the surface of the graphene sheet with a collection of fine particles made of metal or insulating metal oxide is an extremely simple process, and the material used is a general-purpose and inexpensive material.
As a result, the surface of the graphene sheet can be covered with a collection of fine particles made of a metal or an insulating metal oxide by an inexpensive method, and the surface of the graphene sheet can be coated with fine particles made of a metal or an insulating metal oxide at a low cost. can be covered with a collection of
The above three problems are to be solved in order to cover the surface of the graphene sheet with a collection of fine particles made of metal or insulating metal oxide.
The problems to be solved by the present invention are the above eight problems.

A method for producing a graphene sheet consisting of a collection of graphene in which the flat planes of graphene overlap and are joined,
A collection of scale-like graphite particles or a collection of massive graphite particles is evenly spread on the surface of one of the two parallel-plate electrodes, and the parallel-plate electrode is immersed in methanol filled in a container. Further, the other parallel plate electrode is superimposed on the one parallel plate electrode, and the two parallel plate electrodes are separated via the collection of the scale-like graphite particles or the collection of the massive graphite particles. , the two spaced apart parallel plate electrodes are immersed in the methanol;
After that, a DC potential difference is applied across the gap between the two parallel plate electrodes, whereby an electric field corresponding to the value obtained by dividing the potential difference by the gap between the two parallel plate electrodes is generated. , a coulomb sufficient to break the interlayer bonding of the basal planes of graphite crystals for all of the graphite particles by the application of the electric field applied to the cluster of flake graphite particles or the cluster of massive graphite particles. A force is simultaneously applied to all the π electrons responsible for the interlaminar bonds of the basal planes forming the graphite particles, thereby causing all the interlaminar bonds of the basal planes forming the flake graphite particles or the massive graphite particles. are destroyed at the same time, and a group of graphene corresponding to the basal plane is produced in the gap between the two parallel plate electrodes.
After that, the gap between the two parallel plate electrodes is widened, the two parallel plate electrodes are tilted in the methanol, and further vibration acceleration is repeatedly applied to the container in three directions, left and right, front and back, and up and down. , transferring the graphene mass from the gap between the two parallel plate electrodes into the methanol, after which the two parallel plate electrodes are removed from the container;
Furthermore, the homogenizer device is operated in methanol in the container, and the collection of graphene is repeatedly impacted through the methanol, and the collection of graphene is separated into individual graphenes in the methanol. After that, remove the homogenizer device from the container,
Further, vibrational acceleration in three directions of front and back, left and right, and up and down is repeatedly applied to the container, and a collection of the graphene in which the flat surfaces of the graphene are overlapped with methanol is formed on the bottom surface of the container as the shape of the bottom surface. do,
After that, the container is heated to the boiling point of the methanol to vaporize the methanol, and a collection of the graphene in which the flat surfaces of the graphene overlap each other is formed on the bottom surface of the container as the shape of the bottom surface.
After that, the upper plane of the graphene aggregate is evenly compressed to generate frictional heat at the portion where the flat surfaces of the graphene overlap each other, and the flat surfaces of the graphene are bonded to each other by the frictional heat, and the graphene A graphene sheet consisting of a collection of graphenes in which the flat surfaces of graphene are overlapped and bonded is formed on the bottom surface of the container in the shape of the bottom surface, and a graphene consisting of a collection of graphenes in which the flat surfaces of graphene are overlapped and bonded A method of manufacturing a sheet.

According to the present invention, the method for producing a graphene sheet composed of a group of graphenes in which flat planes of graphene are overlapped and joined includes the following four steps.
First, in methanol, a graphene mass is produced from a mass of graphite particles. That is, a collection of scale-like graphite particles or a collection of massive graphite particles spread in the gap between two parallel plate electrodes is immersed in methanol, which is an insulator, and a direct current potential difference is generated between the two parallel plate electrodes. is applied. As a result, an electric field corresponding to a value obtained by dividing the potential difference by the size of the gap between the two parallel plate electrodes is generated in the electrode gap where the group of flake graphite particles or the group of massive graphite particles exists. This electric field simultaneously imparts a Coulomb force sufficient to break the interlayer bonding of the basal planes of graphite crystals to all the π electrons responsible for the interlayer bonding of the basal planes of all the graphite particles. As a result, the π electrons are released from the constraint on the π orbital, and all the π electrons leave the π orbital and become free electrons. In other words, when the Coulomb force acting on the π-electrons is given to the π-electrons as a force greater than the interaction of the π-orbitals, the π-electrons are released from the π-orbital constraints and become free electrons. As a result, all the π electrons responsible for the interlayer bonds of the basal planes are absent from the π orbitals, and for all the graphite particles, all the interlayer bonds of the basal planes composed of the graphite crystals forming the graphite particles are simultaneously be destroyed. As a result, a collection of basal planes, that is, a collection of graphene is instantly produced in the gap between the two parallel plate electrodes. The manufactured graphene is an intrinsic substance without impurities, consisting only of graphite crystals. Since the two parallel plate electrodes are immersed in methanol, the aggregate of graphene deposited in the gap between the two parallel plate electrodes does not scatter. This solved the first of the five problems in producing graphene sheets described in paragraph 7.
When a potential difference is applied between two parallel plate electrodes immersed in methanol, which is an insulator, an electric field is generated in the gap between the two parallel plate electrodes. That is, methanol is an insulator with a specific resistance of 3 megaΩ·cm or more and a dielectric constant of 33. Ethanol is also an insulator with a dielectric constant of 24. The electrical conductivity of ethanol is 7.5×10 ⁻⁶ S/m, and the electrical conductivity of flake graphite particles is 43.9 S/m. Therefore, ethanol is an insulator whose electric conductivity is 1.7×10 ⁷ times lower than that of flake graphite particles, which are conductors.
Second, the graphene mass is separated into individual graphenes in methanol. That is, the graphene deposited in the narrow gap between the two parallel plate electrodes is separated into individual graphenes in methanol because the flat surfaces overlap each other when deposited. For this purpose, first, the gap between the two parallel plate electrodes is expanded in methanol, then tilted in methanol, and then vibration acceleration in three directions is applied to the container filled with methanol. This causes the graphene clusters to migrate from the gap between the two parallel plate electrodes into the methanol. After that, the two parallel plate electrodes are taken out from the container. The homogenizer apparatus is then run in methanol to repeatedly bombard the graphene mass through the methanol. On the other hand, when the flat surfaces of graphene are bonded to each other, the flat surfaces simply overlap each other, and the bonding force between the flat surfaces is extremely small. Furthermore, due to the low viscosity and low molecular weight of methanol, the impact applied to methanol is only slightly consumed by the molecular vibration of methanol, and most of the impact energy is not absorbed and is added to the graphene aggregates. When this impact is applied to the portion where the flat surfaces overlap each other, the overlapping flat surfaces are easily separated, and methanol enters the gaps between the separated graphenes. Therefore, when a group of graphene is repeatedly bombarded, it is separated into individual graphene sheets in methanol, and the flattened planes of the separated graphene come into contact with methanol. In addition, when an ultrasonic homogenizer is used, the generation and disappearance of a huge number of extremely fine bubbles smaller than the flat plane of graphene by one order or more are synchronous with the vibration period of the vibration frequency of the ultrasonic waves. Accordingly, the shock wave generated by the bursting of a huge number of bubbles, which is continuously repeated in methanol (this phenomenon is called cavitation), is repeatedly applied to the entire graphene mass through the methanol. When a shock wave is applied to a portion where the flat surfaces overlap each other, the overlapping flat surfaces are separated, methanol enters the gaps between the separated graphenes, and the graphene is separated into individual graphenes in a short period of time. Graphene produced by breaking interlayer bonds on the basal planes of graphite particles is an intrinsic substance that is free of impurities and consists only of graphite crystals. After that, the graphene separated into individual graphenes was also free of impurities because the treatment in methanol was continued, and it is an intrinsic substance consisting of graphite crystals only.
This solved the second of the five problems in producing graphene sheets described in paragraph 7. In addition, whether or not the graphene was separated into individual sheets by the operation of the homogenizer was determined by taking out multiple samples from the methanol and observing the multiple samples with an electron microscope. determine whether or not Based on this result, the operating conditions and operating time of the homogenizer are obtained in advance.
Third, the container is repeatedly subjected to vibration acceleration in three directions: back and forth, left and right, and up and down, so that a group of graphene in which the flat surfaces of the graphene are overlapped with each other via methanol is formed on the bottom surface of the container as the shape of the bottom surface. . In other words, the aspect ratio of graphene is extremely large, and the flat surfaces of the graphene separated into individual sheets are in contact with methanol. moves in the methanol, the graphene spreads over the entire bottom surface of the container, and the flat planes overlap through the methanol. When the application of vibration to the container is stopped, a collection of graphene in which the flat surfaces are overlapped with each other via methanol is formed on the bottom surface of the container in the shape of the bottom surface. Thereafter, when the temperature of the container is raised to the boiling point of methanol to evaporate the methanol, a collection of graphene in which the flat surfaces overlap each other is formed on the bottom surface of the container in the shape of the bottom surface. This solved the third of the five problems in producing graphene sheets described in paragraph 7. The vaporized methanol is collected by a collector and reused.
Fourth, the plane above the group of graphene formed on the bottom surface of the container is evenly compressed to generate frictional heat at the portion where the graphene flat surfaces overlap each other, and the frictional heat causes the flat surfaces of the graphene to separate. A graphene sheet is formed on the bottom surface of the container in the shape of the bottom surface by bonding the flat surfaces of the graphene to each other so that the flat surfaces of the graphene are bonded together. That is, graphene has a breaking strength of 42 N/m, which is 100 times or more that of steel. Therefore, even if a large load is applied to the plane above the group of graphene formed on the bottom surface of the container, the flat plane of the graphene is neither deformed nor destroyed. Therefore, when the upper plane of the graphene cluster formed on the bottom surface of the container is evenly compressed, the applied compressive stress is not reduced, and the compressive stress is applied to the overlapping portions of the graphene flat planes. , frictional heat is generated, the flat surfaces of graphene are bonded by the frictional heat, and a graphene sheet consisting of a collection of graphenes in which the flat surfaces of graphene are overlapped and bonded is formed on the bottom surface of the container in the shape of the bottom surface. be done. As described above, graphene is an intrinsic substance that has no impurities and consists only of graphite crystals. Since the graphene flat surfaces are bonded by frictional heat, the graphene flat surfaces are firmly bonded. This solved the fourth of the five problems in producing graphene sheets described in paragraph 7.
In the graphene sheet, the flat surfaces of the graphene are joined together by frictional heat, so the graphene is joined with a certain bonding force. Therefore, when vibration acceleration in three directions, ie, left-right, back-and-forth, and up-and-down directions is applied for a short time to the container in which the graphene sheet is formed on the bottom surface of the container, the graphene sheet can be taken out from the container. In addition, the graphene sheet taken out can be handled. Note that the vibration acceleration applied to the container is approximately 0.2 G because the graphene sheet is extremely lightweight.
By the way, methanol used for producing graphene sheets is a general-purpose, inexpensive industrial chemical. Graphite particles are also an inexpensive industrial material. In addition, the above four steps consist of extremely simple processing. Therefore, according to this method, when four extremely simple steps are continuously performed using inexpensive graphite particles and methanol, a graphene sheet in which the flat surfaces of graphene are overlapped and bonded is formed on the bottom surface of the container. formed as the shape of the slump. This solved the fifth problem of the five problems in producing graphene sheets described in paragraph 7, and solved all the problems.
The graphene sheet manufactured by the manufacturing method described above has the following effects.
First, with a thickness of 0.332 nm, which corresponds to the size of a carbon atom, graphene is extremely lightweight and has almost no mass. In addition, since the thickness is extremely thin, the presence of graphene cannot be visually confirmed. Therefore, it is difficult to handle the graphene sheet by sheet. On the other hand, since a graphene sheet in which graphenes are bonded via a flat surface has a constant area and a constant thickness, the graphene sheet can be handled one by one. Since this graphene sheet is composed only of graphene, it has the properties of graphene. Furthermore, graphene sheets are inexpensive industrial materials that can be manufactured using inexpensive materials and by inexpensive methods. For this reason, applications to various industrial products using graphene sheets are being explored.
Second, a graphene sheet having the shape of the bottom surface is produced on the bottom surface of the container. Therefore, a submicron-thick graphene sheet can be produced, and the shape and area of the graphene sheet can be freely changed according to the shape of the bottom surface of the container. For this reason, graphene sheets, which are excellent in both thermal conductivity and electrical conductivity, can be used in any size, shape, and thickness, from small-area electrodes and contacts, to long and narrow wiring patterns, and large-area thermal conductive sheets. , can be freely produced as a graphene sheet consisting of the properties of graphene.
Third, graphene sheets are excellent in both thermal conductivity and electrical conductivity. That is, as described above, graphene has thermal conductivity equivalent to 4.5 times the thermal conductivity of silver and electrical conductivity equivalent to only 23 times the specific resistance of copper. Therefore, a graphene sheet in which the flat surfaces of graphene are bonded together has thermal conductivity equivalent to 4.5 times the thermal conductivity of silver and electrical conductivity equivalent to only 23 times the specific resistance of copper. . As a result, the graphene sheets have better thermal conductivity than silver and electrical conductivity close to that of metals.
Fourthly, since the graphene sheets, which are intrinsic substances consisting only of graphite crystals without impurities, are bonded to each other by frictional heat through the flat surfaces, the graphenes are strongly bonded to each other. In addition, the gap between graphenes is narrower than 0.332 nm, which corresponds to the thickness of graphene. For this reason, no substance can enter the gaps between the graphenes. Furthermore, the graphene sheet is composed only of graphene having a melting point exceeding 3000° C., and has the heat resistance of graphene. Therefore, the graphene sheet does not change over time no matter what environment it is used in. Therefore, graphene sheets having the properties of graphene are used as industrial materials in various fields.
Here, in the first treatment, an electric field is applied across the gap between the two parallel plate electrodes to form graphite grains spread in the gap between the two parallel plate electrodes. explain the phenomenon of destruction at the same time.
A carbon atom forming a graphite crystal in a graphite particle has four valence electrons. Three of these valence electrons are the σ electrons that form the basal plane, ie graphene. The σ electrons are covalently bonded to the σ electrons of three adjacent carbon atoms on the basal plane at an angle of 120 degrees to form a two-dimensional strong hexagonal network structure. The remaining one valence electron is a π electron and exists on a π orbital extending in a direction perpendicular to the basal plane. These π electrons bond with π electrons of carbon atoms adjacent in the vertical direction perpendicular to the basal plane with weak bonding force, and the basal plane is layered on the basis of this weak bonding force. That is, the basal planes, that is, graphene, are bonded to each other in layers by the interaction of π orbitals, which are weak bonding forces. For this reason, the graphite particles have the property of being easily peeled off at the base surface composed of graphite crystals, that is, they have mechanical anisotropy. This mechanical anisotropy is well known as the lubricity of graphite particles.
When an electric field is applied to such graphite particles, a Coulomb force due to the electric field acts on all π electrons. When the Coulomb force acting on the π-electrons acts on the π-electrons as a larger force than the π-orbital interaction acting on the π-electrons, the π-electrons are released from the π-orbital restraint. As a result, all π electrons leave the π orbit and become free electrons. As a result, all the .pi.-electrons responsible for the interlayer bonds on the basal plane are no longer on the .pi.-orbitals, so that all the interlayer bonds on the basal plane are destroyed at the same time. That is, when the π electrons move by the Coulomb force F over the interlayer distance b on the basal plane, the π electrons perform work W (W=b·F). This work W is 35 millielectron volts, which is the magnitude of the interaction of the π orbital per atom acting on π electrons (electron volt is a unit that expresses the magnitude of the energy possessed by an electron, and 1 electron volt is 1. (corresponding to 62×10 ⁻¹⁹ joules), the π-electrons are released from the constraints of the π-orbital interactions and become free electrons. For example, when the gap between two parallel plate electrodes is 100 μm and a DC potential difference of 10.6 kilovolts or more is applied to the gap between the electrodes, the interlayer bond on the basal plane is destroyed instantly. In this way, a large amount of graphene can be produced inexpensively by a very simple means of applying an electric field to a group of inexpensive graphite particles. Also, since all of the interlayer bonds on the basal plane are broken at the same time, the resulting fine material is reliably graphene, the basal plane made of graphite crystals.
The term "aggregate of graphite particles" as used herein refers to an aggregate of relatively small amounts of graphite particles of about 1 g to 100 g. That is, flake graphite particles or massive graphite particles are fine particles having a bulk density of 0.2-0.5 g/cm ³ and a particle size distribution of 1-300 microns. Therefore, it is easy to cover the gap between the two parallel plate electrodes with a group of graphite particles, and it is also easy to apply a potential difference to the two parallel plate electrodes. When a potential difference is applied across the gap between the two parallel plate electrodes, an electric field is generated in all areas where the graphite particles are pulled together. This electric field acts on the π-electrons as a Coulomb force greater than the π-orbital interaction, and the π-electrons are released from the π-orbital restraints and become free electrons. As a result, all of the basal plane interlayer bonds in the graphite particles are broken simultaneously, producing clusters of graphene in the gap between the two parallel plate electrodes.
Now, arithmetically determine the number of graphenes dispersed in the suspension. Here, we assume that all graphite particles consist of spheres with a diameter of 25 microns, and since the true density of graphite is 2.25×10 ³ kg/m ³ , the weight of one graphite particle is is only 1.84×10 ⁻⁸ g. In addition, assuming that the average thickness of graphite particles is 10 microns, the interlayer distance is 3.354 angstroms, so 297,265 graphenes are stacked in a scale-like graphite particle having a thickness of 10 microns. . Therefore, by breaking all the basal plane interlayer bonds, 297,265 graphene clusters can be obtained from just one spherical graphite particle. For this reason, when all the interlayer bonds on the basal plane are broken for a mass of only 1 g of spherical graphite particles, a mass of graphene consisting of 1.62×10 ¹³ particles is obtained. Therefore, according to this production method, a huge number of graphene aggregates can be obtained from a small amount of aggregates of graphite particles.

The method of covering the surface of the graphene sheet described in paragraph 8 with a collection of fine metal particles made of any metal of silver, copper, gold, or aluminum,
A metal compound in which any metal of silver, copper, gold, or aluminum is deposited by thermal decomposition is dispersed in methanol to prepare a methanol dispersion, and the methanol dispersion is added to the graphene sheet described in paragraph 8 of the container. The container formed on the bottom surface is filled with the graphene sheet, and the container is repeatedly subjected to vibration acceleration in three directions: left, right, front and back, and up and down, so that the surface of the graphene sheet is brought into contact with the methanol dispersion.
After that, the container is heated to a temperature at which the metal compound is thermally decomposed, whereby the methanol is first vaporized, and a collection of fine crystals of the metal compound precipitates all at once on the surface of the graphene sheet. After that, the fine crystals of the metal compound are thermally decomposed, and on the surface of the graphene sheet, a collection of granular metal fine particles made of any metal of silver, copper, gold, or aluminum precipitates all at once, The granular metal fine particles are metallically bonded at the sites where they contact each other, and the surface of the graphene sheet is covered with a collection of metal fine particles made of any metal of silver, copper, gold, or aluminum that is metallically bonded. A method of covering the surface of the graphene sheet described in paragraph 8 with a collection of fine metal particles made of any one of silver, copper, gold, and aluminum.

That is, when a container filled with a graphene sheet and a methanol dispersion of a metal compound is heated to a temperature at which the metal compound is thermally decomposed, the methanol is first vaporized, and fine crystals of the metal compound are formed on the surface of the graphene sheet. clusters precipitate all at once, and clusters of fine crystals cover the graphene sheet. That is, in the methanol dispersion of the metal compound, the metal compound is dispersed in methanol in a molecular state, so when the methanol is vaporized from the methanol dispersion, a collection of fine crystals of the metal compound is formed all at once on the surface of the graphene sheet. and covers the surface of the graphene sheet. Note that the size of the fine crystals is close to the size of the precipitated fine particles. Next, when the metal compound reaches a temperature at which thermal decomposition begins, the metal compound decomposes into an inorganic or organic substance and a metal. Since the density of the inorganic or organic matter is lower than that of the metal, the inorganic or organic matter precipitates in the upper layer and the metal in the lower layer. Aggregates of granular metal fine particles made of silver, copper, gold, or aluminum with a size of 60 nm are deposited all at once on the surface of the graphene sheet, covering the surface of the graphene sheet. Since these fine metal particles are in an active state without impurities, metal bonding occurs at the sites where they come into contact with each other. For this reason, the collection of metal fine particles deposited on the surface of the graphene sheet is metallically bonded at the sites where they are in contact with each other, and the collection of the metal microparticles bonded to each other covers the surface of the graphene sheet. When the amount of the metal compound dispersed in methanol increases, the amount of deposited metal fine particles increases, and as a result, the number of metal fine particles deposited on the surface of the graphene sheet increases, and the clusters of the metal fine particles that are metal-bonded are stacked, and the stacked metal particles The surface of the graphene sheet is covered with clusters of fine particles. As a result, the first problem among the three problems in covering the surface of the graphene sheet described in paragraph 7 with a collection of metal fine particles was solved. The thermal conductivity and electrical conductivity of metals are superior in the order of silver, copper, gold and aluminum. Moreover, all of these metals are soft metals with low hardness.
On the other hand, since the entire surface of the graphene sheet is covered with a collection of metal-bonded fine metal particles, the collection of metal-bonded metal fine particles covers the graphene sheet with a certain bonding force. In addition, since the graphenes are bonded to each other by frictional heat through the flat surfaces of the graphenes, the graphene sheets also have a certain bonding force. Therefore, when the graphene sheet is taken out from the container, the graphene sheet is dissociated from the container and the graphene sheet can be taken out from the container by applying vibration acceleration in the three directions of front and back, left and right, and up and down for a short time. In addition, the graphene sheet taken out can be handled. Note that the vibration acceleration applied to the container is approximately 0.4 G because the graphene sheet is extremely lightweight.
As a result, the second problem among the three problems in covering the surface of the graphene sheet described in paragraph 7 with a group of fine metal particles was solved.
The graphene sheet manufactured by the manufacturing method described above has the following effects.
First, a graphene sheet having the shape of the bottom surface is produced on the bottom surface of the container. Therefore, a submicron-thick graphene sheet can be produced, and the shape and area of the graphene sheet can be freely changed according to the shape of the bottom surface of the container. For this reason, graphene sheets, which are excellent in both thermal conductivity and electrical conductivity, can be used in any size, shape, and thickness, from small-area electrodes and contacts, to long and narrow wiring patterns, and large-area thermal conductive sheets. It can be freely manufactured as a graphene sheet.
Second, graphene sheets are excellent in both thermal conductivity and electrical conductivity. That is, as described above, graphene has thermal conductivity equivalent to 4.5 times the thermal conductivity of silver and electrical conductivity equivalent to only 23 times the specific resistance of copper. Therefore, a graphene sheet covered with a collection of fine metal particles made of silver, copper, gold, or aluminum has a relatively high thermal conductivity, that is, prefers flat surfaces of graphene to which heat is easily conducted. As a result, the current flows preferentially to the group of fine metal particles that have relatively high electrical conductivity, that is, to which the current flows easily. As a result, the graphene sheets have better thermal conductivity than silver and electrical conductivity close to that of metals. Note that the specific resistance of aluminum is 1.6 times the specific resistance of copper, and the conductivity of aluminum is higher than that of graphene.
Third, the entire surface of the graphene sheet is covered with a collection of fine metal particles composed of soft metals of 40-60 nm. It has lubricating properties.
Fourth, since the two planes of the graphene sheet are covered with clusters of fine metal particles, the graphene sheet can be crimped to parts or substrates. In other words, metals such as silver, copper, gold, and aluminum, which are excellent in both thermal conductivity and electrical conductivity, are soft metals with low hardness. The aggregates of the metal fine particles formed on the surface are plastically deformed or elastically deformed into the surface of the component or the base material, and bite into or come into pressure contact with the surface of the component or the base material, and the graphene sheet is crimped to the component or the base material. For this reason, the graphene sheet can be integrated with the part or the base material by pressure bonding, and both the properties of thermal conductivity and electrical conductivity can be imparted to the part or the base material.
Fifth, a metal compound that deposits silver, copper, gold, or aluminum by thermal decomposition is a general-purpose chemical for industrial use. It is covered with a collection of fine metal particles made of copper, gold, or aluminum. Therefore, using an inexpensive material and at a low cost, the flat surfaces of graphene having an arbitrary size, shape, and thickness are covered with a collection of fine metal particles made of silver, copper, gold, or aluminum. A fused graphene sheet can optionally be fabricated on the bottom surface of the container.
As a result, the third problem among the three problems in covering the surface of the graphene sheet described in paragraph 7 with a collection of metal fine particles was solved, and all the problems were solved.

The method of covering the surface of the graphene sheet described in paragraph 10 with a collection of fine metal particles made of any metal of silver, copper, gold, or aluminum,
A metal complex composed of an inorganic metal compound having a metal complex ion in which a ligand composed of an inorganic ion or an inorganic molecule is coordinated to a metal ion composed of a metal of silver, copper, gold, or aluminum, Any one of the metals silver, copper, gold, or aluminum described in paragraph 10 is used as a metal compound that is deposited by thermal decomposition, and the surface of the graphene sheet is treated with silver, copper, gold, or aluminum according to the method described in paragraph 10. A method of covering with a collection of fine metal particles composed of any metal such as aluminum.

In other words, when a metal complex composed of an inorganic metal compound having a metal complex ion in which a ligand composed of an inorganic ion or an inorganic molecule is coordinated to a metal ion is heat-treated in a reducing atmosphere, the metal transforms at 180-220°C. Precipitate. That is, when a metal complex composed of an inorganic metal compound is heat-treated in a reducing atmosphere, it is decomposed into an inorganic substance and a metal, and the inorganic substance takes away the heat of vaporization and vaporizes. to terminate the pyrolysis reaction.
That is, among the ions constituting the metal complex, the metal ion located in the center of the molecule is the largest, and the distance between the metal ion and the ligand is the longest. When this metal complex is heat-treated in a reducing atmosphere, the coordination bonds where metal ions bond with ligands are first cleaved and decomposed into metals and inorganic substances. When the temperature rises further, the inorganic material takes the heat of vaporization and vaporizes, and when the vaporization of the inorganic material is completed, the metal precipitates. Since metal complexes composed of such inorganic metal compounds have a small molecular weight, the vaporization of inorganic substances is completed at 180 to 220 ° C., and the temperature at which metal deposits is the lowest among the temperatures at which metal deposits due to thermal decomposition of metal compounds. .
In addition, metal complex ions in which inorganic molecules or inorganic ions serve as ligands and are coordinated to metal ions are easier to synthesize than other metal complex ions. Examples of such metal complex ions include ammine metal complex ions that coordinate to metal ions with ammonia _NH3 as a ligand, and aqua metal complex ions that coordinate to metal ions with water _H2O as a ligand. A complex ion, a hydroxo metal complex ion that is coordinated to a metal ion with a hydroxyl group OH ^- as a ligand, a chloride ion Cl ^- , or a metal ion with a chloride ion Cl ^- and ammonia NH ₃ as a ligand There are chloro metal complex ions that coordinate to . All of these ligands have small molecular weights. Furthermore, metal complexes composed of inorganic salts such as chlorides, sulfates, and nitrates having such metal complex ions have a small molecular weight of the inorganic salts. Therefore, the vaporization of the inorganic matter is completed within the temperature range of 180-220° C., and the metal is deposited. The temperature at which this metal is deposited is the lowest among the temperatures at which metal is deposited by thermal decomposition of metal compounds.
Therefore, the method of covering the surface of the graphene sheet described in paragraph 10 with a collection of fine metal particles made of any of silver, copper, gold, or aluminum is thermally decomposed into silver, copper, gold, or aluminum. As a metal compound for depositing a metal, an inorganic metal compound in which a ligand composed of inorganic ions or inorganic molecules is coordinated to a metal ion composed of any of silver, copper, gold, or aluminum Using a metal complex of silver, copper , gold, or aluminum.

The method of covering the surface of the graphene sheet described in paragraph 10 with a collection of fine metal particles made of any metal of silver, copper, gold, or aluminum,
The first feature is that the oxygen ion that constitutes the carboxyl group of the carboxylic acid is covalently bonded to a metal ion made of a metal such as silver, copper, gold, or aluminum, and the second feature is that the carboxylic acid is a saturated fatty acid. A carboxylic acid metal compound having the characteristics described in paragraph 10 is used as a metal compound in which any metal of silver, copper, gold, or aluminum described in paragraph 10 is deposited by thermal decomposition, and according to the method described in paragraph 10, a graphene sheet A method of covering the surface of a metal with a collection of fine metal particles made of any of silver, copper, gold, or aluminum.

In other words, a metal carboxylate compound having both the first feature that the oxygen ion constituting the carboxyl group of the carboxylic acid is covalently bonded to the metal ion and the second feature that the carboxylic acid is a saturated fatty acid has the highest metal ion content. It is a large ion, and the distance between the oxygen ion and the metal ion that constitute the carboxyl group is longer than the distance between other ions. When a carboxylic acid metal compound having such molecular structural features is heat-treated in an air atmosphere, when the boiling point of the carboxylic acid is exceeded, the bond between the oxygen ion and the metal ion constituting the carboxyl group is first broken, and the carboxylic acid and metal. When the carboxylic acid is composed of a saturated fatty acid, it does not have an unsaturated structure in which carbon atoms are excessive with respect to hydrogen atoms. Accordingly, the carboxylic acid takes the heat of vaporization and vaporizes, and when the vaporization is completed, the metal is deposited.
Such metal carboxylate compounds include metal octylate compounds, metal laurate compounds, metal stearate compounds, and the like. Note that octylic acid has a short chain length and a low boiling point of 228° C. because the hydrocarbon has a branched structure. In addition, carboxylic acids whose hydrocarbons have a straight chain structure have a lower boiling point as the molecular weight of the carboxylic acid is smaller, that is, as the straight chain is shorter, the boiling point of lauric acid is 296 ° C. 361°C. Therefore, these carboxylic acid metal compounds complete thermal decomposition at a temperature of 290 to 430° C. in an air atmosphere, depending on the above-mentioned boiling point.
In addition, since the carboxylic acid metal compound composed of unsaturated fatty acid has an excess of carbon atoms with respect to hydrogen atoms as compared with the carboxylic acid metal compound composed of saturated fatty acid, it is thermally decomposed into a metal oxide such as copper oleate. In the case of (2), cuprous oxide Cu ₂ O and cupric oxide CuO are deposited simultaneously, and a treatment for reducing cuprous oxide Cu ₂ O and cupric oxide CuO to copper is required. In particular, cuprous oxide Cu ₂ O is once oxidized to cupric oxide CuO in an atmosphere richer in oxygen than the atmosphere, and then reduced to copper in a reducing atmosphere, resulting in increased processing costs.
In addition, metal carboxylate compounds are inexpensive industrial chemicals that can be easily synthesized. That is, when a carboxylic acid, which is the most widely used organic acid, is reacted with a strong alkali, an alkali metal carboxylate compound is produced, and when an alkali metal carboxylate is reacted with an inorganic metal compound, carboxylic acids composed of various metals are produced. A metal compound is synthesized. Therefore, it is the most inexpensive organometallic compound among organometallic compounds. Therefore, although the heat treatment temperature is higher than that of the metal complex made of the inorganic metal compound described in paragraph 15, the metal compound is less expensive than the metal complex.
Therefore, the method of covering the surface of the graphene sheet described in paragraph 10 with a collection of fine metal particles made of any of silver, copper, gold, or aluminum is thermally decomposed into silver, copper, gold, or aluminum. A first feature that the oxygen ion constituting the carboxyl group of the carboxylic acid is covalently bonded to the metal ion composed of any one of silver, copper, gold, and aluminum as the metal compound for depositing the metal, and The surface of the graphene sheet described in paragraph 10 is coated with fine metal particles made of any one of silver, copper, gold, and aluminum using a carboxylic acid metal compound having the second feature that the carboxylic acid is a saturated fatty acid. According to the method of covering with a collection of metal particles, the surface of a graphene sheet is covered with a collection of fine metal particles made of any one of silver, copper, gold, and aluminum.

The method of covering the surface of the graphene sheet described in paragraph 8 with a collection of fine particles made of an insulating metal oxide,
A metal compound in which an insulating metal oxide is deposited by thermal decomposition is dispersed in methanol to prepare a methanol dispersion, and a graphene sheet produced from the methanol dispersion by the method described in paragraph 8 is formed on the bottom of the container. The container is filled, and the container is repeatedly subjected to vibration acceleration in three directions: left and right, front and back, and up and down, so that the surface of the graphene sheet is brought into contact with the methanol dispersion.
After that, the container is heated to a temperature at which the metal compound is thermally decomposed, whereby the methanol is first vaporized, and a collection of fine crystals of the metal compound precipitates all at once on the surface of the graphene sheet. After that, the fine crystals of the metal compound are thermally decomposed, and a collection of fine particles of the insulating metal oxide is precipitated on the surface of the graphene sheet all at once, and the fine particles of the insulating metal oxide are deposited on the surface of the graphene sheet. The graphene sheet whose surface is covered with clusters is formed on the bottom surface of the container in the shape of the bottom surface, and the surface of the graphene sheet described in paragraph 8 is covered with clusters of fine particles made of an insulating metal oxide. Method.

That is, first, a graphene sheet is formed on the bottom surface of the container in the shape of the bottom surface by the manufacturing method described in paragraph 8. Next, a metal compound from which an insulating metal oxide is deposited by thermal decomposition is dispersed in methanol, and the methanol dispersion is filled in the container having a graphene sheet formed on the bottom surface of the container. Note that the metal compound is dispersed in methanol to form a liquid phase. After that, when vibration acceleration in three directions is repeatedly applied to the container, the surface of the graphene sheet on the bottom surface of the container comes into contact with the methanol dispersion. In addition, as explained in paragraph 11, since the graphene sheet exists in the container, a vibration acceleration of about 0.4 G is applied. Furthermore, the container is heated to a temperature at which the metal compound is thermally decomposed. First, the methanol is vaporized, and a cluster of fine crystals of the metal compound precipitates all at once at the portion of the graphene sheet that comes into contact with the methanol dispersion. That is, since the metal compound is dispersed in methanol in a molecular state in the methanol dispersion of the metal compound, when the methanol is vaporized from the methanol dispersion, fine crystals of the metal compound precipitate all at once. After that, the fine crystals of the metal compound are thermally decomposed, and a group of insulating metal oxide fine particles is precipitated all at once on the portion of the graphene sheet that comes into contact with the methanol dispersion, that is, on the entire surface of the graphene sheet. The entire surface of the graphene sheet is covered with fine particles of metal oxide. As a result, the surface of the graphene sheet has insulating metal oxide properties. When the amount of the metal compound dispersed in methanol increases, the number of metal oxide fine particles that precipitate increases, and as a result, the number of metal oxide fine particles that precipitate on the surface of the graphene sheet increases, and the metal oxide fine particles stack together. Then, the entire surface of the graphene sheet is covered with a collection of stacked metal oxide particles.
Among metal oxides, magnetite Fe ₃ O ₄ (a type of iron oxide, also called triiron tetroxide) exists as a conductive metal oxide, and the presence of impurities or from the stoichiometric composition Examples of metal oxides whose insulating properties are lowered by containing a shift component include metal oxides such as chromium oxide CrO ₂ , nickel oxide NiO, zinc oxide ZnO, tin oxide SnO ₂ and copper oxide CuO. All of the insulating metal oxides other than these metal oxides have a high degree. For example, the Mohs hardness is 9 for aluminum oxide Al ₂ O ₃ , 8-8.5 for chromium oxide Cr ₂ O ₃ , and 7-7.5 for titanium oxide TiO ₂ (rutile type). On the other hand, the Mohs hardness of soft metals with excellent thermal conductivity and electrical conductivity is 2.5 for silver, 2.5-3 for copper, 2.5-3 for gold, and 2 for aluminum. Lower altitude than insulating metal oxides. The volume resistivity is 10 ^14-15 Ω·cm for aluminum oxide Al ₂ O ₃ , 10 ⁷ Ω·cm for titanium oxide TiO ₂ , and 10 ¹² Ω·cm for chromium oxide Cr ₂ O ₃ . highly sexual. It should be noted that metal oxides that contain impurities or components that deviate from the stoichiometric composition deteriorate the insulating properties. The above three kinds of highly insulating metal oxides do not contain substances deviating from the stoichiometric composition and do not contain impurities, and are highly insulating metal oxides.

The method of covering the surface of the graphene sheet described in paragraph 16 with a collection of fine particles made of an insulating metal oxide,
Oxygen ions constituting the carboxyl group of the carboxylic acid become ligands, and the carboxylic acid metal compound coordinately bonded to the metal ion is converted into a metal compound in which an insulating metal oxide is deposited by thermal decomposition described in paragraph 16. and covering the surface of the graphene sheet with a collection of fine particles composed of an insulating metal oxide according to the method described in paragraph 16.

That is, the metal carboxylate compound coordinate-bonded to the metal ion with the oxygen ion forming the carboxyl group of the carboxylic acid as a ligand precipitates the metal oxide by thermal decomposition. Therefore, in the method of covering the surface of the graphene sheet described in paragraph 16 with a collection of fine particles of insulating metal oxide, the metal carboxylate described above is used as the metal compound that deposits the insulating metal oxide by thermal decomposition. When the compound is used to cover the surface of the graphene sheet with a collection of insulating metal oxide microparticles according to the method described in paragraph 16, the surface of the graphene sheet becomes electrically insulating. As for the thermal decomposition temperature of the carboxylate metal compound, the temperature at which the naphthenate metal compound thermally decomposes at 330° C. is the highest. In addition, since the thermal decomposition of the carboxylic acid metal compound in the atmospheric atmosphere is 30 to 50° C. lower than the thermal decomposition in the nitrogen atmosphere, the thermal decomposition in the atmospheric atmosphere requires less heat treatment costs. Also, the carboxylic acid metal compound is dispersed in methanol to nearly 10% by weight.
In other words, the oxygen ions that make up the carboxyl group become ligands, and the metal carboxylate compounds approach and coordinate with the metal ions. , the distance between them becomes shorter. Therefore, the oxygen ion coordinatively bonded to the metal ion has the longest distance to the ion covalently bonded on the opposite side of the metal ion. A metal carboxylate compound with such molecular structural features is capable of covalently bonding with an ion on the opposite side of the metal ion, where the oxygen ion that constitutes the carboxyl group exceeds the boiling point of the carboxylic acid that constitutes the metal carboxylate compound. The part is first cleaved and decomposes into metal oxides and carboxylic acids, which are compounds of metal ions and oxygen ions. When the temperature is further increased, the carboxylic acid takes the heat of vaporization and vaporizes, and the metal oxide precipitates immediately after the vaporization of the carboxylic acid is completed. Such metal carboxylate compounds include metal acetate compounds, metal caprylate oxides, metal benzoate oxides, metal naphthenate oxides, and the like.
Some metal oxides of acetate deposit amorphous metal oxides or unstable metal oxides by thermal decomposition. Carboxylic acid metal oxides such as acid metal oxides, benzoic acid metal oxides, and naphthenic acid metal oxides are desirable.
In addition, carboxylic acid metal compounds are inexpensive industrial chemicals that can be easily synthesized. That is, when a general-purpose carboxylic acid is reacted with a strong alkali, an alkali metal carboxylic acid compound is produced. Thereafter, the alkali metal carboxylate compound is reacted with the inorganic metal compound to synthesize the metal carboxylate compound. Moreover, the carboxylic acid used as a raw material is an organic acid having a relatively low boiling point among the boiling points of organic acids, and a metal oxide is precipitated at a heat treatment temperature as low as about 330° C. in an air atmosphere.
As described above, the method of covering the surface of the graphene sheet described in the 16th paragraph with a collection of fine particles of an insulating metal oxide is a metal from which the insulating metal oxide described in the 16th paragraph is deposited by thermal decomposition. As the compound, a carboxylic acid metal compound in which an oxygen ion constituting a carboxyl group of a carboxylic acid is used as a ligand and coordinately bonded to a metal ion is used, and the surface of the graphene sheet is made insulating according to the method described in paragraph 16. is a method of covering with a collection of fine particles made of metal oxide.

The method of removing the graphene sheet described in paragraph 16 from the container comprises:
According to the method described in paragraph 16, a graphene sheet whose surface is covered with a collection of fine particles made of an insulating metal oxide is formed on the bottom surface of a container in the shape of the bottom surface, and a plane above the graphene sheet is formed. Frictional heat is generated at a portion where the metal oxide fine particles are in contact with each other in the collection of the metal oxide fine particles formed on the surface layers of both planes of the graphene sheet. The fine particles of the metal oxide are bonded to each other by frictional heat.
Thereafter, the method for removing the graphene sheet from the container according to paragraph 16, wherein the container is subjected to vibration acceleration in three directions, i.e., back and forth, left and right, and up and down, and the graphene sheet is removed from the container.

That is, when the surface of the graphene sheet produced by the method described in paragraph 16 is covered with a group of insulating metal oxide fine particles, the group of metal oxide fine particles in an active state without impurities is graphene Precipitate on the surface of the sheet. The fine particles of the metal oxide are precipitated by contacting each other, but since the fine particles of the metal oxide are not metallically bonded to each other, the bonding force between the fine particles of the metal oxide is small. Therefore, when the graphene sheet produced by the method described in paragraph 16 is taken out of the container, the fine particles of the metal oxide are easily dissociated from the graphene sheet.
On the other hand, insulating metal oxides have high hardness as described in the 17th paragraph. It also has high compressive strength. For example, the compressive strength of alumina is 3200 MPa, which is 16 times the tensile strength of copper. Therefore, when the upper plane of the graphene sheet formed on the bottom surface of the container is evenly compressed, the metal oxide fine particles formed on the surface layers of both planes of the graphene sheet are neither deformed nor destroyed. Frictional heat is generated at the sites where the fine particles contact each other without reducing the compressive stress. This frictional heat causes the fine particles of the metal oxide to join together. As a result, both flat surfaces of the graphene sheet are covered with a collection of metal oxide microparticles bonded by frictional heat. After that, a vibration acceleration of about 0.2 G is applied to the container in the three directions of back and forth, left and right, and up and down, and the graphene sheet is taken out from the container.
Since the metal oxide fine particles formed on the side surface of the graphene sheet are in contact with the container, when the upper plane of the graphene sheet is evenly compressed, the metal oxide fine particles dissociate from the side surface of the graphene sheet. As for the metal fine particles formed on the side surfaces, frictional heat is generated at the portion where the metal oxide fine particles are in contact with each other, and the metal oxide fine particles are bonded to each other by the frictional heat. However, since the compressive stress acting on the metal oxide fine particles is not as large as the compressive stress acting on the metal oxide fine particles formed on both planes of the graphene sheet, the bonding force between the metal oxide fine particles is It is smaller than the bonding force between the metal oxide fine particles formed on both planes of the graphene sheet.
In this graphene sheet, the metal oxide fine particles on the surface layer are bonded to each other by frictional heat, and the aggregation of the metal oxide fine particles has a certain bonding force. This makes it possible to handle the graphene sheet taken out of the container.
Both planes of the graphene sheet are formed with a collection of metal oxide fine particles bonded by frictional heat, so the graphene sheet can be pressure-bonded to a base material or a component. That is, when a graphene sheet is placed on the surface of a part or a base material, and the flat surfaces of the graphene sheet are evenly compressed, the fine metal oxide particles on one surface of the graphene sheet bite into the surface of the part or the base material. As a result, the graphene sheet is crimped to the component or base material, and the other plane of the crimped graphene sheet has insulating properties. As a result, the graphene sheet, which has excellent thermal and electrical conductivity and an insulating surface, is crimped onto the component or base material.

FIG. 2 is an explanatory view schematically showing an enlarged part of a side surface of a graphene sheet in which flat planes of graphene overlap with each other;

Example 1
This example is an example in which a graphene sheet composed of a group of graphenes in which the flat surfaces of the graphenes are overlapped and bonded is formed on the bottom surface of the container according to the manufacturing method described in the eighth paragraph.
First, 2 liters of methanol were filled into a shallow container with a base of 1.2 m x 1.2 m.
Next, prepare parallel plate electrodes having an effective area of 1 m×1 m, which generates an electric field in the gap between the two parallel plate electrodes. Graphite particles are spread evenly on the surface. Assuming that the graphite particles are spheres with a particle diameter of 25 μm and that the average thickness of the graphite particles is 10 μm, the graphite particles are spread evenly in the 100 μm gap formed by the two parallel plate electrodes. , there are 6.4×10 ⁷ graphite particles. When a DC voltage of 10.6 kilovolts or more is applied to this group of graphite particles, the interlaminar bonds of the basal planes of all the graphite particles are broken at the same time. At this time, a group of 1.9×10 ¹³ graphene particles is obtained, and the group of graphite particles used is only 1.18 g.
For this purpose, 10 g of scale-like graphite particles (eg, XD100 manufactured by Ito Graphite Industry Co., Ltd.) was laid on the surface of a parallel plate electrode having an effective area of 1 m×1 m for generating an electric field. This parallel plate electrode is immersed in a container filled with methanol, the other parallel plate electrode is superimposed on the parallel plate electrode, and the two parallel plate electrodes are separated by a gap of 100 μm, A DC voltage of 12 kilovolts was applied across the electrodes. Next, the gap between the two parallel plate electrodes is widened, the two parallel plate electrodes are tilted in methanol, and a vibration acceleration of 0.2 G in three directions is repeatedly applied to the container. Two parallel plate electrodes were taken out from the . Furthermore, the methanol in the container was subjected to ultrasonic vibration of 20 kHz for 2 minutes using an ultrasonic homogenizer (product LUH300 from Yamato Scientific Co., Ltd.). After this, the container was again repeatedly subjected to a vibration acceleration of 0.2 G in three directions.
The container was then heated to 65° C. to vaporize the methanol. Furthermore, a 1.2 m × 1.2 m aluminum plate is placed on the upper plane of the sample formed on the bottom of the container, and a 20 kg weight is placed on the aluminum plate, and the upper plane of the sample is evenly distributed. Compressed. After removing the weight and the aluminum plate, the container was subjected to a three-way vibration acceleration of 0.2 G and the sample was removed from the container. An aluminum plate was placed again on the removed sample, and a weight of 10 kg was further placed thereon, but the state of the sample did not change.
Next, the two planes and sides of the sample were observed and analyzed using an electron microscope. As an electron microscope, an ultra-low accelerating voltage SEM manufactured by JFE Techno-Research Corporation was used. This device is capable of surface observation with an ultra-low acceleration voltage from 100 V, and has the feature that the surface of a sample can be observed directly without forming a conductive film on the sample. First, a secondary electron beam between 900-1000 volts of the reflected electron beam from the plane of the sample was extracted and imaged. An extremely thin step was confirmed on the plane of the sample. Next, a secondary electron beam between 900 and 1000 volts of the reflected electron beam from the side surface of the sample was picked up and subjected to image processing. There were 10 layers of very thin material on top of each other. Furthermore, as a result of image processing of the energy and intensity of the characteristic X-rays, it was confirmed that only carbon atoms existed, and that the sample was a graphene sheet in which flat planes of graphene overlapped with each other.
FIG. 1 schematically shows an enlarged part of the side surface of the graphene sheet in which flat planes of graphene are overlapped with each other. 1 is graphene.
Even when the graphene sheet was taken out from the container and a weight of 10 kg was placed on the graphene sheet, the graphene sheet was not broken, so the flat surfaces of the graphene were bonded together with a constant bonding force.

Example 2
This example is an example in which the surface of the graphene sheet formed on the bottom surface of the container in Example 1 is covered with aggregates of silver fine particles.
First, a metal compound that deposits silver by thermal decomposition is dispersed in methanol to prepare a methanol dispersion. As a silver compound, two ammines, which is one of the silver complex ions that are most easily synthesized, are chlorides of diammine silver ion [Ag(NH ₃ ) ₂ ] ⁺¹ coordinated to silver ion Ag ⁺ . Using diammine silver chloride [Ag(NH ₃ ) ₂ ]Cl (for example, a product of Tanaka Kikinzoku Hanbai Co., Ltd.), 0.1 mol of diammine silver chloride was dispersed in 100 cc of methanol. This methanol dispersion was filled in the container in Example 1, in which the graphene sheet was formed on the bottom surface of the container in the shape of the bottom surface. A three-way vibrational acceleration of 0.4 G was then repeatedly applied to the container. Further, the container was heated to 180° C. in a hydrogen gas atmosphere and left at 180° C. for 5 minutes. After that, the container was again subjected to vibration acceleration of 0.4 G in three directions for a short time, and the sample was taken out from the bottom of the container.
Next, two planes and side surfaces of the sample were observed and analyzed with the electron microscope used in Example 1. First, a secondary electron beam between 900 and 1000 V of the reflected electron beam was picked up and subjected to image processing. Granular particles with a size of 40 to 60 nm were evenly formed on both the plane surface and the side surface. Next, the energy between 900 and 1000 V of the reflected electron beam was extracted and image processing was performed, and the difference in material was observed according to the density of the image. Since no shading was observed, they were formed from the same material. Furthermore, the energy and intensity of the characteristic X-rays were image-processed, and the elements constituting the fine particles were analyzed. It was found that only silver atoms were present, and the granular fine particles were silver fine particles.
Next, the cluster of silver fine particles formed on the side surface of the sample was peeled off, and the secondary electron beam between 900 and 1000 V of the reflected electron beam from the side surface of the sample was taken out to perform image processing. As with the side surface of Example 1, a graphene sheet in which flat planes of graphene overlapped was observed. From this result, it was found that the surface of the graphene sheet was covered with clusters of silver fine particles.
As described above, in Example 1, a graphene sheet in which the flat surfaces of graphene are bonded together is formed on the bottom surface of the container, and in Example 2, a collection of silver fine particles is precipitated on the surface of the graphene sheet, and graphene The surface of the sheet was covered with fine silver particles. After this, the container was briefly subjected to vibration acceleration in three directions of 0.4 G, and the sample was removed from the bottom of the container. At this time, since the silver fine particles were not separated from the graphene sheet, it was found that the cluster of silver fine particles covered the graphene sheet with a certain strength. Therefore, the graphene sheet can be handled, and when the graphene sheet is placed on a base material or part and compressed, the graphene sheet is crimped to the base material or part via the silver fine particles, and the crimped graphene sheet is , showing the thermal conductivity of graphene and the conductivity of silver.

Example 3
This example is an example in which the surface of the graphene sheet formed on the bottom surface of the container in Example 1 is covered with aggregates of fine particles of aluminum oxide Al ₂ O ₃ . Aluminum oxide is an insulator having a volume resistivity of 10 ^14-15 Ω·cm and a dielectric strength of 10-15 kV/mm.
First, 0.1 mol of aluminum benzoate Al(C ₆ H ₅ COO) ₃ (eg, a product of Mitsuwa Chemicals Co., Ltd.) was dispersed in 100 cc of methanol to prepare a methanol dispersion. This methanol dispersion was filled in the container in Example 1, in which the graphene sheet was formed on the bottom surface of the container in the shape of the bottom surface.
A three-way vibrational acceleration of 0.4 G was then repeatedly applied to the container. Further, the container was heated to 310° C. in the atmosphere and left at 310° C. for 1 minute. After that, similarly to Example 1, an aluminum plate was placed on the upper plane of the sample in the container, and a weight of 10 kg was further placed thereon, after which the weight and the aluminum plate were taken out. Furthermore, a vibration acceleration of 0.2 G in three directions was applied to the container for a short time, and the sample was removed from the container. A weight of 5 kg was placed on the removed sample again, but the fine particles were not peeled off from the surface of the sample.
After that, as in Example 2, observation and analysis of two planes and sides of the sample were performed with an electron microscope. Granular fine particles having a size of 40 to 60 nm were evenly stacked on both the plane surface and the side surface, and the granular fine particles were composed of aluminum oxide.
After that, all the clusters of granular fine particles on the side surface were peeled off, and the side surface was observed again with an electron microscope. As a result, as in the case of the side surface of Example 1, a graphene sheet in which flat planes of graphene overlapped with each other was observed.
From this result, it was found that the surface of the graphene sheet was covered with a collection of fine particles of aluminum oxide. Further, even when the graphene sheet was taken out from the container and a weight of 5 kg was placed on the graphene sheet, the aluminum oxide fine particles were not dissociated from the graphene sheet. are joined by frictional heat, and the surface of the graphene sheet is covered with a certain amount of strength by a collection of fine particles of aluminum oxide.
From the above results, in Example 1, a graphene sheet in which the flat surfaces of graphene were bonded was formed on the bottom surface of the container, and in Example 3, a collection of fine particles of aluminum oxide was deposited on the surface of the graphene sheet, and graphene The surface of the sheet was covered with a mass of fine particles of aluminum oxide. After that, when compressive stress was evenly applied to the entire planar surface of the graphene sheet, the fine particles of aluminum oxide bonded to each other by frictional heat at the portions where they were in contact with each other. For this reason, the graphene sheet can be handled, and when the graphene sheet is placed on a base material or part and compressed, the graphene sheet is crimped to the base material or part via fine particles of aluminum oxide, and is crimped. The graphene sheet has the thermal conductivity of graphene, and the surface exhibits insulating properties.

1 graphene

Claims (7)

A method for producing a graphene sheet consisting of a collection of graphene in which the flat planes of graphene overlap and are joined,
A collection of scale-like graphite particles or a collection of massive graphite particles is evenly spread on the surface of one of the two parallel-plate electrodes, and the parallel-plate electrode is immersed in methanol filled in a container. Further, the other parallel plate electrode is superimposed on the one parallel plate electrode, and the two parallel plate electrodes are separated via the collection of the scale-like graphite particles or the collection of the massive graphite particles. , the two spaced apart parallel plate electrodes are immersed in the methanol;
After that, a DC potential difference is applied across the gap between the two parallel plate electrodes, whereby an electric field corresponding to the value obtained by dividing the potential difference by the gap between the two parallel plate electrodes is generated. , a coulomb sufficient to break the interlayer bonding of the basal planes of graphite crystals for all of the graphite particles by the application of the electric field applied to the cluster of flake graphite particles or the cluster of massive graphite particles. A force is simultaneously applied to all the π electrons responsible for the interlaminar bonds of the basal planes forming the graphite particles, thereby causing all the interlaminar bonds of the basal planes forming the flake graphite particles or the massive graphite particles. are destroyed at the same time, and a group of graphene corresponding to the basal plane is produced in the gap between the two parallel plate electrodes.
After that, the gap between the two parallel plate electrodes is widened, the two parallel plate electrodes are tilted in the methanol, and further vibration acceleration is repeatedly applied to the container in three directions, left and right, front and back, and up and down. , transferring the graphene mass from the gap between the two parallel plate electrodes into the methanol, after which the two parallel plate electrodes are removed from the container;
Furthermore, the homogenizer device is operated in methanol in the container, and the collection of graphene is repeatedly impacted through the methanol, and the collection of graphene is separated into individual graphenes in the methanol. After that, remove the homogenizer device from the container,
Further, vibrational acceleration in three directions of front and back, left and right, and up and down is repeatedly applied to the container, and a collection of the graphene in which the flat surfaces of the graphene are overlapped with methanol is formed on the bottom surface of the container as the shape of the bottom surface. do,
After that, the container is heated to the boiling point of the methanol to vaporize the methanol, and a collection of the graphene in which the flat surfaces of the graphene overlap each other is formed on the bottom surface of the container as the shape of the bottom surface.
After that, the upper plane of the graphene aggregate is evenly compressed to generate frictional heat at the portion where the flat surfaces of the graphene overlap each other, and the flat surfaces of the graphene are bonded to each other by the frictional heat, and the graphene A graphene sheet consisting of a collection of graphenes in which the flat surfaces of graphene are overlapped and bonded is formed on the bottom surface of the container in the shape of the bottom surface, and a graphene consisting of a collection of graphenes in which the flat surfaces of graphene are overlapped and bonded A method of manufacturing a sheet. The method of covering the surface of the graphene sheet according to claim 1 with a collection of fine metal particles made of any metal of silver, copper, gold, or aluminum,
A metal compound in which any metal of silver, copper, gold, or aluminum precipitates by thermal decomposition is dispersed in methanol to prepare a methanol dispersion, and the methanol dispersion is added to the container in which the graphene sheet according to claim 1 is placed. The container formed on the bottom surface of the graphene sheet is filled with the graphene sheet, and the container is repeatedly subjected to vibration acceleration in three directions: left and right, front and back, and up and down, so that the surface of the graphene sheet is brought into contact with the methanol dispersion.
After that, the container is heated to a temperature at which the metal compound is thermally decomposed, whereby the methanol is first vaporized, and a collection of fine crystals of the metal compound precipitates all at once on the surface of the graphene sheet. After that, the fine crystals of the metal compound are thermally decomposed, and on the surface of the graphene sheet, a collection of granular metal fine particles made of any metal of silver, copper, gold, or aluminum precipitates all at once, The granular metal fine particles are metallically bonded at the sites where they contact each other, and the surface of the graphene sheet is covered with a collection of metal fine particles made of any metal of silver, copper, gold, or aluminum that is metallically bonded. A method of covering the surface of the graphene sheet according to claim 1 with a collection of fine metal particles made of any one of silver, copper, gold, and aluminum. The method of covering the surface of the graphene sheet according to claim 2 with a collection of fine metal particles made of any metal of silver, copper, gold, or aluminum,
A metal complex composed of an inorganic metal compound having a metal complex ion in which a ligand composed of an inorganic ion or an inorganic molecule is coordinated to a metal ion composed of a metal of silver, copper, gold, or aluminum, Any metal of silver, copper, gold, or aluminum described in claim 2 is used as a metal compound that is deposited by thermal decomposition, and according to the method described in claim 2, the surface of the graphene sheet is treated with silver, copper, or gold. , or aluminum. The method of covering the surface of the graphene sheet according to claim 2 with a collection of fine metal particles made of any metal of silver, copper, gold, or aluminum,
The first feature is that the oxygen ion that constitutes the carboxyl group of the carboxylic acid is covalently bonded to a metal ion made of a metal such as silver, copper, gold, or aluminum, and the second feature is that the carboxylic acid is a saturated fatty acid. A carboxylic acid metal compound having the above characteristics is used as a metal compound from which any metal of silver, copper, gold, or aluminum described in claim 2 is deposited by thermal decomposition, and according to the method described in claim 2, A method of covering the surface of a graphene sheet with a collection of fine metal particles made of silver, copper, gold, or aluminum. The method of covering the surface of the graphene sheet according to claim 1 with a collection of fine particles made of an insulating metal oxide,
A metal compound in which an insulating metal oxide is deposited by thermal decomposition is dispersed in methanol to prepare a methanol dispersion. The container is filled, and the container is repeatedly subjected to vibration acceleration in three directions: left and right, front and back, and up and down, so that the surface of the graphene sheet is brought into contact with the methanol dispersion.
After that, the container is heated to a temperature at which the metal compound is thermally decomposed, whereby the methanol is first vaporized, and a collection of fine crystals of the metal compound precipitates all at once on the surface of the graphene sheet. After that, the fine crystals of the metal compound are thermally decomposed, and a collection of fine particles of the insulating metal oxide is precipitated on the surface of the graphene sheet all at once, and the fine particles of the insulating metal oxide are deposited on the surface of the graphene sheet. 2. The surface of the graphene sheet according to claim 1, wherein the graphene sheet whose surface is covered with aggregates is formed on the bottom surface of the container in the shape of the bottom surface, wherein the surface of the graphene sheet is formed with aggregates of fine particles made of an insulating metal oxide. how to cover. The method of covering the surface of the graphene sheet according to claim 5 with a collection of fine particles made of an insulating metal oxide comprises:
The oxygen ion constituting the carboxyl group of the carboxylic acid becomes a ligand, and the carboxylic acid metal compound coordinately bonded to the metal ion is converted to the metal from which an insulating metal oxide is deposited by thermal decomposition as described in claim 5. A method of covering the surface of a graphene sheet with a collection of fine particles composed of an insulating metal oxide, according to the method of claim 5, using the compound as a compound. The method for removing the graphene sheet according to claim 5 from the container comprises:
According to the method of claim 5, a graphene sheet whose surface is covered with a collection of fine particles made of an insulating metal oxide is formed on the bottom surface of the container in the shape of the bottom surface, and a plane above the graphene sheet is formed. Frictional heat is generated at the site where the metal oxide fine particles are in contact with each other in the collection of metal oxide fine particles formed on the surface layers of both planes of the graphene sheet, The frictional heat causes the fine particles of the metal oxide to join together.
6. The method for taking out a graphene sheet from a container according to claim 5, wherein thereafter, vibration acceleration in three directions of back and forth, left and right, and up and down is applied to the container to take out the graphene sheet from the container.

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