WO2010073420A1 - Silver particles containing copper, method for producing the same, and dispersion using the same - Google Patents

Silver particles containing copper, method for producing the same, and dispersion using the same Download PDF

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WO2010073420A1
WO2010073420A1 PCT/JP2009/002873 JP2009002873W WO2010073420A1 WO 2010073420 A1 WO2010073420 A1 WO 2010073420A1 JP 2009002873 W JP2009002873 W JP 2009002873W WO 2010073420 A1 WO2010073420 A1 WO 2010073420A1
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silver
copper
reaction
solution
protective agent
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PCT/JP2009/002873
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French (fr)
Japanese (ja)
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金田秀治
本村公一
苅安達也
久枝穣
伊波興祐
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Ｄｏｗａエレクトロニクス株式会社
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Publication of WO2010073420A1 publication Critical patent/WO2010073420A1/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
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B22F1/0545—Dispersions or suspensions of nanosized particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • 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
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

  • the present invention relates to a silver particle, a silver particle-containing dispersion, and a method for producing the silver particle that can be suitably used for wiring and electrodes of electronic devices.
  • particles having a nano-order particle size have unique properties compared to particles of micron-order or larger, and studies have been made on how to use them.
  • studies are being made on forming fine wiring on a substrate taking advantage of the size of nanoparticles and low-temperature sintering.
  • the nanoparticles are being studied for use in a wide variety of applications other than those exemplified, but their production methods are roughly classified into two patterns, a gas phase method and a liquid phase method. Since manufacturing by a vapor phase method is generally often performed under vacuum conditions, it has been cited as a disadvantage that the initial investment cost of an apparatus or the like is high and it is not suitable for mass production. In the case of the liquid phase method, it is suitable for mass production, but the particle size obtained from factors such as the difference in liquidity at the beginning and near the end of the reaction, and the variation in liquidity in the reaction tank, or Since the shape may vary, there is a problem that the particle size distribution tends to become wide as a result.
  • the reaction is often started by directly contacting a silver salt solution and a reducing agent solution.
  • the reaction occurs abruptly, and therefore the time until the reaction is completed may be in seconds when it is extreme.
  • the reaction may proceed locally from the portion where the liquid is added. In that case, it can be said that it is difficult to make the shape of the obtained particles uniform.
  • the reaction state is highly controlled, or a relatively slow reducing agent is selected, and the reaction rate is reduced, thereby achieving uniformity. Attempts have been made.
  • Nanoparticles have the problem of particle aggregation. Nanoparticles are characterized by their fine particle size, and their cohesion between particles is larger than conventionally known micron-order and sub-micron-order particles, and the particles themselves are highly reactive. Therefore, there is a case where particles are aggregated and bonded at the same time, so that a so-called coagulation state occurs, and if such a state is reached, the properties expected as nanoparticles may no longer be exhibited.
  • JP 2004-068072 A Japanese Patent Application Laid-Open No. 2007-146279
  • Patent Documents 1 and 2 both satisfy the expected problem of uniform particle diameter because nanoparticles having a uniform particle size are obtained.
  • the part inferior in terms of production management may occur.
  • problems may occur due to various factors. In such a case, it is difficult to grasp the cause of abnormality in the case of continuous reaction.
  • the particles are nano-order, it is difficult to confirm the defect in-situ.
  • continuous production is performed under defective conditions, and many products may be disposed of such as disposal.
  • the batch reaction is preferable from the viewpoint of reducing the loss as much as possible when a failure occurs.
  • the present invention provides a production method suitable for simple and mass production of nanoparticles having a uniform particle diameter, silver particles produced by the production method, and powder that is an aggregate thereof. Aimed.
  • the present inventors have found that the above object can be achieved if a reduction reaction is performed in a state where a small amount of copper component is present in the reaction solution.
  • the invention has been completed.
  • the method for producing silver particles of the present invention is a method for producing silver particles in which a silver compound solution, a protective agent, and a reducing agent solution are mixed and reduced in a reaction tank. And one or more substances (copper component) selected from the group consisting of copper ions.
  • the suitable form of the manufacturing method of the silver particle of this invention is a pre-copper component, a silver compound solution, a protective agent, a reducing agent solution, a mixed solution of a silver compound solution and a protective agent, and a mixing of a reducing agent solution and a protective agent. It is added to at least one selected from the group consisting of solutions.
  • the total addition amount of one or more selected from the group consisting of the copper, the copper compound and the copper ions is 1 to 1 in terms of copper with respect to silver in the reaction solution. It is characterized by being carried out in a state of containing 2000 ppm.
  • a preferred embodiment of the method for producing the silver particles is characterized in that the reduction reaction is performed at 40 to 80 ° C.
  • a preferred embodiment of the method for producing the silver particles is characterized in that the protective agent is one or more containing at least one of carbon, nitrogen, and oxygen.
  • a preferred embodiment of the method for producing silver particles is characterized in that the protective agent has a boiling point of 250 ° C. or lower.
  • a preferred embodiment of the method for producing the silver particles is characterized in that the functional group of the protective agent is one or more selected from the group consisting of a carboxyl group and an amino group.
  • the powder composed of the silver particles of the present invention (the term “powder” in this specification is used when a numerical value given when measuring physical properties is given as an average value of a plurality of particles), 1 to 1000 ppm of copper, the arithmetic average value of the particle diameter measured from the TEM image is 1 to 100 nm, and the powder has a specific surface area of 5 to 40 m 2 / g measured by the BET method.
  • the preferred form of the silver particles is characterized in that the coefficient of variation of the particle diameter measurement value is less than 30%.
  • a preferred form of the silver particles is characterized in that the protective agent has a boiling point of 250 ° C. or lower.
  • the preferred form of the silver particles is characterized by the presence of a protective agent containing at least one of carbon, nitrogen, and oxygen.
  • the protective agent is made of an organic carboxylic acid or a derivative thereof and has 3 to 8 carbon atoms.
  • the dispersion of the present invention is characterized by containing the silver particles of the present invention.
  • FIG. 4 is a TEM image obtained by photographing the particles produced in Example 1 at 174,000 times.
  • 4 is a TEM image obtained by photographing the particles produced in Example 8 at 174,000 times.
  • 4 is a TEM image obtained by photographing the particles produced in Example 11 at 174,000 times.
  • the method for producing silver particles of the present invention is characterized in that copper is present in the reaction system in a method for producing silver particles in which a silver compound solution, a protective agent, and a reducing agent solution are mixed and reduced in a reaction vessel.
  • a copper component means that any one or more of copper, a copper compound, and a copper ion exist.
  • the step of causing the copper component to exist in the mixed solution before the silver in the solution is reduced to silver by the reaction with the reducing agent is referred to as a copper addition step.
  • the copper addition step may include, for example, an operation of increasing the liquid temperature of the reaction solution containing copper after copper is present in the reaction system.
  • the reduction reaction is performed in a state where the copper component is present in the reaction solution, the effect is exhibited. In order to ensure uniformity, it is preferable that it be present before the reduction reaction.
  • the form of addition is not particularly limited, but it is more preferable that copper acting in the liquid is in an ionic state.
  • the copper component is added at the stage of the raw material solution before the reduction reaction such as a silver compound solution, a protective agent, a reducing agent solution, a mixed solution of the silver compound solution and the protective agent, and a mixed solution of the reducing agent solution and the protective agent. It may be added to one or more of the raw material solutions, or may be from the start of the reduction reaction after mixing the raw material solutions to the end thereof. However, in some cases, the reduction reaction may be completed in a short time of several minutes. Therefore, when adding during the reduction reaction, it is recommended to select a substance having a weak reducing power. In the present invention, the completion of the reaction means the time when the unreduced silver reaction does not occur when the reducing agent is added to the solution sampled from the reaction solution.
  • the form of added copper is not limited at all.
  • any form of powder, foil, or lump may be used under the condition that copper is eluted as ions.
  • the amount of the copper component added varies depending on the reaction scale, but the effect is saturated when it exceeds a certain amount. Therefore, the upper limit of the addition amount of the copper component is not particularly determined. Therefore, the presence of copper is not required more than necessary, and at most, it should be less than 2000 ppm, preferably less than 1000 ppm with respect to the entire liquid.
  • the silver particle concerning this invention can also be provided as a powder form through a drying process. Therefore, the silver particle in this specification includes the meaning of the powder when it is made into a dry form.
  • Copper contained in the silver powder formed by the method according to the present application is in the range of 1 to 1000 ppm. If it is less than 1 ppm, it can be said that it is not produced by the method according to the present invention, but if it is prepared by a wet method, the particle size becomes non-uniform. On the other hand, if it exceeds 1000 ppm, it indicates that the substitution of copper and silver in the liquid is insufficient, and even if the particle size is uniform, it may adversely affect the conductivity, which is preferable. Absent. In order to obtain pure silver, it is necessary that sufficient substitution is performed. Therefore, the remaining copper content is 1 to 1000 ppm, preferably 1 to 500 ppm, more preferably 1 to 300 ppm.
  • the said silver compound solution means what melt
  • the functional groups constituting the particles according to the present invention those having a so-called high affinity property that is easily compatible with the surface of the silver particles are preferably used.
  • Specific examples include a carboxyl group and an amino group.
  • the silver particles according to the present invention can be used as a conductive dispersion liquid or a paste mixed in a solvent or the like. At this time, in order to achieve high conductivity, it is preferable to have a high purity with as few impurities as possible.
  • the surfactant constituting the surface has a low boiling point. Specifically, it is preferably 250 ° C. or lower, more preferably 200 ° C. or lower, and still more preferably 150 ° C. or lower.
  • the protective agent in the present invention is not particularly limited as long as it has the above characteristics, but examples include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, sorbic acid, lactic acid, succinic acid, hexyl. Examples include amine, octylamine, hexamethylenediamine and the like.
  • the addition amount of the protective agent is preferably 0.1 to 4.0 in terms of a molar ratio to silver (number of moles of protective agent molecule / number of moles of silver). If it is less than 0.1, the amount of the protective agent is too small with respect to silver, so that a large number of particles may be condensed.
  • the ratio of the addition amount of the protective agent / silver is preferably in the range of 0.5 to 3.0, more preferably 1.0 to 2.0.
  • the reducing agent is not particularly limited as long as it can reduce silver ions to silver, and sodium borohydride, hydrazine, L-ascorbic acid, hydroquinone, gallic acid, formalin, phosphine, which have been widely used conventionally. Gluconic acid and derivatives thereof can be used.
  • the amount of the reducing agent added is preferably in the range of 1.0 to 9.0 in terms of equivalent to silver. If it is less than 1.0, there is a possibility that unreduction occurs, and if it exceeds 9.0, the amount of the reducing agent is too large and the reaction becomes excessively fast, so that the condensed particles increase and finally the particle size is increased. This is not preferable because the variation may increase.
  • the reducing agent solution may further contain a protective agent solubilizer.
  • a protective agent solubilizer This is for dissolving the protective agent when the protective agent that can be used in the production method of the present invention has poor solubility in a solvent.
  • the protective agent does not dissolve in the reducing agent solution and exists non-uniformly, the reaction may become non-uniform. Therefore, it is preferable to add the protective agent dissolving agent to dissolve the protective agent.
  • the type of the protective agent solubilizer varies depending on the type of the protective agent, but when the protective agent is an acid, ammonia or the like can be used. Further, the minimum amount necessary for dissolving the protective agent is sufficient.
  • the method for producing the silver particles is preferably performed within a range of 40 to 80 ° C.
  • the temperature is lower than 40 ° C.
  • the degree of supersaturation of silver increases, so that excessive nucleation occurs and primary particles become excessively fine.
  • the primary particle size is small, the cohesive force becomes strong, and the coagulation of the particles proceeds, leading to variations in the particle size.
  • the reduction is insufficient to cause reduction, and thus unreduction may occur.
  • the temperature exceeds 80 ° C. the reaction is too early, so that the particles may be fused together before being sufficiently protected by the protective agent, resulting in an increase in aggregated particles and accompanying particle size variation.
  • the reduction reaction is carried out at 40 to 80 ° C.” means that each of the solutions to be introduced into the reaction vessel may be heated to 40 to 80 ° C., or the solution is first brought to 40 to 80 ° C. in the reaction vessel. A method of heating and putting another solution at 40 to 80 ° C. may be performed.
  • the particle diameter of silver particles means the primary particle diameter measured by a measurement method described later from a TEM image.
  • the silver particles according to the present invention preferably have an average primary particle diameter in the range of 1 to 100 nm. When the average value of the primary particle diameters is less than 1 nm, it is difficult to prevent the occurrence of particle aggregation because the cohesive force of the particles is too strong. Further, when it exceeds 100 nm, the low-temperature sinterability deteriorates, so that it may be unsuitable for metal wiring applications where the silver particles of the present invention are expected to be used.
  • the specific surface area of the silver particle powder of the present invention measured by the BET method is 5 to 40 m 2 / g, preferably 15 to 40 m 2 / g, more preferably 20 to 30 m 2 / g.
  • the specific surface area of the silver particles produced by the production method of the present invention is remarkably increased by adding a copper component during production. Although the cause of this is unknown, it was found that the reaction rate was remarkably increased by comparing the reaction with and without the addition of copper. This suggests the possibility of acting as a catalyst.
  • the specific surface area of the silver particle powder can be adjusted by the amount of copper component added during production.
  • the viscosity is adjusted to suit the application and printing method.
  • the viscosity of the dispersion is greatly influenced by the specific surface area of the particle powder.
  • the specific surface area of the particle powder is large, the amount of solvent in contact with the particle surface increases, so that the amount of solvent not in contact with the particle surface decreases and the viscosity increases.
  • the surface area of the particle powder is small, the amount of the solvent in contact with the particle surface decreases, so that the amount of free solvent increases and the viscosity decreases.
  • the production method for easily obtaining silver particle powders having various specific surface areas as in the present invention has an advantage that it can easily cope with the adjustment of the dispersion viscosity suitable for various applications.
  • the specific surface area of the particle powder can be adjusted by a conventional method such as adjustment of the reducing agent amount and reaction temperature without using the production method of the present invention.
  • a dry silver particle powder having a specific surface area of 5 m 2 / g or more was not obtained even by such a change in reaction conditions.
  • it becomes an undesirable silver particle such as changing to the shape, or depending on the reaction conditions there is a risk of bumping, and it is necessary to take countermeasures each time, so changing the reaction conditions It is better to keep fine adjustments.
  • a coefficient of variation which is a value obtained by dividing the standard deviation value of the primary average particle diameter generally measured from the TEM image by the average value, is used as an index.
  • the coefficient of variation is less than 35%. If this value is 35% or more, it indicates that the variation in particle diameter is large, which is not preferable. Preferably it is less than 30%.
  • the silver particles according to the present invention by adopting the above-described configuration, the silver particles exhibit excellent properties at low temperature sintering.
  • the bulk resistance value of silver is 1.6 ⁇ ⁇ cm
  • the use of the particles according to the present invention makes it possible to take a resistance value approximate to this value even when the firing temperature is about 250 ° C.
  • the dispersion liquid of the present invention refers to a liquid in which the silver particles of the present invention are dispersed in a solvent.
  • the powder can be redispersed in various solvents.
  • the dispersion solvent that can be used in this case include water, alcohol, polyol, glycol ether, 1-methylpyrrolidinone, pyridine, terpineol, butyl carbitol, butyl carbitol acetate, texanol, and phenoxypropanol.
  • the binder is a necessary element for imparting dispersion independence to the particles, it is necessary to have at least an affinity for the solvent and the particles. Further, no matter how high the dispersibility is, it does not meet the object of the present invention unless it is discharged out of the system during sintering. That is, the decomposition or volatilization temperature is more preferably selected to be 250 ° C. or lower. If it has at least the above-mentioned property, it can be suitably used regardless of whether it is commercially available organic or inorganic. Moreover, you may use together not only a single kind.
  • organic binder acrylic resin, polyester resin, epoxy resin, phenol resin, phenoxy resin, DAP resin, urethane resin, fluororesin, polyimide resin, polyamide resin, silicone resin, polyolefin resin, ethyl cellulose and polyvinyl Alcohol or the like can be added, and silica sol, alumina sol, zirconia sol, titania sol, or the like can be used as the inorganic binder.
  • acrylic resins include BR-102, BR-105, BR-117, BR-118, BR-1122, MB-3058 (manufactured by Mitsubishi Rayon Co., Ltd.), Alflon UC-3000, Alflon UG-4010, Alflon UG-4070.
  • any commercially available one may be used as long as it has an affinity for the particle surface and also has an affinity for the dispersion medium. Moreover, you may use together not only a single kind.
  • Dispersants include fatty acid salts (soap), ⁇ -sulfo fatty acid ester salts (MES), alkylbenzene sulfonates (ABS), linear alkylbenzene sulfonates (LAS), alkyl sulfates (AS), alkyl ether sulfates Low molecular weight anionic (anionic) compounds such as salt (AES) and alkyl sulfate triethanol, fatty acid ethanolamide, polyoxyethylene alkyl ether (AE), polyoxyethylene alkylphenyl ether (APE), sorbitol, sorbitan Nonionic compounds, low molecular weight cationic (cationic) compounds such as alkyltrimethylammonium salts, dialkyldimethylammonium chlorides, alkylpyridinium chlorides, alkylcarboxyl betaines, sulfobetas Low molecular amphoteric compounds such as styrene and lecithin
  • Florene DOPA-15B Florene DOPA-17 (manufactured by Kyoeisha Chemical Co., Ltd.), Solplus AX5, Solplus TX5, Solsperse 9000, Solsperse 12000, Solsperse 17000, Solsperse 20000, Solsperse 21000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000, Solsperse 32000, Solsperse 35100, Solsperse 54000, Sol Six 250, (manufactured by Nippon Lubrizol Corporation), EFKA4008, EFKA4009, EFKA4010, EFKA4015, EFKA4046, EFKA4047, EFKA4060, EFKA7440E, EFKA7440E , EFKA4400, EFKA4401, EFKA4402, EFKA4403, EFKA4300, EFKA4330, EFKA4340, EFKA6220
  • any known method can be employed under the condition that the mechanical dispersion treatment does not involve significant modification of particles.
  • Specific examples include ultrasonic dispersion, a disper, a three-roll mill, a ball mill, a bead mill, a twin-screw kneader, and a self-revolving stirrer, and these can be used alone or in combination.
  • image analysis software (A Image-kun (registered trademark) manufactured by Asahi Kasei Engineering Co., Ltd.) was used. This image analysis software identifies individual particles by color shading. For a 174,000 times TEM image, the “particle brightness” is “dark”, the “noise removal filter” is “present”, “ The primary particle average diameter was measured by performing circular particle analysis under the conditions of “20” for the “round threshold” and “50” for the “overlap degree”. In addition, when there were many condensed particles and irregular shaped particles in the TEM image, it was determined that measurement was impossible.
  • Hydrochloric acid is added to a solution that is free from cloudiness and suspended matter to produce silver chloride. Thereafter, the mixture was separated into solid and liquid by filtration to separate the silver chloride and the filtrate, and the filtrate was analyzed for the amount of copper using ICP-MS (AGILENT 7500i manufactured by Agilent Technologies).
  • TAP density measurement The measurement was performed using the measurement method described in JP-A-2007-263860.
  • the silver particle powder was pasted and coated on a glass substrate.
  • the coated glass substrate was baked with a dryer (manufactured by Yamato Scientific Co., Ltd.) at the temperatures and times shown in the examples and comparative examples.
  • the volume resistance value per 1 ⁇ m thickness of the fired film was measured using a resistivity meter (Loresta GP manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the film thickness was measured by a surface roughness meter (Surfcom 1500D manufactured by Tokyo Seimitsu Co., Ltd.). ) was used to calculate the volume resistance value of the film.
  • Example 1 In Examples 1 to 7, a 5 L reaction vessel was used as the reaction vessel. In addition, a stirring bar with a blade was installed at the center of the reaction tank for stirring. A thermometer for monitoring the temperature was installed in the reaction tank, and a nozzle was provided so that nitrogen could be supplied to the solution from the bottom.
  • hexanoic acid manufactured by Wako Pure Chemical Industries, Ltd.
  • a protective agent corresponding to a molar ratio of 1.98 with respect to silver
  • 23.9 g (corresponding to 4.82 equivalents of silver) of a 50% by mass hydrazine hydrate (manufactured by Otsuka Chemical Co., Ltd.) aqueous solution as a reducing agent was added to obtain a reducing agent solution.
  • an aqueous silver nitrate solution prepared by dissolving 33.8 g of silver nitrate crystals (manufactured by Wako Pure Chemical Industries, Ltd.) in 180 g of water was prepared, and this was used as an aqueous silver salt solution.
  • copper nitrate trihydrate manufactured by Wako Pure Chemical Industries, Ltd.
  • the addition of copper nitrate trihydrate is adjusted by preparing a copper nitrate trihydrate aqueous solution having a known concentration in advance and adding a diluted solution thereof. Further, the temperature of the silver salt aqueous solution was adjusted to 60 ° C., the same as the reducing agent solution in the reaction vessel.
  • an aqueous silver salt solution was added to the reducing agent solution by mixing at once and a reduction reaction was started. At this time, the color of the slurry immediately changed from the end of the addition. Stirring was performed continuously and aged for 10 minutes in that state. Then, stirring is stopped, solid-liquid separation is performed by suction filtration, and after washing with pure water until the electrical conductivity of the washing waste liquid is less than 2.0 ⁇ S / cm, by drying at 40 ° C. for 12 hours, A fine silver particle powder was obtained. In addition, since the powder obtained has high sensitivity to heat, drying at a temperature higher than this temperature may result in massive silver.
  • Example 2 Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 5 ppm based on silver in terms of copper.
  • Example 3 Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 10 ppm with respect to silver in terms of copper.
  • the prepared silver particle-containing dispersion was coated on a slide glass using an applicator. Then, it baked for 30 minutes at 150 degreeC using the dryer (made by Yamato Scientific Co., Ltd.). Moreover, the sample baked for 30 minutes at 200 degreeC was also produced, and each volume resistance value was measured.
  • Example 4 The silver particle production process of Example 3 was repeated except that the copper source added to the aqueous silver salt solution was changed to cuprous oxide.
  • Example 5 Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 100 ppm with respect to silver in terms of copper.
  • Example 6 Example 5 was repeated except that the copper source added to the aqueous silver salt solution was changed to copper powder.
  • Example 7 Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 1000 ppm with respect to silver in terms of copper.
  • Example 8 In Examples 8 to 13, a 200 L reaction vessel was used as the reaction vessel. A stir bar, a thermometer, and a nitrogen nozzle were installed in the same manner as the 5 L reaction tank. First, 137 kg of water was put into the reaction tank, and nitrogen was passed from the lower part at a rate of 20 L / min for 600 seconds in order to remove the remaining oxygen. Thereafter, nitrogen was supplied from the upper part of the reaction tank at a rate of 20 L / min to make the inside of the reaction tank a nitrogen atmosphere. And temperature was adjusted, stirring so that the solution temperature in a reaction tank might be 60 degreeC. Then, 282.3 g of ammonia water containing 28% by mass as ammonia was added to the reaction vessel, and then stirred for 1 minute to make the solution uniform.
  • an aqueous silver nitrate solution in which 1350.3 g of silver nitrate crystals (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 7200 g of water was prepared, and this was used as an aqueous silver salt solution.
  • 0.0325 g of copper nitrate trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) (corresponding to 10 ppm of silver in terms of copper) was added.
  • the temperature of the silver salt aqueous solution was adjusted to 60 ° C., the same as the reducing agent solution in the reaction vessel.
  • the silver salt aqueous solution was added to the reducing agent solution at once and mixed to start the reduction reaction. Stirring was performed continuously and aged for 10 minutes in that state. Thereafter, stirring is stopped, solid-liquid separation by a filter press, washing with pure water until the electric conductivity of the washing liquid becomes less than 2.0 ⁇ S / cm, and after drying at 40 ° C. for 12 hours or more, fine silver Particle powder was obtained.
  • the obtained fine silver particle powder was added to a solvent or the like to prepare a dispersion.
  • 1.0 g of fine silver particle powder, 10.0 g of butyl carbitol acetate (manufactured by Wako Pure Chemical Industries, Ltd.), and 0.1 g of DisperBYK2020 (manufactured by Big Chemie Japan) as a dispersant were weighed. They were mixed in a test tube and dispersed with an ultrasonic disperser for 10 minutes. As a result, it was uniformly dispersed and no precipitate was observed on the bottom of the test tube. In addition, no precipitate was seen on the bottom of the test tube after standing for 24 hours, and the redispersibility was good.
  • Example 9 Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 20 ppm based on silver in terms of copper.
  • Example 10 Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 50 ppm based on silver in terms of copper.
  • Example 11 Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 100 ppm based on silver in terms of copper.
  • Example 12 Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 300 ppm based on silver in terms of copper.
  • Example 13 Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 500 ppm based on silver in terms of copper.
  • Example 1 Example 1 was repeated except that copper nitrate trihydrate was not added to the aqueous silver salt solution. The change of the color of the reaction slurry was completed about 30 seconds after the addition was completed.
  • Example 8 was repeated except that copper nitrate trihydrate was not added to the aqueous silver salt solution.
  • Example 3 (Comparative Example 3) Example 1 was repeated except that the amount of copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 6000 ppm based on silver in terms of copper.
  • Example 1 (Comparative Example 4) Example 1 was repeated except that the amount of copper nitrate trihydrate aqueous solution added to the aqueous silver salt solution was changed to an amount of 60000 ppm based on silver in terms of copper.
  • Example 1 Example 1 was repeated except that nickel nitrate hexahydrate aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of copper nitrate trihydrate to add an amount of 100 ppm in terms of nickel.
  • nickel nitrate hexahydrate aqueous solution manufactured by Wako Pure Chemical Industries, Ltd.
  • Example 6 (Comparative Example 6) Example 1 was repeated except that an iron (III) nitrate nonahydrate aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of copper nitrate trihydrate to add an amount of 100 ppm in terms of iron. It was.
  • an iron (III) nitrate nonahydrate aqueous solution manufactured by Wako Pure Chemical Industries, Ltd.
  • Comparative Example 7 After completion of the reduction reaction of Comparative Example 1, an aqueous solution of copper nitrate trihydrate was added to the reaction slurry in an amount of 3000 ppm with respect to silver in terms of copper, and stirring was continued for 5 minutes. Thereafter, stirring was stopped and filtration and washing were performed.
  • Comparative Example 8 Comparative Example 1 was repeated except that the amount of hydrazine hydrate of the reducing agent was changed to an amount that was 9.6 equivalents with respect to silver. Immediately after the start of the reduction reaction, the color change of the reaction slurry was completed, and it was confirmed that the reaction was complete.
  • Reaction scales of Examples and Comparative Examples additives added at the time of production and their addition amount, Cu content contained in the silver particle powder after the reaction, BET specific surface area of the dried silver particle powder, TAP density, Table 1 shows the TEM diameter, the coefficient of variation, and the volume resistance value of the silver film.
  • 1 to 3 show TEM images of Examples 1, 3 and 5, and
  • FIG. 4 shows a TEM image of Comparative Example 1. The magnification of all TEM photographs is 174,000 times. Note that the arrows on the lower right of the photographs in FIGS. 1 to 9 all represent 100 nm.
  • FIG. 10 is a graph showing the relationship between the amount of added Cu and BET for the examples and comparative examples separately for the 5L reaction and the 200L reaction.
  • Example 1 Comparative Example 1 and FIG. 10 in Table 1.
  • the vertical axis represents BET and the horizontal axis represents the amount of Cu added to Ag.
  • White circles and white triangles represent the results of Examples prepared in 5 L and 200 L reaction vessels, respectively.
  • the black circles and black triangles are comparative examples in 5 L and 200 L reaction tanks, respectively. Specifically, the black circle mark is Comparative Example 1 and the black triangle mark is Comparative Example 2.
  • Example 1 Even in Example 1 in which 1 ppm of Cu was added, the BET was 7 m 2 / g or more higher than the comparative example in which Cu was not added. In other words, it can be seen that the BET of the silver particle powder is increased when the comparative example Cu is added to the example and reacted. Moreover, since the same effect was acquired also by addition of copper powder (Example 6) and cuprous oxide (Example 4), it turns out that the effect of this invention is acquired irrespective of the form of the copper component to add. . Moreover, the effect appeared notably from the addition of 1 ppm of Cu, and was saturated around 10 ppm.
  • the relationship between the amount of copper component added and BET has a gentler slope than that in the case of 5 L reaction. This is very preferable from a manufacturing point of view. That is, as described above, when the silver particle powder having a desired BET is prepared by controlling the amount of copper component added, the control range of the amount of copper component added is widened in the 200L reaction. It is considered possible to obtain silver particles.
  • Comparative Examples 3 and 4 were obtained by adding 6000 ppm (0.6% by mass) and 60000 ppm (6% by mass), respectively, of the copper component. In the silver particles thus obtained, the amount of copper contained in the silver particles was It has become very much. When the silver particles of Comparative Examples 3 and 4 are made into a silver film, it is considered that this is because the resistance value is deteriorated.
  • Comparative Examples 5 and 6 a nickel component and an iron component were added instead of the copper component, respectively, but the effect as in the present invention was not obtained. It turns out that it is necessary to add a copper component in the manufacturing method concerning this invention.
  • Comparative Example 7 a copper component was added after completion of the reduction reaction, but the effect as in the present invention was not obtained. In the manufacturing method concerning this invention, it turns out that it is necessary to add a copper component before completion
  • Comparative Example 8 and FIG. 9 when Comparative Example 8 and FIG. 9 are seen, it can be seen that a large number of coarse particles are generated, although the reduction reaction is accelerated by increasing the amount of the reducing agent. From this, it can be seen that the reduction reaction is not simply accelerated, and the presence of the copper component is necessary for the particle size distribution and dispersibility.
  • the copper component was previously mixed with the silver component and then mixed with the reducing agent solution. Therefore, since the copper component was present in the mixed solution from the time when the reduction reaction was started, the end point of the reduction reaction was judged from the color change of the reaction slurry. However, even if the color change of the reaction slurry is completed, the reduction reaction itself may not be completed yet. Therefore, even when the reduction reaction is performed only with the silver compound solution, the protective agent, and the reducing agent solution, and the color change of the reaction slurry is completed, the effect of the present invention can be obtained by adding the copper component.
  • the production method of the present invention can easily produce silver particles similar to the small scale even in a large scale reaction, it is excellent in mass productivity. Further, the silver particles according to the present invention have a small variation in particle diameter and can be redispersed in various solvents, and therefore are suitable for dispersions used for metal wiring applications.

Abstract

Provided is a method suitable for the simple, mass production of nanoparticles having a uniform grain size, and silver particles produced by the same production method. One or more selected from the group consisting of copper, copper compounds, and copper ions is added prior to completion of the reduction reaction during the silver particle reaction in which a silver compound solution, protector, and reducing agent solution are mixed and reduction is performed.  As a result, regardless of the reaction scale, it is possible to produce particles having a uniform grain size by a reaction in which silver particles are obtained such that the average grain size in the solution is 1 to 100 nm.

Description

銅を含有する銀粒子及びその製造方法とそれを用いた分散液Silver particles containing copper, method for producing the same, and dispersion using the same
　本発明は、電子デバイスなどの配線や電極等に好適に使用できる銀粒子、銀粒子含有分散液、及び該銀粒子の製造方法に関する。 The present invention relates to a silver particle, a silver particle-containing dispersion, and a method for producing the silver particle that can be suitably used for wiring and electrodes of electronic devices.
　ナノオーダーの粒子径を持つ粒子は、ミクロンオーダー以上の粒子と比べて特異な性質を持つことが一般的によく知られており、その性質を生かした利用方法の検討がなされてきている。例えば、電気・電子機器業界では各種デバイスの小型化のため、ナノ粒子のサイズや低温焼結性を生かした基板上への微細配線を形成することの検討が行われている。 It is generally well known that particles having a nano-order particle size have unique properties compared to particles of micron-order or larger, and studies have been made on how to use them. For example, in the electrical and electronic equipment industry, in order to reduce the size of various devices, studies are being made on forming fine wiring on a substrate taking advantage of the size of nanoparticles and low-temperature sintering.
　例示した以外にも多種多様な用途で利用することが検討されているナノ粒子であるが、その製造法は大別して、気相法と液相法の２パターンが知られている。気相法による製造は一般的に真空条件下で作成されることが多いため、装置などの初期投資コストが高くなることや、また大量生産に向かないことがデメリットとして挙げられている。また、液相法の場合は大量生産に向いているが、反応初期と終了付近時での液性の違い、また反応槽内での液性のバラつきといった要因から得られる粒子の大きさ、あるいは形状にバラつきが起こることがあるため、結果として粒度分布が広くなりやすいという問題点がある。 The nanoparticles are being studied for use in a wide variety of applications other than those exemplified, but their production methods are roughly classified into two patterns, a gas phase method and a liquid phase method. Since manufacturing by a vapor phase method is generally often performed under vacuum conditions, it has been cited as a disadvantage that the initial investment cost of an apparatus or the like is high and it is not suitable for mass production. In the case of the liquid phase method, it is suitable for mass production, but the particle size obtained from factors such as the difference in liquidity at the beginning and near the end of the reaction, and the variation in liquidity in the reaction tank, or Since the shape may vary, there is a problem that the particle size distribution tends to become wide as a result.
　従来の液相法による合成では、例えば銀粒子を液相反応で得る場合、銀塩溶液と還元剤溶液を直接接触させることで反応を開始する場合が多い。ところが、このような反応を用いる場合、反応は急激に起こるため、反応が完了するまでの時間は極端な場合、秒単位となってしまうことがある。このような反応では、液を添加した部分から局所的に反応が進行してしまうことがある。その場合には、得られる粒子の形態を均一なものとするのが困難であるといえる。それでも粒子径の比較的均一なものを得るには、高度に反応状態の制御を行うことや、あるいは還元剤として比較的緩慢なものを選択し、反応速度を落とすことで、均一化を図るという試みがなされてきた。 In the synthesis by the conventional liquid phase method, for example, when silver particles are obtained by a liquid phase reaction, the reaction is often started by directly contacting a silver salt solution and a reducing agent solution. However, when such a reaction is used, the reaction occurs abruptly, and therefore the time until the reaction is completed may be in seconds when it is extreme. In such a reaction, the reaction may proceed locally from the portion where the liquid is added. In that case, it can be said that it is difficult to make the shape of the obtained particles uniform. Still, in order to obtain particles with a relatively uniform particle size, the reaction state is highly controlled, or a relatively slow reducing agent is selected, and the reaction rate is reduced, thereby achieving uniformity. Attempts have been made.
　加えてナノ粒子には、粒子凝集の問題がある。ナノ粒子はその特徴である粒子径の微細さに起因して、粒子間の凝集力が従来知られているミクロンオーダーやサブミクロンオーダーの粒子に比較して大きく、粒子そのものの反応性が高いことから、粒子の凝集と結合が同時に起こる、いわゆる凝結の状態に陥ることがあり、そのような状態に陥ればもはやナノ粒子として期待される性質を呈さないことがある。 In addition, nanoparticles have the problem of particle aggregation. Nanoparticles are characterized by their fine particle size, and their cohesion between particles is larger than conventionally known micron-order and sub-micron-order particles, and the particles themselves are highly reactive. Therefore, there is a case where particles are aggregated and bonded at the same time, so that a so-called coagulation state occurs, and if such a state is reached, the properties expected as nanoparticles may no longer be exhibited.
　こうした事態を解決するため、様々な検討がなされてきた。具体的には、反応形態そのものを変更することや、前述のように還元を緩慢な条件下で行い、反応系を比較的均一なものとすることである。前者の例としては、例えば特許文献１のように従来行われていたバッチ式の反応から連続式の反応に変更することが挙げられる。当該文献の技術によれば、連続式にすることで混合状態を常に一定なものとすることができる。そのため、従来のバッチ式反応に見られる局所的な濃度のばらつきが小さくなり、反応が反応系のいずれの部分でも均一になるため、結果として均一な粒径を呈する銀微粒子を得ることができている。 Various studies have been made to solve this situation. Specifically, the reaction form itself is changed, or the reduction is performed under slow conditions as described above to make the reaction system relatively uniform. As an example of the former, for example, it is possible to change from a batch-type reaction conventionally performed as in Patent Document 1 to a continuous-type reaction. According to the technique of the said literature, a mixing state can always be made constant by making it a continuous type. Therefore, the local concentration variation seen in the conventional batch reaction is reduced, and the reaction is uniform in any part of the reaction system. As a result, silver fine particles having a uniform particle size can be obtained. Yes.
　また、後者の例としては、特許文献２のように銀塩溶液と弱い還元剤を保護剤の存在下で混合した後、徐々に加温していくことによって還元を開始する方法が試みられている。この場合、還元剤の還元力が緩慢であるため、原料溶液に還元剤を接触させただけでは反応は開始されない。還元を開始させるためには、系外から熱を加えて反応を開始させる必要がある。すなわち、還元が開始される温度までに反応槽内の液を均一なものとするよう調整することもできる。その結果、還元開始温度に達した時点から反応槽全域において、ほぼ均一に還元が開始されるようになるため、粒子径のバラつきが少ない粉末を得ることができている。 As an example of the latter, a method of starting reduction by mixing a silver salt solution and a weak reducing agent in the presence of a protective agent and gradually heating the mixture as in Patent Document 2 is attempted. Yes. In this case, since the reducing agent has a slow reducing power, the reaction is not started only by bringing the reducing agent into contact with the raw material solution. In order to start the reduction, it is necessary to start the reaction by applying heat from outside the system. That is, the liquid in the reaction vessel can be adjusted to be uniform by the temperature at which the reduction is started. As a result, since the reduction starts almost uniformly in the entire reaction tank from the time when the reduction start temperature is reached, a powder with little variation in particle diameter can be obtained.
特開２００４－０６８０７２号明細書JP 2004-068072 A 特開２００７－１４６２７９号明細書Japanese Patent Application Laid-Open No. 2007-146279
　前述した特許文献１～２はいずれも粒度の揃ったナノ粒子が得られていることから、期待されていた粒子径の均一化、という課題に関しては満足するものである。しかし、特許文献１の場合、その特徴でもある連続式反応であるために、生産管理の面で劣る部分が発生してしまうことがある。具体的には、通常大量の生産を検討した場合、様々な要因から不具合が発生することがある。そうした場合、連続式反応の場合は異常原因がつかみづらい。また、粒子がナノオーダーのものの場合には、不具合をｉｎ－ｓｉｔｕで確認することが難しい。その結果として不良条件で連続製造してしまうことになり、多くの製造物が廃棄などの処分となる場合がある。このことからわかるように、不具合が発生した場合に出来る限り損失を少なくするという観点から言えばバッチ式反応のほうが好ましい。また、特許文献１の方法により、単純にバッチ式の反応としても、該文献の比較例の記載から明らかなとおり、粒子径が不均一なものとなるため、当初期待されている粒子径の均一性向上効果が得られない結果になってしまう。よって、この方式を用いて生産性と粒子径の均一さを同時に満足するにはやや難がある。 The above-mentioned Patent Documents 1 and 2 both satisfy the expected problem of uniform particle diameter because nanoparticles having a uniform particle size are obtained. However, in the case of patent document 1, since it is the continuous reaction which is the feature, the part inferior in terms of production management may occur. Specifically, when considering mass production in general, problems may occur due to various factors. In such a case, it is difficult to grasp the cause of abnormality in the case of continuous reaction. In addition, when the particles are nano-order, it is difficult to confirm the defect in-situ. As a result, continuous production is performed under defective conditions, and many products may be disposed of such as disposal. As can be seen from this, the batch reaction is preferable from the viewpoint of reducing the loss as much as possible when a failure occurs. Moreover, even if it is simply a batch-type reaction by the method of Patent Document 1, the particle diameter is non-uniform as is apparent from the description of the comparative example of the document, so that the initially expected particle diameter is uniform. As a result, the effect of improving the property cannot be obtained. Therefore, it is somewhat difficult to satisfy productivity and uniformity of particle size at the same time using this method.
　また、特許文献２の場合、故意に還元力の弱い還元剤を用いて、所定温度まで昇温して徐々に還元を進めるため、反応時間が数時間と長くなってしまい生産能力が低いものとなってしまうものであった。また、温度をきっかけとして還元を進める反応であるため、反応槽が数百リットル以上などの大容量となった場合には反応槽内での温度バラつきが大きくなり、粒子径が不揃いとなる虞がある。 Further, in the case of Patent Document 2, since a reducing agent having a weak reducing power is intentionally heated to a predetermined temperature and gradually reduced, the reaction time becomes several hours and the production capacity is low. It was something that would end up. Moreover, since the reaction proceeds with the reduction triggered by the temperature, when the reaction tank has a large capacity of several hundred liters or more, the temperature variation in the reaction tank becomes large, and the particle size may be uneven. is there.
　また溶媒を所望のものに変更するには、いわゆる溶媒の置換作業を行う必要があった。更に得られる溶媒における銀濃度は１．５～９．５％といった比較的希薄なものであるため、利用に適した濃度とするためには濃縮が必要となり、その限外濾過による濃縮工程に時間がかかるという問題があった。そのため、量産性の観点からはさらなる改善が必要なものであった。 Also, in order to change the solvent to a desired one, it was necessary to perform a so-called solvent replacement operation. Furthermore, since the silver concentration in the obtained solvent is relatively dilute, such as 1.5 to 9.5%, concentration is necessary to obtain a concentration suitable for use. There was a problem that it took. Therefore, further improvement is necessary from the viewpoint of mass productivity.
　こうした従来技術の有する問題点に鑑み、本発明は粒子径の揃ったナノ粒子の簡便且つ大量生産に適した製造方法及び該製造方法によって製造した銀粒子およびその集合体である粉末を提供することを目的とした。 In view of such problems of the prior art, the present invention provides a production method suitable for simple and mass production of nanoparticles having a uniform particle diameter, silver particles produced by the production method, and powder that is an aggregate thereof. Aimed.
　本発明者らは上記目的を達成するために鋭意研究を重ねた結果、反応液中に銅成分を微量に存在させた状態で還元反応を行えば、上記目的を達成できうることを見出し、本発明の完成に至った。 As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved if a reduction reaction is performed in a state where a small amount of copper component is present in the reaction solution. The invention has been completed.
　すなわち、本発明の銀粒子の製造方法は、反応槽中にて銀化合物溶液と保護剤と還元剤溶液とを混合して還元する銀粒子の製造方法において、還元反応終了前に銅、銅化合物及び銅イオンからなる群より選ばれる１種以上の物質（銅成分）を添加することを特徴とする。 That is, the method for producing silver particles of the present invention is a method for producing silver particles in which a silver compound solution, a protective agent, and a reducing agent solution are mixed and reduced in a reaction tank. And one or more substances (copper component) selected from the group consisting of copper ions.
　また、本発明の銀粒子の製造方法の好適形態は、前銅成分を、銀化合物溶液、保護剤、還元剤溶液、銀化合物溶液と保護剤の混合溶液及び、還元剤溶液と保護剤の混合溶液からなる群より選ばれる少なくとも１つに添加することを特徴とする。 Moreover, the suitable form of the manufacturing method of the silver particle of this invention is a pre-copper component, a silver compound solution, a protective agent, a reducing agent solution, a mixed solution of a silver compound solution and a protective agent, and a mixing of a reducing agent solution and a protective agent. It is added to at least one selected from the group consisting of solutions.
　また、前記銀粒子の製造方法の好適形態は、前記銅、銅化合物及び銅イオンからなる群より選ばれる１種以上の合計添加量が、銅換算で前記反応液中の銀に対して１～２０００ｐｐｍ含有された状態で行われることを特徴とする。 Further, in a preferred embodiment of the method for producing the silver particles, the total addition amount of one or more selected from the group consisting of the copper, the copper compound and the copper ions is 1 to 1 in terms of copper with respect to silver in the reaction solution. It is characterized by being carried out in a state of containing 2000 ppm.
　また、前記銀粒子の製造方法の好適形態は、前記還元反応を４０～８０℃で行うことを特徴とする。 Further, a preferred embodiment of the method for producing the silver particles is characterized in that the reduction reaction is performed at 40 to 80 ° C.
　また、前記銀粒子の製造方法の好適形態は、前記保護剤が炭素、窒素、酸素のいずれか一種以上を含む１種以上であることを特徴とする。 Further, a preferred embodiment of the method for producing the silver particles is characterized in that the protective agent is one or more containing at least one of carbon, nitrogen, and oxygen.
　また、前記銀粒子の製造方法の好適形態は、前記保護剤の沸点が２５０℃以下であることを特徴とする。 Further, a preferred embodiment of the method for producing silver particles is characterized in that the protective agent has a boiling point of 250 ° C. or lower.
　また、前記銀粒子の製造方法の好適形態は、前記保護剤が持つ官能基が、カルボキシル基及びアミノ基からなる群より選ばれる１種以上であることを特徴とする。 Further, a preferred embodiment of the method for producing the silver particles is characterized in that the functional group of the protective agent is one or more selected from the group consisting of a carboxyl group and an amino group.
　また、本発明の銀粒子からなる粉末（本明細書における「粉末」という用語は、物理特性を測定する際に与えられる数値が複数個の粒子の平均値として与えられる場合に使用する）は、１～１０００ｐｐｍの銅を含み、ＴＥＭ像から計測される粒子径の算術平均値が１～１００ｎｍであり、ＢＥＴ法で測定した粉末の比表面積が５～４０ｍ2／ｇである銅を含むことを特徴とする。 In addition, the powder composed of the silver particles of the present invention (the term “powder” in this specification is used when a numerical value given when measuring physical properties is given as an average value of a plurality of particles), 1 to 1000 ppm of copper, the arithmetic average value of the particle diameter measured from the TEM image is 1 to 100 nm, and the powder has a specific surface area of 5 to 40 m 2 / g measured by the BET method. Features.
　また、前記銀粒子の好適形態は、粒子径計測値の変動係数が３０％未満であることを特徴とする。 The preferred form of the silver particles is characterized in that the coefficient of variation of the particle diameter measurement value is less than 30%.
　また、前記銀粒子の好適形態は、前記保護剤の沸点が２５０℃以下であることを特徴とする。 Also, a preferred form of the silver particles is characterized in that the protective agent has a boiling point of 250 ° C. or lower.
　また、前記銀粒子の好適形態は、炭素、窒素、酸素のいずれか一種以上を含む保護剤が存在することを特徴とする。 The preferred form of the silver particles is characterized by the presence of a protective agent containing at least one of carbon, nitrogen, and oxygen.
　また、前記保護剤は有機カルボン酸もしくはその誘導体からなり、炭素数が３～８であることを特徴とする。 The protective agent is made of an organic carboxylic acid or a derivative thereof and has 3 to 8 carbon atoms.
　また、本発明の分散液は、前記本発明の銀粒子を含むことを特徴とする。 Further, the dispersion of the present invention is characterized by containing the silver particles of the present invention.
　本明細書で開示する方法を採用することにより、溶液中における平均粒子径が１～１００ｎｍであるような銀粒子を得る反応操作においても、反応スケールに関わらず粒子径の均整なものを得ることができるようになる。 By adopting the method disclosed in this specification, even in a reaction operation for obtaining silver particles having an average particle size of 1 to 100 nm in a solution, a uniform particle size can be obtained regardless of the reaction scale. Will be able to.
実施例１で作製した粒子を１７４０００倍で撮影したＴＥＭ像。4 is a TEM image obtained by photographing the particles produced in Example 1 at 174,000 times. 実施例３で作製した粒子を１７４０００倍で撮影したＴＥＭ像。TEM image which image | photographed the particle | grains produced in Example 3 by 174000 times. 実施例５で作製した粒子を１７４０００倍で撮影したＴＥＭ像。TEM image which image | photographed the particle | grains produced in Example 5 by 174,000 times. 比較例１で作製した粒子を１７４０００倍で撮影したＴＥＭ像。TEM image which image | photographed the particle | grains produced in the comparative example 1 by 174000 times. 実施例８で作製した粒子を１７４０００倍で撮影したＴＥＭ像。4 is a TEM image obtained by photographing the particles produced in Example 8 at 174,000 times. 実施例１１で作製した粒子を１７４０００倍で撮影したＴＥＭ像。4 is a TEM image obtained by photographing the particles produced in Example 11 at 174,000 times. 比較例５で作製した粒子を１７４０００倍で撮影したＴＥＭ像。TEM image which image | photographed the particle | grains produced in the comparative example 5 by 174000 times. 比較例６で作製した粒子を１７４０００倍で撮影したＴＥＭ像。TEM image which image | photographed 174,000 times the particle | grains produced in the comparative example 6. FIG. 比較例８で作製した粒子を１７４０００倍で撮影したＴＥＭ像。TEM image which image | photographed the particle | grains produced in the comparative example 8 by 174000 times. 実施例及び比較例で行った５Ｌ反応に関する銅成分添加量とＢＥＴ比表面積の関係を示したグラフ。The graph which showed the relationship between the copper component addition amount and BET specific surface area regarding 5L reaction performed by the Example and the comparative example.
　以下に、本発明の好適な実施形態について説明する。 Hereinafter, preferred embodiments of the present invention will be described.
　本発明の銀粒子製造方法は、反応槽中にて銀化合物溶液と保護剤と還元剤溶液とを混合して還元する銀粒子の製造方法において、該反応系中に銅を存在させることを特徴とする。なお、本明細書においては銅成分とは、銅、銅化合物及び銅イオンのいずれか若しくは複数が存在することをいう。 The method for producing silver particles of the present invention is characterized in that copper is present in the reaction system in a method for producing silver particles in which a silver compound solution, a protective agent, and a reducing agent solution are mixed and reduced in a reaction vessel. And In addition, in this specification, a copper component means that any one or more of copper, a copper compound, and a copper ion exist.
　本発明では、溶液中の銀が還元剤との反応により、銀に還元されるまでの間に銅成分を混合液中に存在させるようにする工程を銅添加工程という。銅添加工程は、例えば銅を反応系中に存在させた後、銅の存在する反応液の液温を上昇させる操作を含んでも良い。 In the present invention, the step of causing the copper component to exist in the mixed solution before the silver in the solution is reduced to silver by the reaction with the reducing agent is referred to as a copper addition step. The copper addition step may include, for example, an operation of increasing the liquid temperature of the reaction solution containing copper after copper is present in the reaction system.
　本発明の製造方法においては、反応液中に銅成分が存在した状態で還元反応が行われれば効果を発揮するため、添加する時期は還元反応終了前であれば良いことになるが、反応の均一性を確保するためには、還元反応に至るまでの間に存在させておくことが好ましい。その添加の形態は、別段制限されるものではないが、液中において作用する銅はイオンの状態となっていることがより好ましい。 In the production method of the present invention, if the reduction reaction is performed in a state where the copper component is present in the reaction solution, the effect is exhibited. In order to ensure uniformity, it is preferable that it be present before the reduction reaction. The form of addition is not particularly limited, but it is more preferable that copper acting in the liquid is in an ionic state.
　銅成分の添加は、銀化合物溶液、保護剤、還元剤溶液、銀化合物溶液と保護剤の混合溶液及び、還元剤溶液と保護剤の混合溶液のような還元反応実施前の原料溶液の段階で該原料溶液の１つ以上に添加しても良いし、該原料溶液を混合して還元反応を始めてから終了するまでの間でも良い。ただし、還元反応は場合により、数分間という短時間で完了してしまうこともあるため、還元反応中に添加する場合には、還元力が弱いものを選択して実施することが推奨される。なお、本発明において反応終了とは反応溶液中からサンプリングした液に還元剤を添加した際に未還元の銀反応が起こらなくなった時点のことを言う。 The copper component is added at the stage of the raw material solution before the reduction reaction such as a silver compound solution, a protective agent, a reducing agent solution, a mixed solution of the silver compound solution and the protective agent, and a mixed solution of the reducing agent solution and the protective agent. It may be added to one or more of the raw material solutions, or may be from the start of the reduction reaction after mixing the raw material solutions to the end thereof. However, in some cases, the reduction reaction may be completed in a short time of several minutes. Therefore, when adding during the reduction reaction, it is recommended to select a substance having a weak reducing power. In the present invention, the completion of the reaction means the time when the unreduced silver reaction does not occur when the reducing agent is added to the solution sampled from the reaction solution.
　最終的な生成物において、銅はほぼ存在が確認されないことから見て、銅は粒子に取り込まれることは必須の構成要件ではない。すなわち、反応メカニズムには不明なところが多いが、本発明において銅は、反応時において反応液中に存在することで足るといえる。従って、添加される銅の形態はなんら制限は受けない。例えば塊状での添加であれば、銅がイオンとして溶出するような条件下において、粉、箔、塊のいずれの形態であっても良い。ただし、この場合には粉、箔、塊は反応終了後に分離できうる手法を講じておくことが、不純物の混入を抑制するという観点からは好ましい。 In view of the fact that copper is hardly present in the final product, it is not an indispensable constituent requirement for copper to be incorporated into the particles. That is, although there are many unclear points in the reaction mechanism, it can be said that it is sufficient that copper is present in the reaction solution during the reaction in the present invention. Therefore, the form of added copper is not limited at all. For example, if it is added in the form of a lump, any form of powder, foil, or lump may be used under the condition that copper is eluted as ions. However, in this case, it is preferable from the viewpoint of suppressing the contamination of impurities that a powder, foil, and lump can be separated after the reaction.
　本発明においては、銅成分の添加量は反応スケールによっても異なるが一定量以上になると効果が飽和する。そのため、銅成分の添加量の上限は特に決められるものではない。そのため、必要以上に銅の存在は必要とはされず、高くとも液全体に対し２０００ｐｐｍ未満、好ましくは１０００ｐｐｍ未満とするのがよい。 In the present invention, the amount of the copper component added varies depending on the reaction scale, but the effect is saturated when it exceeds a certain amount. Therefore, the upper limit of the addition amount of the copper component is not particularly determined. Therefore, the presence of copper is not required more than necessary, and at most, it should be less than 2000 ppm, preferably less than 1000 ppm with respect to the entire liquid.
　銅は、銀よりも卑な金属であるため、銅と銀が共存する液中において、銅はイオン形態の方が安定である。従って、最終生成物の銀粒子中には溶液中に添加された銅はほとんど含有されない。なお、本発明にかかる銀粒子は乾燥工程を経ることにより、粉末状として提供することもできる。従って、本明細書における銀粒子とは、乾燥形態にしたときの粉末の意味も包含する。 Since copper is a base metal rather than silver, copper is more stable in ionic form in a liquid in which copper and silver coexist. Therefore, the copper added to the solution is hardly contained in the silver particles of the final product. In addition, the silver particle concerning this invention can also be provided as a powder form through a drying process. Therefore, the silver particle in this specification includes the meaning of the powder when it is made into a dry form.
　本願に従う方法により形成される銀粉末に含まれる銅は、１～１０００ｐｐｍの範囲になる。１ｐｐｍ未満の場合には、本発明に従う方法では製造していないと言うことができるが、湿式法で作成した場合には粒径は不均一なものとなってしまう。一方、１０００ｐｐｍを超える場合には、液中における銅と銀の置換が不十分であることを示し、粒径が均整なものであったとしても、導電性に悪影響を与える可能性があるので好ましくない。純粋な銀とするためには、十分な置換が行われていることが必要であるため、残存する銅含有量は１～１０００ｐｐｍ、好ましくは１～５００ｐｐｍ、より好ましくは１～３００ｐｐｍである。 Copper contained in the silver powder formed by the method according to the present application is in the range of 1 to 1000 ppm. If it is less than 1 ppm, it can be said that it is not produced by the method according to the present invention, but if it is prepared by a wet method, the particle size becomes non-uniform. On the other hand, if it exceeds 1000 ppm, it indicates that the substitution of copper and silver in the liquid is insufficient, and even if the particle size is uniform, it may adversely affect the conductivity, which is preferable. Absent. In order to obtain pure silver, it is necessary that sufficient substitution is performed. Therefore, the remaining copper content is 1 to 1000 ppm, preferably 1 to 500 ppm, more preferably 1 to 300 ppm.
　以下、本発明の原料溶液について説明する。前記銀化合物溶液とは銀化合物を溶媒に溶解させたものを言う。前記銀化合物の種類は溶媒に応じて溶解するものを適宜選択すれば良く、例えば溶媒が水であれば硝酸銀を好適に使用することができる。 Hereinafter, the raw material solution of the present invention will be described. The said silver compound solution means what melt | dissolved the silver compound in the solvent. What is necessary is just to select the thing of the said silver compound which melt | dissolves suitably according to a solvent, for example, if a solvent is water, silver nitrate can be used conveniently.
　本発明に従う粒子を構成する官能基は、銀粒子表面に対してなじみやすい、いわゆる親和性の高い性質を有するものが好適に利用される。具体的にはカルボキシル基、アミノ基などが例示できる。 As the functional groups constituting the particles according to the present invention, those having a so-called high affinity property that is easily compatible with the surface of the silver particles are preferably used. Specific examples include a carboxyl group and an amino group.
　本発明にかかる銀粒子の使用形態としては、溶剤等に混入させて導電性分散液、あるいはペーストとして使用することがあげられる。この時、導電性の高いものとするには、できるだけ不純物の少ない高純度のものとすることが好ましい。 As a usage form of the silver particles according to the present invention, it can be used as a conductive dispersion liquid or a paste mixed in a solvent or the like. At this time, in order to achieve high conductivity, it is preferable to have a high purity with as few impurities as possible.
　高純度の金属膜を形成するには、不純物の混入を可能な限り少なくする必要がある。そのため、保護剤は焼成後の導電膜組成物中において、ほぼ消失し確認されない程度にすることが望まれる。したがって、表面を構成する界面活性剤の沸点は低いことが好ましい。具体的には２５０℃以下、より好ましくは２００℃以下、さらに好ましくは１５０℃以下が良い。 In order to form a high-purity metal film, it is necessary to minimize the contamination of impurities. Therefore, it is desired that the protective agent is almost disappeared and not confirmed in the conductive film composition after firing. Therefore, it is preferable that the surfactant constituting the surface has a low boiling point. Specifically, it is preferably 250 ° C. or lower, more preferably 200 ° C. or lower, and still more preferably 150 ° C. or lower.
　本発明における保護剤は前記の特性を兼ね揃えるものであれば特に制限はないが、例としては、ブタン酸、ペンタン酸、ヘキサン酸、ヘプタン酸、オクタン酸、ソルビン酸、乳酸、コハク酸、ヘキシルアミン、オクチルアミン、ヘキサメチレンジアミンなどが挙げられる。また、保護剤の添加量は銀に対するモル比（保護剤分子モル数／銀モル数）で０．１～４．０が好ましい。０．１未満である場合、銀に対して保護剤の量が少なすぎるため、粒子同士の凝結が多数発生する可能性がある。 The protective agent in the present invention is not particularly limited as long as it has the above characteristics, but examples include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, sorbic acid, lactic acid, succinic acid, hexyl. Examples include amine, octylamine, hexamethylenediamine and the like. The addition amount of the protective agent is preferably 0.1 to 4.0 in terms of a molar ratio to silver (number of moles of protective agent molecule / number of moles of silver). If it is less than 0.1, the amount of the protective agent is too small with respect to silver, so that a large number of particles may be condensed.
　また、４．０を超える場合は銀の周囲を被覆する保護剤が多くなりすぎることを示す。このことは最終的に生成する銀組成物中において、不純物が多く残存する虞が高いことを示し、高純度の銀膜を得にくくなる虞があるので好ましくない。従って、保護剤の添加量／銀の比は、好ましくは０．５～３．０、更に好ましくは１．０～２．０の範囲である。 Also, if it exceeds 4.0, it indicates that the protective agent covering the periphery of silver is too much. This indicates that there is a high possibility that many impurities remain in the finally produced silver composition, and it is difficult to obtain a high-purity silver film, which is not preferable. Therefore, the ratio of the addition amount of the protective agent / silver is preferably in the range of 0.5 to 3.0, more preferably 1.0 to 2.0.
　また、前記還元剤は銀イオンを銀にまで還元できるものであれば特に制限はなく、従来から広く使用されている水素化ホウ素ナトリウム、ヒドラジン、Ｌ－アスコルビン酸、ヒドロキノン、没食子酸、ホルマリン、ホスフィン、グルコン酸やそれらの誘導体などを用いることができる。 The reducing agent is not particularly limited as long as it can reduce silver ions to silver, and sodium borohydride, hydrazine, L-ascorbic acid, hydroquinone, gallic acid, formalin, phosphine, which have been widely used conventionally. Gluconic acid and derivatives thereof can be used.
　還元剤の添加量は銀に対する当量にして１．０～９．０の範囲が好ましい。１．０未満の場合未還元が発生する可能性があり、９．０を超える場合は還元剤量が多すぎるため反応が過剰に早くなることで、凝結粒子が増加し最終的に粒子径のバラつきが大きくなる可能性があるので好ましくない。 The amount of the reducing agent added is preferably in the range of 1.0 to 9.0 in terms of equivalent to silver. If it is less than 1.0, there is a possibility that unreduction occurs, and if it exceeds 9.0, the amount of the reducing agent is too large and the reaction becomes excessively fast, so that the condensed particles increase and finally the particle size is increased. This is not preferable because the variation may increase.
　また、前記還元剤溶液には、更に保護剤の溶解剤を含むことができる。これは、本発明の製造方法で使用できる保護剤が溶媒への溶解性に乏しい場合に前記保護剤を溶解させるためのものである。保護剤が還元剤溶液中で溶解せず不均一に存在する場合、反応が不均一になる可能性があるため、保護剤溶解剤を添加して保護剤を溶解させることが好ましい。前記保護剤溶解剤の種類は保護剤の種類によっても変わるが、保護剤が酸の場合はアンモニアなどを使用することができる。また、添加量は保護剤を溶解させるのに必要な最低量あれば十分である。 Further, the reducing agent solution may further contain a protective agent solubilizer. This is for dissolving the protective agent when the protective agent that can be used in the production method of the present invention has poor solubility in a solvent. When the protective agent does not dissolve in the reducing agent solution and exists non-uniformly, the reaction may become non-uniform. Therefore, it is preferable to add the protective agent dissolving agent to dissolve the protective agent. The type of the protective agent solubilizer varies depending on the type of the protective agent, but when the protective agent is an acid, ammonia or the like can be used. Further, the minimum amount necessary for dissolving the protective agent is sufficient.
　また、前記銀粒子の製造方法は４０～８０℃の範囲内で行われることが好ましい。４０℃未満の場合、銀の過飽和度が上がることから、過剰な核発生が生じてしまい、１次粒子の過剰な微粒子化が進むことになる。一般的に一次粒子径が小さい場合には凝集力が強くなるため、粒子同士の凝結が進んでしまうことから、粒子径のバラつきにつながる。また、他の反応条件によっては、還元を生じさせるには不十分なものとなってしまうため、未還元が発生してこともある。また、８０℃を超える場合は反応が早すぎるため保護剤によって十分に保護される前に粒子同士が融着し合い、凝結粒子の増加とそれに伴う粒子径のバラつきが発生することがある。 Further, the method for producing the silver particles is preferably performed within a range of 40 to 80 ° C. When the temperature is lower than 40 ° C., the degree of supersaturation of silver increases, so that excessive nucleation occurs and primary particles become excessively fine. In general, when the primary particle size is small, the cohesive force becomes strong, and the coagulation of the particles proceeds, leading to variations in the particle size. In addition, depending on other reaction conditions, the reduction is insufficient to cause reduction, and thus unreduction may occur. Further, when the temperature exceeds 80 ° C., the reaction is too early, so that the particles may be fused together before being sufficiently protected by the protective agent, resulting in an increase in aggregated particles and accompanying particle size variation.
　「還元反応を４０～８０℃で行う」とは、反応槽中に投入する溶液をそれぞれ４０～８０℃に加熱しておいてもよいし、最初に反応槽中で４０～８０℃に溶液を加熱しておき、そこに４０～８０℃の他の溶液を入れるといった方法を行ってもよい。 “The reduction reaction is carried out at 40 to 80 ° C.” means that each of the solutions to be introduced into the reaction vessel may be heated to 40 to 80 ° C., or the solution is first brought to 40 to 80 ° C. in the reaction vessel. A method of heating and putting another solution at 40 to 80 ° C. may be performed.
　次に本発明の製造法で作製できる銀粒子について詳細に説明する。 Next, the silver particles that can be produced by the production method of the present invention will be described in detail.
　本発明の製造法によれば、反応スケールに関わらず粒子径の揃ったナノオーダーの銀粒子を得ることができる。ここで、銀粒子の粒子径とはＴＥＭ像から後述する測定法によって測定される１次粒子径を意味する。本発明にかかる銀粒子は前記１次粒子径の平均値が１～１００ｎｍの範囲内にあることが好ましい。この１次粒子径の平均値が１ｎｍ未満である場合、粒子の凝集力が強すぎるため粒子凝結の発生を防ぐことが困難となる。また、１００ｎｍを超える場合は低温焼結性が悪化するため、本発明の銀粒子が使用されることが予測される金属配線用途などにおいて不適なものとなることが考えられる。 According to the production method of the present invention, nano-order silver particles having a uniform particle diameter can be obtained regardless of the reaction scale. Here, the particle diameter of silver particles means the primary particle diameter measured by a measurement method described later from a TEM image. The silver particles according to the present invention preferably have an average primary particle diameter in the range of 1 to 100 nm. When the average value of the primary particle diameters is less than 1 nm, it is difficult to prevent the occurrence of particle aggregation because the cohesive force of the particles is too strong. Further, when it exceeds 100 nm, the low-temperature sinterability deteriorates, so that it may be unsuitable for metal wiring applications where the silver particles of the present invention are expected to be used.
　また、本発明の銀粒子粉末をＢＥＴ法で測定した比表面積は５～４０ｍ2／ｇであり、好ましくは１５～４０ｍ2／ｇ、より好ましくは２０～３０ｍ2／ｇである。本発明の製造方法で作製した銀粒子は、製造時に銅成分を添加することによって比表面積が著しく増加する。この原因については不明であるが、銅を添加する場合としない場合の反応の様子を見比べると、その反応速度が著しく早くなっていることが分かった。このことから触媒的な働きをしている可能性が考えられる。 The specific surface area of the silver particle powder of the present invention measured by the BET method is 5 to 40 m 2 / g, preferably 15 to 40 m 2 / g, more preferably 20 to 30 m 2 / g. The specific surface area of the silver particles produced by the production method of the present invention is remarkably increased by adding a copper component during production. Although the cause of this is unknown, it was found that the reaction rate was remarkably increased by comparing the reaction with and without the addition of copper. This suggests the possibility of acting as a catalyst.
　また、銀粒子粉末の比表面積は製造時に添加する銅成分量によって調整することができる。銀粒子を分散液化する際などには、用途や印刷法に合った粘度に調整することが行われる。分散液の粘度は粒子粉末の比表面積が大きく影響する。例えば、粒子粉末の比表面積が大きい場合には粒子表面と接する溶媒量が増加するため、該粒子表面と接さない溶媒量が少なくなって粘度が増加する。また、粒子粉末の表面積が小さい場合には粒子表面と接する溶媒量が減少するため、フリーな溶媒量が多くなるため粘度が低下する。 Also, the specific surface area of the silver particle powder can be adjusted by the amount of copper component added during production. For example, when the silver particles are dispersed, the viscosity is adjusted to suit the application and printing method. The viscosity of the dispersion is greatly influenced by the specific surface area of the particle powder. For example, when the specific surface area of the particle powder is large, the amount of solvent in contact with the particle surface increases, so that the amount of solvent not in contact with the particle surface decreases and the viscosity increases. In addition, when the surface area of the particle powder is small, the amount of the solvent in contact with the particle surface decreases, so that the amount of free solvent increases and the viscosity decreases.
　一般的には粉末の表面積を調整すること以外にも、粘度調整剤の添加や溶媒添加量の調整などで分散液の粘度調整に対応しているが、粘度調整剤の添加は前述の理屈と同じく、残存する不純物が多くなるため導電性阻害要因となり、金属膜にした際の体積抵抗値が高くなってしまうことがある。このような可能性を排除するため、粒子粉末の比表面積の変化で調整できることが好ましい。その点で、本発明のように様々な比表面積の銀粒子粉末を簡便に得られる製造方法は、様々な用途に適した分散液粘度の調整に容易に対応できるというメリットを有している。 In general, in addition to adjusting the surface area of the powder, it is possible to adjust the viscosity of the dispersion by adding a viscosity modifier or adjusting the amount of solvent added. Similarly, since the amount of remaining impurities increases, it becomes a conductivity impeding factor, and the volume resistance value when the metal film is formed may increase. In order to eliminate such a possibility, it is preferable to be able to adjust by changing the specific surface area of the particle powder. In that respect, the production method for easily obtaining silver particle powders having various specific surface areas as in the present invention has an advantage that it can easily cope with the adjustment of the dispersion viscosity suitable for various applications.
　また、粒子粉末の比表面積調整に関しては、本発明の製造方法を用いずとも、還元剤量や反応温度の調整など従来から行われているような方法によっても粒子粉末の比表面積を調整することが考えられるが、本発明者らの検討によれば、そのような反応条件の変更によっても、５ｍ2／ｇ以上の比表面積を有する乾燥銀粒子粉末は得られなかった。また、その都度液性が変化して形状まで変化するなどの望ましくない銀粒子となる場合や、反応条件によっては突沸する危険もあり、その都度対策を取る必要があるため、反応条件の変更はあくまで微調整程度に留めたほうが良い。 In addition, regarding the specific surface area adjustment of the particle powder, the specific surface area of the particle powder can be adjusted by a conventional method such as adjustment of the reducing agent amount and reaction temperature without using the production method of the present invention. However, according to the study by the present inventors, a dry silver particle powder having a specific surface area of 5 m 2 / g or more was not obtained even by such a change in reaction conditions. In addition, when the liquidity changes each time, it becomes an undesirable silver particle such as changing to the shape, or depending on the reaction conditions there is a risk of bumping, and it is necessary to take countermeasures each time, so changing the reaction conditions It is better to keep fine adjustments.
　ここで本発明の特性の一つである粒子径のバラつきに関して説明する。粒子径のバラつきについては、一般的にＴＥＭ像から測定される一次平均粒子径の標準偏差値を平均値で割った値である変動係数を指標に用いている。本発明にかかる銀粒子の場合、前記変動係数は３５％未満となる。この値が３５％以上だと、粒子径のバラつきが大きいことを示し好ましくない。好ましくは３０％未満である。 Here, the particle size variation which is one of the characteristics of the present invention will be described. Regarding the variation in the particle diameter, a coefficient of variation, which is a value obtained by dividing the standard deviation value of the primary average particle diameter generally measured from the TEM image by the average value, is used as an index. In the case of silver particles according to the present invention, the coefficient of variation is less than 35%. If this value is 35% or more, it indicates that the variation in particle diameter is large, which is not preferable. Preferably it is less than 30%.
　本発明に従う銀粒子においては上述の構成を採用することで、低温焼結性に優れた性質を呈するようになる。銀のバルク抵抗値は１．６μΩ・ｃｍであるが、本発明に従う粒子を採用することによって、焼成温度を２５０℃程度としても、この値に近似した抵抗値を取ることができるようになる。また、こうした性質を与えるためには、後述する分散液としたときの構成、とりわけ分散媒や添加剤の分解点や沸点に対しても配慮が必要であることは言うまでもない。 In the silver particles according to the present invention, by adopting the above-described configuration, the silver particles exhibit excellent properties at low temperature sintering. Although the bulk resistance value of silver is 1.6 μΩ · cm, the use of the particles according to the present invention makes it possible to take a resistance value approximate to this value even when the firing temperature is about 250 ° C. In order to give such properties, it goes without saying that consideration should be given to the structure of the dispersion described later, particularly the decomposition point and boiling point of the dispersion medium and additives.
　また、本発明の銀粒子製造方法によれば簡便に様々な比表面積の銀粒子粉末を作製することができるため、様々な用途、印刷法に対応できる分散液を作製することができる。本発明の分散液とは、本発明の銀粒子が、溶媒中に分散されている液体をいう。 Further, according to the silver particle production method of the present invention, silver particle powders having various specific surface areas can be easily produced, and therefore, dispersions that can be used for various applications and printing methods can be produced. The dispersion liquid of the present invention refers to a liquid in which the silver particles of the present invention are dispersed in a solvent.
　また、本発明の好適な実施形態によれば、反応後に凝集沈降するため濾過によって簡便に固液分離ができ、更にその粉末は様々な溶媒に再分散させることができる。この際に使用できる分散液溶媒としては、水、アルコール、ポリオール、グリコールエーテル、１－メチルピロリジノン、ピリジン、ターピネオール、ブチルカルビトール、ブチルカルビトールアセテート、テキサノール、フェノキシプロパノールなどが例示できる。 In addition, according to a preferred embodiment of the present invention, since it aggregates and settles after the reaction, it can be easily separated into solid and liquid by filtration, and the powder can be redispersed in various solvents. Examples of the dispersion solvent that can be used in this case include water, alcohol, polyol, glycol ether, 1-methylpyrrolidinone, pyridine, terpineol, butyl carbitol, butyl carbitol acetate, texanol, and phenoxypropanol.
　また分散液の分散性やチキソトロピー性などをより向上させるために、適宜分散液溶媒と共にバインダーや分散剤のいずれか、あるいはその両方を添加することも好適な形態を構成する。バインダーは、粒子に対して分散独立性を与えるために必要な要素となるので、溶剤並びに粒子との親和性を少なくとも有することが必要である。また、いくら分散性が高くなっても、焼結時に系外に排出されるものでなければ、本願発明の目的には合致しない。すなわち、分解もしくは揮散温度は２５０℃以下のものがより好適に選択される。少なくとも上述の性質を有していれば、市販の有機、無機を問わず好適に使用することができる。また、単独の種類のみならず、併用使用しても構わない。 In order to further improve the dispersibility and thixotropy of the dispersion, it is also possible to add a binder and / or a dispersant together with the dispersion solvent as appropriate. Since the binder is a necessary element for imparting dispersion independence to the particles, it is necessary to have at least an affinity for the solvent and the particles. Further, no matter how high the dispersibility is, it does not meet the object of the present invention unless it is discharged out of the system during sintering. That is, the decomposition or volatilization temperature is more preferably selected to be 250 ° C. or lower. If it has at least the above-mentioned property, it can be suitably used regardless of whether it is commercially available organic or inorganic. Moreover, you may use together not only a single kind.
　具体的にバインダーとしては、有機バインダーとして、アクリル樹脂、ポリエステル樹脂、エポキシ樹脂、フェノール樹脂、フェノキシ樹脂、ＤＡＰ樹脂、ウレタン樹脂、フッ素樹脂、ポリイミド樹脂、ポリアミド樹脂、シリコーン樹脂、ポリオレフィン樹脂、エチルセルロースおよびポリビニルアルコール等を添加することができ、無機バインダーとしては、シリカゾル、アルミナゾル、ジルコニアゾル、チタニアゾル等を使用することができる。 Specifically, as an organic binder, acrylic resin, polyester resin, epoxy resin, phenol resin, phenoxy resin, DAP resin, urethane resin, fluororesin, polyimide resin, polyamide resin, silicone resin, polyolefin resin, ethyl cellulose and polyvinyl Alcohol or the like can be added, and silica sol, alumina sol, zirconia sol, titania sol, or the like can be used as the inorganic binder.
　具体的名称を挙げると次のようなものが知られているが、上述の性質を有する場合には、本欄に記載のもの以外のものの使用を排除するものではない。アクリル樹脂としては、ＢＲ－１０２、ＢＲ－１０５、ＢＲ－１１７、ＢＲ－１１８、ＢＲ－１１２２、ＭＢ－３０５８（三菱レイヨン株式会社製）、アルフロンＵＣ－３０００、アルフロンＵＧ－４０１０、アルフロンＵＧ－４０７０、アルフロンＵＨ－２０４１、アルフロンＵＰ－１０２０、アルフロンＵＰ－１０２１、アルフロンＵＰ－１０６１（東亞合成株式会社製）、ポリエステル樹脂としては、バイロン２２０、バイロン５００、バイロンＵＲ１３５０（東洋紡績株式会社製）、マルキードＮｏ１（荒川化学工業株式会社製）、エポキシ樹脂としては、アデカレジンＥＰ－４０８８Ｓ、アデカレジンＥＰ－４９－２３（株式会社アデカ製）、８７１（ジャパンエポキシレジン株式会社製）、フェノール樹脂としては、レヂトップＰＬ－４３４８、レヂトップＰＬ－６３１７（群栄化学工業株式会社製）、フェノキシ樹脂としては、１２５６、４２７５（ジャパンエポキシレジン株式会社製）、タマノル３４０（荒川化学工業株式会社製）、ＤＡＰ樹脂としては、ダップＡ、ダップＫ（ダイソー株式会社製）、ウレタン樹脂としては、ミリオネートＭＳ－５０（日本ポリウレタン工業株式会社製）、エチルセルロースとしては、エトセルＳＴＡＮＤＡＲＤ４、エトセルＳＴＡＮＤＡＲＤ７、エトセルＳＴＡＮＤＡＲＤ２０、エトセルＳＴＡＮＤＡＲＤ１００（日進化成株式会社製）、ポリビニルアルコールとしては、ＲＳ－１７１３、ＲＳ－１７１７、ＲＳ－２１１７（株式会社クラレ製）といったものが例示できる。 The following are known as specific names. However, the use of anything other than those described in this section is not excluded if it has the above-mentioned properties. Examples of acrylic resins include BR-102, BR-105, BR-117, BR-118, BR-1122, MB-3058 (manufactured by Mitsubishi Rayon Co., Ltd.), Alflon UC-3000, Alflon UG-4010, Alflon UG-4070. Alflon UH-2041, Alflon UP-1020, Alflon UP-1021, Alflon UP-1061 (manufactured by Toagosei Co., Ltd.), polyester resins such as Byron 220, Byron 500, Byron UR1350 (Toyobo Co., Ltd.), Marquide No. 1 (made by Arakawa Chemical Co., Ltd.), as epoxy resin, Adeka Resin EP-4088S, Adeka Resin EP-49-23 (made by Adeka Co., Ltd.), 871 (made by Japan Epoxy Resin Co., Ltd.), as a phenol resin, Resitop L-4348, Resitop PL-6317 (manufactured by Gunei Chemical Industry Co., Ltd.), phenoxy resin, 1256, 4275 (manufactured by Japan Epoxy Resin Co., Ltd.), Tamanoru 340 (manufactured by Arakawa Chemical Industry Co., Ltd.), DAP resin , Dup A, Dup K (manufactured by Daiso Corporation), Millionate MS-50 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as urethane resin, and Ethose cellulose as STANDARD4, ETHELL STANDARD7, ETHELL STANDARD20, ETHELL STANDARD100 (Nippon Evolution Co., Ltd.) Examples of the polyvinyl alcohol include RS-1713, RS-1717, and RS-2117 (manufactured by Kuraray Co., Ltd.).
　また分散剤としても、粒子表面と親和性を有するとともに分散媒に対しても親和性を有するものであれば、市販汎用のものであっても足りる。また、単独の種類のみならず、併用使用しても構わない。 As the dispersant, any commercially available one may be used as long as it has an affinity for the particle surface and also has an affinity for the dispersion medium. Moreover, you may use together not only a single kind.
　分散剤としては、脂肪酸塩（石けん）、α－スルホ脂肪酸エステル塩（ＭＥＳ）、アルキルベンゼンスルホン酸塩（ＡＢＳ）、直鎖アルキルベンゼンスルホン酸塩（ＬＡＳ）、アルキル硫酸塩（ＡＳ）、アルキルエーテル硫酸エステル塩（ＡＥＳ）、アルキル硫酸トリエタノールといった低分子陰イオン性（アニオン性）化合物、脂肪酸エタノールアミド、ポリオキシエチレンアルキルエーテル（ＡＥ）、ポリオキシエチレンアルキルフェニルエーテル（ＡＰＥ）、ソルビトール、ソルビタンといった低分子非イオン系化合物、アルキルトリメチルアンモニウム塩、ジアルキルジメチルアンモニウムクロリド、アルキルピリジニウムクロリド、といった低分子陽イオン性（カチオン性）化合物、アルキルカルボキシルベタイン、スルホベタイン、レシチンといった低分子両性系化合物や、ナフタレンスルホン酸塩のホルマリン縮合物、ポリスチレンスルホン酸塩、ポリアクリル酸塩、ビニル化合物とカルボン酸系単量体の共重合体塩、カルボキシメチルセルロース、ポリビニルアルコールなどに代表される高分子水系分散剤、ポリアクリル酸部分アルキルエステル、ポリアルキレンポリアミンといった高分子非水系分散剤、ポリエチレンイミン、アミノアルキルメタクリレート共重合体といった高分子カチオン系分散剤が代表的なものであるが、本発明の粒子に好適に適用されるものであれば、ここに例示したような形態のもの以外の構造を有するものを排除しない。 Dispersants include fatty acid salts (soap), α-sulfo fatty acid ester salts (MES), alkylbenzene sulfonates (ABS), linear alkylbenzene sulfonates (LAS), alkyl sulfates (AS), alkyl ether sulfates Low molecular weight anionic (anionic) compounds such as salt (AES) and alkyl sulfate triethanol, fatty acid ethanolamide, polyoxyethylene alkyl ether (AE), polyoxyethylene alkylphenyl ether (APE), sorbitol, sorbitan Nonionic compounds, low molecular weight cationic (cationic) compounds such as alkyltrimethylammonium salts, dialkyldimethylammonium chlorides, alkylpyridinium chlorides, alkylcarboxyl betaines, sulfobetas Low molecular amphoteric compounds such as styrene and lecithin, formalin condensate of naphthalene sulfonate, polystyrene sulfonate, polyacrylate, copolymer salt of vinyl compound and carboxylic acid monomer, carboxymethyl cellulose, polyvinyl alcohol Typical examples are polymeric water-based dispersants such as polyacrylic acid partial alkyl esters and polyalkylene polyamines, and polymer cationic dispersants such as polyethyleneimine and aminoalkyl methacrylate copolymers. However, as long as it can be suitably applied to the particles of the present invention, those having a structure other than the ones exemplified here are not excluded.
　分散剤として、具体的名称を挙げると次のようなものが知られている。フローレンＤＯＰＡ－１５Ｂ、フローレンＤＯＰＡ－１７（共栄社化学株式会社製）、ソルプラスＡＸ５、ソルプラスＴＸ５、ソルスパース９０００、ソルスパース１２０００、ソルスパース１７０００、ソルスパース２００００、ソルスパース２１０００、ソルスパース２４０００、ソルスパース２６０００、ソルスパース２７０００、ソルスパース２８０００、ソルスパース３２０００、ソルスパース３５１００、ソルスパース５４０００、ソルシックス２５０、（日本ルーブリゾール株式会社製）、ＥＦＫＡ４００８、ＥＦＫＡ４００９、ＥＦＫＡ４０１０、ＥＦＫＡ４０１５、ＥＦＫＡ４０４６、ＥＦＫＡ４０４７、ＥＦＫＡ４０６０、ＥＦＫＡ４０８０、ＥＦＫＡ７４６２、ＥＦＫＡ４０２０、ＥＦＫＡ４０５０、ＥＦＫＡ４０５５、ＥＦＫＡ４４００、ＥＦＫＡ４４０１、ＥＦＫＡ４４０２、ＥＦＫＡ４４０３、ＥＦＫＡ４３００、ＥＦＫＡ４３３０、ＥＦＫＡ４３４０、ＥＦＫＡ６２２０、ＥＦＫＡ６２２５、ＥＦＫＡ６７００、ＥＦＫＡ６７８０、ＥＦＫＡ６７８２、ＥＦＫＡ８５０３（エフカアディディブズ社製）、アジスパーＰＡ１１１、アジスパーＰＢ７１１、アジスパーＰＢ８２１、アジスパーＰＢ８２２、アジスパーＰＮ４１１、フェイメックスＬ－１２（味の素ファインテクノ株式会社製）、ＴＥＸＡＰＨＯＲ－ＵＶ２１、ＴＥＸＡＰＨＯＲ－ＵＶ６１（コグニスジャパン株式会社製）、ＤｉｓｐｅｒＢＹＫ１０１、ＤｉｓｐｅｒＢＹＫ１０２、ＤｉｓｐｅｒＢＹＫ１０６、ＤｉｓｐｅｒＢＹＫ１０８、ＤｉｓｐｅｒＢＹＫ１１１、ＤｉｓｐｅｒＢＹＫ１１６、ＤｉｓｐｅｒＢＹＫ１３０、ＤｉｓｐｅｒＢＹＫ１４０、ＤｉｓｐｅｒＢＹＫ１４２、ＤｉｓｐｅｒＢＹＫ１４５、ＤｉｓｐｅｒＢＹＫ１６１、ＤｉｓｐｅｒＢＹＫ１６２、ＤｉｓｐｅｒＢＹＫ１６３、ＤｉｓｐｅｒＢＹＫ１６４、ＤｉｓｐｅｒＢＹＫ１６６、ＤｉｓｐｅｒＢＹＫ１６７、ＤｉｓｐｅｒＢＹＫ１６８、ＤｉｓｐｅｒＢＹＫ１７０、ＤｉｓｐｅｒＢＹＫ１７１、ＤｉｓｐｅｒＢＹＫ１７４、ＤｉｓｐｅｒＢＹＫ１８０、ＤｉｓｐｅｒＢＹＫ１８２、ＤｉｓｐｅｒＢＹＫ１９２、ＤｉｓｐｅｒＢＹＫ１９３、ＤｉｓｐｅｒＢＹＫ２０００、ＤｉｓｐｅｒＢＹＫ２００１、ＤｉｓｐｅｒＢＹＫ２０２０、ＤｉｓｐｅｒＢＹＫ２０２５、ＤｉｓｐｅｒＢＹＫ２０５０、ＤｉｓｐｅｒＢＹＫ２０７０、ＤｉｓｐｅｒＢＹＫ２１５５、ＤｉｓｐｅｒＢＹＫ２１６４、ＢＹＫ２２０Ｓ、ＢＹＫ３００、ＢＹＫ３０６、ＢＹＫ３２０、ＢＹＫ３２２、ＢＹＫ３２５、ＢＹＫ３３０、ＢＹＫ３４０、ＢＹＫ３５０、ＢＹＫ３７７、ＢＹＫ３７８、ＢＹＫ３８０Ｎ、ＢＹＫ４１０、ＢＹＫ４２５、ＢＹＫ４３０（ビックケミー・ジャパン株式会社製）、ディスパロン１７５１Ｎ、ディスパロン１８３１、ディスパロン１８５０、ディスパロン１８６０、ディスパロン１９３４、ディスパロンＤＡ－４００Ｎ、ディスパロンＤＡ－７０３－５０、ディスパロンＤＡ－７２５、ディスパロンＤＡ－７０５、ディスパロンＤＡ－７３０１、ディスパロンＤＮ－９００、ディスパロンＮＳ－５２１０、ディスパロンＮＶＩ－８５１４Ｌ、ヒップラードＥＤ－１５２、ヒップラードＥＤ－２１６、ヒップラードＥＤ－２５１、ヒップラードＥＤ－３６０（楠本化成株式会社）、ＦＴＸ－２０７Ｓ、ＦＴＸ－２１２Ｐ、ＦＴＸ－２２０Ｐ、ＦＴＸ－２２０Ｓ、ＦＴＸ－２２８Ｐ、ＦＴＸ－７１０ＬＬ、ＦＴＸ－７５０ＬＬ、フタージェント２１２Ｐ、フタージェント２２０Ｐ、フタージェント２２２Ｆ、フタージェント２２８Ｐ、フタージェント２４５Ｆ、フタージェント２４５Ｐ、フタージェント２５０、フタージェント２５１、フタージェント７１０ＦＭ、フタージェント７３０ＦＭ、フタージェント７３０ＬＬ、フタージェント７３０ＬＳ、フタージェント７５０ＤＭ、フタージェント７５０ＦＭ（株式会社ネオス製）、ＡＳ－１１００、ＡＳ－１８００、ＡＳ－２０００（東亞合成株式会社製）、カオーセラ２０００、カオーセラ２１００、ＫＤＨ－１５４、ＭＸ－２０４５Ｌ、ホモゲノールＬ－１８、ホモゲノールＬ－９５、レオドールＳＰ－０１０Ｖ、レオドールＳＰ－０３０Ｖ、レオドールＳＰ－Ｌ１０、レオドールＳＰ－Ｐ１０（花王株式会社製）、エバンＵ１０３、シアノールＤＣ９０２Ｂ、ノイゲンＥＡ－１６７、ブライサーフＡ２１９Ｂ、ブライサーフＡＬ（第一工業製薬株式会社製）、メガファックＦ－４７７、メガファック４８０ＳＦ、メガファックＦ－４８２、（ＤＩＣ株式会社製）、シルフェイスＳＡＧ５０３Ａ、ダイノール６０４（日信化学工業株式会社製）、ＳＮスパーズ２１８０、ＳＮスパーズ２１９０、ＳＮレベラーＳ－９０６（サンノプコ株式会社製）、Ｓ－３８６、Ｓ４２０（ＡＧＣセイミケミカル株式会社製）といったものが例示できる。 The following are known as specific dispersants. Florene DOPA-15B, Florene DOPA-17 (manufactured by Kyoeisha Chemical Co., Ltd.), Solplus AX5, Solplus TX5, Solsperse 9000, Solsperse 12000, Solsperse 17000, Solsperse 20000, Solsperse 21000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000, Solsperse 32000, Solsperse 35100, Solsperse 54000, Sol Six 250, (manufactured by Nippon Lubrizol Corporation), EFKA4008, EFKA4009, EFKA4010, EFKA4015, EFKA4046, EFKA4047, EFKA4060, EFKA7440E, EFKA7440E , EFKA4400, EFKA4401, EFKA4402, EFKA4403, EFKA4300, EFKA4330, EFKA4340, EFKA6220, EFKA6225, EFKA6700, EFKA6780, EFKA6782, EFKA11503, EFKA8503 Famex L-12 (manufactured by Ajinomoto Fine Techno Co., Ltd.), TEXAPHOR-UV21, TEXAPHOR-UV61 (manufactured by Cognis Japan Co., Ltd.), DisperBYK101, DisperBYK102, DisperBYK106, DisperBYK108, DisperBYK111, DisperBY 116, DisperBYK130, DisperBYK140, DisperBYK142, DisperBYK145, DisperBYK161, DisperBYK162, DisperBYK163, DisperBYK164, DisperBYK166, DisperBYK167, DisperBYK168, DisperBYK170, DisperBYK171, DisperBYK174, DisperBYK180, DisperBYK182, DisperBYK192, DisperBYK193, DisperBYK2000, DisperBYK2001, DisperBYK2020, DisperBYK2025, DisperBYK2050, DisperBYK2070, DisperBYK21 55, DisperBYK2164, BYK220S, BYK300, BYK306, BYK320, BYK322, BYK325, BYK330, BYK340, BYK350, BYK377, BYK378, BYK380N, BYK410, BYK430, BYK430 , Disparon 1860, Disparon 1934, Disparon DA-400N, Disparon DA-703-50, Disparon DA-725, Disparon DA-705, Disparon DA-7301, Disparon DN-900, Disparon NS-5210, Disparon NVI-8514L, Hip Lard ED-152, Hiprad ED- 16, Hiplard ED-251, Hiplard ED-360 (Enomoto Kasei Co., Ltd.), FTX-207S, FTX-212P, FTX-220P, FTX-220S, FTX-228P, FTX-710LL, FTX-750LL, FT 212P, Aftergent 220P, Aftergent 222F, Aftergent 228P, Aftergent 245F, Aftergent 245P, Aftergent 250, Aftergent 251, Aftergent 710FM, Aftergent 730FM, Aftergent 730LL, Aftergent 730LS, Aftergent 750DM, Aftergent 750FM (manufactured by Neos Co., Ltd.), AS-1100, AS-1800, AS-2000 (manufactured by Toagosei Co., Ltd.), Kaosela 2000, Kato -Sera 2100, KDH-154, MX-2045L, Homogenol L-18, Homogenol L-95, Rheodor SP-010V, Rheodor SP-030V, Rheodor SP-L10, Rheodor SP-P10 (manufactured by Kao Corporation), Evan U103, Cyanol DC902B, Neugen EA-167, BRYSURF A219B, BRYSURF AL (Daiichi Kogyo Seiyaku Co., Ltd.), Megafuck F-477, MegaFuck 480SF, MegaFuck F-482 (DIC Corporation), Sylface SAG503A, Dinol 604 (manufactured by Nissin Chemical Industry Co., Ltd.), SN spurs 2180, SN spurs 2190, SN leveler S-906 (manufactured by San Nopco), S-386, S420 (manufactured by AGC Seimi Chemical Co., Ltd.) Can be illustrated.
　また、分散液の調整時を適切な機械的な分散処理を用いることもできる。機械的分散処理には粒子の著しい改質を伴わないという条件下において、公知のいずれの方法も採用することが可能である。具体的には、超音波分散、ディスパー、三本ロールミル、ボールミル、ビーズミル、二軸ニーダー、自公転式攪拌機などが例示でき、これらは単独あるいは複数を併用して使用することもできる。 It is also possible to use an appropriate mechanical dispersion process when adjusting the dispersion. Any known method can be employed under the condition that the mechanical dispersion treatment does not involve significant modification of particles. Specific examples include ultrasonic dispersion, a disper, a three-roll mill, a ball mill, a bead mill, a twin-screw kneader, and a self-revolving stirrer, and these can be used alone or in combination.
　以下に本発明で用いた測定方法を説明する。 The measurement method used in the present invention will be described below.
　（ＴＥＭ像からの一次粒子径の平均値の測定）
　乾燥状態の銀粒子粉末２質量部をシクロヘキサン９６質量部とオレイン酸２質量部との混合溶液に添加し、超音波によって分散させた。分散溶液を支持膜付きＣｕマイクログリッドに滴下し、乾燥させることでＴＥＭ試料とした。作成したマイクログリッドを透過型電子顕微鏡（日本電子株式会社製ＪＥＭ－１００ＣＸＭａｒｋ－ＩＩ型）を使用し、１００ｋＶの加速電圧で、明視野で粒子を観察した像を、倍率３０，０００倍及び１７４，０００倍で撮影した。 (Measurement of average primary particle diameter from TEM image)
2 parts by mass of the dried silver particle powder was added to a mixed solution of 96 parts by mass of cyclohexane and 2 parts by mass of oleic acid and dispersed by ultrasonic waves. The dispersion solution was dropped on a Cu microgrid with a support film and dried to obtain a TEM sample. An image obtained by observing particles in a bright field using a transmission electron microscope (JEM-100CXMark-II type, manufactured by JEOL Ltd.) at a accelerating voltage of 100 kV was used for the created microgrid. Shot at 000x.
　一次粒子平均径の算出には、画像解析ソフト（旭化成エンジニアリング株式会社製Ａ像くん（登録商標））を用いた。この画像解析ソフトは色の濃淡で個々の粒子を識別するものであり、１７４，０００倍のＴＥＭ像に対して「粒子の明度」を「暗」、「雑音除去フィルタ」を「有」、「円形しきい値」を「２０」、「重なり度」を「５０」の条件で円形粒子解析を行って一次粒子平均径を測定した。なお、ＴＥＭ像中に凝結粒子や異形粒子が多数ある場合は、測定不能であるとした。 For the calculation of the average primary particle diameter, image analysis software (A Image-kun (registered trademark) manufactured by Asahi Kasei Engineering Co., Ltd.) was used. This image analysis software identifies individual particles by color shading. For a 174,000 times TEM image, the “particle brightness” is “dark”, the “noise removal filter” is “present”, “ The primary particle average diameter was measured by performing circular particle analysis under the conditions of “20” for the “round threshold” and “50” for the “overlap degree”. In addition, when there were many condensed particles and irregular shaped particles in the TEM image, it was determined that measurement was impossible.
　（１次粒子径からの変動係数の算出）
　上記の測定方法での１０００個以上での測定値から平均値、標準偏差を算出し、標準偏差を平均値で割った値を変動係数として算出した。 (Calculation of coefficient of variation from primary particle size)
An average value and a standard deviation were calculated from measured values of 1000 or more in the above measurement method, and a value obtained by dividing the standard deviation by the average value was calculated as a coefficient of variation.
　（銀粒子粉末中の銅含有量測定）
　銀成分が残留していると分析誤差が発生する可能性があるため、銀成分を除くため、以下の前処理を施した。３００ｍｌコニカルビーカーに銀粒子粉末１０ｇを入れ、次に硝酸溶液１５ｍｌを添加して銀粒子粉末を溶解させる。溶解した溶液を２５０℃に設定したホットプレート上で加熱し、蒸発乾固にならない程度まで濃縮する。濃縮された溶液を放冷した後、純水を添加する。溶液中に白濁や浮遊物がないことを確認する。もし溶液中に白濁や浮遊物がある場合には、なくなるまで硝酸添加、加熱濃縮、放冷の工程を繰り返す。白濁や浮遊物がない溶液に塩酸を添加し、塩化銀を生成する。その後濾過で固液分離して塩化銀と濾液を分別し、該濾液をＩＣＰ－ＭＳ（アジレントテクノロジー株式会社製ＡＧＩＬＥＮＴ７５００ｉ）を用いて銅量の分析を行った。 (Measurement of copper content in silver particle powder)
Since the analysis error may occur when the silver component remains, the following pretreatment was performed to remove the silver component. 10 g of silver particle powder is put into a 300 ml conical beaker, and then 15 ml of nitric acid solution is added to dissolve the silver particle powder. The dissolved solution is heated on a hot plate set at 250 ° C. and concentrated to the extent that it does not evaporate to dryness. After the concentrated solution is allowed to cool, pure water is added. Make sure there is no cloudiness or suspended matter in the solution. If there is cloudiness or suspended matter in the solution, repeat the steps of adding nitric acid, concentrating with heat, and allowing it to cool until it disappears. Hydrochloric acid is added to a solution that is free from cloudiness and suspended matter to produce silver chloride. Thereafter, the mixture was separated into solid and liquid by filtration to separate the silver chloride and the filtrate, and the filtrate was analyzed for the amount of copper using ICP-MS (AGILENT 7500i manufactured by Agilent Technologies).
　（ＢＥＴ法による比表面積測定）
　銀粒子粉末０．２ｇを２５℃、４５ｃｃ／ｍｉｎのＮ2雰囲気下で２０分間前処理を行った後、ユアサアイオニクス製の４Ｓ－Ｕ２若しくはこの製品の同等品を用いて行った。 (Specific surface area measurement by BET method)
After 0.2 g of silver particle powder was pretreated for 20 minutes in an N 2 atmosphere at 25 ° C. and 45 cc / min, 4S-U2 manufactured by Yuasa Ionics or an equivalent of this product was used.
　（ＴＡＰ密度測定）
　特開２００７－２６３８６０号に記載されている測定法を用いて行った。 (TAP density measurement)
The measurement was performed using the measurement method described in JP-A-2007-263860.
　（銀膜の体積抵抗値）
　銀粒子粉末をペースト化し、ガラス基板に塗膜した。塗膜したガラス基板を乾燥機（ヤマト科学株式会社製）にて各々実施例、比較例中に示す温度と時間で焼成した。焼成した膜の厚さ１μｍ当りの体積抵抗値を抵抗率計（三菱化学アナリテック株式会社製ロレスタＧＰ）を用いて測定し、膜の厚さは表面粗度計（株式会社東京精密製サーフコム１５００Ｄ）を用いて測定をすることで膜の体積抵抗値を算出した。 (Volume resistance value of silver film)
The silver particle powder was pasted and coated on a glass substrate. The coated glass substrate was baked with a dryer (manufactured by Yamato Scientific Co., Ltd.) at the temperatures and times shown in the examples and comparative examples. The volume resistance value per 1 μm thickness of the fired film was measured using a resistivity meter (Loresta GP manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the film thickness was measured by a surface roughness meter (Surfcom 1500D manufactured by Tokyo Seimitsu Co., Ltd.). ) Was used to calculate the volume resistance value of the film.
以下実施例について詳細に説明する。 Examples will be described in detail below.
　（実施例１）
　実施例１～７には反応槽に５Ｌ反応槽を使用した。また、攪拌のために羽根のついた攪拌棒を反応槽中心に設置した。反応槽には温度をモニターするための温度計を設置し、また溶液に下部より窒素を供給できるようにノズルを配設した。 Example 1
In Examples 1 to 7, a 5 L reaction vessel was used as the reaction vessel. In addition, a stirring bar with a blade was installed at the center of the reaction tank for stirring. A thermometer for monitoring the temperature was installed in the reaction tank, and a nozzle was provided so that nitrogen could be supplied to the solution from the bottom.
　まず、反応槽に水を３４００ｇ入れ、残存酸素を除くため反応槽下部から窒素を３０００ｍＬ／分の流量で６００秒間流した。その後、反応槽上部から３０００ｍＬ／分の流量で供給し、反応槽中を窒素雰囲気とした。そして、反応槽内の溶液温度が６０℃になるように攪拌しながら温度調整を行った。そして、アンモニアとして２８質量％含有するアンモニア水７ｇを反応槽に投入した後、液を均一にするために１分間攪拌した。 First, 3400 g of water was put into the reaction tank, and nitrogen was passed from the lower part of the reaction tank at a flow rate of 3000 mL / min for 600 seconds in order to remove residual oxygen. Then, it supplied at the flow volume of 3000 mL / min from the reaction tank upper part, and made the nitrogen atmosphere in the reaction tank. And temperature adjustment was performed, stirring so that the solution temperature in a reaction tank might be 60 degreeC. Then, 7 g of ammonia water containing 28% by mass as ammonia was added to the reaction vessel, and then stirred for 1 minute in order to make the solution uniform.
　次に保護剤としてヘキサン酸（和光純薬工業株式会社製）４５．５ｇ（銀に対してモル比で１．９８にあたる）を添加し、保護剤を溶解するため４分間攪拌した。その後、還元剤として５０質量％のヒドラジン水和物（大塚化学株式会社製）水溶液を２３．９ｇ（銀に対して４．８２当量にあたる）添加し、これを還元剤溶液とした。 Next, 45.5 g of hexanoic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a protective agent (corresponding to a molar ratio of 1.98 with respect to silver) was added and stirred for 4 minutes to dissolve the protective agent. Thereafter, 23.9 g (corresponding to 4.82 equivalents of silver) of a 50% by mass hydrazine hydrate (manufactured by Otsuka Chemical Co., Ltd.) aqueous solution as a reducing agent was added to obtain a reducing agent solution.
　別の容器に硝酸銀結晶（和光純薬工業株式会社製）３３．８ｇを水１８０ｇに溶解した硝酸銀水溶液を用意し、これを銀塩水溶液とした。この銀塩水溶液中に更に硝酸銅三水和物（和光純薬工業株式会社製）を銅換算で銀に対して１ｐｐｍ相当量添加した。なお、ここでの硝酸銅三水和物の添加は、予め既知濃度の硝酸銅三水和物水溶液を作製し、それを希釈したものを添加することで調整を行っている。また、銀塩水溶液は反応槽内の還元剤溶液と同じ６０℃に温度調整を行った。 In another container, an aqueous silver nitrate solution prepared by dissolving 33.8 g of silver nitrate crystals (manufactured by Wako Pure Chemical Industries, Ltd.) in 180 g of water was prepared, and this was used as an aqueous silver salt solution. To this silver salt aqueous solution, copper nitrate trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added in an amount equivalent to 1 ppm with respect to silver in terms of copper. The addition of copper nitrate trihydrate here is adjusted by preparing a copper nitrate trihydrate aqueous solution having a known concentration in advance and adding a diluted solution thereof. Further, the temperature of the silver salt aqueous solution was adjusted to 60 ° C., the same as the reducing agent solution in the reaction vessel.
　その後、銀塩水溶液を還元剤溶液に一挙添加により混合し、還元反応を開始させた。この際、スラリーの色は添加終了から直ちに変化した。攪拌は連続して行い、その状態のまま１０分間熟成させた。その後、攪拌を止め、吸引濾過による固液分離を行い、洗浄廃液の電気伝導率が２．０μＳ／ｃｍ未満となるまで純水による洗浄を行った後、４０℃で１２時間乾燥させることにより、微小銀粒子粉末を得た。なお、得られる粉末は熱に対する感応性が高いため、この温度以上での乾燥は塊状銀になる可能性がある。 Thereafter, an aqueous silver salt solution was added to the reducing agent solution by mixing at once and a reduction reaction was started. At this time, the color of the slurry immediately changed from the end of the addition. Stirring was performed continuously and aged for 10 minutes in that state. Then, stirring is stopped, solid-liquid separation is performed by suction filtration, and after washing with pure water until the electrical conductivity of the washing waste liquid is less than 2.0 μS / cm, by drying at 40 ° C. for 12 hours, A fine silver particle powder was obtained. In addition, since the powder obtained has high sensitivity to heat, drying at a temperature higher than this temperature may result in massive silver.
　（実施例２）
　銀塩水溶液中に添加する硝酸銅三水和物水溶液を、銅換算で銀に対して５ｐｐｍとなる量に変更した以外は実施例１を繰り返した。 (Example 2)
Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 5 ppm based on silver in terms of copper.
　（実施例３）
　銀塩水溶液中に添加する硝酸銅三水和物水溶液を、銅換算で銀に対して１０ｐｐｍとなる量に変更した以外は実施例１を繰り返した。 (Example 3)
Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 10 ppm with respect to silver in terms of copper.
　（銀粒子含有分散液の作製）
　作製した銀粒子粉末６ｇとターピネオール４ｇを混合した。その後、ディスパーを用いて１４００ｒｐｍで９０秒間処理し、三本ロールで１０パスさせて銀粒子含有分散液を作製した。 (Preparation of silver particle-containing dispersion)
6 g of the produced silver particle powder and 4 g of terpineol were mixed. Then, it processed at 1400 rpm for 90 second using a disper, and it was made to pass 10 passes with a three roll, and produced the silver particle containing dispersion liquid.
　（銀塗布膜の作製及び焼成）
　作製した銀粒子含有分散液を、スライドガラス上にアプリケーターを用いて塗膜した。その後、乾燥機（ヤマト科学株式会社製）を用いて１５０℃で３０分間焼成した。また、２００℃で３０分間焼成したサンプルも作製し、それぞれの体積抵抗値を測定した。 (Preparation and baking of silver coating film)
The prepared silver particle-containing dispersion was coated on a slide glass using an applicator. Then, it baked for 30 minutes at 150 degreeC using the dryer (made by Yamato Scientific Co., Ltd.). Moreover, the sample baked for 30 minutes at 200 degreeC was also produced, and each volume resistance value was measured.
　（実施例４）
　銀塩水溶液中に添加する銅源を、亜酸化銅に変更した以外は実施例３の銀粒子の作製工程を繰り返した。 Example 4
The silver particle production process of Example 3 was repeated except that the copper source added to the aqueous silver salt solution was changed to cuprous oxide.
　（実施例５）
　銀塩水溶液中に添加する硝酸銅三水和物水溶液を、銅換算で銀に対して１００ｐｐｍとなる量に変更した以外は実施例１を繰り返した。 (Example 5)
Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 100 ppm with respect to silver in terms of copper.
　（実施例６）
　銀塩水溶液中に添加する銅源を、銅粉に変更した以外は実施例５を繰り返した。 (Example 6)
Example 5 was repeated except that the copper source added to the aqueous silver salt solution was changed to copper powder.
　（実施例７）
　銀塩水溶液中に添加する硝酸銅三水和物水溶液を、銅換算で銀に対して１０００ｐｐｍとなる量に変更した以外は実施例１を繰り返した。 (Example 7)
Example 1 was repeated except that the copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 1000 ppm with respect to silver in terms of copper.
　（実施例８）
　実施例８～１３では反応槽に２００Ｌ反応槽を用いた。５Ｌ反応槽同様に攪拌棒、温度計、窒素ノズルを設置した。まず、反応槽に水を１３７ｋｇ入れ、残存している酸素を抜くため下部より窒素を２０Ｌ／分で６００秒間流した。その後、反応槽上部より２０Ｌ／分で窒素を供給して反応槽内部を窒素雰囲気にした。そして、反応槽内の溶液温度が６０℃になるように攪拌しながら温度を調節した。そして、アンモニアとして２８質量％含有するアンモニア水２８２．３ｇを反応槽に投入した後、液を均一にするために１分間攪拌した。 (Example 8)
In Examples 8 to 13, a 200 L reaction vessel was used as the reaction vessel. A stir bar, a thermometer, and a nitrogen nozzle were installed in the same manner as the 5 L reaction tank. First, 137 kg of water was put into the reaction tank, and nitrogen was passed from the lower part at a rate of 20 L / min for 600 seconds in order to remove the remaining oxygen. Thereafter, nitrogen was supplied from the upper part of the reaction tank at a rate of 20 L / min to make the inside of the reaction tank a nitrogen atmosphere. And temperature was adjusted, stirring so that the solution temperature in a reaction tank might be 60 degreeC. Then, 282.3 g of ammonia water containing 28% by mass as ammonia was added to the reaction vessel, and then stirred for 1 minute to make the solution uniform.
　次に保護剤としてヘキサン酸（和光純薬工業株式会社製）１８１８．８ｇ（銀に対してモル比で１．９８にあたる）を添加し、保護剤を溶解するため４分間攪拌した。その後、還元剤として８０質量％のヒドラジン水和物（大塚化学株式会社製）水溶液を５９６．３ｇ（銀に対して４．８２当量にあたる）添加し、これを還元剤溶液とした。 Next, 1818.8 g of hexanoic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a protective agent (corresponding to a molar ratio of 1.98 with respect to silver) was added and stirred for 4 minutes to dissolve the protective agent. Then, 596.3 g (corresponding to 4.82 equivalents of silver) of an 80% by mass hydrazine hydrate (manufactured by Otsuka Chemical Co., Ltd.) aqueous solution as a reducing agent was added, and this was used as a reducing agent solution.
　別の容器に硝酸銀結晶（和光純薬工業株式会社製）１３５０．３ｇを水７２００ｇに溶解した硝酸銀水溶液を用意し、これを銀塩水溶液とした。この銀塩水溶液中に更に硝酸銅三水和物（和光純薬工業株式会社製）０．０３２５ｇ（銅換算で銀に対して１０ｐｐｍにあたる）を添加した。なお、銀塩水溶液は反応槽内の還元剤溶液と同じ６０℃に温度調整を行った。 In a separate container, an aqueous silver nitrate solution in which 1350.3 g of silver nitrate crystals (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 7200 g of water was prepared, and this was used as an aqueous silver salt solution. To this silver salt aqueous solution, 0.0325 g of copper nitrate trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) (corresponding to 10 ppm of silver in terms of copper) was added. The temperature of the silver salt aqueous solution was adjusted to 60 ° C., the same as the reducing agent solution in the reaction vessel.
　その後、銀塩水溶液を還元剤溶液に一挙添加することにより混合し、還元反応を開始させた。攪拌は連続して行い、その状態のまま１０分間熟成させた。その後、攪拌を止め、フィルタープレスによる固液分離、洗浄液の電気伝導率が２．０μＳ／ｃｍ未満となるまで純水による洗浄を行った後、及び４０℃１２時間以上の乾燥を経て、微小銀粒子粉末を得た。 Thereafter, the silver salt aqueous solution was added to the reducing agent solution at once and mixed to start the reduction reaction. Stirring was performed continuously and aged for 10 minutes in that state. Thereafter, stirring is stopped, solid-liquid separation by a filter press, washing with pure water until the electric conductivity of the washing liquid becomes less than 2.0 μS / cm, and after drying at 40 ° C. for 12 hours or more, fine silver Particle powder was obtained.
　（分散液の作成）
　得られた微小銀粒子粉末を溶媒等へ添加して分散液を作成した。微小銀粒子粉末１．０ｇ、ブチルカルビトールアセテート（和光純薬工業株式会社製）１０．０ｇ、分散剤としてＤｉｓｐｅｒＢＹＫ２０２０（ビックケミー・ジャパン社製）０．１ｇをそれぞれ秤量した。それらを試験管中で混合し、超音波分散機で１０分間分散させた。その結果、均一に分散して試験管底にも沈殿物は見られなかった。また、２４時間静置した後にも試験管底に沈殿物は見られず、再分散性が良好であった。 (Creation of dispersion)
The obtained fine silver particle powder was added to a solvent or the like to prepare a dispersion. 1.0 g of fine silver particle powder, 10.0 g of butyl carbitol acetate (manufactured by Wako Pure Chemical Industries, Ltd.), and 0.1 g of DisperBYK2020 (manufactured by Big Chemie Japan) as a dispersant were weighed. They were mixed in a test tube and dispersed with an ultrasonic disperser for 10 minutes. As a result, it was uniformly dispersed and no precipitate was observed on the bottom of the test tube. In addition, no precipitate was seen on the bottom of the test tube after standing for 24 hours, and the redispersibility was good.
　（実施例９）
　銀塩水溶液中に添加する硝酸銅三水和物量を、銅換算で銀に対して２０ｐｐｍとなる量に変更した以外は実施例８を繰り返した。 Example 9
Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 20 ppm based on silver in terms of copper.
　（実施例１０）
　銀塩水溶液中に添加する硝酸銅三水和物量を、銅換算で銀に対して５０ｐｐｍとなる量に変更した以外は実施例８を繰り返した。 (Example 10)
Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 50 ppm based on silver in terms of copper.
　（実施例１１）
　銀塩水溶液中に添加する硝酸銅三水和物量を、銅換算で銀に対して１００ｐｐｍとなる量に変更した以外は実施例８を繰り返した。 Example 11
Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 100 ppm based on silver in terms of copper.
　（実施例１２）
　銀塩水溶液中に添加する硝酸銅三水和物量を、銅換算で銀に対して３００ｐｐｍとなる量に変更した以外は実施例８を繰り返した。 (Example 12)
Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 300 ppm based on silver in terms of copper.
　（実施例１３）
　銀塩水溶液中に添加する硝酸銅三水和物量を、銅換算で銀に対して５００ｐｐｍとなる量に変更した以外は実施例８を繰り返した。 (Example 13)
Example 8 was repeated except that the amount of copper nitrate trihydrate added to the aqueous silver salt solution was changed to an amount of 500 ppm based on silver in terms of copper.
　（比較例１）
　銀塩水溶液中に硝酸銅三水和物を添加しなかったこと以外は実施例１を繰り返した。反応スラリーの色は添加終了から約３０秒で変化が終了していた。 (Comparative Example 1)
Example 1 was repeated except that copper nitrate trihydrate was not added to the aqueous silver salt solution. The change of the color of the reaction slurry was completed about 30 seconds after the addition was completed.
　（比較例２）
　銀塩水溶液中に硝酸銅三水和物を添加しなかったこと以外は実施例８を繰り返した。 (Comparative Example 2)
Example 8 was repeated except that copper nitrate trihydrate was not added to the aqueous silver salt solution.
　（比較例３）
　銀塩水溶液中に添加する硝酸銅三水和物水溶液量を、銅換算で銀に対して６０００ｐｐｍとなる量に変更した以外は実施例１を繰り返した。 (Comparative Example 3)
Example 1 was repeated except that the amount of copper nitrate trihydrate aqueous solution added to the silver salt aqueous solution was changed to an amount of 6000 ppm based on silver in terms of copper.
　（比較例４）
　銀塩水溶液中に添加する硝酸銅三水和物水溶液量を、銅換算で銀に対して６００００ｐｐｍとなる量に変更した以外は実施例１を繰り返した。 (Comparative Example 4)
Example 1 was repeated except that the amount of copper nitrate trihydrate aqueous solution added to the aqueous silver salt solution was changed to an amount of 60000 ppm based on silver in terms of copper.
　（比較例５）
　硝酸銅三水和物の代わりに硝酸ニッケル六水和物水溶液（和光純薬工業株式会社製）をニッケル換算で１００ｐｐｍとなる量を添加することに変更した以外は実施例１を繰り返した。 (Comparative Example 5)
Example 1 was repeated except that nickel nitrate hexahydrate aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of copper nitrate trihydrate to add an amount of 100 ppm in terms of nickel.
　（比較例６）
　硝酸銅三水和物の代わりに硝酸鉄（ＩＩＩ）九水和物水溶液（和光純薬工業株式会社製）を鉄換算で１００ｐｐｍとなる量を添加することに変更した以外は実施例１を繰り返した。 (Comparative Example 6)
Example 1 was repeated except that an iron (III) nitrate nonahydrate aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of copper nitrate trihydrate to add an amount of 100 ppm in terms of iron. It was.
　（比較例７）
　比較例１の還元反応終了後に反応スラリーに対して、硝酸銅三水和物水溶液を銅換算で銀に対して３０００ｐｐｍとなる量添加し、そのまま５分間攪拌を続けた。その後、攪拌を止めて濾過・洗浄を行った。 (Comparative Example 7)
After completion of the reduction reaction of Comparative Example 1, an aqueous solution of copper nitrate trihydrate was added to the reaction slurry in an amount of 3000 ppm with respect to silver in terms of copper, and stirring was continued for 5 minutes. Thereafter, stirring was stopped and filtration and washing were performed.
　（比較例８）
　還元剤のヒドラジン水和物量を銀に対して９．６当量となる量に変更した以外は、比較例１を繰り返した。還元反応開始後直ちに反応スラリーの色変化が終了し、反応が完結していることが確認された。 (Comparative Example 8)
Comparative Example 1 was repeated except that the amount of hydrazine hydrate of the reducing agent was changed to an amount that was 9.6 equivalents with respect to silver. Immediately after the start of the reduction reaction, the color change of the reaction slurry was completed, and it was confirmed that the reaction was complete.
　実施例及び比較例の反応スケール、製造時に添加した添加物及びその添加量、反応後の銀粒子粉末の中に含有されるＣｕ含有量、乾燥状態の銀粒子粉末のＢＥＴ比表面積、ＴＡＰ密度、ＴＥＭ径及び変動係数、銀膜の体積抵抗値を表１に示した。また、図１～３に実施例１、３及び５のＴＥＭ像を、図４に比較例１のＴＥＭ像を示した。ＴＥＭ写真の倍率は全て１７４，０００倍である。なお、図１～９の写真の右下の矢印はすべて１００ｎｍをあらわす。 Reaction scales of Examples and Comparative Examples, additives added at the time of production and their addition amount, Cu content contained in the silver particle powder after the reaction, BET specific surface area of the dried silver particle powder, TAP density, Table 1 shows the TEM diameter, the coefficient of variation, and the volume resistance value of the silver film. 1 to 3 show TEM images of Examples 1, 3 and 5, and FIG. 4 shows a TEM image of Comparative Example 1. The magnification of all TEM photographs is 174,000 times. Note that the arrows on the lower right of the photographs in FIGS. 1 to 9 all represent 100 nm.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　また、図５、６には実施例８及び１１のＴＥＭ像を、図７、８には比較例６、７のＴＥＭ像を示し、図９には比較例８のＴＥＭ像を示した。また、図１０には実施例及び比較例に関して、Ｃｕ添加量とＢＥＴの関係を表すグラフを５Ｌ反応時と２００Ｌ反応時に分けて示した。 5 and 6 show TEM images of Examples 8 and 11, FIGS. 7 and 8 show TEM images of Comparative Examples 6 and 7, and FIG. 9 shows a TEM image of Comparative Example 8. FIG. 10 is a graph showing the relationship between the amount of added Cu and BET for the examples and comparative examples separately for the 5L reaction and the 200L reaction.
　まず、表１の実施例１～７、比較例１及び図１０を参照する。図１０は縦軸がＢＥＴ、横軸がＡｇに対するＣｕの添加量をとったものである。白丸と白三角はそれぞれ５Ｌと２００Ｌの反応槽で作製した実施例の結果を表わす。なお、黒丸印と黒三角印は、それぞれ５Ｌと２００Ｌの反応槽で比較例である。具体的には黒丸印が比較例１で黒三角印は比較例２である。 First, referring to Examples 1 to 7, Comparative Example 1 and FIG. 10 in Table 1. In FIG. 10, the vertical axis represents BET and the horizontal axis represents the amount of Cu added to Ag. White circles and white triangles represent the results of Examples prepared in 5 L and 200 L reaction vessels, respectively. The black circles and black triangles are comparative examples in 5 L and 200 L reaction tanks, respectively. Specifically, the black circle mark is Comparative Example 1 and the black triangle mark is Comparative Example 2.
　Ｃｕが添加されていない比較例に対して、Ｃｕが１ｐｐｍ添加された実施例１でさえ、ＢＥＴは７ｍ2／ｇ以上高かった。すなわち、実施例に対して比較例Ｃｕを添加して反応した際に銀粒子粉末のＢＥＴが増加していることが分かる。また、銅粉末（実施例６）、亜酸化銅（実施例４）の添加によっても同様の効果が得られていたため、添加する銅成分の形態に関わらず本発明の効果が得られることが分かる。また、その効果はＣｕの１ｐｐｍ添加から顕著に現れ、１０ｐｐｍ付近で飽和していた。 Even in Example 1 in which 1 ppm of Cu was added, the BET was 7 m 2 / g or more higher than the comparative example in which Cu was not added. In other words, it can be seen that the BET of the silver particle powder is increased when the comparative example Cu is added to the example and reacted. Moreover, since the same effect was acquired also by addition of copper powder (Example 6) and cuprous oxide (Example 4), it turns out that the effect of this invention is acquired irrespective of the form of the copper component to add. . Moreover, the effect appeared notably from the addition of 1 ppm of Cu, and was saturated around 10 ppm.
　これより極微量の銅添加がＢＥＴの増大に対して非常に顕著な効果が現れていることが分かる。また、図４の比較例１のＴＥＭ像を見ると、小さな粒子と粗大粒子とが混在している他、凝結状の粒子が多数存在していた。一方、図１で示した実施例１の写真では一次粒子が明確に識別でき粗大粒子は見当たらなかった。このことから、銅を添加した場合には凝結した粒子が減少し、粒度が揃う効果が得られることが分かる。 From this, it can be seen that the addition of a very small amount of copper has a very remarkable effect on the increase in BET. Moreover, when the TEM image of the comparative example 1 of FIG. 4 is seen, in addition to a mixture of small particles and coarse particles, there are many condensed particles. On the other hand, in the photograph of Example 1 shown in FIG. 1, primary particles could be clearly identified, and no coarse particles were found. From this, it can be seen that when copper is added, the aggregated particles are reduced and the effect of uniform particle size is obtained.
　このことは、ＴＥＭ像から得られる変動係数によっても、示されている。すなわち、実施例１～７の変動係数は１７～２１％と小さい値となっており、非常に粒度分布の狭いことを示したが、図４を見ると明らかに粒度分布が広くなっている。また、図１～３を見ると銅を添加した場合には全て銀粒子がそれぞれ孤立して存在しており、非常に分散性に優れ且つ粒子径バラつきが小さいものができていた。 This is also indicated by the coefficient of variation obtained from the TEM image. That is, the variation coefficients of Examples 1 to 7 are as small as 17 to 21%, indicating that the particle size distribution is very narrow. However, when FIG. 4 is viewed, the particle size distribution is clearly wide. As can be seen from FIGS. 1 to 3, when copper is added, silver particles are present in isolation from each other, and have excellent dispersibility and small variation in particle diameter.
　次に実施例８～１３、比較例２及び図５、６を参照する。５Ｌ反応同様、銅成分の添加によって銀粒子粉末のＢＥＴが増加していた。また、２００Ｌ反応においても粒子径の整った銀粒子が作製できていた。これより、本発明にかかる製造方法は反応スケールに関わらず粒子径バラつきを改善することができることが分かった。 Next, refer to Examples 8 to 13, Comparative Example 2, and FIGS. Similar to the 5 L reaction, the addition of the copper component increased the BET of the silver particle powder. In addition, silver particles having a uniform particle size were prepared even in the 200 L reaction. From this, it was found that the production method according to the present invention can improve the particle size variation regardless of the reaction scale.
　また、図１０から２００Ｌ反応の場合、銅成分添加量とＢＥＴの関係が５Ｌ反応時よりも緩い傾きとなっていることが分かる。これは、製造上の観点から見ると非常に好ましいことである。すなわち、前述のように銅成分添加量の制御によって所望のＢＥＴを有する銀粒子粉末を作製しようとした場合、２００Ｌ反応ではこの銅成分添加量の制御幅が広くなっているため、簡便に所望の銀粒子を得ることが可能であると考えられる。 Further, it can be seen from FIG. 10 that in the case of 200 L reaction, the relationship between the amount of copper component added and BET has a gentler slope than that in the case of 5 L reaction. This is very preferable from a manufacturing point of view. That is, as described above, when the silver particle powder having a desired BET is prepared by controlling the amount of copper component added, the control range of the amount of copper component added is widened in the 200L reaction. It is considered possible to obtain silver particles.
　次に比較例３、４を参照する。比較例３、４は銅成分をそれぞれ６０００ｐｐｍ（０．６質量％）、６００００ｐｐｍ（６質量％）添加したものであるが、このようにして得られる銀粒子では銀粒子中に含まれる銅量も非常に多くなっている。比較例３、４の銀粒子を銀膜にした場合、抵抗値が悪化しているのはこのことに起因していると考えられる。 Next, refer to Comparative Examples 3 and 4. Comparative Examples 3 and 4 were obtained by adding 6000 ppm (0.6% by mass) and 60000 ppm (6% by mass), respectively, of the copper component. In the silver particles thus obtained, the amount of copper contained in the silver particles was It has become very much. When the silver particles of Comparative Examples 3 and 4 are made into a silver film, it is considered that this is because the resistance value is deteriorated.
　また、比較例５、６及び図７、８を参照する。比較例５、６はそれぞれ銅成分の代わりにニッケル成分、鉄成分を添加したものだが、本発明のような効果が得られていない。本発明にかかる製造方法においては、銅成分を添加することが必要であることが分かる。 Reference is also made to Comparative Examples 5 and 6 and FIGS. In Comparative Examples 5 and 6, a nickel component and an iron component were added instead of the copper component, respectively, but the effect as in the present invention was not obtained. It turns out that it is necessary to add a copper component in the manufacturing method concerning this invention.
　また、比較例７を参照する。比較例７は還元反応終了後に銅成分を添加したものであるが、本発明のような効果が得られなかった。本発明にかかる製造方法においては、銅成分を還元反応終了前に添加することが必要であることが分かる。 Reference is also made to Comparative Example 7. In Comparative Example 7, a copper component was added after completion of the reduction reaction, but the effect as in the present invention was not obtained. In the manufacturing method concerning this invention, it turns out that it is necessary to add a copper component before completion | finish of a reductive reaction.
　また、比較例８と図９を見ると、還元剤量を増加させることで還元反応は早くなったものの図から粗大粒子が多数発生していることが分かる。これより、単純に還元反応を早くすれば良いわけではなく、銅成分の存在が粒度分布や分散性にとって必要であることが分かる。 Further, when Comparative Example 8 and FIG. 9 are seen, it can be seen that a large number of coarse particles are generated, although the reduction reaction is accelerated by increasing the amount of the reducing agent. From this, it can be seen that the reduction reaction is not simply accelerated, and the presence of the copper component is necessary for the particle size distribution and dispersibility.
　また、本実施例では、銅成分を銀成分と予め混合しておき、還元剤液と混ぜた。従って、還元反応が開始される時点から銅成分が混合液中に存在していたので、還元反応の終了点を反応スラリーの色変化で判断した。しかし、反応スラリーの色変化が終了しても、還元反応自体はまだ終了してはいない場合もある。従って、銀化合物溶液と保護剤と還元剤溶液だけで還元反応を行い、反応スラリーの色変化が終了した場合でも、銅成分を添加することで本発明の効果を得ることはできる。 In this example, the copper component was previously mixed with the silver component and then mixed with the reducing agent solution. Therefore, since the copper component was present in the mixed solution from the time when the reduction reaction was started, the end point of the reduction reaction was judged from the color change of the reaction slurry. However, even if the color change of the reaction slurry is completed, the reduction reaction itself may not be completed yet. Therefore, even when the reduction reaction is performed only with the silver compound solution, the protective agent, and the reducing agent solution, and the color change of the reaction slurry is completed, the effect of the present invention can be obtained by adding the copper component.
　本発明の製造方法は大スケールの反応でも小スケール同様の銀粒子を容易に作製することができるため、量産性に優れている。また、本発明にかかる銀粒子は、粒子径のバラつきが小さく、また各種溶媒に再分散させることができるため、金属配線用途に用いる分散液にとって好適なものである。
  Since the production method of the present invention can easily produce silver particles similar to the small scale even in a large scale reaction, it is excellent in mass productivity. Further, the silver particles according to the present invention have a small variation in particle diameter and can be redispersed in various solvents, and therefore are suitable for dispersions used for metal wiring applications.

Claims (15)

  1. 銅の存在下で銀化合物と保護剤と還元剤とを混合し反応させる銀粒子の製造方法。 A method for producing silver particles in which a silver compound, a protective agent, and a reducing agent are mixed and reacted in the presence of copper.
  2. 銀化合物溶液と液状保護剤とを混合する工程、混合液に銅化合物を加えて反応液中に銅を存在させる工程、その後液状還元剤を添加して液中の銀イオンを還元する工程を各々備える、銀粒子の製造方法。 A step of mixing a silver compound solution and a liquid protective agent, a step of adding a copper compound to the mixed solution to cause copper to exist in the reaction solution, and a step of adding a liquid reducing agent to reduce silver ions in the solution. A method for producing silver particles.
  3. 液状保護剤と液状還元剤を混合し保護剤と還元剤の混合溶液を得る工程と、
    銀化合物溶液と銅化合物溶液を混合し銀化合物と銅化合物の混合溶液を得る工程と、
    前記保護剤と還元剤の混合溶液に前記銀化合物と銅化合物の混合溶液を添加し還元反応させる銀粒子の製造方法。     Mixing a liquid protective agent and a liquid reducing agent to obtain a mixed solution of the protective agent and the reducing agent;
    Mixing a silver compound solution and a copper compound solution to obtain a mixed solution of a silver compound and a copper compound;
    A method for producing silver particles, wherein a mixed solution of the silver compound and a copper compound is added to a mixed solution of the protective agent and a reducing agent to cause a reduction reaction.
  4. 前記銅成分の合計添加量が、銅換算で前記反応液中の銀に対して１～２０００ｐｐｍの量である請求項１乃至３のいずれか一の請求項に記載された銀粒子の製造方法。 The method for producing silver particles according to any one of claims 1 to 3, wherein the total addition amount of the copper component is 1 to 2000 ppm in terms of copper with respect to silver in the reaction solution.
  5. 前記還元反応は４０～８０℃で行う、請求項１～４のいずれか一の請求項に記載された銀粒子の製造方法。 The method for producing silver particles according to any one of claims 1 to 4, wherein the reduction reaction is carried out at 40 to 80 ° C.
  6. 前記保護剤は炭素、窒素、酸素のいずれか一種以上を含む、請求項１～５のいずれか一の請求項に記載された銀粒子の製造方法。 The method for producing silver particles according to any one of claims 1 to 5, wherein the protective agent contains at least one of carbon, nitrogen, and oxygen.
  7. 前記保護剤の沸点は２５０℃以下である、請求項１～６のいずれか一の請求項に記載された銀粒子の製造方法。 The method for producing silver particles according to any one of claims 1 to 6, wherein the protective agent has a boiling point of 250 ° C or lower.
  8. 前記保護剤が持つ官能基が、カルボキシル基及びアミノ基のいずれか、もしくはその両方を有している、請求項１～７のいずれか一の請求項に記載された銀粒子の製造方法。 The method for producing silver particles according to any one of claims 1 to 7, wherein the functional group possessed by the protective agent has one or both of a carboxyl group and an amino group.
  9. １～１０００ｐｐｍの銅を含み、ＴＥＭ像から計測される粒子径の算術平均値が１～１００ｎｍであり、ＢＥＴ法で測定した比表面積が５～４０ｍ２／ｇである、銀粒子。 Silver particles containing 1 to 1000 ppm of copper, having an arithmetic average particle diameter measured from a TEM image of 1 to 100 nm, and a specific surface area measured by the BET method of 5 to 40 m 2 / g.
  10. 前記粒子径計測値の変動係数が３０％未満である請求項９に記載の銀粒子。 The silver particle according to claim 9, wherein a coefficient of variation of the particle diameter measurement value is less than 30%.
  11. 前記銀粒子表面に炭素、窒素、酸素のいずれか一種以上を含む保護剤が存在する、請求項９又は１０に記載の銀粒子。 The silver particle according to claim 9 or 10, wherein a protective agent containing any one or more of carbon, nitrogen, and oxygen is present on the surface of the silver particle.
  12. 前記保護剤は有機カルボン酸もしくはその誘導体からなり、炭素数が３～８である、請求項９ないし１１のいずれか一の請求項に記載された銀粒子。 The silver particle according to any one of claims 9 to 11, wherein the protective agent comprises an organic carboxylic acid or a derivative thereof and has 3 to 8 carbon atoms.
  13. 前記保護剤の沸点が２５０℃以下である請求項８～１２のいずれか一の請求項に記載された銀粒子。 The silver particles according to any one of claims 8 to 12, wherein the protective agent has a boiling point of 250 ° C or lower.
  14. 前記官能基は、カルボキシル基又はアミノ基からなる群より選ばれる１種以上の官能基である請求項８～１３のいずれか一の請求項に記載された銀粒子。 The silver particle according to any one of claims 8 to 13, wherein the functional group is one or more functional groups selected from the group consisting of a carboxyl group or an amino group.
  15. 請求項８～１４のいずれか一の請求項に記載された銀粒子を含む分散液。
     
     
     
     
          A dispersion containing the silver particles according to any one of claims 8 to 14.




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