Preparation method of spherical copper powder and spherical copper powder

Abstract

This invention provides a method for preparing spherical copper powder and the spherical copper powder itself, specifically relating to the field of metal materials technology. The preparation method includes first preparing a solution of soluble copper salt, then adding a dispersant and stirring until homogeneous to obtain a copper salt dispersion; then adding a first reducing agent solution to the copper salt dispersion for a first reaction of 0.5-1.5 h, followed by adding a second reducing agent solution and continuing the second reaction for 0.5-1 h to obtain crude spherical copper powder; finally, washing the crude spherical copper powder, adding a coating agent for dispersion and coating, and drying to obtain the spherical copper powder. This preparation method uses a two-step reduction process to control the rate of the reduction reaction, preventing copper aggregation caused by the simultaneous generation of large amounts of copper, thus reducing the particle size of the copper powder; moreover, the presence of the dispersant also prevents copper powder aggregation, further reducing the particle size of the copper powder. This preparation method is simple, easy to mass-produce, and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, and in particular to a method for preparing spherical copper powder and the spherical copper powder itself. Background Technology

[0002] With the rapid development of the electronics and information industry, precious metal electronic pastes have become one of the key materials for producing various electronic components. Currently, silver powder is the most widely used and consumed material. However, compared to silver, copper powder has excellent electrical conductivity similar to silver (silver's volume resistivity is 1.59 × 10⁻⁶). -6 The volume resistivity of copper is 1.72 × 10⁻⁶ Ω·cm. -6 With a density of Ω·cm, and a price only 1 / 20th that of silver, copper can replace ultrafine silver powder, gold powder, and other precious metal materials. It is widely used in conductive pastes, conductive adhesives, and other electrical fields, and is also applicable to aerospace technology, microelectronics, chemistry, biology, and medicine. Using copper powder to replace silver powder has significant economic benefits and is one of the future development directions for electronic pastes.

[0003] In the electronics and electrical industries, for conductive metal materials, powders with good dispersibility, high sphericity, good oxidation resistance, and narrow particle size distribution are mainly selected to give the slurry good rheological properties, electrical conductivity, and sintering performance. However, copper powder prepared by existing physical methods suffers from low sphericity, large shape differences, poor uniformity, and complex processes.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for preparing spherical copper powder, so as to alleviate the technical problems of low sphericity, large shape differences, poor uniformity, and complex processes of copper powder prepared by physical methods in the prior art.

[0006] The second objective of this invention is to provide a spherical copper powder.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] The first aspect of this invention provides a method for preparing spherical copper powder, comprising the following steps:

[0009] A. Prepare a solution of soluble copper salt, add a dispersant, and stir until homogeneous to obtain a copper salt dispersion.

[0010] B. After adding the first reducing agent solution to the copper salt dispersion and carrying out the first reaction for 0.5h-1.5h, add the second reducing agent solution and continue the second reaction for 0.5h-1h to obtain spherical crude copper powder.

[0011] C. After cleaning the crude spherical copper powder, add a coating agent to disperse and coat it, and then dry it to obtain the spherical copper powder.

[0012] Furthermore, the concentration of the copper salt dispersion is 0.1 kg / L-0.8 kg / L, preferably 0.2 kg / L-0.5 kg / L.

[0013] Preferably, the concentration of the first reducing agent solution is 0.1 kg / L-0.35 kg / L, and more preferably 0.13 kg / L-0.18 kg / L.

[0014] Preferably, the concentration of the second reducing agent solution is 0.03 kg / L to 0.15 kg / L.

[0015] Furthermore, the mass of the first reducing agent is 20%-100% of the mass of the copper salt.

[0016] Preferably, the mass of the second reducing agent is 5%-20% of the mass of the copper salt.

[0017] Furthermore, the first reducing agent or the second reducing agent is independently selected from at least one of formaldehyde, glucose, ascorbic acid, sodium sulfite, hydrazine hydrate and hydroxylamine sulfate.

[0018] Furthermore, the pH of the first reducing agent solution or the second reducing agent solution is 11-13.

[0019] Preferably, the temperature of the first reaction or the second reaction is 50°C-90°C.

[0020] Preferably, a pH adjuster is added to adjust the pH of the first reducing agent solution or the second reducing agent solution.

[0021] Preferably, the pH adjuster includes at least one of ammonia, sodium hydroxide, and sodium carbonate.

[0022] Furthermore, the soluble copper salt is a divalent soluble copper salt.

[0023] Preferably, the divalent soluble copper salt includes at least one of copper sulfate, copper nitrate, copper chloride, copper acetate, copper lactate, copper oleate, copper citrate, and copper tartrate.

[0024] Furthermore, the dispersant includes at least one of gelatin, gum arabic, polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol.

[0025] Furthermore, the amount of the dispersant used is 0.5%-1% of the mass of the soluble copper salt.

[0026] Further, in step C, the encapsulating agent includes at least one of stearic acid, erucic acid, oleic acid, hexadecanoic acid, and tetradecanoic acid, preferably stearic acid and / or oleic acid.

[0027] Preferably, the amount of the encapsulating agent is 0.1%-1.0% of the crude mass of the spherical copper powder.

[0028] The second aspect of the present invention provides spherical copper powder prepared by the preparation method described in the first aspect.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] The present invention provides a method for preparing spherical copper powder using a liquid-phase reduction method. Soluble copper salts are used as raw materials, mixed with a dispersant, and then subjected to a two-step reduction, washing, anti-oxidation coating treatment, and drying to obtain spherical copper powder. The two-step reduction controls the rate of the reduction reaction, preventing copper aggregation caused by the simultaneous generation of large amounts of copper, thus reducing the particle size of the copper powder. Furthermore, the presence of the dispersant also prevents copper powder aggregation, further reducing the particle size. This preparation method is simple, highly controllable, easy to mass-produce, and suitable for large-scale industrial production.

[0031] The spherical copper powder provided by this invention has a particle size distribution between 0.5μm and 5μm, with uniform particle size, high sphericity, and low oxygen content. This spherical copper powder provides a higher-performance and lower-cost raw material for electronic pastes, promoting the development of downstream industries. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 Here is a scanning electron microscope image of the spherical copper powder obtained in Example 1;

[0034] Figure 2 Here is a scanning electron microscope image of the spherical copper powder obtained in Example 2;

[0035] Figure 3 The image shows a scanning electron microscope (SEM) image of the spherical copper powder obtained in Comparative Example 1.

[0036] Figure 4 This is a scanning electron microscope image of the spherical copper powder obtained in Comparative Example 4. Detailed Implementation

[0037] The embodiments and examples of the present invention will be described in detail below with reference to the implementation methods and examples. However, those skilled in the art will understand that the following implementation methods and examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The first aspect of this invention provides a method for preparing spherical copper powder, comprising the following steps:

[0039] A. Prepare a solution of soluble copper salt, add a dispersant, and stir until homogeneous to obtain a copper salt dispersion.

[0040] B. After adding the first reducing agent solution to the copper salt dispersion and allowing the first reaction to proceed for 0.5h-1.5h, add the second reducing agent solution and continue the second reaction for 0.5h-1h to obtain crude spherical copper powder.

[0041] C. After cleaning the crude spherical copper powder, add a coating agent to disperse and coat it, and then dry it to obtain the spherical copper powder.

[0042] The present invention provides a method for preparing spherical copper powder using a liquid-phase reduction method. Soluble copper salts are used as raw materials, mixed with a dispersant, and then subjected to a two-step reduction, washing, anti-oxidation coating treatment, and drying to obtain spherical copper powder. The two-step reduction controls the rate of the reduction reaction, preventing copper aggregation caused by the simultaneous generation of large amounts of copper, thus reducing the particle size of the copper powder. Furthermore, the presence of the dispersant also prevents copper powder aggregation, further reducing the particle size. This preparation method is simple, highly controllable, easy to mass-produce, and suitable for large-scale industrial production.

[0043] When the first reaction time is less than 0.5 hours, the reaction is incomplete, the copper powder does not grow fully, and the copper powder particles are small in size and have poor sphericity. In some embodiments of the present invention, the first reaction time is typically, but not limited to, 0.5 hours, 0.75 hours, 1 hour, 1.25 hours, or 1.5 hours.

[0044] When the second reaction time is less than 0.5 h, the reaction is incomplete, the copper powder does not grow fully, and the copper powder particles are small in size and have poor sphericity. In some embodiments of the present invention, the second reaction time is typically, but not limited to, 0.5 h, 0.75 h, or 1 h.

[0045] Further, the concentration of the copper salt dispersion is 0.1 kg / L-0.8 kg / L, preferably 0.2 kg / L-0.5 kg / L. When the concentration of the copper salt dispersion is less than 0.1 kg / L, the concentration is too low, limiting the subsequent yield; when the concentration of the copper salt dispersion is greater than 0.8 kg / L, the concentration is too high, resulting in excessive copper powder generated in the region, causing copper powder agglomeration, powder adhesion, and poor morphology. When the concentration of the copper salt dispersion is between 0.2 kg / L and 0.5 kg / L, better yield and reaction efficiency can be obtained. In some embodiments of the present invention, the concentration of the copper salt dispersion is typically, but not limited to, 0.1 kg / L, 0.2 kg / L, 0.3 kg / L, 0.4 kg / L, 0.5 kg / L, 0.6 kg / L, 0.7 kg / L, or 0.8 kg / L.

[0046] Preferably, the concentration of the first reducing agent solution is 0.1 kg / L-0.35 kg / L, more preferably 0.13 kg / L-0.18 kg / L. When the concentration of the first reducing agent solution is below 0.1 kg / L, the reducing power provided is insufficient, the reaction is incomplete, the copper powder growth is incomplete, and the morphology is poor. When the concentration of the first reducing agent solution is above 0.35 kg / L, the reduction kinetics are too high, the reduction rate is fast, and the copper powder exhibits aggregation. In some embodiments of the present invention, the concentration of the first reducing agent solution is typically, but not limited to, 0.1 kg / L, 0.11 kg / L, 0.12 kg / L, 0.13 kg / L, 0.14 kg / L, 0.15 kg / L, 0.16 kg / L, 0.17 kg / L, 0.18 kg / L, 0.19 kg / L, 0.2 kg / L, 0.25 kg / L, 0.3 kg / L, or 0.35 kg / L.

[0047] Preferably, the concentration of the second reducing agent solution is 0.03 kg / L to 0.15 kg / L. When the concentration of the second reducing agent solution is below 0.03 kg / L, the reduction kinetics are insufficient, the reaction is incomplete, the copper powder growth is incomplete, and the morphology is poor. When the concentration of the second reducing agent solution is above 0.15 kg / L, the reduction kinetics are too high, the reduction rate is fast, and the copper powder exhibits aggregation. In some embodiments of the present invention, the concentration of the second reducing agent solution is typically, but not limited to, 0.03 kg / L, 0.04 kg / L, 0.05 kg / L, 0.06 kg / L, 0.07 kg / L, 0.08 kg / L, 0.10 kg / L, 0.13 kg / L, or 0.15 kg / L.

[0048] Further, the mass of the first reducing agent is 20%-100% of the mass of the copper salt. When the mass of the first reducing agent is less than 20% of the mass of the copper salt, the reducing agent is insufficient, and the reaction is incomplete; when the mass of the first reducing agent is greater than 100% of the mass of the copper salt, the reduction kinetics are too strong, the reaction rate is fast, and the copper powder agglomerates. In some embodiments of the present invention, the mass of the first reducing agent is typically, but not limited to, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the mass of the copper salt.

[0049] Preferably, the mass of the second reducing agent is 5%-20% of the mass of the copper salt. When the mass of the second reducing agent is less than 5% of the mass of the copper salt, the reducing agent is insufficient, and the reaction is incomplete; when the mass of the second reducing agent is greater than 20% of the mass of the copper salt, the reduction kinetics are too strong, the reaction rate is fast, and the copper powder agglomerates. In some embodiments of the present invention, the mass of the second reducing agent is typically, but not limited to, 5%, 7%, 9%, 11%, 13%, 15%, 17%, or 20% of the mass of the copper salt.

[0050] Furthermore, the first reducing agent or the second reducing agent is independently selected from at least one of formaldehyde, glucose, ascorbic acid, sodium sulfite, hydrazine hydrate and hydroxylamine sulfate.

[0051] Furthermore, the pH of the first or second reducing agent solution is 11-13. When the pH of the first or second reducing agent solution is 11-13, it provides better reaction conditions. A low pH will lead to insufficient reducing power and incomplete reaction. A high pH reduces the reducing power, resulting in a fast reaction rate and copper powder aggregation and adhesion.

[0052] Preferably, the temperature of the first or second reaction is 50°C-90°C. When the temperature of the first or second reaction is below 50°C, the power is insufficient, and the second reaction cannot proceed; when the temperature of the first or second reaction is above 90°C, energy consumption increases, preparation costs are high, and the reaction rate accelerates, easily causing copper powder to aggregate. In some embodiments of the present invention, the temperature of the first or second reaction is typically, but not limited to, 50°C, 60°C, 70°C, 80°C, or 90°C.

[0053] Preferably, a pH adjuster is added to adjust the pH of the first reducing agent solution or the second reducing agent solution.

[0054] Preferably, the pH adjuster includes at least one of ammonia, sodium hydroxide, and sodium carbonate.

[0055] Furthermore, the soluble copper salt is a divalent soluble copper salt.

[0056] Preferably, the divalent soluble copper salt includes at least one of copper sulfate, copper nitrate, copper chloride, copper acetate, copper lactate, copper oleate, copper citrate, and copper tartrate.

[0057] Furthermore, the dispersant includes at least one of gelatin, gum arabic, polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol.

[0058] Further, the amount of the dispersant is 0.5%-1% of the mass of the soluble copper salt. In some embodiments of the invention, the amount of dispersant is typically, but not limited to, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1% of the mass of the soluble copper salt.

[0059] Further, in step C, the encapsulating agent includes at least one of stearic acid, erucic acid, oleic acid, hexadecanoic acid, and tetradecanoic acid, preferably stearic acid and / or oleic acid.

[0060] Preferably, the amount of the encapsulating agent is 0.1%-1.0% of the crude mass of the spherical copper powder. The encapsulating agent prevents the copper powder from reacting with oxygen, thereby reducing the oxygen content of the spherical copper powder.

[0061] The second aspect of the present invention provides spherical copper powder prepared by the preparation method described in the first aspect.

[0062] The spherical copper powder provided by this invention has a particle size distribution between 0.5μm and 5μm, with uniform particle size, high sphericity, and low oxygen content. This spherical copper powder provides a higher-performance and lower-cost raw material for electronic pastes, promoting the development of downstream industries.

[0063] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0064] Example 1

[0065] This embodiment provides a spherical copper powder, and the preparation process is as follows:

[0066] 1. Weigh 10kg of copper nitrate into a mixing tank, add water to make 20L to dissolve, add the pre-dissolved latex solution containing 30g of gelatin, and finally add water to make 30L of copper salt dispersion. Adjust the temperature to 90℃.

[0067] 2. Weigh 5 kg of glucose into a mixing tank, add 20 L of water to dissolve it, add 5 kg of sodium hydroxide, and add water to prepare 30 L of the first reducing agent solution. Adjust the temperature to 90℃.

[0068] 3. Weigh 1 kg of hydrazine hydrate into a mixing tank, add 10 L of water to dissolve it, add 2 kg of sodium hydroxide, and add water to prepare a 20 L second reducing agent solution. Adjust the temperature to 90℃.

[0069] 4. First, add the first reducing agent solution to the copper salt dispersion and stir for 60 minutes. Then, add the second reducing agent solution and continue the reaction for 45 minutes, keeping the system temperature at 90℃ during the process.

[0070] 5. After the reaction is complete, wash the copper powder, add 30g of oleic acid for dispersion and coating, and dry to obtain spherical copper powder.

[0071] Example 2

[0072] This embodiment provides a spherical copper powder. The difference from Embodiment 1 is that polyvinylpyrrolidone is used instead of gelatin in step 1. The other raw materials and methods are the same as in Embodiment 1, and will not be repeated here.

[0073] Example 3

[0074] This embodiment provides a spherical copper powder. The difference from embodiment 2 is that the system temperature in step 4 is controlled at 50°C. The other raw materials and methods are the same as in embodiment 2, and will not be repeated here.

[0075] Example 4

[0076] This embodiment provides a spherical copper powder, and the preparation process is as follows:

[0077] 1. Weigh 10kg of copper chloride into a mixing tank, add water to 20L to dissolve, add the pre-dissolved latex solution containing 30g of gelatin, and finally add water to prepare a 100L copper salt dispersion. Adjust the temperature to 50℃.

[0078] 2. Weigh 10 kg of ascorbic acid into a mixing tank, add 20 L of water to dissolve it, add 10 kg of sodium hydroxide, and add water to prepare 100 L of the first reducing agent solution. Adjust the temperature to 50℃.

[0079] 3. Weigh 2 kg of hydrazine hydrate into a mixing tank, add 10 L of water to dissolve it, add 4 kg of sodium hydroxide, and add water to prepare a 33 L second reducing agent solution. Adjust the temperature to 50 °C.

[0080] 4. First, add the first reducing agent solution to the copper salt dispersion and stir for 60 minutes. Then, add the second reducing agent solution and continue the reaction for 45 minutes, keeping the system temperature at 50℃ during the process.

[0081] 5. After the reaction is complete, wash the copper powder, add 30g of oleic acid for dispersion and coating, and dry to obtain spherical copper powder.

[0082] Example 5

[0083] This embodiment provides a spherical copper powder, and the preparation process is as follows:

[0084] 1. Weigh 10kg of copper chloride into a mixing tank, add water to 8L to dissolve it, add the pre-dissolved latex solution containing 30g of gelatin, and finally add water to prepare a 12.5L copper salt dispersion. Adjust the temperature to 50℃.

[0085] 2. Weigh 10 kg of ascorbic acid into a mixing tank, add 20 L of water to dissolve it, add 10 kg of sodium hydroxide, and add water to prepare a 30 L first reducing agent solution. Adjust the temperature to 50 °C.

[0086] 3. Weigh 2 kg of hydrazine hydrate into a mixing tank, add 8 L of water to dissolve it, add 4 kg of sodium hydroxide, and add water to prepare a 13 L second reducing agent solution. Adjust the temperature to 50℃.

[0087] 4. First, add the first reducing agent solution to the copper salt dispersion and stir for 60 minutes. Then, add the second reducing agent solution and continue the reaction for 45 minutes, keeping the system temperature at 50℃ during the process.

[0088] 5. After the reaction is complete, wash the copper powder, add 30g of oleic acid for dispersion and coating, and dry to obtain spherical copper powder.

[0089] Example 6

[0090] This embodiment provides a spherical copper powder, and the preparation process is as follows:

[0091] 1. Weigh 10kg of copper nitrate into a mixing tank, add water to make 20L to dissolve, add the pre-dissolved latex solution containing 30g of gelatin, and finally add water to make 30L of copper salt dispersion. Adjust the temperature to 80℃.

[0092] 2. Weigh 5 kg of glucose into a mixing tank, add 20 L of water to dissolve it, add 5 kg of sodium hydroxide, and add water to prepare 30 L of the first reducing agent solution. Adjust the temperature to 80℃.

[0093] 3. Weigh 1 kg of hydrazine hydrate into a mixing tank, add 10 L of water to dissolve it, add 2 kg of sodium hydroxide, and add water to prepare a 20 L second reducing agent solution. Adjust the temperature to 80℃.

[0094] 4. First, add the first reducing agent solution to the copper salt dispersion and stir for 60 minutes. Then, add the second reducing agent solution and continue the reaction for 45 minutes, keeping the system temperature at 80℃ during the process.

[0095] 5. After the reaction is complete, wash the copper powder, add 30g of oleic acid for dispersion and coating, and dry to obtain spherical copper powder.

[0096] Example 7

[0097] This embodiment provides a spherical copper powder. The difference from Example 1 is that the reaction temperature is controlled at 70°C. The other raw materials and methods are the same as in Example 1, and will not be repeated here.

[0098] Example 8

[0099] This embodiment provides a spherical copper powder. The difference from Example 1 is that the reaction temperature is controlled at 60°C. The other raw materials and methods are the same as in Example 1, and will not be repeated here.

[0100] Comparative Example 1

[0101] This comparative example provides a copper powder. Unlike Example 1, in step 4, the first reducing agent solution and the second reducing agent solution are simultaneously added to the copper salt dispersion, and the mixture is stirred and reacted for 105 minutes, with the system temperature controlled at 50°C during the process. The remaining raw materials and methods are the same as in Example 1 and will not be repeated here.

[0102] Comparative Example 2

[0103] This comparative example provides a copper powder that differs from Example 1 in that step 3 is omitted. In step 4, the first reducing agent solution is added to the copper salt dispersion, and the mixture is stirred and reacted for 60 minutes, with the system temperature controlled at 50°C during the process. The remaining raw materials and methods are the same as in Example 1 and will not be repeated here.

[0104] Comparative Example 3

[0105] This comparative example provides a copper powder that differs from Example 1 in that step 2 is omitted. In step 4, the second reducing agent solution is added to the copper salt dispersion, and the mixture is stirred for 105 minutes, with the system temperature controlled at 90°C during the process. The remaining raw materials and methods are the same as in Example 1 and will not be repeated here.

[0106] Comparative Example 4

[0107] This comparative example provides a copper powder, which is a physically pulverized copper powder, obtained commercially. The particle size is 5μm.

[0108] Experimental Example 1

[0109] The particle size of the copper powders obtained in Examples 1-8 and Comparative Examples 1-4 was statistically analyzed, and the data are shown in Table 1 below.

[0110] Table 1 Test Data

[0111]

[0112] As can be seen from Table 1, the copper powder prepared by the method of the present invention has a narrower particle size distribution and better uniformity. Compared with the copper powder prepared by the physical method in Comparative Example 4 without post-treatment, the coated copper powder has better antioxidant properties.

[0113] Experimental Example 2

[0114] Scanning electron microscopy (SEM) was performed on the copper powders obtained in Examples 1, 2, 1, and 4. The corresponding SEM images are shown below. Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown.

[0115] pass Figure 1 , Figure 2 , Figure 3 and Figure 4 It can be seen that the sphericity of the copper powder obtained by the present invention is close to that of copper powder produced by physical method, and the uniformity of the particles is better than that of copper powder produced by physical method.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing spherical copper powder, characterized in that, Includes the following steps: A. Prepare a solution of soluble copper salt, add a dispersant, and stir until homogeneous to obtain a copper salt dispersion with a concentration of 0.1 kg / L-0.8 kg / L; The dispersant includes at least one selected from gelatin, gum arabic, polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol; the amount of the dispersant used is 0.5%-1% of the mass of the soluble copper salt. B. Add a first reducing agent solution with a concentration of 0.1 kg / L-0.35 kg / L and a pH of 11-13 to the copper salt dispersion and carry out the first reaction at 50℃-90℃ for 0.5 h-1.5 h. Then add a second reducing agent solution with a concentration of 0.03 kg / L-0.15 kg / L and a pH of 11-13 and continue the second reaction at 50℃-90℃ for 0.5 h-1 h to obtain spherical crude copper powder. The first reducing agent or the second reducing agent is independently selected from at least one of formaldehyde, glucose, ascorbic acid, sodium sulfite, hydrazine hydrate and hydroxylamine sulfate; The mass of the first reducing agent is 20%-100% of the mass of the copper salt; the mass of the second reducing agent is 5%-20% of the mass of the copper salt. C. After cleaning the crude spherical copper powder, add a coating agent to disperse and coat it, and then dry it to obtain the spherical copper powder.

2. The preparation method according to claim 1, characterized in that, The concentration of the copper salt dispersion is 0.2 kg / L to 0.5 kg / L.

3. The preparation method according to claim 1, characterized in that, The concentration of the first reducing agent solution is 0.13 kg / L to 0.18 kg / L.

4. The preparation method according to any one of claims 1-3, characterized in that, A pH adjuster is added to adjust the pH of either the first reducing agent solution or the second reducing agent solution.

5. The preparation method according to claim 4, characterized in that, The pH adjuster includes at least one of ammonia, sodium hydroxide, and sodium carbonate.

6. The preparation method according to any one of claims 1-3, characterized in that, The soluble copper salt is a divalent soluble copper salt.

7. The preparation method according to claim 6, characterized in that, The divalent soluble copper salt includes at least one of copper sulfate, copper nitrate, copper chloride, copper acetate, copper lactate, copper oleate, copper citrate, and copper tartrate.

8. The preparation method according to any one of claims 1-3, characterized in that, In step C, the encapsulating agent includes at least one of stearic acid, erucic acid, oleic acid, hexadecanoic acid, and tetradecanoic acid.

9. The preparation method according to any one of claims 1-3, characterized in that, In step C, the encapsulating agent is stearic acid and / or oleic acid.

10. The preparation method according to any one of claims 1-3, characterized in that, The amount of the encapsulating agent used is 0.1%-1.0% of the crude mass of the spherical copper powder.

11. A spherical copper powder prepared by the preparation method according to any one of claims 1-10.

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