JP2008208316A - Carbon fiber composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart electric insulation properties to a molded product of a resin composition containing carbon fiber being excellent in heat conductivity and having high degree of graphitization. <P>SOLUTION: A heat-conductive composite material is provided. The composite material is prepared by laminating an electrically insulative film or forming an electrically insulative film layer comprising a thin metal oxide membrane, a coating film of an inorganic polymer or a coating film of an organic polymer on a cross sectional face or a surface of the molded product of a composition comprising a carbon fiber aggregate and a resin matrix. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to improvement of a heat conductive material made of partially graphitized carbon fiber, and particularly to an improved technique for imparting electrical insulation. More specifically, a pitch-based carbon fiber is used as a raw material, subjected to graphitization treatment, impregnated with a matrix resin to form a composite material, and the carbon fiber-containing composite material is molded into a molded product, and then the molded product. The present invention relates to an electrically insulating and thermally conductive composite laminate obtained by applying an electrical insulation treatment to the surface of the substrate.

  Carbon fiber is derived from the structure of its raw material, and is a linear carbon fiber made from a chain (linear) polymer, a linear carbon fiber made from polyacrylonitrile (PAN), and a plane made from a cyclic condensation polymer. It can be classified as a carbon fiber. Conventionally, chain carbon fiber uses the characteristics that strength and elastic modulus are remarkably higher than ordinary synthetic polymers, and is used for aerospace and space equipment, construction and civil engineering materials, industrial robots, sports and leisure equipment. It is used in a wide range of fields. In particular, PAN-based carbon fibers are often used for applications that utilize their mechanical strength, and pitch-based carbon fibers are often used for fields that use elastic modulus.

  The carbon fiber is obtained by making the above-mentioned raw material into a fiber in a spinning process, then subjecting it to an infusibilizing treatment, and further applying a crystallization treatment at a high temperature. By this crystallization heat treatment, the carbon fiber partially becomes graphite crystals. Compared to carbon fibers derived from linear polymers, carbon fibers having a network structure using pitch as a raw material are more easily graphitized, have higher crystallinity, and grow larger in crystal size.

  By the way, in recent years, in the field of communication and information industries, heat generation by a high-speed CPU and heat generation by Joule heat of an electronic circuit are being recognized as serious problems. In order to solve these problems, it is pointed out that it is necessary to consider a technique for efficiently processing heat, so-called thermal management.

  In order to realize this thermal management, it is common to use a metal material having high thermal conductivity such as metal, metal oxide, metal nitride, metal oxynitride or alloy. A typical example is metal die casting. However, in order to produce a housing for an electrical component having a complicated shape, the above-described graphite fiber material is used as a heat conducting material, and a heat-resistant material that forms a matrix is blended with it to be used as a composite material. Is a preferred embodiment. However, the thermal conductivity of the synthetic resin applicable to the matrix is about 1/100 or less that of the graphite fiber, and as a result, a large amount of graphite fiber needs to be blended as a composite material.

  However, the addition of a large amount of partially graphitized carbon fiber filler in the composite material leads to instability of moldability and impairs practicality as a molded product. For such reasons, a highly thermally conductive carbon fiber filler in which consideration is given to a shape capable of efficiently expressing thermal conductivity is demanded.

  Carbon fibers have higher thermal conductivity than other synthetic polymers, but further improvements in thermal conductivity are being studied for thermal management applications. However, the thermal conductivity of commercially available PAN-based carbon fibers is usually less than 100 W / (m · K). This is because PAN-based carbon fibers are so-called “non-graphitizable” carbon fibers, and it is very difficult to increase the degree of graphitization responsible for heat conduction. On the other hand, pitch-based carbon fibers are called “easily graphitized” carbon fibers, and can have a higher degree of graphitization than PAN-based carbon fibers, so that high thermal conductivity is easily achieved. Therefore, there is an expectation that a high thermal conductivity carbon fiber filler can be obtained after high thermal conductivity can be expressed and the shape as a carbon fiber aggregate is studied.

  However, since it is difficult to directly process the carbon fiber alone into the heat conductive member, it is necessary to use a special means. Therefore, like a metallic filler or the like, it is required to make a composite material of some matrix and carbon fiber and mold it into a molded body to improve the thermal conductivity of the molded body.

  And in order for a molded object to achieve predetermined | prescribed heat conduction, the carbon fiber filler which mainly bears heat conduction needs to form the network in three dimensions. For example, in the case of spherical fillers of uniform size, it can be seen that the filler network in the molded body depends on the dispersion state but assumes a percolation behavior when uniform dispersion is assumed. Thus, in order to obtain sufficient thermal conductivity and electrical conductivity as a molded article, it is necessary to add a certain amount of filler. However, when forming a molded body, a thickening action or a non-uniform dispersion state occurs between the medium and the filler, and it may be difficult to disperse the medium and the filler at a predetermined concentration. Even if the filler addition amount is small, an effective composition is desired.

  In view of such a background, studies have been made to give fillers three-dimensional crosslinking. For example, Patent Document 1 discloses an attempt to transport a heat flow by forming a metal network. However, it is considered that a very high level of technology is required for dispersion into the matrix. Patent Document 2 discloses that alloying causes the matrix and the filler to melt simultaneously, and as a result, high thermal conductivity is achieved while maintaining formability.

However, the addition of a metal material whose specific gravity is larger than that of the resin increases the specific gravity of the resin composition, and uses such as a heat sink for an integrated circuit and a CPU of an electric computer, etc. to discuss weight reduction on the order of 1 g. It must be said that it is disadvantageous.
Furthermore, depending on the application, there are applications that require electrical insulation while maintaining thermal conductivity. Since graphitized carbon fiber has a high electrical conductivity, it is necessary to reliably block the conductive portion with an insulating material.

Japanese Patent Laid-Open No. 6-196684 International Publication No. 03/029352 Pamphlet

  It is necessary to obtain a resin composition having high thermal conductivity and at the same time having electrical insulation. In order to achieve this problem, a carbon fiber with a high graphite component, which is a material with high thermal conductivity, is demanded. Furthermore, sufficient thermal conductivity is exhibited in the final use state, and electrical insulation is also achieved. It is necessary to prepare.

  The inventors of the present invention aim to improve thermal conductivity in a final molded body such as a heat radiating member. For example, the main component is pitch-based carbon fiber having high thermal conductivity as a thermal conductive material. The inventors have found that by controlling the size, surface shape and microstructure, and appropriately dispersing in the matrix, it is possible to satisfy the electrical insulation while simultaneously maintaining high thermal conductivity, thereby reaching the present invention.

  Basically, when carbon fiber with a high degree of graphitization is used as a raw material, the impregnation of the matrix, the insulation treatment, and the like are accompanied by the action of hindering the thermal conductivity and never improve the thermal conductivity. Therefore, it is possible to apply a means for ensuring the thermal conductivity of the molded product / laminate by applying an electrical insulation treatment after raising the thermal conductivity to a very high level.

  That is, the first embodiment of the present invention is to maintain a state where the matrix itself has electrical insulation as the composite material for molding use according to claim 1, and can express the insulation as it is. A heat conductive material comprising a carbon fiber aggregate and a matrix (resin) impregnated with the carbon fiber aggregate, wherein the entire surface of the carbon fiber aggregate including its end face is covered with the matrix (go) It is a carbon fiber composite material formed by forming an electrically insulating layer.

  The invention of claim 10, claim 11, or claim 12, which is the second embodiment of the present invention, ensures electrical insulation in a molded product obtained by molding the composite material described above. An electrical insulating material is applied to the surface of the molded product, or an electrical insulating film is formed on a cross section of the molded product, and the appearance of inserting the electrical insulating film is apparent. Therefore, in this specification, this state is displayed when an electrical insulating film is inserted into the molded product. Furthermore, the electrical insulation means that the surface resistance is 1E6Ω / □ (Ω / sq.) Or more. In short, a metal oxide thin film, an electrically insulating inorganic polymer coating film is formed on the surface or an arbitrary cross section of a molded product formed by molding a carbon fiber composite material containing a carbon fiber aggregate and a matrix. Alternatively, it is a carbon fiber composite laminate formed by forming (laminating or inserting) an electrical insulating layer made of an organic polymer coating.

  As a preferred embodiment of the present invention, it is clearly indicated that carbon fibers having excellent thermal conductivity and high degree of graphitization should be selected, and cyclic hydrocarbons having condensed condensed heterocyclic rings, that is, pitch-based carbon raw materials should be used. is doing.

  The carbon fiber aggregate accumulated in a mat shape obtained through the spinning process is made of, for example, a pitch-based carbon fiber filler whose observation surface by a scanning electron microscope is substantially flat, and an average fiber diameter observed by an optical microscope (D1) is in the range of 5 μm to 20 μm, the average fiber diameter dispersion (S1) percentage with respect to the average fiber diameter (D1) is 5 to 18%, and the end face of the carbon fiber filler is closed, the average It is clearly shown that the fiber length (L1) is in the range of 10 μm or more and 700 μm or less and the aspect ratio of L1 to D1 is in the range of 1 to 100 exhibits the optimum graphitization rate.

  When the graphitization rate is high, the true density of the carbon fiber is in the range of 1.5 to 2.2 g / cc, and the thermal conductivity in the fiber axis direction is 300 W / (m · K) or more. The crystal size in the thickness direction of the hexagonal mesh surface is 10 nm or more, and the crystal size in the growth direction of the hexagonal mesh surface is also grown to 8 nm or more.

  In the present invention, the carbon fiber aggregate is not limited to a carbon fiber filler having a flat and smooth surface as described above, and its end face is closed as a graphene sheet. A composition comprising the following matrix and a thermally conductive carbon fiber aggregate, wherein the matrix exhibits electrical insulation, and the carbon fiber aggregate is a pitch-based carbon fiber having a different fiber diameter and / or fiber length. A carbon fiber composite material having a composition having a high carbon fiber filling rate when combined with a matrix is also a preferable material.

These composite materials of the present invention include a carbon fiber aggregate and a matrix, and are characterized by containing the carbon fiber material in a volume fraction of 3 to 60% by volume with respect to the matrix.
The matrix is a thermoplastic resin and / or a thermosetting resin. For example, the thermoplastic resin may be polycarbonates, polyethylene terephthalates, polyethylene 2,6 naphthalates, nylons, polypropylenes, polyethylenes, polyepoxyether ketones. And at least one resin selected from the group of polyphenylene sulfides. For example, the thermosetting resin is at least one resin selected from the group of epoxies, acrylics, urethanes, silicones, and phenols. And the heat conductivity of the composite material in the state shape | molded in flat form or its molded object is 2 W / (m * K) or more.

  The composite material of the present invention is formed into a molded product by at least one molding means selected from the group of injection molding, press molding, calendar molding, roll molding, extrusion molding, cast molding, and blow molding. Can be molded.

Furthermore, when the composite molded product formed by molding the carbon fiber composite material does not maintain electrical insulation, an insulation treatment can be performed. This insulation treatment is a process of forming an electrically insulating layer made of a metal oxide thin film, an inorganic polymer coating film or an organic polymer coating film on the surface of the molded product, if necessary, on an arbitrary cross section of the molded product. Achieved by law. Details have already been mentioned.
Examples of suitable applications are a heat radiating member for electronic parts, a radio wave shielding plate, or a heat exchanger mainly composed of the composite molded article / laminate of the present invention.

  The composite molded product of the present invention is processed into a heat radiating member of an electronic component as a main material, and can be used for a heat radiating case such as a heat sink for an integrated circuit or a CPU of an electric computer. Moreover, the carbon fiber derived from the pitch-based material can be applied to a radio wave shielding plate by being excellent in radio wave shielding performance in a frequency band of several GHz.

  Furthermore, depending on the application, there are applications that require electrical insulation while maintaining thermal conductivity. Since the graphitized carbon fiber has a high electrical conductivity, the conductive portion can be reliably cut off by the insulating material.

  The pitch-based carbon fiber filler that can be used in the present invention has a specific shape and is controlled in size, thereby imparting high thermal conductivity to the composite molded body while suppressing an increase in the viscosity of the matrix. Therefore, a composite molding material having good moldability and high thermal conductivity can be obtained.

Next, embodiments of the present invention will be described in detail.
The carbon fiber aggregate of the present invention is composed of pitch-based carbon fibers. Examples of the carbon fiber aggregate pitch carbon fiber material that can be used include condensed polycyclic hydrocarbon compounds such as naphthalene and phenanthrene, condensed heterocyclic compounds such as petroleum pitch and coal pitch, and the like. In particular, condensed polycyclic hydrocarbon compounds such as naphthalene and phenanthrene are preferred. In particular, an optically anisotropic pitch, that is, a mesophase pitch is preferable. These may be used singly or in appropriate combination of two or more, but the use of mesophase pitch alone can increase the graphitization rate in the graphitization treatment, and consequently The thermal conductivity of the carbon fiber can be improved, which is a preferred embodiment.

The softening point of the raw material pitch can be determined by the Mettler method, and is preferably in the range of 230 ° C. or higher and 340 ° C. or lower. If the softening point is lower than 230 ° C., fusion between fibers or large heat shrinkage occurs during infusibilization. If the temperature is higher than 340 ° C., the pitch is thermally decomposed in the spinning process, which tends to make the spinning molding difficult. Furthermore, under high temperature spinning conditions, gas components are generated, bubbles are generated inside the spun fibers, leading to strength deterioration, and yarn breakage is likely to occur.
The raw material pitch is spun by a melt blow method, and then becomes pitch-based carbon fiber having a relatively short fiber length by various processes of infusibilization, firing, milling, sieving, and graphitization.

Each process will be described below.
In the present invention, there is no particular restriction on the shape of the spinning nozzle when spinning the pitch fiber that is the raw material of the pitch-based carbon fiber. However, the nozzle hole length / hole diameter ratio is preferably smaller than 3, more preferably about 1.5.

  There are no particular restrictions on the nozzle temperature during spinning, and there is no problem as long as the temperature can maintain a stable spinning state. If the viscosity of the raw material pitch is in an appropriate range, the spinning state is stabilized, that is, the pitch viscosity during spinning is 0.1 to 20 Pa · S, preferably 8 to 16 Pa · S, more preferably 10 to 14 Pa · S. It is sufficient that the temperature is S.

  The pitch fibers drawn out from the nozzle holes are shortened by blowing a gas having a linear velocity of 100 to 10000 m per minute heated to 100 to 370 ° C. in the vicinity of the thinning point. As the gas to be blown, air, nitrogen, argon or the like can be used, but air is preferable from the viewpoint of cost performance.

The pitch fibers are collected on a wire mesh belt, become a continuous mat, and are further cross-wrapped to form a web having a predetermined basis weight (weight per unit area).
The web made of pitch fibers thus obtained has a three-dimensional randomness due to the interlace of the fibers. This web can be infusibilized by known methods. This infusibilization temperature is 200 to 300 ° C.

  Infusibilization is achieved by applying a heat treatment for a certain time at a temperature of 200 to 300 ° C. using air or a mixed gas obtained by adding ozone, nitrogen dioxide, nitrogen, oxygen, iodine or bromine to air. Considering safety and convenience, it is desirable to carry out in air.

  The infusible pitch fiber is then fired in a temperature range of 700 to 900 ° C. in a vacuum or in an inert gas such as nitrogen, argon or krypton. Usually, the calcination is performed using nitrogen which is inexpensive at normal pressure.

  The web made of infusibilized and fired pitch fibers is further milled and sieved in order to further shorten the fibers and to obtain a predetermined fiber length. For milling, a pulverizer or cutting machine such as a Victory mill, a jet mill, or a high-speed rotary mill is used. In order to perform milling efficiently, a method of cutting fibers in a direction perpendicular to the fiber axis by rotating a rotor to which blades are attached at high speed is appropriate.

  The average fiber length of the fibers produced by milling is controlled by adjusting the rotational speed of the rotor, the angle of the blade, and the like. Furthermore, it divides into 10-60 micrometers by a sieve, More preferably, it is 15-50 micrometers. Alternatively, it is divided into 100 to 700 μm, more preferably 100 to 300 μm. Such adjustment of the average fiber length can be carried out by combining the coarseness of the sieve mesh.

  The fiber after the milling and sieving is heated to 2300-3500 ° C. and graphitized to obtain a final pitch-based carbon short fiber. Graphitization is performed in a non-oxidizing atmosphere in an Atchison furnace or the like.

  Next, the shape of the pitch-based carbon fiber filler of the present invention will be described. When the shape of the filler end face is observed with a transmission electron microscope, the pitch-based carbon fiber of the present invention has a structure in which the graphene sheet is closed. When the end surface of the filler is closed as a graphene sheet, generation of extra functional groups and localization of electrons due to the shape do not occur, so that the concentration of impurities such as water can be reduced. In particular, the present invention can be applied to a filler having a fiber length shorter than 1 mm, but a structure in which the graphene sheet is closed is particularly preferable because the ratio of the end face to the filler surface area is increased.

  Note that the graphene sheet is closed means that the end of the graphene sheet itself constituting the carbon fiber is not exposed at the end of the carbon fiber, the graphite layer is curved in a substantially U shape, and the curved portion is the end of the carbon fiber. It is in the state exposed to the part.

The pitch-based carbon fiber filler used in the present invention has a substantially flat observation surface with a scanning electron microscope. Here, “substantially flat” means that the surface does not have severe unevenness like a fibril structure, and when there is intense unevenness on the surface of the filler, the surface area increases upon kneading with the matrix resin. It is desirable that the surface irregularities be as small as possible, since this causes an increase in the viscosity accompanying this and lowers the moldability.
The pitch-based carbon fiber filler described above can be easily obtained by performing graphitization after milling.

  The average fiber diameter (D1) observed with an optical microscope of the pitch-based carbon fiber filler of the present invention is preferably 5 to 20 μm, more preferably 7 to 12 μm. When the fiber diameter is larger than 20 μm, adjacent fibers are likely to be fused in the infusibilization process. When the fiber diameter is less than 7 μm, the surface area per weight of the pitch-based carbon fiber filler is increased, and the fiber surface is substantially Even if it is flat, the formability is lowered in the same manner as the fiber having irregularities on the surface, and it is inappropriate in practice. The percentage of the fiber diameter dispersion (S1), which is the dispersion of the fiber diameter with respect to the average fiber diameter (D1) observed with an optical microscope, is preferably in the range of 5 to 18%. More preferably, it is 5 to 15% of range.

  The average fiber length (L) of the pitch-based carbon fiber filler of the present invention is preferably 10 to 700 μm. The fiber length has an optimum value depending on the application, but in the case of aiming at a reinforcing effect that the filler is secondarily developed, a range of 300 to 700 μm is preferable. More preferably, it is the range of 300-500 micrometers. On the other hand, when the filler is used for creating a heat transfer path, that is, for a heat radiating member, the fiber length is preferably in the range of 10 to 300 μm. More preferably, it is the range of 10-100 micrometers. When L1 is shorter than 10 μm, it is difficult to maintain the fibrous shape. When L1 exceeds 700 μm, the bulk density becomes small and mixing with the matrix component becomes difficult. The ratio of L1 to D1 (L / D) is in the range of 1-100.

  L / D also depends on the average fiber length. On the other hand, when L / D is smaller than 1, powder falling in the final molded product becomes remarkable. On the other hand, if L / D exceeds 100, the ratio of fibers that breaks increases, making it difficult to express the original performance. In a more preferred embodiment, the aspect ratio is about 1.5 to 10 when the average fiber length is 10 to 100 μm, and the aspect ratio is 30 to 50 when the average fiber length is 300 to 500 μm.

In the present invention, the true density of the pitch-based carbon fiber filler strongly depends on the graphitization temperature, but is preferably in the range of 1.5 to 2.2 g / cc. More preferably, it is 1.8-2.2 g / cc. The thermal conductivity in the fiber axis direction of the pitch-based carbon fiber is 300 W / (m · K) or more, and more preferably 400 W / (m · K) or more.
In addition, the pitch-based carbon fiber filler has a hexagonal mesh surface with a crystal size in the thickness direction of 10 nm or more, and a hexagonal mesh surface in the growth direction with a crystal size of 8 nm or more.

  The crystal size corresponds to graphitization in both the thickness direction of the hexagonal mesh surface and the growth direction of the hexagonal mesh surface, and in order to develop thermophysical properties, crystal grains of a certain size or larger are required. is necessary. The crystal size in the thickness direction of the hexagonal mesh surface and the crystal size in the growth direction of the hexagonal mesh surface can be obtained by an X-ray diffraction method. The measurement method should be the concentration method, and the Gakushin method should be used as the analysis method. The crystal size in the thickness direction of the hexagonal mesh plane is obtained using diffraction lines from the (002) plane, and the crystal size in the growth direction of the hexagonal mesh plane is obtained using diffraction lines from the (110) plane, respectively. Can do.

  In the present invention, the carbon fiber aggregate may be prepared after sizing the pitch-based carbon fiber filler. Convergence can be improved by adding a sizing agent to the filler in an amount of 0.01 to 10% by weight, preferably 0.1 to 2.5% by weight. As the sizing agent, those usually used can be used. Specifically, an epoxy compound, a water-soluble polyamide compound, a saturated polyester, an unsaturated polyester, polyvinyl acetate, water, alcohol, glycol can be used alone or as a mixture thereof. it can. Such surface treatment is an effective means because the bulk density can be increased. However, since excessive sizing agent adhesion causes thermal resistance that hinders heat transfer, it is required to adjust the amount of sizing material applied according to the required physical properties.

  In addition, when producing a carbon fiber aggregate with a pitch-type carbon fiber filler, you may attach a sizing agent after surface-treating. Surface treatment methods include electrolytic treatment such as electrolytic oxidation, electroless plating, electrolytic plating, physical vapor deposition such as vacuum deposition, sputtering, and ion plating, chemical vapor deposition, painting, dipping, and fine particles. The surface may be coated with metal or ceramics by means such as a mechanochemical method for mechanically fixing.

  In the present invention, a pitch-based carbon fiber aggregate and a matrix are mixed to produce a composite molded body. At this time, the pitch-based carbon fiber aggregate is added in a volume fraction of 3 to 60% with respect to the matrix. On the other hand, if the addition amount is less than 3% by volume, it is difficult to ensure sufficient thermal conductivity. On the other hand, it is often difficult in practice to add more than 60% by volume of pitch-based carbon fiber aggregates to the matrix.

  As the matrix, either a thermoplastic resin or a thermosetting resin is applied. Further, as the matrix, a thermoplastic resin and a thermosetting resin can be appropriately mixed and used in order to develop desired physical properties in the composite molded product.

  The thermoplastic resin should be selected from at least one selected from the group consisting of polycarbonates, polyethylene terephthalates, polyethylene 2,6 naphthalates, nylons, polypropylenes, polyethylenes, polyether ether ketones, and polyphenylene sulfides. Can do.

  More specifically, ethylene-α-olefin copolymers such as polyethylene, polypropylene, ethylene-propylene copolymer, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer , Polyvinyl alcohol, polyacetal, fluorine resin (polyvinylidene fluoride, polytetrafluoroethylene, etc.), polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, ABS resin, polyphenylene ether (PPE) ) Resin, modified PPE resin, aliphatic polyamide, aromatic polyamide, polyimide, polyamideimide, polymethacrylic acid (polymethacrylate such as polymethylmethacrylate) Ester), polyacrylic acids, polycarbonate, polyphenylene sulfide, polysulfone, polyether sulfone, polyether nitrile, polyether ketone, polyketone, liquid crystal polymer, ionomer and the like. And as a matrix, 1 type may be used individually from these, 2 or more types may be used in combination suitably, and the polymer alloy which consists of 2 or more types of polymeric materials may be used.

  Examples of the thermosetting resin include epoxies, acrylics, urethanes, silicones, phenols, imides, thermosetting modified PPEs, thermosetting PPEs, and the like. Or two or more types may be used in appropriate combination.

  The composite molded product of the present invention is prepared by mixing a carbon fiber aggregate and a matrix. During mixing, a kneader, a mixer, a blender, a roll, an extruder, a milling machine, a self-revolving stirrer, etc. These mixing devices or kneading devices are preferably used. The composite molded body can be molded by a molding method such as an injection molding method, a press molding method, a calendar molding method, a roll molding method, an extrusion manufacturing method, a casting molding method, or a blow molding method.

Molding conditions vary depending on the matrix and molding technique means. In the case of a thermoplastic resin, molding is performed in a state where the temperature is higher than the melting temperature of the resin. In the case where the matrix is a thermosetting resin, a method of heating to the curing temperature of the resin in an appropriate mold can be exemplified.
The carbon fiber reinforced composite material can also be obtained by shaping the matrix resin into a flat shape or the like in advance and press-molding it in a state of being laminated with a pitch-based carbon fiber sheet in which carbon fibers are dispersed.

  A carbon fiber composite comprising a metal oxide thin film, an inorganic polymer coating film or an organic polymer coating film formed on the surface or cross section of a molded product formed by molding a carbon fiber composite material. Laminates can be obtained and this product is of course electrically insulating. The electrical insulation performance can also be obtained by laminating a molded product obtained by molding a carbon fiber composite material and an electrical insulation layer. The thickness of the metal oxide thin film is preferably 0.002 to 2 μm. The thickness of the coating film of the inorganic polymer and the coating film of the organic polymer may be in the range of 1 μm to 100 μm. More preferably, it is the range of 1 micrometer-30 micrometers.

  On the surface of the molded product formed of the carbon fiber composite material of the present invention, a metal oxide and / or nitride and / or oxynitride selected from the group consisting of aluminum, silicon, boron and zinc and An electrical insulating layer made of an organic polymer coating film containing fine particles of carbide can be formed. The size of the fine particles is preferably 1 to 20 μm, more preferably 1 to 10 μm. Although there is no restriction | limiting as an organic polymer, The same as the material used for a matrix, or a thermosetting resin is preferable from a viewpoint of handling. In particular, a material having a low viscosity before curing is preferable because it has a high degree of freedom in processing steps.

The organic polymer material containing the fine particles preferably has a thickness of 1 to 100 μm. This polymer material can be applied by a known method, and examples thereof include a dipping method, a Meyer bar method, a gravure method, and a micro gravure method. The organic polymer material containing the fine particles can be diluted with a solvent to adjust the thickness. The solvent depends on the organic polymer material. For example, when a silicone resin is used for the organic polymer material, hexane / heptane can be used. Further, methyl isobutyl ketone (MIBK) or 1-methoxy-2-propanol (1M2P) may be used for adjusting the evaporation rate of the solvent.
If it exceeds 100 μm, the thermal conductivity may be significantly impaired. If the thickness is less than 1 μm, handling is extremely difficult.

  The surface of a molded product formed by molding a thermally conductive carbon fiber composite material including a carbon fiber aggregate and a matrix may be subjected to surface treatment and then an electrical insulating layer formed. As the surface treatment method, the surface may be modified by oxidation treatment such as electrolytic oxidation, or by treatment with a coupling agent or sizing agent. Also, by means such as electroless plating, electrolytic plating, physical vapor deposition such as vacuum deposition, sputtering, ion plating, chemical vapor deposition, painting, dipping, and mechanochemical methods for mechanically fixing fine particles. A metal or ceramic coated on the surface may be used.

  When the composite molded product of the present invention is molded into a flat plate shape and the thermal conductivity is measured, it shows a thermal conductivity of 2 W / (m · K) or more. The thermal conductivity of 2 W / (m · K) is about one digit (about 10 times) higher than that of the polymer material used as the matrix. More preferably, it is 5 W / (m · K) or more, and further preferably 10 W / (m · K) or more. As the upper limit, it cannot be particularly provided, but it is considered that the upper limit cannot be 500 W / (m · K) or more, which is the heat conduction of the pitch-based carbon fiber filler.

  The composite molded product of the present invention can be used as a heat sink for electronic components by utilizing its high thermal conductivity. In addition, since high thermal conductivity can be obtained by increasing the amount of pitch-based carbon fiber filler added, automobiles that require relatively high heat resistance in electronic components and industrial power modules that require large currents It can be suitably used for a connector or the like. More specifically, it can be used for a heat sink, a semiconductor package component, a heat sink, a heat spreader, a die pad, a printed wiring board, a cooling fan component, a housing, and the like. It can also be used as a part of a heat exchanger. Can be used for heat pipes. Furthermore, the radio wave shielding property of the pitch-based carbon fiber filler is utilized, and it can be suitably used particularly as a radio wave shielding member in the GHz band.

Examples are shown below, but the present invention is not limited thereto.
(1) Average fiber diameter and fiber diameter dispersion of pitch-based carbon short fiber filler:
The pitch-based carbon fiber filler that had undergone graphitization was determined by photographing 10 fields of view at 400 times under an optical microscope.
(2) Average fiber length of pitch-based carbon short fiber filler:
The pitch-based short carbon fiber filler that had undergone graphitization was determined by photographing 10 visual fields under an optical microscope. The magnification was appropriately adjusted according to the yarn length.
(3) True density of pitch-based carbon short fiber filler:
It calculated | required using the specific gravity method.
(4) Crystal size:
Obtained by X-ray diffraction, the crystallite size derived from the thickness direction of the hexagonal mesh surface is obtained using diffraction lines from the (002) plane, and the crystallite size derived from the growth direction of the hexagonal mesh surface is the (110) plane. It was determined using the diffraction line from. In addition, the request was made in accordance with the Gakushin Law.
(5) Thermal conductivity of pitch-based carbon short fiber filler:
The resistivity of pitch-based short carbon fibers after graphitization prepared under the same conditions except for the pulverization step is measured, and the relationship between the thermal conductivity and electrical resistivity disclosed in JP-A-11-117143 is expressed. It calculated | required from following formula (1).
[Equation 1]
K = 1272.4 / ER-49.4 (1)
Here, K represents the thermal conductivity W / (m · K) of the pitch-based short carbon fiber after graphitization, and ER represents the electrical specific resistance μΩm of the same pitch-based short carbon fiber.
(6) Thermal conductivity of flat molded body:
Measured with QTM-500 manufactured by Kyoto Electronics.
(7) Surface resistance:
The measurement was performed with a Loresta EP manufactured by Dia Instruments.

[Experimental Example 1]
A pitch made of a condensed polycyclic hydrocarbon compound was used as a main raw material. The optical anisotropy ratio was 100%, and the softening point was 281 ° C. A spinneret having a circular hole with a diameter of 0.2 mm was used, heated air was ejected from the slit at a linear velocity of 5000 m / min, and the melt pitch was pulled to produce pitch fibers having an average fiber diameter of 15 μm. The spun fibers were collected on a belt to form a mat, and a web made of pitch fibers having a basis weight of 320 g / m ² was obtained by cross-wrapping.

  This web was infusibilized by raising the temperature from 175 ° C. to 290 ° C. in air at an average temperature rising rate of 7 ° C./min. The infusible web was fired at 700 ° C. in a nitrogen atmosphere and then milled, and sieved to a carbon fiber filler having an average fiber length of 25 μm. Then, it graphitized by heat-processing at 3000 degreeC with the electric furnace made into the non-oxidizing atmosphere, and it was set as the pitch-type carbon short fiber filler. The average fiber diameter was 9.7 μm. The percentage of the fiber diameter dispersion to the average fiber diameter was 14%. The true density was 2.16 g / cc.

The image was observed with a transmission electron microscope at a magnification of 1,000,000 times and magnified on a photograph at 4 million times. It was confirmed that the graphene sheet was closed at the end face of the pitch-based carbon short fiber filler. Further, the surface of the pitch-based carbon fiber filler observed with a scanning electron microscope at a magnification of 4000 times was smooth with no large irregularities.
The crystal size in the thickness direction of the hexagonal network surface determined by the X-ray diffraction method was 15 nm. The crystal size in the growth direction of the hexagonal network surface was 20 nm.

A single yarn was extracted from a graphitized web prepared by the same process up to firing and not milled, and heat-treated at 3000 ° C. in an electric furnace in a non-oxidizing atmosphere, and the electrical resistivity was measured. 2.5 μΩm. The thermal conductivity obtained using the following formula (1) was 460 W / (m · K).
[Equation 2]
K = 1272.4 / ER-49.4 (1)

[Experiment 2]
A pitch made of a condensed polycyclic hydrocarbon compound was used as a main raw material. The optical anisotropy ratio was 100%, and the softening point was 287 ° C. Using a spinneret with a circular hole having a diameter of 0.2 mm, heated air was ejected from the slit at a linear velocity of 6000 m / min, and the pitch was melted to produce pitch fibers having an average fiber diameter of 11 μm. The spun fibers were collected on a belt to form a mat, and then a web made of pitch fibers having a basis weight of 280 g / m ^{2 by} cross wrapping.

  The web was infusibilized by raising the temperature from 175 ° C. to 285 ° C. in air at an average heating rate of 7 ° C./min. The infusible web was fired at 700 ° C. in a nitrogen atmosphere and then milled, and sieved to a short fiber filler having an average fiber length of 30 μm. Then, it graphitized by heat-processing at 3000 degreeC with the electric furnace made into the non-oxidizing atmosphere, and it was set as the pitch-type carbon short fiber filler. The average fiber diameter was 8.1 μm. The percentage of the fiber diameter dispersion to the average fiber diameter was 16%. The true density was 2.13 g / cc. The image was observed with a transmission electron microscope at a magnification of 1,000,000 times and magnified on a photograph at 4 million times. The graphene sheet was closed on the end face of the pitch-based carbon short fiber filler. Further, the surface of the pitch-based carbon short fiber filler, which was observed with a scanning electron microscope at a magnification of 4000 times, was smooth with no large irregularities.

The crystal size in the thickness direction of the hexagonal network surface determined by the X-ray diffraction method was 14 nm. The crystal size in the growth direction of the hexagonal network surface was 28 nm.
A single yarn was extracted from a graphitized web prepared by the same process up to firing and not milled, and heat-treated at 3000 ° C. in an electric furnace in a non-oxidizing atmosphere, and the electrical resistivity was measured. 2.3 μΩm. The thermal conductivity obtained using the above formula (1) was 510 W / (m · K).

[Experiment 3]
By adjusting the opening of sieving after milling with the same web as in Experimental Example 1, a pitch-based carbon short fiber filler having an average fiber length of 350 μm was obtained.
The average fiber diameter was 9.9 μm. The percentage of the fiber diameter dispersion to the average fiber diameter was 16%. The true density was 2.15 g / cc. The image was observed with a transmission electron microscope at a magnification of 1,000,000 times and magnified on a photograph at 4 million times. The graphene sheet was closed on the end face of the pitch-based carbon fiber filler. Further, the surface of the pitch-based carbon short fiber filler, which was observed with a scanning electron microscope at a magnification of 4000 times, was smooth with no large irregularities.

The crystal size in the thickness direction of the hexagonal network surface determined by the X-ray diffraction method was 16 nm. The crystal size in the growth direction of the hexagonal network surface was 21 nm.
The thermal conductivity is the same as that of Experimental Example 1 because the graphitized material is used as it is as the web before milling.

[Experimental Example 4]
By adjusting the opening of sieving after milling with the same web as in Experimental Example 2, a pitch-based carbon short fiber filler having an average fiber length of 400 μm was obtained.
The average fiber diameter was 7.9 μm. The percentage of the fiber diameter dispersion to the average fiber diameter was 15%. The true density was 2.13 g / cc. The image was observed with a transmission electron microscope at a magnification of 1,000,000 times and magnified on a photograph at 4 million times. The graphene sheet was closed on the end face of the pitch-based carbon short fiber filler. Further, the surface of the pitch-based carbon short fiber filler, which was observed with a scanning electron microscope at a magnification of 4000 times, was smooth with no large irregularities.

The crystal size in the thickness direction of the hexagonal network surface determined by the X-ray diffraction method was 15 nm. The crystal size in the growth direction of the hexagonal network surface was 29 nm.
The thermal conductivity is the same as that in Experimental Example 2 because the graphitized material is used as it is as the web before milling.

An outline of a production example of the carbon fiber aggregate is shown below.
In order to reduce the production cost and to obtain a carbon fiber assembly having two types of fiber lengths that are reasonably long and short, pitch fibers are spun under substantially the same conditions using the same pitch raw material. The long fiber here means not a continuous fiber but a fiber having a relatively long average fiber length. The pitch fiber is collected on the wire mesh belt without changing the conditions such as the spinneret, spinning temperature, discharge rate per hour, heated gas temperature / spout speed from the slit, and spout position, and if necessary, cross-wrapping. After adjusting the basis weight, lightly adhering with a binder, adding a rolling press, infusibilizing, further firing, and then shortening this pitch fiber using a milling device, short fiber A Get.

  Next, a carbon fiber aggregate of long fibers and short fibers was prepared. A flat mixed fiber sheet is obtained by blending with pitch-based carbon fibers made of long fibers B previously collected on a wire mesh belt. When adjusting to this sheet, a wet papermaking method in which a water-swellable organic polymer such as polyvinyl alcohol (PVA) fiber is partially used instead of a binder is applied, or short fibers and long fibers are utilized by utilizing the amount of air. A dry papermaking method in which fibers are mixed and fused by interposing a thermoplastic resin instead of a binder can be applied. After that, if necessary, a carbon fiber aggregate for a composite material that can be mixed with a matrix is obtained through various steps such as infusibilization, firing treatment, and graphitization treatment.

[Experimental Example 5]
A pitch made of a condensed polycyclic hydrocarbon compound was used as a main raw material. The main raw material had an optical anisotropy ratio of 100% and a softening point of 285 ° C. A spinneret having a hole diameter of 0.2 mm was used, heated air was ejected from the slit at a linear velocity of 5000 m / min, and the melt pitch was pulled to spin pitch-based long fibers having an average diameter of 11 μm. The spun fibers were collected on a belt to form a mat, further cross-wrapped, and shaped into a pitch fiber sheet having a three-dimensional random shape with a basis weight of 250 g / m ² .

  A part of this pitch fiber sheet is subjected to the following treatment to obtain short carbon fibers. That is, this pitch fiber sheet was infusibilized by raising the temperature from 170 ° C. to 300 ° C. at an average temperature raising rate of 5 ° C./min. The infusible pitch fiber sheet was fired at 900 ° C., then shortened with a pulverizer, and then fired at 3000 ° C. to obtain pitch-based carbon short fibers. The average diameter (D1) of the pitch-based carbon short fibers was 10 μm, and the ratio of the fiber diameter dispersion to D1 (CV1) was 16%. The average fiber length (L1) was 0.5 mm. The crystal size in the thickness direction of the hexagonal mesh surface was 22 nm. The crystal size in the growth direction of the hexagonal network surface was 36 nm. A single yarn was extracted from the mat that had been subjected to the same treatment, and the electrical resistance was measured to find 2.1 μΩm. The thermal conductivity in the fiber axis direction was 530 W / (m · K). The true density of the pitch-based carbon short fibers was 2.18 g / cc.

  In order to make the remaining pitch fiber sheet into carbon long fibers, the infusible pitch fiber sheet was fired and graphitized at 3000 ° C. to obtain a pitch carbon fiber sheet having a three-dimensional random shape. The pitch fiber diameter constituting the pitch-based carbon fiber sheet was 11 μm on average, the variation rate CV was 13%, and the fiber length was 100 mm on average. The crystal size in the thickness direction of the hexagonal mesh surface was 20 nm. The crystal size in the growth direction of the hexagonal network surface was 39 nm, and the thermal conductivity was 530 W / (m · K).

Next, 50 parts by weight of pulverized short carbon fibers were dispersed in a manner of dry blending with respect to 100 parts by weight of the pitch-based carbon fiber sheet and mixed to obtain a pitch-based carbon fiber reinforcing material.
Next, a maleic acid-modified polypropylene film manufactured by Sanyo Kasei Co., Ltd. was used as the matrix resin, and the pitch-based carbon fiber reinforcement was set to 40% as the volume ratio of the molded body. In addition, press molding was performed so that the inner diameter was 1 mm with a 650 mm inner die. When the heat conductivity of the molded carbon fiber composite material was measured, it was 10.5 W / (m · K). The surface resistance was 0.7Ω / □ (Ω / sq.).

[Experimental Example 6]
In Experimental Example 5, SE1740 manufactured by Toray Dow Corning Co., which is a thermosetting silicone resin, was used as the matrix resin. The viscosity of the resin component was 1.1 Pa · S. The pitch-based carbon fiber reinforcement is set to 35% as the volume ratio of the molded body, and press molding is performed with a vacuum press machine manufactured by Kitagawa Seiki Co., Ltd. to a thickness of 0.5 mm with a 300 mm inner die. Carried out. It was 9.5 W / (m * K) when the heat conductivity of the shape | molded carbon fiber composite material was measured. The surface resistance was 10Ω / □ (Ω / sq.).

[Experimental Example 7]
A pitch made of a condensed polycyclic hydrocarbon compound was used as a main raw material. This main raw material had an optical anisotropy ratio of 100% and a softening point of 285 ° C. A spinneret having a hole diameter of 0.2 mm was used, heated air was ejected from the slit at a linear velocity of 4800 m / min, and the melt pitch was pulled to spin pitch fibers having an average diameter of 12 μm. The spun fibers were collected on a belt to form a mat, and further, a pitch fiber mat having a three-dimensional random shape with a basis weight of 250 g / m ² was obtained by cross wrapping.

  This pitch fiber mat was heated in the air from 170 ° C. to 300 ° C. under an average temperature rising rate of 5 ° C./min for infusibilization treatment. The infusible pitch fiber mat was fired and graphitized at 3000 ° C. to obtain a pitch-based carbon fiber sheet having a three-dimensional random shape. The fiber diameter of the pitch-based carbon fibers constituting the pitch-based carbon fiber sheet was 10 μm on average, and the diameter variation rate CV was 19%. The fiber length was 150 mm on average. The crystal size in the thickness direction of the hexagonal mesh surface was 30 nm. The crystal size in the growth direction of the hexagonal network surface was 41 nm. The electric conductivity was 2.0 μΩm, and the thermal conductivity was 590 W / (m · K).

  The pitch fiber mat having been subjected to the infusibilization treatment was fired at 700 ° C., then shortened with a pulverizer, and then further fired and graphitized at 3000 ° C. to obtain carbon fibers. The carbon fiber had an average fiber diameter of 10 μm and a CV of 17%. The average fiber length of these short fibers was 0.2 mm.

  Next, a polycarbonate resin manufactured by Teijin Chemicals Ltd. is used as a matrix resin, 20 parts by weight of carbon fiber is melt-kneaded with 100 parts by weight of the polycarbonate resin using a twin screw extruder equipped with a film forming die, and then a film A molded product was obtained.

  Furthermore, a pitch-based carbon fiber sheet used as a pitch-based carbon fiber reinforcing material using a polycarbonate film containing carbon short fibers B obtained by the above method, a polycarbonate film manufactured by Teijin Chemicals Limited and a pitch-based carbon fiber reinforcing material The weight ratio of carbon fibers to short fibers is 100 parts by weight: 50 parts by weight, and the carbon fiber reinforcement is set to 30% as the volume ratio of the molded body. Using a 650 mm mold, press molding was performed so that the thickness became 1 mm. It was 7.7 W / (m * K) when the heat conductivity of the shape | molded carbon fiber composite material was measured. The surface resistance was 1.9Ω / □ (Ω / sq.).

The carbon fiber composite material of Experimental Examples 5 to 7 prepared using the carbon fiber aggregates obtained in Electrical Insulation Experimental Examples 1 to 4 was subjected to various electrical insulation treatments shown below to obtain carbon fiber composite laminates. Created. And surface resistance and thermal conductivity were measured.

[Example 1]
A thermosetting silicone resin (SE1740 manufactured by Toray Dow Corning Co., Ltd.) diluted to 40 phr with heptane (SE 1740 manufactured by Toray Dow Corning Co., Ltd.) is used on both sides of the carbon fiber composite materials prepared in Experimental Examples 5, 6, and 7. Painted with a Meyer bar. The coating thickness after curing and drying at 130 ° C. for 30 minutes was 18 μm. The surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more for all the carbon fiber composite materials. The thermal conductivities were 9.3, 8.7, and 7.0 W / (m · K), respectively. Although the thermal conductivity slightly decreased, the surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more.

[Example 2]
A thermosetting epoxy resin (Epicoat 871 manufactured by Japan Epoxy Resin Co., Ltd. and a curing agent) diluted to 30 phr with MIBK was applied to both surfaces of the carbon fiber composite materials prepared in Experimental Examples 5, 6, and 7 with a No. 30 Meyer bar. . The coating thickness after curing and drying at 130 ° C. for 30 minutes was 13 μm. The surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more for all the carbon fiber composite materials. The thermal conductivities were 9.0, 8.8, and 6.9 W / (m · K), respectively. Although the thermal conductivity slightly decreased, the surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more.

[Example 3]
Boron nitride (GE Chemical Co., Ltd.) with a volume fraction of 30% in thermosetting silicone resin (SE1740 manufactured by Toray Dow Corning Co., Ltd.) diluted to 40 phr with heptane on both sides of the carbon fiber composite materials prepared in Experimental Examples 5, 6, and 7. The mixture was mixed with a No. 50 Meyer bar. The coating thickness after curing and drying at 130 ° C. for 30 minutes was 20 μm. The surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more for all the carbon fiber composite materials. The thermal conductivities were 9.6, 8.6, and 7.2 W / (m · K), respectively. Although the thermal conductivity slightly decreased, the surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more. In particular, the carbon fiber composite material prepared in Experimental Example 6 maintained high flexibility.

[Example 4]
Boron nitride (GE Chemical Co., Ltd.) with a volume fraction of 30% in thermosetting silicone resin (SE1740 manufactured by Toray Dow Corning Co., Ltd.) diluted to 30 phr with heptane on both sides of the carbon fiber composite materials prepared in Experimental Examples 5, 6, and 7. A liquid prepared by mixing (manufactured by: average particle diameter 1 μm) was formed by a dipping method. The thickness after curing and drying at 130 ° C. for 1 hour was 50 μm. The surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more for all the carbon fiber composite materials. The thermal conductivities were 9.0, 8.1, and 6.7 W / (m · K), respectively. Although the thermal conductivity slightly decreased, the surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more. In particular, the carbon fiber composite material prepared in Experimental Example 6 maintained high flexibility.

[Example 5]
30% volumetric aluminum oxide (electrochemical company) in a thermosetting silicone resin (SE1740 manufactured by Toray Dow Corning Co., Ltd.) diluted to 40 phr with heptane on both sides of the carbon fiber composite materials prepared in Experimental Examples 5, 6, and 7. The mixture was mixed with a No. 50 Meyer bar. The coating thickness after curing and drying at 130 ° C. for 30 minutes was 20 μm. The surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more for all the carbon fiber composite materials. The thermal conductivities were 9.2, 8.1, and 6.8 W / (m · K), respectively. Although the thermal conductivity slightly decreased, the surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more. In particular, the carbon fiber composite material prepared in Experimental Example 6 maintained high flexibility.

[Example 6]
A silicon oxide film having a thickness of 20 nm was formed on both surfaces of the carbon fiber composite materials prepared in Experimental Examples 5, 6, and 7 by sputtering. The surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more for all the carbon fiber composite materials. The thermal conductivities were 10.3, 9.2, and 7.5 W / (m · K), respectively. Although the thermal conductivity slightly decreased, the surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more.

[Example 7]
A 300 nm silicon oxide film was formed by chemical vapor deposition using plasma amplification on both sides of the carbon fiber composite material prepared in Experimental Examples 5, 6, and 7, using alkoxysilane as a raw material. The surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more for all the carbon fiber composite materials. The thermal conductivities were 10.2, 9.1, and 7.3 W / (m · K), respectively. Although the thermal conductivity slightly decreased, the surface resistance was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or more.

[Comparative Example 1]
In Example 1, the thermosetting silicone resin was directly applied with a thickness of 200 μm. Curing and drying were performed at 130 ° C. for 1 hour. Although insulation was achieved, the thermal conductivity was remarkably reduced to 1.4, 0.9, 0.8 W / (m · K), and the thermal conductivity was not sufficient.

[Comparative Example 2]
In Example 6, the sputtering thickness was 2 nm. The thermal conductivity was not changed from 10.5, 9.5, and 7.7 W / (m · K), but the electrical conductivity was 1 × 10 ⁶ Ω / □ (Ω / sq.) Or less.

[Example 8]
When the carbon fiber composite material with electrical insulation provided in Example 1 was pasted on a heating element at 70 ° C., the heat dissipation was improved and it acted as a heat conductive sheet.

[Comparative Example 3]
When the carbon fiber composite material produced in Comparative Example 1 was affixed onto a heating element at 70 ° C., the heat dissipation property deteriorated and did not act as a heat conductive sheet.

[Example 9]
When the radio wave shielding capability of the carbon fiber composite material with electrical insulation provided in Example 1 was examined in the near field with respect to a frequency of 3 GHz, it was found that the radio wave shielding ability was present.

Claims (20)

  A composition comprising a matrix and a thermally conductive carbon fiber aggregate, wherein the matrix exhibits electrical insulation, and the carbon fiber aggregate is electrically insulated by covering the entire surface including its end face with the matrix. Carbon fiber composite material capable of forming a layer.   A composition comprising a matrix and a thermally conductive carbon fiber aggregate, wherein the matrix exhibits electrical insulation, and the carbon fiber aggregate comprises pitch-based carbon fibers having different fiber diameters and / or fiber lengths. The carbon fiber composite material according to claim 1, which has a composition having a high carbon fiber filling rate when combined with a matrix.   The carbon fiber aggregate according to claim 1 is composed of a pitch-based carbon fiber filler having a substantially flat observation surface by a scanning electron microscope, and an average fiber diameter (D1) observed by an optical microscope is in a range of 5 μm to 20 μm. The percentage of the average fiber diameter dispersion (S1) with respect to the average fiber diameter (D1) is 5 to 18%, the end face of the carbon fiber filler is closed, and the average fiber length (L1) is 10 μm to 700 μm. The carbon fiber composite material according to claim 1, wherein the aspect ratio of L1 to D1 is in the range of 1 to 100.   The pitch-based carbon according to claim 3, wherein the true density of the pitch-based carbon fiber filler is in the range of 1.5 to 2.2 g / cc, and the thermal conductivity in the fiber axis direction is 300 W / (m · K) or more. Carbon fiber composite material containing fiber filler.   The carbon fiber composite containing the pitch-based carbon fiber filler according to claim 3 or 4, wherein the crystal size in the thickness direction of the hexagonal network surface is 10 nm or more and the crystal size in the growth direction of the hexagonal network surface is 8 nm or more. material.   The carbon fiber composite material according to claim 1, which is a composition comprising a carbon fiber aggregate and a matrix, wherein the carbon fiber aggregate is contained in a volume fraction of 3 to 60% by volume with respect to the matrix.   The carbon fiber composite material according to claim 5, comprising a thermoplastic resin and / or a thermosetting resin as a matrix.   The thermoplastic resin includes at least one resin selected from the group consisting of polycarbonates, polyethylene terephthalates, polyethylene 2,6 naphthalates, nylons, polypropylenes, polyethylenes, polyepoxy ether ketones, and polyphenylene sulfides. 8. The carbon fiber composite material according to 7.   The carbon fiber composite material according to claim 7, comprising at least one resin selected from the group of epoxies, acrylics, urethanes, silicones, and phenols as the thermosetting resin.   An electrically insulating layer comprising a metal oxide thin film, an inorganic polymer coating film, or an organic polymer coating film on the surface of a molded product formed by molding the carbon fiber composite material according to any one of claims 7 to 9. A carbon fiber composite laminate formed by forming   An oxide and / or nitride of a metal selected from the group consisting of aluminum, silicon, boron, and zinc on the surface of a molded product formed by molding the carbon fiber composite material according to any one of claims 7 to 9. And / or a carbon fiber composite laminate formed by forming an electrical insulating layer comprising a coating film of an organic polymer containing fine particles of oxynitride and / or carbide.   A carbon fiber composite laminate obtained by laminating a molded product obtained by molding the carbon fiber composite material according to claim 7 and an electrical insulating layer.   13. The carbon fiber composite laminate according to claim 10, wherein the molded product in a state of being formed into a flat plate has a thermal conductivity of 2 W / (m · K) or more.   The surface of the molded product formed by molding a heat conductive carbon fiber composite material including a carbon fiber aggregate and a matrix is electrically insulated by electroless plating, electrolytic plating, vacuum deposition, sputtering or ion plating. The processing method of the carbon fiber composite molded product according to claim 10, wherein a metal oxide or a ceramic is deposited.   Chemical vapor deposition method, coating, dipping, or mechanochemical method of mechanically fixing fine particles to the surface of a molded product formed by molding a thermally conductive carbon fiber composite material containing a carbon fiber aggregate and a matrix The method for processing a carbon fiber composite molded article according to claim 10, wherein the metal or ceramic is coated by the method.   Any one selected from the group consisting of a dipping method, a Meyer bar method, a gravure method, a micro gravure method, and an extrusion method on the surface of a molded product formed by molding a thermally conductive carbon fiber composite material including a carbon fiber aggregate and a matrix. The method for processing a carbon fiber composite molded article according to claim 11, wherein lamination is performed by any method.   The composite molding material according to any one of claims 6 to 9, at least selected from the group consisting of an injection molding method, a press molding method, a calendar molding method, a roll molding method, an extrusion molding method, a casting molding method, and a blow molding method. A method for producing a carbon fiber composite molded article molded by one type of molding means.   The heat radiating member for electronic components which uses the carbon fiber composite molding in any one of Claims 6-12 as a main material.   The electromagnetic wave shielding board which uses the carbon fiber composite molding in any one of Claims 6-12 as a main material.   The heat exchanger which uses as a main material the carbon fiber composite molding in any one of Claims 6-12.