Spherical-like micron-sized superfine copper powder and preparation method thereof

Abstract

The invention provides sphere-like micron-sized superfine copper powder and a preparation method thereof, and belongs to the technical field of metal powder preparation.The preparation method comprises the following steps that soluble copper salt and a complexing agent are dispersed in deionized water, sodium hydroxide is added to adjust the pH value, then a dispersing agent is added, and copper salt dispersion liquid is obtained; a reducing agent is dispersed in deionized water, sodium hydroxide is added to adjust the pH, and a reducing solution is obtained; adding the copper salt dispersion liquid into the reduction solution, and stirring for reaction; and after the reaction is finished, carrying out solid-liquid separation, cleaning and drying to obtain the sphere-like micron-sized superfine copper powder. According to the method for preparing the sphere-like micron-sized copper powder through the liquid phase reduction method, the average particle size of the copper powder is 2.5-3.0 microns, reaction raw materials are easy to obtain, the technological process is simple, and the requirement of large-scale industrial production can be met.

Description

Technical Field

[0001] This invention relates to the field of metal powder preparation technology, specifically to a spherical micron-sized ultrafine copper powder and its preparation method. Background Technology

[0002] With the rapid development of the electronics industry, the performance requirements for copper powder in conductive materials are becoming increasingly stringent. Spherical, micron-sized ultrafine copper powder, due to its high tap density, excellent dispersibility, and oxidation resistance, has significant application value in fields such as multilayer ceramic capacitors (MLCCs), conductive pastes, and 3D printing.

[0003] Currently, the mainstream methods for preparing copper powder include atomization, electrolysis, and chemical reduction. Atomization requires high equipment investment and energy consumption, and the resulting product has a wide particle size distribution, low sphericity, and significant shape variations, necessitating secondary sieving. While electrolysis can produce high-purity copper powder, the process is complex, costly, and difficult to control morphology. In contrast, liquid-phase chemical reduction has attracted considerable attention due to its controllable morphology and particle size, low production cost, and suitability for mass production. However, ultrafine copper powder prepared by liquid-phase chemical reduction still suffers from poor sphericity, uneven particle size distribution, long production process, and insufficient environmental friendliness. Summary of the Invention

[0004] In view of the technical problems existing in the background art, this application provides a spherical micron-sized ultrafine copper powder and its preparation method, aiming to solve the technical problems of poor sphericity, uneven particle size distribution, long production process and insufficient environmental friendliness of the ultrafine copper powder prepared by the prior art.

[0005] In a first aspect, embodiments of this application provide a method for preparing spherical, micron-sized ultrafine copper powder, comprising the following steps: Soluble copper salt and complexing agent are dispersed in deionized water, sodium hydroxide is added to adjust the pH to 6.0-9.0, and then dispersant is added to obtain copper salt dispersion; Disperse the reducing agent in deionized water, add sodium hydroxide to adjust the pH to 6.0-9.0, and obtain a reducing solution; Add the copper salt dispersion to the reducing solution and stir to react; After the reaction was completed, solid-liquid separation, washing, and drying were performed to obtain spherical micron-sized ultrafine copper powder.

[0006] In some embodiments, the soluble copper salt is at least one of copper sulfate, copper nitrate, copper chloride, and copper acetate; The concentration of copper ions in the copper salt dispersion is 0.1~3.0 mol / L.

[0007] In some embodiments, the complexing agent is sodium citrate or ammonia, and the molar ratio of the complexing agent to the soluble copper salt is (1~1.5):1.

[0008] In some embodiments, the dispersant is at least one of sodium pyrophosphate, potassium pyrophosphate, polyvinylpyrrolidone, sodium tartrate, polyethylene glycol, sodium tripolyphosphate, sodium metaphosphate, and gelatin.

[0009] In some embodiments, the amount of dispersant added is 1.0% to 5.0% of the mass of the near-spherical micron-sized ultrafine copper powder.

[0010] In some embodiments, the copper salt dispersion and the reducing solution are heated to 30-80°C.

[0011] In some embodiments, after stirring the reaction for 3 to 6 hours, a coating agent is added.

[0012] In some embodiments, the coating agent is at least one of lauric acid, oleic acid, and stearic acid, and the amount of coating agent added is 0.1% to 1.0% of the mass of the spherical micron-sized ultrafine copper powder.

[0013] Secondly, embodiments of this application provide a spherical micron-sized ultrafine copper powder, which is prepared using the above-described method.

[0014] In some embodiments, the particle size of the near-spherical micron-sized ultrafine copper powder is 2.5~3.0μm.

[0015] The advantages of this application, which differ from existing technical solutions, include: 1. This invention provides a method for preparing near-spherical micron-sized copper powder by liquid-phase reduction. The copper powder has an average particle size of 2.5~3.0μm, the raw materials are readily available, the process is simple, and it can meet the requirements of large-scale industrial production.

[0016] 2. In this invention, sodium citrate or ammonia is added as a complexing agent, which can form a stable complex with copper ions, thereby regulating the nucleation reaction rate and making the copper powder grains grow more uniformly. By adjusting the pH of the copper salt dispersion and the reducing solution to 6.0~9.0 with sodium hydroxide and maintaining the same pH before the reaction, the prepared near-spherical micron-sized copper powder has good sphericity and relatively uniform particle size. Moreover, this invention reacts under neutral conditions, which has less corrosiveness to equipment. The reaction temperature is 30~80℃, the process is simple and environmentally friendly, and it can be used for large-scale production.

[0017] 3. In this invention, sodium pyrophosphate is added as a dispersant, which can form a protective film on the surface of copper powder particles through adsorption, reduce the interaction force between particles, limit the occurrence of agglomeration, and improve the dispersibility, stability and uniformity of copper powder.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0020] Figure 1 This is a SEM image of the near-spherical micron-sized ultrafine copper powder in Example 1; Figure 2 This is an SEM image of the near-spherical micron-sized ultrafine copper powder in Example 2; Figure 3 This is a SEM image of the near-spherical micron-sized ultrafine copper powder in Example 3; Figure 4 SEM image of the near-spherical micron-sized ultrafine copper powder in Comparative Example 1; Figure 5 SEM image of the near-spherical micron-sized ultrafine copper powder in Comparative Example 2; Figure 6 The image shows a SEM image of the near-spherical micron-sized ultrafine copper powder in Comparative Example 3. Detailed Implementation

[0021] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0022] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0023] I. Preparation Method Example 1 A method for preparing near-spherical micron-sized copper powder includes the following steps: S1: Weigh 423g of copper nitrate and 618g of sodium citrate and dissolve them in 1500mL of deionized water. Add 72.6g of sodium hydroxide to adjust the pH of the solution to 7.0. Then weigh 28g of sodium pyrophosphate and add it to the above solution. Stir and dissolve evenly to obtain a copper nitrate dispersion.

[0024] S2: Weigh 924g of ascorbic acid and dissolve it in 2000mL of water to prepare a reducing solution. Add 212.8g of sodium hydroxide to adjust the pH of the solution to 7.0.

[0025] S3: After heating the copper nitrate dispersion from step S1 and the reducing solution from step S2 to 50°C, add the copper nitrate dispersion to the reducing solution, continue the reaction for 5 hours, and then add 0.4 g of lauric acid.

[0026] S4: After the reaction is complete, solid-liquid separation is performed, and the product is washed multiple times with deionized water and ethanol and then dried to obtain spherical micron-sized copper powder.

[0027] The SEM image of the ultrafine copper powder prepared according to Example 1 is shown below. Figure 1 As shown, the copper powder is spherical with a relatively uniform particle size distribution. The average particle size is 2.8 μm, which shows good dispersibility and no obvious agglomeration. The tap density reaches 4.8 g / mL.

[0028] Example 2 A method for preparing near-spherical micron-sized copper powder includes the following steps: S1: Weigh 423g of copper nitrate and 618g of sodium citrate and dissolve them in 1500mL of deionized water. Add 72.6g of sodium hydroxide to adjust the pH of the solution to 6.0. Then weigh 28g of PVP and add it to the above solution. Stir and dissolve evenly to obtain a copper nitrate dispersion.

[0029] S2: Weigh 924g of ascorbic acid and dissolve it in 2000mL of water to prepare a reducing solution. Add 212.8g of sodium hydroxide to adjust the pH of the solution to 8.0.

[0030] S3: After heating the copper nitrate dispersion from step S1 and the reducing solution from step S2 to 50°C, add the copper nitrate dispersion to the reducing solution, continue the reaction for 5 hours, and then add 0.4 g of lauric acid.

[0031] S4: After the reaction is complete, solid-liquid separation is performed, and the product is washed multiple times with deionized water and ethanol and then dried to obtain spherical micron-sized copper powder.

[0032] SEM images of the ultrafine copper powder prepared according to Example 2 are shown below. Figure 2As shown in the figure, the ultrafine copper powder is spherical with an average particle size of 3.0 μm. However, the particle size distribution and dispersibility are worse than those of Example 1, indicating that PVP is not as effective as sodium pyrophosphate as a dispersant. The tap density is 4.7 g / ml.

[0033] Example 3 A method for preparing near-spherical micron-sized copper powder includes the following steps: S1: Weigh 423g of copper nitrate and 618g of sodium citrate and dissolve them in 1500mL of deionized water. Add 72.6g of sodium hydroxide to adjust the pH of the solution to 8.0. Then weigh 28g of sodium pyrophosphate and add it to the above solution. Stir and dissolve evenly to obtain a copper nitrate dispersion.

[0034] S2: Weigh 924g of ascorbic acid and dissolve it in 2000mL of water to prepare a reducing solution. Add 212.8g of sodium hydroxide to adjust the pH of the solution to 6.0.

[0035] S3: After heating the copper nitrate dispersion from step S1 and the reducing solution from step S2 to 60°C, add the copper nitrate dispersion to the reducing solution and continue the reaction for 5 hours, then add 0.4 g of lauric acid.

[0036] S4: After the reaction is complete, solid-liquid separation is performed, and the product is washed multiple times with deionized water and ethanol and then dried to obtain spherical micron-sized copper powder.

[0037] The SEM image of the ultrafine copper powder prepared according to Example 3 is shown below. Figure 3 As shown, obvious agglomeration of copper powder can be observed. Compared with Examples 1 and 2, the average particle size of copper powder increased to 3.3 μm.

[0038] Comparative Example 1 A method for preparing near-spherical micron-sized copper powder, which, compared to Example 1, does not involve the addition of a dispersant, includes the following steps: S1: Weigh 423g of copper nitrate and 618g of sodium citrate and dissolve them in 1500mL of deionized water. Add 72.6g of sodium hydroxide to adjust the pH of the solution to 7.0 and stir until dissolved to obtain a copper nitrate dispersion.

[0039] S2: Weigh 924g of ascorbic acid and dissolve it in 2000mL of water to prepare a reducing solution. Add 212.8g of sodium hydroxide to adjust the pH of the solution to 7.0.

[0040] S3: After heating the copper nitrate dispersion from step S1 and the reducing solution from step S2 to 50°C, add the copper nitrate dispersion to the reducing solution, continue the reaction for 5 hours, and then add 0.4 g of lauric acid.

[0041] S4: After the reaction is complete, solid-liquid separation is performed, and the product is washed multiple times with deionized water and ethanol and then dried to obtain spherical micron-sized copper powder.

[0042] The SEM image of the ultrafine copper powder prepared according to Comparative Example 1 is shown below. Figure 4 As shown, the copper powder has an uneven particle size distribution and severe agglomeration, indicating that sodium pyrophosphate dispersant can improve the dispersibility and uniformity of copper powder.

[0043] Comparative Example 2 A method for preparing near-spherical micron-sized copper powder, which, compared to Example 1, does not require adjusting the pH of the reducing solution, includes the following steps: S1: Weigh 423g of copper nitrate and 618g of sodium citrate and dissolve them in 1500mL of deionized water. Add 65.2g of sodium hydroxide to adjust the pH of the solution to 7.0. Then weigh 28g of sodium pyrophosphate and add it to the above solution. Stir and dissolve evenly to obtain a copper nitrate dispersion.

[0044] S2: Weigh 924g of ascorbic acid and dissolve it in 2000mL of water to prepare a reducing solution.

[0045] S3: After heating the copper nitrate dispersion from step S1 and the reducing solution from step S2 to 50°C, add the copper nitrate dispersion to the reducing solution, continue the reaction for 5 hours, and then add 0.4 g of lauric acid.

[0046] S4: After the reaction is complete, solid-liquid separation is performed, and the product is washed multiple times with deionized water and ethanol and then dried to obtain spherical micron-sized copper powder.

[0047] The SEM image of the ultrafine copper powder prepared according to Comparative Example 1 is shown below. Figure 5 As shown, the copper powder particle size distribution is uneven, with particles of 1.3 μm and 5.0 μm in size. The large particles have irregular morphology, indicating that without adjusting the pH of the reducing solution, the pH of the reaction solution will be too low, which is not conducive to the preparation of copper powder with uniform particle size.

[0048] Comparative Example 3 A method for preparing near-spherical micron-sized copper powder, which has a higher pH value for the copper salt dispersion and reducing solution compared to Example 1, includes the following steps: S1: Weigh 423g of copper nitrate and 618g of sodium citrate and dissolve them in 1500mL of deionized water. Add 76.4g of sodium hydroxide to adjust the pH of the solution to 11.0. Then weigh 28g of sodium pyrophosphate and add it to the above solution. Stir and dissolve evenly to obtain a copper nitrate dispersion.

[0049] S2: Weigh 924g of ascorbic acid and dissolve it in 2000mL of water to prepare a reducing solution. Add 257.0g of sodium hydroxide to adjust the pH of the solution to 11.0.

[0050] S3: After heating the copper nitrate dispersion from step S1 and the reducing solution from step S2 to 50°C, add the copper nitrate dispersion to the reducing solution, continue the reaction for 5 hours, and then add 0.4 g of lauric acid.

[0051] S4: After the reaction is complete, solid-liquid separation is performed, and the product is washed multiple times with deionized water and ethanol and then dried to obtain spherical micron-sized copper powder.

[0052] The SEM image of the ultrafine copper powder prepared according to Comparative Example 2 is shown below. Figure 6 As shown, the copper powder exhibits a near-spherical shape with a particle size reduced by 400-500 nm, and shows slight agglomeration, indicating that the solution obtained under a strongly alkaline environment is nano-sized copper powder.

[0053] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing near-spherical micron-sized ultrafine copper powder, characterized in that, Includes the following steps: Soluble copper salt and complexing agent are dispersed in deionized water, sodium hydroxide is added to adjust the pH to 6.0~9.0, and then dispersant is added to obtain copper salt dispersion; The reducing agent is dispersed in deionized water, and sodium hydroxide is added to adjust the pH to 6.0-9.0 to obtain a reducing solution; The copper salt dispersion was added to the reducing solution, and the mixture was stirred to react. After the reaction was completed, solid-liquid separation, washing, and drying were performed to obtain spherical micron-sized ultrafine copper powder.

2. The method for preparing near-spherical micron-sized ultrafine copper powder according to claim 1, characterized in that, The soluble copper salt is at least one of copper sulfate, copper nitrate, copper chloride, and copper acetate; The copper ion concentration in the copper salt dispersion is 0.1~3.0 mol / L.

3. The method for preparing near-spherical micron-sized ultrafine copper powder according to claim 1, characterized in that, The complexing agent is sodium citrate or ammonia, and the molar ratio of the complexing agent to the soluble copper salt is (1~1.5):

1.

4. The method for preparing near-spherical micron-sized ultrafine copper powder according to claim 1, characterized in that, The dispersant is at least one of sodium pyrophosphate, potassium pyrophosphate, polyvinylpyrrolidone, sodium tartrate, polyethylene glycol, sodium tripolyphosphate, sodium metaphosphate, and gelatin.

5. The method for preparing near-spherical micron-sized ultrafine copper powder according to claim 1, characterized in that, The amount of dispersant added is 1.0% to 5.0% of the mass of the spherical micron-sized ultrafine copper powder.

6. The method for preparing near-spherical micron-sized ultrafine copper powder according to claim 1, characterized in that, The copper salt dispersion and reducing solution are heated to 30~80℃.

7. The method for preparing near-spherical micron-sized ultrafine copper powder according to claim 1, characterized in that, After stirring and reacting for 3-6 hours, a coating agent is added.

8. The method for preparing near-spherical micron-sized ultrafine copper powder according to claim 7, characterized in that, The coating agent is at least one of lauric acid, oleic acid, and stearic acid, and the amount of the coating agent added is 0.1% to 1.0% of the mass of the spherical micron-sized ultrafine copper powder.

9. A quasi-spherical micron-sized ultrafine copper powder, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 8.

10. A near-spherical micron-sized ultrafine copper powder as described in claim 9, characterized in that, The spherical micron-sized ultrafine copper powder has a particle size of 2.5~3.0μm.

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