Preparation method of nano copper powder

Abstract

The invention discloses a preparation method of nano copper powder, which comprises the following steps: 1, dissolving copper salt in deionized water to obtain a blue clear solution; 2, preparing an additive and a reducing agent A into a solution; 3, adding a solution into the blue clear solution to obtain a mixed solution B; 4, adding a reducing agent C into the mixed solution B to obtain a mixed solution D; 5, heating the mixed solution D to obtain an amaranth product; and sixthly, the purplish red product is centrifuged, washed and subjected to vacuum drying, and the nano copper powder with the particle size ranging from 80 nm to 100 nm is obtained. The copper salt is used as a raw material, through a two-step method, the additive and the reducing agent A are firstly added to effectively regulate and control the seed crystal nucleation rate, then the reducing agent C is added, the nanometer copper powder which is small in particle size, uniform in particle size distribution and good in dispersity and has oxidation resistance is obtained, and the technical limitation that at present, small-particle-size nanometer copper powder is serious in agglomeration and difficult to prepare on a large scale is broken through; the method is simple in process, high in operability and good in repeatability.

Description

Technical Field

[0001] The invention belongs to the technical field of metal nanomaterials, and particularly relates to a method for preparing nano copper powder. Background Art

[0002] Nano-copper powders, due to their unique optical, electrical, thermal, magnetic, and chemical properties, are widely used in electromagnetic shielding, high-efficiency catalysts, conductive pastes, high-performance alloys, lubricants, and antimicrobial applications. In particular, as a new conductive paste, they offer high conductivity and low cost. Currently, methods for producing nano-copper powders are primarily categorized into physical and chemical methods. Physical methods include traditional electrolysis, spherical graphite deposition, vapor deposition, plasma deposition, and explosive wire deposition. These methods are characterized by expensive equipment, complex processes, and high production costs. Currently, commercial nano-copper powders are primarily produced using physical vapor deposition (PVD). This method offers high sphericity, but the equipment and process are expensive and complex, resulting in a high price. Chemical methods include microemulsion deposition, solvothermal deposition, electrochemical deposition, liquid-phase chemical reduction, and thermal reduction.

[0003] Among them, liquid phase chemical reduction is the most commonly used method for preparing nano copper powder in the laboratory at present. It involves redox reaction between a copper salt precursor and a reducing agent in an aqueous phase or a solvent to reduce copper ions to nano copper particles of different morphologies and sizes. Although this method can generate a large amount of nano copper particles in a short period of time, due to its fast nucleation rate, the growth process is difficult to control, and it is easy to obtain nano particles with larger particle size, wider particle size distribution range and poor uniformity. Meanwhile, the nano copper powder with smaller particle size has a larger specific surface area and higher activity, and is very easily oxidized, thereby affecting its own performance. Therefore, although liquid phase reduction method has been widely studied in the preparation of nano copper powder, it is still a difficult problem to obtain an anti-oxidation nano copper powder with narrow particle size distribution, uniform size and smaller particles. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the above-mentioned existing technologies and provide a method for preparing nano-copper powder. This method uses a liquid-phase chemical reduction method to effectively control the crystal nucleation and growth rates through a two-step reaction, thereby obtaining nano-copper powder with a uniform particle size of 80nm to 100nm and a certain antioxidant capacity.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing nano copper powder, characterized in that the method comprises the following steps: Step 1: Dissolve copper salt in deionized water and stir evenly to obtain a blue clear solution; Step 2: preparing a solution with the additive and reducing agent A; Step 3: adding the solution prepared by the additive and reducing agent A in step 2 to the blue clear solution obtained in step 1 to obtain a mixed solution B; Step 4: Add reducing agent C to the mixed solution B obtained in step 3 and stir evenly to obtain a mixed solution D; Step 5: Place the mixed solution D obtained in step 4 into a reaction kettle, and then react in an oven at 90°C to 120°C for 1h to 5h to obtain a purple-red product; Step 6: The purple-red product obtained in step 5 is washed with deionized water and anhydrous ethanol in sequence, and vacuum-dried to obtain nano-copper powder with a particle size of 80 nm to 100 nm.

[0006] The above-mentioned method for preparing nano-copper powder is characterized in that the copper salt in step 1 is copper nitrate trihydrate, copper sulfate pentahydrate, copper chloride dihydrate, or copper acetate monohydrate. By controlling the type of copper salt, the present invention has a high solubility, which facilitates subsequent preparation.

[0007] The above-mentioned method for preparing nano-copper powder is characterized in that the mass ratio of the copper salt to deionized water in step 1 is 1:6-10. The present invention obtains copper nanoparticles with controllable particle size by reasonably and effectively controlling the concentration of the copper salt. Too high a concentration is not conducive to particle size control, and too low a solution concentration is not conducive to industrial production.

[0008] The above-mentioned method for preparing nano-copper powder is characterized in that the additive in step 2 is one or more of sodium alginate, L-methionine, betaine, and glycine. The present invention controls the reducing agent A to ensure that it can coordinate or cross-link with copper ions, effectively controlling the concentration of copper ions in the solution, facilitating the control of the particle size of the nano-copper powder, and the additive also helps the product obtain a spherical morphology.

[0009] The above-mentioned method for preparing nano-copper powder is characterized in that the reducing agent A in step 2 is one or more of maltose, fructose, and galactose. By controlling the composition of the reducing agent A, the present invention ensures that copper seed crystals are obtained first, providing crystal nuclei for subsequent copper crystal growth.

[0010] The above-mentioned method for preparing nano-copper powder is characterized in that the mass ratio of the additive to reducing agent A in step 2 is 1:100-150, the molar ratio of reducing agent A to copper salt is 2-3:1, and the concentration of reducing agent A in the solution prepared by the additive and reducing agent A is 1M. By controlling the ratio of the additive, reducing agent A, and copper salt, the present invention effectively regulates the amount of reducing agent used and the reaction rate, thereby obtaining nano-copper powder of a desired particle size.

[0011] The above-mentioned method for preparing nano copper powder is characterized in that the reducing agent C in step 4 is hydroxylamine hydrochloride, benzoic acid or hyaluronic acid. The present invention controls the composition of the reducing agent C to fully carry out the reduction reaction.

[0012] The above-mentioned method for preparing nano-copper powder is characterized in that the molar ratio of the reducing agent C to the copper salt in step 4 is 1 to 1.5:1, and the reducing agent C is added dropwise. By controlling the molar ratio of the reducing agent C to the copper salt, the present invention ensures that the reduction reaction proceeds fully. Moreover, by adding the reducing agent C dropwise, the concentration of the reducing agent in the reaction system is effectively controlled, allowing the reaction to proceed slowly, thereby avoiding the problem of uneven particle size distribution caused by excessively high reducing agent concentration in the system at one time, which makes it difficult to control the product particle size.

[0013] The aforementioned method for preparing nano-copper powder is characterized in that the heating rate of the oven in step 5 to 90°C to 120°C is no greater than 5°C / min. By controlling the heating rate to meet the required reaction temperature and achieve a slow temperature increase in the system, the nucleation reaction in the system is controlled at a constant rate, thereby ensuring uniform product particle size.

[0014] The above-mentioned method for preparing nano copper powder is characterized in that the vacuum drying temperature in step 6 is 50° C. to 80° C. The present invention ensures that the nano copper powder is fully dried and avoids oxidation by controlling the vacuum drying temperature.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The present invention proposes to use a liquid phase chemical reduction method to effectively regulate the crystal nucleation and growth rate through a two-step reaction, thereby obtaining a nano copper powder with a particle size of 80nm~100nm, uniform size, and certain antioxidant ability.

[0016] 2. The present invention adopts a two-step control method, first allowing copper ions to act on the additive and reducing agent A at the same time. On the one hand, since reducing agent A is a weak reducing agent, when reacting with copper ions, it can effectively control the rate of crystal nucleation, prevent rapid crystal nucleation and anisotropic growth, and ensure that the obtained copper crystal nuclei are uniform in size; on the other hand, copper ions can undergo bonding and coordination with the carboxyl groups in the additive, which can effectively reduce the oxidation of the generated copper seeds by dissolved oxygen in the solution or air. At the same time, under the influence of the steric hindrance effect, it can also prevent the occurrence of seed agglomeration. Therefore, the size of the obtained nucleated seeds is controllable and uniform, which provides a good nucleation basis for the subsequent crystal growth. Subsequently, a certain amount of strong reducing agent is added dropwise, and the copper crystal nuclei are gradually grown by slow dropwise addition, and finally a nano-copper powder with a particle size of 80nm~100nm, uniform size, and antioxidant ability is obtained.

[0017] 3. The present invention addresses the current problems of difficulty in preparing narrow-particle copper powder, poor uniformity in particle size distribution of the obtained small-sized copper powder, high activity of nano-copper powder, and easy oxidation. It adopts a two-step reduction control method to avoid the use of long-chain surfactants such as PVP and CTAB, reduce the residual organic matter on the surface of nano-copper, and effectively improve its own optical, thermal, electrical, and magnetic properties. It breaks through the current technical limitations of severe agglomeration of small-particle nano-copper powder and difficulty in large-scale preparation. The process is simple, operable, and repeatable, and it is a new method for preparing small-particle, narrow-distribution, and antioxidant nano-copper powder materials.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a high-magnification SEM image of the nano-copper powder prepared in Example 1 of the present invention.

[0020] Figure 2 This is a low-magnification SEM image of the nano-copper powder prepared in Example 1 of the present invention.

[0021] Figure 3 3 is a SEM image of the nano copper powder prepared in Example 2 of the present invention.

[0022] Figure 4 This is a SEM image of the nano copper powder prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0023] Example 1 This embodiment includes the following steps: Step 1: Dissolve 100 g of copper nitrate trihydrate in 600 mL of deionized water and stir to obtain a clear blue solution. Step 2: Take 0.85 mol of maltose, add 850 mL of deionized water, dissolve and stir completely, then add 3 g of L-methionine to prepare a solution; Step 3: adding the solution prepared in step 2 to the blue clear solution obtained in step 1 to obtain a brown mixed solution B; Step 4: Add 0.41 mol of hydroxylamine hydrochloride dropwise to the mixed solution B obtained in step 3 to obtain a mixed solution D; Step 5: Place the mixed solution D obtained in step 4 into a reaction kettle, and then heat it to 90°C in an oven at a heating rate of 5°C / min and react for 1 hour to obtain a purple-red product; Step 6: Wash the purple-red product obtained in step 5 with deionized water and anhydrous ethanol three times in sequence, and dry it in a vacuum drying oven at 50° C. for 10 h to obtain nano-copper powder with a particle size of 100 nm.

[0024] Figure 1 This is a high-magnification SEM image of the nano copper powder prepared in this embodiment. Figure 2 This is a low-magnification SEM image of the nano copper powder prepared in this embodiment. Figure 1 and Figure 2 It can be seen that the nano copper powder prepared in this embodiment is nanoparticles with a particle size distribution of about 100 nm, uniform size, clean surface, and no obvious coating. In addition to the particle morphology, no other morphology or impurity products appear in the nano copper powder prepared in this embodiment, indicating that the obtained nano copper powder has high purity.

[0025] Example 2 This embodiment includes the following steps: Step 1: Dissolve 100 g of copper acetate monohydrate in 1 L of deionized water and stir to obtain a clear blue solution. Step 2: Take 1.5 mol of fructose, add 1.5 L of deionized water, dissolve and stir completely, then add 1.8 g of sodium alginate to prepare a solution; Step 3: adding the solution prepared in step 2 to the blue clear solution obtained in step 1 to obtain a brown mixed solution B; Step 4: adding 0.75 mol of hyaluronic acid dropwise to the mixed solution B obtained in step 3 to obtain a mixed solution D; Step 5: Place the mixed solution D obtained in step 4 in a reaction kettle, and then heat it to 120°C in an oven at a heating rate of 5°C / min and react for 5 hours to obtain a purple-red product; Step 6: Wash the purple-red product obtained in step 5 with deionized water and anhydrous ethanol three times in sequence, and dry it in a vacuum drying oven at 50° C. for 10 h to obtain nano-copper powder with a particle size of 80 nm.

[0026] Figure 3 This is the SEM image of the nano copper powder prepared in this embodiment. Figure 3 It can be seen that the nano copper powder prepared in this embodiment has a granular structure with a particle size of about 80 nm, a uniform particle size distribution, and uniform size. In addition to copper nanoparticles, the nano copper powder prepared in this embodiment does not have other morphologies and other impurity products, indicating that the obtained nano copper powder has a high purity.

[0027] Example 3 This embodiment includes the following steps: Step 1: Dissolve 200 g of copper sulfate pentahydrate in 1.6 L of deionized water and stir to obtain a clear blue solution. Step 2: Take 2 mol of glucose, add 2 L of deionized water, dissolve and stir completely, then add 2 g of L-methionine and 1 g of glycine to prepare a solution; Step 3: adding the solution prepared in step 2 to the blue clear solution obtained in step 1 to obtain a brown mixed solution B; Step 4: Add 1 mol of hydroxylamine hydrochloride dropwise to the mixed solution B obtained in step 3 to obtain a mixed solution D; Step 5: Place the mixed solution D obtained in step 4 in a reaction kettle, and then heat it to 100°C in an oven at a heating rate of 5°C / min and react for 3 hours to obtain a purple-red product; Step 6: Wash the purple-red product obtained in step 5 with deionized water and anhydrous ethanol four times in sequence, and dry it in a vacuum drying oven at 80° C. for 8 h to obtain nano-copper powder with a particle size of 100 nm.

[0028] Figure 4 This is the SEM image of the nano copper powder prepared in this embodiment. Figure 4 It can be seen that the nano copper powder prepared in this embodiment has a granular structure with a particle size of about 100 nm, a uniform particle size distribution, and uniform size. In addition to copper nanoparticles, the nano copper powder prepared in this embodiment does not have other morphologies and other impurity products, indicating that the obtained nano copper powder has a high purity.

[0029] Example 4 This embodiment includes the following steps: Step 1: Dissolve 100g of copper chloride dihydrate in 1L of deionized water and stir to obtain a clear blue solution; Step 2: Take 1 mol of fructose and 0.5 mol of glucose, add 1.5 L of deionized water, dissolve and stir completely, then add 2.25 g of sodium alginate to prepare a solution; Step 3: adding the solution prepared in step 2 to the blue clear solution obtained in step 1 to obtain a brown mixed solution B; Step 4: adding 0.7 mol of hyaluronic acid dropwise to the mixed solution B obtained in step 3 to obtain a mixed solution D; Step 5: Place the mixed solution D obtained in step 4 into a reaction kettle, and then heat it to 110°C in an oven at a heating rate of 5°C / min and react for 5 hours to obtain a purple-red product; Step 6: Wash the purple-red product obtained in step 5 with deionized water and anhydrous ethanol three times in sequence, and dry it in a vacuum drying oven at 50° C. for 10 h to obtain nano-copper powder with a particle size of 90 nm.

[0030] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing nano copper powder, characterized in that: The method comprises the following steps: Step 1: Dissolve copper salt in deionized water and stir evenly to obtain a blue clear solution; Step 2: preparing a solution with the additive and reducing agent A; Step 3: adding the solution prepared by the additive and reducing agent A in step 2 to the blue clear solution obtained in step 1 to obtain a mixed solution B; Step 4: Add reducing agent C to the mixed solution B obtained in step 3 and stir evenly to obtain a mixed solution D; Step 5: Place the mixed solution D obtained in step 4 into a reaction kettle, and then react in an oven at 90°C to 120°C for 1h to 5h to obtain a purple-red product; Step 6: The purple-red product obtained in step 5 is washed with deionized water and anhydrous ethanol in sequence, and vacuum-dried to obtain nano-copper powder with a particle size of 80 nm to 100 nm.

2. The method for preparing nano copper powder according to claim 1, wherein The copper salt in step 1 is copper nitrate trihydrate, copper sulfate pentahydrate, copper chloride dihydrate or copper acetate monohydrate.

3. The method for preparing nano copper powder according to claim 1, wherein The mass ratio of the copper salt to deionized water in step 1 is 1:6~10.

4. The method for preparing nano copper powder according to claim 1, wherein: The additive in step 2 is one or more of sodium alginate, L-methionine, betaine and glycine.

5. The method for preparing nano copper powder according to claim 1, wherein: The reducing agent A in step 2 is one or more of maltose, fructose and galactose.

6. The method for preparing nano copper powder according to claim 1, wherein: In step 2, the mass ratio of the additive to the reducing agent A is 1:100-150, and the molar ratio of the reducing agent A to the copper salt is 2-3:1; the concentration of the reducing agent A in the solution prepared by the additive and the reducing agent A is 1M.

7. The method for preparing nano copper powder according to claim 1, wherein: The reducing agent C in step 4 is hydroxylamine hydrochloride, benzoic acid or hyaluronic acid.

8. The method for preparing nano copper powder according to claim 1, wherein: In step 4, the molar ratio of the reducing agent C to the copper salt is 1-1.5:1, and the reducing agent C is added dropwise.

9. The method for preparing nano copper powder according to claim 1, wherein: In step 5, the oven is heated to 90°C-120°C at a rate not exceeding 5°C / min.

10. The method for preparing nano copper powder according to claim 1, wherein: The vacuum drying temperature in step 6 is 50°C to 80°C.

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