JP2008163535A - Carbon fiber composite structure and method for producing the carbon fiber composite structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon fiber composite structure requiring no process of giving the carbon fiber a three-dimensional structure when producing a composite material. <P>SOLUTION: The carbon fiber composite structure can be produced by a first process, in which a carbon material is grown to be fibrous while the carbon material is grown in the circumferential direction of a catalyst particle to be used so as to obtain an intermediate of carbon fiber structure of three-dimensional network by using at least two or more carbon compounds having different decomposition temperature as a carbon source when heating the catalyst and a hydrocarbon mixture gas at a constant temperature of 800°C-1300°C, a second process, in which the obtained intermediate of the carbon fiber structure is soaked in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant, and then the used solvent is dried, and a third process, in which the intermediate of the carbon fiber composite is heated at 800°C-1,200°C after drying, and then annealed at 1,800°C-3,000°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fine carbon fiber structure, and more particularly to a carbon fiber structure whose surface is modified by having metal fine particles and / or metal carbide fine particles on the surface of the carbon fiber structure.

  Since carbon fibers have excellent mechanical properties and high electrical conductivity, they are used as filler materials in composite materials such as synthetic resins, rubber, ceramics, and metals. In particular, it has been reported that the mechanical strength, electrical conductivity, and thermal conductivity are improved by making the carbon fiber aggregate into a three-dimensional structure. For example, carbon fiber aggregates, in which carbon fibers are heat-treated at 600 ° C. or higher and the contact points of the intertwined fibers are bonded and fixed by carbides such as tar and pitch, are added to the matrix to improve conductivity and thermal conductivity. An improved composite material has been obtained (see, for example, Patent Document 1). In addition, a composition containing a fibrous carbonaceous material, a thermosetting resin, and an easily graphitizable material is heated to a temperature lower than the temperature at which the easily graphitizable material graphitizes to form a molded body, and the molded body is further fired. A sintered body with improved mechanical strength is obtained. In this case, when the graphitizable material is graphitized by the firing process, the fibrous carbonaceous materials are joined to each other (for example, see Patent Document 2).

  Furthermore, as for the three-dimensional structure of the carbon fiber aggregate, synthetic resin, rubber, metal, and carbon-based materials can be selected as impregnation materials, and nano-carbon composite materials with a wide application range have been reported. Carbon nanotubes and thermosetting resin are kneaded, dried, and molded at a predetermined pressure and a predetermined temperature. This molded body is heated to carbonize the resin, and the nanocarbon is three-dimensionally connected with carbon. A porous material is obtained. A nanocarbon composite material is obtained by impregnating various impregnating materials after the carbonization step (see, for example, Patent Document 3).

  In the above example, by giving a three-dimensional structure to the carbon fiber, the thermal conductivity, conductivity, and mechanical strength of the finally obtained composite material are improved. However, in these reports, for example, the importance of adhesion between synthetic resin, rubber, ceramics, metal, and carbon nanotube, which are impregnated materials, is not mentioned.

  About the composite material containing a carbon nanotube, the following is pointed out (refer nonpatent literature 1). That is, what is important in developing the mechanical strength is the adhesive strength between the CNT and the matrix material. The matrix material may be metal, ceramic, polymer, carbon, etc., but it is estimated that the surface structure with few defects of CNT works in the direction of worsening the wettability with the matrix metal normally used in composite materials for structural materials. In order to obtain a composite material with high strength, it is necessary to modify the CNT surface or devise a method for adjusting the composite material.

  Further, it is generally known that the interface structure in the carbon fiber composite material has a significant influence on the performance of the composite material, and that the control of the interface structure is important (see Non-Patent Document 2).

  A method for modifying a carbon fiber for a composite material in which the surface of the carbon fiber is coated with a metal has been reported (for example, see Patent Document 4). In this document, for the purpose of improving the interlaminar shear strength between the matrix material and the carbon fiber, a film is formed on the surface of the carbon fiber with a solution of titanium alkoxides, and the film is heated to 130 to 150 ° C. and 280 to 300 ° C. Example 1), a titanium oxide film is formed. This film improves the adhesion between the matrix material and the carbon fibers and improves the interlaminar shear strength.

  In addition, it has been reported that metal-coated carbon nanotubes are obtained by chemically reacting with carbon nanotubes to introduce functional groups on the tube surface, and contact with a metal salt solution to perform ion exchange (for example, patents). Reference 5). The metal-coated carbon nanotubes are described as being usable as an intermediate material between carbon nanotubes and metal composites, and are not subjected to any post-treatment particularly at high temperatures. Anxiety remains.

  Further, by pressurizing and sintering a plurality of carbon nanotubes, carbide forming metal and matrix metal at a temperature equal to or higher than the melting point of the matrix metal, a metal carbide is formed on the surface of the plurality of carbon nanotubes. It has been reported that a highly heat-conductive heat dissipating material that can obtain good adhesion between the two is manufactured (for example, see Patent Document 6). In this case, the metal carbide coats the carbon nanotube aggregate (multiple carbon nanotubes), and furthermore, different metals from both the metal matrix and the metal carbide source of different metal species must be charged at the same time. Only it is limited to some metals.

  As described above, by imparting a three-dimensional structure to the carbon fiber, the sintered body and the nanocarbon composite material have improved thermal conductivity, conductivity, and mechanical strength. This three-dimensional structure of the carbon fiber is obtained by adding later, and is not a reaction-generated three-dimensional network-like carbon fiber structure. In addition, the carbon fiber for composite materials in which the surface of the carbon fiber reported above is covered with a metal has no example of adopting a three-dimensional network-like carbon fiber structure.

On the other hand, a report on a three-dimensional network-like carbon fiber structure has also been made (see, for example, Patent Document 7). It is a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm, and the carbon fiber structure is a mode in which a plurality of carbon fibers extend, and the carbon fiber structure is more than the outer diameter of the carbon fiber. The carbon fiber structure is a carbon fiber structure having a large particle size and a granular portion for bonding the carbon fibers to each other, and the granular portion is formed in the growth process of the carbon fiber. There has been no report on surface processing technology.
JP 2004-119386 A JP 2005-178151 A JP 2004-315297 A Japanese Patent Publication No. 63-60152 Japanese Patent No. 2953996 JP 2004-10978 A Japanese Patent No. 3776111 “Carbon Nanotube” Chemistry, 2001, p. 115 “Composite Materials and Interfaces—High Functionalization and Control of Materials” Materials Technology Research Association, 1988, p. 251

  As described above, in order to improve the thermal conductivity, conductivity, and mechanical strength of the finally obtained composite material, it is required to impart a three-dimensional structure to the carbon fiber. When a process for imparting a three-dimensional structure to the carbon fiber later is required at the stage of manufacturing the carbon fiber, various restrictions are imposed on the production of the composite material, and the three-dimensional structure is imparted. It becomes necessary to add a process. On the other hand, in the case of metal coating on the surface of carbon nanotubes, in a method in which post-treatment is not performed at a high temperature, since it depends only on the physical bonding force, the metal coating remains uneasy in terms of strength. In addition, the method of chemically reacting with carbon nanotubes to introduce functional groups on the tube surface and metallizing the carbon nanotube surface may cause a bad influence on the structure of the carbon nanotubes. The effect of improving the performance is not sufficiently obtained. By pressing and sintering a plurality of carbon nanotubes, carbide forming metal and matrix metal at a temperature equal to or higher than the melting point of the matrix metal, metal carbide is formed on the surface of the plurality of carbon nanotubes, and between the matrix metal and the carbon nanotube. In a method for obtaining good adhesion, a metal matrix and a different metal from a metal carbide source must be charged at the same time, and the matrix material is limited to some metals. Further, in covering the aggregate of carbon nanotubes, the surface structure of the carbon nanotubes is not modified, the wettability with the matrix metal is not improved, and a device is required for adhesion to the matrix material. Moreover, since the dispersion in the matrix material becomes a problem by covering the aggregates of carbon nanotubes, it is difficult to expand to application ranges other than metals such as synthetic resins, rubber, ceramics, and carbon-based materials.

  The present invention does not require a step for imparting a three-dimensional structure to carbon fibers when producing a composite material, and the metal fine particles and / or metal carbide fine particles are formed on the surface of the carbon nanotubes having a surface structure with few defects. It is an object of the present invention to provide a three-dimensional network-like carbon fiber composite structure having a strong bonding force between metal fine particles and / or metal carbide fine particles and carbon nanotubes by post-treatment at a high temperature.

  As a result of continuing intensive studies on the above problems, the present inventors have found that a specific organometallic compound forms metal carbide fine particles of a metal corresponding to the surface of a carbon nanotube at a high temperature, thereby completing the present invention. It came to.

  That is, the present invention is a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm, wherein the carbon fiber structure is a mode in which a plurality of carbon fibers extend, A carbon fiber structure having a granular part larger than the outer diameter and bonding the carbon fibers to each other, and the granular part formed in the growth process of the carbon fiber, A carbon fiber composite structure characterized in that the surface contains fine particles of metal and / or metal carbide.

  In the present invention, the carbon fiber structure described above contains fine particles of metal and / or metal carbide on the surface thereof to form a carbon fiber composite structure, and the carbon fiber composite structure is hot-pressed and carbonized. It is the preform of the carbon fiber composite structure obtained through the process.

  Furthermore, in the present invention, when the mixed gas of the catalyst and the hydrocarbon is heated at a constant temperature of 800 ° C. to 1300 ° C., by using at least two carbon compounds having different decomposition temperatures as a carbon source, First step of obtaining a three-dimensional network-like carbon fiber structure intermediate by growing in the circumferential direction of the catalyst particles to be used while growing in a fibrous form, the intermediate of the obtained carbon fiber structure Is immersed in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant, and then the second solvent is dried. After drying, the intermediate of the carbon fiber structure is heated to 800 ° C. to 1200 ° C. Then, a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm, comprising a third step of annealing at 1800 ° C. to 3000 ° C., The carbon fiber structure is a mode in which a plurality of carbon fibers extend, and has a granular portion that has a larger particle diameter than the outer diameter of the carbon fiber and bonds the carbon fibers to each other, and the granular portion is A method for producing a carbon fiber composite structure, characterized in that the carbon fiber structure formed in the carbon fiber growth process contains fine particles of metal and / or metal carbide on the surface thereof. (See FIG. 1).

  Further, in the method for producing a preform of a carbon fiber composite structure according to the present invention, a binder is added to a carbon fiber composite structure containing fine particles of metal and / or metal carbide on the surface thereof, and 100 ° C. It is characterized by producing a preform of carbon fiber composite structure by hot pressing at ~ 200 ° C and then carbonizing at 800 ° C to 1200 ° C (see Fig. 1).

  In the method for producing a carbon fiber composite structure of the present invention, the annealing process is performed in the third step, and if necessary, the carbon fiber structure obtained in the first step is interposed between the first step and the second step. A preliminary annealing step can be added to heat the intermediate to 800 ° C to 1200 ° C.

The present invention also shows the carbon fiber composite structure, wherein I _D / I _G measured by Raman spectroscopy is 0.2 or less.

  The present invention further shows the carbon fiber composite structure in which the content of fine particles of metal and / or metal carbide is 1 to 200% by mass in terms of metal with respect to the carbon fiber structure.

  The present invention further shows the carbon fiber composite structure in which the surface coverage of the carbon fiber structure by the metal and / or metal carbide fine particles is 1 to 100%, preferably 10 to 100%. is there. In addition, this surface coverage is the value calculated | required by image-analyzing the electron micrograph of the obtained carbon fiber composite structure surface.

  The present invention also shows the carbon fiber composite structure in which the size of the fine particles of metal and / or metal carbide is 1 to 70 nm, preferably 1 to 60 nm. The size of the metal and / or metal carbide fine particles in this case is represented by the horizontal length of the portion where the fine particles are in contact with the carbon fiber structure.

  Further, as the metal species used for the fine particles of metal and / or metal carbide formed on the surface of the carbon fiber structure of the present invention, Ti, V, Cr, Zr, Nb, Mo, Ta, W, One or more selected from Y.

  Moreover, this invention shows the said carbon fiber composite structure containing 0.001-30 mass% in conversion of boron with respect to a carbon fiber composite structure, Preferably 0.01-3.0 mass% boron compound is shown. Is.

  The present invention provides a carbon fiber composite wherein when the organometallic compound is used in the second step of the method for producing the carbon fiber composite structure, the organometallic compound is a metal alkoxide, a metal acetylacetonate, or a metal fatty acid salt. The manufacturing method of a structure is shown.

  Furthermore, the present invention provides an organic solvent solution of a boron compound or an organic solvent solution of a boron compound or an aqueous solution of a metal salt and a surfactant in the second step of the method for producing the carbon fiber composite structure. A method for producing a carbon fiber composite structure characterized by containing 0.001 to 30% by mass of a boron compound in terms of boron to the carbon fiber composite structure described above by mixing an aqueous solution. is there.

  Since the carbon fiber composite structure of the present invention is formed in a three-dimensional network shape, when the composite material is finally manufactured, its thermal conductivity, conductivity, and mechanical strength are good. Moreover, the process for providing a three-dimensional structure later is unnecessary. Since the carbon and / or metal carbide fine particles on the surface of the carbon fiber composite structure of the present invention do not have a bad influence on the structure of the carbon nanotube, the physical properties of the carbon nanotube may be deteriorated by surface modification. No. In the finally produced composite material, the adhesion between the carbon fiber composite structure and the matrix is improved, and it becomes strong due to the anchor effect (see FIG. 2). The fine metal particles on the surface of the carbon fiber composite structure act as a graphitization catalyst for the carbon compound. In the carbon fiber composite structure of the present invention, metals, ceramics other than metals, rubber, synthetic resins, carbon-based materials, and the like can be used as matrix materials.

Hereinafter, the present invention will be described in detail based on embodiments.
(Carbon fiber composite structure)
First, the carbon fiber composite structure according to the present invention will be described.

  The carbon fiber composite structure according to the present invention is a three-dimensional network-like carbon fiber structure composed of carbon fibers having a carbon fiber composite structure outer diameter of 15 to 100 nm, and the carbon fiber structure includes a plurality of carbon fibers. In an extended manner, the carbon fiber has a granular part larger than the outer diameter of the carbon fiber and bonded to the carbon fiber, and the granular part is formed in the process of growing the carbon fiber. The carbon fiber structure is a carbon fiber composite structure characterized in that the surface thereof contains fine particles of metal and / or metal carbide.

  In the carbon fiber composite structure according to the present invention, the outer diameter of the carbon fiber constituting the three-dimensional network-like carbon fiber structure forming the basic skeleton is in the range of 15 to 100 nm. If it is less than the number, the cross section of the carbon fiber does not have a polygonal shape as will be described later. On the other hand, as the diameter of the carbon fiber decreases, the number per unit amount increases and the length of the carbon fiber in the axial direction also increases. In order to obtain high conductivity, the outer diameter exceeding 100 nm is not suitable as a carbon fiber structure disposed as a modifier or additive in a matrix such as a resin. The outer diameter of the carbon fiber is particularly preferably in the range of 20 to 70 nm. In this outer diameter range, a cylindrical graphene sheet laminated in a direction perpendicular to the axis, that is, a multilayer, is not easily bent, and is elastic, that is, has the property of returning to its original shape even after deformation. Therefore, even after the carbon fiber structure is once compressed, it is easy to adopt a sparse structure after being arranged in a matrix such as a resin.

  In addition, it is desirable that the fine carbon fiber has an outer diameter that changes along the axial direction. If the outer diameter of the carbon fiber is not constant along the axial direction and varies, it is considered that a kind of anchoring effect occurs in the carbon fiber in the matrix such as resin, and the movement in the matrix Is less likely to occur and the dispersion stability is increased.

  Furthermore, in this carbon fiber structure, fine carbon fibers having such a predetermined outer diameter exist in a three-dimensional network, but these carbon fibers are bonded to each other in the granular portion formed during the growth process of the carbon fibers. And a shape in which a plurality of the carbon fibers extend from the granular portion. In this way, the fine carbon fibers are not simply entangled with each other, but are firmly bonded to each other in the granular portion, so that when the structure is disposed in a matrix such as a resin, the structure is Without being disperse | distributed as a carbon fiber single-piece | unit, it can be disperse-blended in a matrix with a bulky structure. Further, in the carbon fiber structure according to the present invention, since the carbon fibers are bonded to each other by the granular part formed in the growth process of the carbon fiber, the electrical characteristics of the structure itself are also very high. For example, the electrical resistance value measured at a constant compression density is such that a simple entangled body of fine carbon fibers or a joint point between fine carbon fibers is adhered by a carbonaceous material or a carbide thereof after the carbon fiber is synthesized. Compared with the value of the structure or the like, it shows a very low value, and when it is dispersed and blended in the matrix, a good conductive path can be formed.

Since the granular part is formed in the growth process of the carbon fiber as described above, the carbon-carbon bond in the granular part is sufficiently developed and includes a mixed state of sp ² bond and sp ³ bond. I think that the. And after the generation (intermediate and first intermediate described later), the granular part and the fiber part are continuous with a structure in which patch-like sheet pieces made of carbon atoms are bonded together, and thereafter After the high temperature heat treatment, at least a part of the graphene layer constituting the granular part is continuous with the graphene layer constituting the fine carbon fiber extending from the granular part. In the carbon fiber structure, between the granular portion and the fine carbon fiber, it is symbolized that the graphene layer constituting the granular portion as described above is continuous with the graphene layer constituting the fine carbon fiber. These are connected by carbon crystal structural bonds (at least a part thereof), whereby a strong bond between the granular portion and the fine carbon fiber is formed.

  In the present specification, the term “extending” the carbon fiber from the granular part simply means that the granular part and the carbon fiber are apparently connected by other binder (including carbonaceous material). It does not indicate such a state, but mainly means a state in which they are connected by carbon crystal structural bonds as described above.

  The particle size of the granular part is desirably larger than the outer diameter of the fine carbon fiber. Specifically, for example, the outer diameter of the fine carbon fiber is 1.3 to 250 times, more preferably 1.5 to 100 times, and still more preferably 2.0 to 25 times. In addition, the said value is an average value. Thus, when the particle diameter of the granular part which is a bonding point between carbon fibers is sufficiently large as 1.3 times or more of the outer diameter of the fine carbon fiber, it is higher than the carbon fiber extending from the granular part. When a carbon fiber structure is arranged in a matrix such as a resin due to a bonding force, even if a certain amount of elasticity is applied, the three-dimensional network structure is maintained and dispersed in the matrix. be able to. On the other hand, if the size of the granular part is extremely large exceeding 250 times the outer diameter of the fine carbon fiber, the fibrous properties of the carbon fiber structure may be impaired, for example, into various matrices. This is not desirable because it may not be suitable as an additive or compounding agent. The “particle size of the granular part” in the present specification is a value measured by regarding the granular part, which is a bonding point between carbon fibers, as one particle.

  The specific particle size of the granular part depends on the size of the carbon fiber structure and the outer diameter of the fine carbon fiber in the carbon fiber structure, but for example, an average value of 20 to 5000 nm, more preferably It is about 25 to 2000 nm, more preferably about 30 to 500 nm.

  Furthermore, since this granular part is formed in the growth process of the carbon fiber as described above, it has a relatively spherical shape, and the circularity is 0.2 to <1 on average. , Preferably 0.5 to 0.99, more preferably about 0.7 to 0.98.

  In addition, the granular portion is formed in the carbon fiber growth process as described above, and, for example, the joining point between the fine carbon fibers is adhered by the carbonaceous material or the carbide after the carbon fiber synthesis. Compared with the structure, etc., the bonds between the carbon fibers in the granular part are very strong, and even under conditions where the carbon fiber breaks in the carbon fiber structure, the granular part (Coupling part) is held stably.

  The carbon fiber structure according to the present invention desirably has an area-based circle-equivalent mean diameter of 50 to 1000 μm, preferably 50 to 500 μm, more preferably about 60 to 250 μm. Here, the area-based circle-equivalent mean diameter is obtained by photographing the outer shape of the carbon fiber structure using an electron microscope or the like, and in this photographed image, the contour of each carbon fiber structure is represented by an appropriate image analysis software such as WinRoof. (Trade name, manufactured by Mitani Shoji Co., Ltd.) is used to determine the area within the contour, calculate the equivalent circle diameter of each fiber structure, and average it.

  Since it depends on the type of matrix material such as resin to be compounded, it is not applied in all cases, but when applied to a preform, the one with a larger equivalent circle average diameter is more conductive, This is preferable for mechanical properties and thermal properties, but if it exceeds 1000 μm, the distribution of the carbon fiber structure in the preform becomes inhomogeneous, and the above properties cannot be obtained. When blended in a matrix such as the above, it becomes a factor for determining the longest length of the carbon fiber structure. In general, when the equivalent circle average diameter is less than 50 μm, the conductivity may not be sufficiently exhibited. There is.

  In addition, as described above, the carbon fiber structure according to the present invention includes a carbon fiber structure according to the present invention in which carbon fibers existing in a three-dimensional network are bonded to each other in a granular part, and the carbon fiber Presents a plurality of extending shapes, but in one carbon fiber structure, when there are a plurality of granular parts that combine carbon fibers to form a three-dimensional network, the average between adjacent granular parts The distance is, for example, about 0.5 μm to 300 μm, more preferably 0.5 to 100 μm, and still more preferably about 1 to 50 μm. In addition, the distance between this adjacent granule part measures the distance from the center part of one granular material to the center part of the granule part adjacent to this. When the average distance between the granular materials is less than 0.5 μm, the carbon fiber does not sufficiently develop into a three-dimensional network. For example, when dispersed in a matrix, a good conductive path can be obtained. On the other hand, if the average distance exceeds 300 μm, it becomes a factor of increasing the viscosity when dispersed in the matrix, and the dispersibility of the carbon fiber structure in the matrix This is because there is a risk of lowering.

Furthermore, as described above, the carbon fiber structure according to the present invention has a shape in which carbon fibers existing in a three-dimensional network are bonded to each other in the granular portion, and a plurality of the carbon fibers extend from the granular portion. Therefore, the structure has a bulky structure in which carbon fibers are sparsely present. Specifically, for example, the bulk density is 0.0001 to 0.05 g / cm ³ , more preferably 0.001. It is desirable that it is ˜0.02 g / cm ³ . This is because if the bulk density exceeds 0.05 g / cm ³ , it becomes difficult to improve the physical properties of the matrix such as a resin by adding a small amount.

  Thus, the carbon fiber composite structure of the present invention comprises metal and / or metal carbide fine particles on the surface of the carbon fiber structure constituting the basic skeleton as described above.

  The content of fine particles of metal and / or metal carbide in the carbon fiber composite structure of the present invention is not particularly limited, but is, for example, 1 to 200 mass in terms of metal with respect to the carbon fiber structure. %, More preferably 2 to 100% by mass. When the content of fine particles of metal and / or metal carbide is less than 1% by mass, for example, wettability between carbon fiber and matrix, interfacial adhesion by including such fine particles of metal and / or metal carbide. There is a possibility that the effect of modifying the characteristics such as the situation may not be sufficient. On the other hand, if the content exceeds 200% by mass, fine particles of metal and / or metal carbide are removed from the surface of the carbon fiber structure. This is because there is a possibility that the physical properties of the carbon fiber cannot be used due to an increase in the adhesion amount of the fine particles. Moreover, it is not desirable from the viewpoint of cost to add more metal than necessary.

  The size of the metal and / or metal carbide fine particles is not particularly limited, but is, for example, 1 to 70 nm, preferably 1 to 60 nm. In this case, the size of the metal and / or metal carbide fine particles is represented by the horizontal length of the portion where the fine particles are in contact with the carbon fiber structure. If the size of the fine particles exceeds 70 nm, it is difficult to stably fix the fine particles to the surface of the carbon fiber structure, and there is a possibility that the fine particles are likely to fall off.

  Further, although not particularly limited, the surface coverage of the carbon fiber structure by the metal and / or metal carbide fine particles is, for example, 1 to 100%, preferably 2 to 100%. desirable. The surface coverage is determined by image analysis of an electron micrograph of the obtained carbon fiber composite structure surface. Specifically, the values shown in the present specification are values obtained by the measurement methods shown in Examples described later. When the surface coverage of the carbon fiber structure by the fine particles of metal and / or metal carbide is less than 1%, for example, carbon fibers and a matrix by containing such fine particles of metal and / or metal carbide. There is a risk that the effect of improving the properties such as wettability and interfacial adhesion status may not be sufficient, while the surface coverage does not exceed 100%.

  Furthermore, when the carbon fiber composite structure is arranged in a matrix, the surface coating of the carbon fiber structure is performed in order to obtain a composite material that gives a higher anchoring effect and is particularly excellent in terms of mechanical properties. It is desirable that the rate is about 1 to 70%, particularly about 2 to 50%. On the other hand, when the carbon fiber composite structure is arranged in a matrix, the surface coverage of the carbon fiber structure is about 50 to 100% in order to obtain a particularly excellent composite material in terms of higher heat conduction characteristics and the like. In particular, it is desirable to be about 70 to 100%.

  As the metal species used for the fine particles of the metal and / or metal carbide formed on the surface of the carbon fiber structure of the present invention, various types can be used depending on the properties to be added. As a seed | species, it is 1 type, or 2 or more types selected from Ti, V, Cr, Zr, Nb, Mo, Ta, W, and Y.

  In the carbon fiber composite structure of the present invention, the metal and / or metal carbide fine particles that the carbon fiber composite structure has on the surface thereof partially enter the surface of the carbon fiber, and the crystal structure is integrated. Therefore, the connection with the carbon fiber is strong. For example, as shown in the examples described later, the carbon fiber composite structure is dispersed in a liquid medium, and ultrasonic waves having a predetermined output and a predetermined frequency are applied to the carbon fiber composite structure, thereby adhering metal and / or metal carbide fine particles. The removal of the metal and / or metal carbide fine particles after treatment was found to be less than 10%, more preferably less than 5%, and the metal and / or metal carbide fine particles were a carbon fiber structure. It can be seen that it is firmly fixed to the surface.

  In addition, since the fine particles form convex portions on the surface of the carbon fiber, in the composite material finally produced using the carbon fiber composite structure according to the present invention, the carbon fiber composite structure and the matrix The adhesion situation is improved and it becomes stronger due to the anchor effect. FIG. 2 is a drawing schematically showing this action. As shown in FIG. 2 (a), when a general carbon fiber is blended in the matrix as a filler, the surface of the filler is relatively smooth. Therefore, when strain stress is applied in the interface direction with the matrix, the matrix and Deviation occurs relatively easily with the filler. On the other hand, when the carbon fiber composite structure according to the present invention is used, as described above, since the filler surface has convex portions of the fine particles, as shown in FIG. 2 (b), this is a matrix at the interface with the matrix. Even when a strain stress is applied in the direction of the interface with the matrix, it appears that the matrix and the filler are not easily displaced.

  In addition, the metal and / or metal carbide fine particles on the surface of the carbon fiber composite structure of the present invention do not have a bad influence on the structure of the carbon fiber, so the physical properties of the carbon fiber are deteriorated by surface modification. There is no fear. Moreover, the fine metal particles that the carbon fiber composite structure has on its surface act as a graphitization catalyst for the carbon compound.

  The carbon fiber composite structure of the present invention comprises carbon and fine particles of metal carbide on the surface of the carbon fiber structure constituting the basic skeleton as described above, and the carbon fiber constituting the basic skeleton. The structure has a three-dimensional network structure, and the network structure is not merely entangled between the fine carbon fibers, but has a granular portion that firmly bonds the fine carbon fibers. When a composite material is manufactured, the thermal conductivity, conductivity, and mechanical strength of the composite material are good. Further, there is no need to add a process for providing a three-dimensional structure.

In addition, the carbon fiber composite structure according to the present invention desirably has an _ID / _IG ratio measured by Raman spectroscopy of 0.2 or less, more preferably 0.1 or less. Here, in the Raman spectroscopic analysis, only a peak (G band) near 1580 cm ⁻¹ appears in large single crystal graphite. A peak (D band) appears in the vicinity of 1360 cm ⁻¹ due to the crystal having a finite minute size or lattice defects. For this reason, the smaller the intensity ratio of D band and G band (R = I ₁₃₆₀ / I ₁₅₈₀ = I _D / I _G ), the smaller the amount of defects in the graphene sheet constituting the carbon fiber composite structure. This is because the carbon fiber composite structure according to the present invention can exhibit higher strength and conductivity when the I _D / I _G ratio is the above-mentioned predetermined value.

  The carbon fiber composite structure according to the present invention also desirably has a combustion start temperature in air of 700 ° C. or higher, preferably 750 ° C. or higher, more preferably 800 to 900 ° C. As described above, since the carbon fiber structure has few defects, it has such a high thermal stability.

  Furthermore, in one preferable embodiment of the carbon fiber composite structure of the present invention, 0.001 to 30% by mass, preferably 0.01 to 3.0% by mass of boron in terms of boron with respect to the carbon fiber composite structure. A compound can also be contained. In this case, the site where the boron compound is present in the carbon fiber composite structure and the type of compound of the boron compound are not particularly limited. By the presence of the boron compound in the carbon fiber composite structure, high conductivity can be obtained even when the structure includes some defects.

(Method for producing carbon fiber composite structure)
Next, a method for producing the carbon fiber composite structure according to the present invention as described above will be described.
FIG. 1 is a chart schematically showing the order of steps in a method for producing a carbon fiber composite structure and a method for producing a preform of a carbon fiber composite structure according to the present invention.

  The carbon fiber composite structure according to the present invention is not particularly limited, but basically, when the mixed gas of the catalyst and the hydrocarbon is heated at a constant temperature of 800 ° C. to 1300 ° C., as a carbon source. By using at least two or more carbon compounds having different decomposition temperatures, the carbon material is grown in the form of fibers, while growing in the circumferential direction of the catalyst particles to be used, so that a three-dimensional network-like carbon fiber structure is obtained. A first step of obtaining an intermediate of the body, the intermediate of the obtained carbon fiber structure is immersed in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant, and then the used solvent is dried. The carbon fiber structure intermediate can be heated to 800 ° C. to 1200 ° C. after the second step and dried, and then subjected to a third step of annealing at 1800 ° C. to 3000 ° C. to produce the intermediate. In FIG. 1, the flow in the order of the arrows on the left side of the drawing, that is, “carbon fiber structure formation”, “drying after immersion in a metal solvent solution”, “annealing”, and “carbon fiber composite structure powder” Is the basic procedure of the method for producing a carbon fiber composite structure according to the present invention.

  First, the 1st process of obtaining the intermediate body of a three-dimensional network-like carbon fiber structure is demonstrated. In this first step, basically, a carbon fiber structure (intermediate body) is formed by chemically pyrolyzing an organic compound such as a hydrocarbon by a CVD method using transition metal ultrafine particles as a catalyst.

  As the raw material organic compound, hydrocarbons such as benzene, toluene and xylene, alcohols such as carbon monoxide and ethanol can be used. Although not particularly limited, in order to obtain an intermediate of the carbon fiber structure, it is preferable to use at least two or more carbon compounds having different decomposition temperatures as the carbon source. In this specification, “at least two or more carbon compounds” do not necessarily mean that two or more kinds of raw material organic compounds are used, but one kind of raw material organic compound is used. However, in the process of synthesizing the fiber structure, for example, a reaction such as hydrodealkylation of toluene or xylene occurs, and in the subsequent thermal decomposition reaction system, two decomposition temperatures are different. The aspect which becomes the above carbon compound is also included.

  In addition, when two or more types of carbon compounds are present as carbon sources in the thermal decomposition reaction system, the decomposition temperature of each carbon compound is not limited to the type of the carbon compound, but the carbon compound in the raw material gas. Since it varies depending on the gas partial pressure or molar ratio, a relatively large number of combinations can be used as carbon compounds by adjusting the composition ratio of two or more carbon compounds in the raw material gas.

  For example, alkanes or cycloalkanes such as methane, ethane, propanes, butanes, pentanes, hexanes, heptanes, cyclopropane, cyclohexane, etc., particularly alkanes having about 1 to 7 carbon atoms; ethylene, propylene, butylenes, Alkenes or cycloolefins such as pentenes, heptenes, cyclopentenes, especially alkenes having about 1 to 7 carbon atoms; alkynes such as acetylene and propyne, especially alkynes having about 1 to 7 carbon atoms; benzene, toluene, styrene, xylene, naphthalene , Aromatic or heteroaromatic hydrocarbons such as methylnaphthalene, indene and phenanthrene, especially aromatic or heteroaromatic hydrocarbons having about 6 to 18 carbon atoms, alcohols such as methanol and ethanol, especially about 1 to 7 carbon atoms Alcohols; other Combine two or more carbon compounds selected from carbon monoxide, ketones, ethers, etc., by adjusting the gas partial pressure so that different decomposition temperatures can be exhibited in the desired thermal decomposition reaction temperature range. The carbon fiber structure according to the present invention can be efficiently produced by using the material and / or adjusting the residence time in a predetermined temperature range and optimizing the mixing ratio.

  Among such combinations of two or more carbon compounds, for example, in the combination of methane and benzene, the molar ratio of methane / benzene is> 1 to 600, more preferably 1.1 to 200, still more preferably. It is desirable to set it as 3-100. This value is the gas composition ratio at the entrance of the reactor. For example, when toluene is used as one of the carbon sources, toluene is decomposed 100% in the reactor, and methane and benzene are 1 In consideration of the occurrence of: 1, a shortage of methane may be supplied separately. For example, when the methane / benzene molar ratio is 3, 2 moles of methane may be added to 1 mole of toluene. In addition, as methane added to such toluene, not only a method of preparing fresh methane separately, but also the unreacted methane contained in the exhaust gas discharged from the reactor is circulated and used. It is also possible to use it.

  By setting the composition ratio within such a range, it is possible to obtain a carbon fiber structure having a structure in which both the carbon fiber part and the granular part are sufficiently developed.

  Note that an inert gas such as argon, helium, or xenon, or hydrogen can be used as the atmospheric gas.

  As the catalyst, a transition metal such as iron, cobalt or molybdenum, or a mixture of a transition metal compound such as ferrocene or metal acetate and sulfur or a sulfur compound such as thiophene or iron sulfide is used.

  The synthesis of the intermediate is carried out by using a CVD method such as hydrocarbon which is usually performed, evaporating a mixed liquid of hydrocarbon and catalyst as raw materials, introducing hydrogen gas or the like into the reaction furnace as a carrier gas, Pyrolysis at a temperature of 1300 ° C. As a result, a plurality of carbon fiber structures (intermediates) having a sparse three-dimensional structure in which fibers having an outer diameter of 15 to 100 nm are bonded together by a granular material grown using the catalyst particles as nuclei are several cm to An assembly of several tens of centimeters in size is synthesized.

  The thermal cracking reaction of the hydrocarbon as a raw material mainly occurs on the surface of the granular particles grown using the catalyst particles or the core, and the recrystallization of carbon generated by the decomposition proceeds in a certain direction from the catalytic particles or granular materials. Grows in a fibrous form. However, in obtaining the carbon fiber structure according to the present invention, the balance between the thermal decomposition rate and the growth rate is intentionally changed. For example, as described above, at least two carbon sources having different decomposition temperatures are used. By using the above carbon compound, the carbon material is grown three-dimensionally around the granular material without growing the carbon material only in a one-dimensional direction. Such three-dimensional carbon fiber growth does not depend only on the balance between the thermal decomposition rate and the growth rate, but the crystal surface selectivity of the catalyst particles, the residence time in the reactor, the temperature distribution in the furnace, etc. In addition, the balance between the thermal decomposition reaction and the growth rate is influenced not only by the type of carbon source as described above but also by the reaction temperature and gas temperature. In general, when the growth rate is faster than the pyrolysis rate as described above, the carbon material grows in a fibrous form, whereas when the pyrolysis rate is faster than the growth rate, the carbon material is surrounded by catalyst particles. Grows in the plane direction. Therefore, by intentionally changing and controlling the balance between the thermal decomposition rate and the growth rate, the growth direction of the carbon material can be set to multiple directions instead of a fixed direction, and the three-dimensional structure according to the present invention can be formed. In this intermediate, the composition of the catalyst, residence time in the reactor, reaction temperature, gas temperature, etc. can be optimized in order to easily form a three-dimensional structure in which the fibers are bonded together by granular materials. desirable.

  The intermediate obtained as described above has an incomplete structure in which patch-like sheet pieces made of carbon atoms are bonded together, and has many defects. This intermediate contains unreacted raw material, non-fibrous carbide, tar content and catalytic metal.

  In the method for producing a carbon fiber structure of the present invention, a preliminary annealing process can be added as necessary. Specifically, the intermediate body of the carbon fiber structure obtained in the first step is heated at 800 ° C. to 1200 ° C. for 5 to 20 minutes between the first step and the second step. By this preliminary annealing treatment step, the unreacted raw material, non-fibrous carbide, tar content and part or all of the catalytic metal contained in the intermediate obtained in the first step are removed.

  Next, in the second step of the production method of the present invention, the carbon fiber structure intermediate obtained in the first step is immersed in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant. After that, the solvent used is removed by drying.

  A specific example of the second step of the present invention will be described below.

  An organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant is applied to the carbon fibers produced in the first step by spraying or the like, or batchwise or continuously immersed.

  Since carbon nanotubes have a low affinity for water, organic solvent solutions of organometallic compounds are easier to use. As the organometallic compound, alkoxides of metal such as Ti, V, Cr, Zr, Nb, Mo, Ta, W, and Y, acetylacetonate, fatty acid salts, and the like can be used. Also, an aqueous solution containing a salt of these metals and an inorganic acid and a surfactant can be used. These metals have a strong bonding force with carbon and form carbides.

  The method for drying and removing the solvent used is not particularly limited, and for example, natural drying or heat drying at a temperature of about 100 ° C. or lower, more preferably about 70 to 80 ° C. can be performed. For about 8 to 24 hours, typically about 12 hours.

  Thereafter, as a third step, an intermediate of the carbon fiber structure, which is immersed in an organic solvent solution of an organometallic compound in the second step or an aqueous solution of a metal salt and a surfactant and dried, is 800 ° C. to 1200 ° C., More preferably, heating is performed at 900 to 1000 ° C., and annealing treatment is further performed at 1800 ° C. to 3000 ° C., more preferably 2000 to 2600 ° C.

  If the annealing treatment is performed at a temperature lower than 1800 ° C., the crystallinity of the carbon fiber composite structure is lowered, and sufficient performance cannot be exhibited in terms of electrical conductivity, thermal conductivity, mechanical strength, etc., which is not preferable. Moreover, even if it is performed at a temperature higher than 3000 ° C., there is no further effect on the crystallinity development of the carbon fiber composite structure, which is not preferable in terms of high-temperature treatment costs.

  Although it does not specifically limit as processing time in each temperature range, It can be made into 5 to 20 minutes at 800 degreeC-1200 degreeC for about 5 to 20 minutes, and then 1800 degreeC-3000 degreeC. .

  At this time, a reducing gas or a small amount of carbon monoxide gas may be added to the inert gas atmosphere in order to protect the material structure.

  Since the carbon fiber composite structure of the present invention manufactured by the manufacturing method as described above is annealed at 1800 ° C. to 3000 ° C. in the third step, it has high durability against high temperatures. Moreover, since the carbon fiber composite structure has few defects due to the annealing treatment, the combustion start temperature is 700 ° C. or higher even in the air, and the thermal stability is high.

Incidentally, when annealing at 2400 ° C. or higher, with a true density narrowed spacing of graphene sheets stacked is increased from 1.89 g / cm ³ to 2.1 g / cm ^3, perpendicular to the axis the cross-section of the carbon fiber becomes a polygonal shape The carbon fiber having this structure is dense and has few defects both in the laminating direction and in the plane direction of the cylindrical graphene sheet constituting the carbon fiber, so that the bending rigidity (EI) is improved.

  The carbon fiber composite structure manufactured by the method for manufacturing a carbon fiber composite structure of the present invention has a three-dimensional network-like carbon fiber structure formed in the first step, and the network is a fine carbon fiber. Since they are not simply entangled with each other, but have a granular part that firmly bonds the fine carbon fibers together, as described above, when a composite material is finally produced, the composite material The thermal conductivity, electrical conductivity, and mechanical strength of the resin are good. Moreover, it is not necessary to add a process for imparting a three-dimensional structure.

  In the embodiment for obtaining a carbon fiber composite structure containing a boron compound as described above as the carbon fiber composite structure of the present invention, as a step for containing this boron compound, for example, as described above It can be performed by adding the following steps to the manufacturing process having the first to third steps.

  That is, in the second step described above, an organic solvent solution or an aqueous solution of a boron compound is mixed with an organic solvent solution or metal salt of an organic metal compound and an aqueous solution of a surfactant.

As the boron compound used here, simple boron, B ₂ O ₃ , H ₃ BO ₄ , B ₄ having physical properties that do not evaporate by decomposition or the like before reaching 1800 ° C. in the third step. C, BN, etc. are mentioned. Content of a boron compound is 0.001-30 mass% in conversion of boron with respect to a carbon fiber composite structure, Preferably it is 0.01-3.0 mass%. The site where the boron compound is present in the carbon fiber composite structure is a state in which a part of carbon atoms constituting the carbon fiber composite structure is substituted with boron, and a state where boron is attached to the surface of the carbon fiber composite structure. There is a state of being taken into metal fine particles contained on the surface of the carbon fiber composite structure. At this time, the boron compound can adopt various compound species. As described above, by the presence of the boron compound in the carbon fiber composite structure, high conductivity can be obtained even when the structure includes some defects.

(Preliminary body of carbon fiber composite structure)
Next, the preform of the carbon fiber composite structure according to the present invention will be described.
As described above, the preform of the carbon fiber composite structure of the present invention is a carbon fiber containing fine particles of metal and / or metal carbide on the surface of a carbon fiber structure having a specific three-dimensional network structure. A composite structure is formed, and the carbon fiber composite structure is obtained through a hot press and a carbonization process.

The shape and size of the preform of the carbon fiber composite structure according to the present invention are determined based on the shape and size of the composite material finally formed using the preform. The preform of the carbon fiber composite structure thus obtained has the characteristics of the carbon fiber composite structure according to the present invention as described above, has improved handling properties, and has further improved the composite material at the previous stage. The contact property with the matrix used when producing the molded body is improved. As a result, it is possible to facilitate the molding process of the finally produced composite material and to make the obtained molded body strong.
(Method for producing preform of carbon fiber composite structure)
The preform of the carbon fiber composite structure as described above is subjected to the first to third steps as described with respect to the above-described “method for producing a carbon fiber composite structure”, and a metal and / or metal carbide is formed on the surface thereof. The carbon fiber composite structure containing the fine particles of the carbon fiber composite structure is formed, and then the binder is added to the carbon fiber composite structure and hot-pressed at 100 ° C. to 200 ° C., and then 800 ° C. to 1200 ° C. Can be prepared by carbonization treatment. In FIG. 1, the order of the arrows on the right side of the drawing, that is, “carbon fiber structure production”, “drying after immersion in a metal solvent solution”, “annealing”, “drying after immersion in an organic solvent such as a thermosetting resin” , “Preparation of molded body by hot pressing”, “anneal carbonization” and “preliminary body of carbon fiber composite structure” are representative of the method for producing a preform of carbon fiber composite structure according to the present invention. And basic procedure.

  The first to third steps are the same as those described above, and are omitted for the sake of duplication. In this case, naturally, the preliminary annealing treatment as described above, the step for containing a boron compound is included. Of course, it is possible to add such additional steps or to adopt various modifications as described above.

  Then, the carbon fiber composite structure obtained through the third step is mixed and kneaded with a binder. As the binder, thermosetting resin, pitch or the like can be used, but is not limited thereto. The thermosetting resin has a property of being crosslinked, polymerized and solidified by a curing step by heating at about 100 to 200 ° C., and having a property of being decomposed and carbonized without being in a fluid state at the time of heating. preferable. Specifically, as the thermosetting resin, for example, phenol resin, urea resin, melamine resin, xylene resin, aniline resin, epoxy resin, polyamide resin, polyimide resin, diallyl phthalate resin, furan resin, polybenzoxazole resin, etc. Is mentioned. As the pitch, an isotropic pitch, a mesophase pitch, or the like can be used.

  A double-arm kneader, a mixer-type kneader, or the like can be used for mixing and kneading the carbon fiber composite structure and the binder. The mixing and kneading conditions are such that the carbon fiber composite structure formed by containing fine particles of metal and / or metal carbide in the carbon fiber structure having the specific three-dimensional structure does not substantially destroy the structure. There is no particular limitation as long as the shearing force and time are used. In addition, the conditions depend on the type of binder used, the mixing or kneading apparatus used, and therefore cannot be defined unconditionally. For example, the viscosity of the binder is 0.3 to 1000 mPa · s. For example, a process of 10 seconds to 10 minutes can be exemplified. If the binder can be uniformly mixed with the carbon fiber composite structure simply by treatment such as dipping, special treatment such as kneading or stirring is unnecessary. If necessary, the binder can be diluted with a solvent or heated to adjust the viscosity during mixing.

Following mixing and kneading, molding by hot pressing is performed. For molding, a method of pressing from above and below using a metal mold, a method of isotropic pressing using hydrostatic pressure using a rubber mold, and the like are preferable. Molding pressure at the time of pressing are ^{1 × 10 5 ~2 × 10 8} P.

  When a thermosetting resin is used as a binder, the thermosetting resin can be cured simultaneously with molding by heating to a curing temperature of the thermosetting resin, for example, 100 to 200 ° C. during pressing.

  After forming by hot pressing, the thermosetting resin is decomposed and carbonized by heating to, for example, 800 to 1200 ° C. in a deoxygenated atmosphere or an inert gas atmosphere, and further graphitized. A preform of the carbon fiber composite structure can be manufactured through these series of steps.

The shape and size of the preform of the carbon fiber composite structure are determined based on the shape and size of the composite material that is finally formed using the preform. The carbon fiber composite structure preform thus obtained has voids inside, and in the further stage, the voids are impregnated with a matrix material to produce a composite molded body. . At the time of impregnation, the contact between the preform of the carbon fiber composite structure and the matrix becomes good, and the adhesion between the carbon fiber composite structure and the matrix becomes stronger due to the anchor effect. As a result, the composite material finally produced can be made stronger.
(Use of carbon fiber composite structure and carbon fiber composite structure preform)
Carbon fiber composite structure and carbon fiber composite structure preform according to the present invention as described above, or carbon fiber composite structure manufacturing method and carbon fiber composite structure preform according to the present invention as described above As described above, the carbon fiber composite structure and the carbon fiber composite structure preform obtained by the method for producing the body have good and stable properties such as conductivity, thermal conductivity, and dispersibility in the matrix. Taking advantage of these, it can be suitably used in a wide range as a filler for composite materials for solid materials such as resins, ceramics and metals.

  Next, in the composite material using the carbon fiber composite structure and the carbon fiber composite structure preform according to the present invention, as a matrix for dispersing the carbon fiber composite structure as described above, an organic polymer, an inorganic material, A metal etc. can be used preferably.

  Examples of organic polymers include polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyacetal, polyethylene terephthalate, polycarbonate, polyvinyl acetate, polyamide, polyamideimide, polyetherimide, polyetheretherketone, polyvinyl alcohol, polyphenylene ether, and poly (meth) acrylate. And various thermoplastic resins such as liquid crystal polymers, epoxy resins, vinyl ester resins, phenol resins, unsaturated polyester resins, furan resins, imide resins, urethane resins, melamine resins, silicone resins and urea resins, Natural rubber, styrene / butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), ethylene / propylene rubber (EPDM), Various elastomers such as tolyl rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), urethane rubber, silicone rubber, fluorine rubber, acrylic rubber (ACM), epichlorohydrin rubber, ethylene acrylic rubber, norbornene rubber and thermoplastic elastomer Is mentioned.

  The organic polymer may be in the form of various compositions such as adhesives, fibers, paints, and inks.

  That is, the matrix is, for example, epoxy adhesive, acrylic adhesive, urethane adhesive, phenol adhesive, polyester adhesive, vinyl chloride adhesive, urea adhesive, melamine adhesive, olefin adhesive Adhesives, vinyl acetate adhesives, hot melt adhesives, cyanoacrylate adhesives, rubber adhesives and cellulose adhesives, acrylic fibers, acetate fibers, aramid fibers, nylon fibers, novoloid fibers, Cellulose fiber, viscose rayon fiber, vinylidene fiber, vinylon fiber, fluorine fiber, polyacetal fiber, polyurethane fiber, polyester fiber, polyethylene fiber, polyvinyl chloride fiber, polypropylene fiber and other fibers, phenol resin paint, alkyd resin paint Epoxy resin paint, Acrylic resin paint, unsaturated polyester paint, polyurethane paint, silicone paint, fluorine resin paint may be a paint such as a synthetic resin emulsion based paint.

  Examples of the inorganic material include a ceramic material, an inorganic oxide polymer, and a carbon-based material. Specifically, for example, carbon materials such as carbon carbon composites, glass, glass fibers, sheet glass and other molded glass, silicate ceramics and other refractory ceramics such as aluminum oxide, silicon carbide, magnesium oxide, silicon nitride And boron nitride.

  When the matrix is a metal, for example, a metal such as aluminum, magnesium, titanium, zinc, chromium, copper, silver, lead, copper, or an alloy or a mixture of two or more of these metals can be used.

  Further, the composite material may contain other fillers in addition to the carbon fiber structure described above. Examples of such fillers include metal fine particles, silica, calcium carbonate, magnesium carbonate, carbon black, glass, and the like. A fiber, carbon fiber, etc. are mentioned, These can be used 1 type or in combination of 2 or more types.

  The composite material includes an effective amount of the carbon fiber composite structure or the preform of the carbon fiber composite structure according to the present invention in the matrix as described above. The amount varies depending on the use of the composite material and the matrix, but can be, for example, about 0.1% to 98%. If it is less than 0.1%, the reinforcing effect of strength as a structural material is small, and the electrical conductivity is not sufficient. If it exceeds 98%, the characteristics of the matrix material cannot be exhibited sufficiently. In the composite material using the carbon fiber composite structure or the preform of the carbon fiber composite structure according to the present invention, fine carbon fibers can be arranged in the matrix with a uniform spread, and a metal is formed on the surface thereof. In addition, since it has fine particles of metal carbide, it is a composite material useful as a functional material excellent in electrical conductivity, thermal conductivity, radio wave shielding properties, etc., a structural material having high strength, and the like.

  Hereinafter, the present invention will be described more specifically based on examples. In the following, each physical property value was measured as follows.

<Area-based circle equivalent average diameter>
First, a photograph of the carbon fiber structure is taken with an SEM. In the obtained SEM photograph, only the carbon fiber structure with a clear outline was targeted, and the carbon fiber structure with a broken outline was not targeted because the outline was unclear. All carbon fiber structures (about 60 to 80) that can be targeted in one field of view were used, and about 200 carbon fiber structures were targeted in three fields of view. Trace the contour of each carbon fiber structure targeted using image analysis software WinRoof (trade name, manufactured by Mitani Corp.), obtain the area within the contour, and calculate the equivalent circle diameter of each fiber structure This was averaged.

<Measurement of bulk density>
A transparent cylinder with an inner diameter of 70 mm is filled with 1 g of powder, and air with a pressure of 0.1 Mpa and a capacity of 1.3 liters is sent from the lower part of the dispersion plate to blow out the powder and let it settle naturally. At the time of blowing out 5 times, the height of the powder layer after settling is measured. At this time, the number of measurement points was six, and after calculating the average of the six points, the bulk density was calculated.

<Raman spectroscopy>
Using a Yin Lab LabRam HR-800-Horiba manufactured by Horiba Jobin Yvon, measurement was performed using a wavelength of 514 nm of an argon laser.

<TG combustion temperature>
Using TG-DTA manufactured by Mac Science, the temperature was increased at a rate of 10 ° C./min while circulating air at a flow rate of 0.1 liter / min, and the combustion behavior was measured. During combustion, TG indicates a decrease in weight, and DTA indicates an exothermic peak. Therefore, the top position of the exothermic peak was defined as the combustion start temperature.

<X-ray diffraction>
Using a powder X-ray diffractometer (JEOL-JDX-3532, manufactured by JEOL Ltd.), the carbon fiber composite structure or carbon fiber structure after the annealing treatment was examined. The Kα ray generated at 40 kV and 30 mA in a Cu tube is used, and the surface spacing is measured according to the Gakushin method (the latest carbon material experiment technology (analysis and analysis), edited by the Carbon Materials Society of Japan). Used as internal standard.

<Average particle size of granular part, circularity, ratio with fine carbon fiber>
Similar to the measurement of the area-based circle-equivalent mean diameter, first, a photograph of the carbon fiber structure is taken with an SEM. In the obtained SEM photograph, only the carbon fiber structure with a clear outline was targeted, and the carbon fiber structure with a broken outline was not targeted because the outline was unclear. All carbon fiber structures (about 60 to 80) that can be targeted in one field of view were used, and about 200 carbon fiber structures were targeted in three fields of view.

  In each of the targeted carbon fiber structures, a granular portion that is a bonding point between carbon fibers is regarded as one particle, and its outline is defined by using image analysis software WinRoof (trade name, manufactured by Mitani Corporation). By tracing, the area in the contour was obtained, the equivalent circle diameter of each granular part was calculated, and this was averaged to obtain the average particle diameter of the granular part. Further, the circularity (R) is calculated based on the following equation from the area (A) in the contour measured using the image analysis software and the measured contour length (L) of each granular portion. Was averaged.

[Chemical 1]
R = A * 4π / L ²
Furthermore, the outer diameter of fine carbon fibers in each targeted carbon fiber structure is obtained, and the size of the granular portion in each carbon fiber structure is determined from this and the equivalent circle diameter of the granular portion in each carbon fiber structure. It calculated | required as a ratio with a fine carbon fiber, and averaged this.

<Content of fine particles in carbon fiber composite structure>
Metal elements were analyzed using a fluorescent X-ray measurement apparatus (Rigaku ZSXmini, manufactured by Rigaku Corporation). For confirmation, a metal carbide was separately detected using an X-ray diffractometer JEOL-JDX-3532 (manufactured by JEOL Ltd.).

<Surface coverage of carbon fiber structure by fine particles>
Observe the carbon fiber composite structure with TEM, count the number of metal and / or metal carbide fine particles observed at 500 nm length of the representative part of the surface of the carbon fiber composite structure, and analyze the image size of each fine particle Obtained by software and converted to the equivalent circle area (S _PA ). In diameter of the carbon fiber composite structure was measured, to calculate the surface area of the side where it is assumed that the cylinder (S _C). From these values obtained, the surface coverage was determined by the following formula.

[Chemical 2]
Surface coverage = ΣS _PA / S _c × 100 (%)

<Surface particle desorption test of carbon fiber composite structure>
A carbon fiber composite structure was added to 100 ml of toluene contained in a vial with a lid at a rate of 10 to 100 μg / ml to prepare a dispersion liquid sample of the carbon fiber composite structure.

  The dispersion sample of the carbon fiber composite structure thus obtained was subjected to ultrasonication using an ultrasonic cleaner having a transmission frequency of 38 kHz and an output of 150 w (trade name: USK-3, manufactured by SND Co., Ltd.). After 60 minutes from the application of ultrasonic waves, the carbon fiber composite structure was sampled from the dispersion liquid sample, dropped onto the mesh, and the sample was prepared.

[Example 1] Production of intermediate of carbon fiber structure (first step)
It was synthesized by a CVD method using toluene as a raw material. A mixture of ferrocene and thiophene was used as a catalyst, and the reaction was carried out under a reducing atmosphere of hydrogen gas. Toluene and catalyst were heated to 380 ° C. together with hydrogen gas, supplied to the production furnace, and thermally decomposed at 1250 ° C. to obtain an intermediate of the carbon fiber structure. A TEM photograph of this intermediate is shown in FIG.

[Example 2] Preliminary annealing treatment The intermediate of the three-dimensional network-like carbon fiber structure obtained in Example 1 was baked at 900 ° C in nitrogen to separate hydrocarbons such as tar. A preliminary annealing treatment was performed. The R value (I _D / I _G ) of the Raman spectroscopic measurement of the obtained intermediate was 0.98. A TEM photograph of this intermediate is shown in FIG.

[Example 3] Application of organometallic compound (second step)
2.3 g of titanium tetraisopropoxide (manufactured by Kanto Chemical Co., Inc.) was diluted with 50 ml of ethanol to prepare an immersion liquid. The intermediate body of the three-dimensional network-like carbon fiber structure obtained in Example 2 was immersed for 30 minutes at room temperature, and then dried at 100 ° C. for 12 hours.

[Example 4] Annealing treatment (third step)
The intermediate body 10g of the three-dimensional network-like carbon fiber structure after immersion and drying obtained in Example 3 was annealed at 2500 ° C for 20 minutes. The finally obtained annealed three-dimensional network-like carbon fiber structure was analyzed for metal elements using a fluorescent X-ray measurement apparatus Rigaku ZSXmini (manufactured by Rigaku Denki Kogyo Co., Ltd.). The finally obtained three-dimensional network-like carbon fiber composite structure after the annealing treatment contained 3.5% of Ti. FIGS. 5A and 5B show TEM photographs of the carbon fiber composite structure coated with the metal carbide fine particles. The size of the metal carbide fine particles adhering to the surface of the carbon fiber structure was about 50 nm as an average value of 15 fine particles. Separately, TiC was detected using an X-ray diffractometer JEOL-JDX-3532 (manufactured by JEOL Ltd.). The X-ray diffraction measurement results are shown in FIG.

  For comparison, the intermediate obtained in Example 2 is annealed at 2500 ° C. for 20 minutes, and the result of X-ray diffraction measurement is also shown in FIG.

  Furthermore, when the surface coverage of the carbon fiber structure by the fine particles in the carbon fiber composite structure obtained in this example was examined, it was determined to be 15%.

Further, the R value (I _D / I _G ) measured by Raman spectroscopy (manufactured by Jobin Yvon LabRam HR-800-Horiba) was 0.11.

Further, the obtained carbon fiber composite structure had a circle-equivalent mean diameter of 180 μm, a bulk density of 0.0031 g / cm ³ , a TG combustion temperature of 800 ° C., and a face spacing of 3.392 Å.

  Further, the average particle size of the granular portion in the carbon fiber structure was 350 nm (SD 180 nm), which was 5.8 times the outer diameter of the fine carbon fiber in the carbon fiber structure. Further, the circularity of the granular part was 0.69 (SD 0.15) on average.

  Further, when the surface fine particle detachment test of the carbon fiber composite structure was performed according to the above-described procedure, it was clear that the fine particles were not dropped off and the metal carbide fine particles were stably fixed on the surface of the carbon fiber structure. It became.

Example 5 Second Step + Boron Compound, Third Step After dissolving 2.0 g of B ₂ O ₃ (manufactured by High Purity Chemical Laboratory Co., Ltd.) in 200 ml of ethanol, titanium tetraisopropoxide (Kanto) 10 g of Chemical Co., Ltd.) was dropped and mixed to obtain an immersion liquid. The intermediate body of the three-dimensional network-like carbon fiber structure obtained in Example 2 was immersed in an immersion liquid at room temperature for 30 minutes, and then dried at 100 ° C. for 12 hours. 10 g of the intermediate body of the three-dimensional network-like carbon fiber structure after immersion and drying was heated to 900 ° C. for 20 minutes, and then annealed at 2400 ° C. for 20 minutes. The finally obtained annealed three-dimensional network-like carbon fiber structure was analyzed for metal elements using a fluorescent X-ray measurement apparatus Rigaku ZSXmini (manufactured by Rigaku Denki Kogyo Co., Ltd.). As a result of the analysis, the carbon fiber structure contained 8.0% Ti. Separately, TiC and TiB (TiB ₂ ) were detected using an X-ray diffraction measurement apparatus JEOLJDX-3532 (manufactured by JEOL Ltd.). The result of X-ray diffraction measurement is shown in FIG.

[Example 6] Molded article production example 8.0 g of the three-dimensional network-like carbon fiber structure after the annealing treatment obtained in Example 5 was added to a 60% by mass phenol resin register top (manufactured by Gunei Chemical Industry Co., Ltd.). ) Was soaked in 150 ml of methanol for 30 minutes. It dried for 12 hours on a 100 degreeC hotplate. The dried kneaded product was hot-pressed at 150 ° C. for 30 minutes using a hot press machine to obtain a molded body. The obtained molded body had a mass of 7.85 g, a diameter of 40 mm, a height of 7.5 mm, and a density of 0.83 g / cm ³ .

[Example 7] Preliminary body preparation example 7.85 g of the three-dimensional network-like carbon fiber structure body obtained in Example 6 was carbonized by heating at 1200 ° C for 20 minutes to obtain a carbon fiber composite structure. A body preform was obtained. The obtained preform had a mass of 5.97 g, a height of 8 mm, and a density of 0.59 g / cm ³ . The final carbonized carbon fiber composite structure preform obtained after carbonization was analyzed for metal elements using a fluorescent X-ray measuring device Rigaku ZSXmini (manufactured by Rigaku Denki Kogyo Co., Ltd.). It was. As a result of the analysis, the preform of the carbon fiber composite structure contained 8.0% Ti. Separately, TiC was detected using an X-ray diffractometer JEOLJDX-3532 (manufactured by JEOL Ltd.).

  Since the carbon fiber composite structure of the present invention is formed in a three-dimensional network shape, when the composite material is finally manufactured, its thermal conductivity, conductivity, and mechanical strength are good. Moreover, the process for providing a three-dimensional structure later is unnecessary. The carbon fiber composite structure of the present invention has high durability against high temperatures. Further, the fine particles of the metal and / or metal carbide that the carbon fiber composite structure has on the surface thereof have a strong bond with the carbon nanotubes, and the carbon fiber composite structure in the finally produced composite material Adhesion with the matrix becomes stronger. In addition, the fine metal particles that the carbon fiber composite structure of the present invention has on its surface act as a graphitization catalyst for the carbon compound. Therefore, the carbon fiber composite structure of the present invention can be suitably combined with various matrix materials such as metals and ceramics other than metals, rubber, synthetic resins, and carbon-based materials to form composites having excellent characteristics. Is.

  Although it does not specifically limit as a specific example of the utilization use of the carbon fiber composite structure of this invention, For example, the following can be mentioned. (1) Conductive resin, conductive molded body, thermally conductive resin, thermally conductive resin molded body, packaging material, gasket, container, resistor, electric wire, etc. as those utilizing conductivity and thermal conductivity. (2) Electromagnetic wave shielding materials, (3) Body materials such as home appliances, vehicles, and aircraft, machine housings, battery pole materials, etc. that utilize physical characteristics.

It is the process schematic in the manufacturing method of the carbon fiber composite structure of this invention. It is a conceptual diagram of the effect at the time of using the carbon fiber composite structure of this invention. It is a TEM photograph of an uncoated carbon fiber structure obtained in an example of the present invention. It is a TEM photograph of an uncoated carbon fiber structure obtained in an example of the present invention. (A) And (b) is the TEM photograph of the carbon fiber composite structure obtained by the Example of this invention by which the surface coat | covered TiC particle | grains. It is a chart which shows the XRD result of the carbon fiber composite structure which carried out the coating process of the TiC compound obtained in the Example of this invention, and the comparative example which does not carry out a coating process. It is a chart which shows the XRD result of the carbon fiber composite structure containing a boron compound in another Example of this invention.

Claims (18)

  It is a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm, and the carbon fiber structure is a mode in which a plurality of carbon fibers extend, and the carbon fiber structure is more than the outer diameter of the carbon fiber. The carbon fiber structure, which has a granular portion having a large particle size and bonds the carbon fibers to each other, and the granular portion is formed in the growth process of the carbon fibers, has a metal and a surface portion thereof. A carbon fiber composite structure characterized by containing fine particles of metal carbide. 2. The carbon fiber composite structure according to claim 1, wherein the carbon fiber composite structure has an I _D / I _G measured by Raman spectroscopy of 0.2 or less.   The carbon fiber composite structure according to claim 1 or 2, wherein the content of the fine particles of the metal and / or metal carbide is 1 to 200% by mass in terms of metal with respect to the carbon fiber structure.   The carbon fiber composite structure according to any one of claims 1 to 3, wherein the metal and / or metal carbide fine particles have a size of 1 to 70 nm.   The carbon fiber composite structure according to any one of claims 1 to 4, wherein the surface coverage of the carbon fiber structure by the metal and / or metal carbide fine particles is 1 to 100%.   The metal species of the metal and / or metal carbide described above is one or more selected from Ti, V, Cr, Zr, Nb, Mo, Ta, W, and Y. The carbon fiber composite structure according to any one item.   The above-described carbon fiber composite structure contains 0.001 to 30% by mass of a boron compound in terms of boron with respect to the carbon fiber composite structure, according to any one of claims 1 to 6. The carbon fiber composite structure according to 1.   It is a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm, and the carbon fiber structure is a mode in which a plurality of carbon fibers extend, and the carbon fiber structure is more than the outer diameter of the carbon fiber. A carbon fiber structure having a large particle size and a granular part for bonding the carbon fibers to each other, and the granular part formed in the growth process of the carbon fiber has a metal and / or a surface thereof. Alternatively, a carbon fiber composite structure preform formed by containing fine particles of metal carbide to form a carbon fiber composite structure, and the carbon fiber composite structure is obtained through a hot press and a carbonization process.   When the mixed gas of catalyst and hydrocarbon is heated at a constant temperature of 800 ° C. to 1300 ° C., the carbon material is grown in a fibrous form by using at least two carbon compounds having different decomposition temperatures as the carbon source. On the other hand, the first step of obtaining a three-dimensional network-like carbon fiber structure intermediate by growing it in the circumferential direction of the catalyst particles used, the obtained carbon fiber structure intermediate of the organometallic compound Second step of immersing in an organic solvent solution or an aqueous solution of a metal salt and a surfactant, and then drying the solvent used. After drying, the intermediate of the carbon fiber structure is heated to 800 ° C. to 1200 ° C., and then 1800 A three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm, comprising a third step of annealing at from ℃ to 3000 ℃, wherein the carbon fiber structure Is a mode in which a plurality of carbon fibers extend, and has a granular portion that has a particle size larger than the outer diameter of the carbon fiber and bonds the carbon fibers to each other, and the granular portion is a growth process of the carbon fiber A method for producing a carbon fiber composite structure, wherein the carbon fiber structure formed in step 1 contains fine particles of metal and / or metal carbide on the surface thereof. 10. The method for producing a carbon fiber composite structure according to claim 9, wherein the carbon fiber composite structure has an I _D / I _G measured by Raman spectroscopy of 0.2 or less.   The carbon fiber composite structure according to claim 9 or 10, wherein the content of the metal and / or metal carbide fine particles is 1 to 200% by mass in terms of metal with respect to the carbon fiber structure. Production method.   The method for producing a carbon fiber composite structure according to any one of claims 9 to 11, wherein the size of the metal and / or metal carbide fine particles is 1 to 70 nm.   The method for producing a carbon fiber composite structure according to any one of claims 9 to 12, wherein a surface coverage of the carbon fiber structure by the fine particles of the metal and / or metal carbide is 1 to 100%. .   A preliminary annealing treatment step of heating the carbon fiber structure intermediate obtained in the first step to 800 ° C. to 1200 ° C. is added between the first step and the second step. The method for producing a carbon fiber composite structure according to any one of claims 9 to 13.   The metal species of the organometallic compound described above is one or two or more selected from Ti, V, Cr, Zr, Nb, Mo, Ta, W, and Y. A method for producing a carbon fiber composite structure according to Item.   The method for producing a carbon fiber composite structure according to any one of claims 9 to 15, wherein the organometallic compound is a metal alkoxide, a metal acetylacetonate, or a metal fatty acid salt.   In the second step, the carbon fiber composite structure described above is prepared by mixing an organic solvent solution or an aqueous solution of a boron compound with an organic solvent solution or an aqueous solution of a metal salt and a surfactant. The method for producing a carbon fiber composite structure according to any one of claims 9 to 16, wherein 0.001 to 30% by mass of a boron compound in terms of boron is contained.   The method for producing a carbon fiber composite structure according to claim 9, wherein the carbon fiber structure is a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm that has undergone the third step. Is a mode in which a plurality of carbon fibers extend, and has a granular portion that has a particle size larger than the outer diameter of the carbon fiber and bonds the carbon fibers to each other, and the granular portion is a growth process of the carbon fiber The carbon fiber structure formed in step 1 contains a metal and / or metal carbide fine particles on its surface to form a carbon fiber composite structure, and a binder is added to the carbon fiber composite structure. A method for producing a preform of a carbon fiber composite structure, characterized by adding and hot pressing at 100 ° C. to 200 ° C. and then carbonizing at 800 ° C. to 1200 ° C.