Method for preparing thermally conductive sheet having insulating surface covered with collection of insulating and thermally conductive powder on graphene joint made by joining superposed graphenes to each other by frictional press bonding

Abstract

To provide a thermally conductive material having an insulating surface by a new manufacturing method using a new material without using a conventional technique for compositing or mixing a material having thermal conductivity with a non-thermally conductive material.SOLUTION: A collection of graphite particles is laid in a gap between two parallel plate electrode pairs, the electrode pairs are immersed in methanol, a potential difference is given to the electrode gap, the interlayer bonding of base surfaces of graphite crystals consisting of graphite particles are simultaneously disrupted, and the collection of graphenes is deposited in methanol. Vibrational acceleration in three directions is applied to the collection of graphenes dispersed in methanol, and the graphenes are superimposed with faces thereof oriented upward. The entire surface of the collection of superimposed graphenes is compressed evenly to form a graphene joint 2. The graphene joint is covered with a suspension in which the collection of insulating and thermally conductive powders are dispersed in alcohol. After vaporizing the alcohol, the entire surface of the graphene joint is compressed evenly to prepare a thermally conductive sheet in which the graphene joint is covered with the collection of frictionally press bonded powders.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] In the present invention, graphene conjugates are stacked face up and the entire surfaces of the stacked graphene conjugates are uniformly compressed. Next, the fabricated graphene conjugates are covered with a suspension in which insulating and thermally conductive powder conjugates are dispersed in alcohol. After the alcohol is evaporated, the entire surfaces of the graphene conjugates are uniformly compressed, and the powder conjugates in contact with the surface of the graphene conjugates are friction-welded to the surface of the graphene conjugates, and the powder conjugates are friction-welded to each other at the contact points, so that the graphene conjugates are covered with the friction-welded powder conjugates. It has excellent thermal conductivity and insulation properties, is thin and lightweight, and has mechanical strength. It has to do with how the sheet is created. According to the present invention, the thickness of the graphene composite is submicron and the thickness of the friction-welded powder aggregate is only a few particles, so the weight of the thermally conductive sheet is two orders of magnitude less than that of conventional thermally conductive sheets. Furthermore, because the powder is micron-sized and many of the powder particles are connected in parallel, the insulation resistance of the thermally conductive sheet is two orders of magnitude greater than that of conventional thermally conductive sheets. Furthermore, because the graphene composite, which has better thermal conductivity than metals, is covered with fine thermally conductive powder, the thermal conductivity of the thermally conductive sheet is superior to that of conventional thermally conductive sheets. The present inventors have already filed a patent application, JP 2019-090295 (filed on May 12, 2019), for a method for producing a graphene conjugate in which flat surfaces of graphene are bonded together with an assembly of metal fine particles made of any one of silver, copper, gold, and aluminum. The present invention relates to a method for producing a graphene conjugate in which flat surfaces of graphene are bonded together with an assembly of insulating and thermally conductive powder. It has excellent thermal conductivity and insulation properties, is thin and lightweight, and has mechanical strength. How to create a sheet. [Background technology]

[0002] In recent years, advances in electronics technology have led to advances in the miniaturization, weight reduction, density, and output of electronic devices. As a result, there is a strong demand for improvements in the reliability of insulation associated with the increased density of electronic circuits, as well as improvements in heat dissipation properties that are useful for preventing thermal degradation of electronic devices due to heat generation from electronic devices and high-density packaging. On the other hand, in the electronics field, many insulating materials are made of polymeric materials, which have poor thermal conductivity. Therefore, to improve the thermal conductivity of polymeric materials, a method is used in which solid thermally conductive particles are filled into the polymeric material as thermal conductors. In this method, a collection of thermally conductive particles forms a thermal conduction path within the polymeric material, achieving excellent thermal conductivity. However, for the thermally conductive particles to form a thermal conduction path within the polymeric material, a high filling rate of the thermally conductive particles is required. However, the rate at which the thermally conductive particles can be filled into the molten polymeric material is limited by the increase in viscosity. As a result, the conventional method of filling solid thermally conductive particles into a polymeric material has a limit to how much the thermal conductivity of the polymeric material can be improved.

[0003] There are various techniques for imparting thermal conductivity. For example, Patent Document 1 describes a technology for manufacturing an aggregate in which insulating and thermally conductive spherical particles such as aluminum oxide or aluminum nitride are aggregated with an organic binder. In other words, the aggregate in which thermally conductive particles are aggregated together via an organic binder is used as the carrier of thermal conductivity. Patent Document 2 also describes a manufacturing technology for an elastomer material that combines thermal conductivity, vibration damping, and cushioning properties. Specifically, vibration damping and cushioning properties are ensured by adding a softener in an amount 3-10 times the weight of the thermoplastic elastomer, and pitch-based carbon fibers are used to provide thermal conductivity, filling the molded body with 10-40% by volume of pitch-based carbon fibers, thereby ensuring thermal conductivity without sacrificing vibration damping and cushioning properties. Furthermore, Patent Document 3 describes a technology for producing a resin composition in which one of two resins, a polyphenylene sulfide resin and a polyamide resin, has an island structure and the other has a sea-like structure, forming a three-dimensional network structure, and a thermal conductivity imparting agent is unevenly distributed in the sea-like structure resin, thereby improving thermal conductivity without reducing mechanical strength or moldability. In other words, by filling the sea-like structure resin with a thermal conductivity imparting agent, the thermal conductivity of the sea-like structure resin is increased, and heat is conducted along the sea-like structure, thereby improving the thermal conductivity of the resin composition. Patent Document 4 also describes a manufacturing technology for a thermosetting resin molding material that is excellent in mechanical strength, heat resistance, dimensional accuracy, and thin-wall formability without reducing electrical insulation, and that is also thermally conductive. That is, by filling the first filler with needle-shaped wollastonite having a Mohs hardness of 4.5-5.0, tensile strength and bending strength are ensured, and the thermal expansion coefficient of wollastonite is 6.5×10 -6 / °C, ensuring dimensional stability and thin-wall formability. Furthermore, the high melting point of wollastonite at 1540°C provides heat resistance. In addition, the use of spherical particles of insulating and thermally conductive alumina as the second filler improves thermal conductivity without reducing the electrical insulation of the thermosetting resin.

[0004] However, the technology described in Patent Document 1 has two problems when it comes to improving thermal conductivity. First, an organic binder is dissolved in a solvent, and a cluster of thermally conductive particles is dispersed in the dissolved organic binder to create a slurry. The solvent is then evaporated to create a substance called a deformable aggregate. The thermal conductivity of this deformable aggregate depends heavily on the proximity of the thermally conductive particles to each other, because only the thermally conductive particles are responsible for thermal conduction. To achieve this, the ratio of thermally conductive particles to the organic binder must be significantly increased. However, as the ratio of thermally conductive particles increases, the ratio of organic binder in the deformable aggregate decreases, making it difficult to bind the spherical thermally conductive particles via the organic binder. Second, the deformable aggregate is mixed with a binder resin with poor thermal conductivity, and the mixture is compressed to produce a thermosetting sheet. Because a thermally conductive sheet cannot be produced using only deformable aggregates, a thermally conductive sheet can be produced by combining the deformable aggregates with a binder resin, and then compressing the combined deformable aggregates. However, because binder resins are non-thermally conductive, the thermal conductivity of the deformable aggregates cannot be reflected in the thermally conductive sheet unless the binder resin mixing ratio is reduced. On the other hand, the lower the binder resin mixing ratio, the more difficult it becomes to bond the deformable aggregates together, making it impossible to produce a thermally conductive sheet. Furthermore, the technology described in Patent Document 1 requires multiple separate manufacturing processes to produce thermally conductive sheets, resulting in high manufacturing costs. Furthermore, the thermally conductive particles used as raw materials are expensive spherical fine particles, and the amount used is not small. While it would be sufficient to achieve high added value, such as thermal conductivity comparable to that of metals and insulation, the thermal conductivity achieved by this technology is at least one order of magnitude lower than that of metals, limiting the product fields to which this technology can be applied.

[0005] Furthermore, in the technology described in Patent Document 2, the thermal conductivity of the elastomer material increases in accordance with the volume fraction of pitch-based carbon fiber. However, even when the volume fraction of the very expensive pitch-based carbon fiber is increased to 50%, the thermal conductivity is only 8.21 W / (m·K), which is low considering the extremely high manufacturing cost. This is because the thermal conductivity of pitch-based carbon fiber is anisotropic, and although it has a high thermal conductivity of 500 W / (m·K) in the fiber axis direction, it is difficult to orient pitch-based carbon fiber in the fiber axis direction and fill it into an elastomer material. Furthermore, pitch-based carbon fiber has a volume resistivity of 2×10 -5 The elastomer material has electrical conductivity consisting of 1000 vol. cm, and the higher the filling rate of pitch-based carbon fiber, the more conductive the elastomer material becomes. Therefore, if the elastomer material is to be combined with other components while maintaining its electrical insulation, an electrically insulating and non-thermally conductive adhesive must be used, and the thermal conductivity of the elastomer material is impaired by the non-thermally conductive adhesive layer. Furthermore, the higher the volume fraction of pitch-based carbon fiber, the harder the elastomer material becomes, and the lower its vibration-damping and shock-absorbing properties become. Therefore, the product fields to which this technology can be applied are limited.

[0006] Furthermore, the technology described in Patent Document 3 produces resin molded bodies through three manufacturing processes: preparing a first masterbatch by mixing a special compatibilizer with a polyphenylene sulfide resin; preparing a second masterbatch by mixing a surface-modified thermal conductivity agent with a polyamide resin; and melt-kneading the first and second masterbatches. Therefore, this technology produces resin molded bodies through three separate processes. Furthermore, because it requires a complex process for preparing the special compatibilizer in advance and a process for modifying the surface of the thermal conductivity agent in advance, the manufacturing costs for resin molded bodies are high. On the other hand, even when filled with thermally conductive particles at a weight ratio of 60%, the thermal conductivity of the resin molded bodies is low at 1-2 W / (m·K). This is because the ratio of thermally conductive particles, which are thermal conductivity imparting agents, filled as fillers into the ocean-like resin is limited by the increased viscosity of the resin when dissolved, making it difficult to bring the fillers closer together. Furthermore, if the thermally conductive particles are electrically conductive, the higher the filling ratio of the thermally conductive particles in the ocean-like resin, the greater the electrical conductivity of the ocean-like resin. Because of the ocean-like structure of the resin, the electrical conductivity of the resin molded body increases. Therefore, if the resin molded body is to be combined with other components while maintaining electrical insulation, an electrically insulating and non-thermally conductive adhesive must be used, and the thermal conductivity of the resin molded body will be impaired by the non-thermally conductive adhesive layer. Therefore, the product fields to which this technology can be applied are limited.

[0007] Furthermore, the technology described in Patent Document 4 is notable for its use of acicular wollastonite particles as a first filler, but its use of alumina particles as a second filler is no different from conventional techniques for filling resin with alumina particles as a conductive filler. Therefore, the alumina particle filling ratio is limited to 80% by weight due to the increase in viscosity of the thermosetting resin when it is dissolved. Even if the alumina particles are filled at 80% by weight, it is difficult to bring the alumina particles close to each other in the thermosetting resin, so the thermal conductivity of the resulting thermosetting resin molding is only about 1 W / (m·K). Therefore, the product fields to which this technology can be applied are also limited.

[0008] Here, the problems associated with the conventional techniques for imparting thermal conductivity will be summarized. If the materials responsible for thermal conductivity can be made into a continuous or adjacent structure, the thermal conduction path will be thermally conductive. Sheet On the other hand, in the conventional technology, a non-thermally conductive material is always interposed between materials that are responsible for thermal conductivity, which creates resistance that hinders thermal conduction and inhibits the improvement of thermal conductivity. Sheet The problem is that the insulating material responsible for thermal conductivity has a continuous or adjacent structure. Therefore, this problem cannot be solved by the conventional technology of combining or mixing the insulating material responsible for thermal conductivity with a non-thermal conductive material. The second issue is the dispersibility of the material responsible for thermal conductivity. In other words, the greater the volume occupancy of the material responsible for thermal conductivity, the greater the thermal conductivity. Sheet The probability that the materials responsible for thermal conductivity will come into contact or be close to each other increases within the material, making it easier for the materials responsible for thermal conductivity to form a continuous or close structure. As a result, the thermal conductivity Sheet However, if the material responsible for thermal conductivity is solid, the thermal conductivity Sheet There is a limit to the proportion of thermally conductive particles that can be dispersed within the polymer material. That is, as explained in the prior art, the higher the filling rate of the thermally conductive particles, the higher the viscosity of the molten polymer material, making it impossible to perform molding processes such as extrusion or injection of the molten polymer material. Furthermore, as explained in the problem points of Patent Document 2, it is difficult to disperse pitch-based carbon fibers in a molten polymer material while orienting them in the fiber axis direction. Furthermore, it is also difficult to disperse the acicular particles in Patent Document 4 while orienting them in the acicular direction. For this reason, the prior art of compounding or mixing a solid thermally conductive substance with a non-thermally conductive substance cannot solve the problem of dispersibility of the thermally conductive substance. The third issue is the aggregation of the material responsible for thermal conductivity. That is, Patent Documents 1, 3, and 4 describe a technique for filling a molten polymer material with thermally conductive particles, but the finer the particles are and the more symmetrical the particles are, the more likely they are to aggregate. When particle aggregation occurs, the thermal conductivity is reduced. Sheet Therefore, the conventional technique of filling a molten polymer material with fine particles or spherical particles cannot solve the problem of agglomeration of the material responsible for thermal conductivity. The fourth issue is thermal conductivity. Sheet The properties of SiO2 are that it has thermal conductivity close to that of metal and excellent insulation. These properties are particularly important for products used in the electronics field. Sheet Even if a material is given thermal conductivity close to that of metal, if it is conductive, it is necessary to ensure electrical insulation, and in many cases, an inexpensive adhesive that is electrically insulating and non-thermally conductive is used, but the non-thermally conductive adhesive layer makes it impossible to bond thermally conductive materials together. Note that the higher the insulating and thermally conductive properties, the higher the thermal conductivity. Sheet The added value of the above-mentioned conventional technology is high. Sheet has low added value because its thermal conductivity is at least one order of magnitude lower than that of metals. The fifth challenge is to develop a low-cost manufacturing method. 、 Insulation in Thermal conductivity Sheet In particular, products used in the electronics field tend to use inexpensive components or inexpensive substrates. Therefore, as in the above-mentioned conventional techniques, if the manufacturing method involves multiple separate steps, a manufacturing method using very expensive raw materials, or a manufacturing method requiring pre-treatment of the raw materials, the manufacturing costs will rise and the method is not suitable for manufacturing inexpensive industrial products. The sixth issue is insulation. in Thermal conductivity Sheet However, the key point is that it can be easily assembled to other parts or substrates. 、 Insulation in Thermal conductivity Sheet Even if it can be created, if it cannot be easily assembled to other parts or substrates, Sheet The added value of The seventh issue is insulation in Thermal conductivity Sheet However, they are lightweight and thin. In particular, products in the electronics field are becoming smaller, lighter, and thinner, which means that the weight is increasing and the added value of the parts or substrates that take up the thickness is low. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-03261 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-63716 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-263476 [Patent Document 4] Japanese Patent Application Laid-Open No. 2009-221308 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0010] The above Sheet Many of the above problems arise when a solid material that provides thermal conductivity is compounded or mixed with a non-thermal conductive material, such as a molten polymer material. Therefore, as long as a manufacturing method is used in which a solid material that provides thermal conductivity is compounded or mixed with a non-thermal conductive material, these problems cannot be solved. Sheet Based on a completely new idea that dispels the concept of manufacturing methods, we use new materials and new manufacturing methods. 、 Insulation in Thermal conductivity Sheet These problems cannot be solved unless an insulating material based on a completely new concept is created. in Thermal conductivity Sheet There is a strong demand for technology to create The problem to be solved by the present invention is: A thin, lightweight sheet with excellent thermal conductivity and insulation properties, and mechanical strengthIn creating this product, new materials were used and a new manufacturing method was used based on a completely new idea that simultaneously solves the seven problems described in paragraph 8. A thin, lightweight sheet with excellent thermal conductivity and insulation properties, and mechanical strength. The goal is to realize the technology to create [Means for solving the problem]

[0011] The graphene joint, which is made by friction welding stacked graphene sheets, is covered with a collection of insulating and thermally conductive powder. It has excellent thermal conductivity and insulation properties, is thin and lightweight, and has mechanical strength. How to create a sheet: Two parallel plate electrodes board One of the parallel plate electrodes consists of board A group of flake graphite particles or a group of lump graphite particles is spread evenly on the surface of one of the parallel plate electrodes. board The other parallel plate electrode is immersed in methanol filled in a first container, and the other parallel plate electrode is placed on the one parallel plate electrode via the clusters of flake graphite particles or the clusters of lump graphite particles. board The two parallel plate electrodes are placed on top of each other. board a pair of electrodes consisting of the above-mentioned graphite particles and the above-mentioned lump graphite particles is immersed in the methanol, thereafter a direct current potential difference of a predetermined magnitude is applied to the gap between the pair of electrodes, thereby applying an electric field corresponding to the value obtained by dividing the magnitude of the potential difference by the size of the gap between the pair of electrodes to the collection of flake graphite particles or the collection of lump graphite particles, and by applying the electric field, all of the interlayer bonds of the basal planes of the graphite crystals that form the flake graphite particles or the lump graphite particles are simultaneously destroyed, and a collection of graphene consisting of the basal planes is precipitated in the gap between the pair of electrodes, thereafter the gap between the pair of electrodes is enlarged, the pair of electrodes is tilted in the methanol, and furthermore, vibration accelerations are repeatedly applied to the first container in three directions, left and right, front and back, and up and down, in order, to move the collection of graphene from the gap between the pair of electrodes into the methanol, thereafter the two parallel plate electrodes are removed from the first container, board a first step of extracting the graphene from the first container and preparing a collection of graphene dispersed in methanol in the first container; a second step of operating an ultrasonic homogenizer device in the first container, repeatedly applying shock waves to the graphene aggregates through the methanol, and separating the graphene aggregates into individual graphene sheets in the methanol, and then removing the homogenizer device from the first container, and creating a suspension in the first container consisting of the graphene aggregates separated into individual graphene sheets in the methanol; a predetermined weight of the suspension is poured into a second container, vibration accelerations are applied to the second container in three directions, i.e., forward / backward, left / right, and up / down, in order, and finally a vibration acceleration in the up / down direction is applied, so that the graphene clusters in the suspension are randomly arranged in the suspension with their faces facing up; a first flat plate having the same size as the inside size of the second container is placed over the suspension in the second container so as to be in contact with the suspension; the second container is heated to the boiling point of the methanol to evaporate the methanol from the suspension; and the graphene clusters are stacked with their faces facing up; and then the entire surface of the first flat plate is uniformly compressed. As a result, the stacked graphene aggregates with the surface facing up are compressed, the stacked graphene aggregates are friction-welded together, and a graphene aggregate made up of the friction-welded graphene aggregate is formed on the bottom surface of the second container in the shape of the bottom surface of the second container; thereafter, impact acceleration is simultaneously applied to a plurality of locations on the bottom surface of the second container to peel the graphene aggregate from the bottom surface of the second container; and further, impact acceleration smaller than the above impact acceleration is simultaneously applied to a plurality of locations on a side surface of the first flat plate to peel the graphene aggregate from the first flat plate, thereby removing the graphene aggregate; Alcohol with a viscosity of 4-6 mPa·sec at 20°C for the weight of Weight of a mass of insulating and thermally conductive powder of ratio rate a fourth step of weighing the alcohol and the powder mass in a predetermined weight ratio where the weight ratio is less than 1, pouring the weighed alcohol and powder into a third container, and stirring the alcohol in the third container to create a new suspension in which the powder mass is dispersed in the alcohol; a fifth step of immersing the removed graphene conjugate in the new suspension to cause the new suspension to adhere to the graphene conjugate, and then removing the graphene conjugate from the new suspension; The aforementioned New suspension adhered The graphene conjugate is placed on the second flat plate so that the entire surface of the graphene conjugate overlaps the second flat plate, and then a third flat plate having the same size as the second flat plate is placed over the entire surface of the graphene conjugate. The temperature is then raised to the boiling point of the alcohol to evaporate the alcohol from the new suspension attached to the graphene conjugate, and the entire surface of the graphene conjugate is covered with the powder. Thereafter, the entire surface of the third flat plate is uniformly compressed, thereby compressing the powder in contact with the surface of the graphene conjugate. a sixth step of friction-welding a collection of powder particles to a surface of the graphene conjugate and friction-welding the powder particles to each other at locations where the powder particles contact each other, so that the graphene conjugate is covered with the friction-welded collection of powder particles; thereafter, applying impact acceleration simultaneously to a plurality of locations on a side surface of the second flat plate to peel the graphene conjugate from the second flat plate; and further applying impact acceleration equivalent to the impact acceleration simultaneously to a plurality of locations on a side surface of the third flat plate to peel the graphene conjugate from the third flat plate, so that the graphene conjugate is removed; By carrying out these six steps in succession, the stacked graphene sheets were friction-welded together to form a graphene joint, which was then covered with an assemblage of insulating and thermally conductive powder. It has excellent thermal conductivity and insulation properties, is thin and lightweight, and has mechanical strength. The sheet is created Excellent thermal conductivity and insulation, thin and lightweight, and mechanically strong How to create a sheet.

[0012] The present invention consists of the following six extremely simple steps. The first step is to prepare a suspension of graphene particles dispersed in methanol in a container. board A collection of flake graphite particles or a collection of lump graphite particles spread in the gap between two parallel plate electrodes is immersed in an insulating medium, methanol. Board A direct current potential difference of a predetermined magnitude is applied between the two parallel plate electrodes. board The electric field corresponding to the value divided by the size of the gap between the electrodes where a collection of flake graphite particles or a collection of lump graphite particles exists is Board This electric field simultaneously applies a Coulomb force sufficient to destroy the interlayer bonds of the basal planes of all the graphite particles to all the π electrons that are responsible for the interlayer bonds of the basal planes, which are made up of graphite crystals. As a result, the π electrons are released from the constraints on the π orbitals, and all the π electrons move away from the π orbitals and become free electrons. In other words, when the Coulomb force acting on the π electrons is applied to the π electrons as a force greater than the interaction of the π orbitals, the π electrons are released from the constraints of the π orbitals and become free electrons. As a result, all the π electrons that are responsible for the interlayer bonds of the basal planes no longer exist on the π orbitals, and all the interlayer bonds of the basal planes of the graphite crystals that form the graphite particles are simultaneously destroyed for all the graphite particles. This causes the two parallel plate electrodes board A collection of basal planes, that is, a collection of graphene, is instantly created in the gap between the two parallel plate electrodes. The created graphene is a genuine material without impurities, consisting only of graphite crystals. board Since the electrode is immersed in methanol, two parallel plate electrodes board The graphene aggregates deposited in the gaps do not scatter. That is, two parallel plate electrodes immersed in an insulating solution of methanol Board When a potential difference is applied between the two parallel plate electrodes board An electric field is generated in the gap. Methanol is an insulator with a specific resistance of 3 MΩ·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 has an electrical conductivity of 1.7 x 10 compared to flake graphite particles, which are conductive. 7 It is a twice weaker insulator. The graphite particles are made from natural graphite crystals as a mineral, and there are three types of refined graphite particles: flake graphite particles, lump graphite particles (also called scaly graphite particles), and amorphous graphite particles. The amorphous graphite particles have poorer crystallinity than the other two types of graphite particles, and therefore the amount of graphene obtained by breaking the interlayer bonds of the amorphous graphite particles is smaller than that of the other two types of graphite particles. Furthermore, the flake graphite particles are flatter particles with a larger aspect ratio than the lump graphite particles. Therefore, breaking the interlayer bonds of the flake graphite particles results in graphene with a larger aspect ratio than the lump graphite particles. On the other hand, the lump graphite particles are larger than the flake graphite particles. Therefore, breaking the interlayer bonds of the lump graphite particles results in more graphene than the flake graphite particles. For this reason, flake graphite particles or lump graphite particles were used as the graphite particles. Next, the graphene assembly is placed between two parallel plate electrodes. board The two parallel plate electrodes are connected to each other. board The gap between the graphene particles is expanded in methanol, and then tilted in methanol. After this, the container filled with methanol is subjected to three repeated vibration accelerations of 0.2-0.3G depending on the size of the container. This causes the graphene particles to move between the two parallel plate electrodes. board The gas then moves through the gap between the two parallel plate electrodes into the methanol. board The resulting solution is a suspension of graphene aggregates dispersed in methanol. The second step is to create a suspension in a container consisting of graphene aggregates separated into individual sheets in methanol. For this purpose, a homogenizer is operated in the suspension in which the graphene aggregates are dispersed in methanol. In other words, shock waves are repeatedly applied to the graphene aggregates via methanol. This separates the graphene aggregates into individual graphene sheets in the methanol, and the separated graphene aggregates are dispersed in the methanol. In other words, when an ultrasonic homogenizer is operated in the suspension, the generation and disappearance of a huge number of extremely fine bubbles, which are more than one order of magnitude smaller than the flat surface of graphene, occur in accordance with the period of the ultrasonic vibration frequency. methanol This phenomenon is called cavitation, and the shock waves generated by the bursting of the bubbles are repeatedly applied to the clusters of graphene, which have almost no mass, causing the clusters of graphene to separate into individual graphene sheets in a short period of time in the methanol. As a result, the clusters of graphene separated into individual graphene sheets are dispersed in the methanol. That is, the shock waves applied to the low-viscosity, low-density methanol by the homogenizer device are consumed only to a small extent by the molecular vibration of the methanol, and many of the shock waves are applied to the clusters of graphene, which have almost no mass. Since the bonding force between overlapping graphene sheets is extremely small, when shock waves are applied to the overlapping graphene sheets, the overlapping of the graphene sheets is released in the methanol in a short period of time and reliably, and the clusters of graphene are separated into individual graphene sheets. As a result, the clusters of graphene, in which the graphene sheets separated into individual graphene sheets are covered with methanol, are dispersed in the methanol. Medium The resulting suspension is dispersed in The third step involves forming the graphene conjugate on the bottom surface of a second container in the shape of the bottom surface, peeling the graphene conjugate from the bottom surface of the second container, and then peeling the graphene conjugate from the first flat plate to remove the graphene conjugate. To achieve this, a predetermined weight of the suspension is poured into the second container. Depending on the size of the container, vibration accelerations of 0.3-0.4 G are applied to the second container in three directions (front-back, left-right, and up-down) in sequence, and finally, a vibration acceleration of 0.3-0.4 G is applied to the second container in the up-down direction, randomly aligning the graphene clusters face-up in methanol. In other words, when vibration acceleration is applied to graphene that has been covered with methanol and separated into individual graphene sheets in methanol, the graphene, which has almost no mass, moves in the vibration direction. However, because graphene is extremely thin (0.332 nm), its aspect ratio, which is the ratio of its area to its thickness, is extremely large. Therefore, when graphene is subjected to vibrational acceleration in methanol, it is least stressed when it moves through the methanol with its face up. Therefore, when a collection of graphene is repeatedly subjected to vibrational acceleration in three directions, the individual graphene sheets are stacked in a random arrangement with their faces up in the methanol. Finally, vibrational acceleration in the vertical direction is applied, ensuring that the individual graphene sheets are stacked in a random arrangement with their faces up in the methanol. Then, a first flat plate having the same size as the inside of the second container is placed over the suspension in the second container. The second container is then heated to the boiling point of methanol, evaporating the methanol from the suspension. This causes the graphene to overlap with itself, face up. The entire surface of the first flat plate is then uniformly compressed. This compresses the overlapping graphene particles, causing friction welding between the overlapping graphene particles. A graphene conjugate consisting of the friction-welded graphene particles is then formed on the bottom surface of the second container in the shape of the bottom surface. An impact acceleration of 0.6-0.8 G, depending on the size of the container, is then simultaneously applied to multiple locations on the bottom surface of the second container, thereby peeling the graphene conjugate from the bottom surface of the second container. Furthermore, an impact acceleration smaller than the above-mentioned impact acceleration is simultaneously applied to multiple locations on the side surface of the first flat plate, peeling the graphene conjugate from the first flat plate, and then the graphene conjugate is removed. In other words, when methanol evaporates from the graphene aggregate, the aggregate of graphene randomly arranged face up becomes an aggregate of graphene overlapping face up. When this aggregate of graphene is uniformly compressed as a whole, all the graphene overlaps each other face up, so the graphene directly friction-welds to each other at the overlapping surfaces, and the aggregate of friction-welded graphene becomes a thin graphene conjugate, which is formed on the bottom surface of the second container in the shape of the bottom surface. When the graphene conjugate was produced, compressive stress was applied in a direction perpendicular to the bottom surface of the second container, so the bonding force between the graphene conjugate and the second container has a certain magnitude. On the other hand, the weight of the graphene conjugate is significantly greater than the weight of the second container. light Therefore, when impact acceleration is applied simultaneously to multiple points on the bottom surface of the second container, the impact force is equal to the impact acceleration multiplied by the mass, and therefore the impact force received by the graphene conjugate is significantly smaller than the impact force received by the second container. Therefore, when impact acceleration of 0.6-0.8 G, depending on the size of the container, is applied simultaneously to multiple points on the bottom surface of the second container, the bonded portion between the graphene conjugate and the bottom surface of the second container peels off first, and the graphene conjugate peels off from the bottom surface of the second container. In addition, the weight of the first flat plate is much heavier than the weight of the second container. lightHowever, it is significantly lighter than the weight of the graphene junction. heavy For this reason, when an impact acceleration smaller than the impact acceleration applied to the bottom surface of the second container is simultaneously applied to multiple locations on the side surface of the first flat plate, the bonded portion between the graphene conjugate and the bottom surface of the first flat plate is preferentially peeled off, and the graphene conjugate is peeled off from the bottom surface of the first flat plate. The fourth step is to prepare a new suspension by dispersing the insulating and thermally conductive powder in alcohol with a viscosity of 4-6 mPa·sec at 20°C. against Weight of powder mass of ratio rate The alcohol and powder mass are weighed out in a predetermined weight ratio of less than 1, the weighed alcohol and powder are poured into a third container, and the alcohol is stirred to create a new suspension in which the powder mass is dispersed in the alcohol. The fifth step is to apply a new suspension to the graphene conjugate to a thickness depending on the viscosity of the new suspension. To do this, the graphene conjugate is immersed in the new suspension and then removed. Note that because the viscosity of alcohol is relatively low at 4-6 mPa·sec, the thickness of the suspension applied to the graphene conjugate is only a few microns. The sixth step is to cover the surface of the graphene joint with a friction-welded powder mass. S This is the process of creating a chart. New suspension adhered The entire surface of the graphene junction is placed on the second plate. New suspension adhered The graphene conjugate is placed on top of the second flat plate. Furthermore, a third flat plate of the same size as the second flat plate is placed over the entire surface of the graphene conjugate. After this, the temperature is raised to the boiling point of the alcohol, and the alcohol is evaporated from the new suspension attached to the graphene conjugate. As a result, a powder mass covers the entire surface of the graphene conjugate with a thickness according to the viscosity of the new suspension. Furthermore, the entire surface of the third flat plate is evenly compressed. As a result, the powder mass in contact with the surface of the graphene conjugate is friction-welded to the surface of the graphene conjugate, and the powder particles are friction-welded to each other at the locations where they contact each other, so that the graphene conjugate is covered with the friction-welded powder mass. SAfter this, an impact acceleration of 0.4-0.6G is applied simultaneously to multiple points on the side of the second flat plate, depending on the size of the plate. S and peeling the third flat plate from the sheet, and then simultaneously applying an impact acceleration equal to the impact acceleration to a plurality of points on the side surface of the third flat plate. S The sheet is peeled off the third plate. S Remove the card. That is, the weight of the second plate or the third plate is light However, it is significantly lighter than the weight of the graphene junction. heavy Therefore, when an impact acceleration smaller than the impact acceleration applied to the bottom surface of the second container is simultaneously applied to multiple locations on the side surface of the second flat plate or the third flat plate, the bonded portion between the graphene conjugate and the bottom surface of the second flat plate or the bottom surface of the third flat plate will peel off first, and the graphene conjugate will peel off from the bottom surface of the second flat plate or the bottom surface of the third flat plate. Therefore, compared to the weight of the second container, the weight of the second flat plate or the third flat plate is light Therefore, an impact acceleration of 0.4 to 0.6 G, which is smaller than the impact acceleration applied in the third step, is simultaneously applied to multiple locations on the side surface of the second flat plate or the third flat plate, and the graphene conjugate is peeled off from the second flat plate or the third flat plate. Furthermore, when a graphene composite covered with a powder mass is compressed, the thickness of the graphene composite is one order of magnitude smaller than the size of the powder. Therefore, when the powder attached to the edges of the front and back surfaces of the graphene composite is compressed, the powder protrudes from the edges of the graphene composite and the protruding powder particles are friction-welded together. As a result, the edges of the front and back surfaces of the graphene composite are also insulated by the friction-welded powder. By carrying out these six steps in succession, the graphene joint, in which stacked graphene aggregates were joined by friction welding, was covered with an aggregate of insulating and thermally conductive powder. It has excellent thermal conductivity and insulation properties, is thin and lightweight, and has mechanical strength. The sheet is created.

[0013] Created using the method described above S The effects of the port will be explained. First, the surface of the sheet is covered with a collection of insulating and thermally conductive powder, and based on the insulating and thermally conductive properties of the powder, S For example, if the friction-welded powder has a volume resistivity of 10 14 If the powder has a diameter of 1 μm and a volume resistivity of Ω·cm, the resistance of the powder is calculated by multiplying the volume resistivity by 2 / (π·radius), which is 0.64×10 4 multiplied by 0.64 × 10 18 On the other hand, S When a potential difference is applied to the sheet, the potential difference is applied in a direction parallel to the sheet surface. In this case, the insulating powder bonded to the surface of the graphene composite acts as a resistor. The resistance value formed by this group of resistors consists of the following three types. First, a group of powders connected in the plane direction of the sheet has powder resistors connected in series, forming a resistance value equal to the number of series-connected powders. Second, a small number of powders stacked in a direction perpendicular to the sheet surface have powder resistors connected in parallel, forming a resistance value equal to the small number of parallel-connected powders. Third, when parallel-connected powders are bonded adjacent to each other in the plane direction of the sheet, an even greater number of parallel-connected powders are connected in parallel, forming a resistance value equal to the group of parallel-connected powders. The group of powders forms a resistance value that is the sum of these three types of resistance values. On the other hand, the third resistance value is overwhelmingly larger than the first and second resistance values, so a single resistor has a resistance of 0.64 × 10 18 Ω, the insulation resistance of the powder mass is 10 18 The conductivity of the graphene composite is well above Ω. STo ensure the insulation of the surface of the sheet, it is not necessary to stack a large number of insulating powders; simply stacking a few insulating powders by friction welding can achieve extremely high insulation resistance. Furthermore, because graphene is extremely thin at 0.332 nm and has an extremely large aspect ratio, its conductivity in the thickness direction is extremely low, while electrons preferentially move in the plane direction, resulting in high conductivity in the plane direction. Incidentally, graphene's volume resistivity is 1.3 μΩcm, even lower than the 1.6 μΩcm of silver, which has the lowest volume resistivity of any metal. Second, graphene conjugates with a certain area constitute the interior of the sheet, while a collection of powder particles covering the surface of the graphene conjugate constitutes the exterior of the sheet. Since the thickness of the stacked powder particles is only a few particles, the properties of the sheet reflect the properties of the graphene conjugate. Furthermore, since all graphene particles are stacked face-up and directly friction-welded to each other, the graphene conjugate is composed of a collection of friction-welded graphene particles, so the graphene conjugate has properties similar to those of graphene. On the other hand, because graphene is extremely thin at 0.332 nm and has an extremely large aspect ratio, its thermal conductivity in the thickness direction is extremely low, and heat is preferentially transferred in the plane direction. The thermal conductivity of graphene is 1880 W / (m·K), which is 4.5 times that of silver, the metal with the highest thermal conductivity. Therefore, a graphene conjugate in which all graphene particles are joined face-to-face has thermal conductivity similar to that of graphene. Therefore, the sheet can be used for a 10 18 It has an extremely high insulation resistance, well above Ω, and thermal conductivity close to that of graphene. S In conventional sheets, the material responsible for thermal conductivity is electrically conductive, so high insulation resistance and high thermal conductivity are contradictory properties. However, the sheet of the present invention possesses both of these properties, overturning conventional wisdom. Third, when all the graphene layers are stacked face-up and friction-welded, high-temperature friction heat is generated on the overlapping graphene surfaces for a short period of time. Graphene has heat resistance exceeding 3000°C. This instantly vaporizes impurities present on the overlapping graphene surfaces, purifying them. Because the purified graphene surfaces are friction-welded together, the bonding strength between the graphene layers is high. Furthermore, the overlapping graphene surfaces only have a 0.332 nm step, equivalent to the thickness of the graphene. This allows for a flatter surface than a mirror finish to be friction-welded, resulting in a strong friction weld between the surfaces. Furthermore, graphene is a highly durable material with a breaking strength of 42 N / m, more than 100 times that of steel, and a Young's modulus of 1020 GPa. Therefore, when the overlapping graphene layers are friction-welded together, they do not break. In contrast, with the exception of some metal nitride powders, powders that combine insulation and thermal conductivity have a Mohs hardness of 8 or higher. Therefore, the powders do not easily break down when compressive stress is applied, and relatively large compressive stress can be applied to friction-weld the powders together. For this reason, when a relatively large compressive stress is applied to a group of powders, high-temperature frictional heat is generated at the contact points where the powders come into contact with each other, causing impurities present at the contact points to instantly vaporize, resulting in friction-welding at the cleaned contact points. Furthermore, frictional heat is generated at the contact points of the powders in contact with graphene, causing impurities present at the contact points to instantly vaporize, resulting in friction-welding to the graphene at the cleaned contact points. Graphene is harder than diamond, with a Mohs hardness of 10. Therefore, even if excessive compressive stress is applied to the powder mass in the sixth step, causing the powder to fracture, the graphene in contact with the powder will not be destroyed. On the other hand, if excessive compressive stress is applied to the powder to fracture it, the crushed powder will move to fill the voids in the powder mass, causing the crushed powder mass to overlap at high density. Furthermore, as the powder is crushed, the number of contact points between the powder particles increases. When the powder reaches its limit of fracture, excessive compressive stress is applied directly to the crushed powder, generating high-temperature frictional heat at the contact points where the crushed powder particles come into contact with each other, causing the powder particles to frictionally weld together at the contact points. Furthermore, when the crushed powder mass in contact with the graphene comes into contact with the graphene, high-temperature frictional heat is generated at the contact points where the crushed powder particles come into contact with the graphene, causing the powder particles to frictionally weld to the graphene at the contact points. At this time, high-temperature frictional heat corresponding to the excessive compressive stress is generated at the contact points between the crushed powder particles and at the portions where the crushed powder particles contact graphene. As a result, impurities present at the contact points between the crushed powder particles and at the portions where the crushed powder particles contact graphene are instantaneously vaporized, and the contact points between the crushed powder particles and at the portions where the crushed powder particles contact graphene are purified. Because the contact points of the purified powder particles and the portions where the purified powder particles contact the purified graphene are friction-welded, the number of contact points between the crushed powder particles increases, and excessive compressive stress caused by pushing the powder particles to their limit is applied to the contact points, so the bonding strength between the highly crushed powder particles and the bonding strength between the highly crushed powder particles and graphene become the greatest. On the other hand, if excessive compressive stress is applied to the graphene conjugate covered with powder aggregates, the bonding force between the flat plate overlaid on the graphene conjugate covered with powder aggregates and the friction-welded graphene conjugate covered with powder also increases. Therefore, when peeling the flat plate and the thermally conductive sheet apart, a larger impact acceleration needs to be applied to the flat plate. Fourth, the thickness of the graphene junction is submicron, while the thickness of the powder particles piled up is several microns. S The weight of the cart is SThe weight of the powder is lighter than that of graphene by more than two orders of magnitude. On the other hand, when the powders are friction-welded together and when the powders are friction-welded to the surface of a graphene joint, the powders have high hardness and do not easily break, so a relatively large compressive stress can be applied to the powders. When a relatively large compressive stress is applied to a collection of powders, frictional heat of a temperature corresponding to the compressive stress is generated at the contact point where the powders come into contact with each other, and impurities present at the contact point are instantaneously vaporized, and the friction-welded occurs at the cleaned contact point. In addition, high-temperature frictional heat is also generated at the contact point of the powders in contact with graphene, and impurities present at the contact point are instantaneously vaporized, and the friction-welded to graphene at the cleaned contact point. Because the contact point between the powders, which have a small weight, is cleaned and the cleaned contact point is friction-welded at a high temperature, and because the contact point between the powders, which have a small weight, and graphene is cleaned and the cleaned contact point is friction-welded at a high temperature, the friction-welded joint strength is large. For this reason, the present invention S The route is S It has greater mechanical strength than conventional S The route is Sheet Weight reduction and Sheet However, the sheet of the present invention possesses both of these properties, which defies conventional wisdom. Fifth, the sheet has excellent heat resistance, does not react with acids or alkalis, and does not change over time for a long period of time. That is, graphene is a single crystal material with a melting point exceeding 3000°C, and its heat resistance temperature exceeds 3000°C. It is also an extremely stable substance that does not react with acids or alkalis. Therefore, a graphene joint formed by friction welding a group of graphene also has heat resistance close to that of graphene, and does not react with acids or alkalis. Furthermore, since the insulating and thermally conductive powder is composed of metal oxides or metal nitrides, it has a heat resistance temperature of 900°C or higher and, except for some metal nitride powders, does not react with acids or alkalis. For this reason, S The grease has excellent heat resistance, does not react with acids or alkalis, and does not change over time even in outdoor environments for a long period of time. Sixth, the sheet can be made by carrying out six extremely simple steps in succession. In addition, graphite particles and powder are general-purpose industrial materials, and alcohol is a general-purpose organic solvent. solventTherefore, the conventional S Compared to cellulose, it has excellent properties at a very low cost. S You can create a route. As explained above, the sheet of the present invention is based on a new concept that is completely different from conventional sheets in terms of material composition and manufacturing method, and therefore provides groundbreaking effects, thereby resolving the seven problems described in paragraph 8.

[0014] As stated in paragraph 11 S To create a route, The insulating and thermally conductive powder described in paragraph 11 is alumina, nitrogen It is either one kind of powder made of silicon dioxide or aluminum nitride, Either one of the following The powder is used as the insulating and thermally conductive powder described in paragraph 11, and the powder is used as the insulating and thermally conductive powder described in paragraph 11. S Create a sheet according to the method described in paragraph 11. S How to create a route.

[0015] That is, alumina, nitrogen Powders made of silicon dioxide or aluminum nitride have high thermal conductivity and high volume resistivity among insulating powders. Alumina has a thermal conductivity of 33-41 W / (m·K) depending on its purity, and a volume resistivity of 10 14-15 Ω·cm. nitrogen Silicon dioxide has a thermal conductivity of 20-28 W / (m·K), depending on the manufacturing method, and a volume resistivity of 10 14 Ω·cm. Aluminum nitride has a thermal conductivity of 170 W / (m·K) and a volume resistivity of 10 14 These metal oxides and nitrides have excellent thermal conductivities among insulators, but are significantly smaller than the thermal conductivity of graphene, which is 1880 W / (m K). Therefore, a graphene junction with a certain area S The inside of the shell is made up of a group of powder particles that are overlapping and bonded together. S By configuring the surface of the SThe properties of the graphene junction are reflected in the surface, giving it thermal conductivity close to that of metal. In addition, the volume resistivity is 10 14 If a powder with a resistivity of Ω·cm is treated as a disk with a diameter of 1 μm, the resistance is 2 / volume resistivity. ( π radius ) The volume resistivity is multiplied by 0.64×10 4 On the other hand, S When a potential difference is applied to the port, the potential difference is S A voltage is applied in a direction parallel to the surface of the sheet. In this case, the insulating powder bonded to the surface of the graphene composite acts as a resistor, and as described in paragraph 13, the resistance value formed by the group of resistors consists of the following three types. First, a group of powders connected in the plane direction of the sheet has resistors made of powder connected in series, forming a resistance value equal to the number of series-connected powders. Second, a small number of powders stacked in a direction perpendicular to the plane of the sheet have resistors made of powder connected in parallel, forming a resistance value equal to the small number of parallel-connected powders. Third, when parallel-connected powders are bonded adjacent to each other in the plane direction of the sheet, an even greater number of parallel-connected powders are connected in parallel, forming a resistance value equal to the group of parallel-connected powders. The group of powders forms a resistance value that is the sum of these three types of resistance. On the other hand, the third resistance value is overwhelmingly larger than the first and second resistance values, so that a single resistor has a resistance of 0.64 × 10 18 Ω, the insulation resistance of the powder mass is 10 18 Easily exceeds Omega. Furthermore, the Mohs hardness of alumina is 8-9, which is high. Ku , nitrogen Silicon nitride has a high Mohs hardness of 8.3-9, while aluminum nitride has a high Mohs hardness of 9-10. Therefore, in the sixth step described in paragraph 11, when compressing the powder mass, powderThe powder does not easily break down. Therefore, high-temperature frictional heat is generated at the contact points between the powder particles and where the powder contacts the graphene, causing the powder particles to be friction-welded to each other and to the surface of the graphene. On the other hand, the Mohs hardness of graphene is greater than that of diamond, which is 10. Furthermore, the Young's modulus of alumina is 330 GPa, that of silicon nitride is 310 GPa, and that of aluminum nitride is 320 GPa. In comparison, the Young's modulus of graphene is an extremely large 1020 GPa. Furthermore, the breaking strength of graphene is an extremely large 42 N / m. Therefore, when compressing the powder mass in the sixth step described in paragraph 11, excessive compressive stress is applied, pushing the powder to its limit. Size The graphene composite does not break even if it is crushed to the point where it is broken. On the other hand, when the powder is crushed by applying excessive compressive stress, the crushed powder moves and fills the voids in the powder cluster. As a result, the crushed powder clusters overlap at high density and the contact area between the crushed powder clusters increases. When the powder reaches its limit of crushing, excessive compressive stress is directly applied to the crushed powder, and frictional heat of a temperature corresponding to the excessive compressive stress is generated for a short period of time at the contact areas between the crushed powder clusters and at the locations where the crushed powder clusters contact the graphene composite. As a result, impurities present at the contact areas between the crushed powder clusters and at the locations where the crushed powder clusters contact the graphene composite are instantaneously vaporized and purified. Because the purified contact areas are friction-welded and the compressive stress applied to the contact areas during friction welding is the largest, the bonding force between the crushed powder clusters and the bonding force between the crushed powder clusters and the graphene composite are the largest. On the other hand, if excessive compressive stress is applied to the graphene conjugate covered with powder aggregates, the bonding force between the flat plate overlaid on the graphene conjugate covered with powder aggregates and the friction-welded graphene conjugate covered with powder also increases. Therefore, when peeling the flat plate and the thermally conductive sheet apart, a larger impact acceleration needs to be applied to the flat plate. In addition, the heat resistance temperature of alumina in the atmosphere is 1500°C. nitrogenThe heat resistance temperature of silicon dioxide in an air atmosphere is 1200°C, and that of aluminum nitride is 900°C, both of which have high heat resistance temperatures. Furthermore, all powders except aluminum nitride do not react with acids or alkalis. Aluminum nitride reacts with water containing alkalis and decomposes into alumina and ammonia. Therefore, all powders except aluminum nitride do not react with acids or alkalis and do not change over time even in outdoor environments for long periods of time. As explained above, the insulating and thermally conductive powder described in paragraph 11 includes alumina, nitrogen By using either one of the powders consisting of silicon dioxide or aluminum nitride, the sheet has a revolutionary effect, as described in paragraph 13.

[0016] As stated in paragraph 11 S To create a route, The alcohol having a viscosity of 4-6 mPa·s at 20°C described in paragraph 11 is any one of 2-pentanol, 3-methyl-1-butanol, tert-amyl alcohol, 2-butanol, 2-methyl-1-butanol, 2-heptanol, isobutyl alcohol, 4-methyl-2-pentanol, 3-pentanol, and 2-octanol, Either one of the following The alcohol is used as the alcohol described in paragraph 11, and the alcohol described in paragraph 11 S Follow the steps to create a route S The method according to claim 1 S How to create a route.

[0017] In other words, alcohols consisting of 2-pentanol, 3-methyl-1-butanol, tert-amyl alcohol, 2-butanol, 2-methyl-1-butanol, 2-heptanol, isobutyl alcohol, 4-methyl-2-pentanol, 3-pentanol, and 2-octanol have a viscosity of 4-6 mPa·s at 20°C. Furthermore, the alcohol with the highest boiling point among these alcohols is 2-octanol, with a boiling point of 178°C. Therefore, the temperature required to vaporize the alcohol in the sixth step in paragraph 11 is at most 178°C, making the heat treatment in the sixth step easy. That is, 2-pentanol is an alcohol with a viscosity of 3.5 mPa·s at 20°C, a boiling point of 119°C, and the rational formula is CH3(CH2)CH(OH)CH3. 3-Methyl-1-butanol is an alcohol with a viscosity of 3.7 mPa·s at 20°C, a boiling point of 131°C, and the rational formula is (CH3)2CH(CH2)2OH. Tertiary amyl alcohol has a viscosity of 3.8 mPa·s at 25°C, a boiling point of 103°C, and the rational formula is CH3CH2COH(CH3)2. 2-butanol is an alcohol with a viscosity of 3.9 mPa·s at 20°C, a boiling point of 99°C, and the rational formula is CH3CH2CH(OH)CH3. 2-Methyl-1-butanol is an alcohol with a viscosity of 4.0 mPa·s at 20°C, a boiling point of 108°C, and the rational formula is CH3CH2CH(CH3)CH2OH. 2-Heptanol is an alcohol with a viscosity of 4.0 mPa·s at 20°C, a boiling point of 159°C, and the rational formula is CH3(CH2)4CH(OH)CH3. Isobutyl alcohol is an alcohol with a viscosity of 4.0 mPa·s at 20°C, a boiling point of 108°C, and the rational formula is (CH3)2CHCH2OH. 4-Methyl-2-pentanol is an alcohol with a viscosity of 4.1 mPa·s at 20°C, a boiling point of 132°C, and the rational formula is (CH3)2CHCH2CHOHCH3. 3-Pentanol is an alcohol with a viscosity of 6.4 mPa·s at 20°C, a boiling point of 116°C, and the rational formula is CH3CH2CH(OH)CH2CH3. 2-Octanol is an alcohol with a viscosity of 6.2 mPa·s at 20°C, a boiling point of 178°C, and the rational formula is CH3(CH2)5CH(OH)CH3. These alcohols are all general-purpose organic solvents This makes the processing in the fourth step in paragraph 11 inexpensive. Furthermore, because the viscosity of alcohol is relatively low at 4-6 mPa·sec, the insulating and thermally conductive powder described in paragraph 15 disperses well in alcohol simply by stirring it. Furthermore, in the fifth step in paragraph 11, when a graphene conjugate is immersed in a suspension of powder dispersed in alcohol and then removed, the suspension adheres to the entire surface of the graphene conjugate with a thickness depending on the viscosity of the suspension. Furthermore, in the sixth step of paragraph 11, a flat plate of the same size as the graphene conjugate is placed over the graphene conjugate, and the graphene conjugate covered with the flat plate is heated to the boiling point of the alcohol to evaporate the alcohol, so that the entire surface of the graphene conjugate is covered with a powder aggregate. After this, the entire surface of the flat plate is uniformly compressed. As a result, the powder aggregate in contact with the surface of the graphene conjugate is friction-welded to the surface of the graphene conjugate, and the powder aggregates are friction-welded to each other at the locations where they contact each other, so that the graphene conjugate is covered with the friction-welded powder aggregate. S A route is created.

[0018] Created using the method described in paragraph 11 S The method of integrating the gate into the component or substrate is as follows: According to the method described in paragraph 11 S Create a route and Sheet A part or a substrate is placed on the surface of the part or the substrate, and the entire surface of the part or the substrate is uniformly coated. etc. By this, a collection of insulating and thermally conductive powders covering the surface of the sheet are frictionally welded to the surface of the part or the base material; Applicable Sheet and Applicable Parts or Applicable The substrate is integrated with the method described in paragraph 11. S A method of integrating a part into a component or substrate.

[0019] In other words, the surface of the sheet prepared by the method described in paragraph 11 is covered with an aggregate of insulating and thermally conductive powder, which then serves as a means for friction welding the sheet to a component or substrate. That is, S A part or a substrate is placed on the surface of the sheet, and the entire surface of the part or the substrate is uniformly etc. First, S The insulating and thermally conductive powder mass covering the surface of the sheet comes into contact with the surface of the part or base material, frictional heat is generated at the contact point, and the insulating and thermally conductive powder mass and the contact point with the surface of the part or base material are friction-welded. S The substrate and the component are bonded together via a group of insulating and thermally conductive powder. The insulating and thermally conductive powder is made of metal oxide or metal nitride. Mo It is a hard powder with a hardness of 8 or more. S Apply evenly to the entire surface of the part or substrate placed on the surface of the mat. etc. When compressed to S The insulating and thermally conductive powder particles that cover the surface of the sheet bite into the surface of the part or base material, and high-temperature frictional heat is generated at the contact point between the powder particles and the surface of the part or base material, causing friction welding at the contact point. S The bond strength with the board is high. for example, S Place the printed circuit board on the mat and apply evenly to the entire surface of the printed circuit board. etc. When compressed to S The insulating and thermally conductive powder particles that cover the surface of the board bite into the surface of the printed circuit board, and the powder particles are then frictionally welded to the surface of the printed circuit board. S The card and the printed circuit board are bonded via the powder mass. This allows the heat of the printed circuit board to be efficiently transferred through the powder mass. Stransmitted to the S It is released into the atmosphere from the port. S The board has excellent heat sink properties, so even if many heat-generating elements are mounted on the printed circuit board, the semiconductor elements mounted on the printed circuit board will not be thermally deteriorated. Also, S Place the metal foil on the sheet and apply evenly to the entire surface of the metal foil. etc. When compressed to S The powder particles covering the surface of the sheet bite into the surface of the metal foil, and the powder particles are then frictionally welded to the surface of the metal foil. S The card and the metal foil are bonded together via the powder particles. After this, the metal foil is processed into a printed circuit board on which a conductor pattern is formed. S The powder covering the board is made of metal oxide or metal nitride, and except for aluminum nitride, it is extremely stable chemically, so the powder clusters do not undergo chemical changes. S transmitted to the S Therefore, even if many heat generating elements are mounted on the printed wiring, the semiconductor elements mounted on the printed wiring will not be thermally deteriorated. Examples of the heat generating element include a light emitting diode element, an IC chip made of a wide gap semiconductor, an IGBT chip, or a power MOSFET. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 10 is an enlarged schematic view of a portion of the side surface of a sheet of a graphene composite whose surface is covered with aluminum nitride powder. DETAILED DESCRIPTION OF THE INVENTION

[0021] Example 1 In this example, a suspension consisting of individual graphene sheets separated in methanol is prepared in a container according to the method described in paragraph 11. First, 5 liters of methanol was filled into a shallow container with a base of 2.2 m x 2.2 m. Next, two parallel plate electrodes board The effective area of ​​the electrode in which the electric field is generated is 2m x 2m. board Prepare two parallel plate electrodes. board The graphite particles are assumed to be spheres with a particle size of 25 μm, and the two parallel plate electrodes are placed one on top of the other with a gap of 100 μm between them. board When graphite particles are packed evenly into the 100 μm gap created by 8 When a DC voltage of 10.6 kV or more is applied to this collection of graphite particles, the interlayer bonds on the basal planes of all the graphite particles are simultaneously destroyed. 13 A cluster of graphene particles was obtained, and the cluster of graphite particles used was only 4.72 g. Electrodes that generate an electric field board Parallel plate electrodes with an effective area of ​​2m x 2m board 50 g of flake graphite particles (for example, XD100 manufactured by Ito Graphite Industries Co., Ltd.) were piled up and packed onto the surface of this parallel plate electrode. board The electrode was immersed in a container filled with methanol, and the other parallel plate electrode board The parallel plate electrodes board Two parallel plate electrodes are placed on top of each other. board The electrodes were separated by a gap of 100 μm, and a DC voltage of 12 kV was applied between the electrodes. board The gap between the two parallel plate electrodes is enlarged. board The container is tilted in methanol, and vibration acceleration of 0.2G in three directions is repeatedly applied to the container. After this, two parallel plate electrodes are removed from the container. board The container was then removed. Furthermore, ultrasonic vibrations of 20 kHz were applied to the methanol in the container for 2 minutes using an ultrasonic homogenizer (LUH300, a product of Yamato Scientific Co., Ltd.). After this, the ultrasonic homogenizer was removed from the container. The graphene aggregates dispersed in the methanol in the container were then stirred. Next, a portion of the prepared sample was removed and observed and analyzed using an electron microscope. The electron microscope used was an ultra-low accelerating voltage SEM from JFE Techno-Research Corporation. This device is capable of surface observation at ultra-low accelerating voltages starting from 100 volts, and has the advantage of being able to directly observe the surface of a sample without forming a conductive coating on the sample. Secondary electron beams between 900-1000 volts were extracted from the electron beam reflected from the surface of the sample and image processing was performed. It was confirmed that the material dispersed in methanol was an extremely thin, flat material. Furthermore, image processing of the energy and intensity of the characteristic X-rays revealed that only carbon atoms were present. This confirmed that the material was graphene. This allows two parallel plate electrodes board A collection of flake graphite particles is packed into the gap between the electrodes, and a direct current potential difference is applied between the electrodes. board An electric field equivalent to the value obtained by dividing the gap size by the size of the gap between the pair of electrodes is generated in the gap between the electrodes where the collection of flake graphite particles is located. This electric field simultaneously exerts a Coulomb force sufficient to destroy the interlayer bonds of the basal planes of all graphite particles, which are the carriers of the interlayer bonds of the basal planes of graphite crystals. As a result, it was confirmed that all of the interlayer bonds of the graphite crystals are simultaneously destroyed, and a collection of basal planes of graphite crystals, i.e., graphene, can be produced.

[0022] Example 2 In this example, a graphene conjugate is prepared according to the method described in paragraph 11. The suspension prepared in Example 1 was poured into a shallow cube container measuring 10 cm × 10 cm × 3 cm (depth) so that the amount filled half of the container's volume. After this, vibration accelerations of 0.3 G were applied to the container in three directions (front-back, left-right, and up-down) in turn, and finally vibration acceleration of 0.3 G was applied to the container in the up-down direction. Next, a 10 cm x 10 cm x 2 cm (thickness) flat plate was placed over the suspension in the container so that it was in contact with the suspension, and the container was heated to the boiling point of methanol to vaporize the methanol from the suspension. The vaporized methanol was then collected and reused. Furthermore, nine weights of 10 kg each were placed at equal intervals on the surface of the plate, and after 5 seconds, all the weights were removed from the plate. Furthermore, an impact acceleration of 0.6 G was simultaneously applied to five equally spaced locations on the bottom surface of the container, and the container was peeled off from the graphene conjugate. Furthermore, an impact acceleration of 0.5 G was simultaneously applied to four locations on each side of the flat plate, and the graphene conjugate was peeled off from the flat plate. Note that, upon observation of the side surface of the graphene conjugate, the thickness of the graphene conjugate was found to be only 0.1 μm. Five such graphene conjugates were produced. Next, the surface resistance of the graphene composite was measured at multiple points on its surface using a surface resistance meter (ST-4 surface resistance meter manufactured by Simco Japan Co., Ltd.). 3 Since the surface resistance was Ω / □, the graphene composite has the same surface resistance as a highly conductive metal.

[0023] Example 3 In this example, a new suspension is prepared using 2-pentanol as the alcohol described in paragraph 17 and aluminum nitride as the powder described in paragraph 15. Furthermore, the graphene conjugate prepared in Example 2 is immersed in the new suspension. 800 g of 2-pentanol and 300 g of aluminum nitride (TFZ-N01P, a product of Toyo Aluminum Co., Ltd.) were weighed out, and both were placed in a container. The 2-pentanol was stirred to create a new suspension. The aluminum nitride used was granular, with a particle size of D50 of 1.2 μm, a thermal conductivity of 170 W / (m·K), and a volume resistivity of 10 13 greater than Ω·cm and a density of 3.3 g / cm 3 The graphene composite prepared in Example 2 was immersed in this new suspension, and then the graphene composite was taken out. Five such graphene composites were prepared.

[0024] Example 4 In this example, a graphene conjugated body having aluminum nitride powder adsorbed on its surface is compressed, and the surface of the graphene conjugated body is covered with a collection of friction-welded aluminum nitride powder. The graphene composite prepared in Example 3 was placed on a flat plate measuring 11 cm × 11 cm × 2 cm (thickness), and then another flat plate measuring 11 cm × 11 cm × 2 cm (thickness) was placed on top of the graphene composite. The temperature was raised to 120°C, and then nine weights each weighing 6 kg were placed at equal intervals on the plate. After 5 seconds, all the weights were removed from the plate. Next, an impact acceleration of 0.4 G was simultaneously applied to four points on the side of the flat plate on which the graphene conjugate was placed, and the graphene conjugate was peeled off from the flat plate. Furthermore, an impact acceleration of 0.4 G was simultaneously applied to four points on the side of the flat plate covering the graphene conjugate, and the graphene conjugate was peeled off from the flat plate. After this, the graphene conjugate covered with aluminum nitride powder was removed. Five such samples were produced. Next, the thermal conductivity of the prepared sample was measured. The thermal conductivity of the sample was measured using a cyclic heating diffusivity measurement device (FTC-1 manufactured by Advance Riko Co., Ltd.) based on the cyclic heating method, a type of unsteady state method. The thermal conductivity of the sample at 20°C was 240±10 W / (m·K). This had better thermal conductivity than aluminum nitride. In addition, the sample Surface The insulation resistance was measured using an insulation resistance meter (product IR4082, manufactured by Hioki E.E. Corporation), and a high resistance value of over 4000 MΩ was observed. Furthermore, the mechanical strength of the prepared sample was measured by drop impact. The sample was allowed to drop from a height of 2m five times, but no change was observed in the sample. Furthermore, the sample was allowed to drop from a height of 4m five times, but no change was observed in the sample. Therefore, the prepared sample has excellent impact strength. Furthermore, when the powder on the side of the sample was peeled off and the side was observed, it was found that the sample consisted of three or four aluminum nitride powder particles overlapping each other. Figure 1 shows an enlarged schematic view of a portion of the side of the sample. 1 is the aluminum nitride powder, and 2 is the graphene composite.

[0025] This example is merely an example. In other words, the size and thickness of the graphene composite produced in Example 2 vary depending on the size of the container into which the suspension is poured and the amount of the suspension poured. Furthermore, the new suspension produced in Example 3 is not limited to 2-pentanol, and various alcohols described in paragraph 17 can be used. Furthermore, various powders described in paragraph 15 can be used as powders with excellent thermal conductivity. Furthermore, the graphene composite produced in Example 4 S The thermal conductivity of the sheet varies depending on the powder material and the viscosity of the new suspension prepared in Example 3. S The insulation resistance of the port varies depending on the viscosity of the new suspension prepared in Example 3. S The mechanical strength of the sheet varies depending on the magnitude of the compressive load applied to the flat plate in Example 4. On the other hand, the sample prepared in Example 4 S The thermal conductivity of the S The thermal conductivity of the SiO2 film is two orders of magnitude higher than that of the SiO2 film prepared in Example 4. S The insulation resistance of the sheet is two orders of magnitude greater than that of the conventional sheet. S The impact strength of the car is excellent, but the weight is less than that of conventional S The weight of the present invention is two orders of magnitude less than that of the conventional one. S The material composition and sheet manufacturing method are different from conventional S It is based on a completely new material and a new manufacturing method that is completely different from conventional S It has properties that far surpass those of rhododendron. [Explanation of symbols]

[0026] 1. Aluminum nitride powder 2. Graphene composite

Claims

1. A method for producing a thin, lightweight, and mechanically strong sheet having excellent thermal conductivity and insulation properties, which is made by covering a graphene joint formed by friction welding overlapping graphene pieces with an aggregation of insulating and thermally conductive powder, is as follows: A collection of flake graphite particles or a collection of lump graphite particles is spread evenly on the surface of one of two parallel flat electrode plates, and the one parallel flat electrode plate is immersed in methanol filled in a first container. The other parallel flat electrode plate is placed on top of the one parallel flat electrode plate with the collection of flake graphite particles or the collection of lump graphite particles interposed therebetween, and the electrode pair consisting of the two parallel flat electrode plates is immersed in the methanol. Thereafter, a direct current potential difference of a predetermined magnitude is applied to the gap between the electrode plate pair, and an electric field corresponding to the value obtained by dividing the magnitude of the potential difference by the size of the gap between the electrode plate pair is generated between the collection of flake graphite particles or the lump graphite particles. a first step of applying an electric field to a collection of graphite particles, which simultaneously destroys all interlayer bonds of the basal planes of the graphite crystals forming the flake graphite particles or the lump graphite particles, and depositing collections of graphene made of the basal planes in the gap between the pair of electrodes; thereafter, widening the gap between the pair of electrodes, tilting the pair of electrodes in the methanol, and repeatedly applying vibration accelerations in three directions, left and right, front and back, and up and down, to the first container in turn to move the collections of graphene from the gap between the pair of electrodes into the methanol; thereafter, removing the two parallel flat electrodes from the first container, and creating collections of graphene dispersed in methanol in the first container; a second step of operating an ultrasonic homogenizer device in the first container, repeatedly applying shock waves to the graphene aggregates through the methanol, and separating the graphene aggregates into individual graphene sheets in the methanol, and then removing the homogenizer device from the first container, and creating a suspension in the first container consisting of the graphene aggregates separated into individual graphene sheets in the methanol; A suspension having a predetermined weight of the suspension is poured into a second container, and vibration accelerations in three directions, i.e., front-to-back, left-to-right, and up-to-down, are applied to the second container in turn and repeatedly. Finally, vibration acceleration in the up-to-down direction is applied, causing the graphene clusters in the suspension to randomly align in the suspension with their faces facing up. Further, a first flat plate having the same size as the inside of the second container is placed over the suspension in the second container so as to be in contact with the suspension. Further, the second container is heated to the boiling point of the methanol, and the methanol is evaporated from the suspension. The graphene clusters are then stacked with their faces facing up. Thereafter, the entire surface of the first flat plate is uniformly compressed. a third step of compressing the stacked graphene pieces with the surface facing up, friction-welding the stacked graphene pieces with the surface facing up, and forming a graphene conjugate made up of the friction-welded graphene conjugate on a bottom surface of the second container in the shape of the bottom surface of the second container; thereafter, applying impact acceleration simultaneously to a plurality of locations on the bottom surface of the second container to peel the graphene conjugate from the bottom surface of the second container; and further applying impact acceleration smaller than the above impact acceleration simultaneously to a plurality of locations on a side surface of the first flat plate to peel the graphene conjugate from the first flat plate, thereby removing the graphene conjugate; a fourth step of weighing the alcohol and the powder mass at a predetermined weight ratio in which the ratio of the weight of the insulating and thermally conductive powder mass to the weight of the alcohol having a viscosity of 4-6 mPa·sec at 20°C is less than 1, pouring the weighed alcohol and powder into a third container, and stirring the alcohol in the third container to prepare a new suspension in which the powder mass is dispersed in the alcohol; a fifth step of immersing the removed graphene conjugate in the new suspension to cause the new suspension to adhere to the graphene conjugate, and then removing the graphene conjugate from the new suspension; The graphene conjugate is placed on the second flat plate so that the entire surface of the graphene conjugate to which the new suspension is attached overlaps the second flat plate, and then a third flat plate having the same size as the second flat plate is placed over the entire surface of the graphene conjugate. The temperature is then raised to the boiling point of the alcohol to evaporate the alcohol from the new suspension attached to the graphene conjugate, and the entire surface of the graphene conjugate is covered with the powder. Thereafter, the entire surface of the third flat plate is uniformly compressed, thereby forming a powder conjugate that is in contact with the surface of the graphene conjugate. a sixth step of simultaneously applying an impact acceleration to a plurality of locations on a side surface of the second flat plate to peel the graphene conjugate from the second flat plate, and further simultaneously applying an impact acceleration equivalent to the impact acceleration to a plurality of locations on a side surface of the third flat plate to peel the graphene conjugate from the third flat plate, and removing the graphene conjugate; By successively carrying out these six steps, a sheet having excellent thermal conductivity and insulation properties, a thin, lightweight sheet having mechanical strength, and a structure in which a graphene joint formed by friction welding overlapping graphene pieces is covered with an aggregation of insulating and thermally conductive powder is produced.

2. The sheet creation method according to claim 1 comprises: A method for producing a sheet according to claim 1, wherein the insulating and thermally conductive powder according to claim 1 is any one of powders consisting of alumina, boron nitride, silicon nitride, or aluminum nitride, and the any one of powders is used as the insulating and thermally conductive powder according to claim 1, and a sheet is produced according to the method for producing a sheet according to claim 1.

3. The sheet creation method according to claim 1 comprises:

2. A method for producing a sheet according to claim 1, wherein the alcohol having a viscosity of 4-6 mPa sec at 20°C according to claim 1 is any one of 2-pentanol, 3-methyl-1-butanol, tert-amyl alcohol, 2-butanol, 2-methyl-1-butanol, 2-heptanol, isobutyl alcohol, 4-methyl-2-pentanol, 3-pentanol, and 2-octanol, and wherein the any one of the alcohols is used as the coke having a viscosity of 4-6 mPa sec at 20°C according to claim 1, and a sheet is produced according to the method for producing a sheet according to claim 1.

4. A method for integrating the sheet produced by the method according to claim 1 with a part or a substrate comprises the steps of: A method for integrating a sheet prepared by the method described in claim 1 with a part or substrate, comprising: preparing a sheet according to the method described in claim 1; placing a part or substrate on the surface of the sheet; and uniformly compressing the entire surface of the part or substrate; thereby causing a collection of insulating and thermally conductive powder covering the surface of the sheet to be frictionally welded to the surface of the part or substrate, thereby integrating the sheet with the part or substrate.

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