Silver particles, their preparation method and application

Abstract

This invention discloses a silver particle, its preparation method, and its applications, belonging to the field of metallic materials. The silver particles provided by this invention comprise the following raw materials: silver salt, reducing agent, silver seed crystals, organic amine coating agent, dispersant, and flocculant, wherein the organic amine coating agent has a carbon number greater than or equal to 6. This invention utilizes the combination of the organic amine coating agent with other raw materials to obtain silver particles with regular shape, narrow particle size distribution, good dispersibility, large specific surface area, and good sintering performance. This is beneficial for improving the density, mechanical strength, electrical conductivity, and photoelectric properties of the sintered silver body. The silver particles or sintered silver body obtained by this invention have wide applications in the preparation of electronic materials, photovoltaic cell materials, pharmaceutical materials, or catalytic materials.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials, and particularly relates to a silver particle, its preparation method, and its application. Background Technology

[0002] In modern electronics and energy industries, conductive pastes play an increasingly important role. For example, in the photovoltaic field, conductive pastes are indispensable materials in photovoltaic cell production, primarily used to prepare the front and back electrodes of the cells for collecting and transmitting current. With the rapid development of photovoltaic energy, the demand for conductive pastes is also continuously increasing. Conductive pastes are mainly composed of high-purity silver powder, glass systems, and organic carriers. Silver powder accounts for 70-90% of the cost of photovoltaic silver paste; therefore, the performance of silver powder significantly affects the conductive paste. Among these, the specific surface area of ​​silver powder is a crucial parameter for measuring the particle size of silver powder and has a significant impact on its performance. Increasing the specific surface area of ​​silver powder is beneficial for improving conductivity, sintering performance, activity, and optimizing the printability, adhesion, and density of the silver powder paste. How to improve the specific surface area of ​​silver powder is one of the current research focuses.

[0003] Silver powder preparation methods are mainly divided into two categories: physical methods and chemical methods. Physical methods mainly include mechanical ball milling and evaporation-condensation. However, the disadvantages of mechanical ball milling are that the silver powder produced has a wide particle size distribution and irregular shape, which may introduce impurities. Evaporation-condensation has low production efficiency and cannot be used for large-scale production. Therefore, there is an urgent need to find a silver particle with a large specific surface area, regular shape, simple preparation process, and low cost. Summary of the Invention

[0004] In order to overcome at least one of the problems existing in the prior art, one of the objectives of the present invention is to provide a silver particle having a large specific surface area, good electrical conductivity and sintering performance.

[0005] The second objective of this invention is to provide a method for preparing the above-mentioned silver particles.

[0006] The third objective of this invention is to provide a silver sintered body.

[0007] The third objective of this invention is to provide an application of the above-mentioned silver particles or silver sintered bodies.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A first aspect of the present invention provides silver particles comprising the following raw materials: silver salt, reducing agent, silver seed crystals, organic amine coating agent, dispersant, and flocculant, wherein the organic amine coating agent has a carbon number greater than or equal to 6.

[0010] The reaction mechanism of this invention mainly utilizes a reducing agent to reduce silver salt to silver atoms, and then allows the silver atoms to attach to silver seed crystals to grow into silver particles. In this invention, an organic amine coating agent is used as one of the raw materials for preparing silver particles. Combined with other raw materials, this facilitates the formation of a polymer network with a through-pore structure through a cross-linking reaction during the preparation of silver particles. This structure helps organic raw materials to be quickly released during the sintering of silver particles without remaining in the silver particles and affecting the sintering performance, thereby improving the sintering activity and sintering shrinkage rate of the silver particles.

[0011] Preferably, the organic amine coating agent has 6 to 30 carbon atoms; more preferably, the organic amine coating agent has 7 to 28 carbon atoms; and even more preferably, the organic amine coating agent has 8 to 25 carbon atoms.

[0012] Preferably, the organic amine coating agent includes at least one of octylamine, hexadecylamine, octadecylamine, trihexylamine, dihydroxyethyl oleylamine, diallylamine, or triisopropanolamine; more preferably, the organic amine coating agent includes at least one of octylamine, dihydroxyethyl oleylamine, diallylamine, or triisopropanolamine; even more preferably, the organic amine coating agent includes dihydroxyethyl oleylamine, triisopropanolamine, or a combination thereof.

[0013] In some specific embodiments of the present invention, the organic amine coating agent is selected from triisopropanolamine.

[0014] Preferably, the reducing agent includes at least one of ascorbic acid, citric acid, sodium citrate, potassium citrate, or glucose; more preferably, the reducing agent includes at least one of ascorbic acid, sodium citrate, or glucose; even more preferably, the reducing agent is selected from ascorbic acid.

[0015] In some specific embodiments of the present invention, the reducing agent is used as a preparation raw material in the form of a solution.

[0016] In some specific embodiments of the present invention, the solvent of the reducing agent solution is water.

[0017] Preferably, the silver salt comprises at least one of silver nitrate, silver fluoride, silver chlorate, or silver perchlorate; more preferably, the silver salt comprises at least one of silver nitrate, silver chlorate, or silver perchlorate; even more preferably, the silver salt is selected from silver nitrate.

[0018] In some specific embodiments of the present invention, the silver salt is used as a preparation raw material in the form of a solution.

[0019] In some specific embodiments of the present invention, the solvent of the silver salt solution is water.

[0020] Preferably, the silver ion concentration of the silver salt solution is 0.01–5 mol / L; more preferably, it is 0.03–4.5 mol / L; and even more preferably, it is 0.08–2 mol / L.

[0021] Preferably, the dispersant comprises at least one of polysorbate, polyacrylic acid, or styrene-maleic acid; more preferably, the dispersant is selected from polysorbate.

[0022] Preferably, the polysorbate includes at least one of polysorbate 20, polysorbate 40, polysorbate 60 or polysorbate 80; more preferably, the polysorbate is selected from polysorbate 60.

[0023] Preferably, the flocculant includes at least one of lauric acid, sodium laurate, potassium laurate, or stearic acid; more preferably, the flocculant includes at least one of lauric acid, sodium laurate, or stearic acid; even more preferably, the flocculant is selected from sodium laurate.

[0024] Preferably, the average particle size of the silver seed crystals is 100–300 nm; more preferably 150–250 nm; and even more preferably 150–200 nm.

[0025] Preferably, the silver content of the silver seed crystal is 1-15 wt%; more preferably 3-10 wt%; and even more preferably 4-8 wt%.

[0026] Preferably, the molar ratio of the reducing agent to the silver ions in the silver salt is (0.1-3):1; more preferably (0.4-2.5):1; and even more preferably (0.5-2):1.

[0027] Preferably, the molar ratio of the organic amine coating agent to the silver ions in the silver salt is (0.005-0.4):1; more preferably (0.01-0.35):1; and even more preferably (0.05-0.3):1.

[0028] Preferably, the mass ratio of the dispersant to the silver ions in the silver salt is (0.005-0.06):1; more preferably (0.008-0.055):1; and even more preferably (0.01-0.05):1.

[0029] Preferably, the mass ratio of the flocculant to the silver ions in the silver salt is (0.0005-0.03):1; more preferably (0.001-0.02):1; and even more preferably (0.001-0.01):1.

[0030] Preferably, the mass ratio of silver in the silver seed crystal to silver ions in the silver salt is (0.001-0.02):1; more preferably (0.003-0.015):1; and even more preferably (0.005-0.01):1.

[0031] Preferably, the average particle size of the silver particles is 1–5 μm; more preferably 1.5–4 μm; and even more preferably 2–3 μm.

[0032] Preferably, the specific surface area of ​​the silver particles is ≥0.7m². 2 / g; more preferably 0.7–2m 2 / g; more preferably 0.7~1m 2 / g.

[0033] Preferably, the tap density of the silver particles is ≥5 g / cm³. 3 Further preferred values ​​are 5–10 g / cm³. 3 .

[0034] Preferably, the silver particles have a through-hole structure inside.

[0035] A second aspect of the present invention provides a method for preparing the silver particles described in the first aspect of the present invention, comprising the following steps: mixing the raw materials and carrying out a reduction reaction, and obtaining the silver particles after precipitation.

[0036] Preferably, the mixing method is selected from stirring.

[0037] Preferably, the stirring speed is 120–480 r / min; more preferably 150–450 r / min; and even more preferably 180–410 r / min.

[0038] Preferably, the drying temperature is 30–140°C; more preferably 40–120°C; and even more preferably 55–95°C.

[0039] Preferably, the drying time is 0.5 to 15 hours; more preferably 1 to 12 hours; and even more preferably 4 to 9 hours.

[0040] Preferably, the method for preparing the silver particles specifically includes the following steps: first, mixing silver seed crystals, reducing agent and organic amine coating agent, then adding silver salt and dispersant to carry out a reduction reaction, and finally adding flocculant to carry out precipitation to obtain the silver particles.

[0041] In some specific embodiments of the present invention, the precipitation process further includes the following steps: solid-liquid separation to obtain a precipitate, drying the precipitate to obtain the silver particles.

[0042] A third aspect of the present invention provides a silver sintered body obtained by sintering silver particles comprising those described in the first aspect of the present invention.

[0043] The silver particles of the first aspect of the present invention have good sintering performance, especially good sintering activity and sintering shrinkage. The silver sintered body obtained by sintering them has good density, high mechanical strength, and good chemical reactivity, electrical conductivity and photoelectric conversion efficiency.

[0044] The fourth aspect of the present invention provides the application of the silver particles described in the first aspect of the present invention, or the silver sintered body described in the third aspect of the present invention, in the preparation of electronic materials, photovoltaic cell materials, pharmaceutical materials, or catalytic materials.

[0045] In some specific embodiments of the present invention, the electronic material includes at least one of wires, circuit boards, capacitors, resistors, or conductive films.

[0046] In some specific embodiments of the present invention, the photovoltaic cell material includes a photovoltaic electrode.

[0047] In some specific embodiments of the present invention, the medical material includes at least one of implantable material, drug delivery material, stent material, or medical adhesive material.

[0048] In some specific embodiments of the present invention, the catalytic material includes a catalyst, a catalyst support, or a combination thereof.

[0049] The beneficial effects of this invention are: by utilizing organic amine coating agents in combination with other raw materials, the silver particles obtained by this invention have regular shapes, narrow particle size distribution, good dispersibility, large specific surface area, and good sintering performance, which is beneficial to improving the density, mechanical strength, electrical conductivity, and photoelectric properties of the silver sintered body. The silver particles or silver sintered bodies obtained by this invention have wide applications in the preparation of electronic materials, photovoltaic cell materials, pharmaceutical materials, or catalytic materials.

[0050] Specifically, compared with the prior art, the present invention has the following advantages:

[0051] 1. The silver particles obtained by this invention have a large specific surface area and small particle size, which is beneficial to increasing the contact area between silver particles and thus improving conductivity. Furthermore, the large specific surface area of ​​the silver particles makes them easier to combine together during the sintering process, thereby forming a denser sintered body structure, which improves the mechanical strength and conductivity of the sintered body.

[0052] 2. Silver particles with high specific surface area exhibit higher activity, which is beneficial for increasing their reaction rate in chemical reactions. For example, in the field of photovoltaic cells, silver particles with high specific surface area are beneficial for improving the conductivity of the electrodes, thereby increasing the photoelectric conversion efficiency.

[0053] 3. In the preparation of conductive silver paste, silver particles with high specific surface area can improve the printability, adhesion and density of the paste.

[0054] 4. Due to the high activity and conductivity of silver particles with high specific surface area, the amount of silver particles used can be reduced, thus lowering costs and facilitating large-scale industrial applications. Attached Figure Description

[0055] Figure 1 This is a SEM image of the silver particles from Example 1.

[0056] Figure 2 This is a SEM image of the silver particles from Example 2.

[0057] Figure 3 This is a SEM image of the silver particles from Example 3.

[0058] Figure 4 This is a SEM image of the silver particles from Example 4.

[0059] Figure 5 This is a SEM image of the silver particles from Example 5.

[0060] Figure 6 This is a SEM image of the silver particles in Comparative Example 1.

[0061] Figure 7 The image shows the SEM image of the silver particles in Comparative Example 2.

[0062] Figure 8 This is a SEM image of the silver particles in Comparative Example 3.

[0063] Figure 9 This is a SEM image of the silver particles in Comparative Example 4.

[0064] Figure 10 This is a SEM image of the silver particles in Comparative Example 5. Detailed Implementation

[0065] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0066] Example 1

[0067] A type of silver particle is prepared by the following steps:

[0068] S1. Add 128.6675 mL of deionized water to a 250 mL beaker, add 2.6 g of ascorbic acid (VC) solution, start stirring (350 rpm), then add 27 μL of nano silver seed solution (silver content is 4.5 wt%, and the average particle size of silver seeds is 175 nm), and then immediately add 0.6056 g of triisopropanolamine solution to obtain mixture S1;

[0069] S2. Add 0.069 g of polysorbate 60 solution to the S1 mixture, and then immediately add 8 mL of silver nitrate solution and stir to obtain the S2 mixture;

[0070] S3. Add 0.0138g of sodium lauryl sulfate to the mixture of S2 and stir for 15min. Then, perform solid-liquid separation, washing, and drying (drying temperature is 55℃, drying time is 4.5h) to obtain silver particles.

[0071] The above-mentioned solution preparation process is as follows:

[0072] Silver nitrate solution: 5g of solid silver nitrate was dissolved in 18.5mL of deionized water. Since 128.6675mL of deionized water was added to the beaker beforehand, the silver ion concentration in the prepared silver nitrate solution was 0.2mol / L. 8mL of the silver nitrate solution was taken, so the amount of silver ions added to the reaction system was 1.6 × 10⁻⁶. -3 mol.

[0073] VC solution: In the VC solution, the mass fraction of VC is 6.5%, and the molar ratio of VC to silver ions in the reaction system is 0.6:1;

[0074] Polysorbate 60 solution: In the polysorbate 60 solution, the mass fraction of polysorbate 60 is 5%, and the mass ratio of dispersant to silver ions in the reaction system is 0.02:1;

[0075] Preparation of triisopropanolamine solution: The mass fraction of triisopropanolamine in the triisopropanolamine solution is 5%, and the molar ratio of triisopropanolamine to silver ions in the reaction system is 0.1:1;

[0076] Preparation of sodium laurate solution: The sodium laurate solution contains 2.5% sodium laurate by mass, and the mass ratio of sodium laurate to silver ions in the reaction system is 0.002:1;

[0077] Preparation of the nano-silver seed solution: The silver content of the nano-silver seed solution is 4.5 wt%, and the mass ratio of silver content to silver ions in the reaction system is 0.007:1.

[0078] Example 2

[0079] A type of silver particle, compared with Example 1, the silver ion concentration of the silver nitrate solution in this example is 0.1 mol / L, and the other raw materials and preparation methods are the same as in Example 1.

[0080] Example 3

[0081] A silver particle, compared with Example 1, in this example, the molar ratio of VC to silver ions in the reaction system is 1.2:1, and other raw materials and preparation methods are the same as in Example 1.

[0082] Example 4

[0083] A silver particle, compared with Example 1, in this example, the molar ratio of polysorbate 60 to silver ions in the reaction system is 1.2:1, and other raw materials and preparation methods are the same as in Example 1.

[0084] Example 5

[0085] A type of silver particle, compared with Example 1, in this example, the mass ratio of sodium lauryl ion to silver ion in the reaction system is 0.001:1, and other raw materials and preparation methods are the same as in Example 1.

[0086] Comparative Example 1

[0087] A type of silver particle, compared with Example 1, in this example the triisopropanolamine solution is replaced with acetic acid solution, and other raw materials and preparation methods are the same as in Example 1.

[0088] Comparative Example 2

[0089] A type of silver particle, compared with Example 1, in this example the triisopropanolamine solution is replaced with pentylamine solution, and other raw materials and preparation methods are the same as in Example 1.

[0090] Comparative Example 3

[0091] A type of silver particle, compared with Example 1, in this example the triisopropanolamine solution is replaced with ethylenediamine solution, and the other raw materials and preparation methods are the same as in Example 1.

[0092] Comparative Example 4

[0093] A type of silver particle, compared with Example 1, in this example, the molar ratio of triisopropanolamine to silver ions in the reaction system is 0.5, and other raw materials and preparation methods are the same as in Example 1.

[0094] Comparative Example 5

[0095] A type of silver particle, compared with Example 1, the stirring speed in this example is 500 rpm, and the other raw materials and preparation methods are the same as in Example 1.

[0096] Performance Characterization

[0097] The silver particles obtained in Examples 1-5 and Comparative Examples 1-5 were subjected to particle size and specific surface area tests (particle size was measured using an Anton Paar PSA instrument via the humidity measurement method; specific surface area was measured using an Anton Paar BET instrument via the static volume method), and their morphology was characterized using scanning electron microscopy. The particle size and specific surface area data are shown in Table 1, and the scanning electron microscope images are shown below. Figures 1-10 As shown, where, Figure 1 This is a SEM image of the silver particles from Example 1. Figure 2 This is a SEM image of the silver particles from Example 2. Figure 3 This is a SEM image of the silver particles from Example 3. Figure 4 This is a SEM image of the silver particles from Example 4. Figure 5 This is a SEM image of the silver particles from Example 5. Figure 6 This is a SEM image of the silver particles in Comparative Example 1. Figure 7 This is a SEM image of the silver particles in Comparative Example 2. Figure 8 The image shows a SEM image of the silver particles in Comparative Example 3. Figure 9 The image shows a SEM image of the silver particles in Comparative Example 4. Figure 10 This is a SEM image of the silver particles in Comparative Example 5.

[0098] Table 1. Particle size and specific surface area data of silver particles in Examples 1-5 and Comparative Examples 1-5.

[0099]

[0100] From Table 1 and Figures 1-10 It is evident that, compared to Comparative Examples 1-5, the silver particles in Examples 1-5 have regular shapes, good dispersibility, and larger specific surface areas. From... Figure 6 As can be seen, in Comparative Example 1, the use of acetic acid as an acidic coating agent prevented the formation of through-pore structures in the silver particles, resulting in a smaller specific surface area. From... Figures 7-8 It is evident that Comparative Examples 2 and 3, which used organic amines with short carbon chain lengths as coating agents, also struggled to form a through-pore structure, resulting in relatively small specific surface areas. Furthermore, from... Figures 9-10 It is evident that using specific dosage ratios and preparation conditions is beneficial for obtaining silver particles with larger specific surface areas.

[0101] Furthermore, the silver particles in Examples 1 to 5 exhibit good sintering activity and sintering shrinkage.

[0102] The silver particles from Examples 1 to 5 were sintered to obtain silver sintered bodies with good density, mechanical strength, electrical conductivity and photoelectric properties.

[0103] The prepared silver particles or sintered silver bodies exhibit excellent application performance as electronic materials such as wires, circuit boards, capacitors, resistors, or conductive films; photovoltaic cell materials such as photovoltaic electrodes; medical materials such as implant materials, drug delivery materials, scaffold materials, or medical adhesives; and catalytic materials such as catalysts and catalyst supports. For example, in the field of photovoltaic cells, silver particles with high specific surface area are beneficial to improving the conductivity of the electrodes, thereby increasing the photoelectric conversion efficiency. In addition, when preparing conductive silver paste, silver particles with high specific surface area can improve the printability, adhesion, and density of the paste.

[0104] The silver particles obtained in this invention have a large specific surface area and small particle size, which is beneficial for increasing the contact area between silver particles and thus improving conductivity. Furthermore, the large specific surface area of ​​the silver particles makes them easier to bond together during sintering, resulting in a denser sintered body structure, thereby improving the mechanical strength and conductivity of the sintered body. In addition, the high specific surface area silver particles obtained in this invention have higher activity, which is beneficial for increasing their reaction rate in chemical reactions. Due to the high activity and conductivity of the high specific surface area silver particles, the amount of silver particles used can be reduced, lowering costs and facilitating large-scale industrial applications.

[0105] In summary, this invention utilizes organic amine coating agents in combination with other raw materials to obtain silver particles with regular shape, narrow particle size distribution, good dispersibility, large specific surface area, and good sintering performance. This is beneficial for improving the density, mechanical strength, electrical conductivity, and photoelectric properties of the silver sintered body. The silver particles or silver sintered bodies obtained by this invention have wide applications in the preparation of electronic materials, photovoltaic cell materials, pharmaceutical materials, or catalytic materials.

Claims

1. A type of silver particle, characterized in that, The preparation materials include the following: silver salt, reducing agent, silver seed crystal, organic amine coating agent, dispersant, and flocculant, wherein the organic amine coating agent has a carbon number greater than or equal to 6; The reducing agent includes at least one of ascorbic acid, citric acid, sodium citrate, potassium citrate, or glucose; the silver salt includes at least one of silver nitrate, silver fluoride, silver chlorate, or silver perchlorate; the dispersant includes at least one of polysorbate, polyacrylic acid, or styrene-maleic acid; and the flocculant includes at least one of lauric acid, sodium laurate, potassium laurate, or stearic acid. The molar ratio of the reducing agent to the silver ions in the silver salt is (0.1~3):1; the molar ratio of the organic amine coating agent to the silver ions in the silver salt is (0.005~0.4):1; the mass ratio of the dispersant to the silver ions in the silver salt is (0.005~0.06):1; the mass ratio of the flocculant to the silver ions in the silver salt is (0.0005~0.03):1; and the mass ratio of silver in the silver seed crystals to the silver ions in the silver salt is (0.001~0.02):

1. The silver particles are prepared by a method comprising the following steps: mixing the raw materials and carrying out a reduction reaction, and obtaining the silver particles after precipitation.

2. The silver particles according to claim 1, characterized in that, The organic amine coating agent includes at least one of octylamine, hexadecylamine, octadecylamine, trihexylamine, dihydroxyethyl oleylamine, diallylamine, or triisopropanolamine.

3. The silver particles according to claim 1, characterized in that, The average particle size of the silver seeds is 100~300nm; And / or, the silver content of the silver seed crystal is 1~15wt%.

4. The silver particles according to claim 1, characterized in that, The average particle size of the silver particles is 1~5μm; And / or, the specific surface area of ​​the silver particles is ≥0.7m². 2 / g; And / or, the interior of the silver particles has a through-hole structure.

5. A method for preparing silver particles as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The raw materials are mixed and subjected to a reduction reaction, and the silver particles are obtained after precipitation. The mixing method is selected from stirring. The stirring speed is 120~480r / min.

6. A sintered body of silver particles, characterized in that, It is obtained by sintering silver particles as described in any one of claims 1 to 4.

7. The use of silver particles as described in any one of claims 1 to 4, or the sintered body of silver particles as described in claim 6, in the preparation of electronic materials, photovoltaic cell materials, medical materials, or catalytic materials; wherein the electronic materials include at least one of wires, circuit boards, capacitors, resistors, or conductive films; the photovoltaic cell materials include photovoltaic electrodes; the medical materials include at least one of implant materials, drug delivery materials, scaffold materials, or medical adhesive materials; and the catalytic materials include catalysts, catalyst supports, or combinations thereof.

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