JP2007231471A - Method for producing fine carbon fiber aggregate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a fine carbon fiber aggregate, by which the fibrous aggregates of the fine carbon fiber aggregate, having excellent electrical characteristics, thermal characteristics and mechanical characteristics, and having an average diameter of <150 μm corresponding to a circle based on its area in economically advantageously and in a good efficiency. <P>SOLUTION: This method for producing the fine carbon fiber aggregate having an average mean diameter of <150 μm corresponding to the circle based on the area includes air stream-crushing and/or air stream-disintegrating the fine carbon fiber aggregate having ≥150 μm mean diameter corresponding to the circle based on the area before heat-treating the fine carbon aggregate at 1,800 to 3,000°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a method for producing a fine carbon fiber aggregate useful as an additive suitable for improving physical properties such as electrical properties and thermal properties of a coating material, and the fine carbon fiber aggregate obtained by this production method. It relates to a coating material.

  As a method for producing fine carbon fibers, a vapor phase growth method is known in which hydrocarbons serving as a carbon source such as benzene, toluene or xylene are thermally decomposed in a gas phase. For example, there are a substrate method in which metal fine particles are dispersed on a substrate placed in a thermal decomposition zone and fine carbon fibers are grown therefrom, and a floating method in which fine carbon fibers are generated using floating metal fine particles as a catalyst. The fine carbon fiber obtained by this vapor phase growth method is expected as an additive for improving the performance of a base material such as an organic material, an inorganic material, and a metal material and exhibiting a new function.

  However, the fine carbon fiber obtained by this vapor growth method has a very large aspect ratio, and van der Waals force acts between the fine carbon fibers. For this reason, the manufactured fine carbon fiber is produced | generated in the aggregation state intertwined closely (patent document 1 and patent document 2).

For example, in the fine carbon fiber obtained by the substrate method, the fine carbon fibers are entangled with each other to form a granular aggregated state. In addition, entanglement occurs with respect to the fine carbon fiber obtained by the floating method. When agglomerated fine carbon fibers are used, the dispersion of carbon fiber aggregates does not proceed in a matrix such as a resin, and conventionally, a method of subdividing fine carbon fibers having formed an agglomerated state has been performed.
As a conventional subdivision method, for example, Patent Document 1 discloses a method of pulverizing using a vibrating ball mill, and Patent Document 2 discloses that a vapor-grown carbon fiber is graphitized at 2400 ° C. or higher and then converted into a jet mill. , A method of mechanically pulverizing with a ball mill, a rotor speed mill, a cutting mill, a homogenizer, a vibration mill, or an attritor as shown in Patent Document 3, and Patent Document 4 includes a high impact force processing apparatus equipped with impact blades. A method of cutting and dispersing the generated fine carbon fiber by applying a high impact force to the generated fine carbon fiber by using it may be mentioned.

  However, there are various problems in the conventional method of pulverizing and subdividing the agglomerated fine carbon fibers. For example, in a ball mill type pulverizer classified as crushing, since the fine carbon fibers are crushed and broken by the rigid balls used as the pulverizing media, the fine carbon fibers themselves cause structural defects. The physical properties such as conductivity will be lowered. In addition, when a grinding medium such as a ceramic sphere is used, ceramic powder is generated, and this ceramic powder is mixed into the fine carbon fibers that are subdivided as impurities.

In addition, since the fine carbon fiber that has been subjected to high-temperature heat treatment (annealing) is an elastic body, when attempting to air-pulverize this, (i) the air layer present on the surface of the fine carbon fiber is It is necessary to use severe conditions in the crushing, such as the problem that it exists in the middle in the collision between fine carbon fibers or the collision with the wall or moving body to suppress the impact and cause the reduction of crushing efficiency. There was a problem of requiring a lot of energy.
Japanese Patent Laid-Open No. 3-74465 Japanese Unexamined Patent Publication No. 63-21208 JP-A-64-65144 JP-A-4-222227

  An object of the present invention is to provide fine carbon fiber aggregates having excellent electrical properties, thermal properties, and mechanical properties and having an area-based circle equivalent average diameter of less than 150 μm, which is economically advantageous and efficient. It is providing the manufacturing method of a fiber assembly. Moreover, the objective of this invention is providing the coating material containing the fine carbon fiber aggregate | assembly obtained in that way.

  In the present invention, fine carbon fiber aggregates (hereinafter referred to as fine carbon fiber aggregates used for pulverization and / or defibration) having an area-based circle equivalent average diameter of 150 μm or more are subjected to airflow pulverization and / or airflow defibration. Thereafter, heat treatment is performed at 1800 to 3000 ° C., and a fine carbon fiber aggregate having an area-based circle-equivalent mean diameter of less than 150 μm (hereinafter, a fine carbon fiber aggregate obtained by annealing after pulverization and / or defibration) Is provided).

  Furthermore, this invention provides the coating material containing the fine carbon fiber aggregate obtained by this manufacturing method, and an organic binder.

  In the present invention, “fine carbon fiber” refers to a fiber having a fibrous portion composed of carbon having an outer diameter of 500 nm or less, more preferably an outer diameter of about 15 to 100 nm. Further, “pulverization” refers to cutting the fiber to shorten the fiber length, and “defibration” refers to loosening the state in which the fibers are intertwined without being substantially cut.

  According to the present invention, the fine carbon fiber aggregate was pulverized and / or defibrated efficiently and economically without significantly reducing the characteristic physical properties such as conductivity and without using a great amount of pulverization energy. A fine carbon fiber aggregate can be obtained. Moreover, if the fine carbon fiber aggregate obtained by this production method is used as a component of the conductive coating material, a conductive film having a good appearance without an aggregate resulting from the fine carbon fiber aggregate in the coating film is obtained. be able to.

Hereinafter, the present invention will be described in detail based on embodiments.
[A fine carbon fiber aggregate used for pulverization and / or defibration]
In the present invention, the fine carbon fiber aggregate subjected to pulverization and / or defibration may be a so-called as grown after fine carbon fiber synthesis such as vapor phase growth method, but after that, Although what received the history may be used, Preferably, the thing which has not received high temperature heat processing (annealing process), specifically, the thing which has not received the heat history of 1800-3000 degreeC is used. By using such a fine carbon fiber aggregate, the fine carbon fiber aggregate is efficiently pulverized and / or defibrated while suppressing damage to the fine carbon fiber aggregate without using much pulverization energy and / or defibration energy. be able to.

  In particular, after the synthesis of the fine carbon fiber, it is preferable to heat at 800 to 1200 ° C. to remove unreacted raw materials and / or tars and not to receive a heat history at 1800 to 3000 ° C.

  As a fine carbon fiber aggregate used for pulverization and / or defibration, any carbon fiber aggregate having a carbon fiber portion with an outer diameter of 500 nm or less can be used in the production method of the present invention. Among these, when the fine carbon fiber aggregate obtained by annealing after pulverization and / or defibration obtained in the production method of the present invention is added to a matrix such as a resin, it is sufficient even if the addition amount is small. In order to exhibit electrical characteristics, mechanical characteristics, thermal characteristics, etc., the fine carbon fiber aggregate has as fine a carbon fiber as possible, and these carbon fibers are not separated from one another. It is preferably an aggregate of carbon fiber structures having a structure that is firmly bonded and held in a resin with a sparse structure.

  That is, as a fine carbon fiber aggregate used for pulverization and / or defibration in the present invention, an aggregate of carbon fiber structures having a three-dimensional network structure composed of carbon fibers having an outer diameter of 15 to 100 nm. The three-dimensional network-like carbon fiber structure has a granular part that couples the carbon fibers to each other in a form in which a plurality of the carbon fibers extend, and the granular part is a growth of the carbon fiber. It is preferably formed in the process.

  Such a carbon fiber structure is, for example, a three-dimensional network-like carbon composed of a carbon fiber structure having an outer diameter of 15 to 100 nm as seen in FIG. 1 (SEM photograph) and FIG. 2 (TEM photograph). It is a fiber structure, Comprising: The said carbon fiber structure has a granular part which couple | bonds the said carbon fiber mutually in the aspect with which the said carbon fiber is extended in multiple numbers.

  In the fine carbon fiber aggregate used for pulverization and / or defibration, the outer diameter of the carbon fiber constituting the carbon fiber structure is preferably in the range of 15 to 100 nm. In this case, when the fine carbon fiber aggregate obtained by pulverization and / or defibration and obtained by annealing in the production method of the present invention is used as a modifier or additive in a matrix such as a resin, it is high. This is because conductivity is obtained. In a fine carbon fiber aggregate obtained by annealing after pulverization and / or defibration, a cylindrical graphene sheet having this outer diameter range is laminated in a direction perpendicular to the axis, that is, a multilayer is difficult to bend. In addition, since elasticity, that is, the property of returning to the original shape after deformation, is imparted, the carbon fiber structure has a sparse structure even after being compressed and after being placed in a matrix such as a resin. It becomes easy.

  Furthermore, as shown in FIG. 2, the particle size of the granular part is larger than the outer diameter of the fine carbon fiber, preferably 1.3 to 250 times, more preferably 1.5 to 100 times, and still more preferably. It is desirable that it is about 2.0 to 25 times. In addition, the said value is an average value. When the particle size of the granular part, which is the bonding point between the carbon fibers, is sufficiently large as described above, a high bonding force is brought about for the carbon fiber extending from the granular part, and pulverization and / or disintegration is achieved. Even in the fiber process, the carbon fiber structure itself is not easily destroyed, and when a fine carbon fiber aggregate obtained by annealing after pulverization and / or defibration is placed in a matrix such as a resin, a certain degree of elasticity Can be dispersed in the matrix while maintaining the three-dimensional network structure. 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.

Further, in the carbon fiber structure used as a fine carbon fiber aggregate to be subjected to pulverization and / or defibration, carbon fibers existing in a three-dimensional network are bonded to each other in the granular part, and the carbon The fiber has a shape in which a plurality of fibers extend, and thus the structure has a bulky structure in which carbon fibers are sparsely present. Specifically, for example, a fine structure that is used for pulverization and / or defibration. The bulk density of the carbon fiber aggregate is desirably 0.0001 to 0.05 g / cm ³ .

[Manufacturing process of fine carbon fiber aggregate used for pulverization and / or defibration]
Basically, an organic compound such as hydrocarbon is chemically pyrolyzed by CVD using transition metal ultrafine particles as a catalyst to obtain an aggregate of fine carbon fibers (hereinafter referred to as an intermediate) used in the present invention.

  As the raw material organic compound, hydrocarbons such as benzene, toluene and xylene, alcohols such as carbon monoxide (CO) and ethanol can be used. In obtaining an aggregate of fine carbon fiber structures used as preferred in the present invention, it is preferable to use at least two or more carbon compounds having different decomposition temperatures as a 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 aggregate of fine carbon fiber structures, for example, a reaction such as hydrodealkylation of toluene or xylene occurs, and in the subsequent thermal decomposition reaction system, decomposition occurs. An embodiment in which two or more carbon compounds having different temperatures are included is also included. As the atmospheric gas, an inert gas such as argon, helium, xenon, or hydrogen can be used.

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

  Preparation of a fine carbon fiber structure aggregate to be subjected to pulverization and / or defibration as preferred in the present invention is performed by using a commonly used CVD method such as hydrocarbon, and the raw material hydrocarbon and catalyst. The mixed liquid is evaporated, hydrogen gas or the like is introduced into the reaction furnace as a carrier gas, and is thermally decomposed at a temperature of 800 to 1300 ° C. As a result, several tens of centimeters to several tens of centimeters of carbon fiber structures having a sparse three-dimensional structure in which carbon fibers having an outer diameter of 15 to 100 nm are bonded together by granular materials grown using the catalyst particles as nuclei. Synthesize an aggregate of size.

  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 the form of fine carbon. However, in obtaining the aggregate of carbon fiber structures used in this step, the balance 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 carbon compounds having different from each other, the carbon material is grown three-dimensionally around the granular body without growing the carbon material only in 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 surface 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 deliberately changing the balance between the pyrolysis rate and the growth rate, the aforementioned three-dimensional structure can be controlled in multiple directions under control without making the growth direction of the carbon material as described above constant. It can be formed. In the assembly of fine carbon fiber structures used for pulverization and / or defibration, in order to easily form the above-described three-dimensional structure in which the fibers are bound together by granular materials, the composition of the catalyst and the like It is desirable to optimize the residence time in the reaction furnace, the reaction temperature, the gas temperature, and the like.

  An assembly of fine carbon fiber structures used for pulverization and / or defibration obtained by heating a mixed gas of catalyst and hydrocarbon at a constant temperature in the range of 800 to 1300 ° C is a patch comprising carbon atoms. When a Raman spectroscopic analysis is performed, the D band is very large and has many defects as will be described later. Moreover, the aggregate | assembly of the fine carbon fiber structure used for grinding | pulverization and / or defibration obtained in this way contains an unreacted raw material, a non-fibrous carbide, a tar content, and a catalyst metal.

In the present invention, an aggregate of fine carbon fiber structures subjected to pulverization and / or defibration is heated to 800 to 1200 ° C. in an inert gas atmosphere such as N ₂ , Ar, etc. It is preferable to remove volatile components such as.

In addition, the aggregate of fine carbon fiber structures subjected to pulverization and / or defibration, for example, has an I _D / _IG ratio measured by Raman spectroscopy of preferably more than 0.2. It is desirable to be 5 or less. Here, in the Raman spectroscopic analysis, only a peak (G band) near 1580 cm ⁻¹ appears in large single crystal graphite. A peak (D band) appears in the vicinity of 1360 cm ⁻¹ due to the crystal having a finite minute size or lattice defects. For this reason, when the intensity ratio of the D band and the G band (R = I ₁₃₆₀ / I ₁₅₈₀ = I _D / I _G ) is within the predetermined value range as described above, it is used for pulverization and / or defibration. The amount of defects in the aggregate of fine carbon fiber structures is within a predetermined range.

[Airflow crushing and / or airflow defibrating process]
The fine carbon fiber aggregate thus obtained, preferably an aggregate of fine carbon fiber structures, is subjected to airflow pulverization and / or airflow defibration. As a method of airflow pulverization and / or airflow defibration, a method of applying pressure fluctuation to a fine carbon fiber aggregate, preferably an aggregate of fine carbon fiber structures (hereinafter sometimes referred to as a fine carbon fiber aggregate). Is mentioned. As a method for doing this, for example, New Microcyclomat (trade name, manufactured by Masuno Seisakusho Co., Ltd.) and the like can be mentioned.

  Whether to use airflow pulverization or airflow defibration is appropriately determined according to the original bulk density, average diameter, etc. of the fine carbon fiber aggregate to be treated. For example, the pressure for giving the pressure fluctuation It can be done by adjusting.

By this airflow pulverization and / or airflow defibration, the fine carbon fiber aggregate is pulverized and / or defibrated to an area-based circle equivalent average diameter of less than 150 μm, preferably less than 140 μm, more preferably less than 130 μm. In this case, the bulk density of the fine carbon fiber aggregate after pulverization and / or defibration in this step is 0.02 g / cm ³ or less, preferably 0.01 g / cm ³ or less, more preferably 0.005 g / cm. It is preferable to set it to ³ or less, since it can be pulverized and / or defibrated without leaving an aggregate when further pulverized and / or defibrated after annealing. The pulverization and / or defibration process may be performed in multiple stages from the viewpoint of pulverization efficiency and / or defibration efficiency in order to satisfy the above-mentioned equivalent circle average diameter.

[Heat treatment (annealing) at 1800 to 3000 ° C.]
The fine carbon fiber aggregate subjected to airflow pulverization and / or airflow defibration as described above is heat-treated (annealed) at 1800 to 3000 ° C. By performing this heat treatment step, a desired structure to be described later is prepared, and at the same time, the catalyst metal contained in the fine carbon fiber aggregate is evaporated and removed. 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 fine carbon fiber structure.

  In this heat treatment step, the patch-like sheet pieces made of carbon atoms are bonded to each other to form a plurality of graphene sheet-like layers. Therefore, the fine carbon fiber aggregate obtained in this step is dispersed and blended in the matrix. In this case, a good conductive path can be formed.

[A fine carbon fiber aggregate obtained by annealing after pulverization and / or defibration]
In the fine carbon fiber aggregate obtained in this way, the carbon fiber structure has fine carbon fibers having such a predetermined outer diameter in a three-dimensional network form. These carbon fibers are grown on the carbon fibers. In the granular part formed in the process, they are bonded to each other and have a shape in which a plurality of the carbon fibers extend from the granular part. In this way, the fine carbon fibers are not simply entangled with each other, but are firmly bonded to each other in the granular portion, so that when the structure is disposed in a matrix such as a resin, the structure is Without being disperse | distributed as a carbon fiber single-piece | unit, it can be disperse-blended in a matrix with a bulky structure. Further, in such a carbon fiber structure, since the carbon fibers are bonded to each other by the granular part formed in the growth process of the carbon fiber, the electrical characteristics of the structure itself are very excellent. For example, the electrical resistance value measured at a constant compression density is obtained by attaching a simple entangled body of fine carbon fibers or a joining point between fine carbon fibers by a carbonaceous material or a carbide thereof after the synthesis of the carbon fiber. Compared with the value of the structure or the like, it shows a very low value, and when it is dispersed and blended in the matrix, a good conductive path can be formed.

Also, I _{D /} I _G ratio of grinding and / or defibrilated foreign, annealed to the obtained fine carbon fiber aggregate, 0.2 or less from the above having a high mechanical strength and conductivity, and more preferably 0. 1 or less is desirable.

In the thus obtained fine carbon fiber aggregate, true density narrowed spacing of graphene sheets stacked is increased 1.89g / cm ³ 2.1g / cm ³ from (pre-anneal) (after annealing) In addition, the carbon fiber has a polygonal axial cross section, and the carbon fiber having this structure is dense and has few defects in both the laminating direction and the surface direction of the cylindrical graphene sheet constituting the carbon fiber. The rigidity (EI) is improved.

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

In addition, the carbon fiber structure in the fine carbon fiber aggregate obtained in this way is because the carbon fibers present in a three-dimensional network form are bonded to each other in the granular part formed in the growth process. As described above, 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 preferably 0.02 Ω · cm or less. Is preferably 0.001 to 0.010 Ω · cm. A powder resistance value of 0.02 Ω · cm or less is preferable because a good conductive path can be formed when blended in a matrix such as a resin.

  In the present invention, each physical property value is measured as follows.

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

<Area-based circle equivalent average diameter>
First, a photograph of an aggregate of carbon fiber structures is observed with an optical microscope and photographed. In the obtained photograph, only the carbon fiber structure aggregate with a clear outline is the object to be measured, the carbon fiber structure is broken, or the area-based circle equivalent diameter is 5 microns or less Or the object whose outline is unclear was not considered. All aggregates of carbon fiber structures that can be targeted in one field of view were used, and aggregates of 200 or more carbon fiber structures in three fields of view were targeted. The outline of each carbon fiber structure aggregate targeted is traced using image analysis software WinRoof (trade name, manufactured by Mitani Corp.) to determine the area within the outline, The equivalent circle diameter was calculated and averaged.

<Surface resistance value>
A low resistivity meter Loresta-GP (MCP-T600) manufactured by Mitsubishi Chemical Corporation was used and measured according to JIS K 7194 using an ECP probe.

<Raman spectroscopy>
Using a LabRam800 manufactured by Horiba Joban Yvon, measurement is performed using a wavelength of 514 nm of an argon laser.

<Oxidation temperature>
TG-DTA manufactured by Max Science was used to raise the temperature at a rate of 10 ° C./min while circulating air at a flow rate of 0.1 liter / min, and the oxidation behavior of the fine carbon fiber aggregate was measured. The temperature at the top of the exothermic peak of DTA is determined as the oxidation temperature.

[Coating material]
The coating material of the present invention contains finely pulverized or fibrillated fine carbon fiber aggregates obtained by the above-described production method and an organic binder component. As the organic binder used in the present invention, (25 ° C. ± 5 ° C.) may be liquid or solid, and various known ones may be used depending on the application.

  Specifically, for example, acrylic resins, alkyd resins, polyester resins, polyurethane resins, epoxy resins, phenol resins, melamine resins, amino resins, vinyl chloride resins, silicones commonly used for solvent-based paints and oil-based printing inks Resin, rosin resin such as gum rosin, lime rosin, maleic acid resin, polyamide resin, nitrocellulose, ethylene-vinyl acetate copolymer resin, rosin modified phenolic resin, rosin modified resin such as rosin modified maleic resin, petroleum resin, etc. be able to. For water-based paints and water-based inks, water-soluble acrylic resins, water-soluble styrene-maleic acid resins, water-soluble alkyd resins, water-soluble melamine resins, water-soluble urethane emulsion resins, water-soluble epoxy resins, water-soluble polyester resins Etc. can be used.

  Further, in the conductive coating material according to the present invention, in addition to the organic binder component and the carbon fiber aggregate as described above, a solvent, fats and oils, an antifoaming agent, a dye, a pigment or an extender pigment, etc. Additives such as colorants, drying accelerators, surfactants, curing accelerators, auxiliaries, plasticizers, lubricants, antioxidants, ultraviolet absorbers, and various stabilizers may be blended.

  Solvents include soybean oil, toluene, xylene, thinner, butyl acetate, methyl acetate, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether commonly used for solvent-based paints or inks. Such as glycol ether solvents such as ethyl acetate, butyl acetate and amyl acetate, aliphatic hydrocarbon solvents such as hexane, heptane and octane, alicyclic hydrocarbon solvents such as cyclohexane, mineral spirits, etc. Petroleum solvents, ketone solvents such as acetone and methyl ethyl ketone, alcohol solvents such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, aliphatic hydrocarbons, and the like can be used.

  Water-based paint solvents include water and alcohol solvents such as ethyl alcohol, propyl alcohol, and butyl alcohol, and glycols such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, and butyl cellosolve that are commonly used for water-based paints and inks. Ether solvents, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol and other oxyethylene or oxypropylene addition polymers, ethylene glycol, propylene glycol, 1,2,6-hexanetriol, etc. It can be used by mixing with a water-soluble organic solvent such as alkylene glycol, glycerin, 2-pyrrolidone and the like.

  As oils and fats, boil oils obtained by processing dry oils such as linseed oil, persimmon oil, sea lion oil, safflower oil and the like can be used.

  Conventionally, these conductive coatings have also been used as antifoaming agents, coloring agents, drying accelerators, surfactants, curing accelerators, auxiliary agent plasticizers, lubricants, antioxidants, UV absorbers, various stabilizers, and the like. Various known materials used can be used as the material.

  The coating material of the present invention contains the above-mentioned fine carbon fiber aggregate together with the organic binder component as described above. The content of the fine carbon fiber aggregate varies depending on the application of the coating material, the type of the organic binder component, etc., but is preferably 0.01 to 50% by mass, particularly preferably 0.1 to 30% by mass in the coating material. .

  As a method for preparing the coating material of the present invention, various wet or dry mixing methods can be used. Moreover, in order to further improve the quality stability of the obtained conductive coating material, a step of removing coarse particles by performing a centrifugal treatment or a filter treatment may be provided.

  Hereinafter, the present invention will be described more specifically based on examples.

Example 1
An aggregate of fine carbon fiber structures was synthesized by CVD using toluene as a raw material.

  A mixture of ferrocene and thiophene was used as a catalyst, and the reaction was performed in a hydrogen gas reducing atmosphere. Toluene and the catalyst were heated to 380 ° C. together with hydrogen gas, supplied to the production furnace, and thermally decomposed at 1300 ° C. to obtain an aggregate of fine carbon fiber structures (first intermediate). FIGS. 1 and 2 show SEM and TEM photographs observed after the first intermediate was dispersed in toluene and the sample for the electron microscope was prepared.

  The synthesized first intermediate was fired in nitrogen at 900 ° C. to separate tar and the like, and a fine carbon fiber structure (second intermediate) used for pulverization and / or defibration was obtained.

  The aggregate of the fine carbon fiber structure (second intermediate) thus obtained was pulverized and / or defibrated with New Microcyclomat (trade name, manufactured by Masuno Seisakusho) MCM-3 type. did. The air supply rate is 700 L / min, the aggregate carbon fiber structure (second intermediate) aggregate supply rate is 120 g / hr, the groove inclination angle is 15 °, and the pressure is changed at a rotor rotation speed of 10,880 rpm. I did it. The photograph which observed the aggregate | assembly of the pulverized and / or fibrillated carbon fiber structure with an optical microscope is shown in FIG.

The aggregate of fine carbon fiber structures obtained by pulverization and / or defibration in this manner was subjected to high-temperature heat treatment (annealing) at 2400 ° C. in argon. The aggregate of fine carbon fiber structures thus obtained had an equivalent circle average diameter of 140 μm and a bulk density of 0.0029 g / cm ³ . A TEM photograph of the obtained fine carbon fiber structure is shown in FIG.

(Comparative Example 1)
In Example 1, an aggregate of fine carbon fiber structures is obtained by performing the same operation as in Example 1 except that the order of the pulverization and / or defibration process and the high-temperature heat treatment (annealing) process is reversed. It was. The resulting fine carbon fiber structure aggregate had an equivalent circle diameter of 200 μm and a bulk density of 0.0052 g / cm ³ . In addition, FIG. 5 shows an optical micrograph of the obtained carbon fiber structure aggregate dispersed in toluene with ultrasonic waves and observed after preparing a sample for an electron microscope.

(Example 2)
The fine carbon fiber structure aggregate was adjusted so that the content of the fine carbon fiber structure aggregate obtained in Example 1 was 0.5 mass%, 1.0 mass%, and 2.0 mass%. , 10 g of epoxy resin (Adeka Resin EP4100E, epoxy equivalent 190, manufactured by Asahi Denka Kogyo Co., Ltd.), a curing agent (Adeka Hardener EH3636-AS, manufactured by Asahi Denka Kogyo Co., Ltd.), kneaded for 10 minutes, and coating material Prepared.

  This coating material was formed into a film using a doctor blade with a gap of 200 μm. After curing at 170 ° C. for 30 minutes, the aggregate due to the aggregate of fine carbon fiber structures in the coating film was visually observed. The results of measuring the surface resistance value of the coating film are shown in Table 1.

(Comparative Example 2)
In Example 2, instead of using the aggregate of the fine carbon fiber structure obtained in Example 1, instead of using the aggregate of the fine carbon fiber structure obtained in Comparative Example 1, Example 2 and The same operation was performed to prepare a coating film. The aggregate resulting from the aggregate | assembly of the fine carbon fiber structure in a coating film was visually observed. The results of measuring the surface resistance value of the coating film are shown in Table 1.

2 is a SEM photograph of an intermediate of the carbon fiber structure obtained in Example 1. 2 is a TEM photograph of an intermediate of a carbon fiber structure obtained in Example 1. 2 is an optical micrograph of an aggregate of carbon fiber structures after pulverization and / or defibration and before annealing in Example 1. FIG. 2 is a TEM photograph of an annealed carbon fiber structure obtained in Example 1. 2 is an optical micrograph of an aggregate of carbon fiber structures obtained in Comparative Example 1.

Claims (11)

  After finely pulverizing and / or airflow defibrating a fine carbon fiber aggregate (hereinafter referred to as a fine carbon fiber aggregate to be subjected to pulverization and / or defibration) having an area-based circle equivalent average diameter of 150 μm or more, 1800 Manufacture of fine carbon fiber aggregates (hereinafter referred to as fine carbon fiber aggregates obtained by annealing after pulverization and / or defibration) having an area-based circle equivalent average diameter of less than 150 μm, which is heat-treated at 3000 ° C. Method.   The method for producing a fine carbon fiber aggregate according to claim 1, wherein the method of airflow pulverization and / or airflow defibration is a method of applying pressure fluctuation to the fine carbon fiber aggregate.   The method for producing a fine carbon fiber aggregate according to claim 1 or 2, wherein the fine carbon fiber aggregate subjected to pulverization and / or defibration is not subjected to a heat history of 1800 to 3000 ° C.   The fine carbon fiber aggregate subjected to pulverization and / or defibration is heated at 800 to 1200 ° C to remove unreacted raw materials and / or tars. The manufacturing method of the fine carbon fiber assembly as described in 2. The I _D / I _G ratio of the fine carbon fiber aggregate subjected to pulverization and / or defibration (I _D / I _G is calculated from the measured value obtained by Raman spectroscopic analysis at 514 nm of an argon laser) is 0.2. The manufacturing method of the fine carbon fiber aggregate | assembly as described in any one of Claims 1-4 which exceeds and is 1.5 or less. The fine carbon fiber aggregate obtained by annealing after pulverization and / or defibration has an I _D / _IG ratio of 0.2 or less, according to any one of claims 1 to 5. A method for producing a carbon fiber assembly.   The fine carbon fiber aggregate used for pulverization and / or defibration is an aggregate of three-dimensional network-like carbon fiber structures composed of carbon fibers having an outer diameter of 15 to 100 nm, and the carbon fiber structure Is a carbon fiber structure in which a plurality of the carbon fibers are extended, have a granular part that bonds the carbon fibers to each other, and the granular part is formed during the growth process of the carbon fiber. The manufacturing method of the fine carbon fiber assembly as described in any one of Claims 1-6. The fine carbon fiber aggregate according to any one of claims 1 to 7, wherein a bulk density of the fine carbon fiber aggregate subjected to pulverization and / or defibration is 0.0001 to 0.05 g / cm ^3. Body manufacturing method.   In the carbon fiber bonding portion in the carbon fiber structure constituting the fine carbon fiber aggregate subjected to pulverization and / or defibration, the particle size of the granular portion is larger than the outer diameter of the carbon fiber. The manufacturing method of the fine carbon fiber aggregate | assembly of Claim 7 or 8.   The fine carbon fiber aggregate subjected to pulverization and / or defibration is produced using at least two or more carbon compounds having different decomposition temperatures as a carbon source. The manufacturing method of the fine carbon fiber aggregate | assembly as described in one.   A fine carbon fiber aggregate obtained by annealing after airflow pulverization and / or airflow defibration obtained by the production method according to any one of claims 1 to 10 and an organic binder are contained. And coating material.