CN115007875A - Silver powder and preparation method thereof - Google Patents
Silver powder and preparation method thereof Download PDFInfo
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- CN115007875A CN115007875A CN202210668165.0A CN202210668165A CN115007875A CN 115007875 A CN115007875 A CN 115007875A CN 202210668165 A CN202210668165 A CN 202210668165A CN 115007875 A CN115007875 A CN 115007875A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
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Abstract
The application provides a preparation method of silver powder, which comprises the following steps: reacting the silver ingot with nitric acid to obtain silver nitrate aqueous solution; adding a reducing agent and a dispersing agent into the silver nitrate aqueous solution for reaction, and filtering to obtain silver powder; the silver nitrate aqueous solution contains excessive nitric acid, wherein the mass ratio of the excessive nitric acid to silver ions in the silver nitrate is less than or equal to 25%. The application also provides the silver powder prepared by the preparation method. According to the silver powder preparation method, the silver ingot is dissolved by using excessive nitric acid, and then silver nitrate water solution containing excessive nitric acid is used for preparing silver powder, so that the use of high-price silver nitrate crystals is avoided, and the cost is saved. On the other hand, the silver powder prepared by the method has uniform particle size distribution, so that the application of the solar cell paste can be met.
Description
Technical Field
The application belongs to the technical field of materials, and particularly relates to silver powder and a preparation method thereof.
Background
As a conductive paste used in electrodes of solar cells and circuits of electronic parts, silver powder, glass frit, and an organic vehicle are mixed together to form a paste. In order to increase the light receiving area of the photovoltaic cell and improve the power generation efficiency, the silver powder used in the conductive paste is required to be capable of properly reducing the particle size and to make the particle size distribution more concentrated corresponding to the thinning of the fine grid electrode.
In addition, the paste has high fluidity because screen printing is used when printing the solar cell, and low-temperature sintering is more likely to be performed in order to prevent warping of the cell sheet during sintering.
The conductive silver powder is produced by adding an alkali to an aqueous solution in which a silver salt is dissolved to produce a silver oxide slurry, and then adding a reducing agent to reduce and precipitate silver particles. Or adding a complexing agent to generate a silver complex aqueous solution, and then adding a reducing agent to reduce and separate out silver particles. After the deposition of the silver powder, the silver paste is filtered, washed, dehydrated and dried, and then further processed by classification in order to adjust the particle size and particle size distribution.
Reference 1 shows the use of physical methods, volume 39, No. 9 (1970), P.861 for controlling the particle size of silver powder by precipitation method and for providing a puddle gauge.
For example, patent document 1 discloses a method for producing a metal ammonium complex solution by dissolving a solid of a metal nitrate or a metal sulfate in water or adding aqueous ammonia, and in examples, a method for producing a metal ammonium complex solution by dissolving an aqueous silver nitrate solution, adding the aqueous solution dropwise, further adding a reducing agent L-ascorbic acid and a dispersant polyvinylpyrrolidone (PVP), and adjusting the pH of the solution by adding aqueous ammonia, and patent document 2 discloses a method for producing a metal ammonium complex solution by adding a nanosized metal seed crystal (core) or an oxidizing agent solution in which 0.01 to 1.0% by weight of the metal nitrate or sulfate corresponds to one or more kinds of metal nitrates or sulfates or mixtures of metal oxides, using polyvinylpyrrolidone PVP as the dispersant. According to all the examples of the silver powder, there is proposed a silver powder production method in which aqueous ammonia is added to an aqueous solution in which a silver nitrate solid is dissolved to obtain a silver-ammonia solution, and a reducing agent is added, and the reaction is carried out using aqueous ammonia.
In addition, patent document 3, CN192594A, uses silver nitrate crystals as a method for producing a highly crystalline silver powder. Silver nitrate (100 parts by weight) is a production method for obtaining highly crystalline silver powder (5 to 60 parts by weight of polyvinylpyrrolidone) and nitric acid (35 to 70 parts by weight of nitric acid), but a production method having a high nitric acid content is often used in order to obtain highly crystalline silver powder. In all the examples, these are production methods in which silver nitrate crystals are dissolved in water. Therefore, at present, no prior art for preparing a solution by dissolving silver ingots with nitric acid exists, and the cost for using precipitated silver nitrate crystals is high. However, in order to dissolve silver ingots in nitric acid in a short time, it is necessary to use an excessive amount of nitric acid for dissolution. Thus, both aqueous silver nitrate solution and residual nitric acid are present. Such residual nitric acid affects particle control, and thus any particle size cannot be produced. Therefore, silver powder has been conventionally produced by dissolving silver nitrate crystals, which have no residual nitric acid, in water using silver nitrate crystals.
Disclosure of Invention
In order to solve the problems in the prior art, the application provides silver powder and a preparation method thereof.
Specifically, the present application relates to the following aspects:
a method for preparing silver powder, comprising the steps of:
reacting the silver ingot with nitric acid to obtain silver nitrate aqueous solution;
adding a reducing agent and a dispersing agent into the silver nitrate aqueous solution for reaction, and filtering to obtain silver powder;
the silver nitrate aqueous solution contains excessive nitric acid, wherein the mass ratio of the excessive nitric acid to silver ions in the silver nitrate is less than or equal to 25%.
Optionally, the mass ratio of excess nitric acid to silver ions in the silver nitrate is 0-20%.
Optionally, the reducing agent is one or more selected from glucose, formalin, hydrazine hydrate compound, hydroquinone, ascorbic acid, and hydrogen peroxide, and is preferably L-ascorbic acid.
Optionally, the dispersant is one or more selected from a polymeric dispersant, a fatty acid salt, a surfactant, an organometallic compound, and a chelating agent.
Optionally, the equivalent ratio of the reducing agent to the silver nitrate in the aqueous silver nitrate solution is 1.01 to 1.3.
Optionally, the temperature of the silver ingot reacted with the nitric acid is 50-130 ℃.
Optionally, adding a reducing agent and a dispersing agent into the silver nitrate aqueous solution for reaction comprises the following steps:
and adding a reducing agent into the silver nitrate aqueous solution for reaction, and then adding a dispersing agent into the reaction solution.
Optionally, the silver powder is prepared by the preparation method.
Optionally, the silver powder has a particle size D5 of 1 μm to 2 μm, D50 of 1 μm to 3 μm, D95 of 3 μm to 6 μm, and D95/D5 of 2 to 3.3.
Optionally, the change rate of the particle size D50 of the silver powder after being disintegrated is-20% -0 relative to the particle size D50 before being disintegrated.
According to the silver powder preparation method, the silver ingot is dissolved by using excessive nitric acid, and then silver nitrate water solution containing excessive nitric acid is used for preparing silver powder, so that the use of high-price silver nitrate crystals is avoided, and the cost is saved. On the other hand, the silver powder prepared by the method has uniform particle size distribution, so that the application of the solar cell paste can be met.
Detailed Description
The present application is further described below in conjunction with the following examples, which are intended to be illustrative and explanatory only and are not restrictive of the application.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Although methods and materials similar or equivalent to those described herein can be used in experimental or practical applications, the materials and methods are described below. In case of conflict, the present specification, including definitions, will control, and the materials, methods, and examples are illustrative only and not intended to be limiting. The present application is further described with reference to the following specific examples, which should not be construed as limiting the scope of the present application.
The application provides a preparation method of silver powder, which comprises the following steps:
the method comprises the following steps: reacting the silver ingot with nitric acid to obtain silver nitrate aqueous solution; wherein the silver nitrate aqueous solution contains excessive nitric acid, and the mass ratio of the excessive nitric acid to silver ions in the silver nitrate is less than or equal to 25%.
Step two: and adding a reducing agent and a dispersing agent into the silver nitrate aqueous solution for reaction, and filtering to obtain the silver powder.
In step one, the silver ingot may take any form, preferably in the form of a readily reactive granular form. The dissolution of silver ingots with nitric acid usually takes a long time, and the dissolution may be accelerated by raising the temperature for accelerating the dissolution, or by accelerating the flow of a liquid by adding a gas such as air.
In one embodiment, the temperature of the reaction of the silver ingot with nitric acid is 50 to 130 deg.C, for example, 50 deg.C, 55 deg.C, 60 deg.C, 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, 90 deg.C, 95 deg.C, 100 deg.C, 105 deg.C, 110 deg.C, 115 deg.C, 120 deg.C, 125 deg.C, and 130 deg.C. .
Furthermore, the reaction of the silver ingot with nitric acid does not require complete dissolution of the silver ingot. If the unreacted silver ingots exist, the silver nitrate aqueous solution can be obtained only by filtering the unreacted silver ingots.
The silver nitrate aqueous solution usually contains unreacted excess nitric acid, the amount of the excess nitric acid can be confirmed by sodium hydroxide titration, and the mass ratio of the excess nitric acid to silver ions in the silver nitrate is less than or equal to 25%. For example, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0% may be used.
In a specific embodiment, the mass ratio of excess nitric acid to silver ions in the silver nitrate is 0-20%. For example, it may be 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.
In the second step, when the reducing agent and the dispersing agent are added to the silver nitrate aqueous solution for reaction, the adding mode and the sequence of the silver nitrate aqueous solution, the reducing agent and the dispersing agent are not limited. For example, the following may be adopted:
(1) adding a dispersant solution, and adding a silver nitrate aqueous solution and a reducing agent aqueous solution while stirring.
(2) Reducing agent and dispersant are added into water, and silver nitrate solution is added while stirring.
(3) Adding silver nitrate water solution and dispersant, stirring and adding reducer water solution.
(4) Adding silver nitrate water solution and reducing agent for reaction, and adding dispersant into the reaction solution after the reaction.
Wherein the silver nitrate in the silver nitrate aqueous solution and the reducing agent can react at any molar ratio. In a particular embodiment, the equivalent ratio of the reducing agent to the silver nitrate in the aqueous silver nitrate solution is 1.01 to 1.3, and may be, for example, 1.01, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3. In this application, equivalent means the number of moles x (number of elements of acid or base), for a base, 1 equivalent is the number of moles of base that react with 1 mole of hydrogen ion, and for an acid, 1 equivalent is the number of moles of acid that will provide 1 mole of hydrogen ion. For example, when the reducing agent is a single-component, the equivalent ratio of the reducing agent to the silver nitrate in the aqueous silver nitrate solution is the molar ratio of the reducing agent to the silver nitrate in the aqueous silver nitrate solution, i.e., the molar ratio of the reducing agent to the silver nitrate in the aqueous silver nitrate solution is 1.01 to 1.3. When the reducing agent is binary, the molar ratio of the reducing agent to the silver nitrate in the aqueous silver nitrate solution is 1/2 (1.01-1.3).
The reducing agent may be any reducing agent capable of reducing silver nitrate to obtain silver particles.
In a specific embodiment, the reducing agent is selected from one or more of glucose, formalin, hydrazine hydrate compounds, hydroquinone, ascorbic acid, and hydrogen peroxide, and is preferably L-ascorbic acid.
The dispersant is one or more selected from polymer dispersant, fatty acid salt, surfactant, organic metal compound and chelating agent.
Among them, examples of the polymeric dispersant include PVP (polyvinylpyrrolidone), polyvinyl alcohol, polyethyleneimine, polyacrylamide, polyallylamine, gelatin, peptide, collagen peptide, albumin, gum arabic, and the like.
Examples of the fatty acid dispersing agent include palmitic acid, stearic acid, arachidic acid, behenic acid, palmitoleic acid, oleic acid, elaidic acid, guava acid, erucic acid, ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid and the like, fatty acids of C16 or more, and the like.
Examples of fatty acid salts include salts formed from metals such as lithium, sodium, potassium, magnesium, calcium, strontium, barium, aluminum, iron, cobalt, nickel, copper, silver, gold, zinc, tin, and fatty acids.
Examples of the surfactant include anionic surfactants such as alkylbenzenesulfonates and polyoxyethylene alkyl ether phosphates, cationic surfactants such as aliphatic 4-stage ammonium salts, amphoteric surfactants such as imidazolines, and nonionic surfactants such as polyoxyethylene fatty acid esters, including, for example, tetraisocyanate, tetramethylsilane, tetramethoxysilane, tetramethyldisiloxane, hexamethyldisiloxane, silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and the like. Examples of chelating agents are triazoles such as imidazole, thiazole, benzotriazole, 1H-1,2, 3-triazole and salts thereof such as sodium benzotriazole, or oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, glycolic acid, lactic acid, hydroxybutyric acid, glyceric acid, tartaric acid, malic acid, hydroxymalonic acid, hydroacrylic acid, mader's acid, citric acid and the like.
And the silver powder obtained in the second step can be further washed by deionized water.
The application also provides silver powder which is prepared by the preparation method.
The prepared silver powder can be characterized by D5, D50 and D95, and the change rate of the particle size D50 of the silver powder after being disintegrated relative to the particle size D50 before being disintegrated.
Wherein D5, D50 and D95 are parameters for characterizing the particle size and represent the values of 5%, 50% and 95% of the particles in the measured size.
D5: the cumulative particle distribution is 5% of the particle size, i.e. the volume fraction of particles smaller than this is 5% of the total particles.
D50: the particle cumulative distribution is 50% of the particle size. Also called median diameter or median diameter, is a typical value for the size of the particle size, which accurately divides the population into two equal parts, that is to say 50% of the particles exceed this value and 50% of the particles fall below this value. If D50 of a sample is 5 μm, it indicates that of all the particle sizes constituting the sample, particles larger than 5 μm account for 50% and particles smaller than 5 μm also account for 50%.
D95: the particle cumulative distribution was 95% particle size. I.e. the volume content of particles smaller than this size is 95% of the total particles.
The rate of change of the particle diameter D50 after silver powder shattering from the particle diameter D50 before silver powder shattering means the particle diameter D50 after silver powder shattering-the particle diameter D50 before silver powder shattering)/the particle diameter D50 before silver powder shattering.
The disintegration described herein refers to a process of separating soft agglomerates of the dried silver powder by physical high-speed collision using a tool, and can be usually disintegrated using a disintegrator. Instead of disintegrating, the particles may be dispersed by flow and mechanical collision of the silver particles.
Herein, the particle size distribution of the silver powder, including D5, D50, and D95, can be measured by a particle size distribution measuring apparatus (Mastersizer 3000 by Malvern, using conditions (refractive index 0.14, absorption 3.99).
The silver powder prepared by the application has the D5 of 1-2 μm, the D50 of 1-3 μm, the D95 of 3-6 μm and the D95/D5 of 2-3.3.
Furthermore, the change rate of the particle size D50 after silver powder is broken is-20% -0 relative to the particle size D50 before the silver powder is broken, and can be-20%, -19%, -18%, -17%, -16%, -15%, -14%, -13%, -12%, -11%, -10%, -9%, -8%, -7%, -6%, -5%, -4%, -3%, -2%, -1%, for example.
According to the silver powder preparation method, the silver ingot is dissolved by using the excessive nitric acid with the mass ratio of silver ions in the silver nitrate being less than or equal to 25%, and then the silver powder is prepared by using the silver nitrate water solution containing the excessive nitric acid, so that the use of expensive silver nitrate crystals is avoided, and the cost is saved. On the other hand, the silver powder prepared by the method has the particle size D5 of 1-2 μm, the particle size D50 of 1-3 μm, the particle size D95 of 3-6 μm and the particle size D95/D5 of 2-3.3, and the change rate of the particle size D50 after the silver powder is disintegrated relative to the particle size D50 before disintegration is-20-0. The closer the rate of change of the particle diameter D50 after the silver powder was disintegrated to 0 with respect to the particle diameter D50 before the disintegration, the more uniform the particle size distribution of the obtained silver powder was demonstrated. The change rate of the particle size D50 of the silver powder prepared by the method after being disintegrated is more than-20% and even more than-13% relative to the particle size D50 before being disintegrated, and the silver powder has uniform particle size distribution, so that the application of the solar cell slurry can be met.
Examples
Example 1
(1) In a 500ml beaker was placed 216g of silver ingot (granular) followed by 150ml of deionized water and warmed with an electric furnace. Concentrated nitric acid is dripped when the temperature is over 50 ℃. During 40 minutes of NOx gas generation, 125.8g of nitric acid was charged. The temperature was 85 ℃. Continuously heating to 95-105 ℃, and adding water.
After cooling, the obtained silver nitrate aqueous solution was filtered, dried and the undissolved silver was measured, and the amount of the obtained silver nitrate liquid was measured to obtain a silver concentration of 113 g/L. Further, the amount of residual nitric acid in the silver nitrate aqueous solution was confirmed by titration with sodium hydroxide. The residual amount of silver nitrate was 7.7 parts by mass of residual nitric acid per 100 parts by mass of silver ions.
The silver concentration of the obtained silver nitrate aqueous solution, the ratio of the mass of the residual nitric acid to the mass of silver nitrate are shown in table 1.
(2) In a beaker, 30g of PVP molecular weight 44000-54000 (PVP Kollidon30 manufactured by BASF) and 100g of ascorbic acid (vitamin C manufactured by Shiyao Kagaku) were taken in accordance with the silver ratio, dissolved in 3000ml of water, and stirred at 160 rpm. 900ml of the silver nitrate aqueous solution and the ascorbic acid 111g/L reducing aqueous solution prepared in the step (1) of 900ml of silver concentration was dropped into the beaker at a flow rate of 160ml/min while being 900 ml. After the completion of the dropwise addition, stearic acid, a dispersant, was dissolved in ethanol, and added in an amount of 0.1% based on the amount of silver with stirring. After 5 minutes, the reaction solution was filtered, 5L of washing water was added thereto to confirm that the conductivity was less than 20. mu.s/cm, dehydrated, and the wet powder was sampled and the particle size distribution was measured by a particle size distribution measuring instrument. Specifically, the measurement was performed by a particle size distribution measuring apparatus (Mastersizer 3000 by Malvern, using conditions (refractive index 0.14, absorption 3.99).
And (3) putting the dehydrated silver powder into a drying oven at 90 ℃, and after confirming that the silver powder is dried, breaking the powder by using a breaker. After the disintegration was completed, a sample was taken and the particle size distribution was measured.
Example 2
Example 2 is different from example 1 only in that the mass ratio of the residual nitric acid in the prepared silver nitrate aqueous solution to the silver ions in the silver nitrate is 12.8% by adjusting the reaction temperature of the silver ingot and the nitric acid in step (1). The operation of step (2) was the same as in example 1.
Through determination, the residual amount of silver nitrate is 12.8 parts by mass of residual nitric acid per 100 parts by mass of silver ions.
The silver concentration, the residual nitric acid and the mass ratio of silver nitrate of the obtained silver nitrate aqueous solution are shown in table 1.
Example 3
Example 3 is different from example 1 only in that the mass ratio of the residual nitric acid in the prepared silver nitrate aqueous solution to the silver ions in the silver nitrate is 20.4% by adjusting the reaction temperature of the silver ingot and the nitric acid in step (1). The operation of step (2) was the same as in example 1.
The residual amount of silver nitrate was determined to be 20.4 parts by mass of residual nitric acid per 100 parts by mass of silver ions.
The silver concentration, the residual nitric acid and the mass ratio of silver nitrate of the obtained silver nitrate aqueous solution are shown in table 1. Example 4
Example 4 is different from example 1 only in that the mass ratio of the residual nitric acid in the prepared silver nitrate aqueous solution to the silver ions in the silver nitrate is 5% by adjusting the reaction temperature of the silver ingot and the nitric acid in step (1). The operation of step (2) was the same as in example 1.
The residual amount of silver nitrate is determined to be 5 parts by mass of residual nitric acid per 100 parts by mass of silver ions.
The silver concentration, the residual nitric acid and the mass ratio of silver nitrate of the obtained silver nitrate aqueous solution are shown in table 1.
Comparative example 1
Comparative example 1 is different from example 1 only in that the mass ratio of the residual nitric acid in the prepared silver nitrate aqueous solution to the silver ions in the silver nitrate was 25.6% by adjusting the reaction temperature of the silver ingot and the nitric acid in step (1). The operation of step (2) was the same as in example 1.
Through determination, the residual amount of silver nitrate is 25.6 parts by mass of residual nitric acid per 100 parts by mass of silver ions.
The silver concentration, the residual nitric acid and the mass ratio of silver nitrate of the obtained silver nitrate aqueous solution are shown in table 1.
Comparative example 2
Comparative example 2 is different from example 1 only in that the mass ratio of the residual nitric acid in the prepared silver nitrate aqueous solution to the silver ions in the silver nitrate was 41% by adjusting the reaction temperature of the silver ingot and the nitric acid in step (1). The operation of step (2) was the same as in example 1.
The residual amount of silver nitrate was determined to be 41 parts by mass of residual nitric acid per 100 parts by mass of silver ions.
The silver concentration, the residual nitric acid and the mass ratio of silver nitrate of the obtained silver nitrate aqueous solution are shown in table 1.
TABLE 1
Claims (10)
1. A method for preparing silver powder, characterized in that the method comprises the following steps:
reacting the silver ingot with nitric acid to obtain silver nitrate aqueous solution;
adding a reducing agent and a dispersing agent into the silver nitrate aqueous solution for reaction, and filtering to obtain silver powder;
the silver nitrate aqueous solution contains excessive nitric acid, wherein the mass ratio of the excessive nitric acid to silver ions in the silver nitrate is less than or equal to 25%.
2. The production method according to claim 1, wherein the mass ratio of the excess nitric acid to silver ions in the silver nitrate is 0 to 20%.
3. The method according to claim 1, wherein the reducing agent is one or more selected from glucose, formalin, hydrazine hydrate compounds, hydroquinone, ascorbic acid, and hydrogen peroxide, and preferably is L-ascorbic acid.
4. The method according to claim 1, wherein the dispersant is one or more selected from the group consisting of a polymer dispersant, a fatty acid salt, a surfactant, an organic metal compound, and a chelating agent.
5. The method according to claim 1, wherein an equivalent ratio of the reducing agent to silver nitrate in the aqueous silver nitrate solution is 1.01 to 1.3.
6. The method of claim 1, wherein the temperature of the silver ingot reacted with the nitric acid is 50 to 130 ℃.
7. The method for preparing according to claim 1, wherein adding a reducing agent and a dispersing agent to the silver nitrate aqueous solution to perform a reaction comprises the steps of:
and adding a reducing agent into the silver nitrate aqueous solution for reaction, and then adding a dispersing agent into the reaction solution.
8. A silver powder, characterized in that the silver powder is produced by the production method according to any one of claims 1 to 6.
9. The silver powder according to claim 8, wherein the particle diameter D5 of the silver powder is 1 μm to 2 μm, D50 is 1 μm to 3 μm, D95 is 3 μm to 6 μm, and D95/D5 is 2 to 3.3.
10. The silver powder according to claim 8, wherein the rate of change of the particle diameter D50 of the silver powder after being disintegrated is-20% to 0 with respect to the particle diameter D50 thereof before being disintegrated.
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| WO2023240825A1 (en) * | 2022-06-14 | 2023-12-21 | 江苏连银新材料有限公司 | Silver powder and preparation method therefor |
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| CN115007875A (en) * | 2022-06-14 | 2022-09-06 | 江苏连银新材料有限公司 | Silver powder and preparation method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2023240825A1 (en) * | 2022-06-14 | 2023-12-21 | 江苏连银新材料有限公司 | Silver powder and preparation method therefor |
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| WO2023240825A1 (en) | 2023-12-21 |
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