CN112570728B - Flake silver powder and preparation method and application thereof - Google Patents
Flake silver powder and preparation method and application thereof Download PDFInfo
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- CN112570728B CN112570728B CN202011436036.6A CN202011436036A CN112570728B CN 112570728 B CN112570728 B CN 112570728B CN 202011436036 A CN202011436036 A CN 202011436036A CN 112570728 B CN112570728 B CN 112570728B
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 115
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 238000003756 stirring Methods 0.000 claims abstract description 42
- 229910052709 silver Inorganic materials 0.000 claims abstract description 39
- 239000004332 silver Substances 0.000 claims abstract description 39
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 38
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 claims abstract description 37
- 238000006243 chemical reaction Methods 0.000 claims abstract description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000008367 deionised water Substances 0.000 claims abstract description 30
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 30
- 238000000034 method Methods 0.000 claims abstract description 26
- 239000002270 dispersing agent Substances 0.000 claims abstract description 24
- 239000007788 liquid Substances 0.000 claims abstract description 16
- 238000002156 mixing Methods 0.000 claims abstract description 16
- 239000012295 chemical reaction liquid Substances 0.000 claims abstract description 15
- 238000000926 separation method Methods 0.000 claims abstract description 15
- 238000001035 drying Methods 0.000 claims abstract description 12
- 239000002245 particle Substances 0.000 claims abstract description 11
- 230000001105 regulatory effect Effects 0.000 claims abstract description 11
- -1 silver ions Chemical class 0.000 claims abstract description 11
- 238000005406 washing Methods 0.000 claims abstract description 9
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 62
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 32
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 31
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 24
- 239000011668 ascorbic acid Substances 0.000 claims description 16
- 229960005070 ascorbic acid Drugs 0.000 claims description 16
- 235000010323 ascorbic acid Nutrition 0.000 claims description 16
- 239000000843 powder Substances 0.000 claims description 13
- 239000001856 Ethyl cellulose Substances 0.000 claims description 12
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 claims description 12
- 229920001249 ethyl cellulose Polymers 0.000 claims description 12
- 235000019325 ethyl cellulose Nutrition 0.000 claims description 12
- 239000012535 impurity Substances 0.000 claims description 10
- 230000002572 peristaltic effect Effects 0.000 claims description 10
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 9
- 239000011521 glass Substances 0.000 claims description 9
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 8
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 8
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 8
- 238000004140 cleaning Methods 0.000 claims description 8
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 8
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 8
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 8
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
- XNGYKPINNDWGGF-UHFFFAOYSA-L silver oxalate Chemical compound [Ag+].[Ag+].[O-]C(=O)C([O-])=O XNGYKPINNDWGGF-UHFFFAOYSA-L 0.000 claims description 5
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 4
- 239000008103 glucose Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000003960 organic solvent Substances 0.000 claims description 3
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 claims description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 2
- 238000009826 distribution Methods 0.000 claims description 2
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 238000005096 rolling process Methods 0.000 claims description 2
- 239000001509 sodium citrate Substances 0.000 claims description 2
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 230000000052 comparative effect Effects 0.000 description 5
- 238000006722 reduction reaction Methods 0.000 description 5
- 238000000498 ball milling Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 239000008204 material by function Substances 0.000 description 2
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- PLKATZNSTYDYJW-UHFFFAOYSA-N azane silver Chemical compound N.[Ag] PLKATZNSTYDYJW-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003670 easy-to-clean Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000002003 electrode paste Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000010297 mechanical methods and process Methods 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000000967 suction filtration Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
Classifications
-
- 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
-
- 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
- B22F1/06—Metallic powder characterised by the shape of the particles
- B22F1/068—Flake-like particles
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
-
- 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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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Dispersion Chemistry (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
Abstract
The invention relates to flake silver powder, and a preparation method and application thereof, and the preparation method comprises the following steps: s1, dissolving a silver source in deionized water to prepare a silver ion-containing solution, and dissolving a reducing agent in the deionized water to obtain a reducing agent solution, wherein the concentration range of silver ions in the silver ion-containing solution is 0.1-2mol/L; s2, preparing pH regulating solution, adding the pH regulating solution into silver ion-containing solution, and regulating the pH value of the solution to 8-12; s3, adding the dispersing agent into the silver ion-containing solution, and uniformly stirring; and S4, fully mixing and reducing the silver ion-containing solution and the reducing agent solution in the stirring process at the temperature of 20-60 ℃ to obtain silver particles, adding part of the reducing agent solution into part of the silver ion-containing solution in the mixing process, fully reducing and stirring, simultaneously adding the rest of the reducing agent solution and the silver ion solution into the system, continuously stirring and reducing until the reaction is finished, carrying out solid-liquid separation on the reaction liquid, and washing and drying to obtain the flaky silver powder. The method regulates and controls the particle size and the sheet diameter of the silver powder, is easy to operate, and can meet different use requirements.
Description
Technical Field
The invention relates to conductive metal powder and a preparation method thereof, in particular to flake silver powder and a preparation method and application thereof.
Background
Silver powder is used as a main constituent of the conductive silver paste, and plays a role of a functional phase in the silver paste. The shape, dispersibility, grain size and other parameters of the silver powder directly relate to the mechanical, electrical and printing properties of the conductive paste, so that the conductivity of electronic components is affected, and the quality of the silver powder determines whether the conductive paste can meet the requirements of the performance of electronic products.
Currently, silver powder used for the preparation of conductive paste is mainly spherical silver powder and plate-shaped silver powder. Among them, the silver flake powder is an important component of the electrode paste of the surface mount device. The contact between particles of the flake silver powder is surface contact or line contact, so that the contact surface is larger than the contact surface of point contact of spherical silver powder, the resistance is relatively lower, and the conductivity is better; meanwhile, compared with silver powder with other morphologies, the coating area of the flake silver powder with the same quality is larger, and the use amount of the silver powder can be saved by adopting the flake silver powder, and meanwhile, the thickness of the coating is reduced, so that the miniaturization of electronic components is facilitated. At present, the spherical silver powder is prepared by a chemical reduction method firstly, and then is pressed into flakes by a mechanical ball milling method to obtain flake silver powder, but the variable factors are more in the ball milling process, different batches are difficult to control, and impurities are easy to introduce in the ball milling process.
The Chinese patent application No. 201911250739.7 discloses a preparation method of flake nano silver powder, which comprises the steps of adding a dispersing agent into a reducing agent solution, mixing with a silver-ammonia solution, heating and reacting to prepare the nano silver powder. However, in practical application, the preparation of the conductive silver paste is mainly performed by using micron silver powder, and the micron silver powder can ensure the dispersibility in a carrier while ensuring the conductivity of the paste. In addition, the Chinese patent with the application number of 201711060549.X discloses a method for preparing nano-scale flake silver powder by a chemical method, but the seed crystal is prepared by silver nitrate alone in the operation, the operation is complicated, three surfactants are added to increase the subsequent cleaning difficulty, the variety of surface residual substances is increased, and the product use is easily influenced. Therefore, a new preparation method of the flake silver powder is needed to be provided, and the method is more suitable for producing the flake silver powder for large-scale application.
Disclosure of Invention
In order to make up the defects in the prior art, the invention provides the flake silver powder, the preparation method and the application thereof, the silver powder is prepared by adopting a chemical reduction method, a product can be directly obtained in one step, the preparation process is simplified, meanwhile, the problems existing in the preparation by a mechanical method can be avoided, the morphology of the obtained silver powder is flake, the reproducibility of the silver powder preparation is good, substances added in the preparation process are easy to clean and remove, and the silver powder can be correspondingly used in the field of electronic functional materials as a conductive paste function.
The preparation method of the flake silver powder comprises the following steps:
s1, dissolving a silver source in deionized water to prepare a silver ion-containing solution, and dissolving a reducing agent in the deionized water to obtain a reducing agent solution, wherein the concentration range of silver ions in the silver ion-containing solution is 0.1-2mol/L;
s2, preparing pH regulating solution, adding the pH regulating solution into silver ion-containing solution, and regulating the pH value of the solution to 8-12;
s3, adding the dispersing agent into the silver ion-containing solution, and uniformly stirring;
and S4, fully mixing and reducing the silver ion-containing solution and the reducing agent solution in the stirring process at the temperature of 20-60 ℃ to obtain silver particles, adding part of the reducing agent solution into part of the silver ion-containing solution in the mixing process, fully reducing and stirring, simultaneously adding the rest of the reducing agent solution and the silver ion solution into the system, continuously stirring and reducing until the reaction is finished, carrying out solid-liquid separation on the reaction liquid, and washing and drying to obtain the flaky silver powder.
Preferably, in the step S1, the concentration of the silver ions ranges from 0.1 to 0.5mol/L.
Further, in step S1, the silver source is one or two of silver nitrate and silver oxalate. Silver nitrate is preferred as the silver source.
Further, in step S1, the reducing agent includes one of ascorbic acid, glucose, hydrazine hydrate or hydrogen peroxide, and water is used as a solvent, and the amount of the reducing agent added is 1-2 times of the amount of the silver ions added.
Preferably, the reducing agent is ascorbic acid, which is added in an amount of 1.1 to 1.3 times.
Further, in step S2, the pH adjusting solution is an alkaline adjusting agent, and the alkaline adjusting agent is one or a mixture of ammonia water, sodium hydroxide and potassium hydroxide.
Preferably, in the step S2, the pH value is 8-10, and the alkaline regulator is ammonia water.
Specifically, the specific step of pH adjustment is to dropwise add an alkaline regulator to the prepared silver ion-containing solution to adjust the pH value, and the amount of the alkaline regulator added and the adjustment end point are determined by metering by using a pH meter monitoring system.
Still further, the dispersing agent in the step S3 includes any one of citric acid, sodium citrate, polyvinylpyrrolidone, polymethacrylamide and ethylcellulose, and the dispersing agent is 1wt% to 30wt% of the silver source.
Specifically, the dispersant is in the form of powder.
Preferably, the dispersing agent is one of polyvinylpyrrolidone or ethylcellulose, and the content of the dispersing agent is 10wt% to 20wt% of the silver source.
Preferably, the dispersant is polyvinylpyrrolidone; after the reaction is finished, the solid-liquid separation of the reaction liquid is carried out, deionized water is firstly used for cleaning 3 to 5 times, and ethanol is then used for cleaning 1 time to remove surface impurities.
Further preferably, the dispersing agent is ethyl cellulose, and the ethyl cellulose is added into the silver ion solution after being dissolved by an organic solvent; after the reaction is finished, the solid-liquid separation of the reaction liquid is carried out, and deionized water is used for cleaning for 1 time to remove surface impurities.
Specifically, the organic solvent is one of methanol or ethanol, preferably ethanol.
Further, in step S4, the ratio of the reducing agent solution to the silver ion-containing solution is 20% -80% for the first time, after the reducing agent solution and the silver ion-containing solution are fully reduced and stirred for a period of time, the rest reducing agent solution and the silver ion-containing solution are simultaneously added into the system after the reaction is completed through a peristaltic pump to be reduced to obtain silver particles, and the sample adding rate of the peristaltic pump is kept consistent.
Further, the stirring mode is mechanical stirring, and the speed is 800-1200r/min.
Preferably, the addition time is 1-2min, and the reaction temperature is controlled at 25-35 ℃.
Specifically, after solid-liquid separation of silver particles obtained after the reaction is finished, washing with deionized water and ethanol to remove surface impurities, and drying in an oven to obtain the micron-sized flake silver powder.
Further specifically, the solid-liquid separation mode is suction filtration, and the drying temperature in the oven is 75-85 ℃ and the drying time is 2-3 hours.
The flake silver powder is prepared according to the method, wherein the flake diameter distribution of the silver powder is 1.0-5.0 mu m, and the flake thickness is less than 200nm.
The conductive paste is prepared from silver powder, wherein the square resistance range of the conductive paste is 6-10mΩ/≡, the conductive paste comprises 75-85% of silver powder, 3-7% of glass powder and 12-18% of organic carrier, and the conductive paste is prepared by uniformly mixing and then passing through a rolling mill.
Preferably, the conductive paste comprises 80% of silver powder, 5% of glass frit and 15% of organic carrier.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the prior art that a large number of mechanical ball milling methods are used in industrial production, the preparation process is simplified, the requirements on experimental equipment are low, the particle size and the sheet diameter of the silver powder can be regulated and controlled by adjusting the relative conditions such as concentration, dispersant content, reaction temperature and the like, the operation is easy, and different use requirements can be met.
2. According to the invention, a mode of multiple sample adding is adopted, a part of reducing agent solution is added into a part of silver ion solution for reduction reaction to prepare the seed crystal, and then the rest solution is added into a reaction system, so that the preparation flow of the seed crystal is simplified, the growth of silver powder can be better controlled by utilizing the seed crystal method principle, the particle size and the sheet diameter of the sheet silver powder are controlled, and the uniformity of silver powder preparation is improved.
3. The method has the advantages that various substances added into the system are low in toxicity and pollution, the reaction is easy to remove after the reaction is finished, the process flow is simple, the reaction rate can be controlled by adjusting the pH value of the silver ion-containing solution, so that the pH value of a final system is determined, the production condition is better determined, the silver powder can generate a better flaky structure, meanwhile, the experimental investigation is convenient, the concentration of the silver nitrate and the reducing agent of the system at all moments in a symmetrical liquid adding mode is similar, and the particles of the final product are more uniform, so that the method is suitable for large-scale industrial production.
4. The dispersing agent ethyl cellulose used in the reaction can be used as a thickening agent for preparing an organic carrier in the conductive slurry, so that the conductive slurry is cleaned for 1 time later, the cleaning process is effectively reduced, the operation flow for preparing silver powder is further simplified, and part of residual dispersing agent does not influence the subsequent use.
5. The prepared silver powder has a better micron-sized sheet structure, and can be widely applied to the fields of conductive slurry, photosensitive materials, electrode materials, decorative materials, silver alloy welding materials, composite materials, energy fields, silver-series antibacterial materials, silver catalytic industry and the like; in particular to further preparing conductive paste which can be used as the conductive paste to be correspondingly used in the field of electronic functional materials.
Drawings
FIG. 1 is a scanning electron microscope picture of the plate-like silver powder obtained in example 1;
FIG. 2 is a scanning electron microscope picture of the plate-like silver powder obtained in example 2;
FIG. 3 is a scanning electron microscope picture of the plate-like silver powder obtained in example 3;
FIG. 4 is a scanning electron microscope picture of the silver powder obtained in comparative example 1.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.
Example 1
Adding 10g of silver nitrate into 250g of deionized water, fully stirring and dissolving, and adding 1g of polyvinylpyrrolidone into the silver nitrate solution; dissolving 6.5g of ascorbic acid in 250g of deionized water to prepare a reducing agent solution; adding an ammonia water solution into the silver nitrate solution to adjust the pH value to 10, and stirring to clarify the solution, wherein the concentration of silver ions in the silver ion-containing solution is 0.24mol/L, and the dispersing agent is 10wt% of the silver source; adding 20% of ascorbic acid solution into 20% of silver nitrate solution, fully stirring and reducing, adding the rest silver nitrate solution and the ascorbic acid solution into the reaction solution by using a peristaltic pump after 20min, continuously stirring and reducing, wherein the stirring speed is 1000r/min, and the reaction temperature is controlled at 20 ℃.
After the reaction is completed, the solid-liquid separation of the reaction liquid is carried out, the reaction liquid is washed 3 times by deionized water and then is washed 1 time by ethanol, and the silver powder is obtained by drying in an oven at 80 ℃ for 2 hours, and a scanning electron microscope picture is shown in figure 1.
Mixing the silver powder with 80% of silver powder, 5% of glass powder and 15% of organic carrier according to a proportion, stirring uniformly, obtaining conductive paste (silver paste) through a three-roller mill, and sintering after screen printing to obtain the conductive circuit, wherein the square resistance range is 6.8mΩ/≡.
Example 2
10g of silver nitrate is dissolved in 250g of deionized water, and 1.5g of polyvinylpyrrolidone is added into the silver nitrate solution; dissolving 6.5g of ascorbic acid in 250g of deionized water to prepare a reducing agent solution; adding an ammonia water solution into the silver nitrate solution to adjust the pH value to 10, and stirring to clarify the solution, wherein the concentration of silver ions in the silver ion-containing solution is 0.24mol/L, and the dispersing agent is 15wt% of the silver source; adding 20% of ascorbic acid solution into 20% of silver nitrate solution, fully stirring and reducing, adding the rest silver nitrate solution and the ascorbic acid solution into the reaction solution by using a peristaltic pump after 20min, continuously stirring and reducing, wherein the stirring speed is 1000r/min, and the reaction temperature is controlled at 25 ℃.
After the reaction is completed, the solid-liquid separation of the reaction liquid is carried out, the reaction liquid is washed 3 times by deionized water and then is washed 1 time by ethanol, and the silver powder is obtained by drying in an oven at 80 ℃ for 2 hours, and a scanning electron microscope picture is shown in figure 2.
Mixing the silver powder with 84% of silver powder, 4% of glass powder and 12% of organic carrier according to a proportion, stirring uniformly, and then obtaining the conductive paste (silver paste) through a three-roller mill, wherein the square resistance range is 7.5mΩ/≡.
Example 3
Dissolving 10g of silver nitrate in 250g of deionized water, fully dissolving 1.5g of ethyl cellulose in 20ml of ethanol, adding the ethyl cellulose solution into the silver nitrate solution, and fully and uniformly mixing; dissolving 6.5g of ascorbic acid in 250g of deionized water to prepare a reducing agent solution; adding an ammonia water solution into the silver nitrate solution to adjust the pH value to 9, and stirring to clarify the solution, wherein the concentration of silver ions in the silver ion-containing solution is 0.24mol/L, and the dispersing agent is 15wt% of the silver source; adding 40% of ascorbic acid solution into 40% of silver nitrate solution, fully stirring and reducing, adding the rest silver nitrate solution and the ascorbic acid solution into the reaction solution by using a peristaltic pump after 20min, continuously stirring and reducing, wherein the stirring speed is 900r/min, and the reaction temperature is controlled at 35 ℃.
After the reaction is completed, the solid-liquid separation of the reaction liquid is carried out, the surface impurities are removed by washing with deionized water for 1 time, the silver powder is obtained by drying in an oven at 80 ℃ for 2 hours, and a scanning electron microscope picture is shown in figure 3.
Mixing the silver powder with 77% of silver powder, 6% of glass powder and 17% of organic carrier according to a proportion, stirring uniformly, and then obtaining the conductive paste (silver paste) through a three-roller mill, wherein the square resistance range is 7.1mΩ/≡.
Example 4
Dissolving 35g of silver nitrate in 250g of deionized water, fully dissolving 4.5g of ethyl cellulose in 20ml of ethanol, adding an ethyl cellulose solution into the silver nitrate solution, and fully and uniformly mixing; 23g of glucose is dissolved in 250g of deionized water to prepare a reducing agent solution; adding an ammonia water solution into the silver nitrate solution to adjust the pH value to 8, and stirring to clarify the solution, wherein the concentration of silver ions in the silver ion-containing solution is 0.83mol/L, and the dispersing agent is 12.8wt% of a silver source; adding 65% glucose solution into 65% silver nitrate solution, stirring thoroughly for reduction, adding the rest silver nitrate solution and ascorbic acid solution into the reaction solution by using peristaltic pump after 25min, continuing stirring for reduction, stirring at 1100r/min, and controlling the reaction temperature at 20 ℃.
After the reaction is finished, the solid-liquid separation of the reaction liquid is carried out, deionized water is used for washing for 1 time to remove surface impurities, and an oven is dried at 80 ℃ for 2 hours to obtain silver powder, so that the silver powder is better dried, and ethanol can be used for washing once again after the silver powder is washed by the deionized water.
Mixing the silver powder with glass powder and an organic carrier according to a proportion, wherein the mixing proportion is 78% of the silver powder, 6% of the glass powder and 16% of the organic carrier, uniformly stirring, and then obtaining conductive paste (silver paste) through a three-roller mill, wherein the square resistance range is 7.9mΩ/≡.
Example 5
Dissolving 20g of silver oxalate in 250g of deionized water, and adding 4g of citric acid into the silver oxalate solution; dissolving 5g of 30% hydrogen peroxide in 250g of deionized water to prepare a reducer solution; adding an ammonia water solution into the silver oxalate solution to adjust the pH value to 11, and stirring to clarify the solution, wherein the concentration of silver ions in the silver ion-containing solution is 0.53mol/L, and the dispersing agent is 20wt% of the silver source; adding 20% hydrogen peroxide solution into 20% silver nitrate solution, stirring and reducing fully, adding the rest silver nitrate solution and hydrogen peroxide solution into the reaction solution by using a peristaltic pump after 10min, continuing stirring and reducing, wherein the stirring speed is 800r/min, and the reaction temperature is controlled at 55 ℃.
After the reaction is finished, the solid-liquid separation of the reaction liquid is carried out, the surface impurities are removed by washing with deionized water and ethanol, and the silver powder is obtained by drying in a drying oven at 75 ℃ for 2.5 h.
Mixing the silver powder with 83% of silver powder, 4% of glass powder and 13% of organic carrier according to a proportion, stirring uniformly, and then obtaining conductive paste (silver paste) through a three-roller mill, wherein the square resistance range is 9.2mΩ/≡.
Experimental comparative description
In order to control the silver powder prepared by different reaction acid-base properties, the morphology of the silver powder prepared in comparative example 1 was compared with the silver powder prepared in examples 1 to 5 in comparative example 1.
Comparative example 1
Adding 10g of silver nitrate into 250g of deionized water, fully stirring and dissolving, and adding 1g of polyvinylpyrrolidone into the silver nitrate solution; dissolving 6.5g of ascorbic acid in 250g of deionized water to prepare a reducing agent solution; adding 20% of ascorbic acid solution into 20% of silver nitrate solution, fully stirring and reducing, adding the rest silver nitrate solution and the ascorbic acid solution into the reaction solution by using a peristaltic pump after 20min, and continuously stirring and reducing. After the reaction is completed, the solid-liquid separation of the reaction liquid is carried out, the surface impurities are removed by washing with deionized water and ethanol, the silver powder is obtained by drying in an oven at 80 ℃ for 2 hours, and the scanning electron microscope picture is shown in figure 4, and the structure is similar to a sphere.
TABLE 1
The silver powder prepared by the method is of a micron-sized sheet structure, has good uniformity and is suitable for industrialized large-scale stable production.
Claims (6)
1. The preparation method of the flake silver powder is characterized by preparing micron flake silver powder and comprises the following steps of:
s1, dissolving a silver source in deionized water to prepare a silver ion-containing solution, and dissolving a reducing agent in the deionized water to obtain a reducing agent solution, wherein the concentration range of silver ions in the silver ion-containing solution is 0.1-2mol/L;
s2, preparing pH regulating solution, adding the pH regulating solution into silver ion-containing solution, and regulating the pH value of the solution to 8-12;
s3, adding the dispersing agent into the silver ion-containing solution, and uniformly stirring;
s4, fully mixing and reducing the silver ion-containing solution and the reducing agent solution in the stirring process at the temperature of 20-60 ℃ to obtain silver particles, adding part of the reducing agent solution into part of the silver ion-containing solution in the mixing process, fully reducing and stirring, simultaneously adding the rest of the reducing agent solution and the silver ion solution into a system, continuously stirring and reducing until the reaction is finished, carrying out solid-liquid separation on the reaction liquid, and washing and drying to obtain the flaky silver powder;
in the step S1, the silver source is one or two of silver nitrate and silver oxalate;
in the step S1, the reducing agent comprises one of ascorbic acid, glucose, hydrazine hydrate or hydrogen peroxide, water is taken as a solvent, and the adding amount of the reducing agent is 1-2 times of the adding amount of the reducing agent relative to silver ions;
in the step S2, the pH regulating solution is an alkaline regulator, and the alkaline regulator is one or a mixture of ammonia water, sodium hydroxide and potassium hydroxide;
in the step S4, the ratio of the reducing agent solution to the silver ion-containing solution is 20% -80% for the first time, after the reducing agent solution and the silver ion-containing solution are fully reduced and stirred for a period of time, the rest reducing agent solution and the silver ion-containing solution are simultaneously added into a system which is reacted completely through a peristaltic pump to be reduced to obtain silver particles, the sample adding rate of the peristaltic pump is kept consistent, and the reaction temperature is controlled at 20-60 ℃.
2. The method for preparing plate-like silver powder according to claim 1, wherein the dispersant in step S3 comprises any one of citric acid, sodium citrate, polyvinylpyrrolidone, polymethacrylamide and ethylcellulose, and the dispersant content is 1wt% to 30wt% of the silver source.
3. The method for producing a plate-like silver powder according to claim 2, characterized in that the dispersant is polyvinylpyrrolidone; after the reaction is finished and the solid-liquid separation is carried out on the reaction liquid, deionized water is firstly used for cleaning 3-5 times, then ethanol is used for cleaning 1 time to remove surface impurities, and the content of the dispersing agent is 10-20wt% of the silver source.
4. The preparation method of the flake silver powder according to claim 2, wherein the dispersing agent is ethyl cellulose, and the ethyl cellulose is added into the silver ion solution after being dissolved by an organic solvent; after the reaction is finished, the solid-liquid separation of the reaction liquid is carried out, and deionized water is used for cleaning for 1 time to remove surface impurities.
5. Silver powder produced on the basis of a process for producing plate-like silver powder, characterized in that it is produced according to the process according to any one of claims 1 to 4, the plate-diameter distribution of the silver powder being 1.0 to 5.0 μm and the plate thickness being less than 200nm.
6. The conductive paste is characterized in that 75-85% of silver powder, 3-7% of glass powder and 12-18% of organic carrier are mixed uniformly and then pass through a rolling mill to obtain the conductive paste, wherein the square resistance range is 6-10mΩ/≡.
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