An ultra-high density silver powder, a quasi-continuous preparation method and application thereof

Abstract

The application discloses a kind of ultra-high density silver powder and its quasi-continuous preparation method, the preparation method includes the following steps: reaction solution C is placed in the main reactor;Reaction solution A and reaction solution B are simultaneously added to the intermediate reactor containing water through the inlet of the intermediate reactor, and the material in the intermediate reactor is added to the main reactor through the outlet of the intermediate reactor, and the pH value in the main reactor is maintained between 2-10;The outlet of the main reactor is opened to discharge;The material is washed, separated, dried, crushed, and the ultra-high density silver powder is obtained.The method realizes quasi-continuous production of silver powder, and the production efficiency is high, and there is no phenomenon of pipe blockage.

Description

Technical Field

[0001] This invention relates to the field of silver powder preparation technology. More specifically, it relates to an ultra-high density silver powder, a quasi-continuous preparation method of the ultra-high density silver powder, and its applications. Background Technology

[0002] Solar-grade silver powder is a crucial raw material for solar cell fabrication, and its performance directly determines the quality of the solar cell. With the development of solar cell technology, higher technical requirements have been placed on the front-side silver paste. Higher silver content necessitates higher tap density and loose packing density in the solar-grade silver powder. Finer grids place even stricter requirements on the particle size distribution and dispersibility of the silver powder. As the solar cell market rapidly expands, the demand for raw materials is increasing year by year. Improving production efficiency and expanding production capacity are also urgent issues to be addressed in this field.

[0003] Current silver powder production mainly employs physical and chemical reduction methods, with the chemical reduction method primarily using intermittent production processes. This method suffers from poor batch-to-batch stability, leading to batch-to-batch variations in silver powder performance, and it cannot achieve continuous production, making it difficult to scale up production capacity. If quasi-continuous production of high-performance silver powder could be achieved, not only would the production efficiency be improved, but the stability of product quality could also be significantly enhanced. Summary of the Invention

[0004] Based on the above problems, the purpose of this invention is to provide an ultra-high density silver powder, a quasi-continuous preparation method of the ultra-high density silver powder, and its application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] On the one hand, the present invention provides a quasi-continuous preparation method for ultra-high density silver powder, the preparation method comprising the following steps:

[0007] 1) Prepare reaction solution A, which contains silver nitrate at a concentration of 15-250 g / L;

[0008] 2) Prepare reaction solution B, which contains a reducing agent with a concentration of 10-150 g / L, a dispersant with a concentration of 0-50 g / L, and a pH adjuster with a concentration of 0-150 g / L.

[0009] 3) Prepare reaction solution C, which contains a reducing agent with a concentration of 0-30 g / L, a dispersant with a concentration of 0-30 g / L, and a pH adjuster with a concentration of 0-15 g / L;

[0010] 4) Provide an intermediate reactor with an inlet and an outlet, and a main reactor with an inlet and an outlet, wherein the outlet of the intermediate reactor is connected to the inlet of the main reactor.

[0011] 5) Place reaction solution C in the main reactor; simultaneously add reaction solution A and reaction solution B into the intermediate reactor containing water through the inlet of the intermediate reactor, mix well, and at the same time add the material in the intermediate reactor into the main reactor through the outlet of the intermediate reactor. The feed rate and discharge rate of the intermediate reactor inlet are kept the same, and the pH value in the main reactor is maintained between 2 and 10.

[0012] 6) After the material in the intermediate reactor is continuously fed into the main reactor for a period of time, open the discharge port of the main reactor to discharge the material, and keep the discharge rate of the discharge port consistent with the feed rate of the intermediate reactor into the main reactor.

[0013] 7) The material coming out of the main reactor outlet will be washed, separated, and dried;

[0014] 8) Crush the dried material from step 7) to obtain the ultra-high density silver powder.

[0015] In the technical solution of the present invention, the feeding rate of the material entering the intermediate reactor and the discharge rate of the material exiting the outlet of the intermediate reactor are the same, that is, the liquid level in the intermediate reactor is maintained at a fixed height.

[0016] Currently, silver powder is produced intermittently. One approach to continuous production is through pipeline reactions, which has been implemented in the production of many materials. However, silver cannot be produced in pipelines because silver ions are reduced very quickly, resulting in a sudden large amount of solid precipitate in the flowing liquid. Furthermore, silver itself tends to aggregate, easily causing pipeline blockage. This application employs multiple sets of solutions for continuous feeding to achieve a continuous reaction. By introducing an intermediate reactor, the closed pipeline reaction is transformed into an open quasi-pipeline. The solutions mix in the intermediate reactor, and the reaction produces precipitation. Since it is no longer a closed pipeline, and the intermediate reactor is much larger than a pipeline reactor, the blockage of the pipeline by silver powder is completely avoided. (The inner diameter of a typical pipeline reactor is on the order of a few millimeters to a few centimeters, while the diameter of the intermediate reactor in this invention can reach tens of centimeters.)

[0017] More specifically, by controlling the feed rate to be consistent with the discharge rate of the intermediate reactor, and by adjusting the ratio of the reaction liquid remaining in the intermediate reactor to the feed rate, it is possible to control the residence time of the liquid in the intermediate reactor and the concentration of the material in the intermediate reactor. This provides a stable chemical environment for the growth of silver powder and ensures stable product performance. Furthermore, by using the intermediate reactor and the main reactor in combination, quasi-continuous production of ultra-high density silver powder can be achieved.

[0018] Furthermore, the reaction solution B contains a reducing agent at a concentration of 10-120 g / L, a dispersant at a concentration of 0.1-20 g / L, and a pH adjuster at a concentration of 1-130 g / L.

[0019] Furthermore, the reaction solution C contains a reducing agent at a concentration of 0-15 g / L, a dispersant at a concentration of 0-20 g / L, and a pH adjuster at a concentration of 0-10 g / L.

[0020] Furthermore, in reaction solutions A, B, and C, the solvent is water.

[0021] In this application, there are no other requirements for the selection of the reducing agent; any commonly used reducing agent that can be used in the preparation of silver powder is acceptable. Further, in steps 2) and 3), the reducing agent is selected from ascorbic acid.

[0022] Furthermore, in steps 2) and 3), the dispersant is independently selected from one or more of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and sodium polynaphthalene sulfonate.

[0023] Further, in steps 2) and 3), the pH adjuster is selected from NaOH and / or NH4HCO3. Further, in step 1), the temperature of reaction solution A is room temperature - 60°C.

[0024] Furthermore, in step 2), the temperature of reaction solution B is room temperature - 60°C.

[0025] Furthermore, in step 3), the temperature of the reaction solution C is room temperature - 60°C.

[0026] Furthermore, the volume ratio of reaction solution A, reaction solution B and reaction solution C is 1:1:(0.3-0.5).

[0027] Further, in step 8), the method for crushing the dried material in step 7) is as follows: adding a grinding aid to the dried material and crushing the material by an air jet mill.

[0028] Furthermore, the grinding aid is selected from one or more of oleic acid, stearic acid, decanoic acid, dodecylamine, and hexadecylamine.

[0029] Furthermore, in step 8), 0-3g of grinding aid is added to each kilogram of dried material.

[0030] Furthermore, in step 8), the pulverization method includes, but is not limited to, pulverization using an air jet mill or a rotary vane mill.

[0031] Further, in step 6), after the material in the intermediate reactor is continuously fed into the main reactor for 10 minutes, the outlet of the main reactor is opened to discharge the material.

[0032] Further, in step 5), the method for maintaining the pH value in the main reactor between 2 and 10 is to add a pH adjuster with a concentration of 0-150 g / L to the main reactor.

[0033] Furthermore, the pH adjuster is selected from NaOH and / or NH4HCO3.

[0034] Furthermore, reaction solution A and reaction solution B can be prepared separately in several batching tanks; each batching tank is independently connected to an intermediate reaction tank; reaction solution A and reaction solution B are added to the intermediate reaction tank simultaneously and sequentially through each batching tank, that is, after reaction solution A and reaction solution B from one batching tank have been added to the intermediate reaction tank, the material from the next batching tank continues to be added to the intermediate reaction tank. Through this step, continuous production of silver powder is achieved, improving production efficiency.

[0035] On another front, the present invention provides ultra-high density silver powder prepared by the preparation method described above, wherein the silver powder is a near-spherical ultrafine silver powder with a particle size between 0.5-5.0 μm, and the tap density of the silver powder can reach up to 7.1 g / cm³. 3 The bulk density can reach up to 5.4 g / cm³. 3 .

[0036] On the one hand, the present invention provides the application of ultra-high density silver powder prepared by the preparation method described above in the manufacture of solar cells.

[0037] Furthermore, the ultra-high density silver powder is used in the silver paste on the front side of the solar cell, and then used in the manufacture of the solar cell.

[0038] It should also be noted that, unless otherwise specified, any range described in this invention includes the endpoints, any values ​​between the endpoints, and any subranges formed by the endpoints or any values ​​between the endpoints. Unless otherwise specified, the preparation methods in this invention are conventional methods, and the raw materials used are all obtainable from publicly available commercial sources or prepared according to existing technology. Unless otherwise specified, the solutions are all aqueous solutions, and the reagents are all analytical grade.

[0039] The beneficial effects of this invention are as follows:

[0040] The preparation process of ultra-high density silver powder provided by this invention can realize the quasi-continuous production of silver powder, which improves production efficiency. At the same time, the introduction of intermediate reaction vessel improves the stability of the chemical environment for silver powder growth, making the product performance more stable, and there is no phenomenon of product clogging the pipeline.

[0041] The ultra-high density silver powder prepared by the method of this invention has extremely high bulk density and tap density, which can meet the increasingly higher silver filling requirements of solar cell silver paste. Simultaneously, the silver powder has a uniform particle size distribution, good flowability, and good compatibility with the paste after surface treatment. The paste prepared using this silver powder material meets the requirements for manufacturing solar cell front electrodes. Attached Figure Description

[0042] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0043] Figure 1 A scanning electron microscope image of the ultra-high density silver powder prepared in Example 2 is shown.

[0044] Figure 2 The particle size distribution diagram of the ultra-high density silver powder prepared in Example 2 is shown.

[0045] Figure 3 A scanning electron microscope image of the ultra-high density silver powder prepared in Example 8 is shown.

[0046] Figure 4 The particle size distribution of the ultra-high density silver powder prepared in Example 8 is shown.

[0047] Figure 5 A scanning electron microscope image of the ultra-high density silver powder prepared in Example 9 is shown.

[0048] Figure 6 The particle size distribution diagram of the ultra-high density silver powder prepared in Example 9 is shown. Detailed Implementation

[0049] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0050] Unless otherwise specified, all raw materials used in this invention can be obtained from publicly available commercial sources or prepared according to existing technology.

[0051] Example 1

[0052] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0053] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 20.0g / L, and control the temperature of reaction solution A at 30℃±5℃;

[0054] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 11.6g / L, the concentration of PEG (dispersant) is 0.15g / L, the concentration of sodium polynaphthalene sulfonate (dispersant) is 0.03g / L, and the concentration of NaOH (pH adjuster) is 1.17g / L. Control the temperature of reaction solution B at 30℃±5℃.

[0055] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 30℃±5℃;

[0056] 4) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 30L of purified water at a rate of 20L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 40L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0057] Both reaction solutions A and B can be dispensed multiple times via an additional mixing tank, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is used up.

[0058] 5) Add 1.0g of stearic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 4), and then pulverize it for 3 minutes using an air jet mill to obtain the ultra-high density silver powder.

[0059] No pipe blockage occurred during the preparation process.

[0060] The ultra-high density silver powder has an average particle size of 1.47 μm and a tap density of 5.99 g / cm³. 3 The loose bulk density is 3.33 g / cm³. 3 .

[0061] Example 2

[0062] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0063] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 20.0g / L, and control the temperature of reaction solution A at 30℃±5℃;

[0064] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 11.6g / L, the concentration of PEG (dispersant) is 0.15g / L, the concentration of sodium polynaphthalene sulfonate (dispersant) is 0.03g / L, the concentration of NaOH (pH adjuster) is 1.17g / L, and the temperature is controlled at 30℃±5℃;

[0065] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 30℃±5℃;

[0066] 4) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 30L of purified water at a rate of 20L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 40L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0067] Both reaction solutions A and B can be dispensed multiple times using an additional mixing tank, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is exhausted;

[0068] 5) Add 1.0g of stearic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 4), and then pulverize it for 5 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0069] No pipe blockage occurred during the preparation process.

[0070] The scanning electron microscope image of the ultra-high density silver powder is as follows: Figure 1 As shown, the particle size distribution is as follows Figure 2 As shown, the ultra-high density silver powder has an average particle size of 1.37 μm and a tap density of 6.22 g / cm³. 3 The loose bulk density is 3.86 g / cm³. 3 .

[0071] Example 3

[0072] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0073] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 20.0g / L, and control the temperature of reaction solution A at 30℃±5℃;

[0074] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 11.6g / L, the concentration of PEG (dispersant) is 0.15g / L, the concentration of sodium polynaphthalene sulfonate (dispersant) is 0.03g / L, and the concentration of NaOH (pH adjuster) is 1.17g / L. Control the temperature of reaction solution B at 30℃±5℃.

[0075] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 30℃±5℃;

[0076] 4) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 30L of purified water at a rate of 20L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 40L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0077] Both reaction solutions A and B can be dispensed multiple times using an additional mixing tank, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is exhausted;

[0078] 5) Add 0.65g of decanoic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 4), and then pulverize it for 5 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0079] No pipe blockage occurred during the preparation process.

[0080] The ultra-high density silver powder has an average particle size of 1.87 μm and a tap density of 6.08 g / cm³. 3 The loose bulk density is 3.35 g / cm³. 3 .

[0081] Example 4

[0082] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0083] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 20.0g / L, and control the temperature of reaction solution A at 30℃±5℃;

[0084] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 11.6g / L, the concentration of PEG (dispersant) is 0.15g / L, the concentration of sodium polynaphthalene sulfonate (dispersant) is 0.03g / L, and the concentration of NaOH (pH adjuster) is 1.17g / L. Control the temperature of reaction solution B at 30℃±5℃.

[0085] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 30℃±5℃;

[0086] 4) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 30L of purified water at a rate of 20L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 40L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0087] Both reaction solutions A and B can be dispensed multiple times using an additional mixing tank, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is exhausted;

[0088] 5) Add 0.67g of dodecylamine (grinding aid) to each kilogram of the dried material (silver powder) from step 4), and then pulverize it for 5 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0089] No pipe blockage occurred during the preparation process.

[0090] The ultra-high density silver powder has an average particle size of 3.07 μm and a tap density of 6.20 g / cm³. 3 The loose bulk density is 3.45 g / cm³. 3 .

[0091] Example 5

[0092] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0093] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 20.0g / L, and control the temperature of reaction solution A at 30℃±5℃;

[0094] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 11.6g / L, the concentration of PEG (dispersant) is 0.15g / L, the concentration of sodium polynaphthalene sulfonate (dispersant) is 0.03g / L, and the concentration of NaOH (pH adjuster) is 1.17g / L. Control the temperature of reaction solution B at 30℃±5℃.

[0095] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 30℃±5℃;

[0096] 4) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 30L of purified water at a rate of 20L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 40L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0097] Both reaction solutions A and B can be dispensed multiple times using an additional mixing tank, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is exhausted;

[0098] 5) Add 0.83g of hexadecylamine (grinding aid) to each kilogram of the dried material (silver powder) from step 4), and then pulverize it for 5 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0099] No pipe blockage occurred during the preparation process.

[0100] The ultra-high density silver powder has an average particle size of 1.59 μm and a tap density of 6.08 g / cm³. 3 The loose bulk density is 3.45 g / cm³. 3 .

[0101] Example 6

[0102] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0103] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 20.0g / L, and control the temperature of reaction solution A at 30℃±5℃;

[0104] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 11.6g / L, the concentration of PEG (dispersant) is 0.15g / L, the concentration of sodium polynaphthalene sulfonate (dispersant) is 0.03g / L, the concentration of NaOH (pH adjuster) is 1.17g / L, and the temperature is controlled at 30℃±5℃;

[0105] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 30℃±5℃;

[0106] 4) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 30L of purified water at a rate of 20L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 40L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0107] Both reaction solutions A and B can be dispensed multiple times through an additional batching vessel, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is exhausted;

[0108] 5) Add 0.6g of stearic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 4), and then pulverize it for 5 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0109] No pipe blockage occurred during the preparation process.

[0110] The ultra-high density silver powder has an average particle size of 3.27 μm and a tap density of 6.03 g / cm³. 3 The loose bulk density is 3.79 g / cm³. 3 .

[0111] Example 7

[0112] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0113] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 20.0g / L, and control the temperature of reaction solution A at 30℃±5℃;

[0114] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 11.6g / L, the concentration of PEG (dispersant) is 0.15g / L, the concentration of sodium polynaphthalene sulfonate (dispersant) is 0.03g / L, and the concentration of NaOH (pH adjuster) is 1.17g / L. Control the temperature of reaction solution B at 30℃±5℃.

[0115] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 30℃±5℃;

[0116] 4) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 30L of purified water at a rate of 20L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 40L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0117] Both reaction solutions A and B can be dispensed multiple times using an additional mixing tank, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is exhausted;

[0118] 6) Add 1.5g of stearic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 4), and then pulverize it for 3 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0119] No pipe blockage occurred during the preparation process.

[0120] The ultra-high density silver powder has an average particle size of 1.39 μm and a tap density of 5.89 g / cm³. 3 The loose bulk density is 3.42 g / cm³. 3 .

[0121] Example 8

[0122] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0123] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 200g / L, and control the temperature of reaction solution A at 50℃±5℃;

[0124] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 115g / L, the concentration of PVP (dispersant) is 20.0g / L, the concentration of NaOH (pH adjuster) is 23.3g / L, and control the temperature of reaction solution B at 50℃±5℃;

[0125] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 50℃±5℃;

[0126] 4) Prepare 200L of pH adjustment solution, ensuring that the concentration of NaOH (pH adjustment agent) in the solution is 70g / L, and control the temperature at 50℃±5℃;

[0127] 5) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 40L of purified water at a rate of 30L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 60L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. Simultaneously, add pH adjusting agent solution to the main reactor at a rate of 10L / min. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0128] Reaction solutions A and B, as well as pH adjusting agent solutions, can all be dispensed multiple times via an additional mixing tank, and quasi-continuous production can be achieved by switching the feeding pipeline when a set of materials is exhausted.

[0129] 6) Add 1.0g of stearic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 5), and then pulverize it for 4 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0130] No pipe blockage occurred during the preparation process.

[0131] The scanning electron microscope image of the ultra-high density silver powder is as follows: Figure 3 As shown, the particle size distribution is as follows Figure 4 As shown, the average particle size of this ultra-high density silver powder is 3.17 μm, and its tap density is 7.11 g / cm³. 3 The loose bulk density is 5.20 g / cm³. 3 .

[0132] Example 9

[0133] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0134] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 200g / L, and control the temperature of reaction solution A at 50℃±5℃;

[0135] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 115g / L, the concentration of PVP (dispersant) is 20.0g / L, the concentration of NaOH (pH adjuster) is 1.33g / L, and control the temperature of reaction solution B at 50℃±5℃;

[0136] 3) Use 200L of pure water as reaction solution C, and control the temperature of reaction solution C from room temperature to 50℃±5℃;

[0137] 4) Prepare 200L of pH adjustment solution, ensuring that the concentration of NaOH (pH adjustment agent) in the solution is 136g / L, and control the temperature at 50℃±5℃;

[0138] 5) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 40L of purified water at a rate of 30L / min. At the same time, open the discharge valve of the intermediate reactor. By controlling the outflow rate of the reaction liquid from the intermediate reactor to 60L / min, maintain the reaction liquid in the intermediate reactor at a fixed height. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. Simultaneously, add pH adjusting agent solution to the main reactor at a rate of 10L / min. After the valve of the intermediate reactor has been open for 10 minutes, the main reactor can begin to discharge. The reaction products are washed, separated, and then dried.

[0139] Reaction solutions A and B, as well as the pH adjuster solution, can all be dispensed multiple times via an additional mixing tank. When a set of materials is exhausted, the feeding pipeline is switched to achieve quasi-continuous production.

[0140] 6) Add 1.0g of stearic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 5), and then pulverize it for 5 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0141] No pipe blockage occurred during the preparation process.

[0142] The scanning electron microscope image of the ultra-high density silver powder is as follows: Figure 5 As shown, the particle size distribution is as follows Figure 6 As shown, the ultra-high density silver powder has an average particle size of 1.53 μm and a tap density of 7.08 g / cm³. 3 The loose bulk density is 5.41 g / cm³. 3 .

[0143] Example 10

[0144] A quasi-continuous preparation method for ultra-high density silver powder includes the following steps:

[0145] 1) Prepare 600L of reaction solution A, ensuring that the concentration of silver nitrate in reaction solution A is 200g / L, and control the temperature of reaction solution A to room temperature;

[0146] 2) Prepare 600L of reaction solution B, ensuring that the concentration of ascorbic acid (reducing agent) in reaction solution B is 115g / L, the concentration of PVP (dispersant) is 20.0g / L, the concentration of NH4HCO3 (pH adjuster) is 130g / L, and control the temperature of reaction solution B to room temperature;

[0147] 3) Prepare 200L of reaction solution C, ensuring that the concentration of ascorbic acid (reducing agent) in the solution is 15g / L, the concentration of PVP (dispersant) is 20.0g / L, the concentration of NH4HCO3 (pH adjuster) is 10.0g / L, and the temperature is controlled at room temperature;

[0148] 4) Prepare 200L of pH adjustment solution, ensuring that the concentration of NaOH (pH adjustment agent) in the solution is 136g / L, and control the temperature at 50℃±5℃;

[0149] 5) Place reaction solution C in the main reactor. Simultaneously add reaction solutions A and B to an intermediate reactor containing 40L of purified water at a rate of 30L / min. At the same time, open the discharge valve of the intermediate reactor. Maintain the reaction solution in the intermediate reactor at a constant height by controlling the outflow rate of the reaction solution to 60L / min. After mixing in the intermediate reactor, reaction solutions A and B flow into the main reactor containing reaction solution C. Simultaneously, add pH adjusting agent solution to the main reactor at a rate of 10L / min. After the intermediate reactor valve has been open for 10 minutes, the main reactor can begin discharging. The reaction products are washed, separated, and dried.

[0150] Reaction solutions A and B, as well as the pH adjuster solution, can all be dispensed multiple times via an additional mixing tank. When a set of materials is exhausted, the feeding pipeline is switched to achieve quasi-continuous production.

[0151] 6) Add 1.0g of stearic acid (grinding aid) to each kilogram of the dried material (silver powder) from step 5), and then pulverize it for 5 minutes using a rotary vane pulverizer to obtain the ultra-high density silver powder.

[0152] No pipe blockage occurred during the preparation process.

[0153] The tap density of this ultra-high density silver powder is 5.54 g / cm³. 3 The loose bulk density is 2.94 g / cm³. 3 .

[0154] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A quasi-continuous preparation method for ultra-high density silver powder, characterized in that, Includes the following steps: 1) Prepare reaction solution A, which contains silver nitrate at a concentration of 15-250 g / L; 2) Prepare reaction solution B, which contains a reducing agent with a concentration of 10-150 g / L, a dispersant with a concentration of 0-50 g / L, and a pH adjuster with a concentration of 0-150 g / L. 3) Prepare reaction solution C, which contains a reducing agent with a concentration of 0-30 g / L, a dispersant with a concentration of 0-30 g / L, and a pH adjuster with a concentration of 0-15 g / L; 4) Provide an intermediate reactor with an inlet and an outlet, and a main reactor with an inlet and an outlet, wherein the outlet of the intermediate reactor is connected to the inlet of the main reactor. 5) Place reaction solution C in the main reactor; through the inlet of the intermediate reactor, simultaneously add reaction solution A and reaction solution B to the intermediate reactor containing water, mix well, and at the same time, add the material in the intermediate reactor to the main reactor through the outlet of the intermediate reactor. The feed rate and discharge rate of the intermediate reactor inlet are kept the same, and the pH value in the main reactor is maintained between 2 and 10. 6) After the material in the intermediate reactor is continuously fed into the main reactor for a period of time, open the discharge port of the main reactor to discharge the material, and keep the discharge rate of the discharge port consistent with the feed rate of the intermediate reactor into the main reactor. 7) The material coming out of the main reactor outlet will be washed, separated, and dried; 8) Crush the dried material from step 7) to obtain the ultra-high density silver powder.

2. The preparation method according to claim 1, characterized in that, The reaction solution B contains a reducing agent at a concentration of 10-120 g / L, a dispersant at a concentration of 0.1-20 g / L, and a pH adjuster at a concentration of 1-130 g / L.

3. The preparation method according to claim 1 or 2, characterized in that, The reducing agent is selected from ascorbic acid; The dispersant is selected from one or more of polyvinylpyrrolidone, polyethylene glycol, and sodium polynaphthalene sulfonate; The pH adjuster is selected from NaOH and / or NH4HCO3.

4. The preparation method according to claim 1, characterized in that, The volume ratio of reaction solution A, reaction solution B and reaction solution C is 1:1:(0.3-0.5).

5. The preparation method according to claim 1, characterized in that, In step 8), the method for crushing the dried material in step 7) is as follows: add a grinding aid to the dried material and crush the material by air jet mill.

6. The preparation method according to claim 5, characterized in that, The grinding aid is selected from one or more of oleic acid, stearic acid, decanoic acid, dodecylamine, and hexadecylamine; Preferably, in step 8), 0-3g of grinding aid is added to each kilogram of dried material.

7. The preparation method according to claim 1, characterized in that, In step 5), the method to maintain the pH value in the main reactor between 2 and 10 is to add a pH adjuster with a concentration of 0-150 g / L to the main reactor.

8. The preparation method according to claim 1, characterized in that, The reaction solution A and reaction solution B can be prepared in several mixing tanks respectively; reaction solution A and reaction solution B are added simultaneously to the intermediate reaction tank containing water through each mixing tank.

9. The ultra-high density silver powder prepared by the preparation method according to any one of claims 1-8, characterized in that, The silver powder is a near-spherical ultrafine silver powder with a particle size between 0.5 and 5.0 μm, and the tap density of the silver powder can reach up to 7.1 g / cm³. 3 The bulk density can reach up to 5.4 g / cm³. 3 .

10. The application of the ultra-high density silver powder prepared by the preparation method according to any one of claims 1-8 in the manufacture of solar cells.

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