JP2008248457A - Carbon fiber composite and method for producing the carbon fiber composite - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-dimensional network-like carbon fiber composite having a graphene layer forming a protrusions on the surface and suitable for composite materials. <P>SOLUTION: The carbon fiber composite has a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outside diameter 15-100 nm. The carbon fiber structure has granular parts having a larger particle size than the outside diameter of the carbon fiber, mutually binding the carbon fibers and formed in a growing process of the carbon fiber. The surface of the carbon fiber structure is covered with one layer or multilayers of graphene layers forming protruded portions protruding almost in radial directions of the carbon fiber constituting the carbon fiber structure. In the protruded portions, portions locating between the graphene layers and the surface of the carbon fiber have a structure in which fine metal particles or fine metal carbide particles are enclosed, or a hollow structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fine carbon fiber composite, and more particularly to a carbon fiber that has been surface modified by having a graphene layer that forms a protrusion on the surface of the carbon fiber.

  Fine carbon fibers typified by carbon nanotubes have excellent mechanical properties, high electrical conductivity, thermal conductivity, and other properties. For example, filler materials blended into various materials such as synthetic resins, rubber, ceramics, and metals It is expected to improve physical properties by forming composite materials. However, as can be seen from many research results, carbon nanotubes with few defects on the surface have weak interfacial adhesion to matrix materials (eg, synthetic resin, rubber, ceramics, metal, etc.), so pull-out Phenomena occur and sufficient physical properties cannot be obtained. This is the reality of the field of composite materials containing carbon nanotubes.

  Moreover, the following is pointed out about the composite material containing a carbon nanotube (refer nonpatent literature 1). That is, what is important in developing the mechanical strength is the adhesive strength between the carbon nanotube and the matrix material. The matrix material may be metal, ceramics, synthetic resin, carbon, etc., but the surface structure with few defects of carbon nanotubes works to deteriorate the wettability with the matrix metal etc. usually used in composite materials for structural materials In order to obtain a composite material with high strength, it is necessary to modify the surface of the carbon nanotubes or to 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).

  From the above viewpoints, the surface strength of carbon nanotubes is increased to improve the adhesion strength with the matrix material, for example, chemical surface modification such as introduction of functional groups on the surface of carbon nanotubes, or oxygen plasma (Oxygen plasma) There is a report of improving the interfacial adhesion strength with the matrix material by increasing the surface defects of the carbon nanotubes by a method such as oxidation treatment (for example, see Patent Documents 1 to 3). However, such a modification method is undesirable from the viewpoint of improving the physical properties of the composite material because the physical properties of the carbon nanotubes themselves are reduced due to an increase in surface defects of the carbon nanotubes.

  In addition, the coating treatment of the carbon nanotube surface according to the matrix material is a well-considered method. For example, a method of covering a carbon nanotube surface with a metal coating layer for a metal composite material (see, for example, Patent Documents 4 to 6), and a ceramic-based composite material by a sol-gel method, a CVD method, or a conversion method using SiO gas, A method for forming a film (see, for example, Patent Documents 7 and 8) and a method such as polymer wrapping (for example, see Non-Patent Document 3) have been proposed in the case of a resin-based composite material.

  Patent Document 4 reports 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 for ion exchange. . 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, in Patent Document 5, 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 formed at 130 to 150 ° C, 280 to 300 ° C. (Example 1) to form a titanium oxide film. This film improves the adhesion between the matrix material and the carbon fibers and improves the interlaminar shear strength. However, even in this case, the coating layer on the carbon nanotube surface remains uneasy in terms of strength.

  Patent Document 6 discloses that a plurality of carbon nanotubes, a carbide forming metal and a matrix metal are subjected to pressure sintering at a temperature equal to or higher than the melting point of the matrix metal to form a metal carbide on the surface of the plurality of carbon nanotubes. It has been reported to produce a highly thermally conductive heat dissipation material that makes it possible to obtain good adhesion between the matrix metal and the carbon nanotubes. In this case, the metal carbide coats the carbon nanotube aggregates (multiple carbon nanotubes), and further, different metals from both the metal matrix and the metal carbide source having different metal species must be charged at the same time. Only it is limited to some metals.

  As shown in Patent Documents 7 and 8, in the method of forming a SiC film on the surface of a carbon nanotube, since the affinity between SiC and carbon is relatively good, improvement in bonding strength with a ceramic matrix can be expected to some extent. However, the delamination phenomenon based on the difference in thermal expansion between the carbon nanotube and SiC often occurs under use conditions with a severe heat history. Further, according to the conversion method, the carbon nanotube itself is consumed as a carbon source for generating SiC.

  Non-Patent Document 3 discloses a method of lapping a carbon nanotube surface with a polymetafinylene-vinylene polymer, but this is insufficient in terms of electrical characteristics and optical characteristics. There are also limited resins with high affinity.

Further, as described above, the coating treatment on the surface of the carbon nanotubes according to the matrix material inevitably limits the applicable matrix material.
On the other hand, 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 9). 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 step, the fibrous carbonaceous materials are joined to each other (for example, see Patent Document 10).

  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 impregnated materials after the carbonization step (see, for example, Patent Document 11).

  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.

  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 that coats the surface of the carbon fiber reported above with metal is not the example of adopting a three-dimensional network-like carbon fiber structure. Of course, a graphene layer is provided on the coated metal. There is no example showing the structure.

On the other hand, a report on a three-dimensional network-like carbon fiber structure has also been made (for example, see Patent Document 12). 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 2003-300716 A JP-T-2004-535349 Special table 2003-505332 gazette Japanese Patent No. 2953996 Japanese Patent Publication No. 63-60152 JP 2004-10978 A JP 2005-75720 A JP 05-229886 A JP 2004-119386 A JP 2005-178151 A JP 2004-315297 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 A. Star, JF Stoddart, D. Steuerman, M. Diehl, A. Boukai, EW Wong, X. Yang, S.-W. Chung, H. Choi, JR Heath, Angew. Chem. Int. Ed. 2001, 40, 1721-1725.

  As described above, in order to improve the mechanical strength, thermal conductivity, and conductivity 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 a coating such as metal, ceramics (SiC), or polymer on the surface of carbon nanotubes, the method that does not perform post-treatment at high temperature depends only on the physical bond strength, so the strength of the coating is uncertain. Remains. Especially for applications at high temperatures, the heat resistance against heat is low, so the surface modification effect may be lost. In addition, a method of chemically reacting with a carbon nanotube to introduce a functional group on the surface of the tube and coating the surface of the carbon nanotube with metal, or a method of increasing defects on the surface of the carbon nanotube by chemical surface modification and low-temperature heat treatment, Since the structure may be adversely affected, the effect of finally improving the performance of the composite material cannot be obtained sufficiently. 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 nanotubes. 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, rubbers, ceramics, and carbon-based materials.

  The present invention does not require a process for imparting a three-dimensional structure to a carbon fiber when manufacturing a composite material, and a graphene layer that forms a protrusion on the surface of a carbon nanotube having a surface structure with few defects. The object of the present invention is to provide a carbon fiber composite, particularly a three-dimensional network-like carbon fiber composite, which has a strong bonding force between the graphene layer and the carbon nanotube by post-treatment at a high temperature.

  As a result of intensive studies on the above problems, the present inventors applied a specific organometallic compound and a specific resin to the surface of the carbon fiber, and processed at a high temperature, thereby forming a protrusion on the surface of the carbon nanotube. The inventors have found that a graphene layer to be formed is formed, and have completed the present invention.

  That is, according to the present invention, the carbon fiber is coated with a single-layer or multi-layer graphene layer that forms a protrusion that protrudes in a substantially radial direction of the carbon fiber, and the single-layer or multi-layer graphene is formed on the protrusion. The part sandwiched between the layer and the carbon fiber surface as a base is a carbon fiber composite characterized in that it has a structure in which metal fine particles or metal carbide fine particles are contained or is hollow.

  Moreover, the present invention is a three-dimensional network-like carbon fiber structure in which the above-described carbon fibers are 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. The carbon fiber has a granular part that is larger than the outer diameter of the carbon fiber and bonds the carbon fiber to each other, and the granular part is formed during the growth process of the carbon fiber. A fiber composite is shown.

  Furthermore, the present invention provides a single-layer or multi-layer graphene layer in which carbon fibers are preformed through a hot press in the course of the production process, and the surface of the carbon fibers forms a protruding portion projecting in a substantially radial direction of the carbon fibers. The portion sandwiched between the single-layer or multi-layer graphene layer and the surface of the basic carbon fiber in the protruding portion has a structure in which metal fine particles or metal carbide fine particles are included or is hollow. Is a carbon fiber composite preform.

The present invention also provides a first step in which a mixed gas of a catalyst and a hydrocarbon is heated at a constant temperature of 800 ° C. to 1300 ° C. to grow a carbon substance into a fiber to obtain a carbon fiber intermediate, and the obtained carbon After the fiber intermediate is immersed in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant, the second step of drying the solvent used is further immersed in an organic solvent solution of a binder, and then organic A third step of drying the solvent, and a fourth step of heating the carbon fiber intermediate after drying at 800 ° C. to 3000 ° C.,
The surface of the carbon fiber is covered with a single-layer or multi-layer graphene layer that forms a protrusion that protrudes substantially in the radial direction of the carbon fiber, and the single-layer or multi-layer graphene layer serves as a backbone in the protrusion. The portion sandwiched between the surfaces of the carbon fibers is a method for producing a carbon fiber composite characterized in that it has a structure in which metal fine particles or metal carbide fine particles are included or is hollow.

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 step of drying the solvent used is further immersed in an organic solvent solution of the binder, and then the organic solvent is dried. The third step consists of a fourth step of heating the carbon fiber structure intermediate after drying at 800 ° C. to 3000 ° C.,
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 granular part having a large particle size and bonding the carbon fibers to each other, and the granular part being formed in the growth process of the carbon fiber, The carbon fiber constituting the fiber structure is covered with a single-layer or multi-layer graphene layer that forms a protrusion that protrudes substantially in the radial direction of the carbon fiber. The part sandwiched between the surfaces has a structure in which metal fine particles or metal carbide fine particles are encapsulated or hollow. It shows a.

  In the carbon fiber composite of the present invention, in the protruding portion, the portion sandwiched between the single-layer or multi-layer graphene layer and the surface of the basic carbon fiber contains metal fine particles or metal carbide fine particles, or is hollow. Although it is characterized in that it is hollow, the hollow particles are formed because the metal fine particles that existed in the third step are desorbed by sublimation or the like in the fourth step. In addition, the single-layer or multi-layer graphene layer that forms the protruding portion may cover the entire surface of the carbon fiber serving as the backbone, or may partially cover the surface of the carbon fiber. In any case, the protruding portion formed by the graphene layer exhibits an anchor effect for strengthening the adhesion between the carbon fiber and the matrix.

  Moreover, in the manufacturing method of the carbon fiber composite of this invention, it hot-presses at 100 to 200 degreeC with respect to the intermediate body of the carbon fiber after the 2nd process and the 3rd process after drying, and carbon fiber composite A body preform can be produced. The carbon fiber preform thus obtained is subjected to a heat treatment in the fourth step, and when the composite material is produced in the previous stage, the contact with the matrix to be used is good, and as a result Thus, the composite material molded body can be made strong.

  In the method for producing a carbon fiber composite of the present invention, high-temperature heat treatment is performed in the fourth step, and if necessary, the carbon fiber intermediate obtained in the first step is interposed between the first step and the second step. A pre-annealing step can be added, heating to 800-1200 ° C.

The present invention also relates to the carbon fibrous structure, showing the carbon fiber composite I _{D /} I _G which is determined by Raman spectroscopy, characterized in that at least 0.2.

  The present invention further shows the carbon fiber composite, wherein a part of the single-layer or multi-layer graphene layer described above and the carbon fiber serving as the backbone are integrated in the crystal structure.

  The present invention further provides the carbon fiber composite in which the surface coverage of the carbon fiber structure by each protrusion formed by the one or more layers of the graphene layer is 1 to 70%, preferably 10 to 70%. It shows the body. The surface coverage is a value obtained by image analysis of an electron micrograph of the obtained carbon fiber composite surface.

  The present invention also shows the carbon fiber composite in which the size of each protrusion formed by the above-described single-layer or multilayer graphene layer is 5 to 70 nm, preferably 10 to 50 nm. In this case, the size of the protruding portion is represented by the length of the carbon fiber in the axial direction.

  Further, in the carbon fiber composite of the present invention, the portion sandwiched between the single-layer or multi-layer graphene layer and the surface of the basic carbon fiber in the protruding portion encloses metal fine particles or metal carbide fine particles, or The metal species used for the fine particles of these metals and / or metal carbides is preferably selected from Ti, V, Cr, Zr, Nb, Mo, Ta, W and Y. 1 type or 2 types or more.

  In addition, the present invention contains 0.001 to 30% by mass, preferably 0.01 to 3.0% by mass of a boron compound in terms of boron with respect to the carbon fiber composite, and the above-described single-layer or multi-layer graphene The portion sandwiched between the layer and the surface of the carbon fiber serving as the backbone indicates the carbon fiber composite having a structure in which metal fine particles, metal carbide or metal boride fine particles are included or hollow.

  In the method for producing a carbon fiber composite of the present invention, the obtained carbon fiber or carbon fiber structure intermediate was immersed in an organic solvent solution of an organic metal compound or an aqueous solution of a metal salt and a surfactant and then used. The second step of drying the solvent and the third step of drying the organic solvent after immersing in the organic solvent solution of the binder are performed. However, the second step and the third step can be performed simultaneously. Moreover, a 3rd process can be performed before a 2nd process.

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

  Furthermore, the present invention provides an organic solvent solution or aqueous solution of a boron compound with respect to an organic solvent solution of an organic metal compound or an aqueous solution of a metal salt and a surfactant during the second step of the method for producing the carbon fiber composite. The carbon fiber composite manufacturing method characterized by containing 0.001-30 mass% boron compound in conversion of boron with respect to an above described carbon fiber composite by mixing.

  Since the carbon fiber composite of the present invention has a graphene layer composed of one layer or a plurality of layers forming a protruding portion on the surface, the graphene layer is stable even at a temperature of 3000 ° C. or more, and therefore has high temperature durability. A high surface modification effect is obtained. In addition, the carbon fiber composite has a graphene layer composed of one or a plurality of layers forming a protruding portion on the surface thereof, and the surface of the carbon fiber (carbon nanotube) as a main part and a part thereof has a crystal structure. Since it can be integrated, the connection with the carbon nanotubes is strong, and the protrusions are formed, so the anchor effect of the protrusions in the composite material finally produced using this carbon fiber composite This strengthens the adhesion between the carbon fiber composite and the matrix. Furthermore, the graphene layer consisting of one or more layers that form the protrusions on the surface of the carbon fiber composite has no adverse effect on the structure of the carbon nanotubes. There is no risk of deterioration of physical properties. Further, in the carbon fiber composite of the present invention, the basic carbon fiber 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 carbon. In a mode in which a plurality of fibers are extended, the carbon fiber has a granular portion that has a particle size larger than the outer diameter of the carbon fiber and couples the carbon fibers to each other, and the granular portion is formed during the growth process of the carbon fiber. Since the carbon fiber composite of the present invention is formed in a three-dimensional network form, when the composite material is finally manufactured, its thermal conductivity, electrical conductivity, and mechanical strength are It will be good. Moreover, the process for providing a three-dimensional structure later is unnecessary. The fine metal particles on the surface of the carbon fiber composite act as a graphitization catalyst for the carbon compound during the heat treatment. In the carbon fiber composite of the present invention, metals and 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)
First, the carbon fiber composite according to the present invention will be described.

  In the carbon fiber composite according to the present invention, the surface of the carbon fiber is coated with a single-layer or multi-layer graphene layer that forms a protruding portion protruding substantially in the radial direction of the carbon fiber. The portion sandwiched between the single-layer or multi-layer graphene layer and the basic carbon fiber surface has a structure in which metal fine particles or metal carbide fine particles are included or hollow.

  In the carbon fiber composite of the present invention, the carbon fiber serving as the backbone is not particularly limited and can take various forms.

  Specifically, as the carbon fiber, for example, a single-walled carbon nanotube having a diameter of about several nanometers formed by rounding a single graphene sheet, or a multi-walled carbon nanotube in which cylindrical graphene sheets are stacked in a direction perpendicular to the axis (Multi-walled carbon nanotubes), carbon nanohorns such as single-walled carbon nanotubes with conical closed ends are included, and these carbon fibers are not limited to single-fibered ones, but branched ones, It may have a three-dimensional structure. In the present invention, these carbon fibers can be used alone or as a mixture of two or more kinds as described above.

  Further, the fiber properties such as the fiber diameter, fiber length, and aspect ratio of the carbon fiber are not particularly limited. However, the carbon fiber composite according to the present invention is uniformly formed in the matrix in constituting the composite material. It is desirable to have properties that can be dispersed. Although not particularly limited, for example, a fiber having a fiber diameter of about 0.5 to 120 nm and a fine carbon fiber having an aspect ratio of about 5 to 5,000 can be exemplified.

  Further, the carbon fiber is preferably a three-dimensional network-like carbon fiber structure having a predetermined structure as described in detail below.

  That is, in a preferred embodiment of the present invention, the carbon fiber 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 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 constituting the carbon fiber structure is covered with a single-layer or multi-layer graphene layer that forms a protruding portion protruding substantially in the radial direction of the carbon fiber, and the protruding portion The portion sandwiched between the single-layer or multi-layer graphene layer and the carbon fiber surface serving as the backbone contains metal fine particles or metal carbide fine particles, or is hollow. It comes to have a certain structure.

  In a preferred embodiment of the carbon fiber composite according to the present invention, the outer diameter of the carbon fiber constituting the carbon fiber structure of the three-dimensional network that is the backbone is in the range of 15 to 100 nm. Is less than 15 nm, the cross section of the carbon fiber in the carbon fiber composite according to the present invention obtained by carrying out heat treatment after supporting a metal and attaching a binder as shown in the production method described later is not polygonal. On the other hand, as the diameter of the carbon fiber is smaller, the number per unit amount is increased and the length of the carbon fiber in the axial direction is increased, and high conductivity can be obtained, so having an outer diameter exceeding 100 nm This is because it is not suitable as a carbon fiber composite according to the present invention which is arranged 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 addition, it is desirable that the fine carbon fiber has an outer diameter that changes along the axial direction. When the outer diameter of the carbon fiber is not constant along the axial direction and changes, the carbon fiber is considered to have an anchor effect in the matrix such as resin, and movement in the matrix occurs. It is difficult to increase the dispersion stability.

  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 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.

  Further, the carbon fiber structure has a shape in which carbon fibers existing in a three-dimensional network are bonded to each other in a granular portion, and a plurality of the carbon fibers extend from the granular portion. In this case, when a plurality of granular portions that combine carbon fibers are present to form a three-dimensional network, the average distance between adjacent granular portions is, for example, 0.5 μm to 300 μm, more preferably 0.5 to It is about 100 μm, 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.

Further, as described above, the carbon fiber structure 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 , and more preferably 0.001 to 0.00. It is desirable to be 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.

Further, the carbon fiber structures, _I D / _{I G} ratio determined by Raman spectroscopy is, it is preferable 0.2 or more, more preferably about 0.2 to 1.6. 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 to 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 structure. In the carbon fiber composite according to the present invention, the I _D / _IG ratio of the carbon fiber structure that is the raw material has the above-mentioned high value, and the one having a disordered structure carries metal or the like. It is because it is easy to do. In addition, since the I _D / _IG ratio of the carbon fiber composite of the present invention finally obtained is obtained by heat treatment after attaching a metal as in the production method described later, it becomes a raw material. Compared to the I _D / _IG ratio in the carbon fiber structure, the value becomes lower and the amount of defects becomes smaller.

  In the carbon fiber composite of the present invention, as described above, the surface of the carbon fiber, particularly the carbon fiber structure having the three-dimensional network structure as described above, protrudes in the substantially radial direction of the carbon fiber. A portion covered with a single-layer or multi-layer graphene layer that forms a protrusion-shaped portion, and sandwiched between the single-layer or multi-layer graphene layer and the main carbon fiber surface in the above-mentioned protrusion-shaped portion is made of metal fine particles or metal carbide fine particles. If the single-layer or multi-layer graphene layer forming the protrusion is capable of forming the protrusion, the carbon fiber serving as the backbone is included. The whole surface may be covered, or the carbon fiber surface may be partially covered.

  As will be described later, such a graphene layer is obtained by immersing the carbon fiber or carbon fiber structure intermediate obtained on the surface of the carbon fiber in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant. Then, after the second step of drying the used solvent, and further after the third step of drying the organic solvent after being immersed in the organic solvent solution of the binder, the heat treatment is performed by performing the heat treatment in the fourth step. Sometimes, fine particles of metal are present on the surface of the carbon fiber, and the fine particles of the metal act as a graphitization catalyst for the carbon compound, so that a graphene layer is formed so as to surround the fine particles of the metal. A projection-like portion protruding substantially in the radial direction is formed.

  In the carbon fiber composite according to the present invention finally obtained, the portion sandwiched between the single-layer or multi-layer graphene layer and the surface of the basic carbon fiber in the protruding portion is a metal fine particle or a metal carbide. It is characterized by enclosing fine particles or being hollow, but the hollow is formed because the metal fine particles that existed in the third step are desorbed by sublimation or the like in the fourth step. In addition, the metal carbide fine particles are formed because the metal fine particles are also carbonized.

  In the carbon fiber composite according to the present invention, even if the inside of the protruding portion is any of metal fine particles, metal carbide fine particles, or hollow, the mechanical properties of the protruding portions and the composite material body In terms of the anchor effect, etc., there is no particular change.For example, when the magnetic properties and electrostatic properties of the carbon fiber composite are to be obtained, the internal structure and the It is desirable that

  The size of each protrusion formed by the above-described single-layer or multilayer graphene layer is not particularly limited, but is, for example, 5 to 70 nm, and preferably 10 to 50 nm. If the size of each protruding portion exceeds 70 nm, it may be difficult to stably form the protruding portion on the surface of the carbon fiber structure having an outer diameter in the range of 15 to 100 nm.

  Further, the height of each protrusion formed by the above-described single-layer or multilayer graphene layer is not particularly limited, but with respect to the outer diameter of the carbon fiber serving as the backbone in the substantially radial direction of the carbon fiber. Thus, it is desirable to have an average height of 0.05 to 1 times. When the average height is less than 0.05 times the outer diameter of the carbon fiber, surface modification that can be expected to have an anchor effect does not substantially occur, whereas when the average height exceeds 1 time, There is a possibility that it is difficult to stably form the protrusions on the carbon fiber surface.

  Furthermore, although not particularly limited, the protrusions formed by the above-described single-layer or multilayer graphene layer are, for example, about 1 to 70%, more preferably about 2 to 50% of the surface of the carbon fiber. This is desirable in order to provide a higher anchor effect and obtain a composite material that is particularly excellent in terms of mechanical properties.

  Furthermore, the thickness of the single-layer or multi-layer graphene layer that forms the protrusion is not particularly limited, but it exhibits sufficient mechanical strength and forms a protrusion having the expected size. For example, the thickness is preferably 2 to 15 nm, particularly 3 to 10 nm.

  As the metal species used for the metal and / or metal carbide fine particles included in the protrusions formed on the surface of the carbon fiber of the present invention, various types may be used depending on the properties to be added. However, preferable metal species are one or more selected from Ti, V, Cr, Zr, Nb, Mo, Ta, W, and Y.

  In the carbon fiber composite of the present invention, the protrusion is formed of a graphene sheet as the outer shell, and more preferably, a part of the graphene sheet is integrated with the carbon fiber and the crystal structure as a backbone, Its structure is stable and the bond with the carbon fiber is strong. For example, as shown in the examples to be described later, the carbon fiber composite is dispersed in a liquid medium, and ultrasonic waves of a predetermined frequency are applied to the carbon medium to examine the destruction rate of the protrusions. The fracture rate of the protrusions after the treatment is less than 1%, more preferably less than 0.1%, and it can be seen that the protrusions are stably formed on the carbon fiber.

  Further, since the fine particles form protrusions on the surface of the carbon fiber, in the composite material finally produced using the carbon fiber composite according to the present invention, the carbon fiber composite and the matrix are bonded. The situation is improved and it is strengthened by the anchor effect. When general carbon fiber is blended in the matrix as a filler, the surface of the filler is relatively smooth, so when strain stress is applied in the direction of the interface with the matrix, the matrix and the filler are displaced relatively easily. Will occur. On the other hand, when the carbon fiber composite according to the present invention is used, since the filler surface has the protrusions as described above, it appears as if it was driven in a wedge shape into the matrix at the interface with the matrix. Even when a strain stress is applied in the direction of the interface with the matrix, the matrix and the filler are less likely to be displaced.

In addition, since the protruding part which the carbon fiber composite of the present invention has on its surface is formed of a graphene sheet, there is no adverse effect on the structure of the carbon fiber, and the physical properties of the carbon fiber are improved by surface modification. There is no risk of deterioration.
Further, even at a high temperature of 3000 ° C. or higher under an inert atmosphere, the protrusions formed of the graphene sheet are stable and have extremely high heat resistance.

  As described above, the carbon fiber composite of the present invention has a protruding portion composed of a graphene sheet on the surface of the carbon fiber serving as the backbone, and in particular, the carbon fiber is three-dimensional as described above. In an embodiment having a network structure, and the network structure is not simply 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.

  The carbon fiber composite 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.

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

(Method for producing carbon fiber composite)
Next, a method for producing the carbon fiber composite according to the present invention as described above will be described.

  FIG. 1 is a chart schematically showing the order of steps in a carbon fiber composite manufacturing method and a carbon fiber composite preform manufacturing method according to the present invention.

  The carbon fiber composite according to the present invention is not particularly limited, but basically, a mixed gas of a catalyst and a hydrocarbon is heated at a constant temperature of 800 ° C. to 1300 ° C. A first step of obtaining a carbon fiber intermediate by growing the carbon fiber intermediate in an organic solvent solution of an organic metal compound or an aqueous solution of a metal salt and a surfactant; It consists of a second step of drying, a third step of immersing the binder in an organic solvent solution, and then drying the organic solvent, and a fourth step of heating the carbon fiber intermediate after drying at 800 to 3000 ° C.

  The basic carbon fiber is a three-dimensional network-like carbon fiber structure composed of carbon fibers having an outer diameter of 15 to 100 nm as described above, and the carbon fiber structure has a plurality of carbon fibers extending. The carbon fiber has a granular part larger than the outer diameter of the carbon fiber and bonds the carbon fiber to each other, and the granular part is formed in the growth process of the carbon fiber. In an embodiment, when the mixed gas of the catalyst and the hydrocarbon is heated at a constant temperature of 800 ° C. to 1300 ° C., the carbon material is obtained by using at least two or more carbon compounds having different decomposition temperatures as a carbon source. The first step of obtaining the intermediate of the three-dimensional network-like carbon fiber structure by growing in the direction of the circumference of the catalyst particles used while growing in the form of fibers After immersing the intermediate body of the fiber structure in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant, the second step of drying the solvent used, and further immersing in an organic solvent solution of a binder It can be produced by passing through a third step of drying the organic solvent and a fourth step of heating the carbon fiber structure after drying at 800 ° C. to 3000 ° C.

  FIG. 1 shows the order of steps in an embodiment according to such a three-dimensional network-like carbon fiber structure. That is, the first step of the flowchart is “carbon fiber structure production” as the first step, the second step is “drying after immersion in a metal solvent solution” as the second step, and the third step is the third step “ “Dry after immersion in an organic solvent such as a thermosetting resin” is shown. The third and subsequent steps of the flowchart are branched into two processes, but the left side is a flow relating to the powder (carbon fiber composite) according to the present example, and the right side is a preformed body to be described later. It is the flow of. In order to obtain the “carbon fiber composite powder” according to this example, the basic procedure is to perform “annealing” as the heat treatment in the fourth step after the third step.

  First, the 1st process of obtaining the intermediate body of carbon fiber 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 a carbon fiber structure having a three-dimensional network structure as described above, at least two or more carbon compounds having different decomposition temperatures may be used as a carbon source. preferable. 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 intermediate or carbon fiber structure intermediate obtained in the first step is used as an organic solvent solution of an organic metal compound or a metal salt and a surface activity. After immersing in an aqueous solution of the agent, 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.

  The third step of the present invention is performed as follows. A binder is added to the carbon fiber intermediate or carbon fiber structure intermediate after the second step and mixed and kneaded. As the binder, thermosetting resin, pitch or the like is used. The thermosetting resin has a property of being crosslinked, polymerized and solidified by a curing process 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, Those having a high carbon ratio in the molecule are preferred. 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 intermediate or carbon fiber structure intermediate and the binder. The mixing and kneading conditions are not particularly limited as long as the carbon fiber intermediate or carbon fiber structure intermediate is subjected to shearing force and time that do not substantially destroy the structure. 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. When the binder can be uniformly mixed with the carbon fiber intermediate or the carbon fiber structure intermediate simply by treatment such as immersion, 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.

  Examples of thermosetting resins that can be used in the present invention include phenolic resins, urea resins, melamine resins, xylene resins, aniline resins, epoxy resins, polyamide resins, polyimide resins, diallyl phthalate resins, diallyl phthalate resins, furan resins, poly resins. Examples thereof include benzoxazole resins.

  In addition, the 3rd process of this invention can also be implemented by changing order as follows. That is, with respect to the carbon fiber intermediate or carbon fiber structure intermediate obtained in the first step, the carbon fiber intermediate or carbon fiber structure intermediate after the second step is completed. The same operation as the third step is performed. This changes the order of the second step and the third step, but does not affect the possibility of implementing the present invention. Alternatively, the third step can be performed simultaneously with the second step. That is, the second step of attaching a metal and the third step of attaching a binder to the carbon fiber intermediate or carbon fiber structure intermediate obtained in the first step are simultaneously performed.

  The reason why a thermosetting resin is used as a preferable binder in the present invention is, for example, in the case of a phenol resin, an organometallic compound attached to the surface of a carbon fiber intermediate or a carbon fiber structure intermediate in the second step. Alternatively, as a result of the metal ions being encapsulated in the phenol resin, the metal component acts as a graphitization catalyst for the carbon compound (for example, phenol resin). For this reason, the graphene layer which consists of one layer or several layers which forms a projection-shaped part is formed in the surface of carbon fiber or a carbon fiber structure by the heat treatment of the 4th process. A part of the graphene layer composed of one layer or a plurality of layers and the carbon fiber or the carbon fiber structure are integrated with each other and have a strong structure. In the step of forming the graphene layer, the organometallic compound attached to the surface of the carbon fiber intermediate or the carbon fiber structure intermediate in the second step becomes fine particles of metal and / or metal carbide to form graphene. It is included in a portion sandwiched between the layer and the surface of the carbon fiber or the carbon fiber structure, and a protrusion is formed on the graphene layer. In addition, in the portion sandwiched between the graphene layer and the carbon fiber in the protruding portion, the metal fine particles or the metal carbide fine particles may be dissipated in the final, partial or whole of the annealing process in the fourth step. When dissipated, the part sandwiched between the graphene layer and the carbon fiber becomes partially or entirely hollow.

  Thereafter, as a fourth step, heat treatment is performed on the carbon fiber intermediate or the carbon fiber structure intermediate after the second and third steps. The center of the fourth step is an annealing process. As the fourth step, a carbon fiber intermediate or a carbon fiber structure intermediate graphene structure can be sufficiently developed, and a graphene sheet can be formed that forms protrusions on the carbon fiber surface as described above. If it is, it will not specifically limit, For example, it can carry out by performing heat processing in 800 to 3000 degreeC.

  As an example of a preferable heat treatment, first, after the completion of the second step and the third step, a dried carbon fiber intermediate or carbon fiber structure intermediate is heated to 800 ° C. to 1500 ° C., more preferably 900 to 1000 ° C. And annealing at 1500 ° C. to 3000 ° C., more preferably 1800 to 2600 ° C.

  As described above, when the annealing treatment is performed at a temperature in the range of 1800 ° C. to 3000 ° C., the resulting carbon fiber composite has high crystallinity and has sufficient performance in electrical conductivity, thermal conductivity, mechanical strength, and the like. This is also preferable in terms of high-temperature processing costs.

  Although it does not specifically limit as processing time in each temperature range, About 800 to 1500 degreeC can be 5 to 20 minutes, Next, 1500 to 3000 degreeC can be set to about 5 to 20 minutes.

  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.

  Note that the carbon fiber composite obtained by annealing at 1800 ° C. to 3000 ° C. in the fourth step has high durability against high temperatures. Moreover, since the carbon fiber composite has few defects due to the annealing treatment, the thermal start temperature is 700 ° C. or higher even in the air, and the thermal stability is high.

Furthermore, when annealed 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.

  In the embodiment for obtaining the carbon fiber composite containing the boron compound as described above as the carbon fiber composite 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 fourth 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 having physical properties that do not evaporate by decomposition or the like before reaching 1800 ° C. which is the temperature employed in the fourth step. BO ₄ , B ₄ C, BN and the like can be mentioned. Content of a boron compound is 0.001-30 mass% in conversion of boron with respect to a carbon fiber composite body, Preferably it is 0.01-3.0 mass%. The part where the boron compound is present in the carbon fiber composite is in a state where a part of carbon atoms constituting the carbon fiber composite is replaced with boron, in a state where boron is attached to the surface of the carbon fiber composite, carbon fiber There is a state of being taken into metal fine particles encapsulated in the vicinity of the surface of the composite (that is, encapsulated as a metal boride). At this time, the boron compound can adopt various compound species. As described above, the presence of the boron compound in the carbon fiber composite makes it possible to obtain high conductivity even when the structure includes some defects.

(Carbon fiber composite preform)
Next, the carbon fiber composite preform according to the present invention will be described.
As described above, the preform of the carbon fiber composite of the present invention is a carbon fiber, preferably a carbon fiber structure having a specific three-dimensional network structure as described above is hot-pressed during the manufacturing process. And the surface of the carbon fiber is coated with a single-layer or multi-layer graphene layer that forms a protrusion protruding substantially in the radial direction of the carbon fiber, and the single-layer or multi-layer is formed on the protrusion. The portion sandwiched between the graphene layer and the surface of the carbon fiber serving as the backbone has a structure in which metal fine particles or metal carbide fine particles are included or is hollow.

  The shape and size of the preform of the carbon fiber composite 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 thus obtained has the characteristics of the carbon fiber composite according to the present invention as described above, has improved handling properties, and is a composite molded body at a further stage. The contact property with the matrix used when producing the 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)
The preform of the carbon fiber composite as described above is a carbon fiber intermediate or carbon fiber structure that has undergone the first to third steps as described with respect to the above-described “method for producing a carbon fiber composite”. A carbon fiber intermediate or a carbon fiber structure intermediate is hot-pressed at 100 ° C. to 200 ° C. with a metal and binder attached to the surface of the intermediate, and then the same as described above. It can be prepared by subjecting it to a four-step heat treatment. That is, “carbon fiber structure generation” that is the first step in the first step of the flowchart shown in FIG. 1, “drying after immersion in a metal solvent solution” that is the second step in the second step, and third step in the third step. After the process “Drying in an organic solvent such as thermosetting resin and drying”, the third and subsequent steps in the flowchart are the flow shown on the right side, followed by “Hot pressing” and then the fourth heat treatment. The basic procedure is to perform “annealing”.

  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.

For forming by hot pressing, a method of pressing from above and below using a mold, a method of pressing isotropically with hydrostatic pressure using a rubber die, 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, heat treatment by the fourth step is performed. The fourth step is also the same as described above, and will not be described because the description is duplicated. Through these series of steps, a preform of the carbon fiber composite can be manufactured.

  The shape and size of the carbon fiber composite preform are determined based on the shape and size of the composite material that is finally formed using the preform. The carbon fiber composite 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 and the matrix becomes good, and the adhesion between the carbon fiber composite 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 composites and carbon fiber composite preforms)
Carbon fiber composite and carbon fiber composite preform according to the present invention as described above, or carbon fiber composite manufacturing method and carbon fiber composite preform according to the present invention as described above As described above, the carbon fiber composite obtained by the above and the carbon fiber composite preform have properties such as mechanical properties, electrical conductivity, thermal conductivity, good dispersibility in the matrix, and the like, Utilizing 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 and the carbon fiber composite preform according to the present invention, the matrix for dispersing the carbon fiber composite as described above includes organic polymers, inorganic materials, metals, and the like. It can be preferably used.

  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 composite, glass, glass fiber, 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 composite 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 or the carbon fiber composite preform 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 or the carbon fiber composite preform of the present invention, fine carbon fibers can be uniformly spread in the matrix, and metal and / or the surface thereof can be arranged. Alternatively, 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 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.

<Projection size>
The carbon fiber composite was observed by TEM, and the size of the protrusion on the surface of the carbon fiber composite was represented by the length of the carbon fiber in the axial direction. The average size was obtained by averaging the sizes of the 15 protruding fine particles in several fields of view.

<Height of the protruding part>
Observe the carbon fiber composite with TEM, and the height of the carbon fiber at the protrusion on the carbon fiber composite surface is approximately the maximum distance from the outermost graphene layer of the protrusion to the outermost surface of the carbon fiber in the radial direction. expressed. The average height was obtained by averaging the heights of 15 protrusions in several fields of view.

<Content of metal fine particles in carbon fiber composite>
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 protrusions>
The carbon fiber composite was observed with a TEM, and the number of protrusions protruding in the substantially radial direction of the carbon fiber observed at a length of 500 nm of a representative portion of the carbon fiber composite surface was counted. The size of the shape portion is obtained by image analysis software and converted into a circle equivalent area (S _PA ). Also measured the diameter of the carbon fiber composite, to calculate the surface area of the assumed side a cylindrical (S _C). From these values obtained, the surface coverage was determined by the following formula.

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

<Protruding part fracture test of carbon fiber composite>
A carbon fiber composite was added to 100 ml of toluene in a vial with a lid at a rate of 10 to 100 μg / ml to prepare a dispersion sample of the carbon fiber composite.

  Using the ultrasonic cleaning device (trade name: USK-3, manufactured by SND Co., Ltd.) having a transmission frequency of 38 kHz and an output of 150 w, the ultrasonic wave was applied to the carbon fiber composite dispersion sample thus obtained. After 60 minutes from the application of ultrasonic waves, the carbon fiber composite is sampled from the dispersion liquid sample, dropped onto the mesh, the sample is prepared, and the TEM is observed for destruction. did.

[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.

[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 FIGS.

[Example 3] Application of organometallic compound (second step)
10 g of titanium tetraisopropoxide (manufactured by Kanto Chemical Co., Inc.) was diluted with 200 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] Binder application (third step)
Immersion treatment for 30 minutes in a solution prepared by diluting 4.0 g of a 60% phenol resin solution with 200 ml of methanol separately from 10 g of the carbon fiber structure intermediate obtained after dipping and drying obtained in Example 3 And then dried at 100 ° C. for 12 hours.

[Example 5] Annealing treatment (fourth step)
The intermediate body 10 g of the three-dimensional network-like carbon fiber structure after immersion and drying obtained in Example 4 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 after the annealing treatment contained 8% Ti. FIG. 4 shows an FE-SEM photograph of the carbon fiber composite having protrusions formed on the surface. Further, FIG. 5 shows a TEM photograph of the carbon fiber composite in which the multi-layer graphene layer (TiC fine particle inclusion) forming the protruding portion is formed. In addition, the multilayer graphene layer (hollow) is formed on the surface of the carbon fiber structure during the annealing process, and the TiC fine particles sandwiched between the multilayer graphene layers of the protrusions are detached and become hollow. A TEM photograph of is shown in FIG. 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.

Further, the R value (I _D / I _G ) measured by Raman spectroscopy (manufactured by Jobin Yvon LabRam HR-800-Horiba) was 0.15.

In addition, the carbon fiber structure in the obtained carbon fiber composite had a circle-equivalent average 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 carbon fiber structure granular part in the carbon fiber composite 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.

  Moreover, when the protrusion part destruction test of the carbon fiber composite was performed according to the above-described procedure, the destruction of the graphene sheet of the protrusion part was not observed, and the protrusion part was stably formed on the surface of the carbon fiber structure. It became clear.

Example 6 Second Step + Boron Compound, Third Step After dissolving 5.0 g of B ₂ O ₃ (manufactured by High Purity Chemical Laboratory Co., Ltd.) in 400 ml of ethanol, titanium tetraisopropoxide (Kanto) 20 g of Chemical Co., Ltd.) was added dropwise and mixed to obtain an immersion liquid. 10 g of the intermediate body of the three-dimensional network-like carbon fiber structure obtained in Example 1 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 soaking and drying is separately added to a solution prepared by diluting 4.0 g of a 60% phenol resin solution with 200 ml of methanol and soaking for 30 minutes. After the treatment, the organic solvent was dried at 100 ° C. for 12 hours.

[Example 7] Annealing treatment (fourth step)
10 g of the three-dimensional network-like carbon fiber structure after immersion and drying obtained in Example 6 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 13.0% Ti. Separately, TiC and TiB (or TiB ₂ ) were detected using an X-ray diffraction measurement apparatus JEOLJDX-3532 (manufactured by JEOL Ltd.).

[Example 8] Molded body preparation example The intermediate body 9g of the three-dimensional network-like carbon fiber structure after immersion and drying obtained in Example 4 was heated at 150 ° C for 30 minutes using a hot press machine. Pressed for a while to obtain a molded body. The obtained molded body had a mass of 8.8 g, a diameter of 40 mm, a height of 23 mm, and a density of 0.3 g / cm ³ .

[Example 9] Annealing treatment for preparing a preform (fourth step)
8.8 g of the three-dimensional network-like carbon fiber structure intermediate formed in Example 8 was annealed at 2500 ° C. for 20 minutes. The finally obtained carbon fiber composite preform on the three-dimensional network after the annealing treatment had a mass of 6.87 g, a height of 24 mm, and a density of 0.23 g / cm ³ . The preform of the three-dimensional network-like carbon fiber composite 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 preform of the carbon fiber composite contained 8.0% Ti. Separately, TiC was detected using an X-ray diffraction measurement apparatus JEOLJDX-3532 (manufactured by JEOL Ltd.) (see FIG. 7).

[Example 10] Annealing after forming a molded body (fourth step)
8.0 g of the three-dimensional network-like carbon fiber structure after immersion and drying obtained in Example 6 was hot-pressed at 150 ° C. for 30 minutes using a hot press machine to obtain a molded body. It was. The obtained molded body had a mass of 7.7 g, a diameter of 40 mm, a height of 7.5 mm, and a density of 0.81 g / cm ³ . The obtained three-dimensional network-like carbon fiber structure intermediate compact was heated at 900 ° C. for 20 minutes and then annealed at 2400 ° C. for 20 minutes. The finally obtained three-dimensional network-like carbon fiber composite preform after the annealing treatment had a mass of 5.33 g, a diameter of 40 mm, a height of 14 mm, and a density of 0.30 g / cm ³ . The preform of the obtained three-dimensional network-like carbon fiber composite 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 preform of the carbon fiber composite contained 12.7% Ti. Separately, TiC and titanium boride (TiB and / or TiB ₂ ) were detected using an X-ray diffractometer JEOLJDX-3532 (manufactured by JEOL Ltd.).

  The graphene layer forming the protrusions on the surface of the carbon fiber composite of the present invention is stable even at a temperature of 3000 ° C. or higher, so that a surface modification effect of high durability against high temperatures is obtained. It is done. In addition, the carbon fiber composite has a graphene layer composed of one or a plurality of layers forming a protruding portion on the surface thereof, and the surface of the carbon fiber (carbon nanotube) as a main part and a part thereof has a crystal structure. Since it can be integrated, the bond with the carbon nanotubes is strong and the protrusions are formed, so in the composite material finally produced using this carbon fiber composite, the anchor effect of the protrusions This strengthens the adhesion between the carbon fiber composite and the matrix. Furthermore, the graphene layer composed of one or more layers forming the protrusions on the surface of the carbon fiber composite has no adverse effect on the structure of the carbon nanotubes. There is no risk of deterioration of physical properties. Further, in the carbon fiber composite of the present invention, the basic carbon fiber 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 carbon. In a mode in which a plurality of fibers are extended, the carbon fiber has a granular portion that has a particle size larger than the outer diameter of the carbon fiber and couples the carbon fibers to each other, and the granular portion is formed during the growth process of the carbon fiber Since the carbon fiber composite of the present invention is formed in a three-dimensional network form, when the composite material is finally manufactured, its thermal conductivity, electrical conductivity, and mechanical strength are It will be good. Moreover, the process for providing a three-dimensional structure later is unnecessary. The fine metal particles that the carbon fiber composite has on its surface act as a graphitization catalyst for the carbon compound. The carbon fiber composite of the present invention is a composite having excellent characteristics when suitably combined with various matrix materials such as metals and ceramics other than metals, rubber, synthetic resins, and carbon-based materials as matrix materials. It is.

  Although it does not specifically limit as a specific example of the utilization use of the carbon fiber composite_body | complex of this invention, For example, the following can be mentioned. (1) As a structural material utilizing mechanical strength. (2) 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. (3) Electromagnetic wave shielding materials, (4) Appliances, vehicles, aircraft bodies, machines housings, battery pole materials, etc. that use physical properties.

It is the process schematic in the manufacturing method of the carbon fiber composite_body | complex 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. It is a FE-SEM photograph of the carbon fiber composite by which fine particles were coat | covered on the surface obtained in the Example of this invention. It is a TEM photograph of the multilayer graphene layer (with TiC fine particles) which forms the projection-like part obtained in the example of the present invention. It is a TEM photograph of the multilayer graphene layer (hollow) which forms the projection-like part obtained in the example of the present invention. 6 is an X-ray diffraction measurement chart of a carbon fiber composite coated with a TiC compound, obtained in another example of the present invention.

Claims (32)

  The carbon fiber is covered with a single-layer or multi-layer graphene layer that forms a protrusion protruding substantially in the radial direction of the carbon fiber, and the single-layer or multi-layer graphene layer serves as a backbone in the protrusion. A carbon fiber composite characterized in that a portion sandwiched between the surfaces of carbon fibers has a structure in which metal fine particles or metal carbide fine particles are included or hollow.   The carbon fiber composite according to claim 1, wherein the surface of the carbon fiber is partially covered with the single-layer or multi-layer graphene layer.   The carbon fiber 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, It has a granular part whose particle size is larger than an outer diameter and couples the carbon fibers to each other, and the granular part is formed in the growth process of the carbon fiber. The carbon fiber composite according to 1 or 2. 4. The carbon fiber composite according to claim 3, wherein the carbon fiber structure described above has an I _D / I _G measured by Raman spectroscopy of 0.2 or more.   The carbon fiber composite according to any one of claims 1 to 4, wherein a part of the one or more layers of the graphene layer and the carbon fiber serving as the backbone are integrated in a crystal structure.   The carbon fiber composite according to any one of claims 1 to 5, wherein a size of each protrusion formed by the one or more layers of the graphene layers is 5 to 70 nm.   Each protrusion-like part formed by the above-described single-layer or multi-layer graphene layer has an average height of 0.05 to 1 times the outer diameter of the carbon fiber serving as the backbone in the substantially radial direction of the carbon fiber. It is a thing, The carbon fiber composite_body | complex of any one of Claims 1-6.   The protruding portion formed by the one or more layers of the graphene layer is formed in a region occupying 1 to 70% of the surface of the carbon fiber. Carbon fiber composite.   The metal species of the metal fine particles 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 according to one.   The carbon fiber composite described above contains 0.001 to 30% by mass of a boron compound in terms of boron with respect to the carbon fiber composite, and the surface of the carbon fiber that serves as the backbone of the single-layer or multilayer graphene layer described above. 10. The carbon fiber according to claim 1, wherein the portion sandwiched between the metal fibers contains metal fine particles, metal carbide or metal boride fine particles, or has a hollow structure. Complex.   The carbon fiber is preformed through a hot press in the course of its manufacturing process, and the surface thereof is coated with a single-layer or multi-layer graphene layer that forms a protrusion protruding substantially in the radial direction of the carbon fiber. The carbon sandwiched between the single-layer or multi-layer graphene layer and the surface of the basic carbon fiber in the protruding portion contains carbon fine particles or metal carbide fine particles, or has a hollow structure. A preform of a fiber composite.   The carbon fiber composite preform according to claim 11, wherein a surface of the carbon fiber is partially covered with the single-layer or multilayer graphene layer.   The carbon fiber 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, It has a granular part whose particle size is larger than an outer diameter and couples the carbon fibers to each other, and the granular part is formed in the growth process of the carbon fiber. A preform of the carbon fiber composite according to 11 or 12. First step of obtaining a carbon fiber intermediate by heating a mixed gas of catalyst and hydrocarbon at a constant temperature of 800 ° C. to 1300 ° C. to grow a carbon material into a fibrous form, Second step of immersing in an organic solvent solution of an organometallic compound or an aqueous solution of a metal salt and a surfactant and then drying the used solvent, and further immersing in an organic solvent solution of a binder and then drying the organic solvent. 3 steps, consisting of a fourth step of heating the carbon fiber intermediate after drying at 800 ° C. to 3000 ° C.,
The surface of the carbon fiber is covered with a single-layer or multi-layer graphene layer that forms a protrusion that protrudes substantially in the radial direction of the carbon fiber, and the single-layer or multi-layer graphene layer serves as a backbone in the protrusion. A method for producing a carbon fiber composite characterized in that a portion sandwiched between carbon fiber surfaces has a structure in which metal fine particles or metal carbide fine particles are included or hollow.   The said 4th process heats the intermediate body of the carbon fiber after drying to 800 to 1500 degreeC, and then anneals at 1500 to 3000 degreeC, The manufacture of the carbon fiber composite_body | complex of Claim 14 Method. 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 A second step of drying an organic solvent solution or an aqueous solution of a metal salt and a surfactant and then drying the solvent used, and a third step of drying the organic solvent after being immersed in an organic solvent solution of a binder and drying It consists of the 4th process of heating the intermediate body of a later carbon fiber structure at 800 ° C-3000 ° C,
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 granular part having a large particle size and bonding the carbon fibers to each other, and the granular part being formed in the growth process of the carbon fiber, The carbon fiber constituting the fiber structure is covered with a single-layer or multi-layer graphene layer that forms a protrusion that protrudes substantially in the radial direction of the carbon fiber. The part sandwiched between the surfaces has a structure in which metal fine particles or metal carbide fine particles are encapsulated or hollow. .   The carbon fiber composite according to claim 16, wherein in the fourth step, the carbon fiber intermediate after drying is heated to 800 ° C to 1500 ° C and then annealed at 1500 ° C to 3000 ° C. Method. 18. The method for producing a carbon fiber composite according to claim 16, wherein the carbon fiber structure has an I _D / I _G measured by Raman spectroscopy of 0.2 or more.   The carbon fiber composite according to any one of claims 14 to 18, wherein a part of the single-layer or multi-layer graphene layer and the carbon fiber serving as a backbone are integrated in a crystal structure thereof. Production method.   The method for producing a carbon fiber composite according to any one of claims 14 to 19, wherein a size of each protrusion formed by the one or more layers of the graphene layers is 5 to 70 nm.   Each protrusion-like part formed by the above-described single-layer or multi-layer graphene layer has an average height of 0.05 to 1 times the outer diameter of the carbon fiber serving as the backbone in the substantially radial direction of the carbon fiber. The method for producing a carbon fiber composite according to any one of claims 14 to 20.   The projecting portion formed by the one or more layers of the graphene layer is formed in a region occupying 1 to 70% of the surface of the carbon fiber. A method for producing a carbon fiber composite.   A preliminary annealing treatment step for heating the carbon fiber intermediate or carbon fiber structure intermediate obtained in the first step to 800 to 1200 ° C. is added between the first step and the second step. The method for producing a carbon fiber composite according to any one of claims 14 to 22, wherein:   The method for producing a carbon fiber composite according to any one of claims 14 to 23, wherein the second step and the third step are performed simultaneously.   The method for producing a carbon fiber composite according to any one of claims 14 to 23, wherein the third step is performed before the second step.   The metal species of the metal fine particles or metal carbide described above is one or two or more selected from Ti, V, Cr, Zr, Nb, Mo, Ta, W, and Y. The manufacturing method of the carbon fiber composite as described in one.   27. The method for producing a carbon fiber composite according to any one of claims 14 to 26, wherein the organometallic compound is a metal alkoxide, a metal acetylacetonate, or a metal fatty acid salt.   In the second step, the organic solvent solution or metal salt of the organic metal compound or the aqueous solution of the surfactant and the aqueous solution of the boron compound is mixed with the organic solvent solution or the aqueous solution of the boron compound, so that the carbon fiber composite described above is mixed. On the other hand, a portion containing 0.001 to 30% by mass of a boron compound in terms of boron and sandwiched between the one or more layers of the graphene layer and the surface of the carbon fiber serving as a base is a metal fine particle, a metal carbide or 28. The method for producing a carbon fiber composite according to any one of claims 14 to 27, wherein the metal boride fine particles are included or have a hollow structure. In the manufacturing method of the carbon fiber composite_body | complex of Claim 14, the carbon fiber which passed through the 2nd process and the 3rd process is hot-pressed at 100 to 200 degreeC, and the obtained carbon fiber molded object is 800 degreeC. Consisting of a fourth step of heating at ~ 3000 ° C,
The surface of the carbon fiber is covered with a single-layer or multi-layer graphene layer that forms a protrusion that protrudes substantially in the radial direction of the carbon fiber, and the carbon fiber surface that forms the basis of the single-layer or multi-layer graphene layer in the protrusion A method for producing a preform of a carbon fiber composite, wherein the portion sandwiched between the metal fibers contains metal fine particles or metal carbide fine particles or has a hollow structure.   30. The carbon fiber composite preliminary assembly according to claim 29, wherein the fourth step is to heat the carbon fiber intermediate after drying to 800 ° C. to 1500 ° C., and then to anneal at 1500 ° C. to 3000 ° C. Manufacturing method of a molded object. The method for producing a carbon fiber composite according to claim 16, 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 second step and the third step. The 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 the carbon fiber The carbon fiber structure formed in the growth process is hot pressed at 100 ° C. to 200 ° C., and the resulting carbon fiber structure molded body is heated at 800 ° C. to 3000 ° C. Consisting of processes,
The surface of the carbon fiber structure is covered with a single-layer or multi-layer graphene layer that forms a protrusion that protrudes substantially in the radial direction of the carbon fiber that constitutes the carbon fiber structure. The portion sandwiched between the graphene layer and the surface of the carbon fiber serving as the backbone contains a metal fine particle or metal carbide fine particle, or has a hollow structure. Production method.   The preliminary carbon fiber composite according to claim 31, wherein in the fourth step, the carbon fiber intermediate after drying is heated to 800 ° C to 1500 ° C and then annealed at 1500 ° C to 3000 ° C. Manufacturing method of a molded object.