CN114871442B - Process for preparing superfine silver powder by utilizing composite reducing agent - Google Patents
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 67
- 239000003638 chemical reducing agent Substances 0.000 title claims abstract description 24
- 239000002131 composite material Substances 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims abstract description 54
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000003756 stirring Methods 0.000 claims abstract description 30
- 238000001035 drying Methods 0.000 claims abstract description 29
- 239000011668 ascorbic acid Substances 0.000 claims abstract description 27
- 235000010323 ascorbic acid Nutrition 0.000 claims abstract description 27
- 229960005070 ascorbic acid Drugs 0.000 claims abstract description 27
- 238000002360 preparation method Methods 0.000 claims abstract description 21
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000001514 detection method Methods 0.000 claims abstract description 17
- 230000009467 reduction Effects 0.000 claims abstract description 14
- 239000007791 liquid phase Substances 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 9
- 238000003921 particle size analysis Methods 0.000 claims abstract description 4
- 239000000243 solution Substances 0.000 claims description 120
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 87
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 58
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 57
- 238000006243 chemical reaction Methods 0.000 claims description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 49
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 42
- 239000008213 purified water Substances 0.000 claims description 36
- 238000005406 washing Methods 0.000 claims description 36
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 29
- 235000019441 ethanol Nutrition 0.000 claims description 28
- 239000000843 powder Substances 0.000 claims description 26
- 238000002474 experimental method Methods 0.000 claims description 25
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 claims description 21
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 claims description 21
- 239000011780 sodium chloride Substances 0.000 claims description 21
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 claims description 21
- 238000004458 analytical method Methods 0.000 claims description 19
- 238000001556 precipitation Methods 0.000 claims description 17
- 239000002244 precipitate Substances 0.000 claims description 16
- 239000006228 supernatant Substances 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 15
- 230000001376 precipitating effect Effects 0.000 claims description 15
- 229910052709 silver Inorganic materials 0.000 claims description 14
- 239000004332 silver Substances 0.000 claims description 14
- 229910021607 Silver chloride Inorganic materials 0.000 claims description 13
- 239000002270 dispersing agent Substances 0.000 claims description 13
- 239000008098 formaldehyde solution Substances 0.000 claims description 13
- 239000011259 mixed solution Substances 0.000 claims description 13
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims description 13
- 238000005245 sintering Methods 0.000 claims description 10
- 238000005303 weighing Methods 0.000 claims description 10
- 230000000052 comparative effect Effects 0.000 claims description 8
- 150000002500 ions Chemical class 0.000 claims description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- 230000035484 reaction time Effects 0.000 claims description 7
- 230000000630 rising effect Effects 0.000 claims description 7
- 101710134784 Agnoprotein Proteins 0.000 claims description 3
- BDAGIHXWWSANSR-UHFFFAOYSA-N Formic acid Chemical compound OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 3
- 239000003153 chemical reaction reagent Substances 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 235000019253 formic acid Nutrition 0.000 claims description 3
- 238000007865 diluting Methods 0.000 claims description 2
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 claims description 2
- 239000000047 product Substances 0.000 claims description 2
- 102220043159 rs587780996 Human genes 0.000 abstract description 6
- 239000002245 particle Substances 0.000 abstract description 4
- 239000002002 slurry Substances 0.000 abstract description 4
- 238000010923 batch production Methods 0.000 abstract description 3
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000003985 ceramic capacitor Substances 0.000 abstract description 3
- 239000013049 sediment Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 3
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000011946 reduction process Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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
- B22F1/065—Spherical 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
- H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
Abstract
The invention discloses a process for preparing superfine silver powder by utilizing a composite reducing agent, which belongs to the technical field of superfine silver powder, and comprises the steps of adding the composite reducing agent into a liquid phase for reduction for one time, carrying out particle size analysis, specific surface detection and conductive paste preparation, and using 85% C6H15NO3 (triethanolamine): 37% -40% hcho (formaldehyde): 25% c6h8o6 (ascorbic acid) =20: 4:3, adding liquid phase reduction once, in PH=12-13 alkaline environment, stirring at 70 ℃ at a speed of 100r/min, reducing to obtain gray black approximate sphere, drying at 80 ℃ to obtain particle size D50=0.5-0.75 um, preparing conductive slurry for buzzers, ceramic capacitors and piezoresistors, detecting various indexes, sending to customers in batch production, obtaining economic benefit, simple and convenient process steps, low cost and good reproduction operability.
Description
Technical Field
The invention relates to the technical field of superfine silver powder, in particular to a process for preparing superfine silver powder by using a composite reducing agent.
Background
The superfine silver powder for the electronic paste is reported to be prepared by a single reducing agent or multiple reducing agents in a step-by-step liquid phase reduction method, the crystallization speed and the agglomeration growth speed are inconsistent in the liquid phase reduction process, the crystallinity of the produced nanometer superfine silver powder is high, but the irregular surface of the produced nanometer superfine silver powder is not smooth, the shrinkage rate is high in the actual sintering process of the conductive paste, the dispersion type is general, the particle size is uneven, hard agglomeration in the reduction process and the drying process exists, the process processing difficulty is brought to the rolling of the conductive paste, and the silver surface compactness after printing and sintering is poor.
Disclosure of Invention
The invention aims to provide a process for preparing superfine silver powder by using a composite reducing agent, which aims to solve the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions: a process for preparing superfine silver powder by using a composite reducing agent comprises the following steps of adding the composite reducing agent into a liquid phase for reduction at one time, performing particle size analysis, specific surface detection and preparing conductive slurry:
s1, preparation of experimental reagent
Preparing 15% sodium hydroxide solution, wherein the total amount of the preparation is 2500 g; preparing rosin solution, and preparing 5 parts; preparing 25% ascorbic acid solution, and 5 parts; preparing 25% sodium chloride solution;
s2, preparation of silver nitrate solution
Preparing 17% silver nitrate solution according to the flow of international silver, adding purified water, adding nitric acid, heating, dissolving completely, diluting purified water and preparing silver nitrate solution, and weighing 4 parts according to 3000 ml;
s3, silver powder preparation
S301, taking 3000ml of 17% silver nitrate solution, and dripping 500ml of 15% sodium hydroxide solution for 15 minutes, wherein PH=12-13;
s302, adding a gram of rosin ethanol solution as a dispersing agent, and heating to 70 ℃;
s303, 200 g of 85% analysis alcohol-level triethanolamine solution, 40 g of 37% -40% analysis alcohol-level formaldehyde solution and 30 g of 25% concentration ascorbic acid solution are added at one time, the mixed solution is fully stirred, the stirring speed is 100r/min, and the reaction time is 10-15 minutes;
s304, observing and detecting whether the reaction is complete, adding purified water at normal temperature for washing after the reaction is complete, precipitating for 30 minutes, pouring out supernatant, washing for 4-5 times until the final detection conductivity of washing water is 20US/CM, and drying and crushing in a drying oven to obtain silver powder;
s4, performance comparison
And (3) performing a comparison experiment, detecting the performance of the silver powder prepared in the step (S3), and judging the excellent performance of the product.
In a preferred embodiment, in step S1, the 15% sodium hydroxide solution is prepared by: accurately weighing 15 g of sodium hydroxide and 85 g of purified water, slowly pouring the purified water into the container while stirring the sodium hydroxide until the purified water is completely dissolved; the preparation method of the rosin solution comprises the following steps: weighing 3.24 g of rosin and 50 g of absolute ethyl alcohol to dissolve completely; the preparation method of the 25% ascorbic acid solution comprises the following steps: 25 g of ascorbic acid and 75 g of purified water are weighed and heated to 60 ℃ to be completely dissolved; the preparation method of the 25% sodium chloride solution comprises the following steps: 25 g of sodium chloride solution was weighed and dissolved completely with 75 g of purified water under stirring.
In a preferred embodiment, in step S2, the silver nitrate solution is prepared by adding 30 kg of national standard silver to 65-68% analytical alcohol grade HNO 3 30L, heating and maintaining the temperature at 60 ℃ until the silver is completely dissolved, discharging and filtering, adding purified water to 360L to obtain 17% silver nitrate solution, wherein the reaction equation of silver and nitric acid is as follows:
3AG+4HNO 3 (lean) =3ag (NO 3 ) 2 +NO↑+2H 2 O；
AG+2HNO 3 (Strong) =ag (NO 3 ) 2 +NO 2↑ +H 2 O。
In a preferred embodiment, in step S3, silver nitrate reacts with sodium hydroxide, formaldehyde, ascorbic acid, and triethanolamine as follows:
AGNO 3 +NaOH＝NaNO 3 +AGOH (precipitation)
2AG 2+ +HCHO+H 2 O＝2AG↓+2H + +HCOOH (formaldehyde reduction ion type)
2AG 2+ +C 6 H 8 O 6 ＝2AG↓+2H + +C 6 H 6 O 6 (ascorbic acid reduction ion type)
(aminotriethanol) +3H 2 O (triethanolamine reduction ion type)
In a preferred embodiment, in step S304, the method for observing whether the reaction is complete is as follows: observing the powder to turn grey black, raising the temperature to above 80 ℃, scooping the reaction powder to precipitate the solution, pouring the solution into a 50ml beaker which is ready for 25% sodium chloride solution, and if white AGCL silver chloride precipitates, continuing the reaction until no precipitate exists at all, and ensuring that the reaction is finished.
In a preferred embodiment, in step S304, the silver powder obtained has a specific surface area of d50=0.5 UM, a specific surface area of 5.5m2/g, a burn-out of 99.5%, and a bulk density of 2.3g/ml.
In a preferred embodiment, in step S4, the comparison test includes a first comparison test, a second comparison test, a third comparison test and a reproduction test, wherein,
the content of the first comparison experiment is as follows: 3000ml of 17% silver nitrate solution is added with 500ml of 15% sodium hydroxide solution for 15 minutes, PH=12-13, 53.24 g of rosin ethanol solution is added as a dispersing agent, the temperature is raised to 70 ℃, 200 g of 85% analysis alcohol-grade triethanolamine solution and 70 g of 37% -40% analysis alcohol formaldehyde solution are added at one time, the mixed solution is fully stirred, the stirring speed is 100r/min, the reaction time is 10-15 minutes, the powder color is observed to turn to black, the temperature is raised to more than 80 ℃, the scooped reaction powder supernatant is poured into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride precipitates, the reaction is required to be continued until the precipitation is completely absent, the transparency is ensured, the reaction is finished, purified water is added at normal temperature after the reaction is completed, the supernatant is poured out after 30 minutes of precipitation, the supernatant is washed for 4-5 times until finally the washing water is detected to be at 20US/CM, and the silver powder is obtained after drying and crushing in a drying box.
In a preferred embodiment, the content of the second comparative experiment is: 3000ml of 17% silver nitrate solution is added with 500ml of 15% sodium hydroxide solution for 15 minutes, PH=12-13, 53.24 g of rosin ethanol solution is added as a dispersing agent, the temperature is raised to 70 ℃, 200 g of 85% analysis alcohol-grade triethanolamine solution, 50 g of 37% -40% analysis alcohol formaldehyde solution and 20 g of 25% ascorbic acid solution are added at one time, the mixed solution is fully stirred, the stirring speed is 100r/min, the reaction time is 10-15 minutes, the powder color is observed to turn black, the temperature is raised to above 80 ℃, the scooped reaction powder is poured into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride precipitation is required to continue to react until no precipitation is completely, the reaction is transparent, the reaction is proved to be finished, purified water is directly added for washing at normal temperature, the precipitation is carried out for 30 minutes, the supernatant is poured out, the washing is carried out for 4-5 times until the final washing water detection conductivity is 20US/CM, and the silver powder is dried and crushed in a drying box.
In a preferred embodiment, the third comparative experiment comprises the following steps: 3000ml of 17% silver nitrate solution is added with 500ml of 15% sodium hydroxide solution for 15 minutes, PH=12-13, 53.24 g of rosin ethanol solution is added as a dispersing agent, the temperature is raised to 70 ℃, 200 g of 85% analysis alcohol-grade triethanolamine solution, 30 g of 37% -40% analysis alcohol formaldehyde solution and 40 g of 25% ascorbic acid solution are added at one time, the mixed solution is fully stirred, the stirring speed is 100r/min, the reaction time is 10-15 minutes, the powder color is observed to turn black, the temperature is raised to above 80 ℃, the scooped reaction powder is poured into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride precipitation is required to continue to react until no precipitation is completely, the reaction is transparent, the reaction is proved to be finished, purified water is directly added for washing at normal temperature, the precipitation is carried out for 30 minutes, the supernatant is poured out, the washing is carried out for 4-5 times until the final washing water detection conductivity is 20US/CM, and the silver powder is obtained after drying and crushing in a drying box.
In a preferred embodiment, the content and parameters of the reproduction experiment are identical to those of step S3; and step S3, sintering and detecting silver powder prepared in the comparative experiment by using conductive paste.
The invention has the beneficial effects that:
with 85% c6h15no3 (triethanolamine): 37% -40% hcho (formaldehyde): 25% c6h8o6 (ascorbic acid) =20: 4:3, adding liquid phase reduction once, in PH=12-13 alkaline environment, stirring at 70 ℃ at a speed of 100r/min, reducing to obtain gray black approximate sphere, drying at 80 ℃ to obtain particle size D50=0.5-0.75 um, preparing conductive slurry for buzzers, ceramic capacitors and piezoresistors, detecting various indexes, sending to customers in batch production, obtaining economic benefit, simple and convenient process steps, low cost and good reproduction operability.
Drawings
Fig. 1 is a schematic diagram of an electron microscope structure of an ultrafine silver powder prepared by using a composite reducing agent according to an embodiment of the invention.
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 invention without making any inventive effort, are intended to be within the scope of the invention.
Examples: as shown in fig. 1, the present invention provides a process for preparing ultrafine silver powder using a composite reducing agent, which performs particle size analysis, specific surface detection and conductive paste preparation by adding the composite reducing agent into a liquid phase for one time, comprising the following process steps:
s1, preparation of experimental reagent
Preparing 15% sodium hydroxide solution, accurately weighing 15 g of sodium hydroxide and 85 g of purified water, slowly pouring the purified water into the solution while stirring the sodium hydroxide until the solution is completely dissolved, and preparing 2500 g of total amount;
preparing rosin solution, namely weighing 3.24 g of rosin and 50 g of absolute ethyl alcohol to be completely dissolved, and preparing 5 parts;
preparing 25% ascorbic acid solution, namely, 25 g of ascorbic acid and 75 g of purified water are heated to 60 ℃ to be completely dissolved, and 5 parts of ascorbic acid solution is prepared;
preparing 25% sodium chloride solution, weighing 25 g of sodium chloride solution and 75 g of purified water, and stirring to dissolve completely;
s2, preparation of silver nitrate solution
The 17% silver nitrate solution and the nitric acid are prepared according to the flow of international silver, purified water, nitric acid, heating, complete dissolution, dilution of the purified water and silver nitrate solutionThe silver solution standard is that 30 kg of national standard silver is added into 65-68% of HNO for analysis of alcohol grade 3 30L, heating and maintaining the temperature at 60 ℃ until the silver is completely dissolved, discharging and filtering, adding purified water to 360L to obtain 17% silver nitrate solution, weighing 4 parts according to 3000ml, wherein the reaction equation of silver and nitric acid is as follows:
3AG+4HNO 3 (lean) =3ag (NO 3 ) 2 +NO↑+2H 2 O；
AG+2HNO 3 (Strong) =ag (NO 3 ) 2 +NO 2↑ +H 2 O；
S3, silver powder preparation
S301, 3000ml of 17% silver nitrate solution is dripped for 15 minutes by 500ml of 15% sodium hydroxide solution, and PH=12-13, and the reaction equation is as follows: AGNO 3 +NaOH＝NaNO 3 +agoh (precipitate);
s302, adding a gram of rosin ethanol solution as a dispersing agent, and heating to 70 ℃;
s303, 200 g of 85% analysis alcohol-level triethanolamine solution, 40 g of 37% -40% analysis alcohol-level formaldehyde solution and 30 g of 25% concentration ascorbic acid solution are added at a time, the mixed solution is fully stirred, the stirring speed is 100r/min, the reaction time is 10-15 minutes, and the reaction equation is as follows:
2AG 2+ +HCHO+H 2 O＝2AG↓+2H + +HCOOH (formaldehyde reduction ion type)
2AG 2+ +C 6 H 8 O 6 ＝2AG↓+2H + +C 6 H 6 O 6 (ascorbic acid reduction ion type)
(aminotriethanol) +3H 2 O (triethanolamine reducing ion type);
s304, observing and detecting whether the reaction is complete, observing that the powder turns grey black, rising the temperature to more than 80 ℃, scooping reaction powder sediment liquid into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride is precipitated, continuing the reaction until no precipitate exists, clearing the sediment until the sediment is transparent, proving that the reaction is finished, adding purified water in a normal temperature state for washing after the reaction is complete, precipitating for 30 minutes, pouring the sediment liquid out, washing for 4-5 times until the final washing water detection conductivity is 20US/CM, and drying and crushing the sediment liquid in a drying box to obtain silver powder;
through detection, the silver powder obtained in the embodiment has the parameters of d50=0.5um, specific surface area=5.5m2/g, burning loss=99.5%, apparent density=2.3 g/ml, and is used for sintering detection of conductive paste, and each index is excellent.
To further embody the properties of the silver powder prepared in this example, and its reproducibility, a comparative experiment one, a comparative experiment two, a comparative experiment three, and a reproducibility experiment were performed, in which,
the content of the comparative experiment one is: adding 500ml of 15% sodium hydroxide solution into 3000ml of 17% silver nitrate solution to be precipitated for 15 minutes, adding 53.24 g of rosin ethanol solution as a dispersing agent, heating to 70 ℃, adding 200 g of 85% analytical alcohol-grade triethanolamine solution and 70 g of 37% -40% analytical alcohol-formaldehyde solution at one time, fully stirring the mixed solution, stirring at 100r/min for 10-15 minutes, observing that the powder turns grey black, rising the temperature to be above 80 ℃, scooping reaction powder supernatant into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride precipitates, continuing to react until the precipitate is completely absent, precipitating until transparency, proving that the reaction is finished, adding purified water for washing at normal temperature after the reaction is complete, precipitating for 30 minutes, pouring the supernatant out, washing for 4-5 times until the final washing water is detected to be conductive at 20US/CM, drying and crushing in a drying box to obtain silver powder, wherein the silver powder performance is D50=2.0UM, the specific surface area=4m2/g, the loss=99.5wt% and the density=1.6g/g, and using the silver powder for detecting the conductivity difference in sintering paste ml;
comparison experiment II: adding 500ml of 15% sodium hydroxide solution into 3000ml of 17% silver nitrate solution to be precipitated for 15 minutes, adding 53.24 g of rosin ethanol solution as a dispersing agent, heating to 70 ℃, adding 200 g of 85% analysis alcohol-grade triethanolamine solution, 50 g of 37% -40% analysis alcohol-formaldehyde solution and 20 g of 25% ascorbic acid solution at one time, fully stirring the mixed solution, stirring at a stirring speed of 100r/min, reacting for 10-15 minutes, observing the powder to turn grey and black, rising the temperature to be more than 80 ℃, pouring scooped reaction powder to a 50ml beaker which is ready for a 25% sodium chloride solution, if white AGCL silver chloride precipitation is needed to be reacted until no precipitation is completely, precipitating until transparent, proving that the reaction is finished, directly adding purified water at normal temperature for washing, precipitating for 30 minutes, pouring the supernatant, washing for 4-5 times until the final washing water detection conductivity is 20US/CM, putting into a drying box for drying and crushing, and obtaining silver powder performance of D50=1.2 silver powder, specific surface area=4.5 m2/g, burning loss=99.5%, and carrying out 1.8g for detecting the general conductive paste sintering effect;
comparison experiment three: adding 500ml of 15% sodium hydroxide solution into 3000ml of 17% silver nitrate solution to be precipitated for 15 minutes, adding 53.24 g of rosin ethanol solution as a dispersing agent, heating to 70 ℃, adding 200 g of 85% analytical alcohol-grade triethanolamine solution, 30 g of 37% -40% analytical alcohol-formaldehyde solution and 40 g of 25% ascorbic acid solution at one time, fully stirring the mixed solution, stirring at a stirring speed of 100r/min, reacting for 10-15 minutes, observing that the powder turns grey and black, rising the temperature to be more than 80 ℃, pouring scooped reaction powder into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride precipitate is required to be reacted until no precipitate is completely precipitated, and precipitating until transparent, proving that the reaction is finished, directly adding purified water at normal temperature for washing, precipitating for 30 minutes, pouring the supernatant, washing for 4-5 times until the final washing water detection conductivity is 20US/CM, putting into a drying box for drying and crushing, and obtaining silver powder performance D50=0.6UM silver powder, specific surface area=5m2/g, and firing=99.5%, and 1.9g for detecting the density of the light conductivity, the conductive paste, the density and the good compactness, the good printing performance, and the good brightness;
reproduction experiment: 3000ml of 17% silver nitrate solution is added with 500ml of 15% sodium hydroxide solution for 15 minutes, PH=12-13, 53.24 g of rosin ethanol solution is added as a dispersing agent, the temperature is raised to 70 ℃, 200 g of 85% analysis alcohol-grade triethanolamine solution, 40 g of 37% -40% analysis alcohol-formaldehyde solution and 30 g of 25% ascorbic acid solution are added at one time, the mixed solution is fully stirred, the stirring speed is 100r/min, the reaction time is 10-15 minutes, the powder color is observed to turn black, the temperature is raised to above 80 ℃, the scooping reaction powder is poured into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride precipitation is needed to continue reacting until no precipitation is completely, the transparent precipitation is confirmed, the reaction is finished, purified water is directly added for washing at normal temperature, the precipitation is poured for 30 minutes, the supernatant is washed for 4-5 times until the final washing water detection conductivity is 20US/CM, the obtained by drying and crushing in a drying box, the specific surface area=5.5 m, the burning loss=99.5%, the apparent density=2.3 g is detected, and the conductive paste is used for carrying out sintering, and the conductive paste is similar to the sintering example, and the conductive paste is excellent in various indexes, and the sintering example is obtained.
The comprehensive results after the performance detection of the silver powder prepared for many times by adopting the embodiment are shown in the following table:
to sum up, 85% c6h15no3 (triethanolamine): 37% -40% hcho (formaldehyde): 25% c6h8o6 (ascorbic acid) =20: 4:3, adding liquid phase reduction once, in PH=12-13 alkaline environment, stirring at 70 ℃ at a speed of 100r/min, reducing to obtain gray black approximate sphere, drying at 80 ℃ to obtain particle size D50=0.5-0.75 um, preparing conductive slurry for buzzers, ceramic capacitors and piezoresistors, detecting various indexes, sending to customers in batch production, obtaining economic benefit, simple and convenient process steps, low cost and good reproduction operability.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. A process for preparing superfine silver powder by using a composite reducing agent comprises the steps of adding the composite reducing agent into a liquid phase for reduction at one time, performing particle size analysis, specific surface detection and conductive paste preparation, and is characterized by comprising the following steps:
s1, preparation of experimental reagent
Preparing 15% sodium hydroxide solution, wherein the total amount of the preparation is 2500 g; preparing rosin solution, and preparing 5 parts; preparing 25% ascorbic acid solution, and 5 parts; preparing 25% sodium chloride solution;
s2, preparation of silver nitrate solution
Preparing 17% silver nitrate solution according to the flow of international silver, adding purified water, adding nitric acid, heating, dissolving completely, diluting purified water and preparing silver nitrate solution, and weighing 4 parts according to 3000 ml;
s3, silver powder preparation
S301, taking 3000ml of 17% silver nitrate solution, and dripping 500ml of 15% sodium hydroxide solution for 15 minutes, wherein PH=12-13;
s302, adding a gram of rosin ethanol solution as a dispersing agent, and heating to 70 ℃;
s303, 200 g of 85% analysis alcohol-level triethanolamine solution, 40 g of 37% -40% analysis alcohol-level formaldehyde solution and 30 g of 25% concentration ascorbic acid solution are added at one time, the mixed solution is fully stirred, the stirring speed is 100r/min, and the reaction time is 10-15 minutes;
s304, observing and detecting whether the reaction is complete, adding purified water at normal temperature for washing after the reaction is complete, precipitating for 30 minutes, pouring out supernatant, washing for 4-5 times until the final detection conductivity of washing water is 20US/CM, and drying and crushing in a drying oven to obtain silver powder;
s4, performance comparison
And (3) performing a comparison experiment, detecting the performance of the silver powder prepared in the step (S3), and judging the excellent performance of the product.
2. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 1, wherein: in the step S1, the preparation method of the 15% sodium hydroxide solution comprises the following steps: accurately weighing 15 g of sodium hydroxide and 85 g of purified water, slowly pouring the purified water into the container while stirring the sodium hydroxide until the purified water is completely dissolved; the preparation method of the rosin solution comprises the following steps: weighing 3.24 g of rosin and 50 g of absolute ethyl alcohol to dissolve completely; the preparation method of the 25% ascorbic acid solution comprises the following steps: 25 g of ascorbic acid and 75 g of purified water are weighed and heated to 60 ℃ to be completely dissolved; the preparation method of the 25% sodium chloride solution comprises the following steps: 25 g of sodium chloride solution was weighed and dissolved completely with 75 g of purified water under stirring.
3. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 1, wherein: in the step S2, the standard of the silver nitrate solution is that 30 kg of national standard silver is added into 65-68% of HNO of analytical alcohol grade 3 30L, heating and maintaining the temperature at 60 ℃ until the silver is completely dissolved, discharging and filtering, adding purified water to 360L to obtain 17% silver nitrate solution, wherein the reaction equation of silver and nitric acid is as follows:
3AG+4HNO 3 (lean) =3ag (NO 3 ) 2 +NO↑+2H 2 O；
AG+2HNO 3 (Strong) =ag (NO 3 ) 2 +NO 2↑ +H 2 O。
4. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 1, wherein: in step S3, the reaction equation of silver nitrate with sodium hydroxide, formaldehyde, ascorbic acid, and triethanolamine is as follows:
AGNO 3 +NaOH＝NaNO 3 +AGOH (precipitation)
2AG 2+ +HCHO+H 2 O＝2AG↓+2H + +HCOOH (formaldehyde reduction ion type)
2AG 2+ +C 6 H 8 O 6 ＝2AG↓+2H + +C 6 H 6 O 6 (ascorbic acid reduction ion type)
5. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 1, wherein: in step S304, the method for observing whether the reaction is complete is as follows: observing the powder to turn grey black, raising the temperature to above 80 ℃, scooping the reaction powder to precipitate the solution, pouring the solution into a 50ml beaker which is ready for 25% sodium chloride solution, and if white AGCL silver chloride precipitates, continuing the reaction until no precipitate exists at all, and ensuring that the reaction is finished.
6. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 1, wherein: in step S304, silver powder parameters were d50=0.5 UM, specific surface area=5.5 m2/g, burn-out=99.5%, apparent density=2.3 g/ml.
7. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 1, wherein: in step S4, the comparison experiment includes a first comparison experiment, a second comparison experiment, a third comparison experiment, and a reproduction experiment, wherein,
the content of the first comparison experiment is as follows: adding 500ml of 15% sodium hydroxide solution into 500ml of 3000ml of 17% silver nitrate solution to precipitate for 15 minutes, adding 53.24 g of rosin ethanol solution as a dispersing agent, heating to 70 ℃, adding 200 g of 85% analysis alcohol-grade triethanolamine solution and 70 g of 37% -40% analysis alcohol formaldehyde solution at one time, fully stirring the mixed solution, stirring at 100r/min for 10-15 minutes, observing the powder to turn grey black, rising the temperature to be more than 80 ℃, scooping reaction powder supernatant into a 50ml beaker which is ready for 25% sodium chloride solution, if white AGCL silver chloride precipitates, continuing the reaction until the precipitation is completely absent, precipitating until transparency, proving that the reaction is finished, adding purified water for washing at normal temperature after the reaction is complete, precipitating for 30 minutes, pouring the supernatant, washing for 4-5 times until the final washing water detects the conductivity at 20US/CM, and drying and crushing in a drying box to obtain silver powder.
8. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 7, wherein: the content of the second comparison experiment is as follows: adding 500ml of 15% sodium hydroxide solution into 3000ml of 17% silver nitrate solution to precipitate for 15 minutes, adding 53.24 g of rosin ethanol solution as a dispersing agent, heating to 70 ℃, adding 200 g of 85% analytical alcohol-grade triethanolamine solution, 50 g of 37% -40% analytical alcohol formaldehyde solution and 20 g of 25% ascorbic acid solution at one time, fully stirring the mixed solution, stirring at a speed of 100r/min, reacting for 10-15 minutes, observing that the powder turns grey and black, rising the temperature to above 80 ℃, scooping reaction powder to precipitate into a 50ml beaker which is ready for 25% sodium chloride solution, continuing to react until no precipitate exists if white AGCL silver chloride precipitate is required, precipitating until transparent, proving that the reaction is finished, directly adding purified water at normal temperature for washing, precipitating for 30 minutes, pouring the supernatant, washing for 4-5 times until the final washing water detection conductivity is 20US/CM, and drying and crushing the silver powder in a drying box to obtain the silver powder.
9. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 7, wherein: the content of the third comparison experiment is as follows: adding 500ml of 15% sodium hydroxide solution into 3000ml of 17% silver nitrate solution to precipitate for 15 minutes, adding 53.24 g of rosin ethanol solution as a dispersing agent, heating to 70 ℃, adding 200 g of 85% analytical alcohol-grade triethanolamine solution, 30 g of 37% -40% analytical alcohol formaldehyde solution and 40 g of 25% ascorbic acid solution at one time, fully stirring the mixed solution, stirring at a speed of 100r/min, reacting for 10-15 minutes, observing that the powder turns grey and black, rising the temperature to above 80 ℃, scooping reaction powder to precipitate into a 50ml beaker which is ready for 25% sodium chloride solution, continuing to react until no precipitate exists if white AGCL silver chloride precipitate is required, precipitating until transparent, proving that the reaction is finished, directly adding purified water at normal temperature for washing, precipitating for 30 minutes, pouring the supernatant, washing for 4-5 times until the final washing water detection conductivity is 20US/CM, and drying and crushing the silver powder in a drying box to obtain the silver powder.
10. The process for preparing ultrafine silver powder by using a composite reducing agent as set forth in claim 7, wherein: the content and parameters of the reproduction experiment are identical to those of the step S3; and step S3, sintering and detecting silver powder prepared in the comparative experiment by using conductive paste.
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| JP2005146408A (en) * | 2003-10-22 | 2005-06-09 | Mitsui Mining & Smelting Co Ltd | Superfine silver particulate-stuck silver powder, and method for producing the superfine silver particulate-stuck silver powder |
| CN101716685A (en) * | 2009-12-14 | 2010-06-02 | 昆明理工大学 | Method for preparing spherical superfine silver powder by using chemical reduction method |
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| WO2021194061A1 (en) * | 2020-03-25 | 2021-09-30 | 엘에스니꼬동제련 주식회사 | Silver powder for conductive paste having improved viscosity stability, and preparation method therefor |
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| JP2005146408A (en) * | 2003-10-22 | 2005-06-09 | Mitsui Mining & Smelting Co Ltd | Superfine silver particulate-stuck silver powder, and method for producing the superfine silver particulate-stuck silver powder |
| CN101716685A (en) * | 2009-12-14 | 2010-06-02 | 昆明理工大学 | Method for preparing spherical superfine silver powder by using chemical reduction method |
| CN107457411A (en) * | 2017-06-15 | 2017-12-12 | 昆明理工大学 | A kind of method for preparing super fine silver powder |
| WO2021194061A1 (en) * | 2020-03-25 | 2021-09-30 | 엘에스니꼬동제련 주식회사 | Silver powder for conductive paste having improved viscosity stability, and preparation method therefor |
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