JP4812381B2 - Method for producing metal-based carbon nanotube composite material - Google Patents

Description

The present invention relates to a method of manufacturing a metal-based carbon nanotube composite materials, more particularly, the metal base carbon nanotube composite material prepared by uniformly dispersing the carbon nanotubes in the metal matrix, in particular containing sodium dodecyl sulfate, or the residue a method of manufacturing a non metal based carbon nanotube composite materials.

  Up to now, no method has been developed for producing a metal / carbon nanotube composite material in which carbon nanotubes can be uniformly dispersed in a metal matrix, and the low density, high strength, high thermal conductivity of carbon nanotubes or Metal / carbon nanotube composites that take advantage of excellent properties such as high elastic modulus have not been obtained.

  On the other hand, the present inventors prepared a metal slurry using metal powder as one of the methods for producing a metal-based carbon nanotube composite material in a patent application (Japanese Patent Application No. 2005-088697) dated March 25, 2005. A step of producing a carbon nanotube suspension using carbon nanotubes, a step of producing a mixed slurry of metal / carbon nanotubes using the obtained metal slurry and carbon nanotube suspension, and the obtained metal / carbon A metal base comprising: a step of producing a metal / carbon nanotube mixed green molded body using a nanotube mixed slurry; and a step of firing the obtained metal / carbon nanotube mixed green molded body to obtain a metal-based carbon nanotube composite material Carbon nanotube composite Manufacturing method, and metal-based carbon nanotube composite material obtained thereby, carbon nanotubes are uniformly dispersed in the carbon nanotube suspension, and further, carbon nanotubes are uniformly dispersed in the metal-based carbon nanotube composite material. For the purpose of the above, a dispersant is used, and general sodium dodecyl sulfate is used as the dispersant.

Thus, by producing by the above-described method, it becomes possible to uniformly disperse the carbon nanotubes in the metal-based carbon nanotube composite material. It is difficult to completely degrease sodium dodecyl sulfate or its residue used as an agent, and there is a high possibility that it will remain.
And there existed room for improvement that the heat conductivity and mechanical strength characteristic which a metal group carbon nanotube composite material exhibits are not fully utilized by sodium dodecyl sulfate or its residue existing.

The present invention has been made in view of such problems of the prior art, and the object of the present invention is to uniformly disperse carbon nanotubes in the metal-based carbon nanotube composite material, and to add sodium dodecyl sulfate or its It is to provide a method for producing free residue metal based carbon nanotube composite materials.

As a result of intensive studies to achieve the above object, the present inventors have produced a metal slurry using metal powder, produced a carbon nanotube suspension using carbon nanotubes, and obtained metal slurry and carbon nanotubes. A metal / carbon nanotube mixed slurry is prepared using the suspension, a metal / carbon nanotube mixed green molded body is manufactured using the obtained metal / carbon nanotube mixed slurry, and the obtained metal / carbon nanotube mixed green molding is obtained. In producing a metal-based carbon nanotube composite material by firing a body, a metal slurry is produced using a metal powder, and nickel and / or aluminum powder having an average particle size of 0.1 to 50 μm is used as the metal powder. Make nanotube suspension In doing so, it was found that the above-mentioned object can be achieved by using polyvinyl alcohol as a dispersant for carbon nanotubes and adding the polyvinyl alcohol in a weight ratio of 4 times or more the amount of carbon nanotubes, thereby completing the present invention. It was.

That is , the method for producing a metal-based carbon nanotube composite material of the present invention includes a step (1) of producing a metal slurry using a metal powder, a step (2) of producing a carbon nanotube suspension using a carbon nanotube, Using the metal slurry obtained in the step (1) and the carbon nanotube suspension obtained in the step (2), a step (3) for producing a metal / carbon nanotube mixed slurry and the step (3) obtained. Step (4) of producing a metal / carbon nanotube mixed green molded body using the obtained metal / carbon nanotube mixed slurry, and firing the metal / carbon nanotube mixed green molded body obtained in the step (4) to form a metal And (5) obtaining a carbon-based carbon nanotube composite material. A method of manufacturing a material, polyvinyl in the step (1), using a nickel and / or aluminum powder having an average particle size of 0.1~50μm as metal powder in the step (2), as a dispersant for carbon nanotubes An alcohol is used, and the polyvinyl alcohol is added at a weight ratio of 4 times or more of the carbon nanotubes.

According to the present invention, a metal slurry is produced using metal powder, a carbon nanotube suspension is produced using carbon nanotubes, and a metal / carbon nanotube mixed slurry is produced using the obtained metal slurry and carbon nanotube suspension. A metal / carbon nanotube mixed green molded body is prepared using the metal / carbon nanotube mixed slurry obtained, and the obtained metal / carbon nanotube mixed green molded body is fired to obtain a metal-based carbon nanotube composite material. strikes, in making the metal slurry with a metal powder, using a nickel and / or aluminum powder having an average particle size of 0.1~50μm as metal powder, in making the carbon nanotube suspension, for a carbon nanotube dispersant Then, using polyvinyl alcohol and adding the polyvinyl alcohol in a weight ratio of 4 times or more of the carbon nanotubes, the carbon nanotubes are uniformly dispersed in the metal-based carbon nanotube composite material, and sodium dodecyl sulfate or its the residue method for producing a metal-based carbon nanotube composite materials containing no can be provided.

Contact name herein, "CNT" Carbon nanotubes, polyvinyl alcohol "PVA", sodium dodecyl sulfate, "SDS", aluminum "Al", may be described nickel as "Ni".

Moreover , as said metal powder and the dispersion medium for CNTs, an aqueous thing and a non-aqueous thing can be used, for example.
Typical examples of the water-based material include pure water and water containing an alloy element that is appropriately added as necessary.
“Pure water” means (1) water that exhibits an electric resistance value exceeding that of distilled water, and (2) water from which ions have been completely removed.
Moreover, as said non-aqueous thing, the organic solvent represented by lower alcohols, such as methanol, ethanol, a propyl alcohol, can be mentioned, for example.

The manufacturing method of the metal group CNT composite material of this invention is demonstrated in detail.
As described above, the method for producing a metal-based CNT composite material according to the present invention includes a step (1) of producing a metal slurry using metal powder, a step (2) of producing a CNT suspension using CNT, and the step. Using the metal slurry obtained in (1) and the CNT suspension obtained in the above step (2), a step (3) for producing a metal / CNT mixed slurry, and the metal obtained in the step (3) Step (4) for producing metal / CNT mixed green molded body using / CNT mixed slurry, and firing metal / CNT mixed green molded body obtained in step (4) to obtain metal-based CNT composite material and step (5) a method for producing a metal-based CNT composite material comprising, in the step (1), any one of nickel powder and aluminum powder having an average particle diameter of 0.1~50μm metal powder With square or both, in the step (2), using PVA as CNT dispersant is added 4 times or more of the CNT to the PVA in a weight ratio, is a method of obtaining a desired metal base CNT composite .
More specifically, the metal slurry and the CNT suspension are prepared in separate steps by passing through such steps, and then mixed together to obtain an average particle size of 0.1 to 0.1 particularly as a metal powder. In one or both of 50 μm nickel powder and aluminum powder, using PVA as a dispersant for CNT, and adding the PVA in a weight ratio of 4 times or more of CNT, in the metal-based CNT composite material CNTs are uniformly dispersed and do not contain SDS or its residue.

In the method for producing a metal-based CNT composite material according to the present invention, in the step (5), it is desirable that the metal / CNT mixed green molded body is held and fired at 550 to 660 ° C. for 1 hour or longer in an Ar atmosphere.
By going through such a process, the CNTs are more uniformly dispersed in the metal-based CNT composite material and do not contain SDS or its residue.
When firing, a pressure of about 50 to 200 MPa may be applied.

Furthermore, in the method for producing a metal-based CNT composite material according to the present invention, it is desirable to add a degreasing step (4 ′) between the steps (4) and (5).
In the step (4 ′), it is more preferable that the degreasing treatment is carried out in the atmosphere at 400 to 600 ° C. for 10 to 20 hours, but is not limited thereto.
By passing through such a process, PVA used as a CNT dispersant can be sufficiently degreased before firing, and CNT is more uniformly dispersed in the metal-based CNT composite material, and contains SDS or its residue. It will not do.

Moreover, it is preferable to perform the manufacturing method of the metal group CNT composite material of this invention in the said (4) process under the pressurization conditions of 200 Mpa in air | atmosphere.
By passing through such a process, it has sufficient relative density, CNT disperses | distributes more uniformly in the said metal group CNT composite material, and it does not contain SDS or its residue.

Furthermore, the metal-based CNT composite material production method of the present invention is preferably obtained by performing ultrasonic treatment and stirring and mixing treatment simultaneously for at least 1 hour in the step (2).
Through such a process, CNTs can be more uniformly dispersed in the CNT suspension, and CNTs are more evenly dispersed in the metal-based CNT composite material, and no SDS or residue thereof is contained. .

Moreover, it is preferable that the average outer diameter of CNT used in the said (2) process is 15-100 nm in the manufacturing method of the metal group CNT composite material of this invention.
CNT has an average outer diameter exceeding 100 nm because its physical properties increase the number per unit amount as the average outer diameter is smaller, and the length of the CNT in the axial direction is longer and high thermal conductivity is obtained. This is because it is not suitable as CNT blended for imparting high thermal conductivity.
On the other hand, CNTs having an average outer diameter of 15 nm or more have excellent handling properties, and when produced using such CNTs, CNTs can be more uniformly dispersed in the metal-based CNT composite material. Although it is easy to disperse | distribute without forming an aggregate, it is not necessarily limited to this.

Furthermore, the method for producing a metal-based CNT composite material of the present invention includes that the metal powder used in the step (1) is one or both of nickel powder and aluminum powder having an average particle size of 0.1 to 10 μm. It is preferable .

When the average particle size is less than 0.1 μm, the raw material cost increases, and in the case of a metal that easily oxidizes such as aluminum, handling may be difficult, which is not preferable.
On the other hand, if the average particle size exceeds 50 μm, CNT aggregates in the gaps between the particles, so that the dispersibility of CNT tends to deteriorate, which is not preferable.

  Such metal-based CNT composite material can more uniformly disperse the metal powder in the metal slurry, and therefore, CNT is more uniformly dispersed in the metal-based CNT composite material and contains SDS or its residue. However, the present invention is not necessarily limited to this.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

(Example 1)
FIG. 1 is a flowchart showing an example of a method for producing a metal-based CNT composite material of the present invention. Example 1 will be described with reference to FIG.

<Production of CNT suspension>
In Example 1, as shown in the figure, in order to produce a CNT suspension, multilayer CNTs having an average outer diameter of 50 nm as a raw material powder, polyvinyl alcohol as a dispersant (Wako Pure Chemical Industries, Ltd., polymerization degree 500) Pure water was prepared as a solvent.
To 100 parts by weight of pure water, 0.8 parts by weight of polyvinyl alcohol and 0.2 parts by weight of multi-walled CNTs were sequentially added, and then sonication and stirring and mixing were simultaneously performed to obtain a CNT suspension. .

  The ultrasonic treatment was performed at an output of 7 W for 1 hour, and stirring and mixing were performed at a rotation speed of 200 rpm. Further, the ultrasonic treatment and stirring and mixing described below were performed under the same conditions.

<Preparation of metal slurry>
On the other hand, in order to prepare a metal slurry, among them, Al powder (Toyo Aluminum Co., Ltd. 04-0011) having an average particle diameter of 3 μm was prepared as a raw material powder, and ethanol was prepared as a solvent.
Al powder was added to ethanol, and then ultrasonic treatment and stirring and mixing were simultaneously performed to obtain an Al slurry.

<Preparation of metal / CNT mixed slurry>
Next, as shown in the figure, the CNT suspension and the Al slurry are mixed, subjected to ultrasonic treatment and stirring, and further heated to 80 ° C., not shown, and concentrated to obtain an Al / CNT mixed slurry. Produced.
Thereafter, the Al / CNT mixed slurry was allowed to stand at room temperature with stirring and concentrated.

<Preparation of metal / CNT mixed green compact>
Next, as shown in the figure, the concentrated Al / CNT mixed slurry is cast into a porous alumina mold, dried at room temperature at 20 ° C. for 24 hours, further vacuum dried for 6 hours, and then compressed at 200 MPa. Thus, an Al / CNT mixed green molded body was obtained.

<Production of metal-based CNT mixed green compact>
The Al / CNT mixed green molded body was heated to 400 ° C. in the atmosphere and then held for 20 hours to perform a degreasing treatment to obtain an Al-based CNT mixed green molded body (not shown).

<Production of metal-based CNT composite material>
The Al-based CNT composite green material of this example was obtained by hot pressing by holding the degreasing-treated Al-based CNT mixed green molded body in an Ar stream at 675 ° C. for 1 hour while applying a pressure of 100 MPa.
In the obtained Al-based CNT composite material, the CNT content was 5 vol%.

FIG. 2 is a scanning electron microscope (SEM) photograph of the Al-based CNT composite material of this example. In the figure, CNTs are indicated by arrows.
As shown in the figure, it can be seen that in the Al-based CNT composite material of this example, CNTs are dispersed in the Al matrix.

  Moreover, as a result of conducting the elemental analysis by energy dispersive X-ray fluorescence analysis (EDX) with respect to the Al group CNT composite material of this example, S and Na were not detected.

(Comparative Example 1)
In producing the CNT suspension, the same operation as in Example 1 was repeated except that polyvinyl alcohol used as the CNT dispersant was replaced with sodium dodecyl sulfate (Wako Pure Chemical Industries, 192-08672). An Al-based CNT composite material was obtained.
In addition, as a result of elemental analysis by EDX on the Al-based CNT composite material of this example, S and Na were detected.

( Reference Example 1 )
The CNT suspension produced in Example 1 was used.
Specifically, multilayer CNTs having an average outer diameter of 50 nm were prepared as a raw material powder, polyvinyl alcohol as a dispersant, and pure water as a solvent.
The CNT suspension of this example was prepared by sequentially adding 0.8 parts by weight of polyvinyl alcohol and 0.2 parts by weight of multi-walled CNT to 100 parts by weight of pure water, and then performing ultrasonic treatment and stirring and mixing simultaneously. Got.

FIG. 3 is an SEM photograph of the CNT suspension of this example. In the figure, CNT aggregates as observed in FIG. 4 of Reference Example 2 described later are not confirmed, and it can be seen that the CNTs are uniformly dispersed in the CNT suspension.
In addition, as a result of elemental analysis by EDX on the CNT suspension of this example, S and Na were not detected.

( Reference Example 2 )
The CNT suspension of this example is obtained by sequentially adding 0.2 parts by weight of polyvinyl alcohol and 0.2 parts by weight of multi-walled CNT to 100 parts by weight of pure water, and then simultaneously performing ultrasonic treatment and stirring and mixing. Got.

  FIG. 4 is an SEM photograph of the CNT suspension of this example. In the figure, as shown by the arrows, CNT aggregates were confirmed.

( Reference Example 3 )
A CNT suspension similar to Comparative Example 1 was used.
Specifically, multilayer CNTs having an average outer diameter of 50 nm were prepared as raw material powder, sodium dodecyl sulfate as a dispersant, and pure water as a solvent.
To 100 parts by weight of pure water, 0.5 parts by weight of sodium dodecyl sulfate and 2 parts by weight of multi-walled CNTs were sequentially added, and then sonication and stirring and mixing were simultaneously performed to prepare the CNT suspension of this example. Obtained.

FIG. 5 is an SEM photograph of the CNT suspension of this example. In the figure, CNT aggregates as observed in FIG. 4 of Reference Example 2 described above are not confirmed, and it can be seen that CNTs are uniformly dispersed in the CNT suspension.
However, as a result of elemental analysis by EDX on the CNT suspension of this example, S and Na were detected.

  From the above, it can be seen that a CNT suspension in which CNTs are uniformly dispersed can be produced by adding only polyvinyl alcohol as a CNT dispersant in an amount of 4 times the amount of CNTs by weight.

It is a flowchart which shows an example of the manufacturing method of the metal group CNT composite material of this invention. 2 is a SEM photograph of the Al-based CNT composite material of Example 1. 4 is a SEM photograph of the CNT suspension of Reference Example 1 . 4 is a SEM photograph of the CNT suspension of Reference Example 2 . 4 is a SEM photograph of a CNT suspension of Reference Example 3 .

Claims (7)

Producing a metal slurry using metal powder (1);
Producing a carbon nanotube suspension using carbon nanotubes (2);
Using the metal slurry obtained in the step (1) and the carbon nanotube suspension obtained in the step (2) to produce a metal / carbon nanotube mixed slurry (3);
Using the metal / carbon nanotube mixed slurry obtained in the step (3) to produce a metal / carbon nanotube mixed green molded body,
Firing the metal / carbon nanotube mixed green molded body obtained in the step (4) to obtain a metal-based carbon nanotube composite material (5), and a method for producing a metal-base carbon nanotube composite material,
In the step (1), nickel and / or aluminum powder having an average particle size of 0.1 to 50 μm is used as the metal powder,
In the said process (2), using polyvinyl alcohol as a dispersing agent for carbon nanotubes, this polyvinyl alcohol is added 4 times or more of carbon nanotubes by weight ratio, The manufacturing method of the metal group carbon nanotube composite material characterized by the above-mentioned. 2. The metal-based carbon nanotube composite material according to claim 1 , wherein in the step (5), the metal / carbon nanotube mixed green compact is fired by holding at 550 to 660 ° C. for 1 hour or more in an argon atmosphere. Production method. The method for producing a metal-based carbon nanotube composite material according to claim 1 or 2 , wherein a degreasing step (4 ') is added between the steps (4) and (5). 4. The method for producing a metal-based carbon nanotube composite material according to claim 3 , wherein in the step (4 ′), the degreasing treatment is performed by holding in the atmosphere at 400 to 600 ° C. for 10 to 20 hours. The method for producing a metal-based carbon nanotube composite material according to any one of claims 1 to 4, wherein the step (4) is performed under a pressurized condition of 200 MPa in the atmosphere. The method for producing a metal-based carbon nanotube composite material according to any one of claims 1 to 5, wherein in the step (2), the ultrasonic treatment and the stirring and mixing treatment are simultaneously performed for at least 1 hour. The method for producing a metal-based carbon nanotube composite material according to any one of claims 1 to 6, wherein an average outer diameter of the carbon nanotubes used in the step (2) is 15 to 100 nm.

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