KR101644676B1 - Metal particles of core-shell structure and method for manufacturing the same - Google Patents

Abstract

The present invention relates to metal particles having a core-shell structure and a method for producing the same. (1) obtaining a first metal solution comprising first metal particles; (2) obtaining a second metal coating liquid; (3) obtaining a reducing solution containing a reducing agent; And (4) repeating the step of alternately introducing a second metal coating solution and a reducing solution into the first metal solution, and a method of manufacturing a core-shell metal particle, Lt; / RTI > According to the present invention, the coating layer of the second metal constituting the shell is uniformly coated, and the coating amount is increased.

Description

TECHNICAL FIELD [0001] The present invention relates to a core-shell metal particle and a method of manufacturing the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a core-shell metal particle and a method of manufacturing the same. More particularly, the present invention relates to a core-shell metal particle having a core-shell structure in which a second metal (shell) Particles and a method for producing the same.

Metals such as silver (Ag) and copper (Cu) have excellent thermal and electrical properties. Among them, silver (Ag) has excellent electrical properties and antibacterial properties. Accordingly, silver (Ag) has been applied to electrode materials of various electronic products and antibacterial products. Particularly, silver (Ag) particles are produced in paste form and are usefully used as electrodes for display products and the like.

However, silver (Ag) is expensive and its strength is weak. In addition, metals such as copper (Cu) have a disadvantage of being weak in oxidation. Accordingly, metal particles having a core-shell structure complementary to the disadvantages of these metals have been attracting attention.

The metal particles having the core-shell structure as described above are mainly produced through electroplating, electroless plating and vapor phase reaction. However, methods such as electroplating and gas phase reaction are difficult to commercialize because of difficulty in coating with dense and uniform thickness. On the other hand, the electroless plating method enables a dense and uniform thickness coating. In addition, the electroless plating method is advantageous in that the manufacturing cost is low and mass production is possible from the industrial aspect. Most of the metal particles of the core-shell structure are manufactured by plating (coating) metal particles such as copper (Cu) as a core and a metal such as silver (Ag) as a shell have.

For example, Korean Patent Laid-Open Nos. 10-2004-0016097, 10-2007-0104802 and 10-2011-0059946 disclose a technique related to the above, (Ag) is coated on the surface of copper (Cu).

However, in the manufacturing method according to the related art, it is difficult for the coating layer such as silver (Ag) constituting the shell to be uniformly coated (plated). Further, there is a problem that the coating amount of silver (Ag) or the like is small. Particularly, when metal particles of a small size are used as the core, the degree of non-uniformity of the coating layer is high and the coating amount is very small.

Korean Patent Publication No. 10-2004-0016097 Korean Patent Publication No. 10-2007-0104802 Korean Patent Publication No. 10-2011-0059946

Accordingly, it is an object of the present invention to provide metal particles having a core-shell structure in which a coating layer such as silver (Ag) constituting the shell is uniformly coated (plated) and coated in a large amount, and a method for producing the same.

According to an aspect of the present invention,

(1) obtaining a first metal solution comprising first metal particles;

(2) obtaining a second metal coating liquid;

(3) obtaining a reducing solution containing a reducing agent; And

(4) repeating the step of alternately injecting the second metal coating solution and the reducing solution into the first metal solution.

In this case, the step (1) may include a step of removing an oxide film on the surface of the first metal particles, and a step of dispersing the first metal particles from which the oxide film has been removed in water. The oxide film may be removed by acid treatment of the first metal particles.

In addition, the second metal coating solution may include a second metal complex compound prepared by mixing a second metal precursor and a ligand providing compound. At this time, the second metal precursor may include, for example, a silver (Ag) precursor, and the ligand providing compound may be at least one selected from ammonia water and ammonium salts.

In the step (4), the second metal plating solution and the reducing solution may be added to the first metal solution, followed by repeating the cycle of waiting for 1 to 5 minutes. This cycle process can be repeated 20 to 500 times.

The present invention also provides a core-shell metal particle having a core-shell structure in which the second metal is 10 to 60 wt% of the total weight of the metal particles, Lt; / RTI > In this case, the second metal may be coated on the surface of the first metal particle with nanometer-sized particles.

According to the present invention, the coating layer such as silver (Ag) constituting the shell is uniformly coated (plated). In addition, the amount of coating is increased.

1 to 3 are FESEM (Field Emission Scanning Electron Microscope) photographs of silver (Ag) coated nickel (Ni) particles prepared according to an embodiment of the present invention.

In explaining the present invention, the core-shell metal particles according to the present invention will be explained together with the description of the production method according to the present invention.

The method for producing a core-shell metal particle according to the present invention comprises the steps of (1) obtaining a first metal solution containing first metal particles, (2) obtaining a second metal coating liquid (plating liquid), (3) And (4) repeating the step of putting the second metal coating solution and the reducing solution into the first metal solution alternately. At this time, the steps (1) to (3) are not limited to the order. That is, in the production of the first metal solution, the second metal coating solution (plating solution) and the reducing solution, the order of production thereof is not limited. An exemplary form of each step will now be described.

(1) Production of first metal solution

Thereby obtaining a first metal solution containing the first metal particles. The first metal particles constitute a core. The first metal solution is obtained, for example, by dispersing the first metal particles in water. Although not particularly limited, the first metal solution may be obtained by dispersing 5 to 50 parts by weight of the first metal particles in 100 parts by weight of water, for example.

The first metal particles are not particularly limited, and may be selected from various metals (alloys containing a single metal or two or more single metals). In this case, among the various metals, in the case of copper (Cu), galvanic corrosion can be accelerated to a high degree. Therefore, in selecting the first metal particles, it is preferable that the metal is selected from metals other than copper . The first metal particles may be selected from, for example, nickel (Ni), tungsten (W), aluminum (Al), and alloys thereof. More specifically, the first metal particles may be selected from nickel (Ni) particles.

In addition, the first metal particles may have, for example, a spherical shape. In the present invention, a spherical shape does not mean a complete spherical shape. The first metal particles are not particularly limited, but preferably have an average size (diameter) of 0.1 mu m (micrometer) to 20 mu m, for example.

At this time, if the size of the first metal particles is less than 0.1 mu m, a bundling phenomenon may occur in the coating process of the second metal. That is, when the first metal particles are less than 0.1 탆, the particles are aggregated and enlarged like a grape clusters. For example, when the first metal particles are made into paste and applied / heat-treated on a silicon wafer and applied as an electrode, And the efficiency of the battery cell is lowered (that is, the gap of the electrode becomes larger and the electrical conductivity is lowered). If the size of the first metal particles is more than 20 μm, for example, when the electrode is used as an electrode by applying paste / heat treatment on a silicon wafer after being made into a paste, the electrode surface becomes uneven, The adhesion between the ribbon and the electrode may be reduced to increase the resistance (i.e., increase the resistance due to the decrease in adhesion to the ribbon due to the lack of surface properties). Considering this point, it is more preferable that the first metal particles have a size of 1.0 탆 to 10 탆.

It is preferable that the first metal particles have an oxide film (for example, NiO film or the like) present on the surface thereof removed. When an oxide film is formed on the surface of the first metal particles, the coating amount (plating amount) of the second metal may be lowered. The removal of the oxide film can be realized, for example, by etching. The etching may be selected from an acid treatment, a plasma treatment, and a laser irradiation.

According to an exemplary embodiment of the present invention, the removal of the surface oxide film of the first metal particles is preferably performed through an acid treatment, wherein the acid treatment is performed by etching the first metal particles with an acidic solution, And the first metal particles are etched by being dispersed and left in an acidic solution for 10 minutes to 2 hours. The acidic solution may be selected from a solution containing at least one selected from, for example, nitric acid, sulfuric acid and hydrochloric acid.

In the acid treatment, for example, 3 to 30 parts by weight of first metal particles (for example, Ni particles) are dispersed in 100 parts by weight of water, 2 to 15 parts by weight of an acidic solution is added thereto, And then performing an etching process. A more specific example, the acid treatment is 0.2 ~ 1.0 M (g / mol ) , but using the nitric acid (aqueous solution) at a concentration, the first metal particles and the nitric acid 1: 0.1 to 0.5 (e. G., HNO ₃ / Ni = 0.1 to 0.5) by weight. In this acid treatment, the oxide film (NiO film or the like) of the first metal particles (for example, Ni particles) is effectively removed and the coating amount of the second metal (for example, silver (Ag) It can be uniformly coated.

(2) Production of second metal coating liquid

The second metal coating liquid (plating liquid) is required to be able to generate the second metal by the reduction reaction. At this time, the second metal is coated (plated) on the surface of the first metal particle (core) in its production process to form a shell. Such a second metal is plated (coated) on the surface of the first metal particle (core), for example, in a particle size of nanometer (nm) size. The second metal may also have an average size of, for example, 1 nm to 1,000 nm, more specifically 10 nm to 500 nm. The second metal is not particularly limited but may be selected from, for example, silver (Ag), gold (Au), platinum (Pt) and palladium (Pd).

According to an exemplary embodiment of the present invention, the second metal coating liquid comprises a second metal complex. As a specific example, the second metal coating liquid is prepared to include a second metal complex compound prepared by mixing a second metal precursor with a ligand providing compound. More specifically, for example, the second metal coating liquid is prepared by dissolving a second metal precursor in water and then adding and mixing a ligand-providing compound thereto to form a second metal coating liquid on an aqueous solution containing the second metal complex Can be obtained.

The second metal precursor may be one having at least one second metal in the molecule, for example, at least one metal element selected from silver (Ag), gold (Au), platinum (Pt) and palladium (Pd) It is not limited. The second metal precursor may be selected from, for example, a silver (Ag) precursor containing silver (Ag) in the molecule or a palladium (Pd) precursor containing palladium (Pd). More specifically, for example, the second metal precursor may be a silver (Ag) salt such as AgNO ₃ , AgBF ₄ , AgCF ₃ SO ₃ , AgClO ₄ , AgOAc and AgPF ₆ ; And palladium (Pd) salts such as palladium chloride, tetraamine palladium nitrate and palladium sulfamate.

Provided that the ligand providing compound is capable of reacting with a second metal precursor (e.g., silver (Ag) salt, etc.) to form a second metal complex compound (e.g., silver (Ag) complex, etc.). Ligand compounds are provided, for example, aqueous ammonia (NH ₄ OH) and ammonium salts can be used at least one selected from the like (e. G., Ammonium sulfate, ammonium nitrate and ammonium chloride, etc.). Such a ligand providing compound may react with an Ag precursor, for example, to form an ammonium-silver (Ag) complex (e.g., Ag (NH ₃ ) ₂ NO _3, etc.).

(3) Preparation of reducing solution

The reducing solution includes at least a reducing agent. The reducing solution may be selected from, for example, an aqueous solution containing a reducing agent mixed with water. At this time, though not particularly limited, a reducing solution can be obtained through a step of mixing 0.05 to 10.0 parts by weight of a reducing agent with respect to 100 parts by weight of water.

The reducing agent is not limited as long as it is capable of reducing a complex of a second metal solution (e.g., a silver (Ag) complex, etc.) to form a second metal (for example, silver (Ag) nanoparticles). The reducing agent is, for example, hydrazine in _{(N 2 H 4), Ag} (NH 3) 2 NO 3, NaBH 4, LiBH 4, tetrabutyl ammonium borohydride, dimethylformamide, tannic acid, glycol, glycerol, glucose, Rochelle salt, stearate, formaldehyde, and formalin, etc. may be used. Also, in the present invention, the reducing agent includes a hydrate of the above listed materials, for example, hydrazine monohydrate (N ₂ H ₄ .H ₂ O) and the like.

(4) Mixing of solutions

After each solution is prepared as described above, the second metal coating solution and the reducing solution are added to the first metal solution and mixed. At this time, when the solution is introduced, the second metal coating liquid and the reducing solution are alternately supplied, and this process is repeated. More specifically, the second metal coating solution and the reducing solution are repeatedly injected into the first metal solution several times alternately. According to the present invention, by repeating this alternate injection, the second metal is coated with a uniform thickness on the surface of the first metal to have a good core-shell structure. Also, the amount of coating of the second metal is increased.

According to a preferred embodiment, the cycle of the second metal coating solution and the reducing solution are alternately applied to the first metal solution, and then the process of waiting for 1 to 5 minutes is repeated. More specifically, the second metal coating solution is first introduced into the first metal solution, the reducing solution is then introduced (or the reducing solution is first introduced into the first metal solution, and then the second metal coating solution is introduced) To 5 minutes is referred to as a " cycle process ", and this cycle process is repeated several times. For example, the cycle process may be repeated 20 to 500 times. At this time, the dosage may be 0.5 to 3.0 ml each time. That is, the second metal coating solution and the reducing solution may be repeatedly injected in several times at intervals of 0.5 to 3.0 ml / one time.

The total amount of the second metal coating solution and the reducing solution to be added to the first metal solution is not particularly limited, but the first metal solution 100 30 to 80 parts by weight of the second metal coating liquid, and 30 to 80 parts by weight of the reducing solution may be added. At this time, the second metal coating liquid and the reducing solution are added step by step in consideration of the stoichiometric value depending on the kind of the second metal complex (silver (Ag) complex compound) contained therein and the reducing agent It is good.

Meanwhile, the metal particles of the core-shell structure according to the present invention have a core-shell structure in which a surface of a first metal particle (core) is coated with a second metal (shell) Is 10 to 60% by weight of the total weight of the particles. Preferably, the content of the second metal is 30% by weight or more, specifically 30 to 60% by weight, based on the total weight of the metal particles. In addition, the second metal is coated with particles of nanometer (nm) size. In addition, the metal particles of the core-shell structure according to the present invention can be produced through the above-described production method according to the present invention.

According to the present invention described above, metal particles having a core-shell structure having a uniform coating layer can be easily produced by an efficient process. That is, a coating layer (shell) of the second metal is coated on the surface of the first metal particle (core) with a uniform thickness. In addition, the second metal has a particle size of nanometer (nm) size, and the coating amount is increased. That is, the content of the second metal accounts for not less than 10 wt%, preferably not less than 30 wt% of the total weight of the metal particles of the core-shell structure. As described above, when the coating amount (content) of the second metal is large, the characteristics of the second metal can be effectively imparted. For example, when the second metal is silver (Ag), the amount of silver (Ag) coating is large, so that it has excellent electrical conductivity and antibacterial property.

In addition, the metal particles of the core-shell structure according to the present invention can be applied to various fields, and their application fields are not limited. For example, it can be applied to various applications such as a conductive material of various electronic products, an electromagnetic wave shielding material, and an antibacterial material.

Hereinafter, examples and comparative examples of the present invention will be exemplified. The following examples are provided to illustrate the present invention in order to facilitate understanding of the present invention, and thus the technical scope of the present invention is not limited thereto. In the following examples, it is exemplified that substantially spherical Ni particles are used for the first metal (core) and silver (Ag) is coated for the second metal (shell). In the following examples, D ₅₀ is the median diameter of the entire Ni particles.

[Example 1]

30 g of Ni particles (D ₅₀ = 6.3 탆) were dispersed in 200 g of water. Then, 15 g of nitric acid (70 wt% aqueous solution) was injected thereinto and subjected to an etching treatment for 1 hour to remove the oxide film on the surface of the Ni particles. Thereafter, the filtrate was removed, Ni particles were separated, and the separated Ni particles were dispersed again in 200 g of water. (Preparation of solution A)

After dissolving 45 g of AgNO ₃ in water, NH ₄ OH was added thereto to prepare an ammonium-silver (Ag) complex (Ag (NH ₃ ) ₂ NO ₃ ) solution with a total volume of 150 ml. (Preparation of solution B)

Water was added to 3.31 g of hydrazine monohydrate (N ₂ H ₄ .H ₂ O) to prepare a solution having a total volume of 150 ml. (Preparation of solution C)

2 ml of the prepared solution B and solution C were sequentially added to the solution A, followed by waiting for 3 minutes. Thereafter, 2 ml of the solution B and the solution C were sequentially added to the solution A, and the process of waiting for 3 minutes was repeated to add the solution B and the solution C to the solution A, and Ag nanoparticles were coated on the Ni particles Ni particle synthesis).

As a result of ICP analysis after coating, Ag-coated Ni particles having a silver (Ag) content of 53.5 wt% were synthesized in the total weight of the Ag coated Ni particles.

[Example 2]

30 g of Ni particles (D ₅₀ = 6.3 탆) were dispersed in 200 g of water. Then, 15 g of nitric acid (70 wt% aqueous solution) was injected thereinto and subjected to an etching treatment for 1 hour to remove the oxide film on the surface of the Ni particles. Thereafter, the filtrate was removed, Ni particles were separated, and the separated Ni particles were dispersed again in 200 g of water. (Preparation of solution A)

30 g of AgNO ₃ was dissolved in water and NH ₄ OH was added thereto to prepare a solution of ammonium-silver (Ag) complex (Ag (NH ₃ ) ₂ NO ₃ ) in a total volume of 100 ml. (Preparation of solution B)

Water was added to 2.21 g of hydrazine monohydrate (N ₂ H ₄ .H ₂ O) to prepare a solution having a total volume of 100 ml. (Preparation of solution C)

1 ml of the solution B and the solution C were sequentially added to the solution A, followed by waiting for 2 minutes. Thereafter, the solution B and the solution C were sequentially added to the solution A in an amount of 1 ml each, and then the process of waiting for 2 minutes was repeated to add the solution B and the solution C to the solution A, and Ag nanoparticles were coated on the Ni particles Ni particle synthesis).

As a result of ICP analysis after coating, Ag-coated Ni particles having a silver (Ag) content of 40.6 wt% were synthesized in the total weight of the Ag-coated Ni particles.

[Example 3]

30 g of Ni particles (D ₅₀ = 1.2 탆) were dispersed in 200 g of water. Then, 6 g of nitric acid (70 wt% aqueous solution) was injected thereinto and subjected to an etching treatment for 1 hour to remove the oxide film on the surface of the Ni particles. Thereafter, the filtrate was removed, Ni particles were separated, and the separated Ni particles were dispersed again in 200 g of water. (Preparation of solution A)

After dissolving 45 g of AgNO ₃ in water, NH ₄ OH was added thereto to prepare a solution of an ammonium-silver (Ag) complex (Ag (NH ₃ ) ₂ NO ₃ ) in a total volume of 120 ml. (Preparation of solution B)

Water was added to 3.31 g of hydrazine monohydrate (N ₂ H ₄ .H ₂ O) to prepare a solution with a total volume of 120 ml. (Preparation of solution C)

1 ml of the solution B and the solution C were sequentially added to the solution A, followed by waiting for 2 minutes. Thereafter, the solution B and the solution C were sequentially added to the solution A in an amount of 1 ml each, and then the process of waiting for 2 minutes was repeated to add the solution B and the solution C to the solution A, and Ag nanoparticles were coated on the Ni particles Ni particle synthesis).

As a result of ICP analysis after coating, Ag-coated Ni particles having a silver (Ag) content of 50.7 wt% were synthesized in the total weight of the Ag-coated Ni particles.

[Example 4]

10 g of Ni particles (D ₅₀ = 1.2 탆) were dispersed in 100 g of water. (Preparation of solution A)

After dissolving 10 g of AgNO ₃ in water, NH ₄ OH was added thereto to prepare a solution of ammonium-silver (Ag) complex (Ag (NH ₃ ) ₂ NO ₃ ) in a total volume of 40 ml. (Preparation of solution B)

Water was added to 0.74 g of hydrazine monohydrate (N ₂ H ₄ .H ₂ O) to prepare a solution having a total volume of 40 ml. (Preparation of solution C)

1 ml of the solution B and the solution C prepared above were sequentially added to the solution A, and then the solution was waited for about one minute. Thereafter, 1 ml of Solution B and Solution C were sequentially added to Solution A, and the process of waiting for 1 minute was repeated to add Solution B and Solution C to Solution A. All of the Ni particles were coated with Ag nanoparticles Ni particle synthesis).

As a result of ICP analysis after coating, Ag-coated Ni particles having a silver (Ag) content of 38.9 wt% were synthesized in the total weight of the Ag coated Ni particles.

[Comparative Example 1]

10 g of Ni particles (D ₅₀ = 1.2 탆) were dispersed in 100 g of water. (Preparation of solution A)

After dissolving 10 g of AgNO ₃ in water, NH ₄ OH was added thereto to prepare a solution of ammonium-silver (Ag) complex (Ag (NH ₃ ) ₂ NO ₃ ) in a total volume of 40 ml. (Preparation of solution B)

Water was added to 0.74 g of hydrazine monohydrate (N ₂ H ₄ .H ₂ O) to prepare a solution having a total volume of 40 ml. (Preparation of solution C)

The prepared solution B and solution C were all added to Solution A, and Ni particles were coated with Ag nanoparticles (Ag coated Ni particles).

As a result of ICP analysis after coating, Ag-coated Ni particles having a silver (Ag) content of 40.1 wt% were synthesized in the total weight of the Ag coated Ni particles.

The uniformity of the Ag particles was visually observed and evaluated by FESEM (Field Emission Scanning Electron Microscope) photographs of the Ag-coated Ni particles according to each of the Examples and Comparative Examples. At this time, when the shape of the Ag-coated Ni particles was nearly spherical, it was evaluated as "uniform ", otherwise it was evaluated as" non-uniform ". The above results are shown in Table 1 below. 1 to 3 show FESEM photographs of the Ni-coated Ag particles prepared according to Example 1 (FIG. 1), Example 2 (FIG. 2) and Example 3 (FIG. 3).

≪ Evaluation results of uniformity of silver-coated Ni particles and silver (Ag) content > Remarks
Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Uniformity
Uniformity Uniformity Uniformity Uniformity Unevenness The silver (Ag) content
53.5 wt% 40.6 wt% 50.7 wt% 38.9 wt% 40.1 wt%

In the examples according to the present invention, silver (Ag) nanoparticles were used in the present invention even though Ni particles having a small particle size of 6.3 mu m or 1.2 mu m were used as shown in Table 1 and the accompanying drawings. It can be seen that the surface of the Ni particles was uniformly coated. In addition, in the case of the embodiments according to the present invention, it can be seen that the content of silver (Ag) is higher than 30 wt% and more than 50 wt%.

Claims (19)

(1) a step of using nitric acid having a concentration of 0.2 to 1.0 M (g / mol), mixing nickel metal particles and nitric acid at a weight ratio of 1: 0.1-0.5 to remove the oxide film on the surface of the nickel metal particles, Dispersing the removed nickel metal particles in water; obtaining a first metal solution;
(2) obtaining a second metal coating solution comprising a complex prepared by mixing a silver (Ag) precursor and a ligand providing compound;
(3) obtaining a reducing solution containing a reducing agent; And
(4) repeating the step of putting the second metal coating liquid and the reducing solution into the first metal solution alternately.
delete delete delete delete delete delete delete delete delete The method according to claim 1,
Wherein the silver (Ag) precursor is at least one selected from AgNO ₃ , AgBF ₄ , AgCF ₃ SO ₃ , AgClO ₄ , AgOAc and AgPF ₆ .
The method according to claim 1,
Wherein the ligand providing compound is at least one selected from ammonia water and ammonium salts.
The method according to claim 1,
The reducing agent may be at least one selected from the group consisting of hydrazine (N ₂ H ₄ ), hydrazine monohydrate (N ₂ H ₄ .H ₂ O), Ag (NH ₃ ) ₂ NO ₃ , NaBH ₄ , LiBH ₄ , tetrabutylammonium, borohydride, Wherein the core-shell metal particle is at least one selected from the group consisting of amide, tannic acid, glycol, glycerol, glucose, rochel, salt of strontium, formaldehyde and formalin.
The method according to claim 1,
The step (4)
And the second metal coating liquid and the reducing solution are added to the first metal solution, and then the cycle of waiting for 1 minute to 5 minutes is repeated.
15. The method of claim 14,
Wherein the cycle step is repeated 20 to 500 times.
A metal particle of a core-shell structure produced by a manufacturing method according to any one of claims 1 and 11 to 15,
Wherein the second metal is 10 to 60 wt% of the total weight of the metal particles.
17. The method of claim 16,
Wherein the second metal is 30 to 60 wt% of the total weight of the metal particles.
17. The method of claim 16,
Wherein the second metal is coated on the surface of the first metal particle with nanometer-sized particles.
delete

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