WO2010038784A1

WO2010038784A1 - Composite material containing carbon fiber

Info

Publication number: WO2010038784A1
Application number: PCT/JP2009/067045
Authority: WO
Inventors: 佳義單; 淳鈴木; 洋佐藤; 昭二川島
Original assignee: 保土谷化学工業株式会社; アキレス株式会社
Priority date: 2008-09-30
Filing date: 2009-09-30
Publication date: 2010-04-08
Also published as: JP5634870B2; CN102227782A; TW201027565A; HK1160545A1; JPWO2010038784A1; CN102227782B

Abstract

A conductive resin composite material comprising a base resin and carbon fibers, characterized in that the carbon fibers have an average outer diameter of 20-300 nm, excluding 20 nm, are of at least two kinds of carbon fibers which differ in outer-diameter distribution, and are contained in an amount of 1-11.2 parts by mass per 100 parts by mass of the base resin. The composite material containing carbon fibers has satisfactory conductivity and satisfactory resin material properties including elongation at break, etc., and carbon fiber shedding rarely occurs.

Description

Composite material containing carbon fiber

The present invention relates to a conductive resin composite material containing a resin material and carbon fiber. More specifically, the present invention has excellent conductivity as compared to conventional resin materials and conductive resin composite materials containing carbon fibers, while exhibiting excellent physical properties during processing and molding. The present invention relates to a conductive resin composite material containing a resin material and carbon fiber, characterized in that the carbon fiber from the resin composite material has low detachability.

Conventionally, a conductive resin composite material composed of a resin and a conductive filler has been widely used in the semiconductor field, electrical equipment related field, automobile / aviation field. The main purpose of using such a conductive resin composite material is, for example, protection of semiconductor components from static electricity, prevention of malfunction of precision equipment by blocking electromagnetic waves, prevention of static electricity and heat generation due to friction, etc. Can be mentioned.

By the way, as a method of imparting electrical conductivity to the base resin, a method of adding a material that imparts ion conductivity to the resin, or, for example, metal fine particles, metal fibers, carbon fine particles, carbon fibers (acrylic fibers or PAN-based carbon fiber or PITCH-based carbon fiber made by carbonizing pitch (by-products such as petroleum, coal, coal tar, etc.) at a high temperature as a raw material, hereinafter referred to as “general-purpose carbon fiber”. There is a method of adding a conductive filler such as. Under such circumstances, it is becoming mainstream to impart conductivity using a carbon-based material in terms of performance, environmental problems, and the like.

However, when carbon particles having a particle size of several μm are used as the conductive filler in order to develop the required conductivity, 40 to 50 parts by mass with respect to 100 parts by mass of the resin, carbon such as ketjen black Even in black, it is necessary to add 8 to 15 parts by mass. A composite material using such carbon particles causes changes in physical properties such as an increase in viscosity, a decrease in fluidity, and an increase in hardness as compared with the original resin. As a result, mold transferability during molding processing is deteriorated, appearance defects such as gloss and impact resistance are reduced.
In addition, when the above-mentioned general-purpose carbon fiber is used as the conductive filler, conductivity of about 10 ² Ωcm can be obtained by adding, for example, about 30 parts by mass with respect to 100 parts by mass of the resin. However, too much added amount leads to poor fluidity.

In recent years, fine carbon fibers having a fiber diameter of about 0.7 to 130 nm, such as carbon nanotubes (hereinafter also referred to as “CNT”), have come to be used as such conductive fillers. , Manufactured by arc discharge method or vapor phase growth method, etc. Basically, a graphene sheet composed of a continuous 6-membered ring carbon structure has a single-layer or multi-layer tubular structure, and the fiber diameter is nanometer It is a conductive filler material whose level and length are on the order of microns and is characterized by a high aspect ratio.When this fine carbon fiber is used, several parts by mass with respect to 100 parts by mass of the resin due to its high conductivity. It has been reported that a resin composite material having a desired conductivity can be obtained by adding (Patent Documents 1 and 2).

However, even in a conductive resin composite material composed of a base resin and such fine carbon fibers, the physical properties of the resin composite material such as elongation at break can be obtained by adding fine carbon fibers to the resin to a level that gives good conductivity.・ Moldability is reduced. These points are problems in molding a target molded article using this resin composite material. In addition, the fine carbon fiber has a very small fiber diameter and the wettability of the surface of the carbon fiber by the melted resin tends to drop off from the molded resin composite material. The dropping of the fine carbon fibers as the conductive filler has been regarded as a problem in the semiconductor field, in particular, causing failure / damage of the semiconductor product. For this reason, the resin and the carbon fiber that have reached a sufficient level in terms of both good electrical conductivity, resin characteristics inherent to the base resin such as excellent moldability, and low carbon fiber shedding. There is a need for a conductive resin composite material comprising:

On the other hand, Patent Document 3 proposes a gas storage material containing two or more groups of carbon fibers having different fiber outer diameter distributions. Combining a group of carbon fibers with a small average outer diameter and a group of carbon fibers with a larger average outer diameter forms an optimal pore structure for obtaining gas adsorption sites and improves the amount of gas stored. It is.

However, the gas storage material disclosed in Patent Document 3 is not a mixture of carbon fiber and resin material, and does not provide a resin material with good conductivity.

Further, Patent Document 4 proposes a conductive material in which a first graphite fine fiber and a second graphite fiber having a smaller diameter are contained in a resin binder.

The conductive material disclosed in Patent Document 4 is kneaded with a phenolic resin binder and also requires a solvent. Further, the fine graphite fibers used are a mixture of those having an average diameter of 5 to 20 nm and those having an average diameter of 300 to 1000 nm.

Further, Patent Document 5 proposes a conductive composition in which carbon fibers having a large average diameter and those having a small average diameter are mixed.

However, the carbon fiber of Patent Document 5 has a mean diameter of 13 μm and a mean diameter of 7 μm, and is a general-purpose carbon fiber.

JP 2006-306960 A JP 2006-225648 A JP 2005-185951 A JP-A-8-2222025 JP-A-5-32819

An object of the present invention is to provide a new conductive resin composite material including a resin material and carbon fiber. In particular, an object of the present invention is to provide a conductive resin composite material that has good electrical conductivity while improving break elongation related to moldability and that reduces the loss of carbon fibers from the resin composite material. To do.

As a result of intensive studies to solve the above problems, the present inventors have found that the average fiber outer diameter of the carbon fibers blended in the resin material is more than 20 nm and not more than 300 nm, and the fiber outer diameter distribution is different. The conductive resin composite material containing at least two groups of carbon fibers exhibits good electrical conductivity, and the elongation at break during molding is improved. Also, the carbon fibers can be removed from the conductive resin composite material. It was found to be reduced. In addition, there are few examples of industrial production of carbon fibers having an average outer diameter of 20 nm to 300 nm, and the present invention has developed a technology for producing carbon fibers having an average outer diameter of 20 nm to 300 nm. It was conceived and completed by mixing two carbon fiber groups having different fiber outer diameter distributions within the range. That is, the present invention has the following configuration.

A conductive resin composite material including a base material resin and carbon fibers, the carbon fibers having an average fiber outer diameter of more than 20 nm and not more than 300 nm, including at least two groups of carbon fibers having different fiber outer diameter distributions; and A conductive resin composite material comprising 1 to 11.2 parts by mass of carbon fiber with respect to 100 parts by mass of the base resin.

In the present invention, when at least two carbon fiber groups having different fiber outer diameter distributions are divided into a carbon fiber group A having a thinner average fiber outer diameter and a carbon fiber group B having a larger average fiber outer diameter, When the carbon fiber group B is larger than the carbon fiber group A, and the average fiber outer diameter of the carbon fiber group A is a and the average fiber outer diameter of the carbon fiber group B is b, the a / b ratio is The conductive resin composite material is characterized by being 0.8 or less.

In the present invention, the average outer diameter a of the carbon fiber group A is more than 20 nm and not more than 100 nm, and the average fiber outer diameter b of the carbon fiber group B is more than 100 nm and not more than 300 nm. The conductive resin composite material is substantially mixed and homogenized.

The present invention also shows the conductive resin composite material characterized in that the mass abundance ratio of the carbon fiber group A is smaller than the mass abundance ratio of the carbon fiber group B.

The present invention further shows the conductive resin composite material, wherein the carbon fiber is a carbon fiber produced by a vapor phase growth method.

In the present invention, the carbon fibers form a three-dimensional network-like carbon fiber structure, and the carbon fiber structure has a network structure in which a plurality of granular portions are sterically bonded to each other by the carbon fibers. It is the said conductive resin composite material characterized by the above-mentioned.

The present invention further shows the conductive resin composite material, wherein the granular portion has an average equivalent circle outer diameter of 1.3 times or more of an average fiber outer diameter of the carbon fiber.

The present invention also shows a conductive resin composite material characterized in that the breaking elongation of the conductive resin composite material is 40% or more.

The present invention further provides the conductive resin composite material, wherein a molded product formed using the conductive resin composite material has a surface electrical resistance value of 10 ³ to 10 ¹² Ω / □.

The conductive resin composite material of the present invention has excellent conductivity, improved elongation at break, and characteristics in which the carbon fibers are not easily dropped off by blending the above-described carbon fibers with the resin. With such characteristics, the conductive resin composite material can cope with a wide range of molding conditions, and the molding is excellent in crack resistance, so that a conductive material applicable to a wide range of applications can be provided. Such applications include, for example, personal computers, notebook computers, game machines (home game machines, arcade game machines, pachinko machines, slot machines, etc.), display devices (LCD, organic EL, electronic paper, plasma display, projectors, etc.) The power transmission component (represented by the housing of the dielectric coil power transmission device) is exemplified. Examples of such applications include printers, copiers, scanners, and fax machines (including these multifunction machines). Furthermore, examples of such applications include precision devices such as VTR cameras, optical film cameras, digital still cameras, camera lens units, security devices, and mobile phones. In particular, the conductive resin composite material of the present invention is suitably used for a housing, a cover, and a frame of a digital image information processing apparatus such as a camera barrel or a digital camera.

In addition, the conductive resin composite material of the present invention is a medical device such as a massage machine or a high oxygen treatment device; a home electric appliance such as an image recorder (so-called DVD recorder), an audio device, and an electronic musical instrument; a pachinko machine or a slot machine. It is also suitable for parts such as game machines such as home robots equipped with precision sensors.

In addition, the conductive resin composite material of the present invention includes various vehicle parts, batteries, power generation devices, circuit boards, integrated circuit molds, optical disk boards, disk cartridges, optical cards, IC memory cards, connectors, cable couplers, and electronic parts. Transport containers (such as IC magazine cases, silicon wafer containers, glass substrate storage containers, magnetic head trays, and carrier tapes), antistatic or charge removal parts (such as charging rolls for electrophotographic photosensitive devices), and various mechanical parts (Including mechanical parts for micromachines such as gears, turntables, rotors, and screws).

It is drawing explaining the mechanism of breaking elongation improvement. It is the structure figure which showed typically the structure of the carbon fiber manufacturing apparatus in this embodiment. (Large diameter product: small diameter product = 1: 5 (mass ratio)) It is a SEM photograph of mixed powder. It is a graph which shows the result of the viscosity measurement which concerns on this invention.

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

The present invention is a resin molded body obtained by kneading at least two carbon fiber groups having different fiber outer diameter distributions with a resin material. It is desirable that the carbon fiber groups having different fiber outer diameter distributions are manufactured separately and then kneaded into a resin material. The carbon fiber may be mixed at the powder stage or may be added separately to the resin and mixed after kneading.

The carbon fiber used in the present invention is not particularly limited as long as it uses at least two carbon fiber groups having different fiber outer diameter distributions as described above. A carbon fiber group having a diameter of more than 20 nm and not more than 100 nm, and a carbon fiber group having a large average outer diameter, those having an average outer diameter of more than 100 nm and not more than 300 nm are combined to make a mixture obtained by substantially mixing and homogenizing the two. It is preferable. By mixing the two together, the carbon fiber group having a small average outer diameter or only the carbon fiber group having a large average outer diameter is used alone, while maintaining good conductivity, the elongation at break relating to formability is reduced. It is possible to improve and reduce the loss of carbon fibers from the resin composite.

The average fiber outer diameter used here is a total of the number of measurement points of the fiber outer diameter of at least three fields of view taken at random with a scanning electron microscope in which the carbon fiber to be measured is set at a magnification of 35,000 times. All the fiber outer diameters that can be measured in each field of view are measured so that the number exceeds 50 points, and the number is averaged. The carbon fiber used in the conductive resin composite material of the present invention can measure the fiber outer diameter of approximately 20 to 50 points per visual field in the method.

Generally, the conductivity, viscosity, and breakage of a resin molded body obtained by adding carbon fiber are affected by the outer diameter of the carbon fiber. The conductivity tends to improve because the number per unit addition increases as the outer diameter decreases. Also, the viscosity tends to increase as the outer diameter decreases. Depending on the application, if the viscosity is high, the original physical properties of the resin are difficult to be exhibited. Regarding the manufacturing cost of carbon fiber, the manufacturing cost per unit mass increases as the outer diameter decreases. Therefore, the present invention has been conceived to achieve both the properties of the carbon fiber with a small outer diameter and the excellent properties of the thick one by kneading carbon fibers having different outer diameters. It is a thing.

For example, when carbon fiber group B having a larger average outer diameter is mixed with carbon fiber group A having a certain average outer diameter, carbon fiber group B alone is in a composite state in which it is roughly dispersed in the matrix resin matrix. In the product, the space between the carbon fiber of the carbon fiber group B and the resin can be filled with the carbon fiber of the carbon fiber group A, thereby increasing the electrical contact and improving the conductivity. Further, by dispersing the carbon fibers of the carbon fiber group B in the carbon fibers of the carbon fiber group A in the gaps in which the carbon fibers of the carbon fiber group B are dispersed, the carbon fibers are entangled and mechanical strength such as elongation at break increases (FIG. 1). ).

The fracture mechanism of polymer materials is determined by processing conditions and basic structure. Alternatively, the degree of crystallinity, the uniformity of the structure, the orientation, the size and distribution of spherulites, the crystallinity such as the length and distribution of molecular chains, and the presence of physical defects such as scratches and notches in materials. For example, as shown in FIG. 1, when there is a cut on the surface, the crack propagates along the molecular chain interface of the amorphous resin structure. As shown in FIG. 1, when carbon fiber is added, the shear stress is received by the carbon fiber, which is a bridging effect, and the propagation speed of the crack is slowed, so that the elongation at break can be improved.

The thinner the fiber, the larger the contact surface between the fiber surface and the resin, and the shear stress is dispersed, making it difficult for the fiber from pulling out. However, the smaller the fiber diameter, the higher the cost and the harder it is to disperse. For this reason, the present invention is a method in which a thin carbon fiber is dispersed around a large carbon fiber, so that even when a small amount of a thin carbon fiber is used, excellent elongation is maintained while maintaining excellent conductivity. Has the effect of improving.

Also, the carbon fiber used in the present invention is desirably a three-dimensional network structure having an average fiber outer diameter of more than 20 nm and not more than 300 nm. The carbon fiber structure is a carbon fiber structure characterized in that a plurality of the carbon fibers extend to have a granular portion that bonds the carbon fibers to each other. Such a carbon fiber structure is not particularly limited, but can be produced by a chemical vapor deposition method. Note that when the average outer diameter exceeds 300 nm, the number per unit amount decreases, so it is desirable to use an average outer diameter of 300 nm or less.

Furthermore, in the conductive composite material according to the present invention, the blending ratio of at least two groups of carbon fibers having different fiber outer diameter distributions is as described above in comparison with the case of using a single group of carbon fibers. There is no particular limitation as long as the improvement in electrical conductivity, the improvement in elongation at break, and the effect of reducing fiber dropout are obtained, but for example, carbon fiber A with a thinner average fiber outer diameter and carbon fiber B with a larger thickness When the carbon fiber B is larger than the carbon fiber A by mass ratio and the average fiber outer diameter of the carbon fiber A is a and the average fiber outer diameter of the carbon fiber B is b It is desirable that the ratio can be roughly divided so that the a / b ratio is 0.8 or less, more preferably 0.07 to 0.8, and still more preferably about 0.2 to 0.8. This is because a particularly excellent effect can be expected with such a blending ratio.

The vapor phase carbon fiber structure having the network structure further includes a plurality of granular portions, and the plurality of carbon fibers extend independently from the respective granular portions of the plurality of granular portions, respectively, and are three-dimensional as a whole. 3 of the gas-phase carbon fiber is at least partially formed by an aspect in which at least a part of the plurality of gas-phase carbon fibers extending from one granular part is bonded to other granular parts. A vapor-phase carbon fiber structure characterized by having a dimensional network structure is desirable.

In the specification of the present application, “extending” the carbon fiber from the granular part simply means that a plurality of carbon fibers are simply connected to the granular part by other binders (including carbon materials). As described above, the carbon crystal structural bond, that is, the granular portion mainly means a state in which the graphene sheets having the same multilayer structure as the carbon fiber are shared. To do.
Further, in the present specification, “exhibiting a three-dimensional expansion as a whole” means that a plurality of carbon fibers extend from one granular part in directions independent of each other, This means a structure in which a plurality of fibers extend in a three-dimensional space from the base point.

As such a carbon fiber structure, it is preferable that the average length of the carbon fibers connecting the two granular portions is 3.0 to 20.0 μm.

The “distance between two granular parts” means the length of the carbon fiber that connects from one granular part where the carbon fiber is extended to the adjacent granular part. The distance between the adjacent granular parts is obtained by measuring the distance 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 μm, the length of the carbon fiber is not sufficient and cannot be sufficiently extended and spread. For example, it is good when dispersed and blended in the base resin. There is a possibility that a conductive path cannot be formed. On the other hand, if the average distance exceeds 100 μm, the carbon fiber structure becomes a relatively large carbon fiber structure, and the base resin is This is because, when dispersed and blended, the viscosity increases, and the dispersibility of the aggregate of carbon fibers with respect to the base resin may be lowered. A more preferable average distance between the granular parts is preferably about 2.0 to 50 μm, and more preferably about 3.0 to 20 μm.

Further, the carbon fiber used in the present invention preferably has a standard deviation of the fiber outer diameter (nm) distribution of 25 to 40, particularly preferably 30 to 40. A conductive resin composite material using carbon fibers having a standard deviation of 25 to 40 exhibits a breaking elongation of 30% or more, and carbon fibers having a standard deviation of 30 to 40 exhibits a break elongation of 50% or more. This is because, in the carbon fiber having the three-dimensional network structure as described above that is preferably used in the present invention, the carbon fiber having a thick fiber outer diameter in the variation of the fiber outer diameter defined by the standard deviation range and It is considered that the carbon fiber having a thin outer diameter has a complementary effect on the elongation at break of the conductive resin composite using the carbon fiber.

In addition, in this application, it is also possible to reinforce electroconductivity and a mechanical characteristic by adding other fillers, such as carbon black, other than two carbon fiber groups.

The carbon fiber having the above average fiber outer diameter and the standard deviation value of the fiber outer diameter can be obtained in one production reaction if it is a batch type in the carbon fiber production method, or if it is a continuous reaction. It may be a carbon fiber obtained as a single continuous period for obtaining an appropriate production amount, or a mixture of carbon fibers obtained in such a manner. When performing the mixing, the carbon fiber group A and the carbon fiber group B are substantially mixed and homogenized, and the mass ratio of the carbon fibers derived from the carbon fiber group B in the mixture is the carbon fiber group A. A carbon fiber mixture larger than the mass abundance ratio of the derived carbon fiber is also desirable in satisfying the standard deviation range of the distribution of the average fiber outer diameter and the fiber outer diameter.

The carbon fiber preferably used in the present invention has the three-dimensional network structure, and has at least partially a network structure of the carbon fiber, not a simple branched structure. The fiber structure has a plurality of granular parts, and a plurality of carbon fibers having a fiber diameter thinner than the average equivalent circular outer diameter of each granular part extend from the granular part, and the granular parts are formed of the carbon fibers. It is formed during the growth process. As described above, the granular part, which is a connecting part of a plurality of carbon fibers, has the same graphene sheet multilayer structure as that of the carbon fibers, and thus provides a strong bond between the carbon fibers. Accordingly, the average equivalent circular outer diameter of the granular part desirable for stronger bonding is 1.3 times or more, more preferably 1.5 to 5.0 times the average fiber outer diameter of the carbon fiber. A carbon fiber structure in which strong carbon fibers are formed into a three-dimensional network by such strong bonding is retained even when added to the resin by kneading or the like. The granular portion having a larger outer diameter than the carbon fiber exhibits a physical anchoring effect in the resin matrix of the conductive resin composite material, thereby reducing the falling of the carbon fiber from the conductive resin composite material. It is thought that there is.

As used herein, the “average equivalent circular outer diameter of the granular part” means the observed area of the granular part, which is the bonding point between the vapor-phase carbon fibers, and the diameter was determined as one perfect circle. Value. Specifically, the outer shape of the granular portion, which is a bonding point between the vapor-phase carbon fibers, is photographed with an electron microscope or the like, and in this photographed image, the contour of each granular portion is converted into an appropriate image analysis software such as WinRoof (trade name). , Manufactured by Mitani Shoji Co., Ltd.), the area within the contour was determined, and the equivalent circle diameter of each granular portion was calculated and averaged based on the area.

The three-dimensional network-like carbon fiber structure preferably has an area-based circle equivalent average diameter of 20 to 100 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. This circle-equivalent average diameter is a factor for determining the fiber length of the carbon fiber structure when blended in the resin matrix. In general, when the circle-equivalent average diameter is less than 20 μm, the fiber length is There is a possibility that good electrical conductivity may not be obtained in a resin composite material using the same, and on the other hand, if it exceeds 100 μm, for example, a large increase in viscosity occurs when blended into a resin matrix by kneading or the like. Mixing and dispersion may be difficult or moldability may be deteriorated.

Further, the three-dimensional network-like carbon fiber structure has a bulky structure in which carbon fibers are sparsely present from the above structure. Specifically, for example, the bulk density is 0.001 to 0.05 g. / Cm ³ , more preferably 0.001 to 0.02 g / cm ³ . If the bulk density exceeds 0.05 g / cm ³ , it is difficult to improve the physical properties of the resin by adding a small amount.

The three-dimensional network-like carbon fiber structure is preferably formed by bonding carbon fibers present in the three-dimensional network form to each other in a granular portion formed during the growth process. As described above, a plurality of granular portions are included in the three-dimensional space, and the carbon fibers existing in the three-dimensional space are bonded to each other in the granular portions formed in the growth process. Thus, the electrical characteristics of the structure itself are very excellent. For example, the powder resistance value measured at a constant compression density of 0.8 g / cm ³ is 0.025 Ω · cm or less, more desirably 0.005 to 0.020 Ω · cm is preferable. This is because when the powder resistance value exceeds 0.025 Ω · cm, it is difficult to produce a good conductive composite material when it is made into a composite material with a resin.

In addition, the three-dimensional network-like carbon fiber structure preferably has high strength and conductivity, and it is desirable that there are few defects in the graphene sheet constituting the carbon fiber. Specifically, for example, Raman spectroscopy analysis It is desirable that the I _D / _IG ratio measured by the method is 0.2 or less, more preferably 0.1 or less. Here, in the Raman spectroscopic analysis, only a peak (G band) around 1580 cm ⁻¹ appears in large single crystal graphite. A peak (D band) appears in the vicinity of 1360 cm ⁻¹ due to the fact that the crystal has a finite minute size and lattice defects. For this reason, when the intensity ratio (R = I ₁₃₆₀ / I ₁₅₈₀ = I _D / I _G ) of the D band and the G band is equal to or less than the predetermined value as described above, it is recognized that the amount of defects in the graphene sheet is small. Because.

The defect here refers to an arrangement of graphene sheets caused by unnecessary atoms entering as an impurity, lack of necessary carbon atoms, or misalignment in the arrangement of graphene sheets constituting an intermediate or the like Incomplete part (lattice defect).

Further, although not particularly limited, it is desirable that the three-dimensional network-like carbon fiber has a combustion start temperature in air of 700 ° C. or higher, more preferably 750 to 900 ° C. As described above, the three-dimensional network-like carbon fiber has few defects and the carbon fiber has a desired outer diameter, and thus has such a high thermal stability.

The aggregate of carbon fibers according to the present invention preferably has a specific surface area of 10 to 60 m ² / g. When the specific surface area is increased to 60 m ² / g or more, the outer diameter of the carbon fiber becomes thin and dispersion and the like become difficult. On the other hand, when the specific surface area is 10 m ² / g or less, the number of carbon fibers per unit amount is extremely small, so that a highly conductive composite material cannot be obtained with a small amount.

The carbon fiber structure having the above characteristics is not particularly limited, but can be prepared, for example, as follows.

Basically, an organic compound such as a 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), which is further subjected to high-temperature heat treatment.

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 according to the present invention, it is preferable to use at least two or more carbon compounds having different decomposition temperatures as the carbon source. The “at least two or more carbon compounds” described in the present specification does not necessarily mean that two or more kinds of raw material organic compounds are used, and one kind of raw material organic compound is used. However, in the process of synthesizing the fiber structure, for example, a reaction such as hydrogen dealkylation of toluene or xylene occurs, and in the subsequent thermal decomposition reaction system, there are two different decomposition temperatures. 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 and 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 Of alcohol; In addition, adjust the gas partial pressure so that two or more carbon compounds selected from carbon monoxide, ketones, ethers, etc. can exhibit different decomposition temperatures in the desired thermal decomposition reaction temperature range, and combine them The fiber structure (intermediate body) can be produced efficiently by adjusting the residence time in a predetermined temperature range and / or adjusting 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, and even more preferably 3 It is desirable to set it to 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 fiber structure (intermediate body) having a three-dimensional network structure in which both fine carbon fiber portions and granular portions are sufficiently developed.

Although not necessarily limited, as a factor for controlling the thickness of the fiber outer diameter,
1) Concentration of hydrocarbon compound in raw material 2) Concentration ratio of hydrocarbon compound and catalyst metal in raw material 3) Residence time in reaction furnace.
In order to increase the outer diameter of the carbon fiber, the concentration of the hydrocarbon compound in the raw material may be increased. Further, the concentration ratio of the hydrocarbon compound and the catalyst metal in the raw material may be slightly increased by the molar ratio of the hydrocarbon compound and the catalyst metal as the outer diameter is increased. In the chemical vapor deposition method (CVD method), it is desirable to increase the amount of the metal catalyst used for growing the carbon fiber using the catalyst metal as a nucleus.

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

Further, 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 a sulfur compound such as sulfur or thiophene or iron sulfide is used.

The synthesis of the intermediate is carried out by using a conventional CVD method such as hydrocarbons, evaporating a mixture of hydrocarbons and catalysts as raw materials having a predetermined mixing ratio, and using hydrogen gas or the like as a carrier gas in the reactor. It is introduced and pyrolyzed at a temperature of 800-1300 ° C. As a result, from a few centimeters, a plurality of carbon fiber structures (intermediates) having a sparse three-dimensional structure in which fibers having an outer diameter of 100 to 300 nm are bonded together by granular materials grown using the catalyst particles as nuclei. Synthesize an aggregate of several tens of centimeters.

The production apparatus including the reaction furnace is not particularly limited, and for example, a production apparatus having the structure shown in FIG. 2 can be exemplified. The manufacturing apparatus 1 shown in the figure is a device that evaporates a raw material, mixes the gasified raw material with a carrier gas, introduces the raw material mixed gas into the reaction furnace 8, and manufactures carbon fiber in the reaction furnace 8. It is. The manufacturing apparatus 1 includes a raw material tank 2 filled with raw materials, and a gas tank 4 filled with a carrier gas for carrying the raw materials and introducing them into the reaction furnace 8. The raw material tank 2 and the gas tank 4 are introduced with raw materials. Each is connected to an evaporator 6 via a pipe 3 and a gas introduction pipe 5. Further, the evaporator 6 is connected to a reaction furnace 8 through a raw material mixed gas introduction pipe 7. The reaction furnace 8 for producing carbon fibers is formed in a cylindrical shape, and the conveyed raw material mixed gas is introduced into the reaction furnace 8 at the upper end forming one end in the axial direction. An introduction nozzle 9 is provided. Further, a heater is provided as a heating means 11 on the outer periphery of the reaction furnace 8, and the inside of the reaction furnace 8 is heated from the outer periphery of the reaction furnace 8. And the carbon fiber recovery device 12 which stocks and collects the produced carbon fiber is connected to the lower end side which makes the other end of the axial direction of the reaction furnace 8. A gas discharge pipe 13 for discharging gas is connected to the carbon fiber collector 12.

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 a three-dimensional network-like carbon fiber structure preferable as the carbon fiber as described above, the balance between the pyrolysis rate and the growth rate is intentionally changed. By using at least two or more carbon compounds having different decomposition temperatures as a source, the carbon material is grown three-dimensionally around the granular material without growing the carbon material only in a one-dimensional direction. Of course, the growth of such three-dimensional carbon fibers does not depend only on the balance between the thermal decomposition rate and the growth rate, but the crystal face selectivity of the catalyst particles, the residence time in the reactor, and the furnace temperature. The balance between the pyrolysis 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, etc. When the growth rate is faster than the thermal decomposition rate, the carbon material grows in a fibrous form. On the other hand, when the thermal decomposition rate is faster than the growth rate, the carbon material grows in the circumferential direction of the catalyst particles. To do. Therefore, by intentionally changing the balance between the pyrolysis rate and the growth rate, the carbon material growth direction as described above is made to be a multi-direction under control without changing the growth direction to a constant direction, as in the present invention. A three-dimensional structure can be formed. In order to easily form the three-dimensional structure in which the fibers are bonded with each other in the intermediate body to be produced, the composition of the catalyst, the residence time in the reaction furnace, the reaction temperature, and the gas temperature are used. Etc. are desirable.

In addition, as a method for efficiently producing a fiber structure (intermediate body), a method other than the above-described approach using two or more carbon compounds having different decomposition temperatures at an optimum mixing ratio is supplied to the reaction furnace. An approach for generating a turbulent flow in the vicinity of the supply port of the source gas can be mentioned. The turbulent flow here is a flow that is turbulent and turbulent and flows in a spiral.

In the reaction furnace, immediately after the raw material gas is introduced into the reaction furnace from the supply port, metal catalyst fine particles are formed by the decomposition of the transition metal compound as the catalyst in the raw material mixed gas. It is brought about through such a stage. That is, first, the transition metal compound is decomposed to become metal atoms, and then cluster generation occurs by collision of a plurality of, for example, about 100 atoms. At the stage of the generated cluster, it does not act as a catalyst for the fiber structure (intermediate body), and the generated clusters are further aggregated by collision and grow into metal crystalline particles of about 3 nm to 10 nm. It will be used as metal catalyst fine particles for the production of a structure (intermediate).

In this catalyst formation process, if there is a vortex due to intense turbulence as described above, more intense collision is possible compared to collisions between metal atoms or clusters with only Brownian motion, and by increasing the number of collisions per unit time Metal catalyst fine particles can be obtained in a high yield in a short time, and metal catalyst fine particles having a uniform particle size can be obtained by equalizing the concentration, temperature, etc. by vortex. 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. In this way, the metal catalyst fine particles are rapidly generated, and the area of the surface of the metal catalyst that is the decomposition reaction site of the carbon compound is increased, so that the decomposition of the carbon compound is promoted and sufficient carbon material is supplied. Carbon fiber grows radially with each metal catalyst fine particle of the aggregate as a nucleus, and when the thermal decomposition rate of some of the carbon compounds is faster than the growth rate of the carbon material as described above, The substance grows also in the circumferential direction of the catalyst particles, forms a granular portion around the aggregate, and efficiently forms a fiber structure (intermediate body) having an intended three-dimensional structure. The metal catalyst fine particle aggregate may include a part of catalyst fine particles that are less active than other catalyst fine particles or have been deactivated during the reaction. A non-fibrous or very short fibrous carbon material layer that has grown on the surface of such a catalyst fine particle before agglomeration or has grown into an aggregate after such a fine particle has become an aggregate. It seems that the granular part of a precursor is formed by existing in the peripheral position of a body. Therefore, the granular portion is composed of end portions of a plurality of vapor phase carbon fibers and metal catalyst fine particles in which a carbon material is grown only in the circumferential direction, and the granular portion that bonds the vapor phase carbon fibers to each other, Rather than a simple sphere, a large number of spheres are assembled and accumulated, and in this state, the carbon material continues to grow. The end portions of the plurality of vapor-phase carbon fibers and adjacent ones of the plurality of spherical structures form and share a continuous graphene sheet-like layer, and as a result, the plurality of vapor-phase carbon fibers are the granular portions. A three-dimensional network-like vapor-phase carbon fiber structure that is firmly bonded is formed.

In the vicinity of the raw material gas supply port of the reactor, the temperature of the raw material gas introduced is preferably 350 to 450 ° C. The specific means for generating the turbulent flow in the raw material gas flow is not particularly limited. For example, the raw material gas is introduced into the reaction furnace through a swirling flow or the raw material gas supply port. It is possible to adopt means such as providing some kind of collision portion at a position where it can interfere with the flow of the raw material gas. The shape of the collision part is not limited in any way, as long as a sufficient turbulent flow is formed in the reactor by the vortex generated from the collision part. It is possible to adopt a form in which one or a plurality of plates, paddles, taper tubes, umbrellas, etc. are arranged alone or in combination.

In the manufacturing apparatus 1 illustrated in FIG. 2, a rectifying / buffer plate 10 is provided around the introduction nozzle 9 as an example. The rectifying / buffer plate is an obstacle that is disposed in the vicinity of the introduction nozzle 9 and acts as a starting point of a collision that hinders the flow of the raw material mixed gas. The distribution and the concentration distribution can be made uniform. The shape of the rectifying / buffer plate is not limited in any way, and any shape may be used as long as the vortex generated from the rectifying / buffer plate as a starting point is sequentially formed up to the lower end side of the reaction furnace 8.

The intermediate obtained by heating the mixed gas of catalyst and hydrocarbon at a temperature set in the range of 800 to 1300 ° C has an incomplete structure as if patch-like sheet pieces made of carbon atoms were bonded together. Have. This intermediate has a very large D band and many defects when analyzed by Raman spectroscopy. The produced intermediate contains unreacted raw material, non-fibrous carbide, tar content and catalytic metal.

Therefore, in order to remove these residues from such an intermediate and obtain the desired carbon fiber structure with few defects, heat treatment is performed at a high temperature of 2400 to 3000 ° C. by an appropriate method.

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 2400 to 3000 ° C. to prepare the desired structure. At the same time, the catalyst metal contained in the fiber is removed by evaporation. 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.

When the intermediate is annealed at a temperature in the range of 2400 to 3000 ° C., the patch-like sheet pieces made of carbon atoms are bonded to each other to form a plurality of graphene sheet-like layers, and a desired carbon fiber is obtained. .

On the other hand, the resin that can be used for producing the conductive resin composite material of the present invention is not particularly limited, and examples thereof include epoxy resins, phenol resins, polyurethane resins, melamine resins, urea resins, aniline resins, and furan resins. Curable resin such as alkyd resin, xylene resin, unsaturated polyester resin, diaryl phthalate resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polycarbonate, polyphenylene oxide, polyphenylene ether, nylon 6, nylon 66, nylon 12, polyacetal, polyethylene , Polypropylene, polybutadiene, polyacrylonitrile, polystyrene, polymethyl methacrylate, polyethylene oxide, polytetramethylene oxide, thermoplastic polyurethane, Noxy resin, polyamide, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / propylene / non-conjugated diene copolymer, ethylene / ethyl acrylate copolymer, ethylene / glycidyl methacrylate copolymer, Ethylene / vinyl acetate / glycidyl methacrylate copolymer, ethylene / propylene-g-maleic anhydride copolymer, polyester polyether elastomer, polytetrafluoroethylene, cellulose acetate, ethyl cellulose, polydimethylsiloxane, polymethyl methacrylate, polyvinyl Acetate, polyvinyl alcohol, polyvinyl chloride, polyvinyl pyrrolidine, sucrose octaacetate, polystyrene, acrylotolyl / butanediene / styrene resin, polyvinyl chloride, acrylic Ronitrile / styrene resin, methacrylic resin, vinyl chloride, polyamide, polyacetal, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, ultrahigh molecular weight polyethylene, polyphenylene sulfide, polyimide, polyetherimide, polyarylate, polysulfone, polyethersulfone, poly Examples thereof include thermoplastic resins such as ether ether ketone, liquid crystal polymer, polytetrafluoroethylene, and modified products thereof. These resins may be homopolymers or copolymers, and may be a mixture of two or more.

The above-described carbon fiber is added to and mixed with the resin to form the conductive resin composite material according to the present invention. The compounding amount of the carbon fiber in the conductive resin composite material is preferably 1 to 11.2 parts by mass, more preferably 3 to 7.7 parts by mass with respect to 100 parts by mass of the resin. In the conductive resin composite material obtained by adding and mixing the desired amount of carbon fiber, the surface electrical resistance value is 10 ³ to 10 ¹² Ω / □, good electrical conductivity, and elongation at break related to moldability. Properties such as improvement and reduction of carbon fiber shedding from the resin composite are obtained. The conductive resin composite material having a surface electrical resistance value of 10 ³ to 10 ¹² Ω / □ is suitable for use in, for example, an IC component package such as a carrier tape or a transport tray for a magnetic head. In order to protect precision semiconductor parts from damage due to static electricity, conductive resin is used for parts containers, flooring at manufacturing sites, etc., and the surface electrical resistance value of the conductive resin in this case is 10 ⁶ to 10 ^12. Ω / □ is preferred. When the resistance value of the container is too low, the stored static electricity rapidly moves to the container, a discharge phenomenon occurs, and the part is short-circuited. In contrast, when the surface electrical resistance value of the electronic component container is 10 ⁶ to 10 ¹² Ω / □, static electricity is gently removed from the charged electronic component to the container side without causing a short circuit.

In addition, the conductive resin composite material has a break elongation of 30% or more while maintaining excellent conductivity, and preferably has a break elongation of 40% or more. Shows excellent resistance to cracking.

Further, the point that the carbon fiber from the conductive resin composite material has a low drop-off property is specifically, for example, by immersing the composite material (50 × 90 × 3 mm) in 2000 ml of ultrapure water, after the application of sound waves 60 seconds, the composite number of particles or particle size 0.5μm to fall off from the surface of the material follows the surface area per 5000counts / cm ² of the composite material, it preferably becomes 2500counts / cm ² or less Indicated by.

In the production of the conductive resin composite material according to the present invention, the method for producing a conductive resin composite by adding and mixing carbon fibers to the resin is not particularly limited. However, since excellent kneading performance is required for the dispersion of carbon fibers, it is preferable to melt knead the resin and carbon fibers using a twin screw extruder. In addition, the conductive resin composite material of the present invention has an advantage that a large twin screw extruder having a large heat load can be used due to its characteristics.

As a typical example of the twin screw extruder, ZSK (trade name, manufactured by Werner & Pfleiderer) can be mentioned. Specific examples of similar types include TEX (trade name, manufactured by Nippon Steel Works, Ltd.), TEM (trade name, manufactured by Toshiba Machine Co., Ltd.), KTX (product name, manufactured by Kobe Steel, Ltd.), and the like. Can be mentioned. In addition, melt kneaders such as FCM (manufactured by Farrel, trade name), Ko-Kneader (manufactured by Buss, trade name), and DSM (trade name, manufactured by Krauss-Maffei) can also be given as specific examples. Among the above, the type represented by ZSK is more preferable. In such a ZSK type twin screw extruder, the screw is a fully meshed type, and the screw includes various screw segments having different lengths and pitches, and various kneading disks having different widths (and corresponding kneading segments). It consists of

In the twin screw extruder, a more preferable aspect is as follows. As the screw shape, one, two, and three screw screws can be used, and in particular, a two-thread screw having a wide range of application in both the ability to convey the molten resin and the shear kneading ability can be preferably used. The ratio (L / D) of the screw length (L) to the diameter (D) in the twin-screw extruder is preferably 20 to 50, more preferably 28 to 42. When L / D is large, uniform dispersion is easily achieved, while when it is too large, decomposition of the base resin is likely to occur due to thermal degradation. The screw must have at least one kneading zone composed of a kneading disk segment (or a kneading segment corresponding thereto) for improving kneadability, and preferably has 1 to 3 kneading zones.

As the extruder, one having a vent capable of degassing moisture in the raw material and volatile gas generated from the melt-kneaded resin can be preferably used. From the vent, a vacuum pump is preferably installed for efficiently discharging generated moisture and volatile gas to the outside of the extruder. In addition, water, an organic solvent, a supercritical fluid, or the like may be added in order to enhance the dispersibility of the carbon fiber or remove impurities in the resin composite material as much as possible. Further, it is possible to install a screen for removing foreign matters mixed in the extrusion raw material in the zone in front of the extruder die portion to remove the foreign matters from the resin composite material. Examples of such a screen include a wire mesh, a screen changer, a sintered metal plate (such as a disk filter), and the like.

The method for supplying the carbon fiber to the extruder is not particularly limited, but the following method is typically exemplified. (I) A method of supplying carbon fibers into an extruder independently of a resin. (Ii) A method in which carbon fiber and resin powder are premixed using a mixer such as a super mixer and then supplied to the extruder. (Iii) A method in which carbon fibers and a resin are previously melt-kneaded into master pellets and supplied as a carbon fiber source. When carbon fibers having different fiber outer diameter distributions are used, the carbon fibers may be mixed before the step (i), and the carbon fibers may be mixed during the steps (i) to (iii). You may mix.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Preparation of carbon fiber Using the manufacturing apparatus shown in FIG. 2, carbon fiber group intermediates of a large diameter product (Production Example-1) and a small diameter product (Production Example-2) were obtained under the conditions shown in Table 1 below. After that, it was baked at 900 ° C. in an argon gas to separate and purify hydrocarbons such as tar contained as impurities. Next, this intermediate was subjected to high-temperature heat treatment (annealing) at 2600 ° C. in argon gas, and further pulverized with an airflow pulverizer to obtain an aggregate of carbon fibers comprising a three-dimensional network structure of carbon fibers.
The average fiber outer diameter of the carbon fiber group of the obtained large diameter product (Production Example-1) was 117 nm, and the standard deviation of the fiber outer diameter (nm) distribution was 26. On the other hand, the average fiber outer diameter of the carbon fiber group of the small diameter product (Production Example-2) was 58 nm, and the standard deviation of the fiber outer diameter (nm) distribution was 13.

Preparation of conductive resin composite material The large-diameter product and the small-diameter carbon fiber obtained in Example 1 were stirred in a closed tank at a mass ratio of 5: 1 for 2 hours or more to be mixed and homogenized. 6.38 parts by mass of the resulting mixture (FIG. 3) having an average fiber diameter of 102 nm was added to a polycarbonate resin (Lexan 141R (trade name, manufactured by SABIC Innovative Plastics)) and mixed uniformly. The mixture was supplied to the first inlet at the end using a vented twin screw extruder TEX-30XSST (trade name, manufactured by Nippon Steel Works, Ltd.) with a screw diameter of 30 mm. Such an extruder has a kneading zone by a kneading disk between the first supply port and the second supply port, and a vent port opened immediately after that is provided. The length of the vent port was about 2D with respect to the screw diameter (D). A side feeder was installed after the vent port, and a kneading zone with a kneading disk and a subsequent vent port were further provided after the side feeder. The length of the vent port in this part is about 1.5D, and the degree of vacuum is about 3 kPa in that part using a vacuum pump. Extrusion was performed under the conditions of a cylinder temperature of 300 ° C. (raise almost uniformly from the barrel at the root of the screw to the die), a screw rotation speed of 180 rpm, and a discharge amount of 20 kg per hour. The extruded strand was cooled in a water bath, then cut with a pelletizer and pelletized. The obtained pellets were dried at 120 ° C. for 5 hours and at 100 ° C. for 24 hours in a hot air circulating dryer, and then using an injection molding machine (Toshiba Machine IS55FPB), the cylinder temperature was 300 ° C., the mold temperature was 80 ° C., Test specimens for evaluation were produced under the conditions of a speed of 20 mm / sec and a molding cycle of about 60 seconds.

[Comparative Example 1]
Preparation of Conductive Resin Composite Material 6.38 parts by mass of the large-diameter carbon fiber obtained in Example 1 was added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 2]
Preparation of Conductive Resin Composite Material 7.53 parts by mass of the large-diameter carbon fiber obtained in Example 1 was added to the above polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 3]
Preparation of Conductive Resin Composite Material 4.17 parts by mass of the small-diameter carbon fiber obtained in Example 1 was added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 4]
Preparation of conductive resin composite material 6.38 parts by mass of the small-diameter carbon fiber obtained in Example 1 was added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

Preparation of conductive resin composite material The small-diameter product and the large-diameter product carbon fiber obtained in Example 1 were stirred in a sealed tank at a mass ratio of 2: 3 for 2 hours or more, mixed and homogenized, and then 5.0 parts by mass were added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

Preparation of Conductive Resin Composite Material The fine and large diameter carbon fibers obtained in Example 1 were stirred at a mass ratio of 1: 2 in a closed tank for 2 hours or more, mixed and homogenized, and then 6.0 parts by mass were added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

Preparation of conductive resin composite material The small-diameter product and the large-diameter product carbon fiber obtained in Example 1 were stirred in a closed tank at a mass ratio of 3: 5 for 2 hours or more, mixed and homogenized, and then mixed with the above. 8.0 parts by mass were added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 5]
Preparation of Conductive Resin Composite Material 4.0 parts by mass of the small-diameter carbon fiber obtained in Example 1 was added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 6]
Preparation of Conductive Resin Composite Material 5.0 parts by mass of the small-diameter carbon fiber obtained in Example 1 was added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 7]
Preparation of Conductive Resin Composite Material 6.0 parts by mass of the large-diameter carbon fiber obtained in Example 1 was added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 8]
Preparation of Conductive Resin Composite Material 7.0 parts by mass of the large-diameter carbon fiber obtained in Example 1 was added to the polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

[Comparative Example 9]
Preparation of Conductive Resin Composite Material 8.0 parts by mass of the large-diameter carbon fiber obtained in Example 1 was added to the above polycarbonate resin, and a test piece for evaluation was produced in the same manner as in Example 2.

The physical properties of the conductive resin composite material were measured according to the following method.

(1) Surface electrical resistance Referring to JIS K 7194 (Resistance testing method for conductive plastics using 4-probe method), according to the measurement position and measurement method, Loresta GP (MCP-T600 type, Mitsubishi Chemical Corporation) The surface resistance of the injection-molded test piece (50 × 90 × 3 mm) was measured by using Hiresta UP (MCP-HT450 type, manufactured by Mitsubishi Chemical Corporation, product name). The obtained results are shown in Table 2 and Table 3.

(2) Volume electric resistance A 20 mm × 20 mm × 2.5 mm thick sample piece was cut out from the injection-molded test piece, and silver paste (Sylbest P, manufactured by Tokushi Chemical Co., Ltd.) was formed on two parallel sides of 20 mm × 2.5 mm. -248) was applied and the ends of copper wire electrodes of about 10 cm were adhered. This copper wire electrode was connected to an input / output terminal of a DC voltage / current source / monitor R6243 (manufactured by ADC Corporation) with an alligator clip and a dedicated cable. Using this apparatus, the volume resistance Rv (unit: Ωcm) of the sample was measured by the two-terminal method. A voltage V (unit: V) was applied, and the read current value (I: unit: A) was recorded. The volume resistance Rv of the sample is the measured value R = (V of the resistance of the sample from the cross-sectional area S in the current direction = sample width W × thickness t (unit: cm ² ) and sample length L (unit: cm)). / I), volume resistivity Rv = (V / I) × W × t / L (Ωcm) can be calculated. In the above sample, W = 2 cm, L = 2 cm, and t = 0.25 cm. The obtained volume electric resistance results are shown in Table 3.

(3) Elongation at break The tensile elongation at break was measured in accordance with ISO 527-1 (general rules) and 527-2 (test conditions for mold molding, extrusion molding and cast plastic). The shape and size of the injection-molded test piece is a test piece 1A type of ISO527-2. The testing apparatus was a universal material testing machine (Intesco 2005-5 type), the test speed was 50 mm / min, the distance between chucks was 115 mm, and the test was performed in a test environment of 23 ° C. and 50% RH. The average value of the breaking elongation values of the five test pieces molded and measured in the same manner as described above was calculated. The obtained results are shown in Table 2.

(4) Separability 2000 mL of ultrapure water was injected into a 3000 mL glass beaker washed with ultrapure water, and one injection-molded test piece (50 × 90 × 3 mm) was immersed therein. Thereafter, ultrasonic waves were applied for 1 minute using 5210E-DTH (47 kHz / 140 W) (trade name, manufactured by BRANSON). Thereafter, the extracted ultrapure water was sucked with an in-liquid particle measuring instrument HIAC ROYCO SYSTEM8011 (trade name, manufactured by HACH ULTRA ANALYTICS), and the amount of dust generated with a dust particle diameter of 0.5 μm or more was measured. The obtained results are shown in Table 2.

As shown in the results in Tables 2 and 3 above, a comparison is made between a mixture of two types of carbon fibers having different fiber diameter distributions and a mixture using only a large diameter product. When Example 1, Example 4 and Comparative Example 7 were compared, and Example 5 and Comparative Example 9 were compared, it was confirmed that the mixed product showed better conductivity than the large-diameter product even with the same mass part of carbon fiber. On the other hand, in Example 2 and Comparative Example 4, and in Example 3 and Comparative Example 6, the smaller diameter product showed better conductivity at the same mass part. This is because thin products tend to be superior in terms of improving conductivity. However, as described above, the manufacturing cost of the small-diameter product is high, and when kneaded into the resin, the viscosity is increased and the original physical properties of the resin are difficult to be obtained. Therefore, in Table 2, the elongation at break is good for the mixed product. The mixed product exhibits a sufficient surface electric resistance value and volume electric resistance value, and the elongation at break exceeds 60%. Therefore, it can be said that the mixed product is excellent in exhibiting balanced properties in imparting mechanical properties and conductivity to the resin.

[Example 6 and Comparative Examples 10 and 11]
Large-diameter carbon fiber structure obtained in Example 1 (Comparative Example 10), small-diameter carbon fiber structure (Comparative Example 11), or gas phase carbon of these large-diameter products and small-diameter products 0.22 g of each carbon fiber structure was respectively adjusted so that the content of the mixed product (Example 6) obtained by mixing and homogenizing the fiber structure at a mass ratio of 5: 1 was 2.0% by mass. An epoxy resin (Adeka Resin EP4100E, epoxy equivalent 190, manufactured by ADEKA Corporation) 10 g, a curing agent (Adeka Hardener EH3636-AS, manufactured by ADEKA Co., Ltd.), and a rotation-revolution centrifugal stirrer (Atsutori Rentaro, AR-250, manufactured by Shinky Co., Ltd.) was kneaded for 10 minutes, and an epoxy resin kneaded material of a carbon fiber structure for viscosity measurement was prepared.

Carbon fibers of Comparative Example 10, Comparative Example 11 and Example 6 in a high-performance rotary rheometer (Gemini 150, manufactured by Bhlin Instruments) at a temperature of 25 ° C., a frequency range of 0.01 to 10 Hz, and an Auto-stress mode. The viscosity (Complex Viscosity) of a 2.0 mass% mixture of the structure and the epoxy resin was measured. The result is shown in FIG.
As can be seen from FIG. 4, the viscosity of the epoxy resin mixture of the mixed product (Example 6) is equivalent to the viscosity of the epoxy resin mixture of the large diameter product (Comparative Example 10), and the epoxy resin mixture of the small diameter product (Comparative Example). It can be seen that the viscosity is considerably lower than the viscosity of 11).

Therefore, the conductive resin composite material of the present invention is extremely useful for various industrial uses such as the field of OA equipment and the field of electrical and electronic equipment, and the industrial effect exerted thereby is extremely great.

DESCRIPTION OF SYMBOLS 1 ... Carbon fiber manufacturing apparatus 2 ... Raw material tank 3 ... Raw material introduction pipe 4 ... Gas tank 5 ... Gas introduction pipe 6 ... Evaporator 7 ... Raw material mixed gas introduction pipe 8 ... Reactor 9 ... Introduction nozzle 10 ... ... Rectification / buffer plate 11 ... Heating means 12 ... Carbon fiber recovery device 13 ··· Gas discharge pipe 14 ··· Raw material mixed gas inlet 15 ··· Cooling gas inlet 16 ··· Cooling gas outlet 20 ··· Metal catalyst particle generation zone 30 .... Carbon fiber production zone

Claims

A conductive resin composite material including a base material resin and carbon fibers, the carbon fibers having an average fiber outer diameter of more than 20 nm and not more than 300 nm, including at least two groups of carbon fibers having different fiber outer diameter distributions; and A conductive resin composite material comprising 1 to 11.2 parts by mass of carbon fiber with respect to 100 parts by mass of the base resin.
When at least two carbon fiber groups having different fiber outer diameter distributions are divided into a carbon fiber group A having a smaller average fiber outer diameter and a carbon fiber group B having a larger average fiber outer diameter, the carbon fiber group B has a mass ratio. When the average fiber outer diameter of the carbon fiber group A is a and the average fiber outer diameter of the carbon fiber group B is b, the a / b ratio is 0.8 or less. The conductive resin composite material according to claim 1, wherein
The average outer diameter a of the carbon fiber group A is more than 20 nm and not more than 100 nm, and the average fiber outer diameter b of the carbon fiber group B is more than 100 nm and not more than 300 nm, and both are substantially mixed in the matrix resin. The conductive resin composite material according to claim 1, wherein the conductive resin composite material is homogenized.
The conductive resin composite material according to any one of claims 1 to 3, wherein the carbon fiber is a carbon fiber produced by a vapor phase growth method.
The carbon fiber forms a three-dimensional network-like carbon fiber structure, and the carbon fiber structure has a network structure in which a plurality of granular parts are sterically bonded to each other by the carbon fiber. Item 5. The conductive resin composite material according to any one of Items 1 to 4.
The conductive resin composite according to any one of claims 1 to 5, wherein the granular part has an average equivalent circular outer diameter of 1.3 times or more of an average fiber outer diameter of the carbon fiber. material.
The conductive resin composite material according to any one of claims 1 to 6, wherein the elongation at break of the conductive resin composite material is 40% or more.
The conductive property according to any one of claims 1 to 7, wherein a surface electrical resistance value of a molded product molded using the conductive resin composite material is 10 3 to 10 12 Ω / □. Resin composite material.