Preparation method of silver-coated copper powder and post-processing method thereof

Abstract

The present invention discloses a preparation method of silver-coated copper powder and a post-treatment method thereof, and relates to the technical field of metal powder metallurgy. The present invention proposes a two-step method for preparing densely coated silver-coated copper powder. After copper powder is mixed with a silver nitrate solution, a reduction reaction occurs in the first step, and the surface of the copper powder is partially coated with silver, but the silver layer is incomplete, and there are some exposed copper areas. In the second step, a reducing agent is added to promote the reduction reaction of the silver nitrate solution. Since there are many micron-sized copper powders in the reaction solution, the growth mode of silver tends to be heterogeneous nucleation, adsorbed on the surface of the copper powder, and further silver-plated on the exposed copper areas, thereby achieving the coating of the copper powder with a dense silver layer. The silver plating layer of the micro-nano-sized silver-coated copper powder is dense, completely coated, has low resistivity, and has excellent oxidation resistance and electrical conductivity. In addition, the method is simple and easy to mass-produce, is environmentally friendly, and is conducive to sewage treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of metal powder metallurgy, in particular to the technical field of silver-coated copper powder, and more specifically to a preparation method of silver-coated copper powder and a post-processing method thereof. Background Art

[0002] Silver powder has excellent conductivity, and its oxides still have good conductivity. It is widely used in photovoltaics, 5G communications, flexible displays, and other fields. It is the main component of conductive pastes, but silver powder is expensive. Copper powder, on the other hand, is a perfect substitute for silver powder due to its low price and good conductivity. However, copper is not resistant to high temperatures and is easily oxidized. The high content of copper oxide on the surface of copper powder greatly reduces its conductivity and limits its application in conductive pastes. Some researchers have proposed coating the copper powder with a layer of conductive and antioxidant silver to form a core-shell structure. Coating the copper powder with silver powder solves the problem of copper's easy oxidation while maintaining the anti-migration properties of silver. At the same time, it is low-cost, making it an ideal alternative to silver powder with broad application prospects.

[0003] Currently, the main methods for preparing silver-coated copper powder include chemical reduction, mixed ball milling, and melt atomization. Chemical reduction methods primarily include chemical reduction, displacement, and a combination of displacement and deposition. Chemical methods are currently the most commonly used to prepare micro-nanoscale silver-coated copper powder. However, several unresolved issues remain with chemical methods for preparing micro-nanoscale silver-coated copper powder. Patent CN201210440784.0 utilizes a displacement principle to prepare silver-coated copper powder, but its thermogravimetric curve shows weight gain at high temperatures, indicating a low coverage rate. Patent CN 106794516 B utilizes a chemical reduction method to prepare silver-coated copper powder. However, to ensure complete coating, a toxic potassium gold cyanide solution is used, requiring more stringent wastewater post-treatment and causing increased environmental pollution. Incomplete silver coating and soft agglomeration of copper powder prevent the formation of a dense silver layer. Coating defects also exist on the copper powder surface, resulting in low antioxidant capacity and reduced electrical conductivity. Therefore, how to prepare micro-nano silver-coated copper powder with complete coating, low resistivity, excellent oxidation resistance and conductivity has become an urgent problem that needs to be solved in this field. Summary of the Invention

[0004] To overcome the defects and shortcomings of the above-mentioned prior art, the present invention provides a method for preparing silver-coated copper powder and a post-treatment method thereof. The present invention aims to address the problem of coating defects on the surface of existing copper powder, resulting in low oxidation resistance and reduced electrical conductivity. The present invention proposes a two-step method for preparing densely coated silver-coated copper powder. After mixing copper powder with a silver nitrate solution, a reduction reaction occurs in the first step, partially coating the copper powder surface with silver. However, the silver layer is incomplete, leaving some exposed copper areas. In the second step, a reducing agent is added to promote the reduction reaction of the silver nitrate solution. Due to the presence of a large amount of micron-sized copper powder in the reaction solution, the silver growth pattern tends to be heterogeneous nucleation, adsorbing onto the copper powder surface. Further silver plating is performed on the exposed copper areas, achieving a dense silver layer coating the copper powder. The silver-coated micro-nanoscale copper powder has a dense, fully coated silver layer with low resistivity and excellent oxidation resistance and electrical conductivity. Furthermore, the method is simple and easy to mass produce, environmentally friendly, and beneficial for wastewater treatment.

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention is achieved through the following technical solutions:

[0006] A first aspect of the present invention provides a method for preparing silver-coated copper powder, the method comprising the following steps:

[0007] S1. Pretreatment of micro-nano copper powder: sodium hydroxide and ammonia solution are sequentially added to the copper powder, and ultrasonic stirring is performed to remove organic matter and copper oxide on the surface of the copper powder;

[0008] S2. Preparation of copper powder precursor: The pretreated copper powder is uniformly mixed with a complexing agent and a dispersant in a molar ratio of 100:2:1 to prepare a copper powder precursor. The concentration of the copper powder precursor is 0.3 mol / L-2 mol / L.

[0009] S3, preparation of silver nitrate solution: silver nitrate and a complexing agent are prepared in a molar ratio of 1:1 to form a silver nitrate solution with a concentration of 0.3 mol / L-2 mol / L, and the mass ratio of silver nitrate to copper powder is 100:16-100:63.4; the complexing agent used in this step is the same as the complexing agent in step S2;

[0010] S4, preparation of silver-coated copper powder: adding the silver nitrate solution in S3 dropwise to the solution obtained in step S2 at a pump speed of 100 ml / min-500 ml / min to perform the first silver plating reaction;

[0011] S5. Prepare 50ml-200ml of a reducing agent solution with a concentration of 0.01mol / L-0.1mol / L, and add it dropwise to the solution in step S4 at a speed of 10ml / min-100ml / min. Perform the second silver plating reaction based on step S4.

[0012] Preferably, the complexing agent in step S2 comprises any one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, iminodiacetic acid, diethylenetriamine and triethylenediamine, or a mixture of two thereof.

[0013] Preferably, the dispersant in step S2 comprises any one of ammonium carbonate, gum arabic, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, gelatin, histidine and proline, or a mixture of two thereof.

[0014] The reducing agent in step S5 includes any one of ascorbic acid, formalin, hydrazine hydrate, glucose and hydroxylamine hydrochloride, or a mixture of two thereof.

[0015] A second aspect of the present invention provides a post-treatment method for silver-coated copper powder, which comprises first coating the silver-coated copper powder with 0.3wt%-0.6wt% of an organic acid modifier, adding 5g of ammonia water and stirring evenly, and then adding 0.2wt%-0.4wt% of an organic amine modifier for coating.

[0016] The organic acid modifier is any one of oleic acid, linoleic acid, oleic acid, acetic acid, palmitic acid, myristic acid, polyacrylic acid, triglyceride, palmitic acid, stearic acid, linolenic acid, succinic acid, benzotriazole, benzimidazole, tartaric acid, glyceric acid, hydroxypropionic acid, hydroxymalonic acid, succinic acid and malic acid, or a mixture of two or more thereof.

[0017] The organic amine modifier is any one of diethylamine, diisopropylamine, isobutylamine, hexamethylenediamine, distearylamine, triethylamine, 1,2-dimethylpropylamine, trioctylamine, sec-butylamine, ethylenediamine and diethanolamine, or a mixture of two or more thereof.

[0018] Compared with the prior art, the beneficial technical effects brought about by the present invention are as follows:

[0019] 1. The present invention proposes a two-step method for preparing densely coated silver-coated copper powder. After mixing copper powder with silver nitrate solution, a reduction reaction occurs in the first step, and the surface of the copper powder is partially coated with silver, but the silver layer is incomplete, and there are some exposed copper areas. In the second step, a reducing agent is added to promote the reduction reaction of the silver nitrate solution. Since there are many micron-sized copper powders in the reaction solution, the growth mode of silver tends to be heterogeneous nucleation, adsorbed on the surface of the copper powder, and further silver-plated on the exposed copper areas, achieving the coating of the copper powder with a dense silver layer. The silver plating layer of the micro-nano-sized silver-coated copper powder is dense, completely coated, has low resistivity, and has excellent oxidation resistance and conductivity. In addition, this method is simple and easy to mass-produce, is environmentally friendly, and is conducive to sewage treatment.

[0020] 2. The preparation method provided by the present invention has a simple process, high silver atom utilization rate, no need for heating, and is easy to mass produce; the silver plating layer of the micron-sized silver-coated copper powder provided by the present invention is dense, completely coated, has low resistivity, and good antioxidant performance; the micro-nano silver-coated copper powder provided by the present invention has excellent dispersibility.

[0021] 3. The post-treatment method of the present invention first coats the silver-coated copper powder with an organic acid modifier, then adds ammonia water to adjust the potential, and then adds an organic amine modifier for coating. An amide bond is formed between the organic acid and the organic amine, thereby achieving the purpose of modification and preventing the silver-coated copper powder from hard adhesion. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain examples of the present invention and should not be regarded as limiting the scope.

[0023] Figure 1 This is a scanning electron microscope (SEM) image of the silver-coated copper powder of Example 1;

[0024] Figure 2 This is a scanning electron microscope (SEM) image of the silver-coated copper powder of Example 2;

[0025] Figure 3 This is a scanning electron microscope (SEM) image of pure copper powder;

[0026] Figure 4 This is the XRD diffraction pattern of silver-coated copper powder;

[0027] Figure 5 is the particle size distribution curve of silver-coated copper powder. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0029] Example 1

[0030] As a preferred embodiment of the present invention, this embodiment discloses a method for preparing silver-coated copper powder, comprising the following steps:

[0031] (1) Pretreatment of micro-nano copper powder: 10 g of copper powder was ultrasonically dispersed in a 2 mol / L sodium hydroxide solution and stirred for 5 min. The solid-liquid separation was then performed, and the copper powder was taken out and dispersed in a 20 ml ammonia solution and stirred for 5 min to remove organic matter and copper oxide on the surface of the copper powder. The copper powder was filtered out and washed 4 times.

[0032] (2) Preparation of copper powder precursor: 11.26 g of ethylenediaminetetraacetic acid and 0.15 g of ammonium carbonate were dissolved in 150 g of pure water, and the copper powder prepared in step (1) was dispersed in the solution to prepare solution A, which was kept warm at 30°C.

[0033] (3) Preparation of silver nitrate solution: Dissolve 3 g of ethylenediaminetetraacetic acid in 120 g of pure water, add 1.6 g of silver nitrate to the solution, stir evenly, and keep the resulting solution B at 30°C;

[0034] (4) Preparation of silver-coated copper powder: Solution B was added dropwise to Solution A at a pump speed of 400 ml / min, while stirring Solution A at a stirring speed of 250 r / min. The stirring reaction was maintained at a water bath temperature of 30°C for 2 min. Then, 10 ml of 0.1 mol / L ascorbic acid solution was prepared and added dropwise to the reaction solution at a dropping speed of 30 ml / min to promote the reaction.

[0035] (5) The reaction solution was transferred to a vacuum filter and the obtained powder was washed 5 times. Then, 0.03 g of lauric acid was weighed and dissolved in 5 ml of anhydrous ethanol. The washed silver-coated copper powder was added and stirred at 300 r / min for 15 min. Then, 5 g of ammonia water was added, and then 0.03 g of ethylenediamine alcohol solution was added. The mixture was stirred at 300 r / min for 30 min. The excess ethanol was removed by filtration to obtain silver-coated copper powder.

[0036] Example 2

[0037] As another preferred embodiment of the present invention, this embodiment discloses a method for preparing silver-coated copper powder, comprising the following steps:

[0038] (1) Pretreatment of micro-nano copper powder: 10 g of copper powder was ultrasonically dispersed in a 2 mol / L sodium hydroxide solution and stirred for 5 min. The solid-liquid separation was then performed, and the copper powder was taken out and dispersed in a 20 ml ammonia solution and stirred for 5 min to remove organic matter and copper oxide on the surface of the copper powder. The copper powder was filtered out and washed 4 times.

[0039] (2) Preparation of copper powder precursor: 11.26 g of ethylenediaminetetraacetic acid and 0.15 g of ammonium carbonate were dissolved in 150 g of pure water, and the copper powder prepared in step (1) was dispersed in the solution to prepare solution A, which was kept warm at 30°C.

[0040] (3) Preparation of silver nitrate solution: Dissolve 3 g of ethylenediaminetetraacetic acid in 120 g of pure water, add 6.43 g of silver nitrate to the solution, stir evenly, and keep the resulting solution B at 30°C;

[0041] (4) Preparation of silver-coated copper powder: Solution B was added dropwise to Solution A at a pump speed of 400 ml / min, while stirring Solution A at a stirring speed of 250 r / min. The stirring reaction was maintained at a water bath temperature of 30°C for 2 min. Then, 10 ml of 0.1 mol / L ascorbic acid solution was prepared and added dropwise to the reaction solution at a dropping speed of 30 ml / min to promote the reaction.

[0042] (5) The reaction solution was transferred to a vacuum filter and the obtained powder was washed 5 times. Then, 0.03 g of lauric acid was weighed and dissolved in 5 ml of anhydrous ethanol. The washed silver-coated copper powder was added and stirred at 300 r / min for 15 min. Then, 5 g of ammonia water was added, and then 0.03 g of ethylenediamine alcohol solution was added. The mixture was stirred at 300 r / min for 30 min. The excess ethanol was removed by filtration to obtain silver-coated copper powder.

[0043] The silver-coated copper powder obtained in Example 1 and Example 2 was compared with the pure copper powder by electron microscope. Figure 1 、 Figure 2 、 Figure 3 As shown, through the electron microscope images of Example 1, Example 2, and pure copper powder, it can be seen that the surface of the pure copper powder is rough, and the surface edge is smooth after the silver coating is achieved, as shown in FIG. Figure 4 and Figure 5 As shown, in the XRD diffraction pattern, it can be seen that the diffraction peak of copper appears in Example 1, indicating that the copper powder has not been completely coated and there is a problem of copper leakage. The diffraction peaks of Example 2 are all silver, proving that complete coating can be achieved under this condition, thereby forming a complete silver-coated copper powder.

[0044] Example 3

[0045] As another preferred embodiment of the present invention, this embodiment discloses a method for preparing silver-coated copper powder, comprising the following steps:

[0046] (1) Pretreatment of micro-nano copper powder: 10 g of copper powder was ultrasonically dispersed in a 2 mol / L sodium hydroxide solution and stirred for 5 min. The solid-liquid separation was then performed, and the copper powder was taken out and dispersed in a 20 ml ammonia solution and stirred for 5 min to remove organic matter and copper oxide on the surface of the copper powder. The copper powder was filtered out and washed 4 times.

[0047] (2) Preparation of copper powder precursor: 11.26 g of ethylenediaminetetraacetic acid and 0.15 g of ammonium carbonate were dissolved in 150 g of pure water, and the copper powder prepared in step (1) was dispersed in the solution to prepare solution A, which was kept warm at 30°C.

[0048] (3) Preparation of silver nitrate solution: Dissolve 3 g of ethylenediaminetetraacetic acid in 120 g of pure water, add 6.43 g of silver nitrate to the solution, stir evenly, and keep the resulting solution B at 30°C;

[0049] (4) Preparation of silver-coated copper powder: Solution A and Solution B were stirred and mixed, and the reaction was stirred for 2 min in a water bath at 30°C. Then, 50 ml of 0.1 mol / L glucose solution was prepared and added dropwise to the reaction solution at a rate of 30 ml / min to promote the reaction.

[0050] (5) The reaction solution was transferred to a vacuum filter and the obtained powder was washed 5 times. Then, 0.07 g of lauric acid was weighed and dissolved in anhydrous ethanol. The washed silver-coated copper powder was added and stirred for 15 min. Then, 5 g of ammonia water was added, followed by an alcohol solution of ethylenediamine. The mixture was stirred at high speed for 30 min. The excess ethanol was removed by filtration to obtain silver-coated copper powder.

[0051] Example 4

[0052] As another preferred embodiment of the present invention, this embodiment discloses a method for preparing silver-coated copper powder, comprising the following steps:

[0053] (1) Pretreatment of micro-nano copper powder: 10 g of copper powder was ultrasonically dispersed in a 2 mol / L sodium hydroxide solution and stirred for 5 min. The solid-liquid separation was then performed, and the copper powder was taken out and dispersed in a 20 ml ammonia solution and stirred for 5 min to remove organic matter and copper oxide on the surface of the copper powder. The copper powder was filtered out and washed 4 times.

[0054] (2) Preparation of copper powder precursor: 11.26 g of ethylenediaminetetraacetic acid and 0.15 g of ammonium carbonate were dissolved in 150 g of pure water, and the copper powder prepared in step (1) was dispersed in the solution to prepare solution A, which was kept warm at 30°C.

[0055] (3) Preparation of silver nitrate solution: Dissolve 3 g of ethylenediaminetetraacetic acid in 120 g of pure water, add 6.43 g of silver nitrate to the solution, stir evenly, and keep the resulting solution B at 30°C;

[0056] (4) Preparation of silver-coated copper powder: Solution B was added dropwise to Solution A at a pump speed of 400 ml / min, while stirring Solution A at a stirring speed of 250 r / min. The stirring reaction was maintained at a water bath temperature of 30°C for 2 min. Then, 10 ml of 0.1 mol / L ascorbic acid solution was prepared and added dropwise to the reaction solution at a dropping speed of 30 ml / min to promote the reaction.

[0057] (5) The reaction solution was transferred to a vacuum filter and the obtained powder was washed 5 times. Then, 0.03 g of polyacrylic acid was weighed and dissolved in 5 ml of anhydrous ethanol. The washed silver-coated copper powder was added and stirred at 300 r / min for 15 min. Then, 5 g of ammonia water was added, and then 0.03 g of ethylenediamine alcohol solution was added. The stirring was continued at 300 r / min for 30 min. The excess ethanol was removed by filtration to obtain silver-coated copper powder.

[0058] Example 5

[0059] As another preferred embodiment of the present invention, this embodiment discloses a method for preparing silver-coated copper powder, the preparation method comprising the following steps:

[0060] S1. Pretreatment of micro-nano copper powder: sodium hydroxide and ammonia solution are sequentially added to the copper powder, and ultrasonic stirring is performed to remove organic matter and copper oxide on the surface of the copper powder;

[0061] S2. Preparation of copper powder precursor: The pretreated copper powder is uniformly mixed with a complexing agent and a dispersant in a molar ratio of 100:2:1 to prepare a copper powder precursor. The concentration of the copper powder precursor is 0.3 mol / L.

[0062] S3, preparation of silver nitrate solution: silver nitrate and complexing agent are prepared in a molar ratio of 1:1 to form a silver nitrate solution with a concentration of 0.3 mol / L, and the mass ratio of silver nitrate to copper powder is 100:16; the complexing agent used in this step is the same as the complexing agent in step S2;

[0063] S4, preparation of silver-coated copper powder: adding the silver nitrate solution in S3 dropwise to the solution obtained in step S2 at a pump speed of 100 ml / min to perform the first silver plating reaction;

[0064] S5. Prepare 50 ml of a reducing agent solution with a concentration of 0.1 mol / L, and add it dropwise to the solution in step S4 at a rate of 10 ml / min. Perform a second silver plating reaction based on step S4.

[0065] Among them, the complexing agent in step S2 can be selected from any one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, iminodiacetic acid, diethylenetriamine and triethylenediamine, or a mixture of two of them; the dispersant includes any one of ammonium carbonate, gum arabic, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, gelatin, histidine and proline, or a mixture of two of them; the reducing agent includes any one of ascorbic acid, formalin, hydrazine hydrate, glucose and hydroxylamine hydrochloride, or a mixture of two of them.

[0066] Example 6

[0067] As another preferred embodiment of the present invention, this embodiment discloses a method for preparing silver-coated copper powder, the preparation method comprising the following steps:

[0068] S1. Pretreatment of micro-nano copper powder: sodium hydroxide and ammonia solution are sequentially added to the copper powder, and ultrasonic stirring is performed to remove organic matter and copper oxide on the surface of the copper powder;

[0069] S2. Preparation of copper powder precursor: The pretreated copper powder is uniformly mixed with a complexing agent and a dispersant in a molar ratio of 100:2:1 to prepare a copper powder precursor. The concentration of the copper powder precursor is 1 mol / L.

[0070] S3, preparation of silver nitrate solution: silver nitrate and complexing agent are prepared in a molar ratio of 1:1 to form a silver nitrate solution with a concentration of 1 mol / L, and the mass ratio of silver nitrate to copper powder is 100:30; the complexing agent used in this step is the same as the complexing agent in step S2;

[0071] S4, preparation of silver-coated copper powder: adding the silver nitrate solution in S3 to the solution obtained in step S2 at a pump speed of 300 ml / min to perform the first step of silver plating reaction;

[0072] S5. Prepare 150 ml of a reducing agent solution with a concentration of 0.05 mol / L, add it dropwise to the solution in step S4 at a speed of 50 ml / min, and perform a second silver plating reaction based on step S4; wherein, the complexing agent in step S2 can be selected from any one or a mixture of two of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, iminodiacetic acid, diethylenetriamine and triethylenediamine; the dispersant includes any one or a mixture of two of ammonium carbonate, gum arabic, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, gelatin, histidine and proline; the reducing agent includes any one or a mixture of two of ascorbic acid, formalin, hydrazine hydrate, glucose and hydroxylamine hydrochloride.

[0073] Example 7

[0074] As another preferred embodiment of the present invention, this embodiment discloses a method for preparing silver-coated copper powder, the preparation method comprising the following steps:

[0075] S1. Pretreatment of micro-nano copper powder: sodium hydroxide and ammonia solution are sequentially added to the copper powder, and ultrasonic stirring is performed to remove organic matter and copper oxide on the surface of the copper powder;

[0076] S2. Preparation of copper powder precursor: The pretreated copper powder is uniformly mixed with a complexing agent and a dispersant in a molar ratio of 100:2:1 to prepare a copper powder precursor. The concentration of the copper powder precursor is 2 mol / L.

[0077] S3, preparation of silver nitrate solution: silver nitrate and complexing agent are prepared in a molar ratio of 1:1 to form a silver nitrate solution with a concentration of 2 mol / L, and the mass ratio of silver nitrate to copper powder is 100:63.4; the complexing agent used in this step is the same as the complexing agent in step S2;

[0078] S4, preparation of silver-coated copper powder: adding the silver nitrate solution in S3 dropwise to the solution obtained in step S2 at a pump speed of 500 ml / min to perform the first step of silver plating reaction;

[0079] S5. Prepare 200 ml of a reducing agent solution with a concentration of 0.01 mol / L, add it dropwise to the solution in step S4 at a rate of 100 ml / min, and perform a second silver plating reaction based on step S4; wherein, the complexing agent in step S2 can be selected from any one or a mixture of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, iminodiacetic acid, diethylenetriamine and triethylenediamine; the dispersant includes any one or a mixture of ammonium carbonate, gum arabic, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, gelatin, histidine and proline; the reducing agent includes any one or a mixture of ascorbic acid, formalin, hydrazine hydrate, glucose and hydroxylamine hydrochloride.

[0080] Example 8

[0081] As another preferred embodiment of the present invention, this embodiment is an elaboration of the technical solution of the post-processing method of the silver-coated copper powder prepared in the above-mentioned embodiments 1 to 7. In this embodiment, a post-processing method of the silver-coated copper powder is disclosed, wherein the silver-coated copper powder is first coated with 0.3 wt% of an organic acid modifier, 5 g of ammonia water is added and stirred evenly, and then 0.2 wt% of an organic amine modifier is added for coating; the organic acid modifier is soft oleic acid, linoleic acid, oleic acid, acetic acid, palmitic acid, soybean oil, etc. Any one of myristic acid, polyacrylic acid, triglyceride, palmitic acid, stearic acid, linolenic acid, succinic acid, benzotriazole, benzimidazole, tartaric acid, glyceric acid, hydroxypropionic acid, hydroxymalonic acid, succinic acid and malic acid, or a mixture of two or more thereof; the organic amine modifier is any one of diethylamine, diisopropylamine, isobutylamine, hexamethylenediamine, distearylamine, triethylamine, 1,2-dimethylpropylamine, trioctylamine, sec-butylamine, ethylenediamine and diethanolamine, or a mixture of two or more thereof.

[0082] Example 9

[0083] As another preferred embodiment of the present invention, this embodiment is an elaboration of the technical solution of the post-treatment method of the silver-coated copper powder prepared in the above-mentioned embodiments 1 to 7. In this embodiment, a post-treatment method of the silver-coated copper powder is firstly coated with 0.5wt% of an organic acid modifier, 5g of ammonia water is added and stirred evenly, and then 0.3wt% of an organic amine modifier is added for coating; the organic acid modifier is soft oleic acid, linoleic acid, oleic acid, acetic acid, palmitic acid, cardamom The organic amine modifier is any one of diethylamine, diisopropylamine, isobutylamine, hexamethylenediamine, distearylamine, triethylamine, 1,2-dimethylpropylamine, trioctylamine, sec-butylamine, ethylenediamine and diethanolamine, or a mixture of two or more thereof.

[0084] Example 10

[0085] As another preferred embodiment of the present invention, this embodiment is an elaboration of the technical solution of the post-processing method of the silver-coated copper powder prepared in the above-mentioned embodiments 1 to 7. In this embodiment, a post-processing method of the silver-coated copper powder is firstly coated with 0.6wt% of an organic acid modifier, 5g of ammonia water is added and stirred evenly, and then 0.4wt% of an organic amine modifier is added for coating; the organic acid modifier is soft oleic acid, linoleic acid, oleic acid, acetic acid, palmitic acid, cardamom The organic amine modifier is any one of diethylamine, diisopropylamine, isobutylamine, hexamethylenediamine, distearylamine, triethylamine, 1,2-dimethylpropylamine, trioctylamine, sec-butylamine, ethylenediamine and diethanolamine, or a mixture of two or more thereof.

Claims

1. A method for preparing silver-coated copper powder, characterized in that: The preparation method comprises the following steps: S1. Pretreatment of micro-nano copper powder: sodium hydroxide and ammonia solution are sequentially added to the copper powder, and ultrasonic stirring is performed to remove organic matter and copper oxide on the surface of the copper powder; S2. Preparation of a copper powder precursor: The pretreated copper powder is uniformly mixed with a complexing agent and a dispersant in a molar ratio of 100:2:1 to prepare a copper powder precursor, wherein the concentration of the copper powder precursor is 0.3 mol / L-2 mol / L; the dispersant described in step S2 is ammonium carbonate; the complexing agent described in step S2 includes any one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, iminodiacetic acid, diethylenetriamine and triethylenediamine, or a mixture of two thereof; S3, preparation of silver nitrate solution: silver nitrate and a complexing agent are prepared in a molar ratio of 1:1 to form a silver nitrate solution with a concentration of 0.3 mol / L-2 mol / L, and the mass ratio of silver nitrate to copper powder is 100:16-100:63.4; the complexing agent used in this step is the same as the complexing agent in step S2; S4, preparation of silver-coated copper powder: adding the silver nitrate solution in S3 dropwise to the solution obtained in step S2 at a pump speed of 100 ml / min-500 ml / min to perform the first silver plating reaction; S5. Prepare 50ml-200ml of a reducing agent solution with a concentration of 0.01mol / L-0.1mol / L, and add it dropwise to the solution in step S4 at a speed of 10ml / min-100ml / min. Perform the second silver plating reaction based on step S4.

2. The method for preparing a silver-coated copper powder according to claim 1, wherein: The reducing agent in step S5 includes any one of ascorbic acid, formalin, hydrazine hydrate, glucose and hydroxylamine hydrochloride, or a mixture of two thereof.

3. A post-processing method for the silver-coated copper powder prepared by the preparation method according to claim 1 or 2, characterized in that: First, 0.3wt%-0.6wt% of an organic acid modifier is used to coat the silver-coated copper powder, 5g of ammonia water is added and stirred evenly, and then 0.2wt%-0.4wt% of an organic amine modifier is added for coating.

4. The post-processing method of silver-coated copper powder according to claim 3, wherein: The organic acid modifier is any one of oleic acid, linoleic acid, oleic acid, acetic acid, palmitic acid, myristic acid, polyacrylic acid, triglyceride, palmitic acid, stearic acid, linolenic acid, succinic acid, benzotriazole, benzimidazole, tartaric acid, glyceric acid, hydroxypropionic acid, hydroxymalonic acid, succinic acid and malic acid, or a mixture of two or more thereof.

5. The post-processing method of silver-coated copper powder according to claim 3 or 4, characterized in that: The organic amine modifier is any one of diethylamine, diisopropylamine, isobutylamine, hexamethylenediamine, distearylamine, triethylamine, 1,2-dimethylpropylamine, trioctylamine, sec-butylamine, ethylenediamine and diethanolamine, or a mixture of two or more thereof.

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