JP4866982B2 - Method for breaking carbon nanotube and carbon nanotube - Google Patents

Description

The present invention relates to a carbon nanotube breaking method and a carbon nanotube.

As a method for breaking and cutting carbon nanotubes, one disclosed in Japanese Patent Application Laid-Open No. 2004-43258 is known. The cutting method disclosed in this publication is characterized in that the carbon nanotubes are cut by crushing the mixed solution in which the carbon nanotubes are dispersed in the saccharide solution after heating and drying.
JP 2004-43258 A

According to the rupture method disclosed in the above publication, it is expected that the carbon nanotubes can be cut relatively easily. However, according to the examples, in order to cut the carbon nanotubes 1g, The work time in the ball mill alone takes a long time of 2 hours, the work efficiency is poor, and the carbon nanotubes have to be separated from the rod-shaped body after cutting, which requires many steps.
Therefore, an object of the present invention is to provide a carbon nanotube breaking method capable of easily and efficiently breaking carbon nanotubes, and a carbon nanotube broken by the method.

Said subject is achieved by the structure in any one of the following (1)-(7) of this invention.
(1) Cylindrical breaking device main body, a plurality of supply nozzles arranged at symmetrical positions around the central axis of the column at one end of the breaking device main body, and the other axial direction of the breaking device main body from each supply nozzle An inflow passage extending a predetermined length from there to the other end in the axial direction of the main body of the breaking device, and a carbon nanotube-supporting liquid to which pressure is applied from the inflow passage is introduced to break the carbon nanotube And an outflow passage having one end communicating with the breaking member and the other end opened to the other end of the breaking device, and the breaking member is formed of a hard material in close contact with each other to flow out the broken carbon nanotube. Circular first and second plate members that extend in the thickness direction of the first plate member and are smaller than the size of the inflow passage. An introductory passage is provided, and extends between the first and second plate members in the radial direction of the breaking device main body, and communicates the ends of the plurality of introducing passages on the breaking device main body side. A first processing passage that extends in a direction orthogonal to the first processing passage and a second processing passage that communicates with the first processing passage in the central portion, and a plate on the second plate member Breaking the carbon nanotubes using a carbon nanotube breaker provided with a plurality of outlet passages extending in the thickness direction, one end communicating with the end of the second processing passage and the other end communicating with the outflow passage. A method for breaking carbon nanotubes.
(2) When A is the pressure applied to the carbon nanotube-carrying liquid and B is the number of repetitions of rupture treatment through the carbon nanotube-carrying liquid through the carbon nanotube breaking device, A is 100 MPa or more, B is 10 or more, and A × The carbon nanotube breaking method according to the above (1), wherein the value of B is set to 1200 or more, and breaks into a state where 60% or more of carbon nanotubes having a length of 3 μm to 6 μm are contained.
(3) When A is the pressure applied to the carbon nanotube-carrying liquid and B is the number of repetitions of rupture treatment through the carbon nanotube-carrying device through the carbon nanotube crushing device, A is 100 MPa or more, B is 10 or more, and A × The carbon nanotube breaking method according to the above (1), wherein the value of B is 2600 or more, and the carbon nanotube having a length of 3 μm to 6 μm is broken into a state in which 80% or more is contained.
(4) The carbon nanotube breaking method according to any one of (1) to (3) above, wherein the concentration of carbon nanotubes in the carbon nanotube-supporting liquid is 0.001 to 30% by weight.
(5) The above-mentioned, which improves the dispersion effect by cutting and removing particles and carbon nanoparticles that are not formed into a tube shape even if they are amorphous or crystalline, which is a factor that impedes dispersion, The method for breaking carbon nanotubes according to any one of (1) to (4).
(6) The carbon nanotube breaking method according to any one of the above (1) to (4), wherein the length of the carbon nanotubes is made uniform to some extent to loosen the entanglement and improve dispersibility.
(7) The carbon nanotube breaking method according to any one of (1) to (4), wherein the length of the carbon nanotube broken by the diameter of the passage in the carbon nanotube breaking device is adjusted.

In the breaking method of the present invention, the carbon nanotubes can be easily and efficiently broken in a short time by using the breaking device having the above-described configuration and passing the pressurized carbon nanotube-supporting liquid.
In addition, both the ends of the carbon nanotubes were opened because the particles and carbon nanoparticles that were amorphous or crystalline but were not formed into a tube shape could be cut.
By opening both ends of the carbon nanotube, properties such as electron emission, hydrogen storage, and capacitance of the carbon nanotube are improved.
In addition, since the carbon nanotubes were cut to an appropriate substantially uniform length, the carbon nanotubes were easily dispersed evenly, and the dispersion efficiency when mixed with another substance was increased. Further, the carbon nanotubes having a substantially uniform length when attached to another substance exhibited a substantially uniform effect on the attached surface.

Hereinafter, a breaking device for carrying out a method for breaking a carbon nanotube according to an embodiment of the present invention will be described with reference to the accompanying drawings. Note that in this specification, the carbon nanotubes to be broken are in a form in which graphene having a pentagonal, hexagonal, heptagonal, or octagonal mesh is wound, and are single-walled or multi-layered with a thickness of 1 nm to several hundred nm And

Referring to FIGS described breaking apparatus. The breaking device 10 includes a columnar breaking device body 12, a plurality of supply nozzles 14 disposed at one end of the breaking device body 12 at symmetrical positions around the central axis of the cylinder, and the breaking devices from the supply nozzles 14. An inflow passage 16 extending for a predetermined length in the other axial direction of the main body 12 and extending again for a predetermined length in the other axial direction of the breaking device main body, and a carbon nanotube-supporting liquid from the inflow passage are introduced, and the carbon nanotube In order to flow out the broken carbon nanotubes, the breaker member 18 is broken, and an outflow passage 20 having one end communicating with the breaker member and the other end opened at the other end of the breaker main body is provided. As shown in FIG. 2 , the breaking member 18 includes circular first and second plate members 22 and 24 that are closely juxtaposed and formed of a hard material. The first plate member is provided with introduction passages 26 that extend in the thickness direction of the first plate member and that are smaller than the size of the inflow passage 16 and communicate with the inflow passage 16. Between the first and second plate members 22, 24, a first processing passage 28 that extends in the radial direction of the breaking device body 12 and communicates with the ends of the plurality of introduction passages 26 on the breaking device body side. And a second processing passage 30 extending in a direction orthogonal to the first processing passage 28 and communicating with the first processing passage in the center. The second plate member 24 is provided with a plurality of outlet passages 32 extending in the plate thickness direction, one end communicating with the end portion of the second processing passage 30 and the other end communicating with the outflow passage 20. Yes. The first and second processing passages 28 and 30 may have the same size, for example, a rectangular cross section having a width of 0.23 mm, a length of 1.8 mm, and a depth of 0.23 mm. The introduction passage 26 and the lead-out passage 32 may be the same size and have a circular cross section with a diameter of 2 mm.

In this example, the first processing passage 28 is formed by the groove 34 formed in the first plate member 22 shown in FIGS . 3 and 4 , and the second processing passage 30 is changed to the second plate shown in FIGS . 5 and 6. The grooves 36 are formed in the member 24. However, shallow cross-shaped grooves are formed on the mating surfaces of the first and second plate members, and these are combined to form a processing path. Any configuration may be used.

A carbon nanotube-supporting liquid supply source 60 is connected to the supply nozzle 14 of the apparatus 10 via a pressurizing device 50, and the carbon nanotube-supporting liquid from the carbon nanotube-supporting liquid supply source 60 is applied by the pressurizing device 50. The carbon nanotubes are broken by being supplied to the apparatus 10 in a pressed state. The carbon nanotube-supporting liquid supply source 60 may be connected to the outflow passage 20 of the apparatus main body 12. As a result, the carbon nanotube-carrying liquid treated by the apparatus 10 and having the carbon nanotubes broken can be automatically returned to the carbon nanotube-carrying liquid supply source 60. This facilitates repetition of the breaking process through the carbon nanotube supporting liquid through the carbon nanotube breaking device. By appropriately selecting the size of the processing path of the breaking member, the length of the carbon nanotube after breaking can be adjusted.

Next, a carbon nanotube breaking method using the carbon nanotube breaking device described above will be described.
First, a carbon nanotube supporting solution is prepared by suspending 0.001 to 30% by weight of carbon nanotubes in water or an organic solvent. If it is less than 0.001% by weight, the collision force between the carbon nanotube-carrying liquids is reduced, so that effective breakage cannot be achieved. If it exceeds 30%, the viscosity becomes too high and the collision force is not inferior. It is.

The prepared carbon nanotube-supporting liquid is preliminarily dispersed in an ultrasonic generator for about 10 minutes. This pre-dispersed carbon nanotube-carrying liquid is put into a carbon nanotube-carrying liquid supply source, and supply to the apparatus is started. The supplied carbon nanotube supporting solution is pressurized to 100 MPa or more, preferably 100 to 200 MPa by the pressurizing device 50. The carbon nanotube-carrying liquid flows into the breaking device 10 in a state of being pressurized in this way, and the carbon nanotubes are broken by passing through the processing passage and the like. This rupture process is performed by a repeated process in which the ruptured process is repeatedly supplied to the rupture device. The number of repetitions is 10 times or more, preferably 10 to 20 times.

It is preferable that the pressure of the carbon nanotube-supporting liquid and the number of repetitions of the rupture treatment have the following relationship. When the pressure (MPa) is A and the number of repetitions is B, the value of A × B is 1200 or more, preferably 2600 or more. When the value is 1200 or more, the carbon nanotube having a length of 3 μm to 6 μm can be broken into a state in which it is contained approximately 60% or more. Moreover, when it is 2600 or more, it becomes possible to break into a state in which approximately 80% of carbon nanotubes having a length of 3 μm to 6 μm are contained.

To demonstrate this, there are attached scanning photomicrographs and TG / DTA graphs. In this example, A is 140, B is 20, and therefore the value of A × B is 2800. In the scanning photomicrograph ( FIG. 7 ), most of the carbon nanotubes are entangled and aggregated before the treatment, the length varies from 3 μm to 20 μm, and one end thereof is closed. However, the treated carbon nanotubes ( FIG. 8 ) had a uniform length of about 3 μm to 6 μm. Particles and carbon nanoparticles that were amorphous or crystalline but not formed into a tube shape were broken, and carbon nanotubes with open ends were generated. Aggregation and entanglement before treatment were It is gone.

In addition, the TG / DTA graph shows that the combustion peak before the treatment ( FIG. 9 ) is 708.8 degrees after the treatment ( FIG. 10 ), compared to 808.8 degrees, and the combustion temperature is increased because the carbon nanotubes are broken. This is because it fell. In addition, the amorphous or crystalline particles that are not formed in a tube shape and the carbon nanoparticles are broken from the carbon nanotubes, and both ends are opened and the both ends are opened. It became exposed and became easy to burn at low temperatures. One sharp peak is formed at the temperature peak at which the carbon nanotubes burn both in the graph before and after the treatment. Since there are two or more peaks in the presence of impurities or damaged carbon nanotubes, this development has produced undamaged broken carbon nanotubes that have not lost the properties of carbon nanotubes. In the graph after the treatment, a clear combustion peak is observed at 293.4 degrees, and the weight is reduced by 4%. This peak is a particle or carbon nanoparticle that is amorphous or crystalline but is not formed into a tube shape and is broken from the carbon nanotube. This is because these substances are more combustible than the tube structure and burn at low temperatures. The low temperature peak is not seen in the graph before the treatment, but it is because the carbon nanotubes and amorphous or crystalline particles that are not formed into a tube and carbon nanoparticles are combined. It was because it was burned at the same temperature. Compared with before treatment, the TG graph after treatment shows a gentle curve toward the carbon nanotube combustion temperature. This is because short carbon nanotubes that are easy to burn at low temperatures are produced. By opening both ends of the carbon nanotube as described above, the properties of the carbon nanotube such as electron emission, hydrogen storage, and capacitance are improved.

In addition, since the carbon nanotubes were cut to an appropriate substantially uniform length, the carbon nanotubes were easily dispersed evenly, and the dispersion efficiency when mixed with another substance was increased. Further, the carbon nanotubes having a substantially uniform length when attached to another substance exhibited a substantially uniform effect on the attached surface. Dispersion effect could be improved by cutting and removing particles and carbon nanoparticles that are not formed into a tube shape even though they are amorphous or crystalline, which is a factor that hinders dispersion. . Furthermore, by making the length of the carbon nanotubes constant to some extent, it was possible to loosen the entanglement and improve the dispersibility.

As an analysis method, the above TG / DTA (differential heat, thermogravimetric measuring machine) and measurement using a scanning electron microscope were performed. The change in weight of the sample due to the increase (decrease) in ambient temperature is recorded with respect to time (temperature) as a TG curve, and the temperature difference between the reference and sample is detected by the electromotive force of the thermocouple installed in the sample holder This is a measurement method with a DTA curve and excellent quantitativeness. The treated carbon nanotubes were dried under reduced pressure and a sample was collected. In the scanning electron microscope, the processed sample was dried under reduced pressure, several points were photographed at random, and 100 carbon nanotubes were measured therefrom.

Examples of the present invention will be described below. In the following examples, an example using the carbon nanotube breaking apparatus shown in FIG. 1 and the like will be described.
First, a carbon nanotube supporting solution was prepared by suspending 0.1% by weight of carbon nanotubes in water to which a surfactant was added.
The prepared carbon nanotube-supporting liquid was predispersed in an ultrasonic generator over about 10 minutes. This pre-dispersed carbon nanotube-carrying liquid is put into a carbon nanotube-carrying liquid supply source, and supply to the apparatus is started. The supplied carbon nanotube supporting solution is flowed into the breaking device 10 while being pressurized by the pressurizing device 50, and the carbon nanotubes are broken by passing through the processing passage and the like. This rupture treatment was performed by a repeated treatment in which the ruptured treatment was repeatedly supplied to the breaking device.

Specifically, as shown in Table 1, the pressure and the number of repetitions are as follows. In Example 1, the pressure A is 100 MPa, the number of repetitions B is 12 times, and in Example 2, the pressure A is 120 MPa and the number of repetitions B In Example 3, the pressure A was 120 MPa, the number of repetitions B was 22 times, and in Example 4, the pressure A was 140 MPa and the number of repetitions B was 20 times.
The content of broken carbon nanotubes having a length of 3 to 6 μm was examined and shown in Table 1.

この表から本発明の効果が明らかである。

The effect of the present invention is clear from this table.

It is a schematic diagram which shows the structure of the carbon nanotube fracture | rupture apparatus by the 1st form of this invention. It is a cross-sectional view of a main part of the breaking apparatus shown in FIG. It is a front view of a first plate member of the main part shown in FIG. It is a longitudinal sectional view of the first plate member shown in FIG. It is a front view of a main portion of the second plate member shown in FIG. It is a longitudinal sectional view of the second plate member shown in FIG. It is a scanning micrograph of the carbon nanotube before a fracture | rupture process. It is a scanning micrograph of the carbon nanotube after a fracture | rupture process. It is a figure which shows the TG / DTA graph of the carbon nanotube before a fracture | rupture process. It is a figure which shows the TG / DTA graph of the carbon nanotube after a fracture | rupture process.

DESCRIPTION OF SYMBOLS 10 Carbon nanotube breaking device 12 Breaking device main body 14 Supply nozzle 16 Inflow passage 18 Breaking member 20 Outflow passage 22 First plate member 24 Second plate member 26 Introduction passage 28 First processing passage 30 Second processing passage 32 Outlet passage 34 Groove 36 Groove 50 Pressurizing device 60 Carbon nanotube-supporting liquid supply source

Claims (7)

A cylindrical breaking device body, a plurality of supply nozzles arranged at symmetrical positions around the central axis of the cylinder at one end of the breaking device body, a predetermined length from each supply nozzle in the other axial direction of the breaking device body An inflow passage extending from the inflow passage to the other end in the axial direction of the breaking device main body, a carbon nanotube-supporting liquid to which pressure is applied from the inflow passage, and a breaking member for breaking the carbon nanotube, In order to allow the carbon nanotubes to flow out, a circular shape formed of a hard material having an outflow passage having one end communicating with the breaking member and the other end opened at the other end of the breaking device, and the breaking members are closely juxtaposed. The first plate member extends in the thickness direction of the first plate member, is smaller than the size of the inflow passage, and is connected to the inflow passage. An introduction passage extending between the first plate member and the second plate member in the radial direction of the breaking device main body, and communicating with end portions of the plurality of introduction passages on the breaking device main body side. One processing path and a second processing path extending in a direction orthogonal to the first processing path and communicating with the first processing path are formed in the center, and the second plate member has a thickness direction The carbon nanotubes are broken using a carbon nanotube breaking device provided with a plurality of outlet passages having one end communicating with the end of the second processing passage and the other end communicating with the outflow passage. To break carbon nanotubes. When the pressure applied to the carbon nanotube-carrying liquid is A and the number of repetitions of the breaking process through the carbon nanotube-carrying liquid through the carbon nanotube breaking device is B, A is 100 MPa or more, B is 10 or more, and A × B The method for breaking carbon nanotubes according to claim 1, wherein the breaking method is such that the carbon nanotubes having a length of 3 to 6 µm are contained in an amount of 60% or more. When the pressure applied to the carbon nanotube-carrying liquid is A and the number of repetitions of the breaking process through the carbon nanotube-carrying liquid through the carbon nanotube breaking device is B, A is 100 MPa or more, B is 10 or more, and A × B The method of breaking carbon nanotubes according to claim 1, wherein the breaking method is such that the carbon nanotubes having a length of 3 to 6 µm are contained in an amount of 80% or more. The carbon nanotube breaking method according to any one of claims 1 to 3, wherein the concentration of carbon nanotubes in the carbon nanotube-supporting liquid is 0.001 to 30% by weight. The dispersion effect is improved by cutting and removing particles and carbon nanoparticles that are not formed into a tube shape even if they are amorphous or crystalline, which is a factor that hinders dispersion, which the carbon nanotube has. 4. The method for breaking carbon nanotubes according to any one of 4 above. The method for breaking carbon nanotubes according to any one of claims 1 to 4, wherein the length of the carbon nanotubes is made uniform to some extent to loosen the entanglement and improve dispersibility. The method for breaking carbon nanotubes according to any one of claims 1 to 4, wherein the length of the broken carbon nanotubes is adjusted according to the diameter of the passage in the carbon nanotube breaking device.

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