Preparation method of micro-nano copper particles and micro-nano copper particles

Abstract

The present invention belongs to the technical field of micro-nano metal particles, and specifically provides a method for preparing micro-nano copper particles and micro-nano copper particles. The purpose is to solve the problem of poor dispersibility and uneven particle size of micro-nano copper particles obtained by chemical reduction. To this end, the preparation method of the present invention comprises the following steps: S1: dissolving silver seed crystals, coating agents and reducing agents in an alcohol solution, stirring evenly to obtain solution A, and heating solution A through an oil bath; S2: dissolving a copper source in deionized water to obtain solution B; S3: adding solution B to solution A, and then continuing the reaction for a set time to obtain a micro-nano copper solution; S4: centrifuging the micro-nano copper solution obtained in step S3, and drying the particles obtained by centrifugation to obtain micro-nano copper particles. The micro-nano copper particles obtained by the preparation method of the present invention have uniform particle size and good dispersibility, and are not easy to agglomerate.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano metal particles, and specifically provides a preparation method of micro-nano copper particles and the micro-nano copper particles. Background Art

[0002] As the size of metal particles decreases, the proportion of atoms on the metal surface will increase, and the surface energy will be higher than that of macroscopic bulk materials. When the particle size is reduced to the nanometer level, micro-nano particles will have small size effects, surface effects and quantum tunneling effects. These unique effects make micro-nano metal particles have unique application value in the fields of optics, catalysis, energy and semiconductor electronics.

[0003] Micro-nano copper powder has excellent physical and chemical properties, excellent electrical conductivity, stability, and thermal conductivity. It can be used as the main material or important component in typical application scenarios such as conductive slurry metal powder, solid lubricant and additive, antibacterial agent for polymer, etc., and has important market value.

[0004] When preparing micro-nano copper particles by chemical reduction method, the coating agent, reducing agent and temperature are usually prepared together. The adjustment is complicated and the uniformity of particle size cannot be guaranteed, which affects the stability of thermal, electrical and mechanical properties in practical applications. Therefore, how to control uniformly dispersed micro-nano copper particles with controllable particle size is a difficult problem.

[0005] Accordingly, this field requires a new technical solution to solve the above technical problems. Summary of the invention

[0006] The present invention aims to solve the above technical problem, that is, to solve the problem of poor dispersibility and uneven particle size of micro-nano copper particles prepared by chemical reduction method.

[0007] In a first aspect, the present invention provides a method for preparing micro-nano copper particles, the preparation method comprising the following steps: S1: dissolving a silver seed, a coating agent and a reducing agent in an alcohol solution, stirring evenly to obtain a solution A, and heating the solution A in an oil bath; S2: dissolving a copper source in deionized water to obtain a solution B; S3: adding the solution B to the solution A, and then continuing the reaction for a set time to obtain a micro-nano copper solution; S4: centrifuging the micro-nano copper solution obtained in step S3, and drying the particles obtained by centrifugation to obtain micro-nano copper particles.

[0008] In the case of adopting the above technical scheme, the present invention introduces silver seeds, i.e., nano-silver particles, into the reaction solution, so that the silver seeds provide nucleus sites for the reduction of copper ions into copper atoms. The reduced copper atoms are more inclined to nucleate on the solid components in the solution rather than spontaneously nucleate. Thus, the copper atoms nucleate on the nano-silver, which can keep the particle size of the micro-nano copper particles uniform and improve the dispersibility of the micro-nano copper particles.

[0009] In the preferred technical scheme of the preparation method of the above-mentioned micro-nano copper particles, in step S1, the silver seed is nanosilver particles or nanosilver ethanol solution, and the particle size of the nanosilver particles ranges from 5nm to 30nm; and / or, in step S1, the coating agent is a combination of one or more of polyvinyl pyrrolidone, hexadecyltrimethylammonium bromide, gelatin, and tannic acid; and / or, in step S1, the reducing agent is a combination of one or more of sodium borohydride, ascorbic acid, hydrazine hydrate, ferrous sulfate, sodium hypophosphite, and glucose; and / or, in step S1, the alcohol solution is a combination of one or more of ethylene glycol, diethylene glycol, propylene glycol, and polyethylene glycol.

[0010] In the case of adopting the above technical solution, using small-sized nano silver particles with a particle size of 5nm to 30nm to prepare silver seeds can reduce the preparation cost and facilitate production. In addition, the coating agent can have a coating effect on the surface of the copper particles, prevent agglomeration between the particles, and improve the dispersibility of the micro-nano copper particles. The reducing agent is used to reduce the copper ions into copper atoms so as to nucleate and grow into copper particles on the nano silver. Using an alcohol solution as a reaction solution can reduce the content of dissolved oxygen in the solution, and can prevent the copper particles from being oxidized during the reaction process, thereby preventing the copper particles from being oxidized and deteriorating.

[0011] In the preferred technical scheme of the preparation method of the above-mentioned micro-nano copper particles, in step S1, the molar concentration of nanosilver in the solution A is 0.05mmol / L~5mmol / L; and / or, in step S1, the molar concentration of the coating agent in the solution A is in the range of 0.05mol / L~0.75mol / L; and / or, in step S1, the molar concentration of the reducing agent in the solution A is in the range of 0.1mol / L~1.0mol / L.

[0012] In the case of adopting the above technical scheme, copper particles with a particle size range of 150nm to 700nm can be obtained by controlling the molar concentration of nanosilver in solution A to 0.05mmol / L to 5mmol / L. Specifically, the particle size of the copper particles can be controlled by controlling the concentration of nanosilver. When the particle size of the copper particles needs to be larger, the concentration of nanosilver is reduced to reduce the nucleation sites of copper atoms in the reaction solution, so that the particle size of the generated copper particles can be large; when small-sized copper particles need to be obtained, the concentration of nanosilver is increased to increase the nucleation sites of copper atoms in the reaction solution, so that the particle size of the generated copper particles can be small. Therefore, the preparation method of the present invention can more easily regulate the particle size of micro-nano copper particles, so as to obtain micro-nano copper particles in a required specific particle size range.

[0013] In addition, by controlling the molar concentration of the coating agent in solution A to 0.05 mol / L to 0.75 mol / L, copper particles with good oxidation resistance and surface properties can be obtained; specifically, the coating agent can have a coating effect on the surface of the copper particles, prevent agglomeration between the particles, and improve the dispersibility of the micro-nano copper particles. If the coating layer is too thin, the oxidation resistance of the copper particles will be affected, and if the coating layer is too thick, the performance of the copper particles will be affected. By adjusting the concentration of the coating agent, the morphology of the generated copper particles and the thickness of the coating layer on the surface of the copper particles can be controlled to obtain copper particles with good oxidation resistance and good surface properties.

[0014] In the preferred technical scheme of the above-mentioned method for preparing micro-nano copper particles, in step S2, the copper source is a combination of one or more of copper sulfate, copper nitrate, copper chloride, copper acetate and copper hydroxide; and / or, in step S2, the molar concentration of the copper source in the solution B is 0.01 mol / L to 0.5 mol / L.

[0015] In the preferred technical scheme of the above-mentioned method for preparing micro-nano copper particles, in step S3, solution B needs to be completely added to solution A within a preset time, and the preset time is no more than 5 minutes; and / or, in step S3, during the reaction process, the reaction solution is heated by an oil bath and continuously stirred, and the stirring speed ranges from 300r / min to 800r / min; and / or, in step S3, the set time ranges from 30min to 120min.

[0016] In the preferred technical solution of the above-mentioned method for preparing micro-nano copper particles, in step S4, before centrifuging the micro-nano copper solution, flocculant and ethanol are first added to the micro-nano copper solution.

[0017] When the above technical solution is adopted, the addition of flocculants and ethanol is conducive to the centrifugation of micro-nano copper particles from the solution, which is convenient for subsequent collection.

[0018] In the preferred technical scheme of the preparation method of the above-mentioned micro-nano copper particles, the flocculant is a combination of one or more of acetone, isopropanol, citric acid, sodium citrate, and sodium nitrate; and / or, the amount of the flocculant is 10% to 100% of the mass of the micro-nano copper.

[0019] In the preferred technical scheme of the above-mentioned method for preparing micro-nano copper particles, in step S4, the number of centrifugation is 3 to 10 times, and the centrifugal speed is 1000 r / min to 10000 r / min; and / or, in step S4, vacuum drying equipment is used for drying, the drying temperature is 45°C to 80°C, and the drying time is 1h to 24h.

[0020] When the above technical solution is adopted, the number of centrifugation and the centrifugal speed are related to the particle size of the copper particles. When the particle size of the copper particles is large, a small number of centrifugation times are required by using a low speed centrifugation; when the particle size of the copper particles is small, a high speed centrifugation is used, which requires more centrifugation times. In addition, vacuum drying can prevent the copper particles from being oxidized and deteriorated by contact with oxygen during the drying process, effectively ensuring the performance of the copper particles.

[0021] In a second aspect, the present invention provides a micro-nano copper particle, wherein the micro-nano copper particle is prepared by the above-mentioned method for preparing the micro-nano copper particle.

[0022] In the preferred technical solution of the above micro-nano copper particles, the particle size of the micro-nano copper particles ranges from 150 nm to 700 nm, and the mass proportion of silver in the micro-nano copper particles is less than 1%.

[0023] The particle size of the micro-nano copper particles is controlled at 150nm to 700nm. The micro-nano copper particles of this size have moderate surface energy, stable performance, are not prone to oxidation and agglomeration, and can maintain good activity, ensure performance, and are easy to use. In addition, the silver content in the copper particles is less than 1%, and the preparation cost is low.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] First, the micro-nano copper particles prepared by the preparation method of the present invention have excellent dispersibility, and in the preparation process, small-sized nano-silver particles are used as nucleation sites of copper atoms. Under the reduction effect of a reducing agent, the copper atoms nucleate on the nano-silver particles to obtain micro-nano copper particles. The particle size of the obtained micro-nano copper particles and the dispersibility of the micro-nano copper particles can be controlled by controlling the concentration of nano-silver, the concentration of a coating agent, the concentration of a reducing agent, and the concentration of a copper source, so as to obtain micro-nano copper particles with a particle size range of 150nm to 700nm, which not only avoids the problems of easy oxidation and easy agglomeration of small-sized nano-copper particles, but also has higher particle activity; and the preparation of the micro-nano copper particles is controllable and more convenient for application.

[0026] Secondly, the present invention uses small-sized nano-silver as nucleation sites, and the silver content in the copper particles produced is less than 1%, and the cost is low.

[0027] Third, the preparation method of the present invention does not need to be carried out in a protective gas environment, the preparation process is simple, and the principle of the preparation method is simple, which is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0029] Figure 1 is a flow chart of the preparation method of the present invention;

[0030] Figure 2 is a scanning electron microscope image of the nano silver particles prepared in the embodiment of the present invention;

[0031] Figure 3 is a scanning electron microscope image of the micro-nano copper particles prepared in Example 1 of the present invention;

[0032] Figure 4 is a scanning electron microscope image of the micro-nano copper particles prepared in Example 2 of the present invention;

[0033] Figure 5 is a scanning electron microscope image of the micro-nano copper particles prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0035] Specifically, Figure 1 As shown, the method for preparing micro-nano copper particles of the present invention comprises the following steps:

[0036] S1: Dissolve the silver seed, coating agent and reducing agent in an alcohol solution, stir evenly to obtain solution A, and heat solution A in an oil bath to a reaction temperature. The reaction temperature is the optimal temperature for the reducing agent to act. For example, when the reducing agent is sodium hypophosphite monohydrate, the reaction temperature is 160°C; when the reducing agent is ascorbic acid, the reaction temperature is 140°C.

[0037] S2: Dissolve the copper source in deionized water to obtain solution B.

[0038] S3: adding solution B to solution A, and then continuing the reaction for a set time to obtain a micro-nano copper solution. During the reaction, the reaction solution is continuously stirred, and heated by an oil bath and maintained at the reaction temperature.

[0039] S4: centrifuging the micro-nano copper solution obtained in step S3, and drying the particles obtained by centrifugation to obtain micro-nano copper particles.

[0040] The preparation method of the micro-nano copper particles of the present invention comprises adding silver crystal seeds to the reaction solution, the silver crystal seeds provide nucleus sites for copper ions to be reduced to copper atoms, and the reduced copper atoms nucleate on the silver crystal seeds, which can avoid the spontaneous nucleation of copper atoms and the uncontrollability of the spontaneous nucleation of copper particles, thereby improving the uniformity of the particle size of the copper particles. In addition, the dispersibility of the copper particles can be improved to avoid the agglomeration of the copper particles; and the particle size of the copper particles can be conveniently controlled by controlling the concentration of nano silver and the concentration of the copper source, so that copper particles within the required particle size range can be obtained, and the preparation process is simple. In addition, the use of an alcohol solution as the reaction solution can reduce the content of dissolved oxygen in the reaction solution, thereby avoiding the oxidation of the copper particles during the reaction process, and ensuring the purity of the copper particles and the performance in the subsequent application process.

[0041] During the reaction, the copper source can provide copper ions, the reducing agent can reduce the copper ions into copper atoms, and the copper atoms nucleate on the surface of the silver seeds (nanosilver particles) and grow into copper particles. The coating agent can coat the surface of the copper particles, thereby forming a coating film on the surface of the copper particles to prevent agglomeration between the copper particles and protect the copper particles from oxidation.

[0042] Preferably, in step S1, the silver seed crystals are nanosilver particles or nanosilver ethanol solution, and the particle size of the nanosilver particles ranges from 5 nm to 30 nm.

[0043] Using small-sized nanosilver particles with a particle size of 5nm to 30nm as seeds can reduce the mass proportion of silver in copper particles, reduce preparation costs, and facilitate production.

[0044] In practical applications, nanosilver particles can be purchased or prepared by themselves through a liquid phase reduction method.

[0045] Preferably, in step S1, the molar concentration of nanosilver in solution A is 0.05 mmol / L to 5 mmol / L. By controlling the molar concentration of nanosilver in solution A to 0.05 mmol / L to 5 mmol / L, copper particles with a particle size range of 150 nm to 700 nm can be obtained.

[0046] In the preparation method of the present invention, the particle size of the copper particles can be controlled by regulating the concentration of nanosilver. Under the condition of the same concentration of the copper source, the lower the concentration of nanosilver, the fewer the copper atom nucleation sites in the reaction solution, and the larger the particle size of the generated copper particles. The higher the concentration of nanosilver, the more the copper atom nucleation sites in the reaction solution, and the smaller the particle size of the generated copper particles. Therefore, the introduction of nanosilver as the copper atom nucleation site in the preparation method of the present invention can not only make the particle size of the copper particles uniform, but also make it more convenient to control the particle size of the copper particles by regulating the concentration of nanosilver, so as to obtain micro-nano copper particles within the required particle size range, so that the preparation process of the micro-nano copper particles is controllable, thereby reducing the difficulty of preparing micro-nano copper particles with uniform particle size and specific particle size, and making it more convenient to use.

[0047] Preferably, in step S1, the coating agent is a combination of one or more of polyvinyl pyrrolidone, hexadecyl trimethyl ammonium bromide, gelatin, and tannic acid. The coating agent can coat the surface of the copper particles, prevent agglomeration between the copper particles, improve the dispersibility of the copper particles, and avoid oxidation of the copper particles, thereby improving the oxidation resistance of the copper particles.

[0048] Preferably, in step S1, the molar concentration of the coating agent in solution A is in the range of 0.05 mol / L to 0.75 mol / L. The molar concentration of the coating agent in solution A is controlled to be in the range of 0.05 mol / L to 0.75 mol / L, and the coating film formed by the coating agent has a moderate thickness, so that copper particles with high oxidation resistance, good dispersibility and good surface properties can be obtained.

[0049] In the preparation method of the present invention, the morphology of the generated copper particles and the thickness of the coating layer on the surface of the copper particles can be controlled by adjusting the concentration of the coating agent. If the coating layer is too thin, the antioxidant ability of the copper particles will be affected, and if the coating layer is too thick, the performance of the copper particles will be affected, so as to obtain copper particles with good performance.

[0050] Preferably, in step S1, the reducing agent is a combination of one or more of sodium borohydride, ascorbic acid, hydrazine hydrate, ferrous sulfate, sodium hypophosphite, and glucose. The reducing agent is used to reduce copper ions to copper atoms so that the copper atoms nucleate on the nanosilver and grow into copper particles.

[0051] Preferably, in step S1, the molar concentration of the reducing agent in solution A is in the range of 0.1 mol / L to 1.0 mol / L. By controlling the molar concentration of the reducing agent in solution A to 0.1 mol / L to 1.0 mol / L and adjusting the concentration of the copper source, copper particles with a particle size range of 150 nm to 700 nm can be obtained, which is more convenient for application.

[0052] In the preparation method of the present invention, the particle size of the copper particles can be controlled by adjusting the concentration of the reducing agent, in combination with adjusting the concentration of the copper source and the concentration of the nanosilver, so that the preparation process of the copper particles is easier to control.

[0053] Preferably, in step S1, the alcohol solution is a combination of one or more of ethylene glycol, diethylene glycol, propylene glycol, and polyethylene glycol. Using an alcohol solution as a reaction solution can reduce the content of dissolved oxygen in the solution, avoid oxidation of copper particles during the reaction, and ensure the performance of micro-nano copper particles.

[0054] Preferably, in step S2, the copper source is a combination of one or more of copper sulfate, copper nitrate, copper chloride, copper acetate and copper hydroxide. The copper source provides copper ions for the reaction.

[0055] Preferably, in step S2, the molar concentration of the copper source in solution B is 0.01 mol / L to 0.5 mol / L.

[0056] In the preparation method of the present invention, the particle size of the copper particles can be controlled by controlling the concentration of the copper source, and adjusting the concentration of the reducing agent and the concentration of the nano-silver, so that the particle size of the micro-nano copper particles is controllable and the difficulty of preparation is reduced.

[0057] Preferably, in step S3, solution B needs to be completely added to solution A within a preset time, and the preset time is no more than 5 minutes.

[0058] When adding solution B to solution A, adding at a faster speed reduces the adding time and ensures that the growth rates of the copper particles are similar. This can avoid inconsistent particle sizes of the generated copper particles, keep the particle size of the copper particles uniform, and reduce the particle size difference between different copper particles.

[0059] Preferably, in step S3, the setting time ranges from 30 minutes to 120 minutes.

[0060] The time is set to be controlled within 30 minutes to 120 minutes, providing sufficient reaction time so that the copper atoms have enough time to nucleate and grow, and also facilitating the thorough reaction of the copper ions.

[0061] Preferably, in step S3, during the reaction process, the reaction solution is continuously stirred, and the stirring speed ranges from 300 r / min to 800 r / min.

[0062] During the reaction, the reaction solution is continuously stirred to evenly distribute the copper ions in the reaction solution, so that the particle size of each copper particle can evenly increase, the particle size of the obtained copper particles remains uniform, and the particle size difference between different copper particles is reduced.

[0063] Preferably, in step S4, before centrifuging the micro-nano copper solution, flocculants and ethanol are added to the micro-nano copper solution. Adding flocculants and ethanol to the micro-nano copper solution is conducive to centrifuging the micro-nano copper particles from the solution and facilitating collection.

[0064] Preferably, the flocculant is a combination of one or more of acetone, isopropanol, citric acid, sodium citrate and sodium nitrate.

[0065] Preferably, the amount of the flocculant used is 10% to 100% of the mass of the micro-nano copper.

[0066] The dosage of the flocculant is set to 10% to 100% of the mass of the micro-nano copper, which can not only enable the micro-nano copper particles to be smoothly centrifuged and collected, but also avoid the appearance of impurities in the collected micro-nano copper particles, thereby ensuring the purity of the micro-nano copper particles.

[0067] Preferably, in step S4, the number of centrifugation is 3 to 10 times, and the centrifugal speed is 1000 r / min to 10000 r / min.

[0068] The number of centrifugation times and the centrifugal speed are related to the particle size of the copper particles. When the particle size of the copper particles is large, a low speed centrifugation is used and a small number of centrifugation times are sufficient; when the particle size of the copper particles is small, a high speed centrifugation is used and a large number of centrifugation times are required.

[0069] Preferably, in step S4, vacuum drying equipment is used for drying, the drying temperature is 45° C. to 80° C., and the drying time is 1 h to 24 h.

[0070] Drying the nano copper particles by vacuum drying equipment can prevent the copper particles from oxidizing and deteriorating during the drying process, thereby ensuring the performance of the copper particles.

[0071] In addition, the present invention also protects a micro-nano copper particle, which is prepared by the above-mentioned preparation method of the micro-nano copper particle.

[0072] The micro-nano copper particles prepared by the preparation method of the present invention have uniform and controllable particle sizes and good dispersibility.

[0073] Preferably, the particle size of the micro-nano copper particles ranges from 150 nm to 700 nm, and the mass proportion of silver in the micro-nano copper particles is less than 1%.

[0074] The particle size of the micro-nano copper particles is controlled at 150nm to 700nm. The micro-nano copper particles of this size have moderate surface energy, stable performance, are not prone to oxidation and agglomeration, and can maintain good activity, ensure performance, and are easy to use. In addition, the silver content in the copper particles is less than 1%, and the preparation cost is low.

[0075] Example 1 :

[0076] A micro-nano copper particle is prepared by the following preparation steps:

[0077] S1: Prepare nanosilver particles with a particle size of about 13nm by liquid phase reduction method, and dissolve the prepared nanosilver particles in 50ml ethanol solution to prepare a 1.5mmol / L nanosilver solution to obtain silver seeds. The electron microscope scanning image of the prepared nanosilver particles is as follows: Figure 2 shown.

[0078] S2: Dissolve the nanosilver solution, 15 g polyvinyl pyrrolidone and 20 g sodium hypophosphite monohydrate in 100 ml polyethylene glycol solution, and stir evenly at a speed of 800 r / min to obtain solution A; heat solution A to 160° C. in an oil bath.

[0079] S3: Dissolve 2.5 g of copper sulfate in 50 ml of deionized water and stir well to obtain solution B.

[0080] S4: adding solution B into solution A at a dropping speed of 10 ml / min through a peristaltic pump, completing the dropping within 5 minutes, and then continuing the reaction for 60 minutes to obtain a micro-nano copper solution; during the reaction, the reaction solution is continuously stirred at a speed of 800 r / min, and the reaction solution is heated by an oil bath and maintained at 160°C.

[0081] S5: adding 200 ml of acetone-ethanol mixed solution to the micro-nano copper solution obtained in step S4, centrifuging at a speed of 8000 r / min for a total of 8 times, and after the last centrifugation, pouring out the supernatant; placing the bottom copper particles in a vacuum drying oven, vacuum drying at 50° C. for 6 hours to obtain dry micro-nano copper particles.

[0082] The scanning electron microscope image of the micro-nano copper particles prepared in this embodiment is as follows: Figure 3 As shown, the particle size of the micro-nano copper particles is about 200 nm, the particles have high dispersibility and uniform particle size, and the silver content in the micro-nano copper particles is 0.8%, with low cost.

[0083] Example 2 :

[0084] A micro-nano copper particle is prepared by the following preparation steps:

[0085] S1: Prepare nanosilver particles with a particle size of about 13nm by liquid phase reduction method, and dissolve the prepared nanosilver particles in 50ml ethanol solution to prepare a 1mmol / L nanosilver solution to obtain silver seeds. The electron microscope scanning image of the prepared nanosilver particles is as follows: Figure 2 shown.

[0086] S2: Dissolve the nanosilver solution, 30 g of hexadecyltrimethylammonium bromide and 10 g of ascorbic acid in 100 ml of ethylene glycol solution, and stir evenly at a speed of 800 r / min to obtain solution A; heat solution A to 140° C. in an oil bath.

[0087] S3: Dissolve 2.1 g of copper chloride in 50 ml of deionized water and stir well to obtain solution B.

[0088] S4: adding solution B into solution A at a dropping speed of 10 ml / min through a peristaltic pump, completing the dropping within 5 minutes, and then continuing the reaction for 60 minutes to obtain a micro-nano copper solution; during the reaction, the reaction solution is continuously stirred at a speed of 800 r / min, and the reaction solution is heated by an oil bath and maintained at 140°C.

[0089] S5: adding 200 ml of sodium nitrate-ethanol mixed solution to the micro-nano copper solution obtained in step S4, centrifuging at a speed of 6000 r / min for a total of 5 times, and after the last centrifugation, pouring out the supernatant; placing the bottom copper particles in a vacuum drying oven, vacuum drying at 50° C. for 4 hours to obtain dry micro-nano copper particles.

[0090] The scanning electron microscope image of the micro-nano copper particles prepared in this embodiment is as follows: Figure 4 As shown, the particle size of the micro-nano copper particles is about 350 nm, the particles have high dispersibility and uniform particle size, and the silver content in the micro-nano copper particles is 0.5%, with low cost.

[0091] Example 3 :

[0092] A micro-nano copper particle is prepared by the following preparation steps:

[0093] S1: Prepare nanosilver particles with a particle size of about 13nm by liquid phase reduction method, and dissolve the prepared nanosilver particles in 50ml ethanol solution to prepare a 0.75mmol / L nanosilver solution to obtain silver seeds. The electron microscope scanning image of the prepared nanosilver particles is as follows: Figure 2 shown.

[0094] S2: Dissolve the nanosilver solution, 18 g tannic acid and 4 g glucose in 100 ml diethylene glycol solution, and stir evenly at a speed of 800 r / min to obtain solution A; heat solution A to 100° C. in an oil bath.

[0095] S3: Dissolve 3.1 g of copper acetate in 50 ml of deionized water and stir well to obtain solution B.

[0096] S4: adding solution B into solution A at a dropping speed of 10 ml / min through a peristaltic pump, completing the dropping within 5 minutes, and then continuing the reaction for 60 minutes to obtain a micro-nano copper solution; during the reaction, the reaction solution is continuously stirred at a speed of 800 r / min, and the reaction solution is heated by an oil bath and maintained at 100°C.

[0097] S5: adding 200 ml of ammonium citrate-ethanol mixed solution to the micro-nano copper solution obtained in step S4, centrifuging at a speed of 4000 r / min for a total of 3 times, and after the last centrifugation, pouring out the supernatant; placing the bottom copper particles in a vacuum drying oven, vacuum drying at 50° C. for 2 h to obtain dry micro-nano copper particles.

[0098] The scanning electron microscope image of the micro-nano copper particles prepared in this embodiment is as follows: Figure 5 As shown, the particle size of the micro-nano copper particles is about 500 nm, the particles have high dispersibility and uniform particle size, the silver content in the micro-nano copper particles is 0.4%, and the cost is low.

[0099] Depend on Figures 3 to 5 It can be seen that the particle size distribution of the micro-nano copper particles prepared by the preparation method of the present invention is uniform, and the particle size of the micro-nano copper particles can be accurately controlled. In addition, the prepared micro-nano copper particles have good dispersibility and do not agglomerate.

[0100] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for preparing micro-nano copper particles, characterized in that: The preparation method comprises the following steps: S1: dissolving silver seed crystals, a coating agent and a reducing agent in an alcohol solution, stirring uniformly to obtain a solution A, and heating the solution A in an oil bath; S2: dissolving the copper source in deionized water to obtain solution B; S3, adding solution B into solution A, and then continuing the reaction for a set time to obtain a micro-nano copper solution; S4, centrifuging the micro-nano copper solution obtained in step S3, and drying the particles obtained by centrifugation to obtain micro-nano copper particles.

2. The method for preparing micro-nano copper particles according to claim 1, characterized in that: In step S1, the silver seed is nanosilver particles or nanosilver ethanol solution, and the particle size of the nanosilver particles ranges from 5 nm to 30 nm; And / or, in step S1, the coating agent is a combination of one or more of polyvinyl pyrrolidone, hexadecyltrimethylammonium bromide, gelatin, and tannic acid; And / or, in step S1, the reducing agent is a combination of one or more of sodium borohydride, ascorbic acid, hydrazine hydrate, ferrous sulfate, sodium hypophosphite, and glucose; And / or, in step S1, the alcohol solution is a combination of one or more of ethylene glycol, diethylene glycol, propylene glycol, and polyethylene glycol.

3. The method for preparing micro-nano copper particles according to claim 2, characterized in that: In step S1, the molar concentration of nanosilver in the solution A is 0.05 mmol / L to 5 mmol / L; and / or, in step S1, the molar concentration of the coating agent in the solution A is in the range of 0.05 mol / L to 0.75 mol / L; And / or, in step S1, the molar concentration of the reducing agent in the solution A is in the range of 0.1 mol / L to 1.0 mol / L.

4. The method for preparing micro-nano copper particles according to claim 1, characterized in that: In step S2, the copper source is a combination of one or more of copper sulfate, copper nitrate, copper chloride, copper acetate and copper hydroxide; And / or, in step S2, the molar concentration of the copper source in the solution B is in the range of 0.01 mol / L to 0.5 mol / L.

5. The method for preparing micro-nano copper particles according to claim 1, characterized in that: In step S3, solution B needs to be completely added to solution A within a preset time, and the preset time is no more than 5 minutes; And / or, in step S3, during the reaction process, the reaction solution is heated by an oil bath and continuously stirred, and the stirring speed ranges from 300 r / min to 800 r / min; And / or, in step S3, the set time ranges from 30 minutes to 120 minutes.

6. The method for preparing micro-nano copper particles according to claim 1, characterized in that: In step S4, before centrifuging the micro-nano copper solution, flocculant and ethanol are added into the micro-nano copper solution.

7. The method for preparing micro-nano copper particles according to claim 6, characterized in that: The flocculant is a combination of one or more of acetone, isopropanol, citric acid, sodium citrate, and sodium nitrate; And / or, the amount of the flocculant used is 10% to 100% of the mass of the micro-nano copper.

8. The method for preparing micro-nano copper particles according to claim 1, characterized in that: In step S4, the number of centrifugation is 3 to 10 times, and the centrifugal speed is 1000 r / min to 10000 r / min; And / or, in step S4, a vacuum drying device is used for drying, the drying temperature is 45° C. to 80° C., and the drying time is 1 h to 24 h.

9. A micro-nano copper particle, characterized in that: The micro-nano copper particles are prepared by the method for preparing micro-nano copper particles according to any one of claims 1 to 8.

10. The micro-nano copper particles according to claim 9, characterized in that: The particle size of the micro-nano copper particles ranges from 150 nm to 700 nm, and the mass proportion of silver in the micro-nano copper particles is less than 1%.

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