KR20160054985A - Method for preparing carbon nanotube-metal complex - Google Patents

Abstract

The present invention relates to a preparation method of a carbon nanotube-metal composite, the carbon nanotube-metal composite prepared according to the preparation method, and a magnetic wave shielding material or a conductive polymer comprising the carbon nanotube-metal composite. More particularly, the preparation method of a carbon nanotube-metal composite comprises: a) a mixing step of mixing a composition including carbon nanotube, distilled water as a first solvent, a second solvent, and metal nitrate; b) a drying step of evaporating the distilled water and the second solvent in the composition; c) an oxidation step of converting nitric acid of the metal nitride in the composition into nitrogen oxide, and converting metal into metal oxide; and d) a reduction step of reducing the metal oxide into metal. The preparation method of the present invention can prepare a carbon nanotube-metal composite in a large quantity while generating little amount of industrial wastewater.

Description

METHOD FOR PREPARING CARBON NANOTUBE-METAL COMPLEX [0002]

The present invention relates to a method for producing a carbon nanotube-metal composite and a carbon nanotube-metal composite produced thereby.

Electroless plating and electroplating are widely known as a method of plating metal on the surface of carbon nanotubes. Since the electroless plating is subjected to a pretreatment process using tin and palladium, the process becomes complicated, the production cost rises, and industrial waste water is generated. Electroplating is a method of plating using electricity, which is not possible with non-conductive materials, and industrial waste water is generated. In addition, electrolytic plating has a disadvantage in that it is difficult to double coat the carbon nanotubes with a metal.

Korean Patent Laid-Open Publication No. 2003-0019527 (Mar. 2003.)

The present invention relates to a process for attaching at least one metal particle to a surface of a carbon nanotube or dispersing it between carbon nanotubes using metal nitrate, and to provide a process capable of mass production and scarcely producing industrial wastewater. The present invention also provides a method for producing a composite of a carbon nanotube and a metal, which can minimize the possibility of exposure of a harmful substance to a person involved in manufacturing

The present invention provides a method for producing a carbon nanotube, comprising: a) mixing a composition comprising carbon nanotubes, distilled water as a first solvent, a second solvent and a metal nitrate salt; b) a drying step of evaporating the distilled water and the second solvent in the composition; c) an oxidation step of converting nitric acid to nitrogen oxide in the metal nitrate salt of the composition and converting the metal to a metal oxide; And d) a reduction step of reducing the metal oxide to a metal. The present invention also provides a method for producing a carbon nanotube-metal composite.

The present invention provides a carbon nanotube-metal composite produced by the method for producing the carbon nanotube-metal composite.

The present invention provides an electromagnetic shielding material comprising the carbon nanotube-metal composite.

The present invention provides a conductive polymer comprising the carbon nanotube-metal composite.

The present invention can attach a metal to the surface of carbon nanotubes or disperse metal particles between carbon nanotubes by a simple process. Accordingly, the carbon nanotube-metal composite produced by the method of the present invention has a high density of carbon nanotubes and improved physical properties such as thermal conductivity and electrical conductivity. In addition, the carbon nanotube-metal composite produced by the method of the present invention can be used as an electromagnetic wave shielding material or a conductive polymer depending on the type of metal attached to the carbon nanotube.

FIG. 1 illustrates processes of a method of manufacturing a carbon nanotube-metal composite according to an embodiment of the present invention.
FIG. 2 is a photograph of a SEM according to the content of nickel in the carbon nanotube-metal composite according to an embodiment of the present invention.
FIG. 3 is a photograph of SEM and EDS according to the content of nickel in the carbon nanotube-metal composite according to an embodiment of the present invention.
FIG. 4 is a photograph of a TEM photograph of a carbon nanotube-metal composite according to an embodiment of the present invention.

In the present specification, the term "carbon nanotube" (CNT) refers to a carbon isotope, which is a material having a cylindrical or spiral structure in which a carbon atom forms sp ² bonds with other carbon atoms around the carbon atom.

Hereinafter, a method for producing a carbon nanotube-metal composite according to the present invention will be described in detail.

Preparation of Carbon Nanotubes

In one embodiment of the present invention, the carbon nanotube may be a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (SWCNT), or a multi-walled carbon nanotube (multi -walled carbon nanotube, MWCNT).

The carbon nanotube may be a functionalized carbon nanotube that has been chemically activated on the surface of the carbon nanotube.

The carbon nanotubes may be treated to increase the purity of carbon nanotubes, that is, purified carbon nanotubes.

In one embodiment of the present invention, the method further comprises the step of functionalizing the carbon nanotubes of the composition prior to the mixing step.

The step of functionalizing the carbon nanotubes of the composition further comprises adding a mixed solution of sulfuric acid and nitric acid. When a mixed solution of sulfuric acid and nitric acid is added and the carbon nanotubes are washed, a carboxyl group may be added to the carbon nanotubes to function.

The volume ratio of sulfuric acid: nitric acid in the mixed solution may be 3: 1.

In one embodiment of the present invention,

The step of purifying the carbon nanotubes of the composition may include washing the carbon nanotubes with distilled water. The washing with the distilled water may be performed at least once, and unnecessary metal catalyst, amorphous carbon, and the like are removed from the carbon nanotubes during the washing process.

In one embodiment of the present invention, the step of purifying the carbon nanotubes of the composition further comprises adding a nitric acid solution. The step of adding the nitric acid solution may remove an impurity or a metal catalyst remaining in the carbon nanotube after the nitric acid solution is added.

The concentration of the nitric acid solution may be 0.5 mol% or more and 2.0 mol% or less. If the concentration of the nitric acid solution is 0.5 mol% or less, impurities or metal catalyst remaining in the carbon nanotubes can not be removed. If the concentration of the nitric acid solution is 2.0 mol% or more, defects due to acid may occur on the surface of the carbon nanotubes.

In one embodiment of the present invention, the step of functionalizing the carbon nanotubes of the composition and the step of purifying the carbon nanotubes of the composition are carried out simultaneously.

Mixing step of carbon nanotube-containing composition

In one embodiment of the present invention, the mixing step may use a mixer, and the mixer may be a planetary mixer, a homogenizer, or the like.

In one embodiment of the present invention, the metal nitrate of the composition is a nitrate of any one or two or more metals selected from the group consisting of nickel, iron and cobalt. The metal nitrate of the composition may be a nitrate of silver, sodium, magnesium, calcium, copper, lead or zinc, but the nitrate of the composition may be nitrate of any one or two or more metals selected from the group consisting of nickel, iron and cobalt Nickel, iron and cobalt are preferred because they are ferromagnetic materials. In particular, nickel-iron, iron-cobalt, or nickel-iron-cobalt alloys are more preferable because of their excellent effect of shielding the electric wave.

In one embodiment of the present invention, the metal nitrate of the composition is a nitrate of any one or two or more metals selected from the group consisting of nickel, iron and cobalt.

In one embodiment of the present invention, the second solvent of the composition is any one or two or more selected from the group consisting of ethanol, acetone, methanol, propanol and butanol.

The second solvent of the composition is preferably water-soluble and well mixed with distilled water, and it is preferable that after the evaporation, no residue due to the second solvent remains on the surface of the carbon nanotube.

In one embodiment of the present invention, the volume ratio of the distilled water to the second solvent of the composition is 5: 1 or more and less than 1: 0.

When the volume ratio of the distilled water and the second solvent is 1: 0, that is, when only distilled water is used, the evaporation rate of the solvent is slowed. When the ratio is 5: 1 or less, the evaporation rate of the solvent is increased, Since the metal can not evaporate due to its relatively large mass and melting point, it accumulates on the carbon nanotubes, resulting in a separation of the carbon nanotubes and the metal.

In one embodiment of the present invention, the weight ratio of the carbon nanotubes of the composition to the first solvent, the second solvent, and the metal nitrate is 1:10 or more and 1:20 or less. When the weight ratio is 1:10 or more, the size of the metal attached to the surface of the carbon nanotubes is increased, the dispersibility and uniformity of the metal are decreased, and when the weight ratio is 1:20 or less, A phase separation phenomenon between the solvent and the carbon nanotube appears, which is not preferable.

In one embodiment of the present invention, the second solvent of the composition has a boiling point of 50 ° C or higher and 100 ° C or lower.

In one embodiment of the present invention, the mixing step further comprises mixing the composition using one or more selected from the group consisting of an ultrasonic mixer, a planetary mixer, and a shear mixer.

Pelletizing the carbon nanotube-containing composition

In one embodiment of the present invention, the method further comprises a pelletizing step of heating the composition in the mixing step.

When the pelletization step is not carried out, the final material forms a bundle of various sizes from the powder form. This means that there is a strong possibility that the forces applied at the matrix and mixing stage during fabrication of the composite material are unbalanced. Thus, producing pellets of uniform size through the pelletizing step has the advantage of uniformly transferring the force in mixing with the matrix.

In one embodiment of the present invention, the pelleting step is carried out for a period of not less than 24 hours but not longer than 36 hours.

In one embodiment of the present invention, the pelleting step is conducted at a temperature of 100 ° C or higher and 200 ° C or lower.

The step of drying the carbon nanotube-containing composition

In one embodiment of the present invention, the drying step is performed for 24 hours or more and 48 hours or less. If the drying step is less than 24 hours, the drying is not completed. If the drying step is performed for more than 48 hours, nitrogen oxides are generated in the air.

The drying time may vary depending on the composition of the composition. Specifically, an increase in the amount of distilled water can increase the drying time.

In one embodiment of the present invention, the drying step is conducted at a temperature of 100 ° C or higher and 200 ° C or lower.

Oxidation step of carbon nanotube-containing composition

In the oxidation step of the present invention, when a metal catalyst such as iron, magnesium, or nickel is present in the carbon nanotube, the metal catalyst inside the carbon nanotube may be removed. If amorphous carbon exists in the carbon nanotube, Can be removed.

In one embodiment of the present invention, the oxidation step is carried out at a temperature of 350 ° C or higher but not higher than 450 ° C. If the temperature of the oxidation step is lower than 350 ° C., the metal oxide may not be completely formed, unnecessary catalyst, and carbon may be left. If the temperature is lower than 450 ° C., carbon nanotubes may be carbonized.

In one embodiment of the present invention, the oxidizing step further comprises supplying an inert gas.

The inert gas includes a gas that does not participate in the reaction when the metal nitrate attached to the carbon nanotube reacts at the reaction temperature of the oxidation step.

In one embodiment of the present invention, the inert gas is any one or two or more selected from the group consisting of argon, helium, nitrogen, neon, krypton, xenon and radon. Such an inert gas can transmit heat without reacting with the metal and the carbon nanotube, and can transfer the nitrogen oxide gas generated in the oxidation step and the like.

In one embodiment of the present invention, the oxidation step uses thermal chemical vapor deposition.

In one embodiment of the present invention, the oxidizing step applies energy such as light, heat, and electromagnetic waves from the outside.

In one embodiment of the present invention, the method further comprises the additional step of forming a non-oxidizing atmosphere.

Reduction step of the carbon nanotube-containing composition

In one embodiment of the present invention, the reducing step is conducted at a temperature of 550 ° C or higher and 650 ° C or lower. The reduction does not proceed at a temperature lower than 550 deg. C, and carbonization of the carbon nanotube occurs at a temperature higher than 650 deg. C, which is not preferable.

In one embodiment of the present invention, the reducing step further comprises supplying gas.

The gas is preferably a gas having hydrogen, and more specifically, one or two or more gases selected from the group consisting of hydrogen, ethylene and ammonia are preferable, and hydrogen gas having the best reactivity is particularly preferable.

In one embodiment of the present invention, the oxidation step uses thermal vapor chemical vapor deposition.

In one embodiment of the present invention, the oxidizing step applies energy such as light, heat, and electromagnetic waves from the outside.

In one embodiment of the present invention, the method further comprises the additional step of forming a non-oxidizing atmosphere.

The cooling step of the carbon nanotube-containing composition

In one embodiment of the present invention, the method further comprises cooling the composition until it is at room temperature after the reducing step.

The cooling step prevents the metal particles from being oxidized in the carbon nanotube-metal composite.

Hereinafter, the carbon nanotube-metal composite according to the present invention and the carbon nanotube-metal composite will be described in detail.

The present invention provides a carbon nanotube-metal composite produced by the method for producing the carbon nanotube-metal composite. The carbon nanotube-metal composite prepared by electroless plating has tin or palladium as a medium between the carbon nanotubes and the metal, whereas the carbon nanotube-metal composite according to the present invention does not have a medium between the carbon nanotubes and the metal Do not.

The description of the carbon nanotube-metal composite described above applies to the method of manufacturing the carbon nanotube-metal composite unless otherwise specified.

The present invention provides an electromagnetic shielding material comprising the carbon nanotube-metal composite. The carbon nanotube-metal composite of the present invention is a filling material coated with a ferromagnetic metal on a carbon nanotube, and thus has excellent electromagnetic wave shielding efficiency when dispersed in a polymer.

The present invention provides a conductive polymer comprising the carbon nanotube-metal composite. The carbon nanotube-metal composite of the present invention is a filler material coated with a ferromagnetic metal on a carbon nanotube, and thus the electrical conductivity increases when dispersed in a polymer.

Hereinafter, the configuration and effects of the present invention will be described in more detail with reference to examples. However, these examples are provided for illustrative purposes only in order to facilitate understanding of the present invention, and the scope and scope of the present invention are not limited by the following examples.

[Example 1] Production of carbon nanotubes

Carbon nanotube-metal complexes were prepared by performing the steps as shown in Table 1 below.

Implementation contents Mixing step Types of Carbon Nanotubes Multi-Walled Carbon Nanotubes Type of the second solvent ethanol Types of metals nickel Types of nitrates Nickel metal salt Mixed component On the surface of the carbon nanotubes, 20 mass% nickel coating standard
15 g of carbon nanotubes, 200 g of distilled water, 100 g of ethanol, 18.5 g of nickel metal salt Type of mixer, its name and manufacturer Double-planetary Kneader Mixer, T.K. HIVIS MIX 2P-03/1, PRIMIX Co. Pelletization step After the mixing step, after 3 to 6 hours at 100 to 200 ° C, pelletization is carried out using a pelletizer Drying step Drying temperature 150 ℃ Drying time 24 hours Oxidation step Oxidation temperature 400 ° C Oxidation time 1 hours Inert gas type, its concentration and supply time Argon gas, 1 hour, 3 L / min Using thermal vapor deposition equipment Reduction step Oxidation temperature 600 ℃ Oxidation time 1 hours Oxidizer gas type, its concentration and supply time Hydrogen, 1 hour, 3 L / min Inert gas type, its concentration and supply time Argon, 1 hour, 1 L / min Used device Thermal vapor deposition apparatus Cooling step Cooling temperature Room temperature

Further, in the mixing step of the embodiment, the 20 mass% nickel coating standard was changed to 33.3 mass%, 50 mass%, 60 mass% and 66.7 mass% on the surface of the carbon nanotubes, respectively, 25 phr, 50 phr, 100 phr, 150 phr and 200 phr to prepare a carbon nanotube-metal composite.

The obtained carbon nanotube-metal composite and the untreated carbon nanotube were photographed respectively in FIG. 2 to FIG. 4, and the photographing equipment and conditions are shown in Table 2 below.

Photographic equipment Specific implementation details SEM
(scanning electron microscope) Product name and manufacturer S-4800, HITACHI Co. Shooting conditions 15.0 kV, 20,000 times EDS
(Energy-dispersive X-ray spectroscopy) Product name and manufacturer EX-250, HORIBA Shooting conditions 12.0 kV, 20,000 times TEM
(Transmission electron microscopy) Product name and manufacturer H7600, HITACHI Co. Shooting conditions 200.0 kV, 200,000 times

Claims (16)

a) mixing a composition comprising carbon nanotubes, distilled water as a first solvent, a second solvent and a metal nitrate;
b) a drying step of evaporating the distilled water and the second solvent in the composition;
c) an oxidation step of converting nitric acid to nitrogen oxide in the metal nitrate salt of the composition and converting the metal to a metal oxide; And
and d) a reduction step of reducing the metal oxide to a metal. The method of claim 1, wherein the metal nitrate of the composition is a nitrate of one or more metals selected from the group consisting of nickel, iron and cobalt. The method for producing a carbon nanotube-metal composite according to claim 1, wherein the metal nitrate of the composition is a nitrate of any one or two or more metals selected from the group consisting of nickel, iron and cobalt nitrate. The method of claim 1, wherein the volume ratio of the distilled water to the second solvent in the composition is 5: 1 or more and less than 1: 0. The method of claim 1, wherein the weight ratio of the carbon nanotubes to the first solvent, the second solvent, and the metal nitrate is 1:10 or more and 1:20 or less. The method for producing a carbon nanotube-metal composite according to claim 1, wherein the second solvent of the composition has a breaking point of 50 ° C or higher and 100 ° C or lower. 6. The method of claim 5, wherein the second solvent of the composition is one or more selected from the group consisting of ethanol, acetone, methanol, propanol, and butanol. The method of claim 1, wherein the drying step is performed at a temperature of 100 ° C or higher and 200 ° C or lower. The method of claim 1, wherein the oxidation step is performed at a temperature of 50 ° C or more and 100 ° C or less. The method of claim 1, wherein the oxidizing step further comprises supplying at least one gas selected from the group consisting of argon, helium, nitrogen, neon, krypton, xenon and radon. Metal complex. The method of claim 1, wherein the reducing step is performed at a temperature of 350 ° C or higher and 450 ° C or lower. 2. The method of claim 1, wherein the reducing step further comprises supplying at least one gas selected from the group consisting of hydrogen, ethylene, and ammonia. The method of claim 1, further comprising cooling the composition until room temperature is reached after the reducing step. 14. A carbon nanotube-metal composite produced by the method of any one of claims 1 to 13. An electromagnetic wave shielding material comprising the carbon nanotube-metal composite according to claim 14. 14. A conductive polymer comprising the carbon nanotube-metal composite of claim 14.

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