WO2007049748A1

WO2007049748A1 - Composite material

Info

Publication number: WO2007049748A1
Application number: PCT/JP2006/321506
Authority: WO
Inventors: Takayuki Tsukada; Jiayi Shan; Jin Chen
Original assignee: Bussan Nanotech Research Institute Inc.
Priority date: 2005-10-28
Filing date: 2006-10-27
Publication date: 2007-05-03
Also published as: JP2007119647A

Abstract

A composite material containing carbon fiber structures of a novel structure which have properties desirable for fillers for composite materials and, when added in a small amount, can improve physical properties including electrical properties, mechanical properties, and thermal properties without impairing the properties of the matrix. The carbon fiber structures each has a three-dimensional network form constituted of carbon fibers with an outer diameter of 15-100 nm and has a granular part which bonds the carbon fibers to one another and from which the carbon fibers project, the granular part having been formed in the course of growth of the carbon fibers. The carbon fiber structures contain boron. The composite material is obtained by incorporating the carbon fiber structures into a matrix in an amount of 0.001-30 mass% based on the whole composition.

Description

Specification

Composite material

Technical field

[0001] The present invention relates to a novel composite material. More specifically, the present invention relates to a composite material having a tough special structure with flexibility and high strength in a matrix and further containing a fine carbon fiber structure containing boron.

Background art

[0002] Materials cannot be obtained with a single material but are combined to obtain characteristics. Conventionally, glass fiber reinforced plastic has been widely used as a composite material, but since carbon fiber was developed and carbon fiber reinforced fiber reinforced plastic (CFRP) was developed, composite materials became particularly popular. It was.

[0003] These materials have been widely used in sporting goods and the like, and have come to be noticed as lightweight and high strength 'high elastic modulus structural materials for aircraft. Later, composite materials included not only fiber reinforced materials but also fine particle reinforced materials. In addition to structural materials where strength and heat resistance are important, functional materials that focus on electrical / electronic properties, optical properties, and chemical properties are also treated as composite materials!

[0004] On the other hand, with the widespread use of electronic devices, troubles such as radio wave interference in which peripheral devices are affected by noise generated from electronic components and malfunctions due to static electricity have become serious problems. In order to solve these problems, a material having excellent conductivity and braking performance is required in this field.

Conventionally, in a polymer material with poor conductivity, a conductive polymer material imparted with a conductivity function by blending a highly conductive filler is widely used. As the conductive filler, metal fiber and metal powder, carbon black, carbon fiber, etc. are generally used. However, when the metal fiber and metal powder are used as a conductive filler, the corrosion resistance is poor and the mechanical strength is low. There is a disadvantage that it is difficult to obtain. On the other hand, when carbon fiber is used as a conductive filler, desired strength and elastic modulus can be achieved by blending a certain amount of general reinforcing carbon fiber. However, it does not become sufficient, and high filling is required to obtain the desired conductivity, so that the original physical properties of the original resin are reduced. In addition, in the case of carbon fibers, when the same amount of fibers is added to the finer fiber diameter, the contact area between the matrix resin and the fibers is increased, so that it is expected to be excellent in conductivity imparting effect.

[0005] Carbon fibers are currently precursor organic polymers, particularly cellulose or polyacrylonitrile, under carefully maintained tensile forces to ensure good orientation of the anisotropic sheet of carbon atoms in the final filament. It is manufactured by pyrolyzing the continuous filaments under control, and becomes expensive due to the weight loss in carbonization and slow carbonization rate.

[0006] Further, in recent years, attention has been focused on fine carbon fibers such as carbon nanostructures represented by carbon nanotubes (hereinafter also referred to as “CNT”) as another carbon fiber.

The graphite layer constituting the carbon nanostructure is a substance having a regular, six-membered ring arrangement structure, and chemically, mechanically and thermally stable properties as well as its unique electrical properties. Therefore, for example, by dispersing and dispersing such fine carbon fibers in solid materials such as various types of resin, ceramics, and metals, or liquid materials such as fuel oil and lubricant, the above-described physical properties can be obtained. If it can be utilized, its use as an additive is expected.

[0007] However, on the other hand, such fine carbon fibers are already agglomerated at the time of production, and if they are used as they are, there is a possibility that dispersion will not progress in the matrix and performance may be deteriorated. is there. Therefore, when trying to exhibit predetermined characteristics such as conductivity in a matrix such as resin, a considerable amount of addition is required.

[0008] Patent Document 1 describes an aggregate in which carbon fibrils having a diameter of 3.5 to 70 nm are entangled with each other, and the longest diameter is 0.25 mm or less and the diameter is 0.10 to 0.25 mm. A rosin composition containing is disclosed. As is clear from the description of Examples and the like in Patent Document 1, numerical values such as the longest diameter and diameter of the carbon fibril aggregate are characteristic values of the aggregate before blending with the coconut oil. Further, Patent Document 2 is an aggregate of carbon fibers having a diameter of 50 to 5000 nm, and the contact between the fibers is fixed by carbonaceous carbide. A composite comprising a carbon fiber material mainly composed of a structure having a size of 5 μm to 500 μm in a matrix is disclosed. Also in this Patent Document 2, the numerical values such as the size of the structure are characteristic values before blending with the fat.

[0009] By using such a carbon fiber aggregate, an improvement in dispersibility in the resin matrix is expected to some extent as compared with the case of mixing in a larger lump. However, the agglomerate described in Patent Document 1 is a force obtained by dispersing carbon fibrils by applying a shearing force with a vibrating ball mill or the like. Additives that improve conductivity and other properties that improve efficiency are still unsatisfactory. In the carbon fiber structure shown in Patent Document 2, the contact points between the fibers are fixed in a state where the carbon fiber aggregates are compression-molded to form the contact points between the fibers after the carbon fibers are manufactured. It is formed by carbonizing residual organic matter such as pitch or organic matter added as a binder that remains on the carbon fiber surface after heat treatment. The electrical characteristics of the film were not very good. Therefore, when it is blended in a matrix such as rosin, its contact point is easily dissociated, so that the shape of the structure cannot be maintained. For example, good electrical characteristics can be obtained by adding a small amount. It has been difficult to form a good conductive path in the matrix. Furthermore, when carbonization is performed by adding a binder or the like to fix the contact point, it is difficult to attach the noda etc. only to the contact point part, and it adheres to the entire fiber. In this case, the fiber diameter was large as a whole and the surface characteristics were inferior, and there was a high possibility that it would not be obtained.

[0010] By the way, when imparting conductivity by blending carbon fibers in a matrix such as resin, a technique of containing boron in the carbon fiber crystals is known (for example, Patent Document 3). . The aim of this technology is to improve the crystallinity of the carbon fiber by incorporating boron into the crystal of the carbon fiber, and to control the electronic state by appropriately generating defects, thereby improving the conductive characteristics. It is.

However, for the same reason as described above, it is difficult for the carbon fiber disclosed in Patent Document 3 to form a good conductive path in the matrix. It was.

Patent Document 1: Japanese Patent No. 2862578

Patent Document 2: JP 2004-119386 A

Patent Document 3: Japanese Patent Application Laid-Open No. 2004-3097

Disclosure of the invention

Problems to be solved by the invention

[0012] The present invention has novel physical properties as a composite material filler, and can improve physical properties such as electrical properties, mechanical properties, thermal properties, etc., without damaging the properties of the matrix, with a small amount of addition. The present invention provides a composite material including a carbon fiber structure having a unique structure.

Means for solving the problem

[0013] In order to solve the above-mentioned problems, the present inventors have intensively studied, and in order to achieve a sufficient improvement in characteristics even if the addition amount is small, the finest possible carbon fiber is used. In addition, these carbon fibers are firmly bonded to each other without being separated and are held in a matrix with a sparse structure, and each carbon fiber itself has as few defects as possible. It has been found that it is effective to change the electronic state by incorporating boron, and the present invention has been achieved.

[0014] That is, the present invention for solving the above problems has a three-dimensional network shape in which a carbon fiber force having an outer diameter of 15 to: LOOnm is also formed, and the carbon fiber structure has a plurality of carbon fibers extending. In this embodiment, the carbon fiber has 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, and further contains fluorine. The composite material is characterized in that the carbon fiber structure is contained in the matrix in a ratio of 0.001 to 30% by mass of the total.

[0015] The present invention also shows the composite material, wherein the boron content is 0.001-2. 1% by mass with respect to the carbon fiber structure.

[0016] The present invention also shows the composite material, wherein the carbon fiber structure has an area-based circle-equivalent mean diameter of 50 to: LOO / zm.

[0017] The present invention further shows the composite material, wherein the carbon fiber structure has a bulk density of 0.0001 to 0.05 gZcm ³ . [0018] In the present invention, the carbon fiber structure is measured by Raman spectroscopy.

D Λ force ^ G

2 to: the composite material described above, characterized in that it is L 4 and I / 1 is 0.25-0.75

G 'G

Charge.

[0019] The present invention also provides the composite material, wherein the carbon fiber structure has a combustion start temperature in air of 700 ° C or higher.

[0020] The present invention also shows the composite material described above, wherein a particle size of the granular portion is larger than an outer diameter of the carbon fiber at the bonded portion of the carbon fiber.

[0021] The present invention also shows the composite material, wherein the carbon fiber structure is produced using at least two or more carbon compounds having different decomposition temperatures as a carbon source. .

[0022] The present invention also shows the above composite material in which the matrix contains an organic polymer.

[0023] The present invention also shows the above composite material in which the matrix contains an inorganic material.

[0024] The present invention also shows the above composite material in which the matrix includes a metal.

[0025] The present invention also includes that the matrix further includes at least one filler selected from the group of metal fine particles, silica, calcium carbonate, magnesium carbonate, carbon black, glass fiber and carbon fiber strength. The composite material as described above is shown. The invention's effect

[0026] In the present invention, the carbon fiber structure is made up of fine carbon fibers arranged in a three-dimensional network as described above by the granular parts formed in the carbon fiber growth process. The carbon fiber structure has a sparse structure when blended in a matrix such as greaves because it has a shape in which a plurality of the carbon fibers extend from the granular part. Even when added in a small amount, the fine carbon fibers can be evenly spread in the matrix.

[0027] Further, in the present invention, since the carbon fiber structure contains boron, each of the carbon fibers and the granular portion can be made of a highly crystalline carbon fiber. And change the electronic state.

[0028] Further, since boron is contained, the removal of the catalytic metal is promoted, and a carbon fiber structure having a low metal content and a small amount of impurities can be obtained.

[0029] Thus, in the composite material according to the present invention, a carbon fiber structure having a fine and high crystallinity in the entire matrix can be obtained by arranging a relatively small amount of the above-described carbon fiber structure. Since the body is uniformly distributed, for example, in terms of electrical characteristics, a good conductive path can be formed in the entire matrix, and the electrical conductivity can be improved. In addition, the filler can be evenly distributed throughout the matrix, and the characteristics can be improved. Therefore, according to the present invention, a composite material useful as a functional material excellent in electrical conductivity, radio wave shielding property, thermal conductivity, etc., a structural material having high strength, etc. can be obtained.

Brief Description of Drawings

FIG. 1 is an SEM photograph of an intermediate of a carbon fiber structure used for a composite material of the present invention.

FIG. 2 is a TEM photograph of an intermediate of a carbon fiber structure used in the composite material of the present invention.

[Figure 3A]

[FIG. 3B] is a TEM photograph of an intermediate of the carbon fiber structure used in the composite material of the present invention.

FIG. 4 is an SEM photograph of a carbon fiber structure used in the composite material of the present invention.

FIG. 5 is an SEM photograph of a carbon fiber structure used in the composite material of the present invention.

FIG. 6 is a drawing showing a schematic configuration of a production furnace used for producing a carbon fiber structure in an example of the present invention.

Explanation of symbols

[0031] 1 Generation furnace

2 Introduction nozzle

3 Collision

4 Source gas supply port

a Inner nozzle inner diameter

b Inner diameter of the generating furnace c Inner diameter of collision part

d Distance from the top of the generator to the raw material gas inlet

e Raw material mixed gas introduction loca Distance to the bottom of the collision part

f Distance from the raw material gas inlet to the bottom of the generator

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail based on preferred embodiments.

The composite material of the present invention is characterized in that a three-dimensional network-like carbon fiber structure having a predetermined structure as described later is contained in a matrix in a ratio of 0.001 to 30% by mass. is there.

[0033] The carbon fiber structure used in the present invention has, for example, a three-dimensional network shape in which a carbon fiber force having an outer diameter of 15 to LOONm is also formed, as seen in the TEM photographs shown in FIGS. 3A and 3B. It is a carbon fiber structure, Comprising: The said carbon fiber structure has the granule part which couple | bonds the said carbon fiber mutually in the aspect with which the said carbon fiber extends in multiple numbers. The carbon fiber structure used in the present invention is a carbon fiber structure characterized by further containing boron in the carbon fiber structure shown in FIGS. 3A and 3B.

[0034] The carbon fiber constituting the carbon fiber structure has an outer diameter in the range of 15 to LOONm. When the outer diameter is less than 15 nm, the carbon fiber has a polygonal cross section as described later. However, on the other hand, the smaller the diameter of the carbon fiber, the greater the number per unit amount, and the longer the length of the carbon fiber in the axial direction and the higher the electrical conductivity, so that the outer diameter exceeding lOOnm can be obtained. It is because it is not suitable as a carbon fiber structure arranged as a modifier or additive in a matrix such as rosin. The outer diameter of the carbon fiber is particularly desirable because it is in the range of 20 to 70 nm. In this outer diameter range, cylindrical graph sheets laminated in the direction perpendicular to the axis, that is, multi-layered, are given the ability to return to their original shape even after deformation, ie they are difficult to bend. Therefore, even after the carbon fiber structure is compressed, it is easy to adopt a sparse structure after being arranged in a matrix such as rosin.

[0035] Note that when annealing is performed at 2400 ° C or higher, the surface spacing of the laminated graph sheets is narrow. The true density increases from 1.89 g / cm ³ to 2. lg / cm ³ , and the carbon fiber has a polygonal cross section perpendicular to the axis. Flexural rigidity (EI) is improved because it is dense and has few defects in both directions of the surface of the graph-like sheet.

[0036] It is desirable that the fine carbon fiber has an outer diameter that changes along the axial direction. If the outer diameter of the carbon fiber is constant and changes along the axial direction in this way, it is considered that a kind of anchor effect is produced in the carbon fiber in a matrix such as greaves. As a result, the dispersion stability increases.

[0037] And, in the carbon fiber structure according to the present invention, fine carbon fibers having such a predetermined outer diameter exist in a three-dimensional network, and these carbon fibers are grown on the carbon fibers. In the process, the granular portions formed in this manner are bonded to each other, and a plurality of the carbon fibers extend from the granular portions. In this way, the fine carbon fibers are simply entangled with each other, and they are bonded to each other in a granular part that is not solid, so that they are firmly bonded to each other. In this case, the structure can be dispersed and blended in the matrix as a bulky structure without being dispersed as a single carbon fiber. Further, in the carbon fiber structure according to the present invention, the carbon fibers are bonded to each other by the granular portion formed in the growth process of the carbon fiber. For example, the electrical resistance value measured at a constant compression density indicates that the mere entanglement of fine carbon fibers, or the junction between the fine carbon fibers after the synthesis of the carbon fibers. Compared with the value of the structure or the like formed by the substance or its carbide, it shows a very low value, and when dispersed and blended in the matrix, a good conductive path can be formed.

[0038] 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 it is not clear exactly. Appears to contain a mixed state of sp ² and sp ³ bonds. After 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 having carbon atomic force are bonded together, and thereafter After the high temperature heat treatment, as shown in FIGS. 3A and 3B, 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. To be. In the carbon fiber structure according to the present invention, between the granular portion and the fine carbon fiber, the graphene layer constituting the granular portion as described above is continuous with the graphene layer constituting the fine carbon fiber. Symbolized by the carbon crystal structure bond (at least a part of the bond is formed, thereby forming a strong bond between the granular portion and the fine carbon fiber. It is what.

[0039] In the present specification, the term "extends carbon fiber force from the granular part" means that the granular part and the carbon fiber are merely apparently formed by other binder (including carbonaceous material). It is not meant to indicate a connected state, but mainly means a state of being connected by a carbon crystal structural bond as described above!

[0040] Further, as described above, the granular part is formed in the growth process of the carbon fiber. As a trace, at least one catalyst particle or the catalyst particle is subjected to a subsequent heat treatment inside the granular part. In the process, there are vacancies generated by volatilization and removal. These pores (or catalyst particles) are essentially independent of the hollow portion formed inside each fine carbon fiber extending from the granular portion (note that only a small part is incidental) Some of them are connected to the hollow part;).

[0041] The number of catalyst particles or pores is not particularly limited, but there are about 1 to about LOOO, more preferably about 3 to 500 per granular part. By forming the granular portion in the presence of such a number of catalyst particles, it is possible to obtain a granular portion having a desired size as described later.

[0042] The size of each catalyst particle or hole existing in the granular part is, for example, 1 to: LOOnm, more preferably 2 to 40 nm, and still more preferably 3 to 15 nm. .

[0043] Further, although not particularly limited, it is desirable that the particle diameter of the granular portion is larger than the outer diameter of the fine carbon fiber as shown in FIG. Specifically, for example, the outer diameter of the fine carbon fiber is 1.3 to 250 times, more preferably 1.5 to: LOO times, and further preferably 2.0 to 25 times. In addition, the said value is an average value. In this way, the particle size of the granular part, which is the bonding point between the carbon fibers, is sufficiently large, 1.3 times the outer diameter of the fine carbon fiber. When the carbon fiber structure is arranged in a matrix such as greaves, a certain amount of elasticity is applied to the carbon fiber extending from the granular part. Even in this case, it can be distributed in the matrix while maintaining the 3D network structure. 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 the 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.

[0044] The specific particle size of the granular portion is a force that depends on the size of the carbon fiber structure and the outer diameter of the fine carbon fibers in the carbon fiber structure. For example, the average value is 20 to 5000 nm. It is preferably 25 to 2000 nm, more preferably about 30 to 500 nm.

[0045] Further, since the granular portion is formed in the carbon fiber growth process as described above, it has a relatively spherical shape, and its circularity is 0.2 on average. ~ <1, preferably ί or 0.5 to 0.99, more preferably ί or about 0.7 to 0.98.

[0046] As described above, the granular portion is formed in the carbon fiber growth process, and for example, the carbonaceous material is formed after the carbon fiber is synthesized at the junction between the fine carbon fibers. In addition, the bonding between the carbon fibers in the granular portion is very strong compared to a structure or the like attached by the carbide, and the carbon fiber breaks in the carbon fiber structure. Even below, this granular part (joint part) is kept stable. Specifically, for example, as shown in Examples described later, the carbon fiber structure is dispersed in a liquid medium, and an ultrasonic wave with a predetermined output and a predetermined frequency is applied to the carbon fiber structure, so that the average length of the carbon fibers is almost halved. Even under such a load condition, the change rate of the average particle diameter of the granular part is less than 10%, more preferably less than 5%, and the granular part, that is, the bonded part of the fibers is stably held. It is what.

[0047] Furthermore, since the carbon fiber structure used in the present invention contains boron, each carbon fiber can be made into a carbon fiber with high crystallinity. In the present invention, the phrase “boron is contained in the carbon fiber structure” refers only to a state in which a part of carbon atoms in the carbon fiber and the granular part constituting the carbon fiber structure are substituted with boron. Not including the state in which boron is attached to the surface.

[0048] Regarding a method for doping (doping) boron into the carbon fiber structure, the present invention is not particularly limited. For example, the carbon fiber structure is only heat treated at a low temperature (eg, 1500 ° C or less). The crystal is still developed, and the carbon fiber in the state is further heat-treated, and the carbon fiber in the (azugroun) state and boron (including boron compound) are mixed, and then graphitized at a high temperature. By carrying out (annealing treatment), boron can be contained in the carbon fiber structure. It is not impossible to incorporate boron into carbon fibers that have been annealed at temperatures of 1600 ° C or higher, or even 1800 ° C or higher. Boron also acts as a catalyst for promoting crystallization of carbon fibers, and is effective in removing the catalytic metal during annealing. Therefore, it is preferable to contain boron before the annealing treatment. .

[0049] The present invention is not particularly limited as boron contained in the carbon fiber structure. Here, “boron” in the present invention is a concept including not only elemental boron but also boron compounds. As described above, when boron is included in the carbon fiber structure, boron that is not evaporated by decomposition or the like before reaching at least 1600 ° C due to the annealing treatment at a high temperature (for example, 1600 ° C or more). It is necessary to use Examples of boron that satisfies this condition include elemental boron, B 2 O 3, H BO, B C,

2 3 3 4 4

BN etc. can be mentioned.

[0050] The boron content is preferably 0.001-2.1% by mass with respect to the carbon fiber structure, and is particularly preferably 0.01-: L 8% by mass. When the boron content is less than 0.001% by mass, it is difficult to improve the effect of boron content, that is, the crystallinity of the carbon fiber. On the other hand, if the content exceeds 2.1% by mass, it will exceed the solid solution limit, and even if added, the effect will be small and the processing cost will be high. In some cases, the surface of the fiber is covered with a boron compound, which adversely affects conductivity.

[0051] The carbon fiber structure used in the present invention desirably has an area-based circle-equivalent mean diameter of about 50-100 μm, more preferably about 60-90 μm. Here face The product-based circle-equivalent mean diameter is obtained by taking an outline of a carbon fiber structure using an electron microscope, etc., and in this photographed image, the outline of each carbon fiber structure is converted into an appropriate image analysis software such as WinRoof. (Trade name, manufactured by Mitani Shoji Co., Ltd.) is used to obtain the area within the contour, calculate the equivalent circle diameter of each fiber structure, and average it.

[0052] Since it depends on the type of matrix material such as resin to be combined, it may not be applied in all cases, but this circle-equivalent mean diameter is included in the matrix such as resin. If the average equivalent circle diameter is less than 50 m, the electrical conductivity may not be sufficiently exhibited. If it exceeds 100 m, for example, when blended into a matrix by kneading or the like, a large increase in viscosity occurs, making it difficult to mix and disperse or to deteriorate moldability.

[0053] Further, in the carbon fiber structure used in the present invention, as described above, the carbon fibers existing in a three-dimensional network are bonded to each other in the granular portion, and the granular portion force is described above. In a single carbon fiber structure, if there are multiple granular parts that combine carbon fibers to form a three-dimensional network, there is a gap between adjacent granular parts. The average distance is, for example, 0.5 m to 300 m, more preferably 0.5 ^ 100 ^ m, and further preferably about 1 to 50 / ζ πι. The distance between the adjacent granular parts is a distance measured from the central part of one granular body to the central part of the granular part adjacent thereto. If the average distance between the granular materials is less than 0.5 m, the carbon fiber will not be sufficiently developed into a three-dimensional network. For example, when dispersed in a matrix, a good conductive path will be obtained. On the other hand, if the average distance exceeds 300 m, it becomes a factor to increase the viscosity when dispersed and mixed in the matrix, and the carbon fiber structure with respect to the matrix This is because the dispersibility may decrease.

[0054] Further, as described above, in the carbon fiber structure used in the present invention, the carbon fibers existing in a three-dimensional network are bonded to each other in the granular part, and the carbon part is described above. The carbon fiber has a shape in which a plurality of carbon fibers extend, and thus the structure has a bulky structure in which carbon fibers are sparsely present. Specifically, for example, the bulk density is 0.001. It is desirable to be ˜0.05 g / cm ³ , more preferably 0.001-0.02 g / cm ³ . This is because if the bulk density exceeds 0.05 gZcm ³ , it becomes difficult to improve the physical properties of the matrix such as rosin by adding a small amount.

[0055] Further, the carbon fiber structure used in the present invention is such that the carbon fibers existing in a three-dimensional network are bonded to each other in the granular portion formed during the growth process! Therefore, as described above, the force that the electrical characteristics of the structure itself is very excellent, for example, the powder resistance value force measured at a constant compression density of 0.8 gZcm ³ is 0.02 Ω • cm or less. Desirably, it is preferably 0.001-0.010 Ω 'cm. This is because when the powder resistance value exceeds 0.02 Ω'cm, it becomes difficult to form a good conductive path when blended in a matrix such as resin.

[0056] In addition, the carbon fiber structure used in the present invention has high strength and conductivity, and it is desirable that the graph end sheet constituting the carbon fiber contains boron. For example, the ID Λ ratio measured by Raman spectroscopy is

G 0. 2 to 1.

4 and I Zl is preferably 0.25-0.75. Where Raman spectroscopy

G 'G

The analysis, the peak around 1580 cm ^_1 in a large single crystal graphite (G-band) only appear. Crystals by and lattice defects is finite ultrafine sizes, the peak (D band) appears near 1360 cm ^_1. In addition, when the measurement range is expanded, a G 'band appears around 2700cm- ¹ . Therefore, the intensity ratio of D band and G band (R = I / \ = 1 ZI) and G,

1360 1580 D G

If the intensity ratio (I / \ = i Zi) of the band and G band is within the predetermined range as described above,

2700 1580 G 'G

It is also a force considered that boron is contained in the graph end sheet. When boron is contained in the graph ensheet, the G band waveform in Raman spectroscopy becomes asymmetric, and a shoulder is recognized on the high wave number side.

[0057] Further, it is desirable that the carbon fiber structure used in the present invention has a combustion start temperature in air of 700 ° C or higher, more preferably 750 to 900 ° C. As described above, since the graph ensheet of the carbon fiber structure contains boron and the carbon fiber has an intended outer diameter, it has such a high thermal stability. .

[0058] The carbon fiber structure having the desired shape as described above is not particularly limited, and can be prepared, for example, as follows. [0059] Basically, an organic compound such as hydrocarbon is chemically pyrolyzed by CVD using transition metal ultrafine particles as a catalyst to obtain a fiber structure (hereinafter referred to as an intermediate), to which boron or a boron compound is added. Further heat treatment is performed in the mixed state. Boron or a boron compound may be mixed in advance with an organic compound such as hydrocarbon (that is, boron is added before obtaining an intermediate), and further boron is mixed after high-temperature heat treatment. This is also possible.

[0060] As the raw material organic compound, hydrocarbons such as benzene, toluene and xylene, alcohols such as carbon monoxide (CO) and ethanol can be used. Although not particularly limited, in obtaining the fiber structure used in the present invention, it is preferable to use at least two or more carbon compounds having different decomposition temperatures as the carbon source. As used herein, “at least two or more carbon compounds” does not necessarily mean that two or more kinds of raw material organic compounds are used, but a case where one kind of raw material organic compound is used. Even in the process of synthesizing the fiber structure, for example, a reaction such as hydrodealkylation of toluene-xylene occurs, and the subsequent pyrolysis reaction system! It also includes a mode in which two or more carbon compounds having different!

[0061] 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 carbon compound. Therefore, by adjusting the composition ratio of two or more carbon compounds in the raw material gas, a relatively large number of combinations are used as the carbon compounds. be able to.

[0062] 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, Alkenes such as propylene, butylenes, pentenes, heptenes, cyclopentene, etc., especially alkenes having about 1 to 7 carbon atoms; alkynes such as acetylene and propyne, especially alkynes having about 1 to 7 carbon atoms; , Aromatic or heteroaromatic hydrocarbons such as styrene, xylene, naphthalene, methenolenaphthalene, indene, and phenanthrene, especially those having about 6 to 18 carbon atoms. Alcohols such as aromatic or heteroaromatic hydrocarbons, methanol, ethanol, etc., especially alcohols with about 1 to 7 carbon atoms; in addition, two or more types of carbon with selected medium strengths such as carbon monoxide, ketones and ethers Adjust the gas partial pressure so that the compound can exhibit different decomposition temperatures within the desired thermal decomposition reaction temperature range and use them in combination, and Z or the residence time in the specified temperature range The carbon fiber structure according to the present invention can be efficiently produced by optimizing the mixing ratio.

[0063] 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, More preferably, 3 to: LOO is desirable. This value is the gas composition ratio at the inlet 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 what occurs in 1, it is sufficient to supply the shortage of methane separately. For example, if the molar ratio of methane to benzene is 3, add 2 moles of methane to 1 mole of toluene. Note that methane to be added to toluene is not limited to the method of preparing fresh methane separately, but unreacted methane contained in the exhaust gas discharged from the reactor is circulated and used. It is also possible to use it.

[0064] 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 portion and the granular portion are sufficiently developed.

[0065] Note that an inert gas such as argon, helium, xenon, or hydrogen can be used as the atmospheric gas.

[0066] Further, as the catalyst, a mixture of transition metals such as iron, cobalt and molybdenum, transition metal compounds such as iron cene and acetate metal salts, and sulfur compounds such as sulfur, thiophene and iron sulfide is used.

[0067] The synthesis of the intermediate is carried out by using a CVD method such as hydrocarbon, which is usually performed, and evaporating the mixed liquid of hydrocarbon and catalyst as raw materials and introducing hydrogen gas or the like into the reactor as a carrier gas. And pyrolyze at a temperature of 800-1300 ° C. As a result, a plurality of carbon fiber structures (intermediates) having a sparse three-dimensional structure in which the fibers having an outer diameter of 15 to: LOOnm are joined together by granular materials grown using the catalyst particles as nuclei. cm force size of several tens of centimeters Synthesize the aggregate.

[0068] The thermal decomposition reaction of the hydrocarbon as a raw material is mainly produced on the surface of granular particles that are grown using the catalyst particles as a nucleus, and the recrystallization of carbon generated by the decomposition is caused by the catalyst particles or granular materials. By proceeding in a certain direction, it grows in a fibrous form. However, in order to obtain the carbon fiber structure according to the present invention, the tolerance between the thermal decomposition rate and the growth rate is intentionally changed, for example, as described above, the decomposition temperature as a carbon source. By using at least two or more different carbon compounds, the carbon material is grown three-dimensionally around the granular material that does not grow the carbon material only in one-dimensional direction. Of course, the growth of such three-dimensional carbon fibers is not dependent only on the balance between the pyrolysis rate and the growth rate, but the crystal face selectivity of the catalyst particles, the residence time in the reactor, The temperature distribution is also affected, and the balance between the pyrolysis reaction and the growth rate is affected 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 becomes a catalyst particle. Grows in the circumferential direction. Therefore, by intentionally changing the balance between the thermal decomposition rate and the growth rate, the growth direction of the carbon material as described above is made to be a multi-direction under control without making the growth direction constant. Such a three-dimensional structure can be formed. In order to easily form a three-dimensional structure as described above in which the fibers are bonded together by granular materials in the produced intermediate, the composition of the catalyst, the residence time in the reaction furnace, the reaction temperature, and the gas It is desirable to optimize the temperature and the like.

[0069] As a method for efficiently producing the carbon fiber structure according to the present invention, a reactor other than the above-described approach using two or more carbon compounds having different decomposition temperatures at an optimum mixing ratio is used. One approach is to generate turbulent flow in the vicinity of the supply port of the source gas supplied to the tank. The turbulent flow here is a turbulent flow that is a vortex and a flow that rushes.

[0070] In the reaction furnace, metal catalyst fine particles are formed by decomposition of the transition metal compound as a catalyst in the raw material mixed gas immediately after the raw material gas is introduced into the reaction furnace from the supply port. This is brought about through the following steps. That is, first, the transition The metal compound is decomposed into metal atoms, and then cluster formation occurs by collision of a plurality of metal atoms, for example, about 100 atoms. At the stage of this generated cluster, it does not act as a catalyst for fine carbon fibers, and the generated clusters further gather together by collision, resulting in about 3ηπ! It grows to crystalline particles of about lOnm and is used as metal catalyst fine particles for the production of fine carbon fibers.

[0071] In this catalyst formation process, if there is a vortex due to a strong turbulent flow as described above, a more intense collision is possible as compared to a collision between metal atoms or clusters with only Brownian motion, and a collision per unit time. By increasing the number of times, the metal catalyst fine particles can be obtained in a high yield in a short time, and the concentration, temperature, etc. can be made uniform by the vortex flow to obtain metal catalyst fine particles having a uniform particle size. Furthermore, in the process of forming the metal catalyst fine particles, an aggregate of metal catalyst fine particles in which a large number of metal crystalline particles are gathered is formed by vigorous collision due to the vortex. Since the metal catalyst fine particles are generated promptly in this way, the decomposition of the carbon compound is promoted and sufficient carbon material is supplied, and each metal catalyst fine particle of the aggregate is radially formed as a nucleus. On the other hand, if the thermal decomposition rate of some of the carbon compounds is faster than the growth rate of the carbon material as described above, the carbon material also grows in the circumferential direction of the catalyst particles, A granular portion is formed around the aggregate to efficiently form a carbon fiber structure having an intended three-dimensional structure. The aggregate of metal catalyst fine particles may include catalyst fine particles that are less active than other catalyst fine particles or that have been deactivated during the reaction. The non-fibrous or very short fibrous shape that has grown on the surface of such a catalyst fine particle before agglomerating as an aggregate, or has grown with such a catalyst fine particle as a nucleus after becoming an aggregate. This carbon material layer is considered to form the granular part of the carbon fiber structure according to the present invention by being present at the peripheral position of the aggregate.

[0072] In the vicinity of the raw material gas supply port of the reaction furnace, there is no particular limitation on the specific means for generating a turbulent flow in the raw material gas flow. It is possible to adopt a means such as providing some kind of collision part at a position where it can interfere with the flow of the raw material gas led out to. The shape of the collision part is not limited at all. Sufficient turbulent flow is formed in the reactor by the vortex generated from the collision part. However, for example, when a plurality of baffle plates, paddles, taper tubes, umbrellas, and the like having various shapes are used alone or in combination, a plurality of shapes can be adopted.

[0073] In this way, the intermediate obtained by heating the catalyst and hydrocarbon mixed gas at a constant temperature in the range of 800 to 1300 ° C is pasted with patch-like sheet pieces that also contain carbon nuclear power. It has a combined (incomplete, burnt-in) structure, and when subjected to Raman spectroscopic analysis, there are many defects with very large and small G 'bands. Further, the produced intermediate contains unreacted raw material, non-fibrous carbide, tar content and catalytic metal.

In order to remove these residues and obtain the desired carbon fiber structure with few defects, high-temperature heat treatment at 1600 to 3000 ° C is performed by an appropriate method.

[0074] That is, for example, this intermediate is heated at 800 to 1200 ° C to remove volatile components such as unreacted raw materials and tars, and then annealed at a high temperature of 1600 to 3000 ° C. Thus, the desired structure is prepared, and at the same time, the catalyst metal contained in the fiber is removed by evaporation. At this time, in order to protect the material structure, a reducing gas or a trace amount of carbon monoxide or carbon dioxide may be added to the inert gas atmosphere.

[0075] When the intermediate is annealed at a temperature in the range of 1600 to 3000 ° C, the patch-like sheet pieces made of carbon atoms are bonded together to form a plurality of graph-ensheet-like layers.

[0076] In addition, in the stage of performing the high temperature heat treatment, boron can be contained (doped) in the carbon fiber structure by mixing the intermediate and boron. Here, in order to efficiently contain boron in the carbon fiber structure, it is necessary to mix the intermediate and boron well so that they are in uniform contact. For this purpose, it is preferable to use fluorine (or boron compound) particles having the smallest possible particle size. If the particles are large, a high-concentration region is partially generated, which may cause solidification. Specifically, the average particle size of boron is 100 m or less, preferably 50 μm or less, more preferably 20 m or less. When boric acid or the like is used as the boron source, a method of adding a solution and evaporating the solvent in advance or a method of evaporating the solvent during the heating process can be used. If the solution is mixed uniformly, the boron compound will be It can be uniformly attached to the surface.

[0077] Further, before or after such high-temperature heat treatment, a step of crushing the circle-equivalent mean diameter of the carbon fiber structure to several cm, and a circle-equivalent mean diameter of the crushed carbon fiber structure Through a step of pulverizing to 50 to L00 m to obtain a carbon fiber structure having a desired equivalent circular average diameter. In addition, you may perform the grinding | pulverization process which does not pass through a crushing process. Moreover, you may perform the process which granulates the aggregate | assembly which has two or more carbon fiber structures based on this invention in the shape, size, and bulk density which are easy to use. More preferably, in order to effectively utilize the above structure formed during the reaction, annealing is further performed in a state where the bulk density is low (a state in which fibers are stretched as much as possible and a porosity is large). Effective for imparting conductivity to fat.

[0078] The fine carbon fiber structure used in the present invention comprises:

A) Low bulk density,

B) Good dispersibility in matrix such as rosin

C) High conductivity,

D) High thermal conductivity,

E) Good slidability,

F) Good chemical stability,

G) High thermal stability,

And can be used in a wide range as a composite material filler for solid materials such as resin, ceramics, and metals as will be described later, and can be used as a composite material according to the present invention. .

[0079] Next, in the composite material of the present invention, as the matrix for dispersing the carbon fiber structure as described above, an organic polymer, an inorganic material, a metal, or the like can be preferably used, and an organic polymer is most preferable. .

[0080] Examples of the organic polymer include polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyacetal, polyethylene terephthalate, polycarbonate, polyvinyl acetate, polyamide, polyamide imide, polyether imide, polyether ether ketone, polybutyl alcohol, polyphenol. Renether, poly (meth) acrylate and liquid crystal poly Various types of thermoplastic resins such as mer, epoxy resins, bulle ester resins, phenol resins, unsaturated polyester resins, furan resins, imide resins, urethane resins, melamine resins, silicone resins and Various thermosetting resins such as urea resin, natural rubber, styrene 'butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), ethylene' propylene rubber (E PDM), -tolyl rubber (NBR), Various elastomers such as 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 are available. Can be mentioned.

[0081] The organic polymer may be in the form of various compositions such as adhesives, fibers, paints, and inks.

[0082] That is, matrix strength For example, epoxy adhesive, acrylic adhesive, urethane adhesive, phenol adhesive, polyester adhesive, vinyl chloride adhesive, urea adhesive, melamine Adhesives, olefinic adhesives, butyl acetate adhesives, hot melt adhesives, cyanoacrylate adhesives, rubber adhesives and cellulose adhesives, acrylic fibers, acetate fibers, aramid fibers, Fibers such as nylon fiber, novoloid fiber, cellulose fiber, viscose rayon fiber, vinylidene fiber, vinylon fiber, fluorine fiber, polyacetal fiber, polyurethane fiber, polyester fiber, polyethylene fiber, polyvinyl chloride fiber and polypropylene fiber Furthermore, phenolic resin, epoxy resin alkyd resin Fat-based coating, acrylic 榭脂 based paints, unsaturated Poriesu ether-based paints, polyurethane based paints, silicone paints, fluorine 榭脂 based paint, a paint such as a synthetic resin Emarujiyon based paints.

[0083] As the inorganic material, for example, a ceramic material or an inorganic oxide polymer force can be used. Preferred examples include carbon materials such as carbon carbon composites, glass, glass fiber, sheet glass and other molded glass, silicate ceramics and other refractory ceramics such as acid aluminum, carbon carbide, Examples include magnesium oxide, silicon nitride, boron nitride, and zirconium oxide.

[0084] When the matrix is a metal, suitable metals include aluminum, magnesium, lead, copper, tungsten, titanium, niobium, hafnium, vanadium, and combinations thereof. Gold and mixtures are mentioned.

[0085] Further, the composite material of the present invention may contain other fillers in addition to the carbon fiber structure described above. Examples of such fillers include metal fine particles, silica, calcium carbonate. , Magnesium carbonate, carbon black, glass fiber, carbon fiber, and the like. These can be used alone or in combination of two or more.

[0086] The composite material of the present invention includes an effective amount of the above-described carbon fiber structure in the matrix as described above.

The amount is about 0.001% to 30% depending on the application of the composite material and the matrix. If it is less than 001%, the reinforcing effect of strength as a structural material is small, and the electrical conductivity is not sufficient. On the other hand, if it exceeds 30%, the strength decreases, and the adhesion of paints, adhesives, etc. also deteriorates. In the composite material of the present invention, even if the amount of the carbon fiber structure as the filler is relatively low, fine carbon fibers can be arranged in the matrix with a uniform spread, As described above, it is a composite material useful as a functional material having excellent electrical conductivity, radio wave shielding properties, thermal conductivity, etc., high strength, and structural material.

[0087] Furthermore, regarding the composite material according to the present invention, specific examples of the composite material according to the function of the carbon fiber structure to be blended are as follows. Is not to be done.

[0088] 1) Using electrical conductivity

Suitable for use as, for example, packaging materials, gaskets, containers, resistors, conductive fibers, electric wires, adhesives, inks, paints, etc. It is done. The same effect can be expected for composite materials added to inorganic materials, particularly ceramics, metals, etc., in addition to composite materials with greaves.

[0089] 2) Using thermal conductivity

It can be used in the same manner as in the case of using the conductivity.

[0090] 3) Using electromagnetic wave shielding

By mixing it with rosin, it is suitable as an electromagnetic wave shielding paint or molded electromagnetic wave shielding material. [0091] 4) Using physical properties

In order to improve slidability, it is mixed with resin and metal and used for rolls, brake parts, tires, bearings, lubricants, gears, pantographs, etc.

[0092] Further, it can be used for the body of electric wires, home appliances 'vehicles' airplanes, etc., and housings of machines by utilizing its light weight and tough characteristics.

[0093] In addition, it can also be used as a substitute for conventional carbon fibers and beads, and is applied to, for example, battery pole materials, switches, and vibration-proof materials.

[0094] 5) Using filler properties

The fine fibers of the carbon fiber structure have excellent strength, flexibility, and excellent filler characteristics that constitute a network structure. By utilizing this characteristic, it can contribute to the enhancement of the electrodes of the energy devices such as lithium-ion secondary battery, lead-acid battery, capacitor, fuel cell and the improvement of cycle characteristics.

Example

[0095] Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the following examples.

In the following, each physical property value of the carbon fiber structure used in the present invention was measured as follows.

[0096] <Circular equivalent average diameter based on area>

First, take a photograph of the pulverized product with SEM. In the obtained SEM photograph, only the carbon fiber structure with a clear outline was the target, and the carbon fiber structure that was broken was unclear 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. The contour of each carbon fiber structure is traced using image analysis software WinRoof (trade name, manufactured by Mitani Corporation), the area within the contour is obtained, and the equivalent circle diameter of each fiber structure is calculated. This was averaged.

[0097] <Measurement of bulk density>

Fill a transparent cylinder with an inner diameter of 70 mm with lg powder, pressure 0. IMpa, capacity 1.3 liters of air. When it blows out 5 times Measure the height of the powder layer after settling. At this time, the number of measurement locations was assumed to be 6, and the average of the 6 locations was obtained, and then the bulk density was calculated.

[0098] <Raman spectroscopy>

Using a LabRam800 manufactured by Horiba Jobin Yvon, measurement was performed using an argon laser at a wavelength of 514 nm.

Using TG-DTA manufactured by Mac Science, the temperature was increased at a rate of 10 ° CZ while circulating air at a flow rate of 0.1 LZ, and the combustion behavior was measured. During combustion, TG shows a decrease in weight and DTA shows an exothermic peak, so the top position of the exothermic peak was defined as the combustion start temperature.

[0099] <Powder resistance and resilience>

CNT powder lg is weighed, filled and compressed into a resin die (inner dimensions L 40mm, W 10mm, H 80mm), and the displacement and load are read. When a constant current was passed by the 4-terminal method, the voltage at that time was measured, and when the density was measured to 0.9 gZcm ³ , the pressure was released and the density after restoration was measured. For powder resistance, the resistance when compressed to 0.5, 0.8 and 0.9 g / cm ³ shall be measured.

[0100] <Average particle size of granular part, circularity, ratio with fine carbon fiber>

As with the measurement of the circle-based average diameter based on area, first take a picture of the carbon fiber structure with SEM. In the obtained SEM photographs, only the carbon fiber structure with a clear outline was targeted, and those with a collapsed carbon fiber structure were 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.

[0101] For each target carbon fiber structure, the particle part, which is the bonding point between carbon fibers, is regarded as one particle, and its outline is image analysis software WinRoof (trade name, Mitani Corp. The area within the contour was obtained, and the equivalent circle diameter of each granular part was calculated and 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 actual contour length (L) of each granular portion. The degree was obtained and averaged.

[0102] [Equation 1] R = AX 4 TU ZL ²

[0103] Further, the outer diameter of the fine carbon fiber in each of the targeted carbon fiber structures is obtained, and from this and the equivalent circle diameter of the granular portion of each of the carbon fiber structures, the granular portion in each carbon fiber structure Was determined as a ratio to the fine carbon fiber and averaged.

[0104] <Average distance between granular parts>

[0105] In each of the targeted carbon fiber structures, all the portions where the granular portions are connected by the fine carbon fibers are searched, and the distance between the adjacent granular portions connected by the fine carbon fibers in this way (the granularity at one end) Body center force The length of the fine carbon fiber including the center of the granular material at the other end) was measured and averaged.

[0106] <Destructive test of carbon fiber structure>

A carbon fiber structure was added to 100 ml of toluene placed in a vial with a lid at a rate of 30 gZml to prepare a dispersion sample of the carbon fiber structure.

[0107] With respect to the carbon fiber structure dispersion liquid sample thus obtained, an ultrasonic cleaner with a transmission frequency of 38 kHz and an output of 150 w (trade name: USK-3, manufactured by SENUDY Co., Ltd.) Ultrasonic waves were irradiated, and changes in the carbon fiber structure in the dispersion sample were observed over time.

[0108] First, an ultrasonic wave is irradiated, and after a lapse of 30 minutes, a predetermined amount of 2 ml of the dispersion liquid sample is withdrawn from the bottle, and a photograph of the carbon fiber structure in the dispersion liquid is taken with an SEM. 200 fine carbon fibers (fine carbon fibers with at least one end bonded to the granular part) in the carbon fiber structure of the obtained SEM photograph were randomly selected, and each selected fine carbon fiber was selected. The length was measured to determine the D average value, which was used as the initial average fiber length.

50

[0109] On the other hand, 200 granular parts, which are bonding points between carbon fibers in the carbon fiber structure of the obtained SEM photograph, were randomly selected, and each selected granular part was regarded as one particle. The image analysis software WinRoof (trade name, Mitani Trading Co., Ltd.) To obtain the area within the contour, and calculate the equivalent circle diameter of each granular part.

5 Average values were determined. The obtained D average value was used as the initial average diameter of the granular portion.

0 50

[0110] After that, a fixed amount of 2 ml of the dispersion liquid sample was taken out from the bottle at regular time intervals in the same manner as described above, and a photograph of the carbon fiber structure in the dispersion liquid was taken with an SEM. SEM photo D Fine length of carbon fiber in carbon fiber structure and D of granular part

The 50 50 average diameter was determined in the same manner as described above.

[0111] Then, the calculated D average length of fine carbon fibers is about half of the initial average fiber length.

50

The D average diameter of the granular portion at the time (in this example was irradiated with ultrasonic waves and after 500 minutes had elapsed) was compared with the initial average diameter, and the fluctuation ratio (%) was examined.

50

[0112] <Conductivity>

Using a four-point probe type low resistivity meter (Loresta GP, manufactured by Mitsubishi Igaku), measure the resistance (Ω) of the paint film surface at nine locations on the surface of the composite material, and the volume resistivity ( The average value was calculated in terms of Ω'cm).

[0113] <Thermal conductivity>

Cut the test piece into a predetermined shape and measure the thermal conductivity (WZmK) by laser flash method.

[0114] (Example 1)

i) Synthesis of carbon fiber structure

A carbon fiber structure was synthesized using toluene as a raw material by the CVD method.

The catalyst was a mixture of Huekousen and Thiophene, and the reaction was carried out in a hydrogen gas reducing atmosphere. Toluene and catalyst were heated together with hydrogen gas to 380 ° C, supplied to the production furnace, and pyrolyzed at 1250 ° C to obtain a carbon fiber structure (first intermediate).

[0115] Fig. 6 shows a schematic configuration of a generating furnace used when manufacturing this carbon fiber structure (first intermediate). As shown in FIG. 6, the production furnace 1 has a power having an introduction nozzle 2 for introducing a raw material mixed gas composed of toluene, a catalyst and hydrogen gas as described above into the production furnace 1 at its upper end. Further, a cylindrical collision portion 3 is provided outside the introduction nozzle 2. The collision part 3 can interfere with the flow of the raw material gas introduced into the reactor through the raw material gas supply port 4 located at the lower end of the introduction nozzle 2. This fruit In the generating furnace 1 used in the examples, the inner diameter a of the introducing nozzle 2, the inner diameter b of the generating furnace 1, the inner diameter c of the cylindrical collision part 3, the top end of the generating furnace 1 and the raw material mixed gas inlet 4 The distance from the raw material mixed gas inlet 4 to the lower end of the collision part 3, and the distance from the raw material mixed gas inlet 4 to the lower end of the generating furnace 1, f, a: b: c: d: e: f = l. 0: 3.6: 1.8: 3.2: 2.0: 21.0. The feed gas introduction rate into the reactor was 1850 NLZmin and the pressure was 1.03 atm.

[0116] The intermediate synthesized as described above was calcined in nitrogen at 900 ° C to separate hydrocarbons such as tar to obtain a second intermediate. The R value of this second intermediate measured by Raman spectroscopy was 0.98. Figures 1 and 2 show SEM and TEM photographs of this first intermediate dispersed in toluene and observed after preparation of an electron microscope sample.

[0117] Next, the a second intermediate, whereas 0.1 mass ^_0/0 of BO (Wako Chemical Compan

twenty three

y) was uniformly dispersed in ethanol for 20 minutes using ultrasonic waves (KUBOTA UP50H). Thereafter, it was dried under reduced pressure for 24 hours.

[0118] The boron-added second intermediate was heat-treated at 2300 ° C in argon at a high temperature, and the resulting carbon fiber structure aggregate was pulverized by an airflow pulverizer. The carbon fiber structure used was obtained.

[0119] Fig. 4 shows an SEM photograph of the obtained carbon fiber structure dispersed in toluene with ultrasonic waves and observed after preparation of a sample for an electron microscope.

[0120] Fig. 5 shows the SEM photograph of the obtained carbon fiber structure as it is placed on the electron microscope sample holder, and Table 1 shows the particle size distribution.

[0121] The obtained carbon fiber structure had an equivalent circle average diameter of 75.8 m and a bulk density of 0.003.

5g / cm ³ , Raman I / 1 ratio is 0.668, I

D G G '/ \ Ratio value is 0.44, TG combustion temperature is 818 ° C

G

The powder resistance value was 0.0032 Ω'cm, and the density after restoration was 0.33 g / cm ³ .

[0122] Further, the average particle size of the granular portion in the carbon fiber structure was 452 nm (SD208 nm), which was 7.38 times the outer diameter of the fine carbon fiber in the carbon fiber structure.

. The circularity of the granular part was 0.68 (SD 0.14) on average.

[0123] Further, when the carbon fiber structure was subjected to a destructive test according to the procedure described above, the initial average fiber length (D) after 30 minutes of ultrasonic application was 13.0 m. 500 minutes later The average fiber length (D) of 6.8 / zm is almost half of the length, and in the carbon fiber structure

50

It was shown that many cuts occurred in the fine carbon fibers. The average diameter (D) of the granular part 500 minutes after application of ultrasonic waves was compared with the initial initial average diameter (D) 30 minutes after application of ultrasonic waves.

When compared with 50 50, the fluctuation (decrease) rate is only 4.7%, and considering the measurement error, etc., the cut granular part itself does not break even under load conditions where many cuts occur in the fine carbon fiber. It became clear that it functioned as a bonding point between fibers that were hardly destroyed.

[0124] Table 2 summarizes various physical property values of the carbon fiber structure synthesized in Example 1.

[0125] [Table 1]

[0126] [:

ii) Composite material generation

A composite material of the present invention containing the carbon fiber structure of Example 1 synthesized in i) above in the matrix was produced.

Specifically, the carbon fiber structure synthesized in the above i) having the composition shown in Table 3 below was prepared by using an epoxy resin (Adeka Resin, manufactured by Asahi Denka Kogyo Co., Ltd.), a curing agent (Ade force hardener, Asahi Denki). And then kneaded for 10 minutes with a rotating and revolving centrifugal stirrer (Awatori Netaro AR-250, manufactured by Sinky) to produce an epoxy adhesive composition.

[0128] The epoxy adhesive composition obtained here was applied onto a glass plate with an applicator having a coating width of 100 mm and a gap of 200 m, and kept at 170 ° C for 30 minutes to form a cured coating film. Produced. The prepared coating film was cut into a 50 mm square to obtain a test piece. Volume resistivity and thermal conductivity were measured using this test piece. The results are shown in Table 3.

[0129] Further, an epoxy resin film was formed in the same manner so that the content of the carbon fiber structure was 0.5 mass%.

[0130] (Comparative Example 1)

ii) Composite material generation

Instead of carbon fiber structure, contains commercially available carbon black in the matrix

A composite material of Comparative Example 1 was produced.

The specific method is the same as that for producing the composite material in Example 1 except that carbon black is used instead of the carbon fiber structure.

[0131] Using the composite specimen of Comparative Example 1, the volume resistivity and the thermal conductivity were measured. The results are shown in Table 3 together with those of Example 1 above.

[0132] [Table 3]

P-4100E: Asahi Denka Kogyo Co., Ltd., Adeka Resin EP-4100E; Bisphenol A type epoxy resin, epoxy equivalent 190

As is apparent from Table 1 above, volume resistivity and thermal conductivity can be improved by incorporating boron into the carbon fiber structure constituting the composite material.

Claims

The scope of the claims

[I] Outer diameter 15 ~: It has a three-dimensional network configuration that also includes the LOOnm carbon fiber force, and has a granular part that binds the carbon fibers to each other in a manner in which a plurality of the carbon fibers extend. And the granular part is formed in the process of growing the carbon fiber, and the carbon fiber structure containing boron is further added to 0.001 to 30% by mass of the whole. A composite material characterized in that it is contained in the matrix in a proportion of

[2] The composite material according to claim 1, wherein a content of the boron is 0.001 to 2.1% by mass with respect to the carbon fiber structure.

[3] The composite material according to claim 1 or 2, wherein the carbon fiber structure has an area-based circle-equivalent mean diameter of 50 to LOO / zm.

[4] The composite material according to any one of [1] to [3], wherein the carbon fiber structure has a bulk density of 0.0001 to 0.05 gZcm ³ .

[5] The carbon fiber structure is I 2 to 1.4 measured by Raman spectroscopy.

D Λ is 0.

G

And I / \ is 0 · 25-0.75. 1.

G 'G

Composite material described in one.

6. The composite material according to any one of claims 1 to 5, wherein the carbon fiber structure has a combustion start temperature in air of 700 ° C or higher.

[7] The carbon fiber bonding portion according to any one of claims 1 to 6, wherein a particle diameter of the granular portion is larger than an outer diameter of the carbon fiber. Composite material.

[8] The composite according to any one of [1] to [7], wherein the carbon fiber structure is produced using at least two or more carbon compounds having different decomposition temperatures as a carbon source. material.

[9] The composite material according to any one of [1] to [8], wherein the matrix contains an organic polymer.

[10] The composite material according to any one of claims 1 to 8, wherein the matrix contains an inorganic material.

[II] The composite material according to any one of claims 1 to 8, wherein the matrix contains a metal. 12. The matrix further comprises at least one filler selected from the group power consisting of metal fine particles, silica, calcium carbonate, magnesium carbonate, carbon black, glass fiber, and carbon fiber strength. A composite material according to any one of