WO2022209613A1 - Procédé de fabrication d'un nanofil d'argent - Google Patents

Procédé de fabrication d'un nanofil d'argent Download PDF

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WO2022209613A1
WO2022209613A1 PCT/JP2022/009791 JP2022009791W WO2022209613A1 WO 2022209613 A1 WO2022209613 A1 WO 2022209613A1 JP 2022009791 W JP2022009791 W JP 2022009791W WO 2022209613 A1 WO2022209613 A1 WO 2022209613A1
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silver nanowires
silver
water
specific resistance
reprecipitation
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Japanese (ja)
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葵 長谷川
繁 山木
正彦 鳥羽
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昭和電工株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • 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
    • B22F1/062—Fibrous particles
    • 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
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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

Definitions

  • the present invention relates to a method for producing silver nanowires.
  • silver nanowires have attracted attention as a raw material for highly transparent and highly conductive thin films that can replace the ITO (indium tin oxide) films used in transparent electrodes such as touch panels.
  • Such silver nanowires are generally produced by a so-called polyol reduction method in which a silver compound is heated in the presence of polyvinylpyrrolidone and a polyol such as ethylene glycol (Patent Document 1, Non-Patent Document 1).
  • the synthetic solution contains a polyol solvent, a polymer used as a structure-directing agent, and by-product silver nanoparticles.
  • a polyol solvent a polymer used as a structure-directing agent
  • by-product silver nanoparticles degrade the transparency of the transparent conductive film, so it is desirable to remove them as much as possible.
  • the so-called reprecipitation method is suitable for large-scale purification.
  • acetone is used as a poor solvent and water (ion-exchanged water) is used as a good solvent, and the steps of precipitation/supernatant removal/resuspension are repeated several times to obtain a dispersion mainly containing silver nanowires. disclosed.
  • an object of the present invention is to provide a method for producing silver nanowires that can reduce the number of reprecipitation washings and efficiently remove silver nanoparticles from a coarse dispersion containing silver nanowires and silver nanoparticles. to do.
  • the present invention includes the following embodiments.
  • the reprecipitation washing step includes (c′) adding water having a specific resistance of less than 3.3 M ⁇ cm to the remaining precipitate to redisperse the precipitate in water to obtain a redispersion liquid.
  • step (c) When absorption based on silver nanoparticles near 405 nm is observed in the supernatant liquid generated in step (a) in a series of operations from the second time onwards, in step (c) after that, the specific resistance value is 18 M ⁇ cm or more.
  • the silver nanowires when producing silver nanowires by purifying a silver nanowire coarse dispersion containing silver nanowires and silver nanoparticles using a reprecipitation method, the silver nanowires are washed with a smaller number of reprecipitation washings than before. can be manufactured.
  • FIG. 10 is a diagram showing absorption spectrum measurement results of supernatant liquids removed in each supernatant removal step (b) in a series of operations of 3rd to 8th reprecipitation washings in the reprecipitation washing step of Example 4;
  • the method for producing silver nanowires according to the present embodiment includes a coarse dispersion preparation step of preparing a coarse dispersion containing silver nanowires and silver nanoparticles, and reprecipitation to refine the silver nanowires in the coarse dispersion. and a reprecipitation washing step, wherein the reprecipitation washing step has a series of operations consisting of the following steps (a), (b), and (c), and the series of operations is repeated multiple times. do.
  • the method for producing silver nanowires according to the present embodiment first has a coarse dispersion preparation step of preparing a coarse dispersion containing silver nanowires and silver nanoparticles.
  • This coarse dispersion preparation step includes a step of synthesizing the desired silver nanowires.
  • the process for synthesizing silver nanowires is not particularly limited, and known methods can be applied.
  • a first solution containing an ionic derivative containing a polyol as a solvent
  • a second solution containing a metal salt (silver nitrate) is added to the total number of moles of halogen atoms of the ionic derivative in the first solution and the number of metal atoms of the metal salt supplied for 1 minute.
  • the reaction pressure is usually normal pressure (atmospheric pressure).
  • the reaction solvent used in the above polyol reduction method includes polyols used as reducing agents, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1 , 2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, glycerin, etc., and at least one selected from the group consisting of these is preferred. Dihydric alcohols are more preferable from the viewpoint of avoiding high viscosity, and among these, ethylene glycol and propylene glycol are more preferable from the viewpoint of economy.
  • the reaction solution after the synthesis reaction contains by-produced silver nanoparticles in addition to the ionic derivative, structure-directing agent, and solvent used in the synthesis together with the desired silver nanowires.
  • Synthetic silver nanowires are metallic silver with diameters on the order of nanometers, and are conductive materials with linear shapes (including hollow tubular silver nanotubes).
  • the metal silver of the silver nanowire does not contain a metal oxide in terms of conductive performance, but if air oxidation cannot be avoided, a part (at least a part of the surface) may contain a silver oxide. .
  • the length (diameter) in the minor axis direction of the silver nanowires is preferably an average of 5 nm or more and 90 nm or less, more preferably an average of 10 nm or more and 85 nm or less, still more preferably an average of 10 nm or more and 70 nm or less, particularly preferably an average of 10 nm or more and 50 nm or less.
  • the length in the major axis direction is preferably 1 ⁇ m or more and 100 ⁇ m or less on average, more preferably 5 ⁇ m or more and 95 ⁇ m or less on average, still more preferably 5 ⁇ m or more and 70 ⁇ m or less on average, and particularly preferably 5 ⁇ m or more and 50 ⁇ m or less on average.
  • the term “silver nanowire” means that the aspect ratio represented by a/b is 5 or more, where a is the length in the major axis direction and b is the length (diameter) in the minor axis direction. It is preferably 10 or more, more preferably 50 or more, and even more preferably 100 or more.
  • the term “silver nanoparticles” as used herein means particles other than the above-mentioned “silver nanowires", has an aspect ratio of less than 5, and is a by-product of the synthesis of silver nanowires. It means a particulate one excluding "silver nanowires”.
  • the ionic derivative is a component that contributes to the growth of metal wires (silver nanowires), and can be applied as long as it is a compound that dissolves in a solvent and can dissociate halogen ions.
  • compounds are preferred.
  • Halogen ions are preferably at least one of chloride ions, bromide ions, and iodine ions, and more preferably contain a compound capable of dissociating chloride ions.
  • Halides of quaternary ammonium salts include quaternary alkylammonium salts having a total number of carbon atoms of 4 to 20 in the molecule (four alkyl groups are bonded to the nitrogen atom of the quaternary ammonium salt, and each alkyl group is which may be the same or different) are preferred, for example, quaternary ammonium chloride such as tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, octyltrimethylammonium chloride, hexadecyltrimethylammonium chloride Chlorides, and quaternary ammonium bromides such as tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, o
  • Ammonium salts obtained by reacting quaternary ammonium hydroxide with hydrogen chloride, hydrogen bromide, and hydrogen iodide can also be used. Since these are in a gaseous state at room temperature, they may be neutralized using an aqueous solution thereof in a polyol solvent, and water and excess hydrogen halide can be distilled off by heating after neutralization.
  • halides of quaternary alkylammonium salts having 4 to 16 total carbon atoms in the molecule are more preferable in terms of solubility and efficiency of use, and the longest alkyl chain attached to the nitrogen atom has the highest number of carbon atoms.
  • Halides of quaternary alkylammonium salts having a molecular weight of 12 or less, more preferably 8 or less, are more preferable in terms of efficiency in use because the molecular weight does not become particularly large.
  • tetramethylammonium chloride tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, Octyltrimethylammonium chloride and octyltrimethylammonium bromide are particularly preferred.
  • metal halides examples include alkali metal halides, alkaline earth metal halides, and metal halides of groups 3 to 12 of the long periodic table.
  • Alkali metal halides include alkali metal chlorides such as lithium chloride, sodium chloride and potassium chloride, alkali metal bromides such as lithium bromide, sodium bromide and potassium bromide, lithium iodide, sodium iodide and potassium iodide. and alkali metal iodides such as Alkaline earth metal halides include magnesium chloride, magnesium bromide and calcium chloride.
  • Metal halides of groups 3 to 12 of the long periodic table include ferric chloride, cupric chloride, ferric bromide, and cupric bromide. Any one of these may be used alone, or two or more of them may be used in combination.
  • a compound that dissociates chloride ions for the production of silver nanowires.
  • a compound that dissociates chlorine ions and at least one of a compound that dissociates bromide ions and a compound that dissociates iodine ions in combination.
  • the molar ratio of (A)/(B) is preferably 2-8, more preferably 3-6.
  • the structure-directing agent used in the synthesis is a compound that has the function of one-dimensionally defining the growth direction of the metal particles during synthesis.
  • the structure-directing agent preferentially or selectively adsorbs to specific crystal planes of the target grain and controls the growth orientation by suppressing the growth of the adsorbed planes.
  • This growth orientation can be controlled by adding a structure-directing agent to the polyols and adsorbing it on the surface of the silver nanowires to be produced.
  • the structure-directing agent is preferably a polymer having a weight-average molecular weight of more than 1,000, more preferably 2,000 or more, and even more preferably 10,000 or more.
  • the weight average molecular weight of the structure-directing agent is preferably 1,500,000 or less, more preferably 1,000,000 or less, and even more preferably 500,000 or less.
  • the structure-directing agent include poly-N-vinylpyrrolidone (PVP) and a 1:1 copolymer of N-vinylpyrrolidone and vinyl acetate.
  • the structure-directing agent controls the wire-like growth of silver nanowires during synthesis of silver nanowires, and also has the effect of preventing aggregation of the generated silver nanowires.
  • the structure directing agent is preferably contained in the coarse dispersion of silver nanowires in an amount of 0.5% by mass or more, more preferably 0.7 to 7% by mass, and still more preferably 1.0 to 5% by mass. By making it 0.5% by mass or more, aggregation does not occur even when a high-concentration dispersion such as a silver concentration of 1.0% or more is handled. On the other hand, if the concentration of the structure-directing agent is too high, the subsequent purification step will be prolonged and the productivity will be lowered.
  • the polyol in the silver nanowire crude dispersion which is the reaction solution obtained by the synthesis, is too large, the amount of the sedimentation solvent used in the reprecipitation washing step described later will increase, so the polyol is distilled off as necessary. Then, the silver nanowires may be concentrated to some extent (concentration step). However, if the distillation is carried out at an excessively high temperature, there is a risk of aggregation, so it is preferable to carry out the distillation at a pressure of 100 mmHg or less and a temperature of 150° C. or less.
  • a poor solvent for example, ethyl acetate
  • a sedimentation solvent for example, ethyl acetate
  • sedimenting silver nanowires and removing a polyol and a sedimentation solvent
  • concentration step is not essential and may be omitted.
  • the step of reprecipitating and washing the silver nanowires in the coarse dispersion prepared in the coarse dispersion preparing step is repeated multiple times.
  • the reprecipitation washing step consists of a series of steps (a), (b) and (c) below. That is, a series of steps performed in the order of (a) ⁇ (b) ⁇ (c) are repeated multiple times.
  • the re-dispersed liquid obtained in the (c) re-dispersion step is used in place of the coarsely dispersed liquid.
  • the coarse dispersion obtained by synthesizing silver nanowires contains, in addition to the target metal nanowires, a synthesis solvent, a polymer used as a structure-directing agent, and silver nanoparticles produced as a by-product during synthesis. Therefore, it is necessary to remove these impurities. Since the silver nanowires, silver nanoparticles, and the like are dispersed in the coarse dispersion, first, a sedimentation solvent is added to the coarse dispersion to sediment the precipitate containing the silver nanowires (precipitation step). Sedimentation of the precipitate can be performed by standing. The standing time is preferably 5 to 20 minutes. If the standing time is too short from this range, the precipitate may not settle completely, and if it is too long, aggregation may occur. The precipitate contains some silver nanoparticles along with the silver nanowires.
  • the precipitating solvent is a poor solvent in which the structure-directing agent has low solubility, and is preferably at least one of ketone-based solvents and organic ester-based solvents.
  • organic ester solvents include ethyl acetate, n-propyl acetate, isopropyl acetate, allyl acetate, n-butyl acetate, ethyl propionate, and propylene glycol monomethyl ether acetate.
  • these solvents acetone, methyl ethyl ketone, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, and propylene glycol monomethyl ether acetate are preferred from the viewpoint of sedimentation of metal nanowires and solubility in polyols.
  • the amount of the precipitation solvent to be used is preferably 50 to 2000 parts by mass, more preferably 70 to 600 parts by mass based on 100 parts by mass of the crude silver nanowire dispersion used.
  • a dispersant (among polymer dispersants, a nonionic dispersant that dissolves in a poor solvent) may be added to the sedimentation solvent (poor solvent).
  • examples include higher alcohol ethers, alkylphenyl ethers, fatty acid esters, polyhydric alcohol fatty acid ester derivatives, polyoxyethylene polyoxypropylene glycol, and glycerol fatty acid esters.
  • a supernatant is produced by producing a precipitate containing silver nanowires in the above (a) sedimentation step.
  • This supernatant contains silver nanoparticles by-produced during the synthesis of silver nanowires, a structure-directing agent dissolved in the dispersion medium (synthesis solvent) of the coarse dispersion, a sedimentation solvent, and the like.
  • a supernatant containing at least part of the silver nanoparticles is separated from the precipitate and removed (supernatant removing step).
  • a method for removing the supernatant is not particularly limited. For example, it can be removed by decantation treatment, or it can be removed by suction with a pump.
  • the sediment in the residue after separating and removing the supernatant contains some silver nanoparticles that have sedimented together with the silver nanowires.
  • water having a specific resistance of 3.3 M ⁇ cm or more is added to the precipitate, so that the silver nanowires and silver nanoparticles contained in the precipitate are separated with a good solvent.
  • a redispersed liquid is obtained by redispersing in a certain amount of water (redispersion step).
  • the good solvent means a dispersion medium capable of uniformly dispersing silver nanowires and silver nanoparticles, and a solvent capable of satisfactorily dissolving a structure-directing agent.
  • the silver nanoparticles mixed with the silver nanowires in the precipitate can be efficiently redispersed. can. From the results of Examples and Comparative Examples described later, the present inventors found that by controlling the resistivity value of water, the number of times of reprecipitation washing (repeating a series of steps (a), (b), and (c)) was higher than before. It has been found that n can be reduced.
  • the specific resistance value of this water is 3.3 M ⁇ cm or more, preferably 5.0 M ⁇ cm or more, and more preferably 18 M ⁇ cm water, so-called ultrapure water.
  • the silver nanowire ratio (number of silver nanowires/total number of particles) is 90 even if reprecipitation washing is repeated an industrially acceptable number of times, for example, 15 times. % not reached.
  • the purification method of the water is not particularly limited.
  • distillation of tap water (tap water), purification using an RO (reverse osmosis) membrane, ion exchange resin, or a combination thereof can be mentioned.
  • RO reverse osmosis
  • ion exchange resin ion exchange resin
  • the above water repeats reprecipitation washing (operation of a series of steps (a), (b), and (c)) n times (n represents an integer of 2 or more), and the same ratio is used in all steps (c) n times.
  • Waters of different resistivity values can be used, but combinations of waters of different resistivity values can also be used. It is preferable to use ultrapure water having a specific resistance of 18 M ⁇ cm or more at least once in the second and subsequent (c) redispersion steps. For example, in the initial stage when the structure-directing agent is mainly removed, ion-exchanged water with a specific resistance of 3.3 M ⁇ cm or more but a relatively small specific resistance is added to the silver nanoparticles in the (a) sedimentation step.
  • ultrapure water that has a relatively high specific resistance value of 18 M ⁇ cm or more after starting to be dispersed in the resulting supernatant.
  • specific resistance of water the greater the effect of dispersing the silver nanoparticles in the supernatant.
  • concentration of the structure-directing agent contained in the coarse dispersion is first reduced. begins to color, so when combining (a) when coloration is observed in the supernatant liquid generated in the sedimentation process, (c) after the re-dispersion process, use water with a high specific resistance value (high cost) is desirable.
  • the specific resistance in the (c) redispersion step after the m th time It is preferable to use water with a large value (high cost), for example, water with a specific resistance of 18 M ⁇ cm or more.
  • the coloration of the dispersion corresponds to the appearance of absorption based on silver nanoparticles around 405 nm by absorption spectrometry of the dispersion.
  • the supernatant liquid obtained in the (b) supernatant removing step can be used as a sample.
  • the amount of water used in the above (c) redispersion step is 25 to 400 parts by weight, preferably 30 to 300 parts by weight, relative to 1 part by weight of silver in the residual liquid containing the precipitated silver nanowires. It is preferably from 50 to 200 parts by mass. If it is less than 25 parts by mass, the concentration of the silver nanowires is too high, making it difficult to redisperse them uniformly. Labor is required.
  • the same precipitation solvent can be used in the n-time precipitation step (a), but a different precipitation solvent can be used for each number of times.
  • the amount of the precipitation solvent used in the nth precipitation step (a) is 50 parts by weight with respect to 100 parts by weight of the water used in the (n-1)th redispersion step (c) performed before that. to 500 parts by mass, more preferably 70 to 300 parts by mass.
  • the amount of the sedimentation solvent used in the first sedimentation step (a) is the same as the amount used in the n-th sedimentation step (a) when water is contained in the coarse dispersion prepared in the coarse dispersion preparation step. Equivalent amounts are preferred.
  • the precipitate containing the silver nanowires will settle by adding the precipitation solvent.
  • the amount of the precipitation solvent added is preferably 50 to 500 parts by mass, more preferably 70 to 300 parts by mass, per 100 parts by mass of the crude dispersion. If the coarse dispersion contains no water, it is preferred to use butyl acetate as the precipitating solvent.
  • the silver nanowire ratio is measured by the method described in Examples below.
  • the reprecipitation washing step may include steps other than steps (a), (b), and (c) within a range that does not impair the effects of the present invention.
  • Other steps include (c′) a redispersion step of adding water having a specific resistance of less than 3.3 M ⁇ cm to the remaining precipitate to redisperse the precipitate in water to obtain a redispersion liquid. be done.
  • a series of operations [(a) ⁇ (b) ⁇ (c′)] may be included within a range of preferably 10 times or less, but it is better not to include step (c′). This is preferable because it can reduce the number of times of a series of operations.
  • Silver concentration is determined using the Volhard method. About 1 g of the sample is weighed into a beaker, and 4 mL of nitric acid (1+1) and 20 mL of pure water are added. Cover the beaker with a watch glass and heat on a hot plate to 150° C. to dissolve the solids. After confirming the dissolution, the heating is stopped and the mixture is allowed to cool. The inner surface of the watch glass and the wall surface of the beaker are washed with pure water to make the liquid volume about 50 mL.
  • the silver concentration is calculated according to the following formula.
  • Silver concentration (% by mass) ⁇ (V x c) x 107.9/1000 ⁇ /m m: Weight of sample (g)
  • V Amount of ammonium thiocyanate aqueous solution consumed for titration up to the endpoint (mL)
  • c concentration of ammonium thiocyanate aqueous solution (0.01 mol/L)
  • Nitric acid (1+1), ammonium iron sulfate (III), and ammonium thiocyanate were all reagents manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.
  • Ammonium iron (III) sulfate (3% nitric acid) was prepared by mixing 5.17 g of ammonium iron (III) sulfate, 170 g of pure water and 2.00 g of nitric acid.
  • the 0.01 mol/L ammonium thiocyanate aqueous solution was prepared by adding pure water to 38.06 mg of ammonium thiocyanate to make the total amount 50 mL.
  • the silver nanowires/aqueous dispersion obtained in step (c) during each series of operations in the reprecipitation washing step was diluted with methanol 300 times by mass to dilute the silver nanowires.
  • a dispersion is made.
  • One drop of the silver nanowire dilute dispersion is dropped on a clean glass plate and dried on a hot plate at 90°C.
  • the glass plate is observed with a laser microscope (Keyence VK-X200) at a magnification of 3000 (measurement field: 260 ⁇ m ⁇ 200 ⁇ m) to count the number of silver nanowires and silver nanoparticles.
  • a ratio of silver nanowires in the dispersion (number of silver nanowires/(number of silver nanowires + number of silver nanoparticles)) is calculated.
  • Tap water was purified with a distilled water manufacturing apparatus RFD280NC (manufactured by ADVANTEC). As the specific resistance value, the value displayed on the monitor of the device was recorded. Distilled water and ultrapure water obtained by further purifying the distilled water can be produced by this apparatus.
  • Coarse dispersion liquid preparation step Synthesis example 1 ⁇ Production of coarse dispersion of silver nanowires> 667 g of propylene glycol (manufactured by AGC Co., Ltd.) was weighed into a 1 L plastic container, 22.5 g (0.13 mol) of silver nitrate (manufactured by Toyo Kagaku Kogyo Co., Ltd.) was added as a metal salt, and the mixture was stirred for 2 hours at room temperature under light shielding. A silver nitrate solution (second solution) was prepared.
  • Silver nanowires were synthesized by connecting the previously prepared silver nitrate solution (second solution) to a metering pump and dropping it into the first solution at a temperature of 150° C. over 2.5 hours. After completion of the dropwise addition, heating and stirring was continued for 30 minutes to complete the reaction.
  • the silver concentration of the obtained silver nanowire coarse dispersion was measured using the titration method (Volhardt method), it was 0.4% by mass.
  • the shape of the contained silver nanowires was observed at arbitrarily 100 points using an SEM (JSM-7000F manufactured by JEOL Ltd.), and when measured, the average diameter was 24 nm and the average length was 13 ⁇ m.
  • the resulting coarse dispersion of silver nanowires was directly used as a coarse dispersion in the reprecipitation cleaning step in each of the following examples and comparative examples.
  • Example 3 As a good solvent (water) added in step (c), 24 g of ultrapure water with a specific resistance value of 18.2 M ⁇ cm was added for the first three times, and the remaining times until the silver nanowire ratio reached >90%. Silver nanowires were purified in the same manner as in Example 1, except that 24 g of ion-exchanged water A having an average specific resistance of 10 M ⁇ cm (3.3 to 15 M ⁇ cm) was used. As in Example 1, the number of series of operations (steps (a), (b), and (c)) until the silver nanowire ratio reached >90% was recorded as the number of reprecipitation washings. The results are shown in Table 1.
  • Example 4 As a good solvent (water) added in step (c), 24 g of ion-exchanged water A with an average specific resistance value of 10 M ⁇ cm (3.3 to 15 M ⁇ cm) is used for the first three times, and the silver nanowire ratio is >90%. Silver nanowires were purified in the same manner as in Example 1 except that 24 g of ultrapure water with a specific resistance of 18.2 M ⁇ cm was used for the remaining number of times until reaching the target. As in Example 1, the number of series of operations (steps (a), (b), and (c)) until the silver nanowire ratio reached >90% was recorded as the number of reprecipitation washings. The results are shown in Table 1.
  • Example 5 As a good solvent (water) to be added in step (c), 0.1 mg of sodium chloride (manufactured by Junsei Chemical Co., Ltd.) dissolved in 1500 g of ultrapure water with a specific resistance of 18.2 M ⁇ cm has a specific resistance of 5.0 M ⁇ cm. Silver nanowires were purified in the same manner as in Example 1 except that 24 g of water was used. As in Example 1, the number of series of operations (steps (a), (b), and (c)) until the silver nanowire ratio reached >90% was recorded as the number of reprecipitation washings. The results are shown in Table 1.
  • step (c′) a redispersion step of adding water having a specific resistance of less than 3.3 M ⁇ cm to the remaining precipitate to redisperse the precipitate in water to obtain a redispersion liquid.
  • water water
  • silver nanoparticles were prepared in the same manner as in Example 1 except that 24 g of ion-exchanged water B with an average specific resistance of 2.0 M ⁇ cm (1.5 to 2.5 M ⁇ cm) was used. Refined wire. The reprecipitation washing was repeated nine times, but the silver nanowire ratio did not reach >90%. The results are shown in Table 1.
  • step (c′) a redispersion step of adding water having a specific resistance of less than 3.3 M ⁇ cm to the remaining precipitate to redisperse the precipitate in water to obtain a redispersion liquid.
  • the silver nanowires were purified in the same manner as in Example 1, except that 24 g of tap water having a specific resistance of 0.005 M ⁇ cm was used as the good solvent (water) to be added. The reprecipitation washing was repeated nine times, but the silver nanowire ratio did not reach >90%. The results are shown in Table 1.
  • step (c′) a redispersion step of adding water having a specific resistance of less than 3.3 M ⁇ cm to the remaining precipitate to redisperse the precipitate in water to obtain a redispersion liquid.
  • the silver nanowires were purified in the same manner as in Example 1, except that 24 g of distilled water with a specific resistance of 0.1 M ⁇ cm was used as the good solvent (water) to be added. The reprecipitation washing was repeated nine times, but the silver nanowire ratio did not reach >90%. The results are shown in Table 1.
  • Comparative example 4 After the implementation of Comparative Example 1, the good solvent (water) added in step (c) was washed again by reprecipitation using deionized water A with an average specific resistance value of 10 M ⁇ cm (3.3 to 15 M ⁇ cm) for 10 times. repeated times. The results are shown in Table 1.
  • step (c′) a redispersion step of adding water having a specific resistance of less than 3.3 M ⁇ cm to the remaining precipitate to redisperse the precipitate in water to obtain a redispersion liquid.
  • water As a good solvent (water) to be added, 24 g of water with a specific resistance value of 0.8 M ⁇ cm in which 0.9 mg of sodium chloride (manufactured by Junsei Chemical Co., Ltd.) is dissolved in 1500 g of ultrapure water of 18.2 M ⁇ cm was used.
  • Silver nanowires were purified in the same manner as in Example 1 except for the above. The reprecipitation washing was repeated nine times, but the silver nanowire ratio did not reach >90%. The results are shown in Table 1.
  • Example 1 using water with a specific resistance value of 3.3 M ⁇ cm or more in the step (c), the silver nanowire ratio reached >90%, whereas the specific resistance value was less than 3.3 M ⁇ cm.
  • Comparative Examples 1 to 3 and 5 using water the silver nanowire ratio did not reach 90% with the same number of washings, and it was confirmed that by-product nanoparticles could not be removed. Regardless of the presence or absence of purification of water and the purification method, it can be said that the nanoparticle removal efficiency changes depending on the specific resistance value.
  • Example 2 which uses ultrapure water with particularly high purity, the silver nanowire ratio reaches >90% with fewer washings than in Example 1, which uses only normal ion-exchanged water.
  • Example 3 when comparing Example 3 and Example 4 in which ion-exchanged water and ultrapure water are combined, it is found that the structure-directing agent is the threshold value rather than using ultrapure water in the first half, in which a large amount of the structure-directing agent remains and the silver nanoparticles are difficult to remove. It was possible to efficiently remove the nanoparticles with a smaller number of washings in the second half when the nanoparticles were more easily dispersed in the supernatant liquid. In Example 2 and Example 4, the cleaning efficiency was substantially the same.
  • step (c′) was performed instead of step (c) (repeating a series of operations of step (a) ⁇ step (b) ⁇ step (c′)), and the silver nanowire ratio peaked out.
  • Reprecipitation washing a series of operations of step (a) ⁇ step (b) ⁇ step (c)
  • the silver nanowire ratio improved, it did not reach 90%. From this, it can be said that it is effective to use high-purity water with a large specific resistance value throughout the re-precipitation washing (in all re-dispersion steps).

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Abstract

Le problème décrit par la présente invention est de fournir un procédé de fabrication de nanofil d'argent par lequel des nanoparticules d'argent peuvent être efficacement éliminées d'un liquide de dispersion grossière contenant des nanofils d'argent et les nanoparticules d'argent. À cet effet, l'invention porte sur un procédé de fabrication de nanofil d'argent caractérisé en ce qu'il comprend une étape de préparation de liquide de dispersion grossière destinée à préparer un liquide de dispersion grossière contenant des nanofils d'argent et des nanoparticules d'argent et une étape de reprécipitation/nettoyage destinée à affiner les nanofils d'argent dans le liquide de dispersion grossier au moyen d'un procédé de reprécipitation. Au cours de l'étape de reprécipitation/nettoyage, on répète plusieurs fois une série d'opérations, qui comprennent (a) une étape de précipitation pour amener des précipités contenant des nanofils d'argent à précipiter par ajout d'un solvant de précipitation au liquide de dispersion grossier ou à un liquide de redispersion décrit ci-dessous, (b) une étape d'élimination de surnageant pour éliminer un surnageant contenant au moins une partie des nanoparticules d'argent formées par la précipitation des précipités, et (c) une étape de redispersion pour obtenir un liquide de redispersion par redispersion des précipités dans l'eau par ajout d'eau ayant une valeur de résistance spécifique de 3,3 MΩ · cm ou plus aux précipités restants.
PCT/JP2022/009791 2021-03-31 2022-03-07 Procédé de fabrication d'un nanofil d'argent WO2022209613A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102211205A (zh) * 2011-05-18 2011-10-12 山东大学 一种制备系列高纯度银纳米材料的方法
KR20140103601A (ko) * 2013-02-18 2014-08-27 주식회사 에이든 은 나노와이어 제조방법
JP5936759B1 (ja) * 2015-09-30 2016-06-22 マイクロ波化学株式会社 銀ナノワイヤの製造方法
JP2017020104A (ja) * 2015-06-12 2017-01-26 ダウ グローバル テクノロジーズ エルエルシー 濾過した銀ナノワイヤを製造するための水熱法
CN111715877A (zh) * 2020-05-22 2020-09-29 深圳市华科创智技术有限公司 一种纳米银线的纯化方法
JP2020190025A (ja) * 2019-05-24 2020-11-26 Ｄｏｗａエレクトロニクス株式会社 銀ナノワイヤの製造法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102211205A (zh) * 2011-05-18 2011-10-12 山东大学 一种制备系列高纯度银纳米材料的方法
KR20140103601A (ko) * 2013-02-18 2014-08-27 주식회사 에이든 은 나노와이어 제조방법
JP2017020104A (ja) * 2015-06-12 2017-01-26 ダウ グローバル テクノロジーズ エルエルシー 濾過した銀ナノワイヤを製造するための水熱法
JP5936759B1 (ja) * 2015-09-30 2016-06-22 マイクロ波化学株式会社 銀ナノワイヤの製造方法
JP2020190025A (ja) * 2019-05-24 2020-11-26 Ｄｏｗａエレクトロニクス株式会社 銀ナノワイヤの製造法
CN111715877A (zh) * 2020-05-22 2020-09-29 深圳市华科创智技术有限公司 一种纳米银线的纯化方法

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