CN115647381A - Preparation method of high-sphericity silver powder - Google Patents
Preparation method of high-sphericity silver powder Download PDFInfo
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Abstract
The application relates to the technical field of metal powder preparation, in particular to a preparation method of high-sphericity silver powder, which comprises the following steps: the mass ratio is (30-100): (0.1-5) dissolving and uniformly mixing silver nitrate and crown ether in deionized water at the temperature of 20-60 ℃ to form a solution A; mixing the following components in percentage by mass (15-70): (5-25) stirring and dissolving the reducing agent and the dispersing agent in deionized water at the temperature of 20-60 ℃ to form a solution B; adjusting the pH value of the solution B to 3-9 by using a pH regulator, and adding the solution A for reaction under the condition of heating and stirring; and after the reaction is finished, filtering the obtained silver powder slurry, washing the silver powder slurry by deionized water and ethanol until the conductivity is less than or equal to 20 mu S/cm, dispersing, filtering and drying the silver powder slurry. The coordination effect of the crown ether and the silver ions is utilized, the release rate of the silver ions in the reaction is effectively controlled, and the prepared silver powder is high in sphericity and tap density.
Description
Technical Field
The application relates to the technical field of metal powder preparation, in particular to a preparation method of high-sphericity silver powder.
Background
The silver paste prepared from the high-sphericity silver powder has the advantages of good fluidity, convenience in printing, small sintering shrinkage, compact film and the like, and is widely applied to various fields. However, the preparation difficulty of the silver powder with high sphericity is high, the silver powder with high sphericity is generally used in the market at present and is similar to spherical silver powder, and most of the prior art is that a large amount of a plurality of dispersing agents are added to jointly adjust the growth process of the silver powder so as to prepare the silver powder with high sphericity.
In patent application CN112404450A, a dispersant compounded by carboxymethyl cellulose V, carboxymethyl vitamin III and Arabic gum powder is added to adjust the viscosity of a reaction solution, so that the high sphericity silver powder is prepared. The silver powder prepared by the method has low sphericity, uneven particle size and lower tap density, and is not suitable for preparing solar cell silver paste with higher quality requirement.
Patent CN113600825B adds trisodium citrate into the oxidation solution and three dispersants of acacia, polyvinyl pyrrolidone and polyethylene glycol into the reducing agent solution to perform synergistic action, regulate and control the growth of silver powder, and prepare the silver powder with high sphericity. Although the sphericity of the silver powder prepared by the method is higher, the addition of excessive dispersant types has a competitive relationship while having a synergistic effect, so that more unformed fine silver powder exists in the silver powder, which reduces the fluidity and printing performance of the silver paste.
Therefore, the silver powder which is simple in material, high in sphericity and high in tap density is prepared, and the silver powder has important significance for the development of silver paste.
Disclosure of Invention
In order to prepare the silver powder with simple materials, high sphericity and high tap density, the application provides the preparation method of the silver powder with high sphericity.
The application provides a preparation method of high sphericity silver powder, which adopts the following technical scheme:
a preparation method of high sphericity silver powder comprises the following steps:
s1, mixing the following components in percentage by mass (30-100): (0.1-5) dissolving silver nitrate and crown ether in deionized water at 20-60 ℃ and uniformly mixing to form solution A;
s2, mixing the components in a mass ratio of (15-70): (5-25) stirring and dissolving the reducing agent and the dispersing agent in deionized water at the temperature of 20-60 ℃ to form a solution B;
s3, adjusting the pH value of the solution B to 3-9 by using a pH regulator, and adding the solution A to react under the condition of heating and stirring;
and S4, after the reaction technology, filtering the obtained silver powder slurry, washing the silver powder slurry by using deionized water and ethanol until the conductivity is less than or equal to 20 mu S/cm, and dispersing, filtering and drying the silver powder slurry to obtain the high-sphericity silver powder with the length-diameter ratio of 1.01-1.08.
By adopting the technical scheme, the coordination capability between the crown ether and the silver ions is adjusted by utilizing the principle that the cavity structure of the crown ether has selective action on ions and selecting the crown ethers with different sizes, so that the release rate of the silver ions is regulated and controlled, the oxidation-reduction reaction rate is finally controlled, and the purpose of preparing the silver powder with high sphericity is achieved.
Preferably, in S1, the crown ether is one of 12-crown-4, 15-crown-5, 18-crown-6, 21-crown-7 and 24-crown-8.
By adopting the technical scheme, the hole structures of 12-crown-4, 15-crown-5, 18-crown-6, 21-crown-7 and 24-crown-8 and the coordination capacity of silver ions are good, so that the release rate of the silver ions can be regulated and controlled, the redox reaction rate is controlled, and the sphericity of the silver powder is improved.
Preferably, in S2, the reducing agent is one or more of hydrogen peroxide, hydrazine hydrate, formaldehyde, acetaldehyde, hydroxylamine sulfate, ascorbic acid, glucose, ethylene glycol, and triethanolamine; further, ascorbic acid is preferable.
By adopting the technical scheme, the ascorbic acid is used as a reducing agent, and on one hand, silver ions attack oxygen atoms in the ascorbic acid, so that an oxidation-reduction reaction is generated; on the other hand, hydroxyl of the enol structure of the ascorbic acid can also be ionized to generate hydrogen ions, the hydrogen ions react with silver ions, finally, the ascorbic acid is oxidized into dehydroascorbic acid, and the silver ions are reduced into simple substance silver. After the silver ions contact and react with the ascorbic acid, the reduced silver is adsorbed around the dehydroascorbic acid, so that the agglomeration of silver particles can be reduced to a certain extent, the silver powder has a dispersing effect, and the tap density of the prepared silver powder is improved.
Preferably, in S2, the dispersant is one or more of cetyltrimethylammonium bromide, tween, gelatin, acacia, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, sodium citrate, triethanolamine, sodium dodecylbenzenesulfonate, and sodium dodecylsulfate; further, gelatin or polyethylene glycol is preferable.
By adopting the technical scheme, the gelatin is a macromolecular protein obtained by thermally denaturing collagen of animal connective tissues and breaking covalent bonds. Gelatin can not only pass through COO - With Ag + Electrostatic adsorption occurs, and more importantly, N derived from amino, imidazolyl and amido groups or S and Ag derived from methionine sulfoxide + Chemical bonding occurs. Therefore, the gelatin is mixed with the reducing agent and then mixed with the Ag + Reaction, ag can be avoided + The silver powder is subjected to electrostatic adsorption and chemical bonding with gelatin, so that the dispersion effect of the gelatin is reduced, the silver ions are seriously agglomerated, and the particle size of the obtained silver powder is increased; meanwhile, the gelatin is added later, so that the gelatin can hardly react with silver ions and can be immediately wrapped on new and large silver particles, and the dispersing effect is remarkable.
The polyethylene glycol contains two hydrophilic groups of hydroxyl and ether bond and has no hydrophobic group, the polyethylene glycol has excellent water solubility and stability, is not easily influenced by electrolyte, acid and alkali, is snakelike in aqueous solution, and is very easy to form strong hydrogen bonds with the surface of reduced metal simple substance particles, and the ether bond of the polyethylene glycol also has an affinity effect with the simple substance particles, so that the polyethylene glycol can be easily adsorbed on the surface of the particles to form a layer of polymer film for wrapping the metal simple substance particles, and the molecular bond layer of the polyethylene glycol stretches snakelike into the aqueous solution, so that the protective film wrapped on the surface of the particles has a certain thickness.
Preferably, in S3, the pH regulator is one or more of nitric acid, sulfuric acid, ammonia water, sodium hydroxide, sodium bicarbonate, and sodium carbonate.
By adopting the technical scheme, the pH value of the reaction system is adjusted, so that the prepared silver powder has high tap density. When the pH value of the reaction solution is lower, H in the system + More, be unfavorable for the reaction to go on to the reduction direction, reduced the supersaturation and the nucleation rate of silver in the solution, under lower supersaturation, silver crystal nucleus in case form, the silver that the reaction obtained just grows on original crystal nucleus, is favorable to the crystal nucleus to grow up, and the silver powder that obtains is just thick and the reunion is serious. When the pH value is higher, OH in the system - The method is more, which is not beneficial to the reaction going towards the oxidation direction, the nucleation rate is accelerated, a large number of generated small crystal nuclei are seriously agglomerated due to instability, and the dispersibility is poor.
Preferably, in the S4, the dosage of the dispersant used in the dispersion is 0.08-3.5% of the mass of the silver in the silver nitrate in the S1.
By adopting the technical scheme, the silver powder can be effectively further dispersed by using a proper amount of dispersing agent, the silver powder is prevented from agglomerating, the tap density of the silver powder is improved, the subsequent filtering efficiency of the silver powder is accelerated, and the preparation efficiency is improved.
Preferably, in S4, the dispersant is one or more of ricinoleic acid, caprylic acid, oleic acid, stearic acid, palmitic acid, lauric acid, myristic acid, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and oleylamine.
By adopting the technical scheme, the dispersing agent is added to carry out surface treatment on the silver powder, so that the silver powder can be prevented from agglomerating, and the tap density of the prepared silver powder is improved.
Preferably, in the S4, the drying temperature is 55-85 ℃ and the drying time is 6-15h.
By adopting the technical scheme, the obtained product is dried, so that the purity of the silver powder is higher, and meanwhile, the efficiency of preparing the silver powder is improved by optimizing the temperature and time during drying.
Preferably, in the S2, the stirring speed is 200-550rpm.
Preferably, in the S3, the rate of adding the solution A into the solution B is 100-200ml/min.
By adopting the technical scheme, the reaction can be accelerated by increasing the stirring speed, and the granularity of the silver powder prepared by the reaction is obviously reduced; the stirring speed is too low, the reaction speed is slow, and the granularity of the prepared silver powder is larger.
When the addition rate of the solution A is too high, a large amount of oxidant is added in a short time, the reaction speed is too high, the silver crystal nucleus grows rapidly in the reducing atmosphere after being generated, and the particle size of the generated silver powder is larger; when the addition rate of the solution A is too low, the reaction speed is reduced, the reducing agent is consumed after the silver crystal nucleus is generated, the crystal nucleus is dispersed into the whole solution before growing up, and the possibility of growing up the crystal nucleus is reduced.
In summary, the present application includes at least one of the following beneficial technical effects:
1. according to the method, a small amount of crown ether which is a macromolecular cyclic substance is added into the oxidizing solution, and the different coordination abilities between crown ethers with different sizes and silver ions are utilized, so that the release rate of the silver ions can be regulated and controlled, the reaction rate of oxidation reduction is influenced, and the silver powder with high sphericity is finally prepared;
2. according to the method, various dispersing agents are not used, the materials are simple, the prepared silver powder is high in sphericity and uniform in size, has no unformed fine silver powder, is high in tap density, and is very suitable for preparing the solar cell positive silver paste with good fluidity and high printing performance;
3. the preparation method is simple, the preparation of the high-sphericity silver powder can be realized through simple raw materials and equipment, the preparation method is suitable for large-scale industrial production, and the usability is good.
Drawings
FIG. 1 is an SEM image of a silver powder prepared in example 15 of the present application.
FIG. 2 is a schematic diagram showing the aspect ratio of silver powder prepared in example 15 of the present application.
FIG. 3 is an SEM image of a silver powder prepared in comparative example 1 of the present application.
Detailed Description
The present application is described in further detail below by way of examples and figures 1-3.
All the starting materials in the examples are commercially available.
Example 1
The embodiment discloses a preparation method of high-sphericity silver powder, which comprises the following steps:
s1, dissolving 30g of silver nitrate and 0.1g12-crown-4 in 1L of deionized water at the temperature of 20 ℃, and uniformly mixing to form a solution A;
s2, dissolving 30g of ascorbic acid and 10g of gelatin in 2L of deionized water at the temperature of 20 ℃, completely dissolving at the stirring speed of 200rpm, and uniformly mixing to form a solution B;
s3, adjusting the pH value of the solution B to 9 by using ammonia water, adding the solution A into the solution B at a speed of 100ml/min under the condition of keeping the temperature and the stirring speed of the solution B unchanged, and reacting for 30min;
and S4, after the reaction is finished, filtering the obtained silver powder slurry, respectively washing the silver powder slurry by deionized water and ethanol until the conductivity of the wastewater is less than or equal to 20 mu S/cm, adding 0.381g of oleic acid into the dispersion formed by dissolving the oleic acid in 1L of ethanol, dispersing the mixture at a high speed of 1800rpm, filtering the mixture, and drying the mixture at the temperature of 55 ℃ for 15 hours.
Example 2
This example is substantially the same as example 1 except that in S1, 48g of silver nitrate and 0.2g12-crown-4 were dissolved in 1L of deionized water at a temperature of 20 ℃ and mixed uniformly to form a solution a.
Example 3
This example is essentially the same as example 1 except that in S1, 50g of silver nitrate and 0.25g of 12-crown-4 were dissolved in 0.5L of deionized water at a temperature of 20 ℃ and mixed well to form solution A.
Example 4
This example is essentially the same as example 3 except that in S1, 48g of silver nitrate and 0.2g15-crown-5 were dissolved in 1L of deionized water at 20 ℃ and mixed well to form solution A.
Example 5
This example is essentially the same as example 3 except that in S1, 48g of silver nitrate and 0.2g18-crown-6 were dissolved in 1L of deionized water at 20 ℃ and mixed well to form solution A.
Example 6
This example is essentially the same as example 3, except that in S1, 48g of silver nitrate and 0.2g21-crown-7 were dissolved in 1L of deionized water at a temperature of 20 ℃ and mixed well to form solution A.
Example 7
This example is essentially the same as example 3 except that in S1, 48g of silver nitrate and 0.2g24-crown-8 were dissolved in 1L of deionized water at 20 ℃ and mixed well to form solution A.
Example 8
This example is substantially the same as example 5 except that in S2, 25g of ascorbic acid and 10g of gelatin were dissolved in 1L of deionized water at a temperature of 20 ℃, completely dissolved with a stirring speed of 200rpm, and mixed uniformly to form a solution B.
Example 9
This example is substantially the same as example 5 except that, in S2, 70g of ascorbic acid and 25g of gelatin were dissolved in 1L of deionized water at a temperature of 20 ℃, completely dissolved with stirring at 200rpm, and mixed uniformly to form a B solution.
Example 10
This example is substantially the same as example 8 except that in S2, 25g of ascorbic acid and 10g of polyethylene glycol were dissolved in 1L of deionized water at a temperature of 20 ℃, completely dissolved with a stirring speed of 200rpm, and mixed uniformly to form a solution B.
Example 11
This example is substantially the same as example 8 except that, in S3, the solution B was adjusted to pH 7 with sodium bicarbonate, and the solution a was added to the solution B at a rate of 100ml/min while maintaining the temperature and stirring speed of the solution B, and reacted for 30min; sodium bicarbonate may also be replaced with sodium hydroxide or sodium carbonate in other embodiments;
example 12
This example is substantially the same as example 8 except that in S3, the solution B was adjusted to pH 3 with nitric acid, and the solution a was added to the solution B at a rate of 100ml/min while maintaining the temperature and stirring speed of the solution B, and reacted for 30min; nitric acid may also be replaced with sulfuric acid in other embodiments;
example 13
The present example is substantially the same as example 11, except that, in S4, after the reaction is completed, the obtained silver paste is filtered, washed with deionized water and ethanol respectively until the conductivity of the wastewater is less than or equal to 20 μ S/cm, and added with 0.610g of oleic acid to be dissolved in 1L of ethanol to form a dispersion, and the dispersion is dispersed at a high speed of 1800rpm, filtered, and dried at a temperature of 80 ℃ for 8 hours.
Example 14
The present example is substantially the same as example 11, except that, in S4, after the reaction is completed, the obtained silver paste is filtered, washed with deionized water and ethanol respectively until the conductivity of the wastewater is less than or equal to 20 μ S/cm, and added with 1.07g of oleic acid to be dissolved in 1L of ethanol to form a dispersion, and the dispersion is dispersed at a high speed of 1800rpm, filtered, and dried at a temperature of 80 ℃ for 8 hours. In other embodiments, oleic acid may also be replaced with one or more of ricinoleic acid, caprylic acid, stearic acid, palmitic acid, lauric acid, myristic acid, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, oleylamine.
Example 15
This example is essentially the same as example 13 except that, S1, 48g of silver nitrate and 0.2g18-crown-6 were dissolved in 1L of deionized water at 40 ℃ and mixed well to form solution A; s2, dissolving 25g of ascorbic acid and 10g of gelatin in 1L of deionized water at the temperature of 40 ℃, completely dissolving at the stirring speed of 350rpm, and uniformly mixing to form a solution B; s3, adjusting the pH value of the solution B to 9 by using ammonia water, adding the solution A into the solution B at a speed of 100ml/min under the condition of keeping the temperature and the stirring speed of the solution B unchanged, and reacting for 30min; and S4, after the reaction is finished, filtering the obtained silver powder slurry, respectively washing the silver powder slurry by deionized water and ethanol until the conductivity of the wastewater is less than or equal to 20 mu S/cm, adding 0.610g of oleic acid into the dispersion formed by dissolving the oleic acid in 1L of ethanol, dispersing the mixture at a high speed of 1800rpm, filtering the mixture, and drying the mixture at a temperature of 80 ℃ for 8 hours.
Example 16
This example is essentially the same as example 11 except that, S1, 48g of silver nitrate and 0.2g18-crown-6 were dissolved in 1L of deionized water at 60 ℃ and mixed well to form solution A; s2, dissolving 25g of ascorbic acid and 10g of gelatin in 1L of deionized water at the temperature of 60 ℃, completely dissolving at the stirring speed of 550rpm, and uniformly mixing to form a solution B; s3, adjusting the pH value of the solution B to 9 by using ammonia water, adding the solution A into the solution B at a speed of 200ml/min under the condition of keeping the temperature and the stirring speed of the solution B unchanged, and reacting for 30min; and S4, after the reaction is finished, filtering the obtained silver powder slurry, respectively washing the silver powder slurry by deionized water and ethanol until the conductivity of the wastewater is less than or equal to 20 mu S/cm, adding 0.610g of oleic acid into a dispersion liquid formed by dissolving the oleic acid in 1L of ethanol, dispersing the mixture at a high speed of 1800rpm, filtering the mixture, and drying the mixture at a temperature of 85 ℃ for 6 hours.
Comparative example
Comparative example 1
This comparative example is different from example 15 in that the amount of 18-crown-6 added in S1 is 0, and the other steps are the same as example 15.
Comparative example 2
The difference between the comparative example and the example 1 is that in S1, 10g of silver nitrate and 1g of 12-crown-4 are dissolved in 1L of deionized water at the temperature of 20 ℃ and are uniformly mixed to form a solution A; the rest of the procedure was the same as in example 1.
Comparative example 3
The difference between the comparative example and the example 1 is that in S1, 40g of silver nitrate and 0.01g of 12-crown-4 are dissolved in 0.2L of deionized water at the temperature of 20 ℃ and are uniformly mixed to form a solution A; the rest of the procedure was the same as in example 1.
Comparative example 4
This comparative example is different from example 15 in that in S4, a dispersion of oleic acid was not added, and the procedure was the same as in example 15.
Performance detection
1. Degree of sphericity
The silver powders in the examples and comparative examples were examined by a scanning electron microscope, and the sphericity of the silver powders was judged by the aspect ratio of the silver powders.
2. Particle size detection
The silver powders of the examples and comparative examples were examined by a Malvern laser particle sizer, and diameters corresponding to 10%, 50%, 90%, and 100% of the cumulative particle size distribution of the silver powders were measured and designated as D (0.1), D (0.5), D (0.9), and D (1.0), respectively.
3. Tap density detection
The silver powders in the examples and comparative examples were examined by a tap density tester to measure tap densities of the silver powders.
TABLE 1 Table of data for testing the properties of examples 1 to 16 and comparative examples 1 to 4
Referring to table 1, in combination with examples 1 to 3 and comparative examples 2 and 3, it can be seen that the silver powders obtained by varying the mass ratio of silver nitrate to crown ether within an appropriate range all have a higher sphericity; however, when the mass ratio of silver nitrate to crown ether was too small (comparative example 2) or too large (comparative example 3), the sphericity of the silver powder obtained was decreased. This is because too large or too small a mass ratio of silver nitrate to crown ether affects the degree of matching between crown ether and silver ions, thereby reducing the sphericity of the silver powder.
Referring to table 1, in combination with examples 2 and 4 to 7, it can be seen that the silver powders prepared by changing the kinds of crown ethers were found to have higher sphericities and tap densities; particularly, the sphericity of the silver powder prepared by the 18-crown-6 is the highest, because the diameter of the 18-crown-6 is 260-320pm, and the diameter of the silver ions is 252pm, the matching degree of the two is higher, and the binding force is strongest, so the 18-crown-6 can slowly release the silver ions during the reaction, and further improve the sphericity of the prepared silver powder.
Referring to table 1, in combination with examples 5, 8 and 9, it can be seen that the silver powders obtained by varying the mass ratio of the reducing agent to the dispersing agent within an appropriate range all have higher sphericity and tap density, and particularly when the mass ratio of ascorbic acid to gelatin is 5, the sphericity and tap density of the prepared silver powder are the highest. The surface resistance effect can be exerted by covering a proper amount of the dispersing agent on the silver particles; excessive dispersing agent can make the reaction solution sticky, so that the contact area of the reducing agent and the silver nitrate is reduced, the reaction rate is slowed down, and meanwhile, the generated simple substance silver is also slowed down because the film formed by the dispersing agent is thick, so that two processes of particle nucleation and growth cannot be effectively separated, the granularity of the obtained silver powder is large, and the later washing and filtering are not facilitated when the using amount of the dispersing agent is excessive.
Referring to table 1, in combination with examples 8 and 10, it can be seen that the silver powders obtained when the dispersant gelatin in step 2 was replaced with polyethylene glycol all had higher sphericity and tap density.
Referring to Table 1 in combination with examples 8, 11 and 12, it can be seen that the silver powders obtained by varying the pH in step 3 within an appropriate range all have higher tap densities, and particularly, the tap density of the silver powder obtained is the highest when the pH is 7. When the pH value is lower, H in the system + More silver is not beneficial to the reaction in the reduction direction, the supersaturation degree and nucleation rate of silver in the solution are reduced, and once a silver crystal nucleus is formed under the lower supersaturation degree, the silver obtained by the reaction grows on the original crystal nucleus, so that the crystal nucleus is beneficial to growth, the obtained silver powder is coarse and serious in agglomeration, and the tap density is reduced; when the pH value is higher, OH in the system - The method has the advantages of being large in number, not beneficial to the reaction towards the oxidation direction, high in nucleation speed, poor in dispersity and reduced in tap density, and a large number of generated small crystal nuclei are seriously agglomerated due to instability.
Referring to table 1, in combination with examples 11, 13 and 14 and comparative example 4, it can be seen that the tap density of the silver powder can be increased by adding oleic acid (dispersant) to form a dispersion in the step S4. Particularly, when the amount of oleic acid is 2% by mass of silver in silver nitrate, the tap density is the highest. The silver particles are covered by a proper amount of oleic acid, so that the silver powder can be prevented from agglomerating, the tap density of the silver powder is improved, the subsequent filtering efficiency of the silver powder is accelerated, and the preparation efficiency is improved.
Referring to Table 1, in combination with examples 13, 15 and 16, it can be seen that silver powders having different particle diameters, but having higher sphericity, can be prepared by varying the reaction temperature of the solution in each preparation step, the stirring speed, the rate of addition of the solution A to the solution B, and the temperature and time at the time of drying within appropriate ranges.
Referring to Table 1 in conjunction with FIGS. 1 to 3, it can be seen by comparing example 15 with comparative example 1 that the silver powder prepared using 18-crown-6 has high sphericity and high tap density compared to the silver powder prepared without adding crown ether. As the macrocyclic ligands of the crown ethers have certain cavity structures, the crown ethers and the silver ions have good matching degree for the given crown ethers and the silver ions, the silver ions can enter the cavity holes of the crown ethers, the coordination oxygen atoms of the ligands and the silver ions have strong interaction and generate electrostatic attraction, the release speed of the silver ions is slow and controllable, and the sphericity of the prepared silver powder is improved by controlling the redox reaction rate.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (10)
1. A preparation method of high sphericity silver powder is characterized by comprising the following steps: the method comprises the following steps:
s1, mixing the following components in percentage by mass (30-100): (0.1-5) dissolving silver nitrate and crown ether in deionized water at 20-60 ℃ and uniformly mixing to form solution A;
s2, mixing the components in a mass ratio of (15-70): (5-25) stirring and dissolving the reducing agent and the dispersing agent in deionized water at the temperature of 20-60 ℃ to form a solution B;
s3, adjusting the pH value of the solution B to 3-9 by using a pH regulator, and adding the solution A to react under the condition of heating and stirring;
and S4, after the reaction is finished, filtering the obtained silver slurry, washing the silver slurry with deionized water and ethanol until the conductivity is less than or equal to 20 mu S/cm, and dispersing, filtering and drying the silver slurry to obtain the high-sphericity silver powder with the length-diameter ratio of 1.01-1.08.
2. The method for preparing silver powder with high sphericity according to claim 1, wherein: in the S1, the crown ether is one of 12-crown-4, 15-crown-5, 18-crown-6, 21-crown-7 and 24-crown-8.
3. The method for preparing silver powder with high sphericity according to claim 1, wherein: in the S2, the reducing agent is one or more of hydrogen peroxide, hydrazine hydrate, formaldehyde, acetaldehyde, hydroxylamine sulfate, ascorbic acid, glucose, ethylene glycol and triethanolamine.
4. The method for preparing a silver powder with high sphericity according to claim 1, wherein: in the S2, the dispersant is one or more of hexadecyl trimethyl ammonium bromide, tween, gelatin, arabic gum, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, sodium citrate, triethanolamine, sodium dodecyl benzene sulfonate and sodium dodecyl sulfate.
5. The method for preparing a silver powder with high sphericity according to claim 1, wherein: in S3, the pH regulator is one or more of nitric acid, sulfuric acid, ammonia water, sodium hydroxide, sodium bicarbonate and sodium carbonate.
6. The method for preparing a silver powder with high sphericity according to claim 1, wherein: in the S4, the dosage of the dispersant used in the dispersion is 0.08-3.5% of the mass of the silver in the silver nitrate in the S1.
7. The method for preparing silver powder with high sphericity according to claim 6, wherein: in S4, the dispersing agent is one or more of ricinoleic acid, caprylic acid, oleic acid, stearic acid, palmitic acid, lauric acid, myristic acid, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and oleylamine.
8. The method for preparing a silver powder with high sphericity according to claim 1, wherein: in the S4, the drying temperature is 55-85 ℃, and the drying time is 6-15h.
9. The method for preparing a silver powder with high sphericity according to claim 1, wherein: in the S2, the stirring speed is 200-550rpm.
10. The method for preparing silver powder with high sphericity according to claim 1, wherein: in the S3, the rate of adding the solution A into the solution B is 100-200ml/min.
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| CN116422896A (en) * | 2023-04-25 | 2023-07-14 | 深圳市哈深智材科技有限公司 | Conductive silver paste, silver powder and method for preparing silver powder by utilizing ionic dispersing agent |
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| CN114131038A (en) * | 2021-12-15 | 2022-03-04 | 苏州银瑞光电材料科技有限公司 | Preparation method of silver powder with high tap density |
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| CN116422896A (en) * | 2023-04-25 | 2023-07-14 | 深圳市哈深智材科技有限公司 | Conductive silver paste, silver powder and method for preparing silver powder by utilizing ionic dispersing agent |
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