Micron silver particles having a nanoscale rod-like structure on the surface and a method for preparing the same

Abstract

The application provides a micron silver particle with a nanoscale rod-shaped structure on the surface and a preparation method of the micron silver particle, and the preparation method comprises the following steps: configuring a precursor solution containing a silver source and a coating agent; configuring a reducing solution containing a reducing agent; mixing the reducing solution and the precursor solution at 25-60 DEG C, performing a redox reaction for 0.1-2.5 h, adding a self-assembly active agent to perform a reaction for 1-2 h, centrifuging, taking a precipitate, cleaning, and drying to obtain the micron silver particle with the nanoscale rod-shaped structure on the surface; wherein the self-assembly active agent is at least one of sodium carbonate, sodium nitrate and sodium sulfate, and the molar ratio of silver ions to the self-assembly active agent is 5.0-10.0. By adopting the technical scheme, the micron silver particle with the nanoscale rod-shaped structure on the surface is obtained, and the particle size and shape are uniform and stable, and the dispersibility is good.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of micro-nano metal materials, and particularly relates to a micro silver particle with a nano-scale rod-shaped structure on the surface and a preparation method thereof. BACKGROUND

[0002] Nanometer materials have nanometer size effects due to their size of 1-100 nm, and the melting point of nanometer metal materials is significantly reduced and has some special physical and chemical properties. Among various nanometer metals, nanometer silver is widely used in many fields such as biological medicine, catalysis, optics, electronic packaging, electromagnetic shielding, and flexible materials due to its high thermal conductivity, high electrical conductivity, antibacterial and bactericidal properties, excellent catalytic activity, and other special physical and chemical properties. The synthesis and preparation of nanometer silver particles have always been a popular field of research for many material scholars. The common preparation methods of nanometer silver particles at present mainly include chemical methods such as liquid phase reduction method, and physical methods such as cryogenic ball milling method and high-temperature ball milling method. The surface of the nanometer silver particles obtained by these preparation methods is coated with an organic coating layer to prevent the nanometer silver particles from agglomerating. The existing chemical preparation method can prepare spherical, triangular, cubic, tetrahedral, octahedral, decagonal, linear, and rod-shaped nanometer silver particles. However, due to the high surface energy of nanometer silver particles, agglomeration often occurs despite the presence of a coating agent. The agglomeration of nanometer silver particles will cause them to lose nanometer size effects and lose activity, affecting their use. In contrast, micro metal materials are generally prepared by physical methods and have good dispersibility and uniform size due to the space hindrance caused by their large size, but their size is relatively large and their activity is poor compared to nanometer materials.

[0003] At the same time, there are certain problems in the size uniformity control and batch production of nanometer silver particles. Micro silver particles can be produced in batches, but they lack the unique physical and chemical properties brought by nanometer size effects. It is particularly important to combine the advantages of nanometer silver particles and micro silver particles and provide a micro silver particle preparation process with a nano-scale structure, low cost, and simple process. SUMMARY

[0004] In view of the above technical problems, the present application discloses a preparation method of a micro silver particle with a nano-scale rod-shaped structure on the surface. The space hindrance effect caused by the micro-scale size of the obtained micro silver particle can effectively solve the particle agglomeration problem, and the nano-scale rod-shaped structure on the surface of the particle can provide higher surface activity and higher specific surface area.

[0005] To this end, the technical solution adopted by the present application is as follows:

[0006] A method for preparing micron silver particles having a nanoscale rod-like structure on the surface comprises the following steps:

[0007] Step S1, preparing a precursor solution, wherein the precursor solution contains a silver source and a coating agent;

[0008] preparing a reducing solution, wherein the reducing solution contains a reducing agent;

[0009] Step S2, mixing the reducing solution and the precursor solution at 25-60° C., performing an oxidation-reduction reaction for 0.1-2.5 hours, adding a self-assembly active agent, reacting for 1-2 hours, centrifuging, collecting the precipitate, washing, and drying to obtain micronized silver particles with a nanoscale rod-like structure on the surface;

[0010] The self-assembly active agent is at least one of sodium carbonate, sodium nitrate and sodium sulfate, and the molar ratio of silver ions in the precursor solution to the self-assembly active agent is 5.0 to 10.0.

[0011] As a further improvement of the present invention, step S1 also includes preparing a self-assembly active agent solution. In step S2, the self-assembly active agent is added in the form of a self-assembly active agent solution, and the solvent of the self-assembly active agent solution is one or more of water, ethanol, ethylene glycol, and diethylene glycol.

[0012] As a further improvement of the present invention, in step S2, the stirring speed of the mixing is 250 to 1000 r / min.

[0013] As a further improvement of the present invention, in the precursor solution, the molar ratio of silver ions to the coating agent is 0.5 to 2.0.

[0014] As a further improvement of the present invention, in the precursor solution, the concentration of the silver ions is 0.1 to 1.25 mol / L. In step S2, the precursor solution is added dropwise to the reducing solution at a rate of 0.15 ml to 2 mL / s.

[0015] As a further improvement of the present invention, in step S2, the molar ratio of the silver ions in the precursor solution to the reducing agent in the reducing solution is 0.1-1.

[0016] As a further improvement of the present invention, in step S1, the silver source is at least one of silver nitrate, silver acetylacetonate, silver bromate, silver bromide, silver chloride, silver citrate, silver fluoride, silver iodate, silver iodide, silver nitrite, silver oxalate, silver carbonate, silver nitrite, silver phosphate, silver chlorate, silver perchlorate and silver tetrafluoroborate; and the coating agent is at least one of citric acid, sodium citrate, polyvinyl pyrrolidone, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, dodecyl mercaptan, polyethylene glycol and polyacrylic acid.

[0017] As a further improvement of the present invention, the reducing agent is at least one of sodium borohydride, hydrazine hydrate, citric acid, formic acid, sodium citrate, disodium citrate, ferrous sulfate, ascorbic acid, sodium ascorbate, hydroxylamine, aniline, glucose, ethylene glycol, polyethylene glycol, glycerol, polyvinyl pyrrolidone, and sodium sulfite.

[0018] As a further improvement of the present invention, the solvent of the precursor solution is at least one of water, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, isopentanol, diethylene glycol, toluene and xylene.

[0019] As a further improvement of the present invention, the solvent of the reducing solution is at least one of water, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, isopentanol, diethylene glycol, toluene and xylene.

[0020] As a further improvement of the present invention, in step S2, the cleaning is performed by centrifugation 4 times with deionized water or anhydrous ethanol at a rotation speed of 2500-5000 r / min. After the cleaning is completed, the product is dried at 45-55°C for 10-12 hours under a vacuum degree of less than 0.01 MPa.

[0021] The present invention also discloses a micron silver particle having a nano-scale rod-like structure on the surface, which is prepared by using any of the above methods for preparing micron silver particles having a nano-scale rod-like structure on the surface.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] First, the technical solution of the present invention is to first mix a silver source and a coating agent to obtain a precursor solution, then prepare a certain amount of reducing solution, and then mix the precursor solution and the reducing solution to produce an oxidation-reduction reaction. The added coating agent will coat the specific surface of the silver seed crystal, so that the subsequently reduced silver will be selectively deposited, thereby forming rod-shaped nanosilver particles. Subsequently, with the addition of a self-assembly active agent, the addition of the self-assembly active agent will form a competitive relationship with the silver particles for the coating agent, and gradually form a good combination with the coating agent, so that the organic coating on the surface of the nanorod-shaped silver particles is gradually desorbed, and the exposed crystal surface contacts and diffuses with the exposed crystal surface of other nanorod-shaped silver particles to complete self-assembly, forming micron silver particles with a nanoscale rod-shaped structure on the surface.

[0024] Second, the preparation process of the technical solution of the present invention is green and low-consumption. The surface of the prepared micron silver particles has a unique rod-shaped nanostructure and the particle size and shape are uniform and stable, with good dispersibility. It can be mass-produced and can be applied to electronic packaging, catalysis, antibacterial and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a field emission scanning electron microscope (SEM, ×50000) image of the micron silver particles obtained in Example 1 of the present invention.

[0026] Figure 2 This is a field emission scanning electron microscope (SEM, ×5000) image of the micron silver particles obtained in Example 1 of the present invention.

[0027] Figure 3 This is a field emission scanning electron microscope (SEM, ×50000) image of the internal structure of the micron silver particles in Example 1 of the present invention.

[0028] Figure 4 1 is the XRD pattern of the micron silver particles in Example 1 of the present invention.

[0029] Figure 5 This is a field emission scanning electron microscope (SEM, ×20000) image of the micron silver particles in Example 6 of the present invention.

[0030] Figure 6 This is a field emission scanning electron microscope image of the silver particles obtained in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described in further detail below.

[0032] A micron silver particle having a nanoscale rod-like structure on its surface, wherein the preparation method comprises the following steps:

[0033] Step S1, respectively preparing a precursor solution containing a silver source and a coating agent, a reducing solution containing a reducing agent, and a solution containing a self-assembly active agent;

[0034] Step 2: mixing the precursor solution and the reducing solution and performing an oxidation-reduction reaction at 25° C. to 60° C. for 0.1 to 2.5 hours, adding a self-assembly active agent solution and reacting at 25° C. to 60° C. for another 1 to 2 hours, centrifuging the resulting solution, collecting the precipitate, washing, and drying to obtain micronized silver particles having a nanoscale rod-like structure on the surface;

[0035] Wherein, during the redox reaction, the concentration of silver ions in the precursor solution is 0.1-1.25 mol / L, and the molar ratio of the silver ions in the silver source to the coating agent in the precursor solution is 0.5-2.0.

[0036] During the mixing step S2, the molar ratio of the silver ions in the silver source to the reducing agent in the reducing solution is 0.1 to 1; and the molar ratio of the silver ions in the precursor solution to the self-assembly active agent is 5.0 to 10.0. Furthermore, the redox reaction is carried out under stirring at a stirring rate of 250 to 1000 rpm.

[0037] In the precursor solution, the silver source is one or more of silver nitrate, silver acetylacetonate, silver bromate, silver bromide, silver chloride, silver citrate, silver fluoride, silver iodate, silver iodide, silver nitrite, silver oxalate, silver carbonate, silver nitrite, silver phosphate, silver chlorate, silver perchlorate and silver tetrafluoroborate; and the coating agent is one or more of citric acid, sodium citrate, polyvinyl pyrrolidone, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, dodecyl mercaptan, polyethylene glycol and polyacrylic acid.

[0038] The solvents of the precursor solution and the reducing solution are independently selected from one or more of water, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, isopentanol, diethylene glycol, toluene and xylene.

[0039] In the reducing solution, the reducing agent is selected from one or more of sodium borohydride, hydrazine hydrate, citric acid, formic acid, sodium citrate, disodium citrate, ferrous sulfate, ascorbic acid, sodium ascorbate, hydroxylamine, aniline, glucose, ethylene glycol, polyethylene glycol, glycerol, polyvinyl pyrrolidone, and sodium sulfite.

[0040] In the self-assembly active agent solution, the self-assembly active agent is selected from one or more of sodium carbonate, sodium nitrate, and sodium sulfate, and the solvent of the self-assembly active agent solution is selected from one or more of water, ethanol, ethylene glycol, and diethylene glycol.

[0041] Preferably, mixing the precursor solution and the reducing agent solution comprises:

[0042] The precursor solution is heated to 25° C. to 60° C., and then the reducing solution is added dropwise to the precursor solution; or, the reducing solution is heated to 25° C. to 60° C., and then the precursor solution is added dropwise to the reducing solution.

[0043] Preferably, the redox reaction time is 0.1 to 2.5 hours, and after the redox reaction is completed, the self-assembly active agent solution is added dropwise and then the self-assembly reaction is continued for 1 to 2 hours.

[0044] Preferably, the system after the self-assembly reaction is centrifuged to obtain a precipitate, which is then washed with deionized water or anhydrous ethanol. The centrifugal washing conditions are 4 times of 4 minutes each at 2500-5000 r / min. After washing, the system is dried at 50° C. for 10-12 hours under a vacuum degree of less than 0.01 MPa to obtain the micronized silver particles.

[0045] Example 1

[0046] 3.4g of silver nitrate and 1.20g of polyvinyl pyrrolidone were dispersed in 25ml of deionized water and stirred to form a precursor solution. 3.04g of ferrous sulfate was then dispersed in 25ml of deionized water and stirred to form a reducing solution. 0.40g of sodium sulfate was then dispersed in 10ml of deionized water to form a self-assembly active agent solution. The reducing solution was added dropwise to the precursor solution at a rate of 1mL / s while stirring at 800r / min at room temperature. After reacting for 10 minutes, the self-assembly active agent solution was added dropwise to the reaction system at a rate of 1mL / s. The reaction continued for another 30 minutes. After the reaction was completed, the precipitate was centrifuged and washed three times with deionized water at 3500r / min and then once with anhydrous ethanol. The precipitate was then dried at 50°C for 11 hours under a vacuum of less than 0.01MPa to obtain micronized silver particles with a nanorod-like structure.

[0047] The micron silver particles with nano-rod-like structures on the surface were taken and the morphology of the particles was observed using a field emission scanning electron microscope (SEM) and the phase spectrum was analyzed using an X-ray diffractometer (XRD). The results were Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown. Figure 1 It can be seen that there are a large number of nano-scale rod-like structures on the surface of micron silver particles, and the nano-scale rod-like structures are evenly distributed on the surface of micron silver particles; Figure 2 It can be seen that the micron silver particles have good dispersion, no obvious agglomeration, uniform particle size and shape. Figure 3 It can be seen that the micron silver particles are self-assembled from nano silver rods, and the interior is a nano silver rod structure. Figure 4 The characteristic peaks of metallic silver can be seen, but there are no characteristic peaks of silver oxide or second phase substances.

[0048] Example 2

[0049] 6.8g of silver nitrate and 6.88g of sodium citrate were dispersed in 75ml of deionized water and stirred to form a precursor solution. 8.10g of ferrous sulfate was then dispersed in 50ml of deionized water and stirred to form a reducing solution. 0.35g of sodium nitrate was then dispersed in 15ml of deionized water to form a self-assembly active agent solution. The reducing solution was added dropwise to the precursor solution at a rate of 0.5mL / s while stirring at 600r / min at room temperature. After reacting for 20min, the self-assembly active agent solution was added dropwise to the reaction system at a rate of 0.5mL / s. The reaction continued for another 20min. After the reaction was completed, the mixture was washed three times with deionized water at 3500r / min and then once with anhydrous ethanol. The precipitate was then dried at 50°C for 11h under a vacuum of less than 0.01MPa to obtain micronized silver particles with a nanorod-like structure.

[0050] The SEM image, XRD pattern and internal structure of the prepared micron silver particles are similar to those in Example 1, indicating that the physical phase of the micron silver particles is metallic silver alone, without other impurities, and the particles do not agglomerate, are well dispersed, and have uniform particle size.

[0051] Example 3

[0052] 3.4g of silver nitrate and 3.44g of sodium citrate were dispersed in 50ml of deionized water and stirred to form a precursor solution. 16.48g of ascorbic acid was then dispersed in 50ml of deionized water and stirred to form a reducing solution. 0.32g of sodium nitrate was then dispersed in 10ml of deionized water to form a self-assembly active agent solution. The reducing solution was added dropwise to the precursor solution at a rate of 0.5mL / s while stirring at 400r / min in a 50°C water bath. After a 30-minute reaction, the self-assembly active agent solution was added dropwise to the reaction system at a rate of 0.5mL / s. The reaction continued for 1.5h. After the reaction was complete, the mixture was washed three times with deionized water at 4000r / min and then once with anhydrous ethanol. The precipitate was then dried at 50°C for 10h under a vacuum of less than 0.01MPa to obtain micronized silver particles with a nanorod-like structure.

[0053] The SEM image, XRD pattern and internal structure of the prepared micron silver particles are similar to those in Example 1, indicating that the physical phase of the micron silver particles is metallic silver alone, without other impurities, and the particles do not agglomerate, are well dispersed, and have uniform particle size.

[0054] Example 4

[0055] 1.7g silver nitrate and 1.15g polyvinyl pyrrolidone were dispersed in 25ml ethylene glycol and stirred to form a precursor solution. 2.0g ascorbic acid was then dispersed in 25ml ethylene glycol and stirred to form a reducing solution. 0.11g sodium nitrate was then dispersed in 5ml ethylene glycol to form a self-assembly active agent solution. The reducing solution was added dropwise to the precursor solution at a rate of 0.5mL / s while stirring at 400r / min in a water bath at 60°C. After a 0.5h reaction, the self-assembly active agent solution was added dropwise to the reaction system at a rate of 0.5mL / s. The reaction continued for another 1.5h. After the reaction was complete, the mixture was washed three times with deionized water at 3500r / min and once with anhydrous ethanol. The precipitate was then dried at 50°C for 10h under a vacuum of less than 0.01MPa to obtain micronized silver particles with a nanorod-like structure.

[0056] The SEM image, XRD pattern and internal structure of the prepared micron silver particles are similar to those in Example 1, indicating that the physical phase of the micron silver particles is metallic silver alone, without other impurities, and the particles do not agglomerate, are well dispersed, and have uniform particle size.

[0057] Example 5

[0058] 2.55g of silver nitrate and 2.3g of citric acid were dispersed in 40ml of diethylene glycol and stirred to form a precursor solution. 2.88g of ascorbic acid was then dispersed in 40ml of diethylene glycol and stirred to form a reducing solution. 0.22g of sodium carbonate was then dispersed in 5ml of diethylene glycol to form a self-assembly active agent solution. The reducing solution was added dropwise to the precursor solution at a rate of 0.5mL / s while stirring at 400r / min in a water bath at 60°C. After a 30-minute reaction, the self-assembly active agent solution was added dropwise to the reaction system at a rate of 0.5mL / s. The reaction continued for another 1.5 hours. After the reaction was complete, the mixture was washed three times with deionized water at 3500r / min and then once with anhydrous ethanol. The precipitate was then dried at 50°C for 10 hours under a vacuum of less than 0.01MPa to obtain micronized silver particles with a nanorod-like structure.

[0059] The SEM image, XRD pattern and internal structure of the prepared micron silver particles are similar to those in Example 1, indicating that the physical phase of the micron silver particles is metallic silver alone, without other impurities, and the particles do not agglomerate, are well dispersed, and have uniform particle size.

[0060] Comparative Example 1

[0061] The difference between Comparative Example 1 and Example 1 is that the mass of sodium sulfate added in Example 1 is changed to 0.57 g, and other conditions are exactly the same as those in Example 1.

[0062] The morphology of the prepared silver particles is as follows Figure 5 As shown, it can be seen that for this embodiment, due to the excessive addition of the self-assembly active agent, the assembling units will be assembled into micron silver particles, and then the particles will be further assembled to form a sheet structure composed of multiple particles.

[0063] Comparative Example 2

[0064] The difference between Comparative Example 2 and Example 1 is that the mass of sodium sulfate added in Example 1 is changed to 0.25 g.

[0065] No results were obtained after preparation Figure 1 Similar particles were observed to be a large number of rod-shaped and spherical particles, that is, due to the small amount of self-assembly active agent added, the smallest assembly units were unable to spontaneously assemble together.

[0066] As demonstrated by the above examples and comparative examples, the method of the present invention produces micronized silver particles with a nanorod-like surface structure, using relatively low-cost raw materials as reactants, under low-cost, environmentally friendly reaction conditions, and with a simple preparation process. Furthermore, the resulting micronized silver particles exhibit excellent dispersibility, a consistent nanorod-like surface structure, and are suitable for mass production and application in electronic packaging materials, catalysis, and other fields.

[0067] Comparative Example 3

[0068] Based on Example 1, this comparative example is different in that no self-assembly active agent is added to this comparative example.

[0069] No results were obtained after preparation Figure 1 Similar particles were obtained to obtain particles similar to those in Comparative Example 2, that is, without the addition of the self-assembly active agent, the smallest units of the silver particles in the initial stage of the reaction could not self-assemble together, and the silver particles prepared were as follows Figure 6 shown.

[0070] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing micron silver particles having a nanoscale rod-like structure on the surface, characterized in that: The steps include: Step S1, preparing a precursor solution, wherein the precursor solution contains a silver source and a coating agent; preparing a reducing solution, wherein the reducing solution contains a reducing agent; Step S2, mixing the reducing solution and the precursor solution at 25-60° C., performing an oxidation-reduction reaction for 0.1-2.5 hours, adding a self-assembly active agent, reacting for 1-2 hours, centrifuging, collecting the precipitate, washing, and drying to obtain micronized silver particles having a nanoscale rod-like structure on the surface; The self-assembly active agent is at least one of sodium carbonate, sodium nitrate, and sodium sulfate, and the molar ratio of silver ions in the precursor solution to the self-assembly active agent is 5.0-10.0; the coating agent is at least one of citric acid, sodium citrate, polyvinyl pyrrolidone, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, dodecyl mercaptan, polyethylene glycol, and polyacrylic acid.

2. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 1, characterized in that: Step S1 further comprises preparing a self-assembly active agent solution. In step S2, the self-assembly active agent is added in the form of a self-assembly active agent solution, wherein the solvent of the self-assembly active agent solution is one or more of water, ethanol, ethylene glycol, and diethylene glycol.

3. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 1, characterized in that: In the precursor solution, the molar ratio of silver ions to the coating agent is 0.5-2.

0.

4. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 3, characterized in that: In the precursor solution, the concentration of the silver ions is 0.1-1.25 mol / L. In step S2, the precursor solution is added dropwise to the reducing solution at a rate of 0.15 ml-2 mL / s.

5. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 4, characterized in that: In step S2, the molar ratio of the silver ions in the precursor solution to the reducing agent in the reducing solution is 0.1-1.

6. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 1, characterized in that: In step S1, the silver source is at least one of silver nitrate, silver acetylacetonate, silver bromate, silver bromide, silver chloride, silver citrate, silver fluoride, silver iodate, silver iodide, silver nitrite, silver oxalate, silver carbonate, silver phosphate, silver chlorate, silver perchlorate and silver tetrafluoroborate.

7. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 1, characterized in that: The reducing agent is at least one of sodium borohydride, hydrazine hydrate, citric acid, formic acid, sodium citrate, disodium citrate, ferrous sulfate, ascorbic acid, sodium ascorbate, hydroxylamine, aniline, glucose, ethylene glycol, polyethylene glycol, glycerol, polyvinyl pyrrolidone, and sodium sulfite.

8. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 1, characterized in that: The solvent of the precursor solution is at least one of water, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, isoamyl alcohol, diethylene glycol, toluene and xylene; the solvent of the reducing solution is at least one of water, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, isoamyl alcohol, diethylene glycol, toluene and xylene.

9. The method for preparing micron silver particles having a nanoscale rod-like structure on the surface according to claim 1, characterized in that: In step S2, the cleaning is performed by centrifugation 4 times with deionized water or anhydrous ethanol at a rotation speed of 2500-5000 r / min. After the cleaning is completed, the product is dried at 45-55° C. for 10-12 h under a vacuum degree of less than 0.01 MPa.

10. A micron silver particle having a nanoscale rod-like structure on its surface, characterized in that: The silver particles are prepared by the method for preparing micron silver particles having a nano-scale rod-like structure on the surface as claimed in any one of claims 1 to 9.

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