A system and method for synthesizing core-shell structure silver-coated copper powder

Abstract

The application discloses a system and method for synthesizing silver-coated copper powder with a core-shell structure and belongs to the technical field of composite material preparation. The system is composed of a nano-copper core preparation module and a silver-coated copper powder preparation module, and the two modules are directly connected. After the nano-copper core is prepared, the silver coating is directly and continuously performed on the nano-copper core, so that the oxidation problem caused by the contact between the nano-copper core and air is avoided. The nano-copper core preparation process is continuously performed and no operation is needed in the preparation process, parameters are stable, and the batch stability of products is ensured. The silver-coated copper powder preparation system is intermittently operated, the production capacity can be adjusted according to the production capacity of the nano-copper core preparation system, the operation is simple and flexible, and the system is suitable for industrial production. Meanwhile, by arranging a heat recovery system, the supercritical hydrothermal synthesis nano-copper reaction waste heat is used to heat pure water, and the system energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite material preparation system, and particularly relates to a system and method for synthesizing silver-coated copper powder with core-shell structure. BACKGROUND

[0002] The most important performance of silver-coated copper powder is electrical conductivity, which has obvious price advantage compared with silver powder and better electrical conductivity, oxidation resistance and stability compared with copper powder. Therefore, the application of silver-coated copper powder is mainly to replace copper powder and silver powder, and the silver-coated copper powder is specifically used as conductive filler of low-temperature electronic paste and part of high-temperature electronic paste, special paste, printing of circuit board, electrode paste of sheet type multilayer ceramic capacitor, etc., and has wide application range.

[0003] For the synthesis method of silver-coated copper, the chemical reduction method is currently used, and the silver coating is based on the synthesized copper powder. However, since the copper powder is easy to be oxidized, the copper powder needs to be pickled to remove the surface oxide layer before coating, and then the silver coating is performed. The operation process is complicated, the reaction time is long, and the electrical conductivity is not ideal. There is no report on the synthesis system of silver-coated copper at present. The existing experimental system for synthesizing nanomaterials by supercritical hydrothermal method can only synthesize single nanomaterial, and cannot meet the coating demand of silver-coated copper with core-shell structure. SUMMARY

[0004] In order to overcome the defects of the prior art, the purpose of the present application is to provide a system and method for synthesizing silver-coated copper powder with core-shell structure, so as to solve the defects of complicated operation, long reaction time and poor coating effect of the prior art.

[0005] In order to achieve the above purpose, the following technical solutions are adopted in the present application:

[0006] The present application discloses a system for synthesizing silver-coated copper powder with core-shell structure, which is composed of a nano-copper core preparation module and a silver-coated copper powder preparation module.

[0007] The nano-copper core preparation module comprises a pure water conveying unit, a nano-copper raw material conveying unit, a cooler, a heater, a mixing-reactor, a pressure reducer and a gas-liquid separator. The pure water conveying unit is connected with the pure water inlet of the cooler, the pure water outlet of the cooler is connected with the inlet of the heater, the outlet of the heater is connected with the pure water inlet of the mixing-reactor, the nano-copper raw material conveying unit is connected with the raw material inlet of the mixing-reactor, the outlet of the mixing-reactor is connected with the reactant inlet of the cooler, the outlet of the cooler is connected with the inlet of the pressure reducer, the outlet of the pressure reducer is connected with the inlet of the gas-liquid separator, and the liquid phase outlet of the gas-liquid separator is connected with the silver-coated copper powder preparation module.

[0008] The silver-coated copper powder preparation module comprises a coating treatment pool and a solid-liquid separator, the liquid phase outlet of the gas-liquid separator is connected to the coating treatment pool, and a sensitization activator storage tank for conveying a sensitization activator, a dispersant storage tank for conveying a dispersant, and a replacement agent / reducing agent storage tank for conveying a replacement agent / reducing agent are respectively arranged on the coating treatment pool, and the solid-liquid separator is arranged at the bottom of the coating treatment pool.

[0009] Preferably, the pure water conveying unit comprises a pure water storage tank, and a first high-pressure metering pump is arranged on the pipeline connecting the pure water storage tank and the cooler; the nano-copper raw material conveying unit comprises a nano-copper raw material storage tank, and a second high-pressure metering pump is arranged on the pipeline connecting the nano-copper raw material storage tank and the mixing-reactor.

[0010] Preferably, a gas treatment device is arranged at the gas phase outlet of the gas-liquid separator, and is used for treating the gas generated in the synthesis of the nano-copper powder to meet the standard for discharge.

[0011] Preferably, a loop capable of being connected to the inlet end of the embedding treatment pool is further arranged at the bottom of the coating treatment pool, and is used for repeatedly coating the nano-copper core product.

[0012] Preferably, a homogenization device for mixing the reaction materials is arranged in the coating treatment pool, and a heating device for heating the internal reaction materials is arranged outside the coating treatment pool.

[0013] Preferably, the homogenization device adopts a stirrer or an ultrasonic generator, and the heating device adopts a heating jacket or a heating furnace.

[0014] The system for synthesizing the silver-coated copper powder with a core-shell structure disclosed in the application is used for synthesizing the silver-coated copper powder with a core-shell structure based on the above system, and comprises the following steps:

[0015] 1) preparing a nano-copper core

[0016] The pure water is conveyed to the cooler through the pure water conveying unit and then is connected to the mixing-reactor, the nano-copper raw material is conveyed to the mixing-reactor through the nano-copper conveying unit, the pure water and the nano-copper raw material are reacted, the reaction product is sequentially subjected to cooling treatment through the cooler and pressure reduction treatment through the pressure reducer, and then is separated through the gas-liquid separator to obtain a nano-copper powder suspension which is sent to the embedding treatment pool.

[0017] 2) preparing a silver-coated copper powder

[0018] The sensitization activator, the dispersant and the replacement agent / reducing agent are respectively connected to the embedding treatment pool, the nano-copper powder suspension is heated and reacted with the sensitization activator, the dispersant and the replacement agent / reducing agent for 20-60 minutes, the reaction materials are separated through the solid-liquid separator to obtain the silver-coated copper powder with a core-shell structure.

[0019] Preferably, the reaction material is transported to the embedding treatment tank through the loop leading from the bottom of the embedding treatment tank to the inlet end for repeated coating treatment, so as to meet the thickness requirement of the silver coating layer.

[0020] Preferably, the sensitization activator is one or both of stannous chloride solution and palladium chloride solution; and the dispersant is one or more of polyvinylpyrrolidone, polyethylene glycol and sodium dodecyl sulfate.

[0021] Preferably, the displacement agent is one or both of silver nitrate solution and silver ammine solution; and the reducing agent is one or more of formaldehyde, hydrazine hydrate, ascorbic acid, sodium hypophosphite and glucose.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The system for synthesizing silver-coated copper powder with core-shell structure disclosed in the present application is composed of a nano-copper core preparation module and a silver-coated copper powder preparation module, the two modules are directly connected, the nano-copper core is directly and continuously coated with silver after being prepared, the oxidation problem caused by the contact of the nano-copper core with air is avoided, the nano-copper core preparation process is continuously carried out and no operation is required during the preparation process, the parameters are stable, the batch stability of the product is ensured, the silver-coated copper powder preparation system is operated intermittently, the production capacity can be adjusted according to the production capacity of the nano-copper core preparation system, the operation is simple and flexible, and the system is suitable for industrial production. At the same time, after the normal-temperature water passes through the cooler, on the one hand, the temperature of the reaction product in the mixing-reactor is lowered, and on the other hand, the normal-temperature water absorbs the heat of the reaction product, so that the effect of heat recovery is achieved. Therefore, by setting a heat recovery system, the waste heat of the supercritical water heat synthesis of the nano-copper is used to heat the pure water, and the energy consumption of the system is reduced.

[0024] Further, by setting the gas-liquid separator and the gas treatment device, the separation and harmless treatment of the waste gas are realized, and the system is green and pollution-free. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of the system for synthesizing silver-coated copper powder with core-shell structure disclosed in the present application.

[0026] wherein 1 is a pure water storage tank, 2 is a nano-copper raw material storage tank, 3 is a first high-pressure metering pump, 4 is a second high-pressure metering pump, 5 is a heater, 6 is a mixing-reactor, 7 is a cooler, 8 is a pressure reducer, 9 is a gas-liquid separator, 10 is a gas treatment device, 11 is an embedding treatment tank, 12 is a sensitization activator storage tank, 13 is a dispersant storage tank, 14 is a displacement agent / reducing agent storage tank, and 15 is a solid-liquid separator. DETAILED DESCRIPTION

[0027] In order to make the person skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should belong to the protection scope of the present application.

[0028] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0029] The present application will be described in further detail below in conjunction with the drawings:

[0030] Referring to Figure 1 The system for synthesizing core-shell structure silver-coated copper powder disclosed in the present application comprises a nanometer copper synthesis module for synthesizing a nanometer copper core of silver-coated copper powder, including a pure water storage tank 1, an outlet of the pure water storage tank 1 connected to a first high-pressure metering pump 3, an outlet of the first high-pressure metering pump 3 connected to a pure water inlet of a cooler 7, a pure water outlet of the cooler 7 connected to an outlet of a heater 5, the outlet of the heater 5 connected to a pure water inlet of a mixing-reactor 6, further including a nanometer copper raw material storage tank 2, an outlet of the nanometer copper raw material storage tank 2 connected to a second high-pressure metering pump 4, an outlet of the second high-pressure metering pump 4 connected to a raw material inlet of the mixing-reactor 6, an outlet of the mixing-reactor 6 connected to a reactant inlet of the cooler 7, an outlet of the cooler 7 connected to a pressure reducer 8, an outlet of the pressure reducer 8 connected to a gas-liquid separator 9, and a liquid phase outlet of the gas-liquid separator 9 connected to a coating treatment tank 11.

[0031] A silver-coated copper preparation module is used for preparing core-shell structure silver-coated copper powder on the basis of the nanometer copper core, including an outlet of a sensitization activator storage tank 12 connected to the coating treatment tank 11, an outlet of a dispersant storage tank 13 connected to the coating treatment tank 11, an outlet of a displacement agent / reducing agent storage tank 14 connected to the coating treatment tank 11, and an outlet of the coating treatment tank 11 connected to a solid-liquid separator 15.

[0032] A gas phase outlet of the gas-liquid separator 9 is connected to a gas treatment device 10, which is used for treating the gas generated in the synthesis of nanometer copper powder to meet the standard for emission.

[0033] The outlet of the coating treatment tank 11 is provided with a loop connecting the inlet of the coating treatment tank 11 for repeated coating, and the number of times of repeated coating is determined according to the thickness of the silver coating layer required.

[0034] The coating treatment tank 11 is provided with any one or more of a homogenizer, an ultrasonic generator and the like inside, and is provided with a heating device outside for heating the material inside, which can be a heating jacket, a heating furnace and the like.

[0035] Based on the above disclosed silver-coated copper powder system with a core-shell structure, the method for preparing silver-coated copper powder is as follows:

[0036] 1) Prepare the nano-copper core. Pure water is heated by two stages of the cooler 7 and the heater 5, mixed and reacted with the nano-copper raw material in the mixing-reactor 6, cooled by the cooler 7 and depressurized by the pressure reducer 8 after the reaction is completed, and separated by the gas-liquid separator 9 to obtain a nano-copper powder suspension, which is discharged into the coating treatment tank 11;

[0037] 2) Prepare the silver-coated copper powder. Under the condition of strong fluid vibration, the sensitization activator is added from the sensitization activator storage tank 12 to the coating treatment tank 11, the dispersant is added from the dispersant storage tank 13 to the coating treatment tank 11, the displacement agent / reducing agent is added from the displacement agent / reducing agent storage tank 14 to the coating treatment tank 11, and heating is performed, and the reaction is carried out for a period of time.

[0038] Preferably, in order to control the thickness and effect of the silver coating layer, the outlet loop of the coating treatment tank 11 can be controlled for multiple coating.

[0039] Preferably, the sensitization activator is any one or more of stannous chloride solution, palladium chloride solution and the like.

[0040] Preferably, the dispersant is any one or more of polyvinylpyrrolidone, polyethylene glycol, sodium dodecyl sulfate and the like.

[0041] Preferably, silver-coated copper can be synthesized by direct displacement method and chemical reduction method. The displacement agent is any one or more of silver nitrate solution and silver ammonia solution; and the reducing agent is any one or more of formaldehyde, hydrazine hydrate, ascorbic acid, sodium hypophosphite and glucose.

[0042] The synthesis of the silver-coated copper powder system with a core-shell structure is described below by way of examples:

[0043] For the preparation of nano-copper, including pure water storage tank 1, nano-copper raw material storage tank 2, two high-pressure metering pumps 3, 4, heater 5, mixing-reactor 6, cooler 7, pressure reducer 8, gas-liquid separator 9 and gas treatment device 10. Pure water enters the system through high-pressure metering pump 3 and is preheated through the cooler to realize heat circulation and reduce system energy consumption. The precursor in the raw material tank is one of copper sulfate, copper formate and copper nitrate. The pure water heated to the required temperature is fully mixed with the nano-copper raw material in the mixing-reactor and reacts, and then enters the gas-liquid separator through the pressure reducer, the waste gas generated in the experiment is treated, discharged after reaching the standard, and the obtained liquid is the nano-copper suspension. For the preparation of silver-coated copper, the nano-copper suspension is directly added with a sensitizing activator to activate it to prevent the nano-copper from contacting air and being oxidized. The sensitizing activator is stannous chloride solution and palladium chloride solution. The dispersing agent is polyvinylpyrrolidone. Silver-coated copper can be synthesized by chemical reduction method. The displacer is at least one of silver nitrate solution and silver ammine solution, and the reducing agent can be glucose. The obtained silver-coated copper suspension can be coated for multiple times to achieve the expected coating effect and meet different use requirements.

[0044] In summary, the present application discloses a system and method for synthesizing silver-coated copper powder with core-shell structure, which directly connects the nano-copper core preparation system and the silver-coated copper powder preparation system respectively, avoids the oxidation caused by the contact of nano-copper core with air in the process of preparing high-quality silver-coated copper powder; the nano-copper core preparation process is continuous and does not need to be operated during the preparation process, the parameters are stable, which ensures the batch stability of the product, the silver-coated copper powder preparation system is operated intermittently, the production capacity can be adjusted according to the production capacity of the nano-copper core preparation system, the operation is simple and flexible, and it is suitable for industrial production. By setting a heat recovery system, the supercritical water heat synthesis nano-copper reaction waste heat is used to heat pure water, which reduces the system energy consumption; by setting a gas-liquid separator and a gas treatment device, the separation and harmless treatment of waste gas are realized, which is green and pollution-free.

[0045] The above content only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A system for synthesizing core-shell structure silver-coated copper powder, characterized in that, The module is composed of a nano-copper core preparation module and a silver-coated copper powder preparation module. The nano-copper core preparation module comprises a pure water conveying unit, a nano-copper raw material conveying unit, a cooler (7), a heater (5), a mixing-reactor (6), a pressure reducer (8) and a gas-liquid separator (9). The pure water conveying unit is connected with the pure water inlet of the cooler (7). The pure water outlet of the cooler (7) is connected with the inlet of the heater (5). The outlet of the heater (5) is connected with the pure water inlet of the mixing-reactor (6). The nano-copper raw material conveying unit is connected with the raw material inlet of the mixing-reactor (6). The outlet of the mixing-reactor (6) is connected with the reactant inlet of the cooler (7). The outlet of the cooler (7) is connected with the inlet of the pressure reducer (8). The outlet of the pressure reducer (8) is connected with the inlet of the gas-liquid separator (9). The liquid phase outlet of the gas-liquid separator (9) is connected with the silver-coated copper powder preparation module. The silver-coated copper powder preparation module comprises a coating treatment tank (11) and a solid-liquid separator (15). The liquid phase outlet of the gas-liquid separator (9) is connected with the coating treatment tank (11). A sensitization activator storage tank (12) for conveying a sensitization activator, a dispersant storage tank (13) for conveying a dispersant and a replacement agent / reducing agent storage tank (14) for conveying a replacement agent / reducing agent are arranged on the coating treatment tank (11). The solid-liquid separator (15) is arranged at the bottom of the coating treatment tank (11). The replacement agent is one or both of silver nitrate solution and silver ammonia solution.

2. The system for synthesizing core-shell structure copper-coated silver powder according to claim 1, wherein, The pure water conveying unit comprises a pure water storage tank (1). A first high-pressure metering pump (3) is arranged on the pipeline connecting the pure water storage tank (1) and the cooler (7). The nano-copper raw material conveying unit comprises a nano-copper raw material storage tank (2). A second high-pressure metering pump (4) is arranged on the pipeline connecting the nano-copper raw material storage tank (2) and the mixing-reactor (6).

3. The system for synthesizing core-shell structure copper-coated silver powder according to claim 1, wherein, A gas treatment device (10) is arranged at the gas phase outlet of the gas-liquid separator (9) for treating the gas generated in the synthesis of the nano-copper powder to meet the discharge standard.

4. The system for synthesizing core-shell structure copper-coated silver powder according to claim 1, wherein, A loop capable of being connected to the inlet end of the coating treatment tank (11) is arranged at the bottom of the coating treatment tank (11) for repeatedly coating the nano-copper core product.

5. The system for synthesizing core-shell structure copper-coated silver powder according to claim 1, wherein, A homogenization device for mixing the reaction materials is arranged in the coating treatment tank (11). A heating device for heating the internal reaction materials is arranged outside the coating treatment tank (11).

6. The system for synthesizing core-shell structure copper-coated silver powder according to claim 5, wherein, The homogenization device adopts a stirrer or an ultrasonic generator. The heating device adopts a heating jacket or a heating furnace.

7. A method of synthesizing core-shell structured silver-coated copper powder based on the system for synthesizing core-shell structured silver-coated copper powder according to any one of claims 1 to 6, characterized by, The method comprises the following steps: 1) Preparing a nano-copper core Pure water is conveyed to the cooler (7) through the pure water conveying unit and then into the mixing-reactor (6). Nano-copper raw materials are conveyed to the mixing-reactor (6) through the nano-copper conveying unit. The pure water and the nano-copper raw materials are reacted. The reaction product is sequentially subjected to cooling treatment by the cooler (7), pressure reduction treatment by the pressure reducer (8) and then passes through the gas-liquid separator (9) to obtain a nano-copper powder suspension which is sent into the coating treatment tank (11). 2) Preparing a silver-coated copper powder The sensitizing activator, the dispersing agent, the replacement agent and the reducing agent are respectively introduced into the coating treatment tank (11), the nano copper powder suspension is heated and reacted with the sensitizing activator, the dispersing agent, the replacement agent and the reducing agent for 20-60 minutes, the reaction material is separated through the solid-liquid separator (15), and the silver-coated copper powder with a core-shell structure is obtained; the replacement agent is one or both of silver nitrate solution and silver ammonia solution.

8. The method of claim 7, wherein the silver-coated copper powder has a core-shell structure. The reaction material is transported to the coating treatment tank (11) through the loop at the bottom of the coating treatment tank (11) to the inlet end for repeated coating treatment, so as to meet the thickness requirement of the silver coating layer.

9. The method of claim 7, wherein the silver-coated copper powder has a core-shell structure. The sensitizing activator is one or both of stannous chloride solution and palladium chloride solution; the dispersing agent is one or several of polyvinylpyrrolidone, polyethylene glycol and sodium dodecyl sulfate.

10. The method of synthesizing core-shell structured silver-coated copper powder according to claim 7, wherein, The reducing agent is one or several of formaldehyde, hydrazine hydrate, ascorbic acid, sodium hypophosphite and glucose.

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