JP5470513B2 - Carbon composite material manufacturing method - Google Patents

Description

The present invention relates to a method for producing a carbon composite material .

  In recent years, with the development of nanotechnology, various new composite materials have been developed. One of these is a material (hybrid material) as a composite that attaches and fixes ultrafine metal particles (metal nanoparticles) to a material such as a carbon nanotube (CNT), such as carbon nanotubes. Since it is expected to have excellent physical properties such as chemical characteristics and mechanical characteristics, it is required to develop an industrial material having an efficient productivity method and a new application associated therewith.

  Conventionally, as a technique for fixing a metal to a carbon nanotube, for example, those described in Patent Document 1 and Patent Document 2 are known. The technology described in Patent Document 1 is a hybrid carbon nanotube in which metallic ultrafine particles are encapsulated inside the carbon nanotube, and this makes it possible to provide a composite material that can be used in fields such as information communication and chemical industry. However, the technique of Patent Document 1 does not have a configuration in which ultrafine metal particles are attached to the surface of the carbon nanotube.

  The carbon nanotube described in Patent Document 2 forms an opening or a defect on the surface of the carbon nanotube by oxidation treatment, attaches a metal catalyst precursor to the inside and outside of the carbon nanotube, and then reduces the inside and The metal catalyst is fixed on the outer surface, but it is not a method of attaching metal ultrafine particles. Accordingly, there is no known metal fine particle adhesion method or metal fine particle-attached carbon material in which metal fine particles adhere to the surface of a carbon material such as carbon nanotubes to be solidified. In the technique of Patent Document 2, the surface of the carbon nanotube is oxidized, washed and dried, and then the oxidation catalyst is supported. Also, the precursor of the metal catalyst is mixed by washing and drying, and further reduction treatment is performed. There is a problem that a considerable process is required such as.

  On the other hand, Patent Documents 3 to 6 disclose a technique of composite metal ultrafine particles in which metal ultrafine particles are used as a core metal and surrounded by an organometallic compound. That is, the composite metal ultrafine particles described in Patent Document 3 surround a metal component such as silver in the center with a metal organic compound such as silver stearate to form composite metal ultrafine particles. The composite metal ultrafine particles have an average particle size of 1 to 100 nm, and in an inert gas atmosphere in which air is shut off, at a temperature higher than the decomposition start temperature of the metal organic compound and lower than the complete decomposition temperature. By heating, it is possible to produce composite metal ultrafine particles having excellent dispersion stability.

  In addition, the ultrafine composite metal particles of Patent Document 4 have a configuration in which a core metal such as silver is surrounded by an ionic organic substance that is a fatty acid having 5 or more carbon atoms. It is heated at a temperature equal to or higher than the decomposition reduction temperature and lower than the decomposition temperature of the ionic organic substance. Thereby, the particle diameter is uniform, the dispersion stability is excellent, and it can be produced on an industrial scale.

In Patent Document 7, cage-like carbon nanotubes aggregated in an organic solvent are dispersed, further cut into a substantially uniform length, aligned, loosened and mixed with another substance. A technique for increasing the dispersion efficiency is described. This includes a plurality of first processing passages (grooves / flow paths) formed by the upstream first plate member, and a plurality of second processing paths (grooves / flow paths) formed by the downstream second plate member. Is a dispersive device in which the collision parts are formed by mutually orthogonally connecting them. As a result, when the carbon nanotube-carrying liquid pressurized by the pressurizing device is pumped from the supply nozzle to the two first processing passages and flows into the second processing passage, the liquid-bearing liquid is arranged in the above-described orthogonal arrangement. The turbulent flow, the high-speed flow, the ultrasonic wave, the shock wave, the cavitation, and the like are generated by colliding at the colliding portion and changing the flow path, and are uniformly dispersed by the energy.
JP 2002-97009 A JP 2006-334527 A Japanese Patent Laid-Open No. 10-183207 JP 2001-131603 A JP 2002-363127 A International Publication No. 2000-76699 JP 2006-16222 A

  However, as described above, although the techniques of Patent Documents 3 to 6 disclose a method of obtaining composite metal ultrafine particles that are convenient to handle by fixing an organic compound around a core metal, There is no specific description regarding the technique of attaching to the surface of carbon materials, such as a nanotube. In addition, there is no technique relating to means using the technique described in Patent Document 7 in the manufacturing process in which ultrafine metal particles are attached to the surface of a carbon material.

As a result of research and development, the present applicant has obtained knowledge about a method for producing a carbon composite material in which ultrafine metal particles are attached to a carbon material such as a carbon nanotube.

The present invention is excellent in various aspects such as physical characteristics, chemical characteristics, mechanical characteristics, etc., by efficiently attaching and fixing ultrafine metal particles to the surface of a carbon material based on the knowledge obtained by such research and development. An object of the present invention is to provide a method for producing a carbon composite material having excellent physical properties.

(1) The method for producing a carbon composite material according to the present invention comprises an organic composite metal formed by coating ultrafine metal particles with an organic compound having an alkyl group on the surface and a functional group having reactivity with the metal surface. After the nanoparticles are dispersed and solubilized in an organic solvent, and the carbon material is stirred and mixed in the organic solvent containing the organic composite metal nanoparticles, the organic solvent is dried by heat treatment, and the organic composite metal nanoparticles By decomposing the organic coating surrounding the ultrafine metal particles, the ultrafine metal particles are integrated in a form that reacts or erodes the carbon material, and the organic compound covering the ultrafine metal particles has 5 carbon atoms. To 22 linear fatty acids or linear higher alcohols having 5 to 22 carbon atoms, and the organic solvent is a chain or cyclic such as toluene, hexane, or cyclohexane Which comprises using a hydrocarbon comprising aromatic.

  According to the present invention, an organic composite metal nanoparticle in which an organic substance is bonded to a metal core (ultrafine particle) is used. That is, it is a method for attaching ultrafine metal particles using metal nanoparticles in a chemically bonded state.

  In the present invention, a mixture of organic composite metal nanoparticles dispersed and solubilized in an organic solvent and the carbon material is used and stirred and mixed. Since the organic composite metal nanoparticles are solubilized in the solvent, they are mixed and mixed with the carbon material and adhere to the carbon material while maintaining the dispersed state. By subjecting this mixture to heat treatment, the solvent is dried, and the organic coating surrounding the ultrafine metal particles is decomposed and blown, whereby the ultrafine metal particles can be directly bonded onto the carbon material. As a result, it is possible to obtain a carbon material to which metal ultrafine particles are adhered and fixed. Preferably, the carbon material is dispersed in advance using the same organic solvent as the organic solvent in which the ultrafine metal particles are dispersed, and the organic solvents are mixed together.

  (2) Further, the carbon material of the present invention is any one of carbon nanotubes, carbon fibers, graphite, activated carbon, coke, carbon black, carbon graphite, and diamond.

  It is possible to adhere metallic ultrafine particles to these carbon materials more reliably. In particular, it is preferable to use carbon nanotubes (CNT) as the carbon material. By attaching the ultrafine metal particles to the surface of the carbon nanotube, the ultrafine metal particles are fixed in a state of bulging from the surface of the carbon nanotube. For example, if the carbon nanotube surface swells in a granular form (substantially spherical body), the surface area occupied by the ultrafine metal particles increases due to the unevenness. For this reason, for example, when the metal ultrafine particles are a metal such as silver, it is possible to obtain a carbon material with attached metal ultrafine particles having excellent electromagnetic wave shielding characteristics, and is strong against tensile external force if mixed into a synthetic resin material. An ultrafine metal particle-attached carbon material can be obtained, and if applied to an exhaust gas purifying apparatus such as a trap collecting device having a honeycomb structure such as a vehicle, an ultrafine metal particle-attached carbon material exhibiting a catalytic function can be obtained. For this reason, it becomes possible to obtain an ultrafine metal particle-attached carbon material having excellent physical properties such as physical characteristics, chemical characteristics, and mechanical characteristics.

  The carbon nanotube can be applied to both single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWCNT). In the case of multi-walled carbon nanotubes, the size balance between the ultrafine metal particles and the diameter of the multi-walled carbon nanotubes becomes good, and the bonding state of the ultrafine particles can be firmly maintained when the ultrafine metal particles are attached. Therefore, a more preferable carbon composite material to which metal ultrafine particles are adhered can be obtained.

  (3) Further, the ultrafine metal particles of the present invention are any one of platinum, gold, silver, nickel, iron, and copper. Above all, it is preferable to use silver, and by using such means, a composite of silver nanoparticles and carbon nanotubes can be produced.

  (4) As the organic solvent used in the present invention, an organic solvent that well solubilizes the organic composite metal nanoparticles can be used. In the present invention, the organic compound that coats the ultrafine metal particles has a carbon number. It is preferably a linear fatty acid having 5 to 22 or a linear higher alcohol having 5 to 22 carbon atoms, and the organic solvent is preferably a chain, cyclic, or aromatic hydrocarbon such as toluene, hexane, or cyclohexane. .

  According to such a method, the organic composite metal nanoparticles are monodispersed in the organic solvent, thereby becoming a solubilized dispersion solution: suspension like a true solution. An unsaturated hydrocarbon can also be used as the organic solvent. In some cases, various terpenes can be used.

  (5) The present invention is also characterized in that ultrasonic waves are used as a stirring and mixing means for stirring and mixing the organic solvent and the carbon material.

  According to such means, the solubilized state of the ultrafine metal particles coated with an organic compound having an alkyl group on the surface and a functional group having reactivity with the metal surface is maintained. It becomes possible to adhere evenly to the surface of the material.

  (6) In the present invention, as the stirring and mixing means for stirring and mixing the organic solvent and the carbon material, a pressure applying device that applies pressure to the organic solvent, and the organic that is pressurized by the force applying device By using a device comprising a plurality of introduction flow channels for introducing a solvent and a collision part for causing the organic solvent that has flowed through the introduction flow channel to collide with each other, by changing the flow direction by colliding the organic solvent Turbulent flow, high-speed flow, ultrasonic wave, shock wave, cavitation, and the like are generated and mixed by stirring. As described above, energy is generated by mechanical external force, and the organic solvent is stirred and mixed by the energy, so that the ultrafine metal particles can be evenly attached to the surface of the carbon material in a very short time.

  (7) Further, in the present invention, the heat treatment for drying the organic solvent is performed in an atmosphere or an environment at a pressure lower than atmospheric pressure, and the temperature of the heat treatment is equal to or higher than a temperature at which the organic compound is decomposed. It is below the temperature which the said carbon material decomposes | disassembles, It is characterized by the above-mentioned.

  According to such means, when the mixture after stirring and mixing is heated, the solvent is heated by heating at a temperature not higher than the temperature at which the carbon nanotubes are melted and decomposed, and at a temperature not lower than the temperature at which the fatty acid is decomposed. It is dried, and the organic film surrounding the metal ultrafine particles is decomposed and blown off. Thereby, metal ultrafine particles can be effectively attached to the carbon material. Moreover, by making the environment low pressure, the particle size of the ultrafine metal particles that aggregate and adhere to the surface of a carbon material such as carbon nanotubes can be reduced so as not to become too large. That is, it can be controlled to suppress the enlargement of the ultrafine metal particles.

  (8) In the present invention, the carbon material is once dispersed in another solvent in advance, and then the carbon material is mixed in the organic solvent containing the organic composite metal nanoparticles, and the carbon As dispersion means for predispersing the material in the solvent, a pressure applying device that applies pressure to the solvent, a plurality of introduction flow channels that introduce the solvent pressurized by the pressure applying device, and the introduction flow By using a device comprising a collision unit that collides the solvent that has flowed through the path with each other, by changing the flow direction by colliding the solvent containing the carbon material, turbulent flow, high-speed flow, ultrasonic waves, A shock wave, cavitation or the like is generated to disperse the carbon material.

  By using such means, the length of the carbon nanotubes, which are entangled and aggregated in a cage shape, is dispersed using a solvent by the energy of shock waves, ultrasonic waves, shearing force, cavitation, etc. generated by the collision action, and the length is increased. It becomes possible to homogenize and disperse uniformly in the solvent. As a result, the metal ultrafine particles can be efficiently fixed in a uniformly dispersed state to each carbon material, not to a lump of carbon material. In addition, the said solvent used when disperse | distributing a carbon raw material previously is not restricted to an organic solvent, It is possible to use various solvents, such as water.

  In the present invention, the particle size of the ultrafine metal particles can be made smaller than the diameter or smaller than the radius of the carbon nanotube. The ultrafine metal particles adhering to the carbon material are formed by agglomerating one or more of the added organic composite metal nanoparticles, and the particle diameter should be controlled to be equal to or less than the diameter of the carbon nanotube. Thus, the ultrafine metal particles that aggregate on the surface of the carbon nanotubes can reduce the degree of erosion on the surface of the carbon nanotubes, and can uniformly disperse and adhere while suppressing the deterioration of the properties of the carbon material such as carbon nanotubes.

  (9) In the present invention, the metal ultrafine particles adhering to the surface of the carbon material or the carbon nanotube are removed by heating or external force, and the carbon material or the carbon nanotube is eroded to form irregularities on the surface. It is characterized by being.

  According to such means, the ultrafine metal particles adhering to the carbon nanotubes fall out by causing an excessive reaction (heating). Thereby, the carbon nanotube is eroded and irregularities are formed on the surface thereof. For this reason, when synthetic resin etc. are mixed in the unevenness | corrugation, for example, synthetic resin penetrates so that it may bite. As a result, the slip resistance between the synthetic resin and the carbon nanotube increases, and the binding force with the synthetic resin can be increased.

  Note that the carbon composite material to which the ultrafine metal particles are attached can be used as, for example, an electromagnetic shielding material. For example, electromagnetic interference can be avoided by installing this material in a portion that shields electromagnetic waves emitted from an ignition device in a mobile phone, electronic equipment, ETC, automobile engine room, or the like.

  It is also possible to use the carbon composite material to which the metal ultrafine particles have been adhered by mixing it in a resin. In this way, the attached metal ultrafine particles are easily caught by the resin, so that the metal ultrafine particles function as a slip resistance element. As a result, the slip resistance between the carbon material and the resin increases, and the mechanical properties of the resin Strength can be increased.

  Further, the carbon composite material to which the ultrafine metal particles are adhered can be used as a catalyst for exhaust gas treatment and a catalyst for a fuel cell electrode. In various exhaust gas treatment apparatuses, metal ultrafine particles are applied as a catalyst, but the inefficiency of the application is a problem. Therefore, by using the carbon composite material to which the ultrafine metal particles of the present invention that have been dispersed in a carbon material and fixed with ultrafine metal particles are attached in advance, the ultrafine metal particles can be efficiently disposed over a wide surface area. Since the amount of the material used can be reduced, it is possible to realize an inexpensive exhaust gas purification and to obtain an efficient exhaust gas purification function. In addition, the carbon composite material to which the ultrafine metal particles have been attached has the characteristics that the carbon nanotubes have high strength and are not easily deteriorated, and the ultrafine metal particles are firmly adhered to the carbon nanotubes. It can also be used as a catalyst for good fuel cell electrodes.

According to the present invention, it is possible to stably and efficiently adhere ultrafine metal particles to a carbon material such as a carbon nanotube in various states such as physical, chemical, and mechanical properties. A new carbon composite material with excellent physical properties can be obtained .

  Hereinafter, the best mode for carrying out a method for attaching ultrafine metal particles according to the present invention and an ultrafine metal particle-attached carbon material using the same will be described with reference to the drawings.

  FIG. 1 is a process diagram showing a method for attaching metal ultrafine particles in the present embodiment. The adhesion of ultrafine metal particles consists of the following steps. In step S1, ultrafine metal particles (organic composite metal nanoparticles) coated with an organic compound having an alkyl group on the surface and a functional group having reactivity with the metal surface are dispersed and solubilized in an organic solvent. As the organic solvent, an organic solvent that well solubilizes the organic composite metal nanoparticles can be used, and in particular, various saturated hydrocarbons including chain, cyclic, and aromatic such as toluene, hexane, and cyclohexane are used. Although preferred, unsaturated hydrocarbons can also be used. In some cases, various terpenes can be used.

  In step S2, the mixture is stirred by a stirring means such as a stirrer or an ultrasonic wave until the precipitate disappears.

  On the other hand, in parallel with these, in step S3, using the same organic solvent as used in step S1, the carbon material is dispersed using, for example, a dispersion apparatus described in Patent Document 6. As shown in FIG. 2, the dispersing device 100 includes a pressure applying device 110 that applies pressure to the organic solvent, and a plurality (two in this case) of introducing the organic solvent pressurized by the pressure applying device. The flow path 120A, 120B, the collision part 122 that causes the organic solvent that has flowed through the introduction flow paths 120A, 120B to collide with each other, and a plurality of (here, two) lead-out flow paths 124A that lead out the collided solvent. , 124B. Therefore, the pressurized carbon material-supporting organic solvent is collided at the collision part 122 which is a narrow space, and the flow path is changed to generate turbulent flow, high-speed flow, ultrasonic wave, shock wave, cavitation, etc., and its energy To disperse the carbon material.

  The reason why it is convenient to use the dispersion device 100 is that when the carbon material is carbon nanotubes or carbon fibers, the aggregates of the carbon nanotube groups and carbon fiber groups that are aggregated and entangled are broken down to some extent. This is because it can be dispersed while being divided into a uniform shape and length. By breaking the lump, the metal ultrafine particles can be attached one by one in the next step. In addition, other carbon materials such as carbon black, carbon graphite, coke, graphite, and activated carbon often cause secondary aggregation. This is because, by using the dispersion device 100 in step S3 to redisperse to the primary particle diameter, the metal fine particles can be attached to the carbon material of each primary particle in the next step.

  In step S4, the organic composite metal nanoparticle dispersion solvent in step S2 and the carbon material dispersed by the dispersion apparatus 100 in step S3 are further stirred and mixed to attach the organic composite metal nanoparticles to the carbon material. As the stirring and mixing means at this time, for example, stirring and mixing can be performed by applying an external force with a stirrer (stirrer), ultrasonic waves, a dispersing device shown in FIG. 2 or the like, or by applying vibration. The form is preferred. In particular, when the ultrafine metal particles are silver and are uniformly (uniformly) adhered to the surface of the carbon nanotube, it is most preferable to use ultrasonic waves. Further, it is of course possible to use the dispersion apparatus 100 of FIG. 2, and stirring and mixing can be completed in a short time. The stirring and mixing time in step S4 is about 15 minutes to 30 minutes. The effect does not change much even if the stirring and mixing time is prolonged. In particular, according to the method using the ultrasonic wave or the dispersion device 100, it is possible to uniformly attach the ultrafine metal particles to the carbon material.

  In step S5, the solvent is removed by filtration with filter paper. In step S6, the carbon material with the ultrafine metal particles remaining on the filter paper is dried, and in the heat treatment process in step S7, the protective film that is a fatty acid such as stearic acid is blown by an oven or the like. It is desirable that the heating temperature is in a range not less than the temperature at which the organic compound of the protective film material is decomposed (for example, 200 ° C. for fatty acids) and not more than the temperature at which each carbon material is decomposed. Moreover, it is preferable to heat in a heating atmosphere pressure lower than atmospheric pressure. In this case, it is good to carry out in the atmosphere. Further, it may be performed in a nitrogen gas atmosphere. It is also considered to be performed under reduced pressure. This is because aggregation of metal ultrafine particles, that is, enlargement of metal can be suppressed. During the heating, the surface of the carbon material is integrated with the ultrafine metal particles by reaction and erosion due to the effects of temperature and time.

  In this way, in step S8, the metal ultrafine particle-attached carbon composite in which the metal ultrafine particles are firmly attached to the carbon material can be obtained.

  Hereinafter, examples in which the method for attaching ultrafine metal particles in the above embodiment is specifically described will be described.

  Example 1 of a carbon ultrafine particle-adhered carbon material that has been experimentally produced using the above method for attaching ultrafine metal particles will be described. In the following examples, unless otherwise specified, multi-walled carbon nanotubes are used as the carbon material, and silver nanoparticles are used as the metal in the organometallic compound.

  In Example 1, ultrasonic waves are used as the stirring and mixing means in the above step S6, the silver irradiation particles are attached to the carbon nanotubes by changing the irradiation time of the ultrasonic waves, and a composite of the silver nanoparticles and the carbon nanotubes is formed. I was able to get it. The composite shown in the electron micrograph of FIG. 3 has an ultrasonic irradiation time of 15 minutes, FIG. 4 is set to 30 minutes, FIG. 5 is set to 45 minutes, FIG. 6 is set to 1 hour, and FIG. It is obtained. According to these, it can be seen that silver nanoparticles are uniformly and evenly attached even to the region where the carbon nanotubes are densely packed. On the other hand, from these results, since the degree of adhesion of the nanoparticles does not change depending on the ultrasonic irradiation time, ultrasonic irradiation can effectively and uniformly attach the ultrafine metal particles to the carbon material in a short time. understood.

  Example 2 uses the dispersion apparatus 100 of FIG. 2 as the stirring and mixing means in step S6, and changes the applied pressure and the number of treatments (number of collisions) to attach silver nanoparticles to the carbon nanotubes. Thus, a composite of silver nanoparticles and carbon nanotubes was obtained. The working pressure was 50 Mpa, 100 Mpa, 150 Mpa, and the number of times was 1, 3 and 5 times, respectively. As shown in FIG. 8, it was confirmed that the silver nanoparticles were uniformly and satisfactorily adhered even after a single treatment at 50 MPa, which is a low pressure (low energy). Although not specifically illustrated, the degree of nanoparticle adhesion did not change even when the pressure was increased or the number of treatments was repeated. Therefore, as in the case of the ultrasonic irradiation, if the dispersion treatment 100 is used, the mixing treatment is performed. It was found that the ultrafine metal particles can be effectively and uniformly attached to the carbon material.

  In Example 3, a composite was obtained using a stirrer as a stirring and mixing means. As shown in FIG. 9, there are fine nanoparticles and large nanoparticles, and the adhesion is sparse. . As a result, this Example 2 was also able to obtain a nanosilver-adhered composite in which silver nanoparticles were adhered to the surface of the carbon nanotube by applying an external force.

  In Example 4, a composite was obtained by applying an external force by handshaking as stirring and mixing means. As shown in FIG. 10, silver nanoparticles are attached to the carbon nanotubes, but are attached in a sparse state. In addition, there are portions where silver nanoparticles are largely agglomerated to form large lumps, and other portions are not. As a result, also in Example 4, it is possible to obtain a composite in which silver nanoparticles are well adhered to carbon nanotubes.

  In Example 5, a composite was obtained without using a stirring and mixing means and without doing anything. As shown in FIG. 11, there are many places where silver nanoparticles are attached and places where silver nanoparticles are not attached, and the adhesion to carbon nanotubes is thin. In addition, it seems that there are many fine nanoparticles, and on the other hand, there are also a lot of nano particles, and when compared with Examples 1 to 3 above, the nanoparticles adhere to the carbon nanotubes, but the uneven adhesion state It can be seen that

  In Example 6 to Example 9 below, the carbon material is replaced with a carbon material other than carbon nanotubes, the stirring and mixing in Step S4 is performed with ultrasonic waves, and the heating in Step S7 is performed over a predetermined time. It is an example.

  That is, Example 6 is a case where silver nanoparticles are attached to graphite, and as shown in FIGS. 12 and 13, it can be seen that the nanoparticles are uniformly attached to the surface of the graphite, and a good composite is obtained. I was able to get a body.

  Example 7 is an example in which CB (carbon black) was used as a carbon material, and silver nanoparticles were adhered thereto. As shown in FIGS. 14 and 15, it was found that the nanoparticles were adhered to the surface of CB in a good state, and a good composite could be obtained.

  Example 8 is a case where CG (carbon graphite) is used as a carbon material, and silver nanoparticles are well adhered to the CG surface as shown in FIGS. 16 and 17 in a uniform manner. The situation was understood and a good composite could be obtained.

  Example 9 is an example in which activated carbon was used as the carbon material. As shown in FIGS. 18 and 19, it was possible to obtain a composite that was well adhered to the surface of the activated carbon in a state where silver nanoparticles were uniformly dispersed.

  As mentioned above, the composite_body | complex in which the nanoparticle of silver can adhere in the favorable state was obtained with respect to any carbon raw material of Example 6-9.

  Examples 10 to 12 are examples in which a dispersant is mixed in a solution in which ultrafine metal particles are dispersed and solubilized in an organic solvent in step S2 in the process of attaching silver nanoparticles to carbon nanotubes. It is.

  In Example 10, since stearic acid is cationic, an appropriate amount of cationic octylamine was added. As a result, as shown in FIG. 20, it was found that a composite in which silver nanoparticles were adhered to the surface of the carbon nanotube in a good state was obtained, and the dispersion stability by amine was excellent and effective. The same effect can be obtained by adding an appropriate amount of octylamine, pentylamine, propylamine to the solvent during the pre-dispersion of carbon materials such as carbon nanotubes in step S3, and then substituting the solvent with toluene, hexane, cyclohexane or the like. It was.

  Example 11 is an example in which Olphine manufactured by Nissin Chemical Co., Ltd. was used as a nonionic dispersant. As a result, as shown in FIG. 21, a composite having a slightly lower degree of silver nanoparticles than Example 10 was obtained, and it was found that the nonionic system was also useful as a dispersant.

  Example 12 is an example using a polymer-based dispersant, and a composite as shown in FIG. 22 was obtained. Unlike the case of Example 10 and Example 11, the adhesion of nanoparticles is considerably weakened. This seems to be caused by the polymer-based dispersant covering the carbon nanotube surface.

  Comparing the composites of Examples 10 to 12, it can be considered that it is preferable to mix a cationic dispersant in a solvent such as toluene in order to aggregate silver nanoparticles into carbon nanotubes.

  In addition, as a dispersing agent, if it is a dispersing agent which can carry out aggregation adhesion of a nanoparticle, an appropriate surfactant can also be used.

  As Example 13, the drying / heating method in Steps S6 and S7 was examined. This is because when the heating temperature is insufficient, the decomposition of stearic acid, which is an organic film surrounding the metal ultrafine particles, becomes insufficient, and silver does not precipitate from the organic film. Therefore, a method of heating slowly (15 ° C./min) and heating for 30 minutes and a method of heating in a certain temperature state for 30 minutes or 60 minutes at a stretch were performed. The results are shown in Table 1.

The content rate of stearic acid in the silver nanoparticle raw material converted into the organometallic compound is about 25% by weight. Assuming this, since stearic acid is decomposed in the heating process of step S7, the weight corresponding to the content decreases. Examining Table 1 based on this idea, it was found that heating at a temperature of 230 ° C. to 250 ° C. for 30 minutes is effective in attaching silver nanoparticles to the carbon nanotubes, and is desirable.

  On the other hand, as can be seen from Table 1, when the heating temperature reaches 280 ° C., the reduced weight is a value that deviates far from 25%, so that the weight more than the content of stearic acid burns and decreases. You can see that Therefore, when the state after heating to 280 ° C. for 30 minutes at a stretch was confirmed with an electron microscope, the state in which the silver nanoparticles eroded the carbon nanotube surface as shown in FIG. 23 could be determined. Similarly, when heated at 250 ° C. for 1 hour, the weight of stearic acid content or more decreased from Table 1, and as shown in FIG. 24, the surface of the carbon nanotube began to erode even with an electron microscope. confirmed.

  On the other hand, when the temperature of the silver nanoparticles was compared between the case where the temperature was raised slowly and the case where the temperature was heated at once, it was found that the silver nanoparticles can be finely adhered when heated at a stroke. This is probably because stearic acid is gradually heated from a low temperature and decomposes in the case where the temperature is slowly raised, and silver starts to aggregate in the process.

  Example 14 is an example based on the knowledge of Example 13 above. When the heating temperature was heated to 280 ° C. or higher to promote the adhesion reaction, the composite of Example 14 shown in FIGS. 25 and 26 could be obtained. This complex is in a state that cannot occur at 230 ° C. or lower, that is, a state in which silver nanoparticles have eroded carbon nanotubes and have holes. The holes include a hole from which silver nanoparticles are removed and a hole in which silver nanoparticles are present. The surface of the carbon nanotube as a whole has an uneven shape due to the holes. As well shown in FIG. 26, in the hole to which the silver nanoparticles are adhered, the nanoparticles are developed and adhered to the inside of the carbon nanotube. From this, it can be considered that the method for attaching ultrafine metal particles according to the present invention is not physical adsorption but causes some kind of chemical bond.

  In Example 15, the temperature was slowly raised to 230 ° C. (15 ° C. increased for 1 minute) to prepare a carbon nanotube composite with metal ultrafine particles, and then external force was applied by grinding in a mortar for 15 minutes. Observation of this result reveals that most of the ultrafine metal particles remain without dropping off, as shown in FIG. Therefore, it turns out that it couple | bonds with the carbon nanotube with sufficient intensity | strength.

  In Example 16, similarly, the temperature was slowly increased to 230 ° C. (15 ° C. increased for 1 minute) to produce a carbon nanotube composite with metal ultrafine particles attached thereto, followed by ultrasonic irradiation for 30 minutes to apply vibration. When this result was observed, as shown in FIG. 28, the metal ultrafine particles did not fall out and were well dispersed and adhered.

  From Examples 15 and 16 above, the composite subjected to the heat treatment at the optimum temperature (230 ° C.) for the optimum time (30 minutes) strongly adheres to the carbon nanotubes even when such a strong external force is applied. It was confirmed that it would not fall out. From the result of this verification, it is considered that the metal ultrafine particles are attached not by simple physical adsorption but by some chemical bond.

  In Example 15, the carbon nanotube was replaced with CG (carbon graphite) and heated at 280 ° C. or higher to obtain the composite shown in FIG. Also in the case of CG, a composite in which holes are formed and silver nanoparticles are attached inside the holes can be obtained.

  As can be seen from the above Example 14 and Example 17, it is possible to remove the silver on the surface of the carbon material by heating or external force, and to form irregularities on the surface.

  Example 18 and Example 21 described later are examples relating to composites obtained in order to study the adhesion of silver nanoparticles by variously changing the diameter of carbon nanotubes.

  Example 18 is an example in which carbon nanotubes having a diameter of 1 nmφ were used. As shown in FIG. 30 and FIG. 31, silver nanoparticles aggregated as a lump larger than the diameter of carbon nanotubes, and carbon It is not attached to the nanotube. Such a complex cannot be said to be a complex intended by the present invention.

  In Example 19, the diameter of the carbon nanotube is 60 nmφ. As shown in FIGS. 32 and 33, it was possible to obtain a composite in which silver nanoparticles smaller than the diameter adhered well to the carbon nanotube surface.

  Example 20 shown in FIGS. 34 and 35 is a composite when the diameter of the carbon nanotube is 100 nm. Also in Example 20, it was possible to obtain a composite in which silver nanoparticles adhered favorably to the carbon nanotube surface.

  Example 21 is a composite in which carbon nanotubes having a diameter of 20 nm to 80 nm are mixed, as shown in FIGS. 36 and 37. Also in Example 21, a composite in which silver nanoparticles were uniformly attached to the surface of the carbon nanotube could be obtained.

  As a result of comparative study of the above Examples 18 to 21, when the carbon material is a carbon nanotube, the size of the silver nanoparticles (ultrafine metal particles) is set to be equal to or less than the diameter of the carbon nanotube or less than the radius. I found it desirable. As a result, the silver nanoparticles can be uniformly dispersed and adhered to the surface of the carbon nanotubes without destroying the carbon nanotubes.

  The ultrafine metal particle adhesion method of the present invention and the ultrafine metal particle-attached carbon material using the same are not limited to the above-described embodiments and examples, and are within the scope not departing from the gist of the present invention. Of course, various changes can be made.

  That is, the metal ultrafine particle-adhered carbon material as a composite can be used as an electromagnetic shielding material. Since it absorbs or blocks electromagnetic waves emitted by the presence of ultrafine metal particles adhering to the surface of the carbon material, it can be applied to fields that require an electromagnetic wave shielding function.

  In addition, there is an application in which a carbon material with ultrafine metal particles is mixed with a synthetic resin. Since the ultrafine metal particles adhering to the surface of the carbon material are uneven, there is an advantage that the strength of the synthetic resin can be increased by slip resistance.

  In addition, there is an application in which the metal ultrafine particle-attached carbon material is used as a catalyst for exhaust gas treatment. According to this, by applying the composite to the surface of the target exhaust gas purification device (for example, a honeycomb-structured ceramic collection device), the catalytic function by the metal ultrafine particles adhering to the carbon material surface, There is an advantage that harmful components can be absorbed.

  The ultrafine metal particle adhesion method of the present invention and the ultrafine metal particle-attached carbon material using the same are new materials with excellent physical properties such as physical, chemical and mechanical properties. Therefore, it can be used in all technical fields.

It is process drawing which shows the adhesion method of the metal ultrafine particle in this Embodiment. It is a block diagram which shows schematic structure of the dispersion apparatus used with the adhesion method of the metal ultrafine particle. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 1. FIG. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 1. FIG. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 1. FIG. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 1. FIG. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 1. FIG. 2 is an electron micrograph according to the composite of Example 2. 4 is an electron micrograph according to the composite of Example 3. 4 is an electron micrograph according to the composite of Example 4. 6 is an electron micrograph according to the composite of Example 5. 4 is an enlarged electron micrograph according to the composite of Example 6. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 6. FIG. 4 is an enlarged electron micrograph according to the composite of Example 7. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 7. FIG. 4 is an enlarged electron micrograph according to the composite of Example 8. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 8. FIG. 4 is an electron micrograph according to the composite of Example 9. Similarly, it is an enlarged electron micrograph of Example 9. 2 is an electron micrograph according to the composite of Example 10. 2 is an electron micrograph according to the composite of Example 11. 4 is an electron micrograph according to the composite of Example 12. 4 is an electron micrograph according to the composite of Example 13. 4 is an electron micrograph according to the composite of Example 13. 4 is an enlarged electron micrograph according to the composite of Example 14. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 14. FIG. 2 is an enlarged electron micrograph according to the composite of Example 15. 4 is an electron micrograph according to the composite of Example 16. It is an electron micrograph which concerns on Example 17 composite. 2 is an enlarged electron micrograph according to the composite of Example 18. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 18. FIG. 2 is an electron micrograph according to the composite of Example 19. Similarly, it is the expansion electron micrograph which concerns on the composite_body | complex of Example 19. FIG. 3 is an enlarged electron micrograph according to the composite of Example 20. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 20. FIG. 2 is an enlarged electron micrograph according to the composite of Example 21. Similarly, it is the electron micrograph which concerns on the composite_body | complex of Example 21. FIG.

Claims (8)

An organic compound having an alkyl group on the surface and a functional group having reactivity with the metal surface is used to disperse and solubilize organic composite metal nanoparticles composed of metal ultrafine particles in an organic solvent. After the carbon material is stirred and mixed in the organic solvent containing the composite metal nanoparticles, the organic solvent is dried by heat treatment, and the organic coating surrounding the metal ultrafine particles in the organic composite metal nanoparticles is decomposed. Integrating the ultrafine metal particles into the carbon material in a reacted or eroded form,
The organic compound covering the ultrafine metal particles is a linear fatty acid having 5 to 22 carbon atoms or a linear higher alcohol having 5 to 22 carbon atoms, and the organic solvent is a chain such as toluene, hexane, or cyclohexane. A method for producing a carbon composite material, characterized by using a hydrocarbon containing cyclic, aromatic.   The method for producing a carbon composite material according to claim 1, wherein the carbon material is any one of carbon nanotubes, carbon fibers, graphite, activated carbon, coke, carbon black, carbon graphite, and diamond.   The method for producing a carbon composite material according to claim 1, wherein the metal ultrafine particles are any one of platinum, gold, silver, nickel, iron, and copper.   The method for producing a carbon composite material according to any one of claims 1 to 3, wherein an ultrasonic wave is used as a stirring and mixing means for stirring and mixing the organic solvent and the carbon material. As stirring and mixing means for mixing and stirring the carbon material and the organic solvent, a plurality of introduction for introducing a pressure applying apparatus for applying pressure, the organic solvent which is pressurized by the pressure applying device to the organic solvent By using a device including a flow path and a collision unit that causes the organic solvent that has flowed through the introduction flow path to collide with each other, by changing the flow direction by colliding the organic solvent, turbulent flow, high-speed flow, The method for producing a carbon composite material according to any one of claims 1 to 4, wherein ultrasonic waves, shock waves, cavitation, and the like are generated and mixed by stirring. The heat treatment for drying the organic solvent is performed in the atmosphere or in a low-pressure environment lower than atmospheric pressure, and the temperature of the heat treatment is not less than the temperature at which the organic compound is decomposed and not more than the temperature at which the carbon material is decomposed. The method for producing a carbon composite material according to claim 1, wherein: The carbon material is once dispersed in another solvent in advance, and then the carbon material is mixed in the organic solvent containing the organic composite metal nanoparticles, and
As dispersion means for predispersing the carbon material in the solvent, a pressure applying device that applies pressure to the solvent, a plurality of introduction channels that introduce the solvent pressurized by the pressure applying device, Using a device that includes a collision unit that collides the solvent that has flowed through the introduction flow path with each other, and changes the flow direction by colliding the solvent containing the carbon material, whereby turbulent flow, high-speed flow, The method for producing a carbon composite material according to any one of claims 1 to 6, wherein the carbon material is dispersed by generating sound waves, shock waves, cavitation, and the like. The unevenness is formed on the surface of the carbon material by removing the metal ultrafine particles adhering to the carbon material by heating or an external force, according to any one of claims 1 to 7. Manufacturing method of carbon composite material.