WO2019059296A1 - Manufacturing method for silver nanowire, silver nanowire, silver nanowire ink, and transparent conductive film - Google Patents

Manufacturing method for silver nanowire, silver nanowire, silver nanowire ink, and transparent conductive film Download PDF

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WO2019059296A1
WO2019059296A1 PCT/JP2018/034864 JP2018034864W WO2019059296A1 WO 2019059296 A1 WO2019059296 A1 WO 2019059296A1 JP 2018034864 W JP2018034864 W JP 2018034864W WO 2019059296 A1 WO2019059296 A1 WO 2019059296A1
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silver
silver nanowire
silver nanowires
alcohol solvent
average
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PCT/JP2018/034864
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French (fr)
Japanese (ja)
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王高 佐藤
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Ｄｏｗａエレクトロニクス株式会社
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Priority to CN201880051095.6A priority Critical patent/CN111032256A/en
Publication of WO2019059296A1 publication Critical patent/WO2019059296A1/en

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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
    • 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
    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
    • H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports

Definitions

  • the present invention relates to a method for producing silver nanowires useful as a conductive material (filler) of a transparent conductive film.
  • the present invention also relates to a silver nanowire, a silver nanowire ink, and a transparent conductive film obtained by the production method.
  • nanowire (s) a fine metal wire having a thickness of about 200 nm or less.
  • Silver nanowires are considered promising as a conductive material for imparting conductivity to transparent substrates.
  • a transparent substrate such as glass, PET (polyethylene terephthalate), PC (polycarbonate), etc.
  • the liquid component is removed by evaporation or the like, the silver nanowires are on the substrate Since a conductive network is formed by contacting each other, a transparent conductive film can be realized.
  • a transparent conductive film used for a touch panel or the like of an electronic device is required to have clear visibility with little haze, in addition to good conductivity.
  • a silver compound is dissolved in a polyol solvent such as ethylene glycol, and in the presence of a halogen compound and an organic protective agent, a linear shape is obtained using the reducing power of the solvent polyol.
  • a method of precipitating metallic silver hereinafter referred to as "alcohol solvent reduction method"
  • organic protective agent PVP (polyvinyl pyrrolidone) has generally been widely used. PVP is a suitable organic protective agent for depositing thin and long silver nanowires.
  • the molecules of the organic protective agent used in the alcohol solvent reduction method adsorb on the surface of the silver nanowire after synthesis, and become a factor governing the dispersibility of the silver nanowire in the liquid medium.
  • Silver nanowires adsorbed with PVP exhibit good dispersibility in water.
  • an organic solvent for example, alcohol
  • PVP is not necessarily a satisfactory organic protective agent.
  • Patent Document 1 is a copolymer having a polymerization composition of vinyl pyrrolidone and Diallyldimethylammonium salt monomer
  • Patent Document 2 is a copolymer of vinyl pyrrolidone and an acrylate based or methacrylate based monomer
  • Patent Document 3 is Vinyl. Copolymers of pyrrolidone and maleimide based monomers are disclosed, respectively. In the alcohol solvent reduction method using these polymers as organic protective agents, it is possible to synthesize thin and long silver nanowires by optimizing the synthesis conditions, as well as or more than using PVP. is there.
  • the silver nanowires used as the conductive material of the transparent conductive coating film have a thin and long form from the viewpoint of achieving both conductivity and visibility at a high level.
  • the present invention is intended to provide a highly effective technique for producing a particularly long wire stably when synthesizing a thin silver nanowire by an alcohol solvent reduction method.
  • the above object is achieved in the alcohol solvent reduction method by advancing the precipitation reaction of silver in an environment where a predetermined concentration of organic acid ester is present in the solvent.
  • the following invention is disclosed in the present specification.
  • a method of producing a silver nanowire the process of reducing and depositing silver in the form of a wire in an alcohol solvent in which a silver compound and an organic protective agent are dissolved, Using a polymer having a vinyl pyrrolidone structural unit as the organic protective agent, A state in which an organic acid ester is dissolved at a concentration of 0.1 to 20.0 mmol / L in the alcohol solvent, and the reduction deposition proceeds in the liquid;
  • a M L M / D M (1)
  • L M is a value representing the average length in nm
  • D M is a value representing the average diameter in nm.
  • the polymer is vinyl pyrrolidone, diallyl dimethyl ammonium salt, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, N-methyl maleimide, N-ethyl maleimide, N-propyl [1] to [3] having a polymerization composition with one or more monomers selected from maleimide, N-tert-butyl maleimide, 2-dimethylaminoethyl methacrylate, and 2-diethylaminoethyl methacrylate
  • the manufacturing method of the silver nanowire in any one of.
  • the average length, average diameter and average aspect ratio of silver nanowires follow the definitions below.
  • Average length L M The trace length from one end of one silver nanowire to the other end of a silver nanowire is defined as the length of the wire on an image observed by a field emission scanning electron microscope (FE-SEM). A value obtained by averaging the lengths of the individual silver nanowires present on the microscopic image is defined as an average length L M. In order to calculate the average length, the total number of wires to be measured is set to 100 or more. Here, the average length in the stage in which the silver nanowires recovered from the solution after the reduction reaction were washed (stage before being supplied to the purification step such as cross flow filtration) is evaluated.
  • FIG. 4 exemplifies a TEM bright-field observation image (hereinafter referred to as “TEM image”) of silver nanowires according to the present invention.
  • TEM image TEM bright-field observation image
  • Each wire can be considered to have a substantially even thickness over its entire length. Therefore, thickness measurement can be performed by selecting a portion that does not overlap other wires.
  • the diameters of all the wires except for the wires completely overlapping with other wires and whose diameter is difficult to measure are measured.
  • the operation is performed on a plurality of randomly selected fields of view, the diameters of a total of 100 or more different silver nanowires are determined, the average value of the diameters of the individual silver nanowires is calculated, and the value is defined as the average diameter D M.
  • the average aspect ratio AM is calculated by substituting the above average diameter D M and the average length L M into the following equation (1). However, it is assumed that D M and L M to be substituted into the equation (1) are both values expressed in nm.
  • a M L M / D M (1)
  • the present invention it is possible to stably synthesize long silver nanowires having an average length of, for example, 15 nm or more and an average aspect ratio of 600 or more, for thin silver nanowires having an average diameter of, for example, 35 nm or less. Since long silver nanowires with an average length as described above can be obtained at the stage of completion of washing after synthesis, if the purification operation to adjust the wire length distribution by cross flow filtration etc. is performed thereafter, the average length will be Longer, high aspect ratio silver nanowires can be manufactured with high yield. When it is used as a conductive material of a transparent conductive film, a transparent conductive film excellent in visibility with less haze can be realized while maintaining high conductivity.
  • the polymer molecule of the organic protective agent In order to deposit metallic silver in the form of a wire by alcohol solvent reduction method, it is necessary for the polymer molecule of the organic protective agent to be selectively adsorbed on the ⁇ 100 ⁇ face of the nucleus crystal that is considered to be multiple twins of silver. It is. Thereby, the growth of the ⁇ 100 ⁇ plane is suppressed, the ⁇ 111 ⁇ plane which is the closest surface of the silver crystal is preferentially grown, and a linear structure of metallic silver is formed.
  • the selective adsorptivity of polymer molecules is believed to be caused by the interaction between the surface potential of the polymer molecules and the surface potential of the silver crystal face.
  • Homopolymers (PVP) and copolymers having vinyl pyrrolidone structural units are known as polymers excellent in selective adsorption to the silver crystal ⁇ 100 ⁇ plane.
  • the structural formula of a vinyl pyrrolidone structural unit is shown in FIG.
  • the inventors have variously studied a method for improving the average length of the synthesized wire particularly when synthesizing a thin silver nanowire using a polymer having a vinyl pyrrolidone structural unit as an organic protective agent.
  • an organic acid ester is extremely effective in addition to conventionally used additives such as halides.
  • the organic acid ester acts to clean the ⁇ 111 ⁇ crystal face on which silver preferentially precipitates when synthesizing silver nanowires by the alcohol solvent reduction method, ie, an organic protective agent molecule to the ⁇ 111 ⁇ crystal face It is thought that it has the effect of suppressing the adsorption of and activating the exposed ⁇ 111 ⁇ crystal face to promote the deposition of new silver.
  • the action to activate the ⁇ 111 ⁇ crystal face is mainly borne by the conventional additives such as halides, but it is presumed that the organic acid ester also acts in a similar manner. If an organic acid ester is present in addition to the halogen in the vicinity of the metallic silver linear structure already deposited, the above-mentioned cleaning action is enhanced, and the surface in the thickness direction of the linear structure ( ⁇ 100 ⁇ crystal plane). The relative ease of deposition on the exposed surface in the longitudinal direction ( ⁇ 111 ⁇ crystal plane) relative to the ease of deposition of silver on silver) is further enhanced, resulting in a silver nanowire with a large average aspect ratio It is considered that the synthesis of
  • the concentration of the organic acid ester is increased, the effect of improving the average length of the silver nanowires is saturated.
  • the concentration of the organic acid ester in the solvent may be set in the range of 20.0 mmol / L (20.0 ⁇ 10 ⁇ 3 mol / L) or less, and 15.0 mmol / L (15.0 ⁇ 10 ⁇ 3 mol / L) ) You may manage as follows.
  • the amount ratio of the organic acid ester in the solution is 0 per 1 mol of the polymer having a vinylpyrrolidone structural unit, which is an organic protective agent, in terms of the quantitative ratio to the organic protective agent present in the alcohol solvent at the time of the reductive deposition reaction. It is preferable to adjust in the range of .001 to 0.3 mol. Also, in terms of quantitative ratio to silver, adjust the amount of the organic acid ester in the liquid to be in the range of 0.001 to 0.5 mol at the time of reaction disclosure with respect to 1 mol of the total amount of silver used for the reaction. Is preferred.
  • organic acid ester examples include diethyl adipate (C 10 H 18 O 4 ), triethyl acetyl citrate (C 14 H 22 O 8 ), isoamyl benzoate (C 12 H 16 O 2 ), ethyl benzoate (C 9 H 10 O 2 ), ethyl isovalerate (C 7 H 14 O 2 ), ethyl formate (C 3 H 6 O 2 ), butyl formate (C 5 H 10 O 2 ), tributyl citrate (C 18 H 32) O 7 ), diethyl oxalate (C 6 H 10 O 4 ), diethyl tartrate (C 8 H 14 O 6 ), ethyl stearate (C 20 H 40 O 2 ), ethyl lactate (C 5 H 10 O 3 ), diethyl phthalate (C 12 H 14 O 4) , ethyl propionate (C 5 H 10 O 2) , diisopropyl maleate (C
  • PVP polyvinylpyrrolidone
  • a copolymer of vinylpyrrolidone and a hydrophilic monomer is a suitable target.
  • the latter copolymers include, for example, vinyl pyrrolidone and diallyl dimethyl ammonium salt, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, N-methyl maleimide, N-ethyl maleimide, N- Examples include copolymers having a polymerization composition with one or more monomers selected from propyl maleimide and N-tert-butyl maleimide.
  • the polymerization composition of the copolymer is preferably 0.1 to 10% by weight of monomers other than vinyl pyrrolidone, with the balance being vinyl pyrrolidone.
  • the weight average molecular weight Mw of the polymer used for the organic protective agent is preferably in the range of 30,000 to 300,000, and more preferably in the range of 30,000 to 150,000. Mw can be determined by GPC (gel permeation chromatography).
  • acetic acid ester may be used as an organic solvent in purifying the polymer formed by polymerization. In that case, acetic acid ester is mixed as an impurity in the polymer powder product.
  • acetic acid ester in order to adjust the concentration of the organic acid ester in the alcohol solvent to the above-mentioned predetermined range, it is necessary to compensate a part of the organic acid ester introduced into the solvent by the acetic acid ester present in the polymer powder.
  • polymer powder having an acetic acid ester content of, for example, less than 0.002 mol can be used as a source of the organic protective agent with respect to 1 mol of the polymer having a vinyl pyrrolidone structural unit.
  • the amount of acetic acid ester introduced from the polymer powder into the alcohol solvent is small, it can be ignored in the calculation of the concentration of the organic acid ester in the alcohol solvent.
  • the amount of acetic acid ester in the polymer powder can be determined from the NMR (nuclear magnetic resonance) spectrum of the polymer powder.
  • the silver nanowire is preferably as thin and long as possible from the viewpoint of forming a transparent conductive coating film excellent in conductivity and visibility.
  • an object having an average length of 15 ⁇ m or more, an average diameter of 35 nm or less, and an average aspect ratio of 600 or more according to the equation (1) is suitable. It is more preferable that the average length is 15 ⁇ m or more and the average diameter is 33 nm or less. It is more preferable that the average length is 15 ⁇ m or more and the average diameter is 30 nm or less.
  • silver nanowires having a long average length and a large average aspect ratio can be obtained in the synthesis stage, so that the length distribution can be efficiently adjusted at a high yield, for example, by cross flow purification in the subsequent steps. Can.
  • silver nitrate, silver acetate, silver oxide, silver chloride and the like can be mentioned, but silver nitrate (AgNO 3 ) is easy to use in consideration of the solubility in a solvent and the cost.
  • silver compound the organic protective agent and the organic acid ester
  • reduction deposition may be allowed to proceed in an alcohol solvent in which an alkali metal hydroxide or aluminum salt is dissolved.
  • an alcohol solvent to which an organic acid ester is added can be applied.
  • Comparative Example 1 (Organic protective agent) A copolymer powder was prepared by dissolving 1-vinyldipyrrolidone and diallyldimethylammonium nitrate in a solvent, methyl isobutyl ketone, as a solvent, and copolymerizing by adding a polymerization initiator.
  • the 1 H NMR spectrum of the copolymer powder was measured by nuclear magnetic resonance spectroscopy (NMR) with JNM-LA400 (400 MHz) manufactured by JEOL Ltd., and the components contained in the powder were examined.
  • NMR nuclear magnetic resonance spectroscopy
  • JNM-LA400 400 MHz
  • MIBK MIBK
  • ethyl acetate uses the integral value of the peak around 4.1 ppm
  • TBME uses the integral value of the peak around 1.2 ppm
  • MIBK uses the integral value of the peak around 0.9 ppm
  • the residual VP amount was determined by the following equation (2).
  • VP R (mol%) [2 ⁇ (I 1 + I 2 ) / (3 ⁇ I 3 )] ⁇ 100 (2)
  • I 3 is the integral value of the peak (3.0-3.4ppm) derived from the methylene protons adjacent to the N atom of the polymer.
  • the weight average molecular weight Mw of the above copolymer was determined by GPC (gel permeation chromatography) under the following conditions.
  • ⁇ Device HLC-8320GPC EcoSEC (made by Tosoh Corporation)
  • Column TSKgel GMPWXL ( ⁇ 2) + G2500PWXL
  • Flow rate 1.0 mL / min
  • Temperature 40 ° C
  • Injection volume 200 ⁇ L -Multi-angle light scattering detector: DAWN HELEOS II (manufactured by Wyatt Technology) Refractive index (RI) detector: Optilab T-rEX (manufactured by Wyatt Technology)
  • the weight average molecular weight Mw was 84,000.
  • the above solution A is put in a reaction vessel and heated from normal temperature to 95 ° C. with stirring at a rotational speed of 250 rpm, and then the whole solution B is added to solution A using a tube pump from two addition ports. Added over a minute.
  • 4 g of a propylene glycol solution is added using a tube pump in order to wash out the inside of the tube to which solution B adheres, and then it is kept stirring at 95 ° C. for 3.5 hours. Cooled to 0 C over 2.0 hours and held at 85 0 C for 19 hours. Then, the silver nanowire was synthesize
  • the dispersion In measuring the length of silver nanowires, the dispersion is placed on an observation table for SEM, water is volatilized on the observation table, and then a field emission scanning electron microscope (manufactured by Hitachi High-Technologies Corporation; S-4700) The observation was performed at an acceleration voltage of 3 kV and a magnification of 1,500. For three or more randomly selected fields of view, the average length was measured according to the above definition for all wires whose full length can be confirmed in the field of view. In the diameter measurement, the dispersion was placed on an observation table for TEM, and bright field images were observed at an acceleration voltage of 100 kV and a magnification of 40,000 with a transmission electron microscope (manufactured by JEOL Ltd .; JEM-1011).
  • the observation image is taken, and the original image taken to accurately measure the diameter is enlarged to twice the size, and then using software (Motic Image Plus 2.1 S), the average diameter is determined according to the above definition. It was measured.
  • the average aspect ratio was determined by substituting the values of the average length and the average diameter into the equation (1).
  • the average diameter of the silver nanowires was 35.8 nm, and the average length was 14.1 ⁇ m.
  • the average aspect ratio was 14100 (nm) /35.8 (nm) ⁇ 394.
  • Table 1 The results are summarized in Table 1 together with other examples and comparative examples.
  • Example 1 The same as in Comparative Example 1, except that, in addition to each of the substances mixed in Comparative Example 1, 0.0052 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 0.119 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 32.6 nm, and the average length was 19.6 ⁇ m.
  • the average aspect ratio was 19600 (nm) /32.6 (nm) ⁇ 601.
  • Example 2 The same as in Comparative Example 1, except that, in addition to the respective substances mixed in Comparative Example 1, 0.0131 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 0.298 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 32.1 nm, and the average length was 19.6 ⁇ m.
  • the average aspect ratio was 19600 (nm) /32.1 (nm) 611 611.
  • Example 3 The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0263 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (ie, the initiation of the addition of solution B) is 0.598 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 28.5 nm, and the average length was 21.8 ⁇ m.
  • the average aspect ratio was 21800 (nm) /28.5 (nm) 765 765.
  • Example 4 The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0798 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 28.4 nm, and the average length was 23.3 ⁇ m.
  • the average aspect ratio was 23300 (nm) /28.4 (nm) ⁇ 820.
  • Example 5 The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.1344 g of ethyl acetate was further mixed and dissolved as the solution A when synthesizing silver nanowires. The experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 3.051 mmol / L.
  • the average diameter of the silver nanowire obtained under this condition was 28.8 nm, and the average length was 23.9 ⁇ m.
  • the average aspect ratio was 23900 (nm) /28.8 (nm) 830 830.
  • Example 6 The same as in Comparative Example 1, except that 0.2759 g of ethyl acetate was further mixed and dissolved as solution A in addition to the respective materials mixed in Comparative Example 1 when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 6.263 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 28.5 nm, and the average length was 22.2 ⁇ m.
  • the average aspect ratio was 22200 (nm) /28.5 (nm) 779 779.
  • Example 7 The same method as Comparative Example 1 was used except that, in addition to the respective materials mixed in Comparative Example 1, 0.3346 g of ethyl acetate was further mixed and dissolved as a solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (ie, the initiation of the addition of solution B) is 7.595 mmol / L.
  • the average diameter of the silver nanowire obtained under this condition was 28.7 nm, and the average length was 22.1 ⁇ m.
  • the average aspect ratio was 22100 (nm) /28.7 (nm) 770 770.
  • Example 8 The same as in Comparative Example 1, except that, in addition to each of the substances mixed in Comparative Example 1, 0.4250 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 9.648 mmol / L.
  • the average diameter of the silver nanowire obtained under this condition was 29.4 nm, and the average length was 23.0 ⁇ m.
  • the average aspect ratio was 23000 (nm) /29.4 (nm) 782 782.
  • Example 9 When silver nanowires were synthesized, the same solution as in Comparative Example 1 was used except that a solution obtained by mixing and dissolving 0.5825 g of ethyl acetate in addition to the respective materials mixed in Comparative Example 1 was used. The experiment was conducted under the conditions.
  • the ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 13.221 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 29.2 nm, and the average length was 24.5 ⁇ m.
  • the average aspect ratio was 24500 (nm) /29.2 (nm) ⁇ 839.
  • Example 10 The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.1052 g of methyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the methyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 27.7 nm, and the average length was 20.3 ⁇ m.
  • the average aspect ratio was 20300 (nm) /27.7 (nm) 733 733.
  • Example 11 The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0671 g of propyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the propyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L.
  • the average diameter of the silver nanowire obtained under this condition was 28.2 nm, and the average length was 18.2 ⁇ m.
  • the average aspect ratio was 18200 (nm) /28.2 (nm) 645645.
  • Example 12 The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0925 g of butyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires.
  • the experiment was conducted under the conditions.
  • the butyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L.
  • the average diameter of silver nanowires obtained under this condition was 26.6 nm, and the average length was 17.7 ⁇ m.
  • the average aspect ratio was 17700 (nm) /26.6 (nm) ⁇ 665.
  • the presence of the organic acid ester in the alcohol solvent at the time of silver nanowire synthesis can significantly improve the average length of the synthesized wire, and accordingly the average aspect ratio of the wire improves.
  • FIGS. 2 and 3 respectively show SEM and TEM photographs of the silver nanowire obtained in Comparative Example 1
  • FIGS. 4 and 5 show SEM and TEM photographs of the silver nanowire obtained in Example 3 respectively.

Abstract

[Problem] To stably generate, in particular, a wire with a long average length and a large average aspect, when a thin silver nanowire is synthesized by an alcohol solvent reduction method. [Solution] A manufacturing method for a silver nanowire, comprising a step in which silver is formed into a wire shape by deposition reduction in an alcohol solvent in which a silver compound and an organic protecting agent have been dissolved, wherein the manufacturing method for a silver nanowire is characterized in that a polymer with a vinyl pyrrolidine structural unit is used as the organic protecting agent, an organic acid ester is dissolved in the alcohol solvent to a concentration of 0.1–20.0 mmol/L, and the deposition reduction is made to proceed in this solution.

Description

銀ナノワイヤの製造法並びに銀ナノワイヤ、銀ナノワイヤインクおよび透明導電膜Method for producing silver nanowire and silver nanowire, silver nanowire ink and transparent conductive film
　本発明は、透明導電膜の導電素材（フィラー）として有用な銀ナノワイヤの製造方法に関する。また、その製造方法によって得られる銀ナノワイヤ、銀ナノワイヤインクおよび透明導電膜に関する。 The present invention relates to a method for producing silver nanowires useful as a conductive material (filler) of a transparent conductive film. The present invention also relates to a silver nanowire, a silver nanowire ink, and a transparent conductive film obtained by the production method.
　本明細書では、太さが２００ｎｍ程度以下の微細な金属ワイヤを「ナノワイヤ（ｎａｎｏｗｉｒｅ（ｓ）」と呼ぶ。 In this specification, a fine metal wire having a thickness of about 200 nm or less is referred to as "nanowire (s)".
　銀ナノワイヤは、透明基材に導電性を付与するための導電素材として有望視されている。銀ナノワイヤを含有する液（銀ナノワイヤインク）をガラス、ＰＥＴ（ポリエチレンテレフタレート）、ＰＣ（ポリカーボネート）などの透明基材に塗布したのち、液状成分を蒸発等により除去すると、銀ナノワイヤは当該基材上で互いに接触し合うことにより導電ネットワークを形成するので、透明導電膜を実現することができる。 Silver nanowires are considered promising as a conductive material for imparting conductivity to transparent substrates. After the liquid containing silver nanowires (silver nanowire ink) is applied to a transparent substrate such as glass, PET (polyethylene terephthalate), PC (polycarbonate), etc., the liquid component is removed by evaporation or the like, the silver nanowires are on the substrate Since a conductive network is formed by contacting each other, a transparent conductive film can be realized.
　電子機器のタッチパネル等に使用される透明導電膜には、導電性が良好であることに加え、ヘイズの少ないクリアな視認性が要求される。銀ナノワイヤを導電素材とする透明導電膜において導電性と視認性を高いレベルで両立させるためには、できるだけ細く、かつ長い銀ナノワイヤを適用することが有利となる。 A transparent conductive film used for a touch panel or the like of an electronic device is required to have clear visibility with little haze, in addition to good conductivity. In order to achieve both conductivity and visibility at a high level in a transparent conductive film using silver nanowires as a conductive material, it is advantageous to apply silver nanowires that are as thin and long as possible.
　従来、銀ナノワイヤの合成法として、例えば、エチレングリコール等のポリオール溶媒に銀化合物を溶解させ、ハロゲン化合物と有機保護剤の存在下において、溶媒であるポリオールの還元力を利用して線状形状の金属銀を析出させる手法（以下、「アルコール溶媒還元法」と言う。）が知られている。その有機保護剤として、従来一般的にＰＶＰ（ポリビニルピロリドン）が多用されてきた。ＰＶＰは細く長い銀ナノワイヤを析出させる上で好適な有機保護剤である。 Conventionally, as a synthesis method of silver nanowires, for example, a silver compound is dissolved in a polyol solvent such as ethylene glycol, and in the presence of a halogen compound and an organic protective agent, a linear shape is obtained using the reducing power of the solvent polyol. A method of precipitating metallic silver (hereinafter referred to as "alcohol solvent reduction method") is known. As the organic protective agent, PVP (polyvinyl pyrrolidone) has generally been widely used. PVP is a suitable organic protective agent for depositing thin and long silver nanowires.
　アルコール溶媒還元法で使用される有機保護剤の分子は、合成後の銀ナノワイヤ表面に吸着し、液状媒体中における銀ナノワイヤの分散性を支配する要因となる。ＰＶＰが吸着した銀ナノワイヤは、水に対して良好な分散性を呈する。しかし、ＰＥＴ等の基材に対する濡れ性を改善するためには、水と有機溶媒（例えばアルコール）との混合媒体を用いた銀ナノワイヤインクを適用することが有利となる。また、塗工設備によっては、非水系溶媒を用いた銀ナノワイヤインクを適用することが望ましい場合もある。ＰＶＰは、そのような混合媒体や非水系溶媒中での銀ナノワイヤの分散性を考慮した場合、必ずしも満足できる有機保護剤とは言えない。最近では、水以外の液状媒体中での銀ナノワイヤの分散性を改善することができる有機保護剤も種々開発されている。例えば、特許文献１にはビニルピロリドンとジアリルジメチルアンモニウム（Ｄｉａｌｌｙｌｄｉｍｅｔｈｙｌａｍｍｏｎｉｕｍ）塩モノマーとの重合組成を有するコポリマー、特許文献２にはビニルピロリドンとアクリレート系またはメタクリレート系モノマーとのコポリマー、特許文献３にはビニルピロリドンとマレイミド系モノマーとのコポリマーがそれぞれ開示されている。これらのポリマーを有機保護剤に用いたアルコール溶媒還元法では、合成条件を適正化することによって、ＰＶＰを用いた場合と同程度あるいはそれ以上に、細くて長い銀ナノワイヤを合成することが可能である。 The molecules of the organic protective agent used in the alcohol solvent reduction method adsorb on the surface of the silver nanowire after synthesis, and become a factor governing the dispersibility of the silver nanowire in the liquid medium. Silver nanowires adsorbed with PVP exhibit good dispersibility in water. However, in order to improve the wettability to a substrate such as PET, it is advantageous to apply a silver nanowire ink using a mixed medium of water and an organic solvent (for example, alcohol). In addition, depending on the coating equipment, it may be desirable to apply a silver nanowire ink using a non-aqueous solvent. When considering the dispersibility of silver nanowires in such mixed media and non-aqueous solvents, PVP is not necessarily a satisfactory organic protective agent. Recently, various organic protective agents have been developed which can improve the dispersibility of silver nanowires in liquid media other than water. For example, Patent Document 1 is a copolymer having a polymerization composition of vinyl pyrrolidone and Diallyldimethylammonium salt monomer, Patent Document 2 is a copolymer of vinyl pyrrolidone and an acrylate based or methacrylate based monomer, and Patent Document 3 is Vinyl. Copolymers of pyrrolidone and maleimide based monomers are disclosed, respectively. In the alcohol solvent reduction method using these polymers as organic protective agents, it is possible to synthesize thin and long silver nanowires by optimizing the synthesis conditions, as well as or more than using PVP. is there.
特開２０１５－１８０７７２号公報JP, 2015-180772, A 特開２０１７－７８２０７号公報JP, 2017-78207, A 特開２０１６－１３５９１９号公報JP, 2016-135919, A
　上述のように、透明導電塗膜の導電素材として使用する銀ナノワイヤは、導電性と視認性を高レベルで両立させる観点から、細くて長い形態であることが有利となる。本発明は、アルコール溶媒還元法で細い銀ナノワイヤを合成する際に、特に長いワイヤを安定して生成させる効果の高い技術を提供しようというものである。 As described above, it is advantageous that the silver nanowires used as the conductive material of the transparent conductive coating film have a thin and long form from the viewpoint of achieving both conductivity and visibility at a high level. The present invention is intended to provide a highly effective technique for producing a particularly long wire stably when synthesizing a thin silver nanowire by an alcohol solvent reduction method.
　上記目的は、アルコール溶媒還元法において、所定濃度の有機酸エステルが溶媒中に存在する環境下で銀の析出反応を進行させることによって達成される。本明細書では以下の発明を開示する。 The above object is achieved in the alcohol solvent reduction method by advancing the precipitation reaction of silver in an environment where a predetermined concentration of organic acid ester is present in the solvent. The following invention is disclosed in the present specification.
　［１］銀化合物、有機保護剤が溶解しているアルコール溶媒中で、銀をワイヤ状に還元析出させる工程を有する銀ナノワイヤの製造法において、
　前記有機保護剤としてビニルピロリドン構造単位を持つポリマーを使用すること、
　前記アルコール溶媒中に有機酸エステルが０.１～２０.０ｍｍｏｌ／Ｌの濃度で溶解している状態とし、その液中で前記還元析出を進行させること、
を特徴とする銀ナノワイヤの製造法。
　［２］平均長さ１５μｍ以上、平均直径３５ｎｍ以下、かつ下記（１）式で定義される平均アスペクト比ＡＭが６００以上である銀ナノワイヤを還元析出させる上記［１］に記載の銀ナノワイヤの製造法。
　ＡＭ＝ＬＭ／ＤＭ　…（１）
　ここで、ＬＭは上記平均長さをｎｍの単位で表した値、ＤＭは上記平均直径をｎｍの単位で表した値である。
　［３］前記有機酸エステルが、酢酸メチル、酢酸エチル、酢酸プロピル、酢酸ブチルの１種または２種以上である上記［１］または［２］に記載の銀ナノワイヤの製造法。
　［４］前記ポリマーが、ＰＶＰ（ポリビニルピロリドン）またはビニルピロリドンと親水性モノマーとのコポリマーである上記［１］～［３］のいずれかに記載の銀ナノワイヤの製造法。
　［５］前記ポリマーが、ビニルピロリドンと、ジアリルジメチルアンモニウム塩、エチルアクリレート、２－ヒドロキシエチルアクリレート、２－ヒドロキシエチルメタクリレート、４－ヒドロキシブチルアクリレート、Ｎ－メチルマレイミド、Ｎ－エチルマレイミド、Ｎ－プロピルマレイミド、Ｎ－ｔｅｒｔ－ブチルマレイミド、２－ジメチルアミノエチルメタクリレート、および２－ジエチルアミノエチルメタクリレートから選ばれる１種または２種以上のモノマーとの重合組成を有するものである上記［１］～［３］のいずれかに記載の銀ナノワイヤの製造法。
　［６］前記ポリマーは、重量平均分子量Ｍｗが３０,０００～３００,０００である上記［１］～［５］のいずれかに記載の銀ナノワイヤの製造法。
　［７］上記［１］～［６］のいずれかに記載の製造法によって得られた銀ナノワイヤ。
　［８］上記［１］～［６］のいずれかに記載の製造法によって得られた銀ナノワイヤが液状媒体中に分散している銀ナノワイヤインク。
　［９］上記［１］～［６］のいずれかに記載の製造法によって得られた銀ナノワイヤを導電素材として含有する透明導電膜。 [1] In a method of producing a silver nanowire, the process of reducing and depositing silver in the form of a wire in an alcohol solvent in which a silver compound and an organic protective agent are dissolved,
Using a polymer having a vinyl pyrrolidone structural unit as the organic protective agent,
A state in which an organic acid ester is dissolved at a concentration of 0.1 to 20.0 mmol / L in the alcohol solvent, and the reduction deposition proceeds in the liquid;
A method of producing silver nanowires characterized by
[2] The average length 15μm or more, the average diameter of 35nm or less, and the following (1) to an average aspect ratio A M is the above-mentioned [1] of silver nanowires according to the silver nanowires to reduction precipitation of 600 or more as defined by the equation Manufacturing method.
A M = L M / D M (1)
Here, L M is a value representing the average length in nm, and D M is a value representing the average diameter in nm.
[3] The method for producing a silver nanowire according to the above [1] or [2], wherein the organic acid ester is one or more of methyl acetate, ethyl acetate, propyl acetate and butyl acetate.
[4] The method for producing silver nanowires according to any one of the above [1] to [3], wherein the polymer is PVP (polyvinylpyrrolidone) or a copolymer of vinylpyrrolidone and a hydrophilic monomer.
[5] The polymer is vinyl pyrrolidone, diallyl dimethyl ammonium salt, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, N-methyl maleimide, N-ethyl maleimide, N-propyl [1] to [3] having a polymerization composition with one or more monomers selected from maleimide, N-tert-butyl maleimide, 2-dimethylaminoethyl methacrylate, and 2-diethylaminoethyl methacrylate The manufacturing method of the silver nanowire in any one of.
[6] The method for producing a silver nanowire according to any one of the above [1] to [5], wherein the polymer has a weight average molecular weight Mw of 30,000 to 300,000.
[7] A silver nanowire obtained by the method according to any one of the above [1] to [6].
[8] A silver nanowires ink, wherein the silver nanowires obtained by the method according to any one of the above [1] to [6] are dispersed in a liquid medium.
[9] A transparent conductive film containing, as a conductive material, the silver nanowire obtained by the method according to any one of the above [1] to [6].
　本明細書において、銀ナノワイヤの平均長さ、平均直径、平均アスペクト比は以下の定義に従う。 In the present specification, the average length, average diameter and average aspect ratio of silver nanowires follow the definitions below.
〔平均長さＬＭ〕
　電界放出形走査電子顕微鏡（ＦＥ－ＳＥＭ）による観察画像上で、ある１本の銀ナノワイヤの一端から他端までのトレース長さを、そのワイヤの長さと定義する。顕微鏡画像上に存在する個々の銀ナノワイヤの長さを平均した値を、平均長さＬＭと定義する。平均長さを算出するためには、測定対象のワイヤの総数を１００以上とする。ここでは、還元反応を終えた液から回収される銀ナノワイヤを洗浄した段階（クロスフローろ過などの精製工程に供給する前の段階）での平均長さを評価する。 [Average length L M ]
The trace length from one end of one silver nanowire to the other end of a silver nanowire is defined as the length of the wire on an image observed by a field emission scanning electron microscope (FE-SEM). A value obtained by averaging the lengths of the individual silver nanowires present on the microscopic image is defined as an average length L M. In order to calculate the average length, the total number of wires to be measured is set to 100 or more. Here, the average length in the stage in which the silver nanowires recovered from the solution after the reduction reaction were washed (stage before being supplied to the purification step such as cross flow filtration) is evaluated.
〔平均直径ＤＭ〕
　透過型電子顕微鏡（ＴＥＭ）による明視野観察画像上で、ある１本の銀ナノワイヤにおける太さ方向両側の輪郭間距離を、そのワイヤの直径と定義する。図４に本発明に従う銀ナノワイヤについてのＴＥＭによる明視野観察画像（以下「ＴＥＭ画像」という。）を例示する。各ワイヤは全長にわたってほぼ均等な太さを有しているとみなすことができる。従って、太さの計測は他のワイヤと重なっていない部分を選択して行うことができる。１つの視野を写したＴＥＭ画像において、その画像内に観察される銀ナノワイヤのうち、他のワイヤと完全に重なって直径の計測が困難であるワイヤを除く全てのワイヤの直径を測定する、という操作を無作為に選んだ複数の視野について行い、合計１００本以上の異なる銀ナノワイヤの直径を求め、個々の銀ナノワイヤの直径の平均値を算出し、その値を平均直径ＤＭと定義する。 [Average diameter D M ]
On a bright field observation image by a transmission electron microscope (TEM), the distance between contours on both sides in the thickness direction of one silver nanowire is defined as the diameter of the wire. FIG. 4 exemplifies a TEM bright-field observation image (hereinafter referred to as “TEM image”) of silver nanowires according to the present invention. Each wire can be considered to have a substantially even thickness over its entire length. Therefore, thickness measurement can be performed by selecting a portion that does not overlap other wires. In the TEM image of one field of view, among the silver nanowires observed in the image, the diameters of all the wires except for the wires completely overlapping with other wires and whose diameter is difficult to measure are measured. The operation is performed on a plurality of randomly selected fields of view, the diameters of a total of 100 or more different silver nanowires are determined, the average value of the diameters of the individual silver nanowires is calculated, and the value is defined as the average diameter D M.
〔平均アスペクト比〕
　上記の平均直径ＤＭおよび平均長さＬＭを下記（１）式に代入することにより平均アスペクト比ＡＭを算出する。ただし、（１）式に代入するＤＭ、ＬＭはいずれもｎｍの単位で表された値とする。
　ＡＭ＝ＬＭ／ＤＭ　…（１） [Average aspect ratio]
The average aspect ratio AM is calculated by substituting the above average diameter D M and the average length L M into the following equation (1). However, it is assumed that D M and L M to be substituted into the equation (1) are both values expressed in nm.
A M = L M / D M (1)
　本発明に従えば、平均直径が例えば３５ｎｍ以下といった細い銀ナノワイヤにおいて、特に平均長さが１５ｎｍ以上、平均アスペクト比が６００以上という長い銀ナノワイヤを安定して合成することができる。合成後に行う洗浄を終えた段階で上記のような平均長さの長い銀ナノワイヤが得られるので、その後にクロスフローろ過などによってワイヤの長さ分布を調整する精製操作を行うと、平均長さが一層長く、アスペクト比の高い銀ナノワイヤを歩留り良く製造することができる。それを透明導電膜の導電素材として使用すると、高い導電性を維持しながら、ヘイズの少ない視認性に優れる透明導電膜が実現できる。 According to the present invention, it is possible to stably synthesize long silver nanowires having an average length of, for example, 15 nm or more and an average aspect ratio of 600 or more, for thin silver nanowires having an average diameter of, for example, 35 nm or less. Since long silver nanowires with an average length as described above can be obtained at the stage of completion of washing after synthesis, if the purification operation to adjust the wire length distribution by cross flow filtration etc. is performed thereafter, the average length will be Longer, high aspect ratio silver nanowires can be manufactured with high yield. When it is used as a conductive material of a transparent conductive film, a transparent conductive film excellent in visibility with less haze can be realized while maintaining high conductivity.
ビニルピロリドン構造単位の構造式。Structural formula of vinyl pyrrolidone structural unit. 比較例１で得られた銀ナノワイヤのＳＥＭ写真。SEM photograph of the silver nanowire obtained in Comparative Example 1. 比較例１で得られた銀ナノワイヤのＴＥＭ写真。TEM photograph of the silver nanowire obtained in Comparative Example 1. 実施例３で得られた銀ナノワイヤのＳＥＭ写真。SEM photograph of the silver nanowire obtained in Example 3. 実施例３で得られた銀ナノワイヤのＴＥＭ写真。TEM photograph of the silver nanowire obtained in Example 3.
　上述のように、銀ナノワイヤの合成法として、銀化合物、有機保護剤が溶解しているアルコール溶媒中で、溶媒であるアルコールの還元力を利用して銀をワイヤ状に析出させる手法が既に実用化されている。この手法を本明細書では「アルコール溶媒還元法」と呼んでいる。 As described above, as a method of synthesizing silver nanowires, a method of precipitating silver in the form of a wire using the reducing power of alcohol as a solvent in an alcohol solvent in which a silver compound and an organic protective agent are dissolved has already been put to practical use It has been This method is called "alcohol solvent reduction method" in the present specification.
　アルコール溶媒還元法で金属銀をワイヤ状に析出させるには、銀の多重双晶であると考えられる核結晶の｛１００｝面に、有機保護剤のポリマー分子が選択的に吸着することが必要である。それにより｛１００｝面の成長が抑制され、銀結晶の最密面である｛１１１｝面が優先的に成長し、金属銀の線状構造体が形成される。ポリマー分子の選択吸着性は、ポリマー分子の表面電位と銀の結晶面の表面電位の相互作用によって生じると考えられている。銀結晶｛１００｝面への選択吸着性に優れるポリマーとして、ビニルピロリドン構造単位を有するホモポリマー（ＰＶＰ）やコポリマーが知られている。図１にビニルピロリドン構造単位の構造式を示す。このようなポリマーを主体とする有機保護剤がアルコール溶媒中に溶解している状況下で銀の還元析出を進行させると、｛１１１｝結晶面への銀の析出が優先的に起こり、ロッド状あるいは線状の金属銀構造体が得られる。ただし、銀ナノワイヤを安定して合成するためには、｛１１１｝結晶面を活性化させる作用のあるハロゲン化物等を溶媒中に共存させておくことが一般的である。 In order to deposit metallic silver in the form of a wire by alcohol solvent reduction method, it is necessary for the polymer molecule of the organic protective agent to be selectively adsorbed on the {100} face of the nucleus crystal that is considered to be multiple twins of silver. It is. Thereby, the growth of the {100} plane is suppressed, the {111} plane which is the closest surface of the silver crystal is preferentially grown, and a linear structure of metallic silver is formed. The selective adsorptivity of polymer molecules is believed to be caused by the interaction between the surface potential of the polymer molecules and the surface potential of the silver crystal face. Homopolymers (PVP) and copolymers having vinyl pyrrolidone structural units are known as polymers excellent in selective adsorption to the silver crystal {100} plane. The structural formula of a vinyl pyrrolidone structural unit is shown in FIG. When the reduction deposition of silver proceeds under the condition that the organic protective agent mainly composed of such a polymer is dissolved in the alcohol solvent, the deposition of silver on the {111} crystal plane preferentially occurs, resulting in a rod shape. Alternatively, a linear metallic silver structure is obtained. However, in order to stably synthesize silver nanowires, it is general to coexist a halide or the like having the function of activating the {111} crystal plane in a solvent.
　発明者は、ビニルピロリドン構造単位を有するポリマーを有機保護剤に用いて細い銀ナノワイヤを合成するに際し、特に合成されるワイヤの平均長さを向上させる手法について種々検討してきた。その結果、従来一般的に使用されているハロゲン化物等の添加剤の他に、有機酸エステルを添加することが極めて有効であることを知見した。有機酸エステルは、アルコール溶媒還元法で銀ナノワイヤを合成する際に、銀が優先的に析出していく｛１１１｝結晶面を清浄化する作用、すなわち｛１１１｝結晶面への有機保護剤分子の吸着を抑止するとともに露出している｛１１１｝結晶面を活性化させて新たな銀の析出を促進させる作用を有すると考えられる。｛１１１｝結晶面を活性化させる作用は、従来一般的な添加剤であるハロゲン化物等が主として担うが、有機酸エステルもこれと類似の働きをするものと推察される。既に析出した金属銀の線状構造体の近傍に、ハロゲンに加えて有機酸エステルが存在すると、上記清浄化の作用が増大し、線状構造体の太さ方向の表面（｛１００｝結晶面）への銀の析出のし易さに対する、長さ方向の露出表面（｛１１１｝結晶面）への相対的な析出のし易さがより一層高まり、結果的に平均アスペクト比の大きい銀ナノワイヤの合成が容易になるものと考えられる。 The inventors have variously studied a method for improving the average length of the synthesized wire particularly when synthesizing a thin silver nanowire using a polymer having a vinyl pyrrolidone structural unit as an organic protective agent. As a result, it has been found that the addition of an organic acid ester is extremely effective in addition to conventionally used additives such as halides. The organic acid ester acts to clean the {111} crystal face on which silver preferentially precipitates when synthesizing silver nanowires by the alcohol solvent reduction method, ie, an organic protective agent molecule to the {111} crystal face It is thought that it has the effect of suppressing the adsorption of and activating the exposed {111} crystal face to promote the deposition of new silver. The action to activate the {111} crystal face is mainly borne by the conventional additives such as halides, but it is presumed that the organic acid ester also acts in a similar manner. If an organic acid ester is present in addition to the halogen in the vicinity of the metallic silver linear structure already deposited, the above-mentioned cleaning action is enhanced, and the surface in the thickness direction of the linear structure ({100} crystal plane The relative ease of deposition on the exposed surface in the longitudinal direction ({111} crystal plane) relative to the ease of deposition of silver on silver) is further enhanced, resulting in a silver nanowire with a large average aspect ratio It is considered that the synthesis of
　｛１１１｝結晶面の活性化作用を強化する目的でハロゲン化物の添加量を増大させることには問題がある。合成された銀ナノワイヤの表面を被覆する有機保護剤には、合成時に添加された塩素等のハロゲン原子が付着しており、そのハロゲン原子は、銀ナノワイヤに随伴して透明導電膜の中に入り込む。発明者の調査によれば、透明導電膜中の塩素濃度が高いと、透明導電膜の経時劣化が促進され、早期に導電性が低下するという問題が生じやすいことが確認されている。この点、有機酸エステルの添加によって｛１１１｝結晶面の清浄化作用を強化する手法では、上記のような透明導電膜の経時劣化の問題は回避される。 There is a problem in increasing the amount of halide added for the purpose of enhancing the activation action of the {111} crystal face. The organic protective agent which coats the surface of the synthesized silver nanowire is attached with a halogen atom such as chlorine added at the time of synthesis, and the halogen atom is entrained into the transparent conductive film in association with the silver nanowire. . According to the inventor's investigation, it is confirmed that when the concentration of chlorine in the transparent conductive film is high, the deterioration with time of the transparent conductive film is promoted, and a problem that the conductivity is deteriorated early tends to occur. In this respect, in the method of strengthening the cleaning action of the {111} crystal face by the addition of the organic acid ester, the problem of the above-mentioned deterioration of the transparent conductive film with time can be avoided.
　種々検討の結果、アルコール溶媒中に有機酸エステルが０.１ｍｍｏｌ／Ｌ（＝０.１×１０－３ｍｏｌ／Ｌ）以上の濃度で溶解している状態で還元析出を進行させることにより、合成される銀ナノワイヤの平均長さを向上させる効果が顕著に発揮される。有機酸エステル濃度を０.５ｍｍｏｌ／Ｌ（＝０.５×１０－３ｍｏｌ／Ｌ）以上とすることがより好ましい。ただし、有機酸エステル濃度が高くなると銀ナノワイヤの平均長さを向上させる効果は飽和してくる。溶媒中の有機酸エステル濃度は２０.０ｍｍｏｌ／Ｌ（２０.０×１０－３ｍｏｌ／Ｌ）以下の範囲で設定すればよく、１５.０ｍｍｏｌ／Ｌ（１５.０×１０－３ｍｏｌ／Ｌ）以下に管理してもよい。 As a result of various investigations, synthesis is carried out by proceeding reduction deposition in a state in which the organic acid ester is dissolved at a concentration of 0.1 mmol / L (= 0.1 × 10 −3 mol / L) or more in an alcohol solvent. The effect of improving the average length of the silver nanowires to be It is more preferable that the organic acid ester concentration be 0.5 mmol / L (= 0.5 × 10 −3 mol / L) or more. However, when the concentration of the organic acid ester is increased, the effect of improving the average length of the silver nanowires is saturated. The concentration of the organic acid ester in the solvent may be set in the range of 20.0 mmol / L (20.0 × 10 −3 mol / L) or less, and 15.0 mmol / L (15.0 × 10 −3 mol / L) ) You may manage as follows.
　還元析出反応時のアルコール溶媒中に存在する有機保護剤との量比で見ると、例えば有機保護剤であるビニルピロリドン構造単位を持つポリマー１モルに対し、有機酸エステルの液中存在量を０.００１～０.３モルの範囲で調整することが好ましい。また、銀との量比で見ると、反応に使用する銀の総量１モルに対し、有機酸エステルの液中存在量を反応開示時点において０.００１～０.５モルの範囲で調整することが好ましい。 The amount ratio of the organic acid ester in the solution is 0 per 1 mol of the polymer having a vinylpyrrolidone structural unit, which is an organic protective agent, in terms of the quantitative ratio to the organic protective agent present in the alcohol solvent at the time of the reductive deposition reaction. It is preferable to adjust in the range of .001 to 0.3 mol. Also, in terms of quantitative ratio to silver, adjust the amount of the organic acid ester in the liquid to be in the range of 0.001 to 0.5 mol at the time of reaction disclosure with respect to 1 mol of the total amount of silver used for the reaction. Is preferred.
　有機酸エステルとしては、例えば、アジピン酸ジエチル（Ｃ１０Ｈ１８Ｏ４）、アセチルクエン酸トリエチル（Ｃ１４Ｈ２２Ｏ８）、安息香酸イソアミル（Ｃ１２Ｈ１６Ｏ２）、安息香酸エチル（Ｃ９Ｈ１０Ｏ２）、イソ吉草酸エチル（Ｃ７Ｈ１４Ｏ２）、ギ酸エチル（Ｃ３Ｈ６Ｏ２）、ギ酸ブチル（Ｃ５Ｈ１０Ｏ２）、クエン酸トリブチル（Ｃ１８Ｈ３２Ｏ７）、シュウ酸ジエチル（Ｃ６Ｈ１０Ｏ４）、酒石酸ジエチル（Ｃ８Ｈ１４Ｏ６）、ステアリン酸エチル（Ｃ２０Ｈ４０Ｏ２）、乳酸エチル（Ｃ５Ｈ１０Ｏ３）、フタル酸ジエチル（Ｃ１２Ｈ１４Ｏ４）、プロピオン酸エチル（Ｃ５Ｈ１０Ｏ２）、マレイン酸ジイソプロピル（Ｃ１０Ｈ１６Ｏ４）、マロン酸ジエチル（Ｃ７Ｈ１２Ｏ４）、酪酸エチル（Ｃ６Ｈ１２Ｏ２）や、酢酸メチル（Ｃ３Ｈ６Ｏ２）、酢酸エチル（Ｃ４Ｈ８Ｏ２）、酢酸プロピル（Ｃ５Ｈ１０Ｏ２）、酢酸ブチル（Ｃ６Ｈ１２Ｏ２）、アセト酢酸エチル（Ｃ６Ｈ１０Ｏ３）、アセト酢酸メチル（Ｃ５Ｈ８Ｏ３）、酢酸アミル（Ｃ７Ｈ１４Ｏ２）、酢酸イソブチル（Ｃ６Ｈ１２Ｏ２）、酢酸ベンジル（Ｃ９Ｈ１０Ｏ２）等の酢酸エステルが挙げられる。有機酸エステルは、１種または２種以上を使用することができる。 Examples of the organic acid ester include diethyl adipate (C 10 H 18 O 4 ), triethyl acetyl citrate (C 14 H 22 O 8 ), isoamyl benzoate (C 12 H 16 O 2 ), ethyl benzoate (C 9 H 10 O 2 ), ethyl isovalerate (C 7 H 14 O 2 ), ethyl formate (C 3 H 6 O 2 ), butyl formate (C 5 H 10 O 2 ), tributyl citrate (C 18 H 32) O 7 ), diethyl oxalate (C 6 H 10 O 4 ), diethyl tartrate (C 8 H 14 O 6 ), ethyl stearate (C 20 H 40 O 2 ), ethyl lactate (C 5 H 10 O 3 ), diethyl phthalate (C 12 H 14 O 4) , ethyl propionate (C 5 H 10 O 2) , diisopropyl maleate (C 10 H 16 O 4) , diethyl malonate C 7 H 12 O 4), and ethyl butyrate (C 6 H 12 O 2) , methyl acetate (C 3 H 6 O 2) , ethyl acetate (C 4 H 8 O 2) , propyl acetate (C 5 H 10 O 2 ), butyl acetate (C 6 H 12 O 2 ), ethyl acetoacetate (C 6 H 10 O 3 ), methyl acetoacetate (C 5 H 8 O 3 ), amyl acetate (C 7 H 14 O 2 ), acetic acid Acetic acid esters such as isobutyl (C 6 H 12 O 2 ), benzyl acetate (C 9 H 10 O 2 ) and the like can be mentioned. One or more organic acid esters can be used.
　有機保護剤として使用するビニルピロリドン構造単位を持つポリマーとして、ＰＶＰ（ポリビニルピロリドン）またはビニルピロリドンと親水性モノマーとのコポリマーが好適な対象となる。後者のコポリマーとしては、例えば、ビニルピロリドンと、ジアリルジメチルアンモニウム塩、エチルアクリレート、２－ヒドロキシエチルアクリレート、２－ヒドロキシエチルメタクリレート、４－ヒドロキシブチルアクリレート、Ｎ－メチルマレイミド、Ｎ－エチルマレイミド、Ｎ－プロピルマレイミドおよびＮ－ｔｅｒｔ－ブチルマレイミドから選ばれる１種または２種以上のモノマーとの重合組成を有するコポリマーが挙げられる。コポリマーの重合組成は、ビニルピロリドン以外のモノマー０.１～１０質量％、残部ビニルピロリドンであることが好ましい。 As a polymer having a vinylpyrrolidone structural unit used as an organic protective agent, PVP (polyvinylpyrrolidone) or a copolymer of vinylpyrrolidone and a hydrophilic monomer is a suitable target. The latter copolymers include, for example, vinyl pyrrolidone and diallyl dimethyl ammonium salt, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, N-methyl maleimide, N-ethyl maleimide, N- Examples include copolymers having a polymerization composition with one or more monomers selected from propyl maleimide and N-tert-butyl maleimide. The polymerization composition of the copolymer is preferably 0.1 to 10% by weight of monomers other than vinyl pyrrolidone, with the balance being vinyl pyrrolidone.
　有機保護剤に使用するポリマーの重量平均分子量Ｍｗは３０,０００～３００,０００の範囲にあることが好ましく、３０,０００～１５０,０００の範囲であることがより好ましい。ＭｗはＧＰＣ（ゲル浸透クロマトグラフィー）により求めることができる。 The weight average molecular weight Mw of the polymer used for the organic protective agent is preferably in the range of 30,000 to 300,000, and more preferably in the range of 30,000 to 150,000. Mw can be determined by GPC (gel permeation chromatography).
　ポリマーを合成する過程では、重合生成したポリマーを精製する際の有機溶剤として酢酸エステルが使用されることがある。その場合には、ポリマーの粉体製品中に酢酸エステルが不純物として混入している。ただし、本発明ではアルコール溶媒中における有機酸エステル濃度を上述の所定範囲に調整するうえで、溶媒中に導入する有機酸エステルの一部をポリマー粉体中に存在している酢酸エステルによって賄う必要はないので、ビニルピロリドン構造単位を持つポリマー１モルに対し酢酸エステル混入量が例えば０.００２モル未満であるポリマー粉体を有機保護剤の供給源として使用することができる。この場合、ポリマー粉体からアルコール溶媒中に導入される酢酸エステルは少量であるため、アルコール溶媒中の有機酸エステル濃度の算出には無視して構わない。なお、ポリマー粉体中の酢酸エステル存在量は、ポリマー粉体のＮＭＲ（核磁気共鳴）スペクトルから求めることができる。 In the process of synthesizing the polymer, acetic acid ester may be used as an organic solvent in purifying the polymer formed by polymerization. In that case, acetic acid ester is mixed as an impurity in the polymer powder product. However, in the present invention, in order to adjust the concentration of the organic acid ester in the alcohol solvent to the above-mentioned predetermined range, it is necessary to compensate a part of the organic acid ester introduced into the solvent by the acetic acid ester present in the polymer powder. Since there is not, polymer powder having an acetic acid ester content of, for example, less than 0.002 mol can be used as a source of the organic protective agent with respect to 1 mol of the polymer having a vinyl pyrrolidone structural unit. In this case, since the amount of acetic acid ester introduced from the polymer powder into the alcohol solvent is small, it can be ignored in the calculation of the concentration of the organic acid ester in the alcohol solvent. The amount of acetic acid ester in the polymer powder can be determined from the NMR (nuclear magnetic resonance) spectrum of the polymer powder.
〔銀ナノワイヤの寸法形状〕
　銀ナノワイヤは、導電性と視認性に優れた透明導電塗膜を形成する観点から、できるだけ細くて長い形状であるものが好ましい。本発明では、平均長さが１５μｍ以上、平均直径が３５ｎｍ以下、かつ前記（１）式による平均アスペクト比が６００以上であるものが好適な対象となる。平均長さが１５μｍ以上、平均直径が３３ｎｍ以下であるものがより好適な対象となる。平均長さが１５μｍ以上、平均直径が３０ｎｍ以下であるものがさらに好適な対象となる。本発明では、合成段階で平均長さが長く、平均アスペクト比が大きい銀ナノワイヤを得ることができるので、その後の工程で、例えばクロスフロー精製によって長さ分布を高い歩留りで効率的に調整することができる。 [Dimensional shape of silver nanowires]
The silver nanowire is preferably as thin and long as possible from the viewpoint of forming a transparent conductive coating film excellent in conductivity and visibility. In the present invention, an object having an average length of 15 μm or more, an average diameter of 35 nm or less, and an average aspect ratio of 600 or more according to the equation (1) is suitable. It is more preferable that the average length is 15 μm or more and the average diameter is 33 nm or less. It is more preferable that the average length is 15 μm or more and the average diameter is 30 nm or less. In the present invention, silver nanowires having a long average length and a large average aspect ratio can be obtained in the synthesis stage, so that the length distribution can be efficiently adjusted at a high yield, for example, by cross flow purification in the subsequent steps. Can.
〔銀ナノワイヤの合成〕
　アルコール溶媒中に有機酸エステルを存在させることを除き、従来から開発されているアルコール溶媒還元法の技術を利用することができる。溶媒であるアルコールの種類としては、銀に対して適度な還元力を有し、金属銀をワイヤ状に析出させることができるものが選択される。例えば、エチレングリコール、プロピレングリコール（１,２－プロパンジオール）、１,３－プロパンジオール、１,３ブタンジオール、１,４－ブタンジオール、グリセリンの１種以上からなるアルコール溶媒を使用することができる。これらのアルコールは単独で用いてもよいし、２種以上混合して用いてもよい。銀源として、アルコール溶媒に可溶な銀化合物を使用する。例えば、硝酸銀、酢酸銀、酸化銀、塩化銀などが挙げられるが、溶媒に対する溶解性やコストを考慮すると硝酸銀（ＡｇＮＯ３）が使いやすい。銀化合物、有機保護剤、有機酸エステルの他に、塩化物、臭化物が溶解しているアルコール溶媒中で還元析出を進行させることが好ましい。更にアルカリ金属水酸化物、アルミニウム塩が溶解しているアルコール溶媒中で還元析出を進行させてもよい。例えば、上記特許文献１に開示される手法において、有機酸エステルを添加したアルコール溶媒を適用することができる。 [Synthesis of silver nanowires]
Conventional techniques for alcohol solvent reduction can be used except for the presence of the organic acid ester in the alcohol solvent. As a kind of alcohol which is a solvent, what has moderate reducing power with respect to silver, and can precipitate metallic silver in a wire form is selected. For example, using an alcohol solvent comprising one or more of ethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, 1,3 butanediol, 1,4-butanediol, and glycerin it can. These alcohols may be used alone or in combination of two or more. As a silver source, a silver compound soluble in alcohol solvent is used. For example, silver nitrate, silver acetate, silver oxide, silver chloride and the like can be mentioned, but silver nitrate (AgNO 3 ) is easy to use in consideration of the solubility in a solvent and the cost. In addition to the silver compound, the organic protective agent and the organic acid ester, it is preferable to proceed the reduction deposition in an alcohol solvent in which a chloride and a bromide are dissolved. Furthermore, reduction deposition may be allowed to proceed in an alcohol solvent in which an alkali metal hydroxide or aluminum salt is dissolved. For example, in the method disclosed in Patent Document 1, an alcohol solvent to which an organic acid ester is added can be applied.
〔比較例１〕
（有機保護剤）
　溶媒であるメチルイソブチルケトンに、１－ビニル２ピロリドンと、ジアリルジメチルアンモニウムナイトレート（ｄｉａｌｌｙｌｄｉｍｅｔｈｙｌａｍｍｏｎｉｕｍ　ｎｉｔｒａｔｅ）を溶解させ、重合開始剤を添加して共重合させる手法で合成されたコポリマー粉体を用意した。重合組成は、モル比で１－ビニル２ピロリドン：ジアリルジメチルアンモニウムナイトレート＝９９：１である。 Comparative Example 1
(Organic protective agent)
A copolymer powder was prepared by dissolving 1-vinyldipyrrolidone and diallyldimethylammonium nitrate in a solvent, methyl isobutyl ketone, as a solvent, and copolymerizing by adding a polymerization initiator. The polymerization composition is 1-vinyldipyrrolidone: diallyldimethylammonium nitrate = 99: 1 in molar ratio.
　コポリマー粉体について、日本電子社製、ＪＮＭ－ＬＡ４００（４００ＭＨｚ）により核磁気共鳴分光法（ＮＭＲ）で１Ｈ　ＮＭＲスペクトルを測定し、当該粉体に含まれる成分を調べた。その結果、モル比で、ポリマー９７.２８％、残留ＶＰ（ビニルピロリドン）：１.０７％、酢酸エチル：０.０４％、ＴＢＭＥ（ｔｅｒｔ－ブチルメチルエーテル）：０.６８％、ＭＩＢＫ（メチルイソブチルケトン）：０.９３％であった。ここで、酢酸エチルは４.１ｐｐｍ付近のピークの積分値を、ＴＢＭＥは１.２ｐｐｍ付近のピークの積分値を、ＭＩＢＫは０.９ｐｐｍ付近のピークの積分値を用いて各成分のモル％を算出した。残留ＶＰ量は下記（２）式により定めた。
　ＶＰＲ（ｍｏｌ％）＝［２×（Ｉ１＋Ｉ２）／（３×Ｉ３）］×１００　…（２）
　ここで、Ｉ１はＶＰモノマーのＣ＝Ｃ二重結合に関わるメチンプロトンに由来するピーク（７.０－７.２ｐｐｍ）の積分値、Ｉ２は同モノマーのＣ＝Ｃ二重結合に関わるメチレンプロトンに由来するピーク（４.３－４.４ｐｐｍ）の積分値、Ｉ３はポリマーのＮ原子に隣接するメチレンプロトンに由来するピーク（３.０－３.４ｐｐｍ）の積分値である。 The 1 H NMR spectrum of the copolymer powder was measured by nuclear magnetic resonance spectroscopy (NMR) with JNM-LA400 (400 MHz) manufactured by JEOL Ltd., and the components contained in the powder were examined. As a result, in molar ratio, polymer 97.28%, residual VP (vinyl pyrrolidone): 1.07%, ethyl acetate: 0.04%, TBME (tert-butyl methyl ether): 0.68%, MIBK (methyl) Isobutyl ketone): 0.93%. Here, ethyl acetate uses the integral value of the peak around 4.1 ppm, TBME uses the integral value of the peak around 1.2 ppm, and MIBK uses the integral value of the peak around 0.9 ppm, and the mol% of each component is Calculated. The residual VP amount was determined by the following equation (2).
VP R (mol%) = [2 × (I 1 + I 2 ) / (3 × I 3 )] × 100 (2)
Here, I 1 is the integrated value of the peak (7.0-7.2 ppm) derived from the methine proton related to the C = C double bond of the VP monomer, and I 2 is related to the C = C double bond of the same monomer integral value of peaks derived from the methylene protons (4.3-4.4ppm), I 3 is the integral value of the peak (3.0-3.4ppm) derived from the methylene protons adjacent to the N atom of the polymer.
　また、上記コポリマーの重量平均分子量ＭｗをＧＰＣ（ゲル浸透クロマトグラフィー）により下記の条件で求めた。
・装置：ＨＬＣ－８３２０ＧＰＣ　ＥｃｏＳＥＣ（東ソー社製）
・カラム：ＴＳＫｇｅｌ　ＧＭＰＷＸＬ（×２）＋Ｇ２５００ＰＷＸＬ
・溶離液：１００ｍＭ硝酸ナトリウム水溶液／アセトニトリル＝８０／２０
・流速：１.０ｍＬ／ｍｉｎ
・温度：４０℃
・注入量：２００μＬ
・多角度光散乱検出器：ＤＡＷＮ　ＨＥＬＥＯＳ　II（Ｗｙａｔｔ　Ｔｅｃｈｎｏｌｏｇｙ社製）
・屈折率（ＲＩ）検出器：Ｏｐｔｉｌａｂ　Ｔ－ｒＥＸ（Ｗｙａｔｔ　Ｔｅｃｈｎｏｌｏｇｙ社製）
　その結果、重量平均分子量Ｍｗは８４,０００であった。 Further, the weight average molecular weight Mw of the above copolymer was determined by GPC (gel permeation chromatography) under the following conditions.
・ Device: HLC-8320GPC EcoSEC (made by Tosoh Corporation)
・ Column: TSKgel GMPWXL (× 2) + G2500PWXL
Eluent: 100 mM aqueous sodium nitrate solution / acetonitrile = 80/20
・ Flow rate: 1.0 mL / min
Temperature: 40 ° C
Injection volume: 200 μL
-Multi-angle light scattering detector: DAWN HELEOS II (manufactured by Wyatt Technology)
Refractive index (RI) detector: Optilab T-rEX (manufactured by Wyatt Technology)
As a result, the weight average molecular weight Mw was 84,000.
（銀ナノワイヤの合成）
　常温にて、プロピレングリコール５１３.５ｇ中に、塩化リチウム含有量が１０質量％であるプロピレングリコール溶液０.３０２ｇ、臭化カリウム含有量が１質量％であるプロピレングリコール溶液０.８９３ｇ、水酸化リチウム０.０２２２ｇ、硝酸アルミニウム九水和物含有量が２０質量％であるプロピレングリコール溶液０.３１２ｇ、および有機保護剤の供給源である上記コポリマー粉体５.２４ｇを添加して溶解させ、溶液Ａとした。この例では溶液Ａ中に有機酸エステルを添加していない。これとは別の容器中で、プロピレングリコール５.９８ｇと純水０.５ｇの混合溶液中に硝酸銀４.２５ｇを添加して、３５℃で撹拌して溶解させ、銀を含有する溶液Ｂを得た。 (Synthesis of silver nanowires)
0.302 g of a propylene glycol solution having a lithium chloride content of 10% by mass in 513.5 g of propylene glycol at normal temperature, 0.893 g of a propylene glycol solution having a potassium bromide content of 1% by mass, lithium hydroxide 0.0222 g, 0.312 g of a propylene glycol solution having an aluminum nitrate nonahydrate content of 20% by mass, and 5.24 g of the above-mentioned copolymer powder as a source of an organic protective agent are added and dissolved, and solution A And In this example, no organic acid ester is added to the solution A. In a separate container, 4.25 g of silver nitrate is added to a mixed solution of 5.98 g of propylene glycol and 0.5 g of pure water, and the solution B containing silver is dissolved by stirring at 35 ° C. Obtained.
　上記の溶液Ａを反応容器に入れ、常温から９５℃まで回転数２５０ｒｐｍで撹拌しながら昇温したのち、溶液Ａの中に、溶液Ｂの全量を２個の添加口からチューブポンプを用いて１分かけて添加した。溶液Ｂの添加終了後、プロピレングリコール溶液４ｇを溶液Ｂが付着したチューブ内を洗い流すため、チューブポンプを用いて添加した後、さらに撹拌状態を維持して９５℃で３.５時間保持し、８５℃まで２.０時間かけて冷却し、８５℃で１９時間保持した。その後、反応液を常温まで冷却することで、銀ナノワイヤを合成した。 The above solution A is put in a reaction vessel and heated from normal temperature to 95 ° C. with stirring at a rotational speed of 250 rpm, and then the whole solution B is added to solution A using a tube pump from two addition ports. Added over a minute. After the addition of solution B, 4 g of a propylene glycol solution is added using a tube pump in order to wash out the inside of the tube to which solution B adheres, and then it is kept stirring at 95 ° C. for 3.5 hours. Cooled to 0 C over 2.0 hours and held at 85 0 C for 19 hours. Then, the silver nanowire was synthesize | combined by cooling a reaction liquid to normal temperature.
（銀ナノワイヤの平均直径、平均長さ測定）
　常温まで冷却された上記反応液２０ｇを遠沈管に分取し、純水１８０ｇ添加し、遠心分離機により１５００ｒｐｍで１５分間の遠心分離操作を行った。濃縮物と上澄みが観察されたため、上澄み部分は除去し、濃縮物を回収した。この洗浄操作を更に数回繰り返し、濃縮物を得た。得られた濃縮物を純水に分散させた。銀ナノワイヤの長さ測定においては、その分散液をＳＥＭ用の観察台にとり、観察台上で水を揮発させたのち、電界放出形走査電子顕微鏡（株式会社日立ハイテクノロジーズ製；Ｓ－４７００）により、加速電圧３ｋＶ、倍率１,５００倍で観察を行った。無作為に選んだ３以上の視野について、視野内で全長が確認できるすべてのワイヤを対象として、上述の定義に従って平均長さを測定した。直径測定においては、上記分散液をＴＥＭ用の観察台にとり、透過型電子顕微鏡（日本電子株式会社製；ＪＥＭ-１０１１）により、加速電圧１００ｋＶ、倍率４０,０００倍で明視野像の観察を行って観察画像を採取し、正確に直径を測定するために採取された元画像を２倍のサイズに拡大した上で、ソフトウェア（Ｍｏｔｉｃ Ｉｍａｇｅ Ｐｌｕｓ２.１Ｓ）を用いて、上述の定義に従って平均直径を測定した。この平均長さおよび平均直径の値を前記（１）式に代入することにより平均アスペクト比を求めた。銀ナノワイヤの平均直径は３５.８ｎｍ、平均長さは１４.１μｍであった。平均アスペクト比は、１４１００（ｎｍ）／３５.８（ｎｍ）≒３９４であった。結果を他の実施例、比較例とともに表１にまとめてある。 (Average diameter of silver nanowires, average length measurement)
20 g of the reaction solution cooled to room temperature was taken into a centrifuge tube, 180 g of pure water was added, and centrifugation was performed at 1500 rpm for 15 minutes using a centrifuge. Since the concentrate and the supernatant were observed, the supernatant portion was removed and the concentrate was recovered. This washing operation was repeated several more times to obtain a concentrate. The obtained concentrate was dispersed in pure water. In measuring the length of silver nanowires, the dispersion is placed on an observation table for SEM, water is volatilized on the observation table, and then a field emission scanning electron microscope (manufactured by Hitachi High-Technologies Corporation; S-4700) The observation was performed at an acceleration voltage of 3 kV and a magnification of 1,500. For three or more randomly selected fields of view, the average length was measured according to the above definition for all wires whose full length can be confirmed in the field of view. In the diameter measurement, the dispersion was placed on an observation table for TEM, and bright field images were observed at an acceleration voltage of 100 kV and a magnification of 40,000 with a transmission electron microscope (manufactured by JEOL Ltd .; JEM-1011). The observation image is taken, and the original image taken to accurately measure the diameter is enlarged to twice the size, and then using software (Motic Image Plus 2.1 S), the average diameter is determined according to the above definition. It was measured. The average aspect ratio was determined by substituting the values of the average length and the average diameter into the equation (1). The average diameter of the silver nanowires was 35.8 nm, and the average length was 14.1 μm. The average aspect ratio was 14100 (nm) /35.8 (nm) ≒ 394. The results are summarized in Table 1 together with other examples and comparative examples.
〔実施例１〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.００５２ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は０.１１９ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は３２.６ｎｍ、平均長さは１９.６μｍであった。平均アスペクト比は、１９６００（ｎｍ）／３２.６（ｎｍ）≒６０１であった。 Example 1
The same as in Comparative Example 1, except that, in addition to each of the substances mixed in Comparative Example 1, 0.0052 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 0.119 mmol / L. The average diameter of silver nanowires obtained under this condition was 32.6 nm, and the average length was 19.6 μm. The average aspect ratio was 19600 (nm) /32.6 (nm) ≒ 601.
〔実施例２〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.０１３１ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は０.２９８ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は３２.１ｎｍ、平均長さは１９.６μｍであった。平均アスペクト比は、１９６００（ｎｍ）／３２.１（ｎｍ）≒６１１であった。 Example 2
The same as in Comparative Example 1, except that, in addition to the respective substances mixed in Comparative Example 1, 0.0131 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 0.298 mmol / L. The average diameter of silver nanowires obtained under this condition was 32.1 nm, and the average length was 19.6 μm. The average aspect ratio was 19600 (nm) /32.1 (nm) 611 611.
〔実施例３〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.０２６３ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は０.５９８ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２８.５ｎｍ、平均長さは２１.８μｍであった。平均アスペクト比は、２１８００（ｎｍ）／２８.５（ｎｍ）≒７６５であった。 [Example 3]
The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0263 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (ie, the initiation of the addition of solution B) is 0.598 mmol / L. The average diameter of silver nanowires obtained under this condition was 28.5 nm, and the average length was 21.8 μm. The average aspect ratio was 21800 (nm) /28.5 (nm) 765 765.
〔実施例４〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.０７９８ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は１.８１２ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２８.４ｎｍ、平均長さは２３.３μｍであった。平均アスペクト比は、２３３００（ｎｍ）／２８.４（ｎｍ）≒８２０であった。 Example 4
The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0798 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L. The average diameter of silver nanowires obtained under this condition was 28.4 nm, and the average length was 23.3 μm. The average aspect ratio was 23300 (nm) /28.4 (nm) ≒ 820.
〔実施例５〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.１３４４ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は３.０５１ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２８.８ｎｍ、平均長さは２３.９μｍであった。平均アスペクト比は、２３９００（ｎｍ）／２８.８（ｎｍ）≒８３０であった。 [Example 5]
The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.1344 g of ethyl acetate was further mixed and dissolved as the solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 3.051 mmol / L. The average diameter of the silver nanowire obtained under this condition was 28.8 nm, and the average length was 23.9 μm. The average aspect ratio was 23900 (nm) /28.8 (nm) 830 830.
〔実施例６〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.２７５９ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は６.２６３ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２８.５ｎｍ、平均長さは２２.２μｍであった。平均アスペクト比は、２２２００（ｎｍ）／２８.５（ｎｍ）≒７７９であった。 [Example 6]
The same as in Comparative Example 1, except that 0.2759 g of ethyl acetate was further mixed and dissolved as solution A in addition to the respective materials mixed in Comparative Example 1 when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 6.263 mmol / L. The average diameter of silver nanowires obtained under this condition was 28.5 nm, and the average length was 22.2 μm. The average aspect ratio was 22200 (nm) /28.5 (nm) 779 779.
〔実施例７〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.３３４６ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は７.５９５ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２８.７ｎｍ、平均長さは２２.１μｍであった。平均アスペクト比は、２２１００（ｎｍ）／２８.７（ｎｍ）≒７７０であった。 [Example 7]
The same method as Comparative Example 1 was used except that, in addition to the respective materials mixed in Comparative Example 1, 0.3346 g of ethyl acetate was further mixed and dissolved as a solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (ie, the initiation of the addition of solution B) is 7.595 mmol / L. The average diameter of the silver nanowire obtained under this condition was 28.7 nm, and the average length was 22.1 μm. The average aspect ratio was 22100 (nm) /28.7 (nm) 770 770.
〔実施例８〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.４２５０ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は９.６４８ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２９.４ｎｍ、平均長さは２３.０μｍであった。平均アスペクト比は、２３０００（ｎｍ）／２９.４（ｎｍ）≒７８２であった。 Example 8
The same as in Comparative Example 1, except that, in addition to each of the substances mixed in Comparative Example 1, 0.4250 g of ethyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 9.648 mmol / L. The average diameter of the silver nanowire obtained under this condition was 29.4 nm, and the average length was 23.0 μm. The average aspect ratio was 23000 (nm) /29.4 (nm) 782 782.
〔実施例９〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸エチル０.５８２５ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸エチル濃度は１３.２２１ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２９.２ｎｍ、平均長さは２４.５μｍであった。平均アスペクト比は、２４５００（ｎｍ）／２９.２（ｎｍ）≒８３９であった。 [Example 9]
When silver nanowires were synthesized, the same solution as in Comparative Example 1 was used except that a solution obtained by mixing and dissolving 0.5825 g of ethyl acetate in addition to the respective materials mixed in Comparative Example 1 was used. The experiment was conducted under the conditions. The ethyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 13.221 mmol / L. The average diameter of silver nanowires obtained under this condition was 29.2 nm, and the average length was 24.5 μm. The average aspect ratio was 24500 (nm) /29.2 (nm) ≒ 839.
〔実施例１０〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸メチル０.１０５２ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸メチル濃度は１.８１２ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２７.７ｎｍ、平均長さは２０.３μｍであった。平均アスペクト比は、２０３００（ｎｍ）／２７.７（ｎｍ）≒７３３であった。 [Example 10]
The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.1052 g of methyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The methyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L. The average diameter of silver nanowires obtained under this condition was 27.7 nm, and the average length was 20.3 μm. The average aspect ratio was 20300 (nm) /27.7 (nm) 733 733.
〔実施例１１〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸プロピル０.０６７１ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸プロピル濃度は１.８１２ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２８.２ｎｍ、平均長さは１８.２μｍであった。平均アスペクト比は、１８２００（ｎｍ）／２８.２（ｎｍ）≒６４５であった。 [Example 11]
The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0671 g of propyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The propyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L. The average diameter of the silver nanowire obtained under this condition was 28.2 nm, and the average length was 18.2 μm. The average aspect ratio was 18200 (nm) /28.2 (nm) 645645.
〔実施例１２〕
　銀ナノワイヤを合成するに際し、溶液Ａとして、比較例１で混合した各物質の他に、更に酢酸ブチル０.０９２５ｇを混合して溶解させたものを使用したことを除き、比較例１と同様の条件で実験を行った。銀の析出反応開始時点（すなわち溶液Ｂの添加開始時点）におけるアルコール溶媒中の酢酸ブチル濃度は１.８１２ｍｍｏｌ／Ｌである。この条件で得られた銀ナノワイヤの平均直径は２６.６ｎｍ、平均長さは１７.７μｍであった。平均アスペクト比は、１７７００（ｎｍ）／２６.６（ｎｍ）≒６６５であった。 [Example 12]
The same as in Comparative Example 1, except that, in addition to the respective materials mixed in Comparative Example 1, 0.0925 g of butyl acetate was further mixed and dissolved as solution A when synthesizing silver nanowires. The experiment was conducted under the conditions. The butyl acetate concentration in the alcohol solvent at the initiation of the precipitation reaction of silver (that is, the initiation of the addition of solution B) is 1.812 mmol / L. The average diameter of silver nanowires obtained under this condition was 26.6 nm, and the average length was 17.7 μm. The average aspect ratio was 17700 (nm) /26.6 (nm) ≒ 665.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１からわかるように、銀ナノワイヤ合成時のアルコール溶媒中に有機酸エステルを存在させると、合成されるワイヤの平均長さを顕著に向上させることができ、それに伴ってワイヤの平均アスペクト比も向上する。その効果を十分に発揮させるためにはアルコール溶媒中の有機酸エステル濃度を０.１ｍｍｏｌ／Ｌ以上とすることが好ましい。 As can be seen from Table 1, the presence of the organic acid ester in the alcohol solvent at the time of silver nanowire synthesis can significantly improve the average length of the synthesized wire, and accordingly the average aspect ratio of the wire improves. In order to exhibit the effect sufficiently, it is preferable to set the organic acid ester concentration in the alcohol solvent to 0.1 mmol / L or more.
　参考のため、図２および図３にそれぞれ比較例１で得られた銀ナノワイヤのＳＥＭ写真およびＴＥＭ写真を、図４および図５にそれぞれ実施例３で得られた銀ナノワイヤのＳＥＭ写真およびＴＥＭ写真を示す。 For reference, FIGS. 2 and 3 respectively show SEM and TEM photographs of the silver nanowire obtained in Comparative Example 1, and FIGS. 4 and 5 show SEM and TEM photographs of the silver nanowire obtained in Example 3 respectively. Indicates

Claims (9)

  1. 　銀化合物、有機保護剤が溶解しているアルコール溶媒中で、銀をワイヤ状に還元析出させる工程を有する銀ナノワイヤの製造法において、
    　前記有機保護剤としてビニルピロリドン構造単位を持つポリマーを使用すること、
    　前記アルコール溶媒中に有機酸エステルが０.１～２０.０ｍｍｏｌ／Ｌの濃度で溶解している状態とし、その液中で前記還元析出を進行させること、
    を特徴とする銀ナノワイヤの製造法。     In a method of producing a silver nanowire, comprising the step of reducing and precipitating silver in the form of a wire in an alcohol solvent in which a silver compound and an organic protective agent are dissolved,
    Using a polymer having a vinyl pyrrolidone structural unit as the organic protective agent,
    A state in which an organic acid ester is dissolved at a concentration of 0.1 to 20.0 mmol / L in the alcohol solvent, and the reduction deposition proceeds in the liquid;
    A method of producing silver nanowires characterized by
  2. 　平均長さ１５μｍ以上、平均直径３５ｎｍ以下、かつ下記（１）式で定義される平均アスペクト比ＡＭが６００以上である銀ナノワイヤを還元析出させる請求項１に記載の銀ナノワイヤの製造法。
    　ＡＭ＝ＬＭ／ＤＭ　…（１）
    　ここで、ＬＭは上記平均長さをｎｍの単位で表した値、ＤＭは上記平均直径をｎｍの単位で表した値である。     Average length 15μm or more, the average diameter of 35nm or less, and the following (1) Silver nanowires method according to claim 1 for the average aspect ratio A M is precipitated reducing silver nanowires 600 or more defined by the equation.
    A M = L M / D M (1)
    Here, L M is a value representing the average length in nm, and D M is a value representing the average diameter in nm.
  3. 　前記有機酸エステルが、酢酸メチル、酢酸エチル、酢酸プロピル、酢酸ブチルの１種または２種以上である請求項１に記載の銀ナノワイヤの製造法。 The method for producing silver nanowires according to claim 1, wherein the organic acid ester is one or more of methyl acetate, ethyl acetate, propyl acetate and butyl acetate.
  4. 　前記ポリマーが、ＰＶＰ（ポリビニルピロリドン）またはビニルピロリドンと親水性モノマーとのコポリマーである請求項１に記載の銀ナノワイヤの製造法。 The method for producing silver nanowires according to claim 1, wherein the polymer is PVP (polyvinyl pyrrolidone) or a copolymer of vinyl pyrrolidone and a hydrophilic monomer.
  5. 　前記ポリマーが、ビニルピロリドンと、ジアリルジメチルアンモニウム塩、エチルアクリレート、２－ヒドロキシエチルアクリレート、２－ヒドロキシエチルメタクリレート、４－ヒドロキシブチルアクリレート、Ｎ－メチルマレイミド、Ｎ－エチルマレイミド、Ｎ－プロピルマレイミド、Ｎ－ｔｅｒｔ－ブチルマレイミド、２－ジメチルアミノエチルメタクリレート、および２－ジエチルアミノエチルメタクリレートから選ばれる１種または２種以上のモノマーとの重合組成を有するものである請求項１に記載の銀ナノワイヤの製造法。 The polymer is selected from vinyl pyrrolidone, diallyl dimethyl ammonium salt, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, N-methyl maleimide, N-ethyl maleimide, N-propyl maleimide, N The method for producing silver nanowires according to claim 1, having a polymerization composition with one or more monomers selected from -tert-butylmaleimide, 2-dimethylaminoethyl methacrylate, and 2-diethylaminoethyl methacrylate. .
  6. 　前記ポリマーは、重量平均分子量Ｍｗが３０,０００～３００,０００である請求項１に記載の銀ナノワイヤの製造法。 The method according to claim 1, wherein the polymer has a weight average molecular weight Mw of 30,000 to 300,000.
  7. 　請求項１に記載の製造法によって得られた銀ナノワイヤ。 The silver nanowire obtained by the manufacturing method of Claim 1.
  8. 　請求項１に記載の製造法によって得られた銀ナノワイヤが液状媒体中に分散している銀ナノワイヤインク。 The silver nanowire ink which the silver nanowire obtained by the manufacturing method of Claim 1 is disperse | distributing in a liquid medium.
  9. 　請求項１に記載の製造法によって得られた銀ナノワイヤを導電素材として含有する透明導電膜。 A transparent conductive film comprising the silver nanowire obtained by the method according to claim 1 as a conductive material.
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