Preparation method of quasi-spherical copper powder, quasi-spherical copper powder and application

Abstract

The present invention provides a preparation method, quasi-spherical copper powder and application thereof, and specifically relates to the technical field of metal powder preparation. The preparation method comprises the following steps: A. adding a copper salt solution and a reducing solution to a reaction base liquid under stirring to carry out a reaction; B. adding a coating agent solution after the reaction is completed to carry out coating, followed by solid-liquid separation, washing and filtration to obtain a paste copper powder; C. adding the paste copper powder to a modifier solution for surface modification, followed by filtration and drying to obtain the quasi-spherical copper powder. The preparation method of the quasi-spherical copper powder provided by the present invention does not require inert atmosphere protection, and obtains quasi-spherical copper powder with uniform particle size by regulating a mild reducing agent in the reaction base liquid and the reducing solution and a copper salt solution. By using the coating and surface modification processes simultaneously, the oxidation of the copper powder is controlled during the reaction, washing and storage processes, thereby improving the oxidation resistance of the copper powder.

Description

Technical Field

[0001] The present invention relates to the technical field of metal powder preparation, in particular to a preparation method of quasi-spherical copper powder, the quasi-spherical copper powder and applications. Background Art

[0002] With the rapid development of the electronic information industry, precious metal electronic paste has become one of the key materials for the production of various electronic components. Currently, the most widely used and largest amount of metal silver powder is used. However, compared with silver, copper powder has excellent conductivity similar to that of silver (the volume resistivity of silver is 1.59×10 6 Ω·cm, the volume resistivity of copper is 1.72×10 6 Ω·cm), and copper's price is only 1 / 20 of silver. It can be used to replace ultrafine silver powder, gold powder, and other precious metal materials. It is widely used in electrical fields such as conductive pastes and conductive adhesives. It is also suitable for aerospace technology, microelectronics, chemistry, biology, medicine, and other fields. Using copper powder to replace silver powder has huge economic benefits and is one of the future development directions of electronic pastes.

[0003] The methods for preparing copper powder in the existing technology include liquid phase reduction method, electrolysis method, atomization method, etc. Compared with the high energy consumption and environmental pollution of electrolysis and atomization methods, the liquid phase reduction method has the characteristics of easy availability of materials, safety and environmental protection, simple process, low energy consumption, and is suitable for large-scale production of copper powder.

[0004] In the electrical and electronics industry, conductive metal materials primarily require powders with high sphericity, good oxidation resistance, and a narrow particle size distribution to ensure that the slurry possesses good rheological properties, conductivity, and sintering performance. However, existing copper powder preparation methods produce copper powders with low sphericity, large shape variations, poor uniformity, complex processes, and susceptibility to oxidation.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a method for preparing spherical copper powder, aiming to solve the technical problems of low sphericity, large shape differences, poor uniformity, complex process and easy oxidation of copper powder prepared by existing copper powder preparation methods.

[0007] A second object of the present invention is to provide a spherical copper powder.

[0008] A third object of the present invention is to provide an application of spherical copper powder in the preparation of electronic paste or catalytic material.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A first aspect of the present invention provides a method for preparing spherical copper powder, comprising the following steps:

[0011] A. Add copper salt solution and reducing solution to the reaction base solution under stirring to react;

[0012] B. After the reaction is completed, a coating agent solution is added for coating, followed by solid-liquid separation, washing and filtration to obtain a paste-like copper powder;

[0013] C. adding the paste-like copper powder to a modifier solution for surface modification, and then filtering and drying to obtain the spherical copper powder.

[0014] Furthermore, the copper salt solution includes a soluble copper salt and a stabilizer.

[0015] Preferably, the soluble copper salt includes at least one of copper chloride, copper sulfate, copper nitrate and copper acetate.

[0016] Preferably, the stabilizer comprises an amine-based compound.

[0017] Preferably, the amino compound includes at least one of triethanolamine, diethanolamine, ethylenediamine, diethylenetriamine and ethylenediaminetetraacetic acid.

[0018] Preferably, the concentration of the soluble copper salt is 0.1 mol / L-0.5 mol / L, preferably 0.3 mol / L.

[0019] Preferably, the amount of the stabilizer is 0.5%-2% by mass of the soluble copper salt.

[0020] Furthermore, the reaction base liquid includes a protective agent and a reducing agent.

[0021] Preferably, the protective agent comprises a macromolecular polymer.

[0022] Preferably, the macromolecular polymer comprises at least one of PVP, gelatin and gum arabic.

[0023] Preferably, the reducing agent comprises ascorbic acid or isoascorbic acid.

[0024] Preferably, the amount of the protective agent in the reaction base liquid is 1%-10% by mass of the soluble copper salt, preferably 4%-5%, more preferably 4.5%.

[0025] Preferably, the concentration of the reducing agent in the reaction base solution is 0.1 mol / L-0.5 mol / L, preferably 0.3 mol / L.

[0026] Furthermore, the reducing agent in the reducing solution includes ascorbic acid or isoascorbic acid.

[0027] Preferably, the concentration of the reducing solution is 0.2 mol / L-1.0 mol / L, preferably 0.6 mol / L.

[0028] Furthermore, the coating agent in the coating agent solution includes at least one of sodium laurate, sodium palmitate, sodium stearate and sodium oleate.

[0029] Preferably, the mass percentage concentration of the coating agent solution is 2%-5%.

[0030] Preferably, the amount of the coating agent is 0.1%-1% of the soluble copper salt content, preferably 0.4%.

[0031] Furthermore, the modifier in the modifier solution includes at least one of oleylamine, dodecylamine and palmitamine.

[0032] Preferably, the mass percentage concentration of the modifier solution is 0.5%-5%, preferably 1%.

[0033] Preferably, the amount of the modifier used is 1%-5% of the soluble copper salt content, preferably 2%.

[0034] Furthermore, in step A, the copper salt solution and the reducing solution are added to the reaction base solution at a constant rate, and the addition time is 10 min-30 min.

[0035] Preferably, in step A, the reaction time is 30 min-90 min.

[0036] Preferably, in step B, the coating time is 5 min-8 min.

[0037] Preferably, in step C, the surface modification time is 5 min-10 min.

[0038] Preferably, in step C, the drying temperature is 40° C.-50° C., and the drying time is 2 h-4 h.

[0039] The second aspect of the present invention provides spherical copper powder prepared by the preparation method.

[0040] Furthermore, the particle size is 300nm-900nm; D50≤800nm.

[0041] Preferably, the particle size distribution SPAN value is 0.85-1.15.

[0042] Preferably, the tap density is 2.9 g / cm 3 -3.9g / cm 3 .

[0043] The third aspect of the present invention provides the use of the quasi-spherical copper powder in the preparation of electronic materials, chemical catalysis or metal surface repair.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] The method for preparing quasi-spherical copper powder provided by the present invention does not require inert atmosphere protection. By regulating the reaction base liquid and reducing liquid with a mild reducing agent and a copper salt solution, quasi-spherical copper powder with uniform particle size is obtained. Furthermore, by using coating and surface modification processes, oxidation of the copper powder is controlled during the reaction, cleaning, and storage processes, thereby improving the copper powder's oxidation resistance.

[0046] The quasi-spherical copper powder provided by the present invention has a quasi-spherical structure, a particle size of 300nm to 900nm, a narrow and uniform particle size distribution, high purity, high stability, excellent conductivity, and a wide range of applications.

[0047] The application of the quasi-spherical copper powder provided by the present invention in the preparation of electronic materials, chemical catalysis or metal surface repair, in view of the advantages of the above-mentioned quasi-spherical copper powder, is conducive to the preparation of electronic materials with better performance, better chemical catalysis performance and metal surface repair ability, and is conducive to the development of downstream industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1 This is a SEM photo of the spherical copper powder obtained in Example 1;

[0050] Figure 2 This is a SEM photo of the spherical copper powder obtained in Example 2;

[0051] Figure 3 This is a SEM photo of the spherical copper powder obtained in Example 3;

[0052] Figure 4 This is a SEM photo of the spherical copper powder obtained in Example 4;

[0053] Figure 5 This is a SEM photo of the spherical copper powder obtained in Example 8;

[0054] Figure 6 This is a SEM photograph of the spherical copper powder obtained in Example 9;

[0055] Figure 7 This is a SEM photograph of the spherical copper powder obtained in Example 10;

[0056] Figure 8 This is a SEM photo of the copper powder obtained in Comparative Example 1;

[0057] Figure 9 This is the SEM photo of the copper powder obtained in Comparative Example 2;

[0058] Figure 10 This is the EDS characterization diagram of the copper powder obtained in Comparative Example 1;

[0059] Figure 11 This is the EDS characterization diagram of the copper powder obtained in Comparative Example 2. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0061] A first aspect of the present invention provides a method for preparing spherical copper powder, comprising the following steps:

[0062] A. Add copper salt solution and reducing solution to the reaction base solution under stirring to react;

[0063] B. After the reaction is completed, a coating agent solution is added for coating, followed by solid-liquid separation, washing and filtration to obtain a paste-like copper powder;

[0064] C. adding the paste-like copper powder to a modifier solution for surface modification, and then filtering and drying to obtain the spherical copper powder.

[0065] The method for preparing quasi-spherical copper powder provided by the present invention does not require inert atmosphere protection. By regulating the reaction base liquid and reducing liquid with a mild reducing agent and a copper salt solution, quasi-spherical copper powder with uniform particle size is obtained. Furthermore, by using coating and surface modification processes, oxidation of the copper powder is controlled during the reaction, cleaning, and storage processes, thereby improving the copper powder's oxidation resistance.

[0066] Furthermore, the copper salt solution includes a soluble copper salt and a stabilizer.

[0067] Preferably, the soluble copper salt includes at least one of copper chloride, copper sulfate, copper nitrate and copper acetate.

[0068] Preferably, the stabilizer comprises an amine-based compound.

[0069] Preferably, the amino compound includes at least one of triethanolamine, diethanolamine, ethylenediamine, diethylenetriamine and ethylenediaminetetraacetic acid.

[0070] The stabilizer has a complexing effect with copper ions, and copper atoms precipitated from the solution adhere to the surface of existing copper atoms, preventing copper powder from oxidizing and controlling the uniform distribution of copper particle size.

[0071] Preferably, the concentration of the soluble copper salt is 0.1 mol / L-0.5 mol / L, preferably 0.3 mol / L.

[0072] Typically, but not limiting, the concentration of the soluble copper salt may be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0073] Preferably, the amount of the stabilizer is 0.5%-2% by mass of the soluble copper salt.

[0074] When the stabilizer dosage is less than 0.5% by weight of the soluble copper salt, the initial reaction of the copper salt solution is rapid, resulting in a wider particle size distribution of the synthesized copper particles. When the stabilizer dosage exceeds 2% by weight of the soluble copper salt, the synthesized copper particles become smaller in size because the excess stabilizer affects the liquid environment in which the copper particles grow, resulting in needle-like and flake-like structures and a disorganized morphology. Typically, but not limiting, the stabilizer dosage can be 0.5%, 1%, 1.5%, or 2% by weight of the soluble copper salt.

[0075] Furthermore, the reaction base solution includes a protective agent and a reducing agent. The reducing agent contained in the reaction base solution can provide a large reaction driving force in the early stage of the reaction, promoting the precipitation of a large amount of copper ions from the solution, and the presence of the protective agent can inhibit the growth of copper atoms, thereby producing more primary crystal nuclei of copper.

[0076] Preferably, the protective agent comprises a macromolecular polymer. The macromolecular polymer contains multiple functional groups, which play the role of steric hindrance and electrostatic steric hindrance, preventing the generated copper atoms from agglomerating, and facilitating the production of copper powder with uniform particle size distribution.

[0077] Preferably, the macromolecular polymer comprises at least one of PVP, gelatin and gum arabic.

[0078] Preferably, the reducing agent comprises ascorbic acid or isoascorbic acid.

[0079] Preferably, the amount of the protective agent in the reaction base liquid is 1%-10% by mass of the soluble copper salt, preferably 4%-5%, more preferably 4.5%.

[0080] When the protective agent dosage is less than 1% of the mass of the soluble copper salt, the particle size of the copper particles synthesized by the reaction increases, and significant agglomeration occurs between the particles. When the protective agent dosage exceeds 10% of the mass of the soluble copper salt, the viscosity of the base solution increases, and smaller copper particles can be obtained. However, this is not conducive to the cleaning, coating, and drying processes of the copper particles, and a large amount of water is required to clean the copper particles, which is a complex and costly process. Typically, but not limiting, the protective agent dosage can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% of the mass of the soluble copper salt.

[0081] Preferably, the concentration of the reducing agent in the reaction base solution is 0.1 mol / L-0.5 mol / L, preferably 0.3 mol / L.

[0082] During the entire reaction process, the molar ratio of electron transfer between the reducing agent and the copper salt during the redox reaction is 2:1. Here, the amount of the reducing agent used in the entire reaction process includes the reducing agent in the reaction base liquid and the reducing agent in the reducing liquid.

[0083] Typically, but not limiting, the concentration of the reducing agent may be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0084] The reducing agent in the reaction base liquid accounts for 30%-50% of the reducing agent mass in the entire reaction process, providing reaction power for the initial reaction.

[0085] Furthermore, the reducing agent in the reducing solution includes ascorbic acid or isoascorbic acid.

[0086] The reducing agent in the reaction base liquid and the reducing agent in the reducing liquid of the present application are both acidic reducing agents, and the reaction liquid after the reaction is also acidic, which prevents the formation of copper particles in other shapes such as needles and flakes, thereby ensuring the formation of spherical copper particles.

[0087] Preferably, the concentration of the reducing solution is 0.2 mol / L-1.0 mol / L, preferably 0.6 mol / L.

[0088] Typically, but not limited to, the concentration of the reducing solution may be 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1.0 mol / L.

[0089] Furthermore, the coating agent in the coating agent solution includes at least one of sodium laurate, sodium palmitate, sodium stearate and sodium oleate.

[0090] Sodium laurate, sodium palmitate, sodium stearate, and sodium oleate, as coating agents, all contain hydrophilic and hydrophobic groups. These effectively prevent contact with oxygen during the copper powder cleaning process, reducing the risk of copper powder oxidation. Furthermore, the coating agent coats the surface of the resulting spherical copper particles, preventing them from agglomerating.

[0091] Preferably, the mass percentage concentration of the coating agent solution is 2%-5%.

[0092] Preferably, the amount of the coating agent is 0.1%-1% of the soluble copper salt content, preferably 0.4%.

[0093] When the amount of coating agent used is less than 0.1% of the mass of the soluble copper salt, the average coating agent content obtained on the surface of the copper particles during the coating process is low, the coating effect is poor, and the copper particles have weak antioxidant properties. When the amount of coating agent used is greater than 1% of the mass of the soluble copper salt, under the condition of a certain particle size of the copper particles, based on the specific surface area, the coating agent required for complete surface coating is within the range defined by this solution. Even if the amount of coating agent is further increased, the antioxidant properties will not be improved, and the material loss will increase, resulting in high costs. Typically, but not limiting, the amount of coating agent used can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1% of the mass of the soluble copper salt.

[0094] Furthermore, the modifier in the modifier solution includes at least one of oleylamine, dodecylamine, and palmitamine. These modifiers are long-chain organic compounds containing amine groups, which amidate carboxyl groups on the surface of the copper particles with amine groups, coating the copper powder surface and further enhancing the copper powder's antioxidant properties.

[0095] Unless otherwise specified in the present invention, the solvent of all solutions is water, preferably deionized water, to reduce the cost of industrial production.

[0096] Since the modifier is an organic substance, alcohol is preferably used as a solvent to prepare the modifier solution to improve the solubility of the modifier.

[0097] Preferably, the mass percentage concentration of the modifier solution is 0.5%-5%, preferably 1%.

[0098] Preferably, the amount of the modifier used is 1%-5% of the soluble copper salt content, preferably 2%.

[0099] When the modifier dosage is less than 1% by weight of the soluble copper salt, the degree of amidation is low and the antioxidant properties of the copper particles are not significantly enhanced. When the modifier dosage is greater than 5% by weight of the soluble copper salt, similarly due to the effect of specific surface area, the amidation on the surface of the copper particles reaches a threshold and does not continue to increase. Therefore, the optimized dosage is limited to 1-5% as proposed in this solution. Typically, but not limiting, the modifier dosage can be 1%, 2%, 3%, 4%, or 5% by weight of the soluble copper salt.

[0100] The two-step treatment of coating agent and modifier enhances the antioxidant effect of copper powder.

[0101] Furthermore, in step A, the copper salt solution and the reducing solution are added to the reaction base solution at a constant rate, and the addition time is 10 min-30 min.

[0102] Preferably, in step A, the reaction time is 30 min to 90 min. Since copper ions are blue, the reaction endpoint can be determined by the color change during the reaction, thereby controlling the reaction time. After the reaction is completed, the blue color of the reaction solution disappears and turns reddish brown.

[0103] Preferably, in step B, the coating time is 5 min-8 min.

[0104] Preferably, in step C, the surface modification time is 5 min-10 min.

[0105] Preferably, in step C, the drying temperature is 40° C.-50° C., and the drying time is 2 h-4 h.

[0106] The second aspect of the present invention provides spherical copper powder prepared by the preparation method.

[0107] The quasi-spherical copper powder provided by the present invention has a particle size of 300nm to 900nm, a narrow and uniform particle size distribution, and a wide range of applications.

[0108] Furthermore, the particle size is 300nm-900nm; D50≤800nm.

[0109] Preferably, the particle size distribution SPAN value is 0.85-1.15.

[0110] It should be noted that the SPAN value is the value calculated by (D90-D10) / D50 in the particle size, which can show the distribution range of the particle size.

[0111] Preferably, the tap density is 2.9 g / cm 3 -3.9g / cm 3 .

[0112] The third aspect of the present invention provides the use of the quasi-spherical copper powder in the preparation of electronic materials, chemical catalysis or metal surface repair.

[0113] The application of the quasi-spherical copper powder provided by the present invention in the preparation of electronic materials, chemical catalysis or metal surface repair, in view of the advantages of the above-mentioned quasi-spherical copper powder, is conducive to the preparation of electronic materials with better performance, better chemical catalysis performance and metal surface repair ability, and is conducive to the development of downstream industries.

[0114] Below, some embodiments of the present invention are described in detail with reference to the examples. In the absence of conflict, the following embodiments and features therein can be combined with each other. Unless otherwise specified, the raw materials used in the present invention can be obtained by commercial purchase.

[0115] Example 1

[0116] This embodiment provides a spherical copper powder, and the preparation process is as follows:

[0117] 1. Liquid preparation: Dissolve 37.5 g of copper sulfate and 0.4 g of ethylenediaminetetraacetic acid in 1000 ml of deionized water to obtain a copper salt solution; dissolve 21.12 g of ascorbic acid and 2 g of gum arabic in 400 ml of deionized water to obtain a reaction base solution; dissolve the remaining 31.68 g of ascorbic acid in 300 ml of deionized water to obtain a reducing solution; prepare a 2% deionized water solution of sodium laurate as a coating agent solution; and prepare a 1% alcohol solution of dodecylamine as a modifier solution.

[0118] 2. The reaction base liquid was placed in a reactor and stirred at 400 r / min. The copper salt solution and the reducing solution were added to the reaction base liquid at a constant rate at room temperature for 10 minutes. After the addition was completed, the reaction was continued for 30 minutes. The reaction liquid gradually changed from blue to reddish brown.

[0119] 3. After the reaction is completed, 7.5 ml of the coating agent solution is added to the above reaction solution, and the stirring speed is reduced to 100 r / min, and stirring is continued for 5 minutes to perform a coating treatment; then the copper powder is separated from the solid and liquid, washed with deionized water 4 times, and filtered to obtain a paste copper powder.

[0120] 4. Add the paste copper powder to 75 ml of the modifier solution and stir at 400 rpm for 10 minutes for further surface modification. Then filter and dry in an oven at 40°C for 3 hours to obtain approximately 14.3 g of spherical copper powder.

[0121] Example 2

[0122] This embodiment provides a quasi-spherical copper powder. The difference from Example 1 is that 3.7 g of PVP-K90 is used instead of 2 g of gum arabic. The remaining raw materials and steps are the same as those in Example 1 and are not repeated here.

[0123] Example 3

[0124] This embodiment provides a quasi-spherical copper powder. The difference from Example 1 is that ascorbic acid in the reaction base liquid is replaced by isoascorbic acid. The remaining raw materials and steps are the same as those in Example 1 and are not repeated here.

[0125] Example 4

[0126] This embodiment provides a quasi-spherical copper powder. The difference from Example 1 is that sodium oleate is used instead of sodium laurate, and oleylamine is used instead of dodecylamine. The remaining raw materials and steps are the same as those in Example 1 and are not repeated here.

[0127] Example 5

[0128] This embodiment provides a quasi-spherical copper powder. In step 1, 15.9 g of copper sulfate and 0.8 g of ethylenediaminetetraacetic acid are dissolved in 1000 ml of deionized water to obtain a copper salt solution; 21.12 g of ascorbic acid and 1.6 g of gum arabic are dissolved in 400 ml of deionized water to obtain a reaction base solution; the other solution proportions are the same as in Example 1 and are not repeated here.

[0129] Example 6

[0130] This embodiment provides a quasi-spherical copper powder. In step 1, 26.4 g of ascorbic acid and 2 g of gum arabic are dissolved in 400 ml of deionized water to obtain a reaction base solution; the remaining 26.4 g of ascorbic acid is dissolved in 300 ml of deionized water to obtain a reducing solution; the other solution ratios are the same as in Example 1 and are not repeated here.

[0131] Example 7

[0132] This embodiment provides a quasi-spherical copper powder. In step 1, 31.68 g of ascorbic acid and 2 g of gum arabic are dissolved in 400 ml of deionized water to obtain a reaction base solution; the remaining 21.12 g of ascorbic acid is dissolved in 300 ml of deionized water to obtain a reducing solution; the other solution ratios are the same as in Example 1 and are not repeated here.

[0133] Example 8

[0134] This embodiment provides a quasi-spherical copper powder. The difference from Example 1 is that gum arabic is not added to the reaction base liquid. The remaining raw materials and methods are the same as those in Example 1 and are not described again here.

[0135] Example 9

[0136] This embodiment provides a quasi-spherical copper powder. The difference from Example 1 is that the amount of EDTA is changed to 1.9 g. The remaining raw materials and methods are the same as those in Example 1 and are not described again here.

[0137] Example 10

[0138] This embodiment provides a quasi-spherical copper powder. The difference from Example 1 is that no ascorbic acid is added to the reaction base solution, and all the ascorbic acid is added to the reducing solution. The remaining raw materials and methods are the same as those in Example 1 and are not repeated here.

[0139] Comparative Example 1

[0140] This comparative example provides a copper powder. Unlike Example 1, no coating agent solution is used. The remaining raw materials and methods are the same as those in Example 1 and are not described again here.

[0141] Comparative Example 2

[0142] This comparative example provides a copper powder. Unlike Example 1, no modifier solution is used. The remaining raw materials and methods are the same as those in Example 1 and are not described again here.

[0143] Test Example 1

[0144] The copper powder particle size obtained in Examples 1-10 and Comparative Examples 1-2 was measured. The measurement instrument used was a transmission electron microscope to observe the morphology and size of the copper powder particles, and the size and particle size distribution of the copper powder were statistically analyzed using ImageJ measurement software. The tap density of the copper particles was obtained using a Dandong Better tap density meter at a frequency of 200 times per minute. The data are shown in Table 1 below.

[0145] Table 1 Particle size statistics

[0146] D50 / nm SPAN value <![CDATA[Tap density / g / cm 3 > Example 1 764 0.94 3.84 Example 2 439 0.86 2.98 Example 3 688 1.13 3.76 Example 4 759 1.05 3.59 Example 5 678 1.16 3.77 Example 6 738 1.04 3.55 Example 7 741 1.11 3.49 Example 8 1870 1.87 4.01 Example 9 Messy appearance / 2.55 Example 10 500 1.89 2.68 Comparative Example 1 932 1.08 3.66 Comparative Example 2 821 1.22 3.85

[0147] As shown in Table 1, within the specified formulation limits, copper particles with a D50 diameter of less than 800 nm can be obtained. The stabilizer and protective agent content has a critical influence on the size and distribution of copper particles. A higher or lower content will cause variations in copper particle size and also affect the microscopic morphology of the copper particles. On the other hand, when no coating agent or modifier is added, the copper particles oxidize on the surface, increasing their size.

[0148] Test Example 2

[0149] The copper powders obtained in Examples 1-4, 8-10 and Comparative Example 1-2 were subjected to SEM, and the obtained SEM photographs correspond to the following: Figures 1-9 shown.

[0150] from Figure 1It can be seen that the copper powder obtained in Example 1 has a smooth surface and uniform particle size; Figure 2 It can be seen that the copper powder obtained in Example 2 has good particle size uniformity. Figure 3 It can be seen that the copper powder obtained in Example 3 has a spherical structure; Figure 4 It can be seen that the copper powder obtained in Example 4 has a smooth surface and is not oxidized. Figure 5 It can be seen that the copper powder particles obtained in Example 8 are significantly larger; Figure 6 It can be seen that the copper powder obtained in Example 9 is spherical and needle-shaped copper particles, among which the copper particles with needle-shaped surfaces are significantly larger; Figure 7 It can be seen that the copper powder obtained in Example 10 is spherical, and there are still unreacted rod-shaped organic matter with high carbon, hydrogen and oxygen content in the product; the copper powder is oxidized during the preparation process of Comparative Example 1, and the color of the copper powder partially turns black. Figure 8 It can be seen that the copper powder particles have a shell-like copper oxide or cuprous oxide substance; similarly, Figure 9 It can be seen that there are obviously oxidized small particles on the surface of the copper powder of Comparative Example 2, the copper powder is oxidized, and the color of the finished product is slightly blackened.

[0151] Test Example 3

[0152] The copper powder obtained in Comparative Example 1-2 was characterized by EDS, and the obtained EDS photographs corresponded to the following: Figure 10 、 Figure 11 shown.

[0153] The atomic percentage of oxygen in the copper powder obtained in Comparative Example 1 was 13.27%, and the atomic percentage of copper was 86.73%; the atomic percentage of oxygen in the copper powder obtained in Comparative Example 2 was 14.85%, and the atomic percentage of copper was 85.15%; both had oxidation.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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: The following steps are involved: A. Add copper salt solution and reducing solution to the reaction base solution under stirring to react; B. After the reaction is completed, a coating agent solution is added for coating, followed by solid-liquid separation, washing and filtration to obtain a paste-like copper powder; C. adding the paste copper powder to a modifier solution for surface modification, and then filtering and drying to obtain the spherical copper powder; The copper salt solution includes a soluble copper salt and a stabilizer; The soluble copper salt includes at least one of copper chloride, copper sulfate, copper nitrate and copper acetate; The stabilizer includes an amino compound; The amino compound includes at least one of triethanolamine, diethanolamine, ethylenediamine, diethylenetriamine and ethylenediaminetetraacetic acid; The concentration of the soluble copper salt is 0.1 mol / L-0.5 mol / L; The amount of the stabilizer is 0.5%-2% of the mass of the soluble copper salt; The reaction base liquid includes a protective agent and a reducing agent; The protective agent includes a macromolecular polymer; The macromolecular polymer includes at least one of PVP, gelatin and gum arabic; The reducing agent includes ascorbic acid or isoascorbic acid; In the reaction base solution, the amount of the protective agent is 1%-10% of the mass of the soluble copper salt; In the reaction base solution, the concentration of the reducing agent is 0.1 mol / L-0.5 mol / L; The reducing agent in the reducing solution includes ascorbic acid or isoascorbic acid; The concentration of the reducing solution is 0.2mol / L-1.0mol / L; The coating agent in the coating agent solution includes at least one of sodium laurate, sodium palmitate, sodium stearate and sodium oleate; The mass percentage concentration of the coating agent solution is 2%-5%; The amount of the coating agent is 0.1%-1% of the soluble copper salt content; The modifier in the modifier solution includes at least one of oleylamine, dodecylamine and palmitamine; The mass percentage concentration of the modifier solution is 0.5%-5%; The dosage of the modifier is 1%-5% of the soluble copper salt content.

2. The preparation method according to claim 1, characterized in that The concentration of the soluble copper salt is 0.3 mol / L.

3. The preparation method according to claim 1, characterized in that In the reaction base solution, the amount of the protective agent is 4%-5% of the mass of the soluble copper salt.

4. The preparation method according to claim 1, characterized in that In the reaction base solution, the amount of the protective agent is 4.5% of the mass of the soluble copper salt.

5. The preparation method according to claim 1, characterized in that The concentration of the reducing agent in the reaction base solution is 0.3 mol / L.

6. The preparation method according to claim 1, characterized in that The concentration of the reducing solution is 0.6 mol / L.

7. The preparation method according to claim 1, characterized in that The amount of the coating agent is 0.4% of the soluble copper salt content.

8. The preparation method according to claim 1, characterized in that The mass percentage concentration of the modifier solution is 1%.

9. The preparation method according to claim 1, characterized in that The dosage of the modifier is 2% of the soluble copper salt content.

10. The preparation method according to claim 1, characterized in that In step A, the copper salt solution and the reducing solution are added to the reaction base solution at a constant rate, and the addition time is 10 min to 30 min.

11. The preparation method according to claim 1, characterized in that In step A, the reaction time is 30 min-90 min.

12. The preparation method according to claim 1, characterized in that In step B, the coating time is 5 min-8 min.

13. The preparation method according to claim 1, characterized in that In step C, the surface modification time is 5 min-10 min.

14. The preparation method according to claim 1, characterized in that In step C, the drying temperature is 40° C.-50° C., and the drying time is 2 h-4 h.

15. A spherical copper powder prepared according to the preparation method according to any one of claims 1 to 14.

16. The spherical copper powder according to claim 15, characterized in that Particle size is 300nm-900nm; D50≤800nm.

17. The spherical copper powder according to claim 15, characterized in that The particle size distribution SPAN value is 0.85-1.

15.

18. The spherical copper powder according to claim 15, characterized in that Tap density is 2.9g / cm 3 -3.9g / cm 3 .

19. Use of the quasi-spherical copper powder according to any one of claims 15 to 18 in the preparation of electronic materials, chemical catalysis or metal surface repair.

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