Preparation method of micron copper powder

Abstract

The invention belongs to the field of preparation of metal powder, and particularly relates to a preparation method of micron copper powder, which comprises the following steps: reducing a copper salt solution through a reducing agent to prepare copper powder, and adding a dispersing agent, a complexing agent and an auxiliary agent in the reduction process to effectively prevent agglomeration among particles, so that the uniformity of the copper powder is improved. The method for preparing the micron copper powder is simple, economical and reliable, the micron copper powder is prepared in a water solvent, the preparation cost is reduced, the particle size of the prepared copper powder is uniform, the average particle size is about 3 microns, the yield of the copper powder is 95% or above, and the copper powder is high in purity, low in resistivity and good in conductivity.

Description

Technical Field

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

[0002] Copper powder, as an important industrial raw material, is widely used in electronics, chemical industry and other fields. With the advancement of science and technology and the development of industry, higher requirements are placed on the quality, particle size distribution, purity and production cost of copper powder.

[0003] At present, the production methods of copper powder mainly include electrolysis, water atomization, oxidation-reduction and hydrometallurgy. However, in the process of preparing copper powder by reduction method, the controllable synthesis of nano- or micron-sized particles, the selection of additives and the control of reaction conditions are still major challenges.

[0004] Ammonium benzoate can be used as a corrosion inhibitor in metal surface treatment and electroplating processes to form a protective film on the metal surface to prevent metal oxidation; ammonium benzoate is used as an additive in the electroplating process to improve the stability of the electroplating solution; in the process of preparing metal powder by a reduction method, ammonium benzoate is added as an auxiliary agent, and the proportion of ammonium benzoate with a dispersant, a complexing agent, and a reducing agent and the reaction conditions are adjusted to obtain a conductive copper powder with higher purity and better performance. Summary of the invention

[0005] The invention provides a method for preparing micron copper powder. A dispersant, a complexing agent and an auxiliary agent are added during the reduction process, and the micron copper powder with high purity and good conductive performance is obtained by controlling the reaction conditions and proportions.

[0006] The technical solution of the present invention is as follows: A method for preparing micron copper powder, comprising:

[0007] Step 1: Mix a certain amount of copper salt, a complexing agent and a solvent, and heat and mix them evenly to obtain a solution A; the complexing agent forms a copper ammonia complex with the copper ions in the copper salt solution, and the formation of a stable complex helps to prevent the copper ions from reacting with hydroxide ions to generate copper hydroxide precipitation, thereby avoiding the generation of precipitation, and at the same time helps to control the particle size and morphology of the copper powder and improve the dispersibility of the copper powder in the solution.

[0008] Step 2: Mix the reducing agent, complexing agent, dispersant, solvent and auxiliary agent, heat and mix them evenly to obtain solution B; pre-mix the reducing agent, complexing agent, dispersant, solvent and auxiliary agent evenly to provide a stable environment for the subsequent reduction reaction. The uniform reaction conditions are helpful to control the particle size distribution of the copper powder and further enhance the dispersibility of the copper powder.

[0009] Step 3: Mix solution A and solution B evenly, heat the reaction, filter, wash with water, wash with alcohol, and grind to obtain micron copper powder;

[0010] The auxiliary agent is ammonium benzoate.

[0011] The copper salt in step 1 is one or more of anhydrous copper sulfate, copper sulfate pentahydrate, copper nitrate, and copper chloride dihydrate.

[0012] The solvent in step 1 is one or more of distilled water and deionized water.

[0013] The concentration of the solution A is 120-500 g / L; the heating temperature in step 1 is 50-70° C., and the heating time is 0.5-2 h.

[0014] The reducing agent in step 2 is one or more of potassium borohydride, ascorbic acid and sodium hypophosphite.

[0015] The complexing agent is ammonia water, and the ratio of the mass of the copper salt to the volume of the complexing agent is 1g: (0.5mL-5mL).

[0016] In the step 2, the dispersant is one or more of polyvinyl pyrrolidone K15, polyvinyl pyrrolidone K30, polyvinyl pyrrolidone K60 and cyclodextrin.

[0017] The mass ratio of the copper salt, the reducing agent and the dispersing agent is 1:(0.5-2):(1-4.2).

[0018] The mass ratio of the copper salt to ammonium benzoate is 1:0.06-0.125.

[0019] The heating temperature in step 2 is 50-70° C., and the heating time is 0.5-2 h; the heating temperature in step 3 is 80-110° C., and the heating time is 0.5-3 h.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, a dispersant is added during the reduction process. The dispersant can effectively reduce the interaction force between copper powder particles and prevent agglomeration, thereby obtaining a copper powder product with uniform particle size distribution and good dispersibility; it can also improve the surface properties of the copper powder, which helps to improve the activity and reactivity of the copper powder in subsequent applications.

[0022] 2. In the present invention, a complexing agent is added during the reduction process. The complexing agent can form a stable complex with the impurity ions in the solution, thereby effectively removing the impurities; it can also affect the reduction rate of copper ions and the growth of grains.

[0023] 3. The present invention adds an auxiliary agent during the reduction process, and the auxiliary agent is ammonium benzoate. During the reduction process, ammonium benzoate can inhibit the growth of crystal nuclei to a certain extent through adsorption to prevent the particles from being too large; ammonium benzoate can form a protective film on the surface of the copper powder particles, and work together with the dispersant to more effectively prevent the agglomeration of the particles, thereby preparing copper particles with uniform particle size distribution.

[0024] 4. The present invention prepares micron copper powder in a water solvent, which reduces the preparation cost. The particle size of the prepared copper powder is uniform, with an average of about 3 μm, the copper powder yield is above 92%, and the purity is high, with low resistivity and good conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope image of copper powder. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0027] Example 1

[0028] Prepare the copper salt solution to be reduced: weigh 160 g of anhydrous copper sulfate and 150 mL of aqueous ammonia, dissolve them in 600 mL of deionized water, and stir at 60 °C for 1 h.

[0029] Prepare the reducing agent solution: weigh 125 g of sodium hypophosphite, 150 mL of ammonia water, 300 g of cyclodextrin and 15 g of ammonium benzoate, dissolve them in 2400 mL of deionized water, and stir at 60°C for 1 h.

[0030] The stirred copper salt solution to be reduced and the reducing agent solution were mixed together, the reaction temperature was controlled to be 95° C., the reaction time was 1.5 h, and after the reaction was completed, the solution was allowed to stand and precipitate.

[0031] After precipitation is complete, the supernatant is poured out, deionized water is added, stirred and then allowed to stand for precipitation, and this is repeated 6 times. Anhydrous ethanol is then added and this is repeated 2 times. The obtained product is placed in a 55°C vacuum oven and dried for 12 hours. After crushing and grinding, pure micron copper powder is obtained. The scanning electron microscope image of the micron copper powder is shown in FIG. Figure 1 shown.

[0032] Example 2

[0033] Prepare the copper salt solution to be reduced: weigh 160 g of anhydrous copper sulfate and 150 mL of aqueous ammonia, dissolve them in 600 mL of deionized water, and stir at 60 °C for 1 h.

[0034] Prepare the reducing agent solution: weigh 200 g ascorbic acid, 150 mL ammonia water, 250 g polyvinylpyrrolidone K30 and 18 g ammonium benzoate, dissolve them in 2400 mL deionized water, and stir at 60 °C for 1 h.

[0035] The stirred copper salt solution to be reduced and the reducing agent solution were mixed together, the reaction temperature was controlled to be 90° C., the reaction time was 2 h, and after the reaction was completed, the solution was allowed to stand and precipitate.

[0036] After precipitation is complete, pour out the supernatant, add deionized water, stir and let stand to precipitate, repeat 6 times, then add anhydrous ethanol, repeat 2 times, put the obtained product into a 55°C vacuum oven and dry it for 12 hours, and then crush and grind to obtain pure micron copper powder.

[0037] Example 3

[0038] Prepare the copper salt solution to be reduced: weigh 188 g of copper nitrate and 300 mL of ammonia water, dissolve them in 600 mL of deionized water, and stir at 60°C for 0.5 h.

[0039] Prepare the reducing agent solution: weigh 250 g of ascorbic acid, 300 mL of ammonia water, 200 g of polyvinylpyrrolidone K30 and 10 g of ammonium benzoate, dissolve them in 2400 mL of deionized water, and stir at 60°C for 0.5 h.

[0040] The stirred copper salt solution to be reduced and the reducing agent solution are mixed together, the reaction temperature is controlled to be 100° C., the reaction time is 0.5 h, and after the reaction is completed, the mixture is allowed to stand and precipitate.

[0041] After precipitation is complete, pour out the supernatant, add deionized water, stir and let stand to precipitate, repeat 6 times, then add anhydrous ethanol, repeat 2 times, put the obtained product into a 55°C vacuum oven and dry it for 12 hours, and then crush and grind to obtain pure micron copper powder.

[0042] Comparative Example

[0043] Prepare the copper salt solution to be reduced: weigh 160 g of anhydrous copper sulfate and 150 mL of aqueous ammonia, dissolve them in 600 mL of deionized water, and stir at 60 °C for 1 h.

[0044] Prepare the reducing agent solution: weigh 125 g of sodium hypophosphite, 150 mL of ammonia water, and 300 g of cyclodextrin, dissolve them in 2400 mL of deionized water, and stir at 60°C for 1 h.

[0045] The stirred copper salt solution to be reduced and the reducing agent solution were mixed together, the reaction temperature was controlled to be 95° C., the reaction time was 1.5 h, and after the reaction was completed, the solution was allowed to stand and precipitate.

[0046] After precipitation is complete, pour out the supernatant, add deionized water, stir and let stand to precipitate, repeat 6 times, then add anhydrous ethanol, repeat 2 times, put the obtained product into a 55°C vacuum oven and dry it for 12 hours, and then crush and grind to obtain pure micron copper powder.

[0047] The calculation formula for the yield is as follows, where m1 is the actual output of copper powder and m2 is the theoretical output of copper powder.

[0048]

[0049] The copper powders of Examples 1 to 3 and the comparative example were characterized and tested, as shown in Table 1.

[0050] Table 1

[0051]

Claims

1. A method for preparing micron copper powder, characterized in that: include: Step 1: Mix a certain amount of copper salt, a complexing agent and a solvent, and heat and mix them evenly to obtain a solution A; Step 2: Mix the reducing agent, complexing agent, dispersant, solvent and additive, and heat and mix them evenly to obtain solution B; Step 3: Mix solution A and solution B evenly, heat the reaction, filter, wash with water, wash with alcohol, and grind to obtain micron copper powder; The auxiliary agent is ammonium benzoate.

2. The method for preparing micron copper powder according to claim 1, characterized in that: The copper salt in step 1 is one or more of anhydrous copper sulfate, copper sulfate pentahydrate, copper nitrate, and copper chloride dihydrate.

3. The method for determining the chloride ion content in the silver-coated copper powder according to claim 1, wherein: The solvent is one or more of distilled water and deionized water.

4. The method for preparing micron copper powder according to claim 1, characterized in that: The concentration of the solution A is 120-500 g / L; the heating temperature in step 1 is 50-70° C., and the heating time is 0.5-2 h.

5. The method for preparing micron copper powder according to claim 1, characterized in that: The reducing agent in step 2 is one or more of potassium borohydride, ascorbic acid and sodium hypophosphite.

6. The method for preparing micron copper powder according to claim 1, characterized in that: The complexing agent is ammonia water, and the ratio of the mass of the copper salt to the volume of the complexing agent is 1g: (0.5mL-5mL).

7. The method for preparing micron copper powder according to claim 1, characterized in that: In the step 2, the dispersant is one or more of polyvinyl pyrrolidone K15, polyvinyl pyrrolidone K30, polyvinyl pyrrolidone K60 and cyclodextrin.

8. The method for preparing micron copper powder according to claim 1, characterized in that: The mass ratio of the copper salt, the reducing agent and the dispersing agent is 1:(0.5-2):(1-4.2).

9. The method for preparing micron copper powder according to claim 1, characterized in that: The mass ratio of the copper salt to ammonium benzoate is 1:0.06-0.

125.

10. The method for preparing micron copper powder according to claim 1, characterized in that: The heating temperature in step 2 is 50-70° C., and the heating time is 0.5-2 h; the heating temperature in step 3 is 80-110° C., and the heating time is 0.5-3 h.

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