A high specific surface area and high activity single-particle dispersed silver powder and its preparation method

Abstract

The present invention discloses a high-specific surface area, high-activity, single-particle dispersed silver powder and a preparation method thereof. The prepared silver powder exhibits high specific surface area, high activity, and a single-particle distribution. Silver pastes made with this silver powder are suitable for use in specialized high-temperature sintering processes, with peak temperatures exceeding 700°C, offering unique advantages. The silver powder prepared by this invention is suitable for use in the production of high-temperature silver pastes required for the silver powder industry, such as high-temperature glass etching silver paste, special piezoelectric ceramic silver paste, and photovoltaic silver paste.

Description

Technical Field

[0001] The invention belongs to the technical field of silver powder in high-temperature silver paste, and particularly relates to a high-specific surface area and high-activity single-particle dispersed silver powder and a preparation method thereof. Background Art

[0002] With the development of the silver powder industry, more and more companies are participating in the technical research and development and production of silver powder. Various types and characteristics of silver powder have been developed, recognized by the market and completed large-scale production and application.

[0003] At present, the existing high-activity silver powder generally has the characteristics of relatively high specific surface area, high sintering activity, low tap density, relatively small silver powder particle size, and relatively wide distribution of silver powder particles. For example, Ag07 silver powder is a representative of this type. However, this type of silver powder is not suitable for high-temperature silver paste, especially in high-temperature sintering processes. High-temperature silver paste prepared with this type of silver powder is prone to blistering of the silver layer.

[0004] At present, the existing sintering-resistant silver powder generally has the characteristics of relatively small specific surface area, low sintering activity, slightly high tap density, and suitable silver powder particle size distribution, such as Ag02 silver powder and photovoltaic positive silver powder. However, although this type of silver powder is suitable for high-temperature sintering process, due to its low activity, the high-temperature silver paste using this type of silver powder generally requires a longer sintering time and a higher sintering temperature. If the sintering temperature is not enough or the sintering time is too short, the silver layer and the substrate are likely to be loosely bonded, resulting in the phenomenon of silver layer falling off, and the sintered silver layer is prone to matte and yellowing of the silver layer surface; and in certain production process conditions that require laser fine etching, due to problems such as too wide distribution of silver powder particles or poor dispersion of single silver powder particles, the silver layer circuits made using high-temperature silver paste of this type of silver powder are prone to poor etching or etched circuit burrs, ultimately resulting in a relatively low product yield. Summary of the Invention

[0005] To address the existing problems with the application of high-activity silver powder and sintering-resistant silver powder in high-temperature silver pastes, the present invention provides a high-specific surface area, high-activity, single-particle dispersed silver powder and a method for preparing the same. The prepared silver powder has high specific surface area and high activity, and exhibits a single-particle distribution. The silver paste prepared using this silver powder is suitable for special high-temperature sintering processes, with peak temperatures exceeding 700°C, offering unique advantages. The silver powder prepared by the present invention is suitable for the production of high-temperature silver pastes required in the silver powder industry, such as high-temperature glass etching silver paste, special piezoelectric ceramic silver paste, and photovoltaic silver paste.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing high-specific surface area and high-activity single-particle dispersed silver powder comprises the following steps:

[0008] S1. Mix silver nitrate and deionized water in a mass ratio of 1:(5-7), stir and dissolve in reactor A, and then stir for 5 minutes. Then, add 80%-99.7% volume concentration of triethanolamine solution, the amount of triethanolamine solution added is 0.08%-0.2% of the mass of silver nitrate, continue stirring, and control the temperature at 47°C-50°C;

[0009] S2, in reactor B, add deionized water, vitamin C, dispersant I and dispersant II, wherein the mass ratio of the added mass of vitamin C and silver nitrate is 1:(1.2-1.5), the added amount of dispersant I is 12%-15% of the mass of silver nitrate, the added amount of dispersant II is 1%-3% of the mass of silver nitrate, the mass ratio of vitamin C and deionized water is 1:(5-18), after stirring and dissolving in reactor B, stir for 5min, then add 80%-99.7% volume concentration of triethanolamine solution, the added amount of triethanolamine solution is 10%-25% of the mass of silver nitrate, continue stirring, and temperature is controlled at 47 ℃-50 ℃;

[0010] The dispersant I is selected from polyvinylpyrrolidone (PVP); the dispersant II is selected from modified polyethers;

[0011] S3, the solution in reactor A is added to reactor B at a uniform rate, and stirred continuously, the addition process is controlled within 5min-15min, and after all are added, stirring is continued for 10min-15min to fully react, and then the silver powder and the solution are separated to obtain wet silver powder, and the wet silver powder is washed with deionized water. When the conductivity of the wet silver powder is ≤30, alcohol with a volume concentration of 99% or more is added to remove water and wash until the conductivity of the alcohol-mixed wet silver powder is ≤20;

[0012] S4, dissolving the coating agent in alcohol with a volume concentration of 95% or more, the amount of the coating agent added is 0.1%-0.2% of the mass of the silver nitrate, and the amount of alcohol added with a volume concentration of 95% or more is 3 times to 5 times the mass of the coating agent, and then adding the mixture to the alcohol-mixed wet silver powder obtained in the previous step, stirring, and separating;

[0013] The coating agent is selected from stearic acid, oleic acid, or a mixture of the two in any proportion;

[0014] S5, drying the wet silver powder separated in the above step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder, the particle size distribution of the silver powder is D 10 It is 0.81-0.85, D 50 It is 1.82-2.20, D90 It is 2.70-2.91, the specific surface area is 0.43-0.48, and the tap density is 5.9-6.1.

[0015] In the present invention:

[0016] The triethanolamine described in steps S1 and S2 acts as a surfactant during the silver powder synthesis process, attaching to the surface of the silver powder particles and providing them with lipophilic and hydrophilic functional groups. This allows the resulting silver powder to be effectively suspended in the solution, achieving a good dispersion effect. Furthermore, in the present invention, triethanolamine, a weakly alkaline solution, is used instead of existing strong alkaline solutions or aqueous ammonia solutions. After the solutions in Reactors A and B are mixed and reacted, the pH value during the silver powder synthesis process remains minimal, thereby ensuring that the silver powder particle size is concentrated and dispersed as single particles. The temperature is controlled within the range specified in the present invention to control the crystal growth during the silver powder reaction and maintain the desired activity. As can be seen from the SEM images, the silver powder synthesized by this method has a relatively large number of cracks and other dislocation defects on its surface. This structure of silver powder is relatively active and can be quickly fused and formed under high-temperature rapid sintering, resulting in a low bulk resistance silver layer.

[0017] The dispersant I described in step S2 is preferably PVP-K30S or PVP-K30. The function of this type of PVP dispersant is to increase the viscosity of the solution during the silver powder reaction process. In addition, during the chemical reaction of the silver powder, the PVP resin adheres to the surface of the silver powder particles, so that the synthesized silver powder is in a single particle dispersion state.

[0018] The dispersant II described in step S2 is selected from a modified polyether, preferably a hydroxy acrylic acid modified polyether. The function of such a modified polyether dispersant is to concentrate the particle size of the generated silver powder, so that the silver powder particles are separated from each other in the solution without forming hard agglomerates. At the same time, the use of a high molecular weight modified polyether dispersant can also increase the viscosity of the aqueous solution, improve the suspension performance of the silver powder particles, and enhance the dispersion performance of the silver powder particles. The molecular weight is controlled to be 20,000-50,000 so that the silver powder particles produced by the reaction are within the target range and achieve the expected experimental results.

[0019] The present invention also relates to a high specific surface area and high activity single particle dispersed silver powder, which is obtained by using the above-mentioned preparation method of a high specific surface area and high activity single particle dispersed silver powder, and the silver powder has a particle size distribution of D 10 It is 0.81-0.85, D 50 It is 1.82-2.20, D 90 It is 2.70-2.91, the specific surface area is 0.43-0.48, and the tap density is 5.9-6.1.

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

[0021] 1. The method for preparing a high-specific surface area and high-activity single-particle dispersed silver powder described in the present invention has large silver powder particles, which are less likely to cause blistering during sintering. In addition, the silver powder has relatively high activity, and the sintering of the silver layer circuit can be completed at a lower sintering temperature and a shorter sintering time, so that the silver layer and the substrate are tightly bonded. In addition, the sintered silver layer exhibits a bright white color. In certain production process conditions requiring laser fine etching, the concentrated distribution of the silver powder particles and the single-particle dispersion of the silver powder particles result in a very high circuit yield after etching, making it suitable for such special requirements.

[0022] 2. The high specific surface area and high activity single-particle dispersed silver powder described in the present invention can meet the current needs of photovoltaic silver powder. After the prepared silver powder is formulated into solar front silver paste, it can meet the requirements of the production line and can meet the current performance requirements of the photovoltaic industry for domestic silver powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0024] Figure 1 This is a scanning electron microscope image (10,000 times magnified) of the high specific surface area and high activity single-particle dispersed silver powder prepared in Example 1 of the present invention;

[0025] Figure 2 This is a scanning electron microscope image (2,000 times magnification) of the high-specific surface area and high-activity single-particle dispersed silver powder prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1:

[0028] A method for preparing high-specific surface area and high-activity single-particle dispersed silver powder comprises the following steps:

[0029] S1. In reactor A, 12 kg of silver nitrate and 70 liters of deionized water were mixed and stirred to dissolve, and then stirred for 5 minutes. Then, 10 g of 99% triethanolamine solution was added and stirring was continued. The temperature was controlled at 47-50°C.

[0030] S2. In reactor B, 10 kg of vitamin C was added to 60 L of deionized water, along with 1.5 kg of dispersant PVP-30S and 120 g of 3W molecular weight hydroxylated acrylic acid modified polyether (Zhejiang Weifa New Material Technology Co., Ltd.). The mixture was stirred and dissolved in the reactor, followed by stirring for 5 min. Then, 1.5 kg of 99% triethanolamine solution was added, and stirring was continued. The temperature was controlled at 47-50°C.

[0031] S3, the solution in reactor A is added to reactor B at a uniform rate, and stirred continuously. The addition process is controlled within 10 minutes. After all the solution is added, stirring is continued for 10 minutes for sufficient reaction. Then, the silver powder and the solution are separated, and the conductivity of the wet silver powder reaches 30 after washing with deionized water. Then, 99% volume concentration of alcohol is added for dewatering and cleaning. The conductivity of the alcohol-mixed wet silver powder reaches 20.

[0032] S4, dissolving 12g of stearic acid as a coating agent in 60g of 99% volume concentration of alcohol, then adding it to the wet silver powder, stirring, and separating;

[0033] S5, drying the wet silver powder separated in the above step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder, the particle size distribution of the silver powder is D 10 It is 0.83, D 50 It is 1.9, D 90 It is 2.8, the specific surface area is 0.47, and the tap density is 6.1.

[0034] Example 2:

[0035] A method for preparing high-specific surface area and high-activity single-particle dispersed silver powder comprises the following steps:

[0036] S1. In reactor A, 12 kg of silver nitrate and 60 liters of deionized water were mixed and stirred to dissolve, and then stirred for 5 minutes. Then, 23 g of 99% triethanolamine solution was added and stirring was continued. The temperature was controlled at 47-50°C.

[0037] S2. In reactor B, 9 kg of vitamin C was added to 60 L of deionized water, along with 1.5 kg of dispersant PVP-K30 and 230 g of 3W molecular weight hydroxylated acrylic acid modified polyether (Zhejiang Weifa New Material Technology Co., Ltd.). The mixture was stirred and dissolved in the reactor, followed by stirring for 5 min. Then, 2 kg of 99% triethanolamine solution was added, and stirring was continued. The temperature was controlled at 47-50°C.

[0038] S3, the solution in reactor A is added to reactor B at a uniform rate, and stirred continuously. The addition process is controlled within 10 minutes. After all the solution is added, stirring is continued for 10 minutes for sufficient reaction. Then, the silver powder and the solution are separated, and the conductivity of the wet silver powder reaches 30 after washing with deionized water. Then, 99% volume concentration of alcohol is added for dewatering and cleaning. The conductivity of the alcohol-mixed wet silver powder reaches 20.

[0039] S4, dissolving 12g of coating agent oleic acid in 60g of 99% volume concentration alcohol, then adding it to the wet silver powder, stirring, and separating;

[0040] S5, drying the wet silver powder separated in the previous step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder;

[0041] The particle size distribution of the silver powder is D 10 It is 0.81, D 50 It is 1.82, D 90 It is 2.7, the specific surface area is 0.48, and the tap density is 6.1.

[0042] Example 3:

[0043] A method for preparing high-specific surface area and high-activity single-particle dispersed silver powder comprises the following steps:

[0044] S1. In reactor A, 12 kg of silver nitrate and 80 liters of deionized water were mixed and stirred to dissolve, and then stirred for 5 minutes. Then, 17 g of 99% triethanolamine solution was added and stirring was continued. The temperature was controlled at 47-50°C.

[0045] S2. In reactor B, 8 kg of vitamin C was added to 60 L of deionized water, along with 1.8 kg of dispersant PVP-30S and 330 g of 3W molecular weight hydroxylated acrylic acid modified polyether (Zhejiang Weifa New Material Technology Co., Ltd.). The mixture was stirred and dissolved in the reactor, followed by stirring for 5 min. Then, 2.8 kg of 99% triethanolamine solution was added, and stirring was continued. The temperature was controlled at 47-50°C.

[0046] S3, the solution in reactor A is added to reactor B at a uniform rate, and stirred continuously. The addition process is controlled within 10 minutes. After all the solution is added, stirring is continued for 10 minutes for sufficient reaction. Then, the silver powder and the solution are separated, and the conductivity of the wet silver powder reaches 30 after washing with deionized water. Then, 99% volume concentration of alcohol is added for dewatering and cleaning. The conductivity of the alcohol-mixed wet silver powder reaches 20.

[0047] S4, dissolving 6g of stearic acid and 6g of oleic acid in 60g of 99% alcohol by volume, then adding the mixture to the wet silver powder, stirring, and separating.

[0048] S5, drying the wet silver powder separated in the previous step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder;

[0049] The silver powder particle size distribution is D 10 It is 0.85, D 50 It is 2.2, D 90 It is 2.91, the specific surface area is 0.43, and the tap density is 5.9.

[0050] Comparative Example 1:

[0051] The difference between Comparative Example 1 and Example 1 is that ammonia water is used instead of triethanolamine, and the rest is the same as Example 1;

[0052] The preparation of silver powder comprises the following steps:

[0053] (1) In reactor A, 12 kg of silver nitrate and 70 liters of deionized water were mixed and stirred to dissolve, and then stirred for 5 minutes. Then, 3 g of 30% ammonia solution was added and stirred continuously. The temperature was controlled at 47-50 °C.

[0054] (2) In reactor B, 10 kg of vitamin C was added to 60 L of deionized water, and 1.6 kg of dispersant PVP-30S was added at the same time. 150 g of 3W molecular weight hydroxy acrylic acid modified polyether (Zhejiang Weifa New Material Technology Co., Ltd.) was added. After stirring and dissolving in the reactor, the mixture was stirred for 5 min. Then, 4.5 kg of 30% volume concentration ammonia solution was added. The stirring was continued and the temperature was controlled at 47-50 °C.

[0055] (3) Add the solution in reactor A to reactor B at a constant rate while stirring continuously. The addition process is controlled within 10 minutes. After all the solution is added, continue stirring for 10 minutes to allow for sufficient reaction. Then separate the silver powder and the solution, and wash the wet silver powder with deionized water until the conductivity reaches about 30. Then add 99% volume concentration of alcohol to remove water and wash. The conductivity of the alcohol-mixed wet silver powder reaches below 20.

[0056] (4) Dissolve 12g of stearic acid as a coating agent in 60g of alcohol, then add it to the wet silver powder, stir, and separate;

[0057] (5) drying the wet silver powder separated in the previous step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder;

[0058] The silver powder particle size distribution is D 10It is 0.5, D 50 It is 1.9, D 90 It is 3.6, the specific surface area is 0.34, and the tap density is 5.8.

[0059] Comparative Example 2:

[0060] The difference between Comparative Example 2 and Example 1 is that the dispersant such as polyvinylpyrrolidone (PVP) is removed, and the other processes are the same as those in Example 1;

[0061] The preparation of silver powder comprises the following steps:

[0062] (1) In reactor A, 12 kg of silver nitrate and 70 liters of deionized water were mixed and stirred to dissolve, and then stirred for 5 minutes. Then, 10 g of 99% triethanolamine solution was added and the stirring was continued. The temperature was controlled at 47-50°C.

[0063] (2) In reactor B, 10 kg of vitamin C was added to 60 L of deionized water, and 150 g of 3W molecular weight hydroxy acrylic acid modified polyether (Zhejiang Weifa New Material Technology Co., Ltd.) was added at the same time. After stirring and dissolving in the reactor, the mixture was stirred for 5 min, and then 1.5 kg of 99% triethanolamine solution was added. The mixture was stirred continuously and the temperature was controlled at 47-50 °C.

[0064] (3) Add the solution in reactor A to reactor B at a constant rate while stirring continuously. The addition process is controlled within 10 minutes. After all the solution is added, continue stirring for 10 minutes to allow for sufficient reaction. Then separate the silver powder and the solution, and wash the wet silver powder with deionized water until the conductivity reaches about 30. Then add 99% volume concentration of alcohol to remove water and wash. The conductivity of the alcohol-mixed wet silver powder reaches below 20.

[0065] (4) Dissolve 12g of stearic acid as a coating agent in 60g of alcohol, then add it to the wet silver powder, stir, and separate;

[0066] (5) drying the wet silver powder separated in the previous step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder;

[0067] The silver powder particle size distribution is D 10 It is 0.52, D 50 It is 2.4, D 90 It is 4.9, the specific surface area is 0.21, and the tap density is 5.3.

[0068] Comparative Example 3:

[0069] The difference between Comparative Example 3 and Example 1 is that the temperature range of the entire solution is different from the temperature control range of the entire solution in Example 1, and the rest is the same as Example 1;

[0070] The preparation of silver powder comprises the following steps:

[0071] (1) In reactor A, 12 kg of silver nitrate and 70 liters of deionized water were mixed and stirred to dissolve, and then stirred for 5 minutes. Then, 10 g of 99% triethanolamine solution was added and the stirring was continued. The temperature was controlled at 25-27 °C.

[0072] (2) In reactor B, 10 kg of vitamin C was added to 60 L of deionized water, and 1.6 kg of dispersant PVP-30S was added at the same time. 150 g of 3W molecular weight hydroxy acrylic acid modified polyether (Zhejiang Weifa New Material Technology Co., Ltd.) was added. After stirring and dissolving in the reactor, the mixture was stirred for 5 min, and then 1.5 kg of 99% triethanolamine solution was added. The mixture was stirred continuously and the temperature was controlled at 25-27 °C.

[0073] (3) Add the solution in reactor A to reactor B at a constant rate while stirring continuously. The addition process is controlled within 10 minutes. After all the solution is added, continue stirring for 10 minutes to allow for sufficient reaction. Then separate the silver powder and the solution, and wash the wet silver powder with deionized water until the conductivity reaches about 30. Then add 99% volume concentration of alcohol to remove water and wash. The conductivity of the alcohol-mixed wet silver powder reaches below 20.

[0074] (4) Dissolve 12g of stearic acid as a coating agent in 60g of alcohol, then add it to the wet silver powder, stir, and separate;

[0075] (5) drying the wet silver powder separated in the previous step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder;

[0076] The silver powder particle size distribution is D 10 It is 0.75, D 50 It is 1.7, D 90 is 2.6, the specific surface area is 0.24, and the tap density is 6.0.

[0077] Performance testing:

[0078] The silver powder obtained in Example 1 was prepared into high-temperature glass silver paste 1, the silver powder obtained in Comparative Example 1 was prepared into high-temperature glass silver paste 2, the silver powder obtained in Comparative Example 2 was prepared into high-temperature glass silver paste 3, and the silver powder obtained in Comparative Example 3 was prepared into high-temperature glass silver paste 4. These pastes were then used on a glass substrate for printing, sintering, and etching. The product performance was tested, and the specific indicators are shown in Table 1:

[0079] Table 1: Sintering process performance, silver paste etching performance, and final circuit yield test

[0080]

[0081] The silver powder obtained in Example 1 was prepared into high-temperature glass silver paste 1, the Zhongke copper Ag07 silver powder was prepared into high-temperature glass silver paste 5, and the Zhongke copper Ag02 silver powder was prepared into high-temperature glass silver paste 6. These pastes were then used on a glass substrate for printing, sintering, and etching. Finally, the product performance was tested. The specific indicators are shown in Table 2:

[0082] Table 2: Sintering process performance, silver paste etching performance, and final circuit yield test

[0083]

[0084] The silver powder obtained in Example 1 was formulated into solar front silver paste A, the silver powder obtained in Comparative Example 1 was formulated into solar front silver paste B, the silver powder obtained in Comparative Example 2 was formulated into solar front silver paste C, and the silver powder obtained in Comparative Example 3 was formulated into solar front silver paste D. These pastes were then printed and sintered, and their performance was tested. The specific indicators are shown in Table 3:

[0085] Table 3: Silver paste printing and rapid sintering performance test in solar production line

[0086]

[0087] The silver powder obtained in Example 1 was formulated into solar front silver paste A, and compared with the solar silver paste of the production line. The electrical properties are shown in Table 4:

[0088] Table 4: Electrical performance test of silver paste in solar production line

[0089]

[0090] Results and Discussion

[0091] It can be seen from Tables 1 to 4 that the comprehensive effects of the embodiments are very good, the silver powder particle size distribution meets the requirements, the specific surface area reaches 0.47, and the tap density reaches 6.1.

[0092] From the comparison between Example 1 and Comparative Example 1, it can be seen that Figure 1 This is a 10,000-fold magnified scanning electron microscope image of the high specific surface area and high activity single-particle dispersed silver powder of Example 1. Figure 2This is a 2,000x magnified scanning electron microscope image of the high-specific surface area, high-activity, single-particle dispersed silver powder in Example 1. If other alkaline substances such as ammonia water are used in place of triethanolamine in Reactors A and B, the dispersing effect of triethanolamine will adversely affect the dispersibility of the silver powder particles produced in the subsequent reaction, resulting in the final silver powder product failing to achieve ideal particle size distribution, specific surface area data, and tap compaction. Analysis of the data from Comparative Example 1 shows that the overall silver powder exhibits a small amount of large particle agglomeration. A comparison of Example 1 and Comparative Example 2 shows that if PVP-K30S is removed from the dispersant, the final silver powder product also exhibits significant particle agglomeration. The overall silver powder data from Comparative Example 2 shows relatively severe agglomeration, resulting in the final silver powder product failing to achieve ideal performance in all indicators.

[0093] A comparison of Example 1 and Comparative Example 3 shows that changing the reaction temperature reduces the specific surface area of ​​the silver powder, affecting its subsequent sintering activity. Comparative Example 3 shows that, while the particle size distribution and tap density of the silver powder do not change much as in Example 1, the specific surface area decreases significantly as the temperature decreases.

[0094] The silver powders obtained in Example 1 and Comparative Examples 1-3 were formulated into high-temperature glass silver pastes. The performance of the tests showed that the silver paste prepared from the silver powder in Example 1 met all process requirements, especially in terms of sintering activity, which enabled it to meet the high-temperature, rapid sintering characteristics of the glass base. Furthermore, the subsequent performance tests also met the production line requirements, such as a very high yield rate in circuit etching. However, the silver pastes prepared from the various silver powders in Comparative Examples 1-3 all had various problems, as these silver powders had relatively small specific surface area, poor activity, and poor dispersibility, resulting in a relatively high defect rate in subsequent circuit etching.

[0095] Example 1, existing domestic high-activity silver powder, and existing sintering-resistant silver powder were formulated into high-temperature glass silver pastes. Performance tests showed that Example 1 met all requirements, while existing domestic high-activity silver powder exhibited high-temperature sintering bubbles, ultimately leading to poor circuit performance and product failure. Furthermore, existing domestic sintering-resistant silver powders exhibited relatively poor sintering activity, resulting in inability to meet high-temperature, rapid sintering requirements and subsequent etching defects during circuit etching.

[0096] The silver powders obtained in Example 1 and Comparative Examples 1-3 were formulated into solar front silver pastes and tested for various properties. The silver paste prepared from the silver powder in Example 1 met the production line requirements and was essentially identical to the production line paste in the final electrical performance tests. However, the solar silver pastes prepared from the silver powders in Comparative Examples 1-3 exhibited high viscosity due to agglomeration issues, or were unable to achieve rapid sintering due to the silver powder's activity, failing to meet the production line's process requirements.

[0097] The above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications may be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a high specific surface area and high activity single-particle dispersed silver powder, characterized by: The following steps are involved: S1. Mix silver nitrate and deionized water in a mass ratio of 1:(5-7), stir and dissolve in reactor A, and then stir for 5 minutes. Then, add 80%-99.7% volume concentration of triethanolamine solution, the amount of triethanolamine solution added is 0.08%-0.2% of the mass of silver nitrate, continue stirring, and control the temperature at 47°C-50°C; S2, in reactor B, add deionized water, vitamin C, dispersant I and dispersant II, wherein the mass ratio of the added mass of vitamin C and silver nitrate is 1:(1.2-1.5), the added amount of dispersant I is 12%-15% of the mass of silver nitrate, the added amount of dispersant II is 1%-3% of the mass of silver nitrate, the mass ratio of vitamin C and deionized water is 1:(5-18), after stirring and dissolving in reactor B, stir for 5min, then add 80%-99.7% volume concentration of triethanolamine solution, the added amount of triethanolamine solution is 10%-25% of the mass of silver nitrate, continue stirring, and temperature is controlled at 47 ℃-50 ℃; The dispersant I is selected from polyvinyl pyrrolidone; the dispersant II is selected from modified polyethers; S3, the solution in reactor A is added to reactor B at a uniform rate, and stirred continuously, the addition process is controlled within 5min-15min, and after all are added, stirring is continued for 10min-15min to fully react, and then the silver powder and the solution are separated to obtain wet silver powder, and the wet silver powder is washed with deionized water. When the conductivity of the wet silver powder is ≤30, alcohol with a volume concentration of 99% or more is added to remove water and wash until the conductivity of the alcohol-mixed wet silver powder is ≤20; S4, dissolving the coating agent in alcohol with a volume concentration of 95% or more, the amount of the coating agent added is 0.1%-0.2% of the mass of the silver nitrate, and the amount of alcohol added with a volume concentration of 95% or more is 3 times to 5 times the mass of the coating agent, and then adding the mixture to the alcohol-mixed wet silver powder obtained in the previous step, stirring, and separating; The coating agent is selected from stearic acid, oleic acid, or a mixture of the two in any proportion; S5, drying the wet silver powder separated in the above step, and then performing air grinding to finally obtain a high specific surface area and high activity single particle dispersed silver powder, the particle size distribution of the silver powder is D 10 It is 0.81-0.85, D 50 It is 1.82-2.20, D 90 It is 2.70-2.91, the specific surface area is 0.43-0.48, and the tap density is 5.9-6.

1.

2. The method for preparing a high specific surface area and high activity single-particle dispersed silver powder according to claim 1, characterized in that: The dispersant I described in step S2 is selected from polyvinylpyrrolidone PVP-K30S or PVP-K30.

3. The method for preparing a high specific surface area and high activity single-particle dispersed silver powder according to claim 1, characterized in that: The dispersant II described in step S2 is selected from hydroxy acrylic acid modified polyether.

4. A high specific surface area and high activity single particle dispersed silver powder, characterized by: The method for preparing a high specific surface area and high activity single particle dispersed silver powder according to any one of claims 1 to 3 is used to obtain the silver powder, wherein the silver powder has a particle size distribution of D 10 It is 0.81-0.85, D 50 It is 1.82-2.20, D 90 It is 2.70-2.91, the specific surface area is 0.43-0.48, and the tap density is 5.9-6.1.

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