WO2019035246A1 - Method for producing silver nanoparticles having wide particle size distribution, and silver nanoparticles - Google Patents

Method for producing silver nanoparticles having wide particle size distribution, and silver nanoparticles Download PDF

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WO2019035246A1
WO2019035246A1 PCT/JP2018/015456 JP2018015456W WO2019035246A1 WO 2019035246 A1 WO2019035246 A1 WO 2019035246A1 JP 2018015456 W JP2018015456 W JP 2018015456W WO 2019035246 A1 WO2019035246 A1 WO 2019035246A1
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silver
silver nanoparticles
particles
compound
particle size
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PCT/JP2018/015456
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French (fr)
Japanese (ja)
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亮 中浜
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御国色素株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • 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
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/30—Making metallic powder or suspensions thereof using chemical processes with decomposition of metal compounds, e.g. by pyrolysis
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables

Definitions

  • the present invention relates to a method for producing silver particles having a broad particle size distribution and in which a specific amino alcohol having an ether bond is bound as a protective agent, and silver nanoparticles.
  • Silver nanoparticles are used as electrical wiring on a substrate or as a bonding material for power device semiconductors because they sinter at low temperature due to the melting point lowering property of metal nanoparticles.
  • silver nanoparticles are easily aggregated due to their fineness, and they are easily fused due to the decrease in melting point, so an organic layer called a protective agent is present on the surface of silver nanoparticles.
  • fatty acids, alkylamines and the like are often used, but particularly silver nanoparticles coated with alkylamines or alkyldiamines release protective agents at relatively low temperatures, and silver nanoparticles that can be baked at low temperatures (Patent Documents 1 and 2).
  • Patent Document 3 uses silver nanoparticles having a primary particle diameter of about several nm to several tens of nm, and provides conductivity of 5 to 20 ⁇ m. Silver coating compositions (inks) from which silver coatings can be obtained have been reported.
  • Patent Document 4 by containing silver particles with a particle diameter of 100 to 200 nm by 30% or more based on the number of particles, resistance can be reduced when forming a sintered body, and water can be reduced to 5 to 100 parts by weight of silver compound. It is described that such silver particles can be obtained by being contained in a 100 parts by weight reaction system.
  • silver nanoparticles are formed using a complex formation reaction of a silver compound and an amine compound.
  • silver oxalate is complexed with an alkylamine or an alkyldiamine in the absence of a solvent.
  • complex formation in the absence of a solvent results in a solid with no fluidity, which makes it difficult to agitate, lacks uniformity of the system, and locally causes exothermic reaction, resulting in problems in quality and safety, Industrial practical application is difficult.
  • Patent No. 5574761 gazette JP 2012-162767 A Patent No. 6001861 gazette Patent No. 5795096 Patent 5975440 gazette Patent No. 6026565 JP, 2016-132825, A JP, 2015-40319, A JP 2014-152337 A
  • the coating film of the thickness which does not reach 8 micrometers is produced in the Example. Even if a conductive coating film of 10 ⁇ m or more is formed, the silver particles are mainly particles having a primary particle diameter of several tens of nm, so the amount of the organic protective agent is large, and volumetric shrinkage occurs due to the removal of the protective agent. Is low, there is a high possibility of the occurrence of breakage due to cracks.
  • the present invention solves the above problems and provides a method of producing silver nanoparticles in consideration of scale-up in workability, safety, environment, etc., and a method of producing silver nanoparticles having a particle size distribution range of high distribution.
  • the task is to provide.
  • the present inventors diligently studied to solve these problems. As a result, by using a specific amino alcohol having an ether bond as an amine compound capable of forming a complex with a silver compound, the emission of alkylamine is suppressed, and it is environmentally friendly, and at the same time, the silver particles obtained have a particle size It has been found that the obtained sintered coating film also has excellent performance, and reaches the present invention.
  • the present invention includes the following inventions.
  • a thermally formed silver compound (a) and an amine compound (b) capable of forming a complex with (a) are reacted in an organic solvent (c) to form a complex, and the resulting complex is
  • (b) is a linear amino alcohol, and amino groups at both ends of the linear molecule. It is an amino alcohol which has and one hydroxyl group and has an ether bond in a linear molecular structure, and the manufacturing method of the silver nanoparticle characterized by the above-mentioned.
  • a silver nanoparticle is produced by the method according to any one of the above (1) to (8), the obtained silver nanoparticle is dispersed in an organic solvent, and an organic binder is further added.
  • a method of producing a silver coating composition A method of producing a silver coating composition.
  • the silver nanoparticle dispersion obtained by the method described in the above (8) or the silver coating composition obtained by the method described in the above (9) is coated on a substrate and fired to form a silver conductive layer
  • a method of producing a silver conductive material comprising the steps of
  • the silver coating composition containing silver particles with controlled particle size according to the present invention can be sintered even in a low temperature range of 150 ° C. or lower, and the sintered body produced has a low resistance value close to that of bulk silver.
  • the present invention is a material capable of forming a silver wiring having a thickness of several to several tens of ⁇ m on a relatively low heat resistant plastic substrate such as PET or polypropylene by a printing method typified by screen printing, or conductive bonding. It can be expected to be used as a bonding material for electrical devices that handle large currents such as materials and power devices.
  • the amount of amine compound used is smaller than that of the conventional synthesis method, and an amine compound which forms a complex with a thermally decomposable silver compound has a specific carbon number of 4 or less
  • the use of amino alcohol can further reduce the use of alkylamines with high human and environmental loads, thereby providing a highly safe production method in scaled up industrial production.
  • FIG. 1 is an image diagram showing a coordination model of an amine compound to a silver atom and a growth image.
  • FIG. 1-1 is a coordination model (straight chain type) of diglycolamine to a silver atom
  • FIG. 1-2 is a coordination model of diglycolamine to a silver atom (OH group approach type).
  • FIGS. 1-3 are images of coordination models of alkylamines to silver atoms.
  • Fig. 1-4 is an image showing the image of linear adsorption and silver particle growth that is rich in alkylamine
  • Fig. 1-5 is an image showing the image of O atom adsorption type adsorption of amino alcohol and silver particle growth
  • FIG. 1 6 is an image showing a realistic adsorption of amino alcohol and a silver particle growth image.
  • FIG. 2 is a view showing a SEM photograph of particles obtained in Example 1.
  • FIG. 3 is a view showing a SEM photograph of particles obtained in Example 2.
  • FIG. 4 is a view showing a SEM photograph of particles obtained in Example 3.
  • FIG. 5 is a view showing a SEM photograph of particles obtained in Example 4.
  • FIG. 6 is a view showing a SEM photograph of particles obtained in Example 5.
  • FIG. 7 is a view showing a SEM photograph of particles obtained in Example 6.
  • FIG. 8 is a view showing a SEM photograph of the particles obtained in Example 7.
  • FIG. 9 is a view showing a SEM photograph of particles obtained in Example 8.
  • FIG. 10 is a view showing a SEM photograph of particles obtained in Comparative Example 1.
  • FIG. 11 is a view showing STEM photographs of particles obtained in Comparative Examples 2 and 3.
  • FIG. 12 is a view showing a STEM photograph of particles obtained in Comparative Example 4.
  • FIG. 13 is a view showing a SEM photograph of the particles obtained in Comparative Example 5.
  • FIG. 14 is a view showing a SEM photograph of particles obtained in Comparative Example 6.
  • FIG. 15 is a view showing a SEM photograph of particles obtained in Comparative Example 7.
  • FIG. 16 is a view showing a SEM photograph of particles obtained in Comparative Example 8.
  • FIG. 17 is a view showing a SEM photograph of particles obtained in Comparative Example 9.
  • FIG. 18 is a view showing a SEM photograph of particles obtained in Comparative Example 10.
  • FIG. 19 is a view showing a SEM photograph of particles obtained in Comparative Example 11.
  • FIG. 20 is a view showing a SEM photograph of the particles obtained in Comparative Example 12.
  • FIG. 21 is a diagram showing a particle size distribution histogram of particles obtained in Example 1.
  • FIG. 22 is a diagram showing a particle size distribution histogram of particles obtained in Example 2.
  • FIG. 23 is a diagram showing a particle size distribution histogram of particles obtained in Example 3.
  • FIG. 24 is a diagram showing a particle size distribution histogram of particles obtained in Example 4.
  • FIG. 25 is a diagram showing a particle size distribution histogram of particles obtained in Example 5.
  • FIG. 26 is a diagram showing a particle size distribution histogram of particles obtained in Example 6.
  • FIG. 27 is a diagram showing a particle size distribution histogram of particles obtained in Example 7.
  • FIG. 28 is a diagram showing a particle size distribution histogram of particles obtained in Example 8.
  • FIG. 29 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Example 1.
  • FIG. 30 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Examples 2 and 3.
  • FIG. 31 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Example 4.
  • FIG. 32 is a graph showing a particle size distribution histogram of particles obtained in Comparative Example 11.
  • FIG. 33 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Example 12.
  • the present invention relates to a method for producing silver nanoparticles by reacting an amine compound (b) complexed with a thermally decomposable silver compound (a) to produce a silver nanoparticle, wherein the amine compound has (i) a linear structure It is characterized in that (ii) an amino alcohol having one amino group and one hydroxyl group at one end of the linear molecule and (iii) one or more ether bonds in the linear structure.
  • a specific amino alcohol silver nanoparticles having a wide distribution and relatively large particle size can be easily obtained, and in particular, it is easy to synthesize silver nanoparticles in a large particle size range of 200 to 500 nm. Also, it is excellent in environment because the amount of use of the entire amine compound can be reduced. The details will be described below.
  • a thermally decomposable silver compound is used as a starting material.
  • the thermally decomposable silver compound refers to a silver compound which is complexed with the component (b) described later and thermally decomposed under heating conditions which are possible with ordinary equipment.
  • silver oxalate, silver nitrate, silver acetate, silver carbonate, silver oxide, silver nitrite, silver benzoate, silver cyanate, silver citrate, silver lactate and the like can be applied.
  • silver carbonate or silver oxalate (Ag 2 C 2 O 4 ) is particularly preferable.
  • silver oxalate is silver oxalate.
  • Silver oxalate can be decomposed at relatively low temperatures without the need for a reducing agent to produce silver particles.
  • carbon dioxide generated by the decomposition is released as a gas, so that no impurities are left in the solution.
  • an amine compound capable of forming a complex with a silver compound is used as the component (b).
  • This compound has the function of forming a complex with the silver compound to lower the thermal decomposition temperature of the silver compound and enabling silver particles to be formed at a low temperature.
  • the organic group possessed by the amine compound has the function of a protective agent to have the effect of the dispersion stability of silver particles.
  • Such an amine compound is not particularly limited as long as it is an amine compound that can form a complex with a silver compound.
  • the number of hydrogen atoms bonded to the amino group of the amine compound is preferably one or two, that is, a primary amine (RNH 2 ) or a secondary amine (R 2 NH).
  • Such formation of silver particles from a silver compound and an amine compound that can be complexed with the silver compound is known as described in the background art.
  • aliphatic hydrocarbon amine compounds such as "aliphatic hydrocarbon monoamines” and “aliphatic hydrocarbon diamines” which have been used as amine compounds in the known art.
  • alkylamine, alkoxyamine, alkyl ether amine is mentioned.
  • n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine and the like can be mentioned as the alkylamine.
  • alkylamine has a strong irritating odor, and there is a risk of being discharged at high temperature together with carbon dioxide gas during the decomposition reaction. Therefore, when it is desired to suppress the irritating odor, use an amine compound containing an oxygen atom.
  • amine compounds containing an oxygen atom are alkoxyamines, alkyl ether amines, and amino alcohols. According to the study of the present inventor, the amine compound containing these oxygen atoms not only can suppress the irritating odor but, among them, the specific amino alcohol described below in particular has excellent physical properties of the obtained silver particles. found.
  • the present invention is characterized by using the following as an amine compound which can be complexed with the silver compound which is the component (b). That is, (i) a linear structure, and (ii) one amino group and one hydroxyl group at each end of the linear molecule, and (iii) one or more ether bonds in the linear structure It is characterized by using the amino alcohol (b1) which it has.
  • These amine compounds have the function of lowering the thermal decomposition temperature of the silver compound and forming silver particles at a low temperature by forming a complex with the silver compound. Furthermore, in the present invention, it is possible to easily make the obtained silver particles have a large and wide distribution.
  • the obtained silver nanoparticles have a relatively large particle size and a broad particle size distribution. It is The silver nanoparticles having a large particle size and a wide distribution have excellent effects as described later.
  • the series number of the amino group of the amine compound (b1) is not limited, and any of primary amines, secondary amines or tertiary amines can be used, but in particular, primary or secondary ones are preferable because they tend to form a complex.
  • the amine compound (b1) has (i) a linear structure.
  • “linear” means that a carbon atom constituting an amine compound and a hetero atom are linearly connected and have no branch. It has an amino group and a hydroxyl group respectively at both ends of the linear structure of the carbon atom and the hetero atom.
  • (iii) have one or more ether bonds in the linear structure.
  • the number of ether bonds is not limited as long as it is one or more.
  • the carbon number of the amino alcohol of the component (b1) is not limited, but is preferably 4 or more. Usually, it has 4 to 7 carbon atoms. The above-mentioned excellent effects are the best in this range. That is, the particle size of the obtained silver particles is large and the particle size distribution is broad. Presumably, when the number of carbon atoms is 4 or more, the difference in excluded volume in steric hindrance between the two coordination models in the mechanism described later becomes large, so it is speculated that the particles grow large and the particle size distribution becomes broad. .
  • Examples of the amino alcohol satisfying the above conditions include diglycolamine, 3- (3-aminopropoxy) propanol and 2- [2- (3-aminopropoxy) ethoxy] ethanol.
  • it is diglycolamine.
  • the above component (b1) may be used alone or in combination of two or more.
  • the following model is considered about the coordination state of the silver atom of the specific amino alcohol which is (b1) component.
  • a model in which an amino group is coordinated to a silver atom and an alkyl chain is linearly oriented to the outside (dispersion medium side) (Fig. 1-1)
  • the oxygen atom in the ether bond in the model is also a model that approaches and stabilizes on the silver atom side (Fig. 1-2). Due to the existence of these two coordination models, the steric hindrance by the amine compound around the silver atom is not uniform. For this reason, it is thought that dispersion occurs in the particle diameter to be produced, and the particle diameter is formed widely from large particle diameter to small particle diameter.
  • alkylamines that have been used in the prior art are only linearly oriented since only the amino group has electron donating properties, as shown in FIG. 1-3. Therefore, the variation of particles is hard to occur. This is considered to be the reason why only silver particles with uniform particles can be synthesized.
  • an amine compound containing an oxygen atom particularly an amino alcohol having 3 to 4 carbon atoms (b2) can be used in combination with the component (b1).
  • the component (b2) is preferable because the effect of increasing the particle diameter and broadening the particle size distribution can be further enhanced. More preferably, it is (i) a branched primary amino alcohol having 3 to 4 carbon atoms, (ii) having one amino group and one hydroxyl group, and (iii) via an alkyl chain having 2 carbon atoms. An amino group and a hydroxyl group, or iv) a linear secondary amino alcohol having 3 carbon atoms.
  • amino alcohols having 4 or less carbon atoms which satisfy the above conditions include 1-amino-2-butanol, DL-1-amino-2-propanol, 2-amino-, and the like as amino alcohols satisfying (i) to (iii).
  • Examples include 2-methyl-1-propanol (hereinafter AMP) and DL-2-amino-1-propanol.
  • AMP 2-methyl-1-propanol
  • N-methyl ethanolamine is mentioned as an amino alcohol which satisfy
  • AMP which is an amino alcohol satisfying (i) to (iii), 1-amino-2-butanol, DL-1-amino-2-propanol, and DL-2-amino-1-propanol are particularly preferred. It is most preferred as it is easy to handle, complex formation in the presence of polar solvents such as alcohol solvents occurs easily, and silver particles of large particle size and wide particle size distribution can be easily obtained. Among these, AMP is the most effective and superior.
  • the above component (b2) may be used alone or in combination of two or more.
  • Amine compound (b3) having a dispersion stabilization effect by steric hindrance in the present invention, at the time of the complex formation of (a) and (b), an amine compound other than the components (b1) and (b2) described above can be present.
  • This component has a function of imparting the dispersion stability effect of silver particles by the steric hindrance effect.
  • the amine compounds other than the components (b1) and (b2) those having a molecular length of 5 ⁇ or more are particularly preferable. That is, it is an amine compound which has a molecule length of 5 ⁇ or more and does not meet the requirements of (b1) and (b2) described above.
  • the length of the molecule is the distance of the longest two atoms that do not contain hydrogen atoms.
  • the length of this molecule can be determined by calculation.
  • the calculation conditions are density functional theory, function ⁇ B97X-D, basis function 6-31 + G *, environment in vacuum energy state, ground state, and can be calculated with various molecular calculation software such as SPARTAN ⁇ 16V 1, 1, 0.
  • the length of the molecule is preferably 7 ⁇ or more. However, if the length is too long, the boiling point becomes high and removal becomes difficult, so the thickness is preferably 8 ⁇ or less.
  • amine compounds having a main chain (main skeleton) composed of 7 atoms or more including amino groups are preferable.
  • the number of hydrocarbon groups bonded to the amino group of the amine compound is not limited, but one or two primary amines or secondary amines are preferred because they are particularly susceptible to coordinate bonding with silver.
  • component (b3) include aliphatic hydrocarbon monoamines having 4 or more carbons in total.
  • the aliphatic hydrocarbon monoamine having 4 or more carbon atoms is often used in the method of forming a complex with the silver compound described in the prior art to form silver nanoparticles.
  • aliphatic hydrocarbon monoamines having 4 or more carbon atoms have a strong irritating odor and there is a risk of being discharged together with carbon dioxide gas at the time of decomposition reaction
  • other amine compounds may be used. Specifically, it is an amine compound (alkoxyamine, alkyl ether amine, amino alcohol) containing an oxygen atom and having 4 or more carbon atoms, and (i) to (iii) or (iv) described above as the component (b2) It is something that does not affect.
  • the above component (b3) include n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine and the like as the alkylamine.
  • alkoxyamine 3-methoxypropylamine, 3-ethoxypropylamine and the like can be mentioned.
  • the alkyl ether amines include M series of JEFFAMINE manufactured by HUNTSMAN, M-600, M-1000, M-2005, M-2070 and the like.
  • the amino alcohol include 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol and the like.
  • alkylamine More preferable examples of the alkylamine include n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine and the like.
  • alkoxyamine 3-methoxypropylamine, 3-ethoxypropylamine and the like can be mentioned.
  • amino alcohols include 5-amino-1-pentanol, 6-amino-1-hexanol and the like.
  • the above component (b3) may be used alone or in combination of two or more.
  • (3-1. Molar ratio in amine compound (b2) / (b)) (B2) / (b) is preferably 0.3 to 0.8 (molar ratio), preferably 0.4 to 0.8. This range is most suitable for producing large sized, high distribution silver nanoparticles.
  • the molar ratio is smaller than 0.3, the amount of addition of the amine compound having a long molecule length increases, the particles become small overall, and the particle size distribution tends to be narrow, which is not preferable.
  • the molar ratio is larger than 0.8, the steric hindrance effect as the protective agent is weakened, and the risk that the silver particles are fused at the time of synthesis is increased.
  • the molar ratio (amine compound / silver atom of the silver compound) is 0.7 to 2.0 so that the amine compound (b) It is desirable to adjust the amount. By doing so, variations in particle size occur, and it is easy to obtain silver particles in the target particle size range. More preferably, it is 0.7 to 1.5, still more preferably 0.7 to 1.3, and most preferably 0.7 to 1.3.
  • the molar ratio of silver atoms in the amine compound / silver compound is 2.0 or more.
  • the amount of amine discharge can also be small. Therefore, it is possible to reduce the risk of human body and environmental load due to the release of amine from the system.
  • such a conventional method makes it easy to synthesize particles having a small particle diameter and a narrow distribution, but in the present invention, silver particles having a wide distribution and a large particle diameter can be obtained.
  • the molar ratio is less than 0.7, flat particles are easily formed and easily aggregated, so that the dispersion stability of the silver coating composition becomes low.
  • alcohol solvents are preferable, and alcohols having 3 to 12 carbon atoms are particularly preferable.
  • n-propanol (bp bp: 97 ° C.), isopropanol (bp: 82 ° C.), n-butanol (bp: 117 ° C.), isobutanol (bp: 107.89 ° C.), sec-butanol (bp: 99.
  • n-butanol, n-hexanol, and n-decanol are preferable in consideration of the fact that the temperature of the thermal decomposition step of the complex compound to be performed later can be increased and the convenience in post-treatment after formation of silver nanoparticles is taken into consideration. .
  • These may be used alone or in combination of two or more.
  • the organic solvent is 80 to 130 parts by weight (that is, the weight ratio of the organic solvent (c) to the silver compound (a)) with respect to 100 parts by weight of the silver compound (a) for sufficient stirring operation of each component. What mixed the organic solvent so that (c) / (a) may be 0.8-1.3 is preferable. More preferably, it is 80 to 125 parts by weight with respect to 100 parts by weight of the silver compound.
  • the slurry represents a mixture in which a solid silver compound is dispersed in an organic solvent or a mixture of an organic solvent and an amine compound.
  • a mixture of an organic solvent and an amine compound may be charged into a reaction vessel, and a silver compound may be added thereto.
  • Silver oxalate has been reported to be explosive in the dry state. Therefore, when using silver oxalate as a silver compound, it is preferable to use what was made into the wet state. The wet state significantly reduces the detonability and facilitates the handling. Therefore, water or the above-mentioned organic solvent may be mixed and used in a wet state.
  • aliphatic carboxylic acid [5. About aliphatic carboxylic acid] Moreover, you may use aliphatic carboxylic acid at the time of complex formation for adjustment of particle diameter and particle size distribution. The addition of the aliphatic carboxylic acid tends to reduce the particle size and narrow the particle size distribution. It is desirable to adjust the water content appropriately and use it.
  • the aliphatic carboxylic acid may be used together with the amines, and may be added and used when mixing a silver compound and an amine. As the aliphatic carboxylic acid, a saturated or unsaturated aliphatic carboxylic acid is used.
  • saturated aliphatic monocarboxylic acids having 4 or more carbon atoms such as icosanoic acid and eicosenic acid
  • unsaturated aliphatic monocarboxylic acids having 8 or more carbon atoms such as oleic acid, elaidic acid, linoleic acid, and palmitoleic acid.
  • C 8-18 saturated or unsaturated aliphatic monocarboxylic acids are preferable.
  • the number of carbon atoms By setting the number of carbon atoms to 8 or more, when the carboxylic acid group is adsorbed on the surface of the silver particles, a space between the silver particles and the other silver particles can be secured, so that the effect of preventing aggregation of silver particles is improved.
  • a saturated or unsaturated aliphatic monocarboxylic acid compound having up to 18 carbon atoms is usually preferred.
  • octanoic acid, oleic acid and the like are preferably used.
  • the aliphatic carboxylic acids only one type may be used, or two or more types may be used in combination.
  • the aliphatic carboxylic acid may be, for example, about 0.05 to 10 moles, preferably 0.1 to 5 moles, and more preferably about 1 mole to 1 mole of silver atoms of the silver compound as a raw material. It is preferable to use 0.5 to 2 moles.
  • the amount of the aliphatic carboxylic acid is less than 0.05 mol with respect to 1 mol of the silver atom, the effect of particle diameter control by the addition of the aliphatic carboxylic acid is weak.
  • the particle diameter may be too small and may remain even in the washing or surface protection agent replacement step, so low temperature baking is preferable. It becomes difficult to remove the aliphatic carboxylic acid. However, aliphatic carboxylic acid may not be used.
  • water may be used together with the amine compound of the component (b1).
  • the water content of the reaction system is preferably in the range of 5 to 20 parts by weight or less with respect to 100 parts by weight of the silver compound. Particularly preferably, it is at most 15 parts by weight.
  • the water content depends on the kind of amine compound used for complex formation, but when the water content is small, the particle size distribution of the obtained silver particles is uniform, and voids of the sintered body are produced, which is expected in the present invention May be difficult to develop.
  • the silver particles become too coarse, and portions where the particles sinter and coalesce are generated, which is not preferable.
  • water to be used ion-exchanged water with reduced metal ion impurities is preferred.
  • Water may be added before the heating step, and may be added at any stage before the formation of the silver-amine complex or after the complex formation.
  • the ratio of the organic solvent (c) to water described above is preferably such that the weight ratio of water / organic solvent is 0.03 to 0.3. More preferably, it is 0.1 to 0.25. Within this range, in particular, it is easy to obtain the effects of the present invention.
  • the silver particles themselves may be enlarged, and the adjacent particles may be sintered and coalescence. It is presumed that this is because water inhibits the adsorption of the silver atom of the amine and the silver particles are enlarged.
  • the amine compound (b) to be complexed is placed in the polar solvent (c) and mixed. If necessary, aliphatic carboxylic acid and water can be added and mixed to adjust the liquid raw material necessary for the reaction.
  • the heating temperature is preferably 100 ° C. or less, preferably 80 ° C. or less, more preferably 60 ° C. or less, and the configuration of the liquid raw material to be liquefied is desirable.
  • the temperature is higher than the above temperature range, when the slurry is mixed with a silver compound, a partial complexation / oxalic acid decomposition reaction starts first, and the silver nanoparticles are not obtained while maintaining the uniformity in the system. It may be generated.
  • a silver compound and a predetermined amount of an amine mixture, or, if necessary, an aliphatic carboxylic acid and water are mixed.
  • the mixing at this time may be carried out while stirring at room temperature, or the coordination reaction (complexation reaction) of the silver compound with the amine with an amine is accompanied by heat generation and appropriately cooled while stirring below room temperature.
  • the mixed solution of the silver compound and the amine compound and the like is performed in the presence of a polar solvent, so that stirring and cooling can be well performed.
  • the excess of polar solvent and amine compound acts as a reaction medium.
  • the odor of the highly volatile alkylamine has a great adverse effect on the working environment.
  • the amount of highly volatile alkylamine used at the time of silver nanoparticle synthesis can be reduced or eliminated. Can reduce odor and exposure to workers when preparing the highly volatile alkylamine.
  • the complex compound to be formed generally exhibits a color corresponding to its constituent components, the progress of the reaction for forming the complex compound can be detected from the change in color of the reaction mixture. In the case where confirmation is difficult due to a change in color, the generation state can be detected by a change in viscosity of the reaction mixture or a change in temperature. In this way, a silver amine complex is obtained in a polar solvent and a medium based on an amine compound.
  • the heating rate affects the particle size of the deposited silver particles, so that the particle size of the silver particles can be controlled by adjusting the heating rate of the heating process.
  • washing solvent In washing of the silver particles, it is preferable to use, as a solvent, an alcohol having a boiling point of 150 ° C. or less such as methanol, ethanol or propanol. And as a detailed method of washing, after adding a solvent to a solution after silver particle synthesis and stirring until suspension, it is preferable to remove the supernatant liquid by decantation. The amount of amine removed can be controlled by the volume of solvent added and the number of washes. In the case where the above-described series of operations is performed once in the number of lines, preferably, washing is performed 1-5 times using a solvent having a volume of 1/20 to 3 times that of the solution after silver particle synthesis.
  • an amine compound suitable for the application is substituted for the above-mentioned silver nanoparticles by the step of substituting a surface protective agent with an amine compound having 4 or more carbon atoms (which may contain an oxygen atom).
  • the amine compound to be finally substituted may be one used when producing silver nanoparticles, or one not used may be newly used.
  • the surface protective agent of the silver particles is replaced by stirring and suspending the washed silver particles for a certain period of time in the amine compound to be finally substituted. At that time, 50 to 100 wt% of the amine compound to be finally substituted is added to the contained pure silver, and the mixture is stirred and suspended for about 1 hour under normal temperature.
  • the confirmation of a surface protection agent is possible by the difference of the sintering origin peak in DTA measurement, head space GC / MS, etc.
  • the target silver particles are obtained through the washing step again.
  • the amine compound used here is an alkylamine having 4 to 8 carbon atoms or an amine compound containing an oxygen atom (alkoxyamine, alkyl ether amine, amino alcohol). Among them, those having a molecule length of 5 to 8 ⁇ are preferable, and those having a molecule length of 7 to 8 ⁇ are more preferable.
  • the alkylamine and the amine compound containing an oxygen atom can be used alone or in combination of two or more kinds, and depending on the composition thereof, it is also possible to adjust the viscosity when processed into a paste.
  • Silver nanoparticles are formed in which the amine compound used is bound as a protective agent.
  • Silver nanoparticles refer to fine particles having a particle size of usually 1 to 1000 nm mainly composed of a silver component, which can be produced by the following method.
  • the protective agent includes, for example, the amino alcohol (b) having the specific carbon number of 4 or less, further includes an amine compound (d) having a molecular length of 5 ⁇ or more, and the aliphatic carbon when used. Contains acid. Their content in the protective agent is equivalent to their use in the amine mixture. In addition, it is possible to adjust the type and total amount of the protective agent by the washing step, and if necessary, the protective agent replacement step.
  • the length of the molecule of the amine compound finally bonded as a protecting agent is preferably 2 to 8 ⁇ , more preferably 5 to 8 ⁇ . And, 7-8 ⁇ is most preferable.
  • the total amount of the protective agent is preferably 0.3 to 2.0 parts by weight with respect to 100 parts by weight of pure silver. More preferably, it is 0.5 to 1.0 parts by weight.
  • the silver nanoparticles of the present invention generally have a particle size of 1000 nm or less. Also, the average particle size is 70 to 350 nm, preferably 70 to 300 nm, and more preferably 80 to 200 nm. The coefficient of variation indicating the variation in particle diameter is made to be 30 to 80%, preferably 40 to 70%, and more preferably 50 to 60%.
  • the average particle size and the coefficient of variation are determined as follows.
  • the particle shape of the obtained silver nanoparticles is observed by FE-SEM. Thereafter, using the image analysis software SCANDIUM (manufactured by OLYMPUS), the particle diameters of 300 or more particles were measured, and the values of the average particle diameter and the standard deviation were determined by analysis. Using these values, the coefficient of variation was calculated based on the following formula.
  • Coefficient of variation (%) ⁇ standard deviation (nm) / average particle size (nm) ⁇ x 100
  • the equipment for measuring the particle size is not limited as long as the same results as those described above can be obtained.
  • coating a silver coating material can be thickened. Specifically, a thick film of 10 to 30 ⁇ m can also be obtained. In addition to being thick, the volume resistivity of the resulting film can also be lowered. Specifically, a volume resistivity of about 20 to 30 ⁇ ⁇ cm can be obtained with a thick film of 20 ⁇ m or more. This is because silver particles are highly filled and a film with a high content of silver particles is obtained by being closely packed with close-packing between large particles with a wide particle size distribution. It is guessed.
  • the average particle size is less than 70 nm, the amount of amine compound protecting the surface of silver particles is increased, and it is difficult to lower the volume resistivity of the obtained coating.
  • the average particle size exceeds 350 nm, the phenomenon of melting point depression of silver nanoparticles weakens and it becomes difficult to sinter at low temperature, so it is also difficult to lower the volume resistivity of the coating in this case. If the coefficient of variation is less than 30%, the particles become uniform, and the gaps between the particles can not be filled, making it difficult to lower the volume resistivity of the coating.
  • the coefficient of variation exceeds 80%, even if there is particle dispersion, the particle size will be too different, and in this case it is also difficult to fill the gaps between particles, and in this case also the volume resistivity of the coating It will be difficult to lower it.
  • the viscosity is suitable as a silver coating composition. It can be adjusted.
  • the viscosity of the screen printing ink is preferably in the range of 0.1 to 500 Pa ⁇ s (at a shear rate of 51 / sec). If it is too high, there is no flowability and printing defects are likely to occur, and if it is too low, the printed ink will sag and the line width will spread. Therefore, in order to increase the viscosity, an organic binder is usually added in many cases, but the organic binder raises the resistance value of the obtained coating film.
  • the silver particles of the present invention can have a relatively high viscosity even when 1 wt% of Etocel 45 (manufactured by Nisshin Kasei Co., Ltd.) is added to the pure silver as an organic binder.
  • the viscosity can be adjusted to about 30 to 40 Pa ⁇ s by adjusting to about 80 nm and the coefficient of variation to about 35%. Therefore, even if the addition amount of the organic binder is 1 wt% or less based on the pure silver content, the viscosity suitable for the above screen printing can be obtained.
  • the viscosity can be controlled by adjusting the particle size, the degree of freedom of the addition amount of the organic binder can be increased and the amount can be reduced, which is very excellent.
  • the production method of the present invention can control the particle size depending on the type of amine used, the type of organic solvent, the amount of water added, and the like. Therefore, it is also suitable for industrial production, for example, silver particles in the large particle size range of 200 to 500 nm and silver particles in the small particle size range of 50 to 200 nm can be synthesized in one batch.
  • silver particles obtained in this way have silver particles in the large particle size region of 200 nm or more, they are aggregated (baked out during the processes such as cleaning / substituting agent substitution / pasting of excess protective agent of silver nanoparticles as well). It can be expected that the silver nanoparticle dispersion / silver paint composition can be easily produced without being hard to break and impairing the original characteristics of the silver particles. This is also effective when scaling up is considered.
  • a silver nanoparticle dispersion can be produced using the silver nanoparticles obtained by the method described above.
  • the silver nanoparticle dispersion refers to a composition containing at least silver nanoparticles and a dispersion medium.
  • Such silver nanoparticle dispersions can take various forms without limitation.
  • a silver nanoparticle dispersion can be obtained by dispersing silver nanoparticles in a suitable organic solvent (dispersion medium) in a suspended state.
  • the silver nanoparticles obtained in the present invention are excellent in dispersibility, and can be stably present in the dispersion medium at high concentration.
  • the content of silver nanoparticles in the composition can be contained at a high concentration of 70 to 95% by weight, more preferably 75 to 80% by weight, and it can be in the so-called paste state.
  • a silver coating composition can be produced which contains a so-called binder component.
  • Dispersion medium of dispersion or coating composition Various organic solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, dodecane, tridecane, tetradecane and the like can be used as a dispersion medium for obtaining a silver nanoparticle dispersion or a silver coating composition.
  • Alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; aromatic hydrocarbon solvents such as toluene, xylene, mesitylene and the like; methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, n- Alcohol solvents such as heptanol, n-octanol, n-nonanol, n-decanol, n-dodecanol etc. may be mentioned.
  • an organic solvent having 8 to 16 carbon atoms and an oxygen atom in the structure and having a boiling point of 280 ° C. or less is preferable.
  • the target of the sintering temperature of silver particles is 150 ° C. or less, the solvent having a boiling point of 280 ° C. or more is difficult to volatilize and remove.
  • this solvent examples include terpineol (C10, boiling point 219 ° C.), dihydroterpineol (C10, boiling point 220 ° C.), texanol (C12, boiling point 260 ° C.), ethyl carbitol acetate (C8, boiling point 219 ° C.), butyl Carbitol acetate (C10, boiling point 247 ° C.), 2,4-dimethyl-1,5-pentanediol (C9, boiling point 150 ° C.), 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (C16, Boiling point 280 ° C.).
  • the solvent may be used as a mixture of two or more kinds, or may be used alone.
  • the type and amount of the organic solvent may be appropriately determined in accordance with the concentration and viscosity of the desired silver coating composition or silver nanoparticle dispersion.
  • An organic binder may be added to the silver coating composition in order to aid the dispersibility of silver particles or to provide adhesion to a substrate.
  • the addition amount of the organic binder is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of contained silver.
  • the form of the binder resin in the conductive ink may be dissolved in a solvent, or may be an emulsion or a suspension.
  • the binder resin is not particularly limited.
  • polyester resin polyurethane resin, polyamide resin, polyvinyl chloride resin, polyacrylamide resin, polyether resin, acrylic resin, melamine resin, vinyl resin, phenol resin, epoxy resin, urea Resin, vinyl acetate resin, polybutadiene resin, vinyl vinyl acetate copolymer resin, fluorine resin, silicone resin, rosin, rosin ester, chlorinated polyolefin resin, modified chlorinated polyolefin resin, chlorinated polyurethane resin, cellulose resin, polyethylene
  • the binder resin to be used may be used individually by 1 type, and may be used in combination of 2 or more types.
  • the baking can be performed at a temperature of 200 ° C. or less, for example, room temperature (25 ° C.) or more and 150 ° C. or less, preferably room temperature (25 ° C.) or more and 120 ° C. or less.
  • a temperature of 60 ° C. to 200 ° C. for example, 80 ° C. to 150 ° C., preferably 90 ° C. to 120 ° C.
  • the baking time may be appropriately determined in consideration of the coated amount of silver ink, baking temperature, etc., for example, within several hours (for example, 3 hours or 2 hours), preferably within 1 hour, more preferably within 30 minutes.
  • the silver nanoparticles are configured as described above, sintering of silver particles proceeds sufficiently even with such a low temperature and short time baking process. As a result, excellent conductivity (low resistance value) is exhibited even when the average particle diameter exceeds 200 nm.
  • a silver conductive layer having a low resistance value eg, 20 to 30 ⁇ ⁇ cm is formed. The resistance value of bulk silver is 1.6 ⁇ cm.
  • polyester-based materials such as polyethylene terephthalate (PET) film and polyethylene naphthalate (PEN) film as well as glass substrates and heat-resistant plastic substrates such as polyimide-based films can be used as substrates.
  • PET polyethylene terephthalate
  • PEN polyethylene naphthalate
  • a low heat resistant general purpose plastic substrate such as a film or a polyolefin-based film such as polypropylene can also be suitably used.
  • the baking for a short time reduces the load on the low-heat-resistance general-purpose plastic substrate and improves the production efficiency.
  • the thickness of the silver conductive layer may be appropriately determined in accordance with the intended application, and particularly high conductivity can be obtained even when the silver conductive layer having a relatively large film thickness is formed by using the silver nanoparticles according to the present invention. Can be shown.
  • the thickness of the silver conductive layer may be selected, for example, in the range of 100 nm to 30 ⁇ m, preferably 1 ⁇ m to 20 ⁇ m, and more preferably 10 ⁇ m to 20 ⁇ m.
  • the silver conductive material obtained by the silver nanoparticle dispersion or silver paint composition of the present invention includes an electromagnetic wave control material, a circuit board, an antenna, a heat sink, a liquid crystal display, an organic EL display, a field emission display (FED), an IC card,
  • the present invention can be applied to an IC tag, a solar cell, an LED element, an organic transistor, a capacitor (capacitor), an electronic paper, a flexible battery, a flexible sensor, a membrane switch, a touch panel, an EMI shield, and the like.
  • Example 1 Manufacturing of silver particles
  • 7.58 g (24.95 mmol) of a dried silver oxalate product as a silver compound as a raw material and 9.21 g (90.14 mmol) of n-hexanol as a polar solvent are stirred in a test tube set in an aluminum block heating stirrer.
  • the silver oxalate was allowed to wet.
  • 2.11 g (28.09 mmol) of DL-1-amino-2-propanol and 0.30 g (1.06 mmol) of oleic acid were added. Thereafter, the mixture was stirred for 1 hour to produce a silver-amine complex.
  • the particle ratio (%) of 100 to 200 nm of particles, the average particle diameter (nm), and the variation coefficient (%) are shown in Table 5.
  • An FE-SEM photograph is shown in FIG.
  • the particle size distribution histogram is shown in FIG.
  • Examples 2 to 8, Comparative Examples 1 to 12 Manufacturing of silver particles
  • the materials used and the mixing ratio are as shown in Table 5-12
  • the temperature rising rate after formation of the silver-amine complex compound is as shown in Table 5-12
  • the reaction vessel / heating device is as shown in Table 5
  • Silver particles were produced in the same manner as in (Production of silver particles) in Example 1 except for using those shown in 13.
  • the protective agent substitution process is shown below.
  • Example 2 The obtained silver particles were subjected to the same method as in Example 1 (confirmation of particle diameter).
  • Comparative Examples 2 to 4 the particle diameter was confirmed by STEM images.
  • Example 2 to 8 and Comparative Examples 1, 2, 11 and 12 the obtained particles were used in the same manner as in Example 1 (silver nanoparticle paste, ink preparation and baking). .
  • Example 8 the particles before the protective agent substitution treatment and the particles after the protective agent substitution treatment were used (preparation of silver nanoparticle paste, ink and baking).
  • the silver nanoparticle dispersion was applied onto glass by spin coating.
  • the average particle diameter (nm), variation coefficient (%) and particle ratio (%) in each particle diameter range of the obtained particles are shown in Tables 2 to 8 and Comparative Examples 1 to 4, 11 and 12 It shows in 5-12. SEM or STEM images are shown in FIGS. The particle size distribution histograms of Examples 2 to 8 and Comparative Examples 1 to 4, 11 and 12 are shown in FIGS. With respect to Examples 1 to 10 and Comparative Examples 1 to 4, values of volume resistivity and film thickness of the sintered coating are shown in Tables-5 to 12.
  • the present invention it is possible to form a sintered coating film of 20 ⁇ m or more by adding the amine compound of the component (b) at the time of complex formation and using the synthesized silver particles, and It was confirmed that the film having a volume resistivity of 50 ⁇ ⁇ cm or less and a conductive film can be obtained under the sintering conditions at ° C.
  • Examples 1 to 3 diglycolamine and the amine compound of component (b2) are used in combination.
  • AMP is used in Example 3
  • the variation coefficient also greatly varies and the ratio of particles having a small particle diameter increases, and a fired film having the lowest volume resistivity is obtained at each firing temperature.
  • the addition amount of diglycolamine was increased or decreased, but in Example 4 in which the addition amount was large, particles having a particle diameter larger than Example 3 were obtained. And although the average particle diameter became large, it turned out that the volume resistivity of the sintering coating film in each calcination temperature hardly changes.
  • the diglycolamine is used in the case where the amine of the component (b2) and the short-chain alkylamine or the alkyldiamine are used, and in any of the examples, the average particle diameter is relatively 200 nm or more. It was possible to form a large particle size. Among them, in Example 4 using AMP, particles having the largest variation coefficient and variation were obtained. In Examples 7 and 8, AMP and diglycolamine were used, and in Example 8, water was additionally used. Then, the particle size was further increased. Moreover, the volume resistivity of the sintered coating at each temperature did not decrease even when the particle diameter was increased.
  • Example 8 when the volume resistivity of the sintering coating film before and behind a hexylamine substitution process was evaluated, it was substantially equivalent performance. Since the polarity of the protective group can be changed, it was possible to synthesize particles having a wide range that can cope with the dispersibility in various solvents.
  • Comparative Example 1 is a silver particle when diglycolamine or the amine compound of component (b2) is not used, but the particle diameter is relatively small with an average particle diameter of 64 nm and a variation coefficient of 20.3%. Of particles were formed. As a result, in the case of a thick-film sintered film of about 20 ⁇ m, the resistance value was significantly increased. Since a small particle size requires many protective agent components, it is considered that the protective agent remains and becomes a resistant component in a thick film.
  • Comparative Example 2 in which the particles of Comparative Examples 2 to 4 prepared by the method equivalent to the manufacturing methods of Patent Documents 1 and 2 were evaluated as texanol paste, volume shrinkage occurred violently after firing, and the entire coating was cracked. Has occurred. Moreover, in Comparative Examples 3 and 4 coated in a low viscosity dispersion state as in Patent Documents 1 and 2, a sintered coating film of about 0.5 ⁇ m was formed, and it was difficult to form a thick film.
  • Comparative Examples 5 to 10 evaluation was performed on an amine compound having a similar structure to diglycolamine.
  • the particles aggregate during synthesis, and it has not been possible to obtain silver particles in a dispersible state. These are considered to cause aggregation because particles are adsorbed between particles if the adsorption with silver particles is strong and there are two or more amino groups or carboxylic acids in the molecule.
  • the hydroxyl group does not completely adsorb to silver particles, it has an polarity that allows it to approach silver particles, so that amino alcohol and component (b1) having an ether bond in the molecule, especially diglycolamine, It is thought that the effect as a protective agent which can be synthesized without aggregating silver particles can be expressed.
  • the silver nanoparticles of the present invention can easily form particles having an average particle diameter of 200 nm or more by the method of the present invention
  • a silver coating composition which can easily obtain a low resistance thick film conductive film by giving a suitable dispersion to the particle size distribution.
  • the present invention it is possible to easily form a silver conductive layer having a large particle size and a wide distribution, a thick film and high conductivity by a method in which the amount of strongly irritating amine discharged is suppressed. Nanoparticles can be obtained.

Abstract

[Problem] To provide a method with which silver nanoparticles having excellent physical properties are obtained, and with which the discharged amount of amines with a strong irritant odour is restricted. [Solution] A method for producing silver nanoparticles, said method comprising reacting a thermally decomposable silver compound (a) and an amine compound (b) that can form a complex with (a) and thereby forming a complex, and heating the obtained complex to cause the thermal decomposition thereof and thereby forming the silver nanoparticles, said method being characterised in that (b) is an amino alcohol (b1) that is a linear amino alcohol, has one each of an amino group and a hydroxyl group at both ends of the linear molecule of said amino alcohol, and has an ether bond in the linear molecule structure.

Description

広分布な粒度分布を持つ銀ナノ粒子の製造方法及び銀ナノ粒子Method of producing silver nanoparticles with broad distribution of particle size distribution and silver nanoparticles
　本発明は、粒度分布が広く、エーテル結合を有する特定のアミノアルコールが保護剤として結合した銀粒子の製造方法及び銀ナノ粒子に関する。 The present invention relates to a method for producing silver particles having a broad particle size distribution and in which a specific amino alcohol having an ether bond is bound as a protective agent, and silver nanoparticles.
　銀ナノ粒子は、金属ナノ粒子の融点降下の性質により、低温でも焼結するため、基板上への電気配線や、パワーデバイス半導体の接合材として利用されている。しかし、銀ナノ粒子は微細であることから凝集しやすく、また融点降下により融着しやすいため、銀ナノ粒子の表面には保護剤と呼ばれる有機物層を存在させている。これらの有機物層は、脂肪酸やアルキルアミン等が用いられることが多いが、特にアルキルアミンまたはアルキルジアミンで被覆された銀ナノ粒子は比較的低温で保護剤が脱離し、低温焼成可能な銀ナノ粒子として知られている（特許文献１～２）。 Silver nanoparticles are used as electrical wiring on a substrate or as a bonding material for power device semiconductors because they sinter at low temperature due to the melting point lowering property of metal nanoparticles. However, silver nanoparticles are easily aggregated due to their fineness, and they are easily fused due to the decrease in melting point, so an organic layer called a protective agent is present on the surface of silver nanoparticles. In these organic layers, fatty acids, alkylamines and the like are often used, but particularly silver nanoparticles coated with alkylamines or alkyldiamines release protective agents at relatively low temperatures, and silver nanoparticles that can be baked at low temperatures (Patent Documents 1 and 2).
　このような低温焼成可能な銀ナノ粒子を用いた焼成塗膜を配線などの導電材料としての利用が期待されるが、配線等の導電材料としての信頼性や導電性を担保するために、配線を厚膜にして対応する手法がとられている。そういった厚膜化を目的とするために設計された銀ナノ粒子として、特許文献３では、数nm～数十nm程度の一次粒子径を持った銀ナノ粒子を用いて、５～２０μｍの導電性銀塗膜が得られる銀塗料組成物（インク）が報告されている。また、特許文献４では、粒径１００～２００ｎｍの銀粒子を粒子数基準で３０％以上含むことにより焼結体とした際に低抵抗化できること、水分を銀化合物１００重量部に対して５～１００重量部反応系内に含ませることにより、そのような銀粒子を得ることができることが記載されている。 Although the use of a fired coating film using silver nanoparticles that can be fired at such low temperatures is expected as a conductive material such as wiring, in order to secure the reliability and conductivity as a conductive material such as wiring, wiring The corresponding method is taken to be a thick film. As silver nanoparticles designed for the purpose of making such a thick film, Patent Document 3 uses silver nanoparticles having a primary particle diameter of about several nm to several tens of nm, and provides conductivity of 5 to 20 μm. Silver coating compositions (inks) from which silver coatings can be obtained have been reported. Further, in Patent Document 4, by containing silver particles with a particle diameter of 100 to 200 nm by 30% or more based on the number of particles, resistance can be reduced when forming a sintered body, and water can be reduced to 5 to 100 parts by weight of silver compound. It is described that such silver particles can be obtained by being contained in a 100 parts by weight reaction system.
　これらの公知文献では、銀化合物とアミン化合物との錯体形成反応を利用して銀ナノ粒子を作成する。具体的にはシュウ酸銀とアルキルアミンまたはアルキルジアミンを無溶媒下で錯体形成を行う。しかし、無溶媒下で錯体形成すると、流動性がない固体物となり撹拌がしにくく、系の均一性に欠け、局所的に発熱反応を伴ったりするため、品質面・安全面に問題があり、工業的実用化が難しい。そこで、アルコール溶媒中で錯体形成反応を行うことで、錯体反応を促進・補助したり、系内の撹拌性を上げたり、熱分解で急激に発生する炭酸ガスを抑えたり、品質面・安全面を向上された銀ナノ粒子製造方法が報告されている（特許文献５～７）。 In these known documents, silver nanoparticles are formed using a complex formation reaction of a silver compound and an amine compound. Specifically, silver oxalate is complexed with an alkylamine or an alkyldiamine in the absence of a solvent. However, complex formation in the absence of a solvent results in a solid with no fluidity, which makes it difficult to agitate, lacks uniformity of the system, and locally causes exothermic reaction, resulting in problems in quality and safety, Industrial practical application is difficult. Therefore, by carrying out the complex formation reaction in an alcohol solvent, the complex reaction can be promoted or assisted, the stirring property in the system can be improved, the carbon dioxide gas generated rapidly by thermal decomposition can be suppressed, and the quality and safety A method of producing silver nanoparticles with an improved pH has been reported (Patent Documents 5 to 7).
　また、シュウ酸銀－アルキルアミン錯体を加熱分解する過程で、副生ガス（主に炭酸ガス）が発生して排出される際に、揮発しやすいアルキルアミンも含まれて系外に排出されてしまう問題を回避するため、前記錯体化合物を連続的に反応容器内に導入し、熱分解反応時の副生ガス発生量を制御した製造方法が報告されている（特許文献８）。 In the process of thermally decomposing the silver oxalate-alkylamine complex, when the by-product gas (mainly carbon dioxide gas) is generated and discharged, the easily volatilizable alkylamine is also contained and discharged out of the system. In order to avoid the problem, the production method is reported in which the complex compound is continuously introduced into the reaction vessel to control the amount of by-product gas generated during the thermal decomposition reaction (Patent Document 8).
特許第５５７４７６１号公報Patent No. 5574761 gazette 特開２０１２－１６２７６７号公報JP 2012-162767 A 特許第６００１８６１号公報Patent No. 6001861 gazette 特許第５７９５０９６号公報Patent No. 5795096 特許５９７５４４０号公報Patent 5975440 gazette 特許６０２６５６５号公報Patent No. 6026565 特開２０１６－１３２８２５号公報JP, 2016-132825, A 特開２０１５－４０３１９号公報JP, 2015-40319, A 特開２０１４－１５２３３７号公報JP 2014-152337 A
　しかし、特許文献３には、実施例では８μｍに達しない厚さの塗膜しか作成していない。仮に１０μｍ以上の導電性塗膜を作成したたとしても、銀粒子は一次粒子径が数１０ｎｍの粒子が主体なので、有機保護剤量も多く、保護剤離脱による体積収縮が生じるため、寸法安定性が低く、クラックによる断線の現象が起こる可能性が高い。 However, in the patent document 3, only the coating film of the thickness which does not reach 8 micrometers is produced in the Example. Even if a conductive coating film of 10 μm or more is formed, the silver particles are mainly particles having a primary particle diameter of several tens of nm, so the amount of the organic protective agent is large, and volumetric shrinkage occurs due to the removal of the protective agent. Is low, there is a high possibility of the occurrence of breakage due to cracks.
　また、特許文献５～８のように副生ガスの量を制御したとしても、最終的に系外へアルキルアミンを含んだ炭酸ガスを排出する事には変わりはない。 Further, even if the amount of by-product gas is controlled as in Patent Documents 5 to 8, the carbon dioxide gas containing an alkylamine is finally discharged out of the system.
　本発明は、以上の問題点を解決し、作業性・安全性・環境面等のスケールアップを考慮した銀ナノ粒子の製造方法、及び高分布の粒度分布範囲を持つ銀ナノ粒子の製造方法を提供することを課題とする。 The present invention solves the above problems and provides a method of producing silver nanoparticles in consideration of scale-up in workability, safety, environment, etc., and a method of producing silver nanoparticles having a particle size distribution range of high distribution. The task is to provide.
　これらの課題を解決するため、本発明者は鋭意検討を重ねた。その結果、銀化合物と錯体形成しうるアミン化合物として、エーテル結合を有する特定のアミノアルコールを使用することにより、アルキルアミンの排出が抑えられ、環境にやさしく、しかも同時に、得られる銀粒子は粒径と分布が優れたものであり、得られる焼結塗膜も優れた性能を有することを見出し、本発明に到達した。 The present inventors diligently studied to solve these problems. As a result, by using a specific amino alcohol having an ether bond as an amine compound capable of forming a complex with a silver compound, the emission of alkylamine is suppressed, and it is environmentally friendly, and at the same time, the silver particles obtained have a particle size It has been found that the obtained sintered coating film also has excellent performance, and reaches the present invention.
　すなわち、本発明には、以下の発明が含まれる。
（１）　熱分解性を有する銀化合物（ａ）と、（ａ）と錯体形成しうるアミン化合物（ｂ）とを有機溶媒（ｃ）中で反応させて錯体を形成し、得られた錯体を加熱して熱分解させることにより、銀ナノ粒子を形成する銀ナノ粒子の製造方法であって、（ｂ）が、直鎖状のアミノアルコールであり、その直鎖状分子の両末端にアミノ基と水酸基とを１つずつ持ち、直鎖状分子構造内に、エーテル結合を有するアミノアルコールであることを特徴とする銀ナノ粒子の製造方法。 That is, the present invention includes the following inventions.
(1) A thermally formed silver compound (a) and an amine compound (b) capable of forming a complex with (a) are reacted in an organic solvent (c) to form a complex, and the resulting complex is A method for producing silver nanoparticles forming silver nanoparticles by heating and thermal decomposition, wherein (b) is a linear amino alcohol, and amino groups at both ends of the linear molecule. It is an amino alcohol which has and one hydroxyl group and has an ether bond in a linear molecular structure, and the manufacturing method of the silver nanoparticle characterized by the above-mentioned.
（２）　（ｂ）が、炭素数４以上であることを特徴とする上記（１）記載の銀ナノ粒子の製造方法。
（３）　（ｂ）が、ジグリコールアミンである上記（１）又は（２）記載の銀ナノ粒子の製造方法。
（４）　（ａ）がシュウ酸銀である上記（１）～（３）のいずれかに記載の銀ナノ粒子の製造方法。
（５）　（ａ）と（ｂ）との錯体形成反応時に、銀化合物（ａ）１００重量部に対して５～２０重量部の水を存在させることを特徴とする上記（１）～（４）のいずれかに記載の銀ナノ粒子の製造方法。
（６）　（ｂ）／［（ａ）に含まれる銀原子］のモル比が０．７～２．０であることを特徴とする上記（５）記載の銀ナノ粒子の製造方法。
（７）　（ｃ）／（ａ）の重量比が０．８～１．３であることを特徴とする上記（１）～（６）のいずれかに記載の銀ナノ粒子の製造方法。 (2) The method for producing silver nanoparticles according to the above (1), wherein (b) has 4 or more carbon atoms.
(3) The method for producing silver nanoparticles according to the above (1) or (2), wherein (b) is diglycolamine.
(4) The method for producing silver nanoparticles according to any one of the above (1) to (3), wherein (a) is silver oxalate.
(5) In the complex formation reaction of (a) and (b), 5 to 20 parts by weight of water is present relative to 100 parts by weight of the silver compound (a). The manufacturing method of the silver nanoparticle in any one of these.
(6) The method for producing silver nanoparticles according to the above (5), wherein the molar ratio of (b) / [silver atom contained in (a)] is 0.7 to 2.0.
(7) The method for producing silver nanoparticles according to any one of the above (1) to (6), wherein the weight ratio of (c) / (a) is 0.8 to 1.3.
（８）　上記（１）～（７）のいずれかに記載の方法により銀ナノ粒子を作製し、得られた銀ナノ粒子を有機溶媒に分散することを特徴とする、銀ナノ粒子分散体の製造方法。
（９）　上記（１）～（８）のいずれかに記載の方法により銀ナノ粒子を作製し、得られた銀ナノ粒子を有機溶媒に分散し、さらに有機バインダーを添加することを特徴とする、銀塗料組成物の製造方法。
（１０）　上記（８）記載の方法により得られた銀ナノ粒子分散体又は上記（９）記載の方法により得られた銀塗料組成物を基板上に塗布し、焼成して銀導電層を形成する工程を含む銀導電材料の製造方法。 (8) A silver nanoparticle dispersion characterized in that silver nanoparticles are produced by the method according to any one of the above (1) to (7), and the obtained silver nanoparticles are dispersed in an organic solvent. Production method.
(9) A silver nanoparticle is produced by the method according to any one of the above (1) to (8), the obtained silver nanoparticle is dispersed in an organic solvent, and an organic binder is further added. , A method of producing a silver coating composition.
(10) The silver nanoparticle dispersion obtained by the method described in the above (8) or the silver coating composition obtained by the method described in the above (9) is coated on a substrate and fired to form a silver conductive layer A method of producing a silver conductive material comprising the steps of
　本発明に係る粒径制御された銀粒子を含む銀塗料組成物は、１５０℃以下の低温領域であっても焼結が可能で、生成する焼結体はバルクの銀に近い低抵抗値を示す。本発明は、スクリーン印刷を代表とする印刷方法により、ＰＥＴやポリプロピレンなどの比較的耐熱性の低いプラスチック基板上に、数～数１０μｍの厚膜の銀配線を成形できる材料、または導電性の接合材料やパワーデバイス等の大電流を取り扱う電気機器の接合材として利用が期待できる。 The silver coating composition containing silver particles with controlled particle size according to the present invention can be sintered even in a low temperature range of 150 ° C. or lower, and the sintered body produced has a low resistance value close to that of bulk silver. Show. The present invention is a material capable of forming a silver wiring having a thickness of several to several tens of μm on a relatively low heat resistant plastic substrate such as PET or polypropylene by a printing method typified by screen printing, or conductive bonding. It can be expected to be used as a bonding material for electrical devices that handle large currents such as materials and power devices.
　また、本発明での銀粒子の合成では、使用するアミン化合物量が従来の合成法よりも少ない他、熱分解性を持つ銀化合物と錯形成を起こすアミン化合物として、特定の炭素数４以下のアミノアルコールを用いることにより、人体や環境の負荷の高いアルキルアミンの利用をさらに低減できるので、スケールアップされた工業的な製造において、安全性の高い製造方法が提供される。 In addition, in the synthesis of silver particles in the present invention, the amount of amine compound used is smaller than that of the conventional synthesis method, and an amine compound which forms a complex with a thermally decomposable silver compound has a specific carbon number of 4 or less The use of amino alcohol can further reduce the use of alkylamines with high human and environmental loads, thereby providing a highly safe production method in scaled up industrial production.
図１は、アミン化合物の銀原子への配位モデル及び成長イメージを示すイメージ図である。　図１中、図１－１は、ジグリコールアミンの銀原子への配位モデル（直鎖型）、図１－２は、ジグリコールアミンの銀原子への配位モデル（ＯＨ基接近型）、図１－３は、アルキルアミンの銀原子への配位モデルのイメージ図である。　図１－４は、アルキルアミンに多い直鎖型吸着と銀粒子成長のイメージを示すイメージ図、図１－５は、アミノアルコールのＯ原子吸着型吸着と銀粒子成長のイメージを示すイメージ図、図１－６は、アミノアルコールの現実的な吸着と銀粒子成長イメージを示すイメージ図である。FIG. 1 is an image diagram showing a coordination model of an amine compound to a silver atom and a growth image. In FIG. 1, FIG. 1-1 is a coordination model (straight chain type) of diglycolamine to a silver atom, and FIG. 1-2 is a coordination model of diglycolamine to a silver atom (OH group approach type). FIGS. 1-3 are images of coordination models of alkylamines to silver atoms. Fig. 1-4 is an image showing the image of linear adsorption and silver particle growth that is rich in alkylamine, Fig. 1-5 is an image showing the image of O atom adsorption type adsorption of amino alcohol and silver particle growth, Fig. 1 6 is an image showing a realistic adsorption of amino alcohol and a silver particle growth image. 図２は、実施例１で得られた粒子のＳＥＭ写真を示す図である。FIG. 2 is a view showing a SEM photograph of particles obtained in Example 1. 図３は、実施例２で得られた粒子のＳＥＭ写真を示す図である。FIG. 3 is a view showing a SEM photograph of particles obtained in Example 2. 図４は、実施例３で得られた粒子のＳＥＭ写真を示す図である。FIG. 4 is a view showing a SEM photograph of particles obtained in Example 3. 図５は、実施例４で得られた粒子のＳＥＭ写真を示す図である。FIG. 5 is a view showing a SEM photograph of particles obtained in Example 4. 図６は、実施例５で得られた粒子のＳＥＭ写真を示す図である。FIG. 6 is a view showing a SEM photograph of particles obtained in Example 5. 図７は、実施例６で得られた粒子のＳＥＭ写真を示す図である。FIG. 7 is a view showing a SEM photograph of particles obtained in Example 6. 図８は、実施例７で得られた粒子のＳＥＭ写真を示す図である。FIG. 8 is a view showing a SEM photograph of the particles obtained in Example 7. 図９は、実施例８で得られた粒子のＳＥＭ写真を示す図である。FIG. 9 is a view showing a SEM photograph of particles obtained in Example 8. 図１０は、比較例１で得られた粒子のＳＥＭ写真を示す図である。FIG. 10 is a view showing a SEM photograph of particles obtained in Comparative Example 1. 図１１は、比較例２、３で得られた粒子のＳＴＥＭ写真を示す図である。FIG. 11 is a view showing STEM photographs of particles obtained in Comparative Examples 2 and 3. 図１２は、比較例４で得られた粒子のＳＴＥＭ写真を示す図である。FIG. 12 is a view showing a STEM photograph of particles obtained in Comparative Example 4. 図１３は、比較例５で得られた粒子のＳＥＭ写真を示す図である。FIG. 13 is a view showing a SEM photograph of the particles obtained in Comparative Example 5. 図１４は、比較例６で得られた粒子のＳＥＭ写真を示す図である。FIG. 14 is a view showing a SEM photograph of particles obtained in Comparative Example 6. 図１５は、比較例７で得られた粒子のＳＥＭ写真を示す図である。FIG. 15 is a view showing a SEM photograph of particles obtained in Comparative Example 7. 図１６は、比較例８で得られた粒子のＳＥＭ写真を示す図である。FIG. 16 is a view showing a SEM photograph of particles obtained in Comparative Example 8. 図１７は、比較例９で得られた粒子のＳＥＭ写真を示す図である。FIG. 17 is a view showing a SEM photograph of particles obtained in Comparative Example 9. 図１８は、比較例１０で得られた粒子のＳＥＭ写真を示す図である。FIG. 18 is a view showing a SEM photograph of particles obtained in Comparative Example 10. 図１９は、比較例１１で得られた粒子のＳＥＭ写真を示す図である。FIG. 19 is a view showing a SEM photograph of particles obtained in Comparative Example 11. 図２０は、比較例１２で得られた粒子のＳＥＭ写真を示す図である。FIG. 20 is a view showing a SEM photograph of the particles obtained in Comparative Example 12. 図２１は、実施例１で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 21 is a diagram showing a particle size distribution histogram of particles obtained in Example 1. 図２２は、実施例２で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 22 is a diagram showing a particle size distribution histogram of particles obtained in Example 2. 図２３は、実施例３で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 23 is a diagram showing a particle size distribution histogram of particles obtained in Example 3. 図２４は、実施例４で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 24 is a diagram showing a particle size distribution histogram of particles obtained in Example 4. 図２５は、実施例５で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 25 is a diagram showing a particle size distribution histogram of particles obtained in Example 5. 図２６は、実施例６で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 26 is a diagram showing a particle size distribution histogram of particles obtained in Example 6. 図２７は、実施例７で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 27 is a diagram showing a particle size distribution histogram of particles obtained in Example 7. 図２８は、実施例８で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 28 is a diagram showing a particle size distribution histogram of particles obtained in Example 8. 図２９は、比較例１で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 29 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Example 1. 図３０は、比較例２、３で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 30 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Examples 2 and 3. 図３１は、比較例４で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 31 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Example 4. 図３２は、比較例１１で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 32 is a graph showing a particle size distribution histogram of particles obtained in Comparative Example 11. 図３３は、比較例１２で得られた粒子の粒度分布ヒストグラムを示す図である。FIG. 33 is a diagram showing a particle size distribution histogram of particles obtained in Comparative Example 12.
　本発明は、熱分解性を有する銀化合物（ａ）と錯体形成するアミン化合物（ｂ）を反応させて銀ナノ粒子を製造する方法において、アミン化合物として、(i)直鎖状構造であって、(ii)アミノ基と水酸基が直鎖状分子の量末端に１つずつ持ち、かつ(iii)直鎖状構造内にエーテル結合を１つ以上有するアミノアルコールを使用することが特徴である。このような特定のアミノアルコールを使用することにより、広分布で比較的大粒径の銀ナノ粒子を容易に得ることができ、特に２００～５００ｎｍの大粒径領域の銀ナノ粒子を合成しやすく、またアミン化合物全体の使用量を少なくすることができるため環境に優れている。
　以下、詳細に説明する。 The present invention relates to a method for producing silver nanoparticles by reacting an amine compound (b) complexed with a thermally decomposable silver compound (a) to produce a silver nanoparticle, wherein the amine compound has (i) a linear structure It is characterized in that (ii) an amino alcohol having one amino group and one hydroxyl group at one end of the linear molecule and (iii) one or more ether bonds in the linear structure. By using such a specific amino alcohol, silver nanoparticles having a wide distribution and relatively large particle size can be easily obtained, and in particular, it is easy to synthesize silver nanoparticles in a large particle size range of 200 to 500 nm. Also, it is excellent in environment because the amount of use of the entire amine compound can be reduced.
The details will be described below.
＜銀ナノ粒子合成における材料の説明＞
〔１．銀化合物（ａ）の説明〕
　本発明の銀粒子の製造方法では、まず、出発原料として熱分解性を有する銀化合物を用いる。熱分解性を有する銀化合物とは、後述する成分（ｂ）と錯体化して、通常の設備で可能な加熱条件下で熱分解する銀化合物をいう。具体的には、シュウ酸銀、硝酸銀、酢酸銀、炭酸銀、酸化銀、亜硝酸銀、安息香酸銀、シアン酸銀、クエン酸銀、乳酸銀等を適応できる。これら銀化合物のうち、特に好ましいのは、炭酸銀又はシュウ酸銀（Ａｇ２Ｃ２Ｏ４）である。さらに好ましくはシュウ酸銀である。シュウ酸銀は、還元剤を要することなく比較的低温で分解して銀粒子を生成することができる。また、分解により生じる二酸化炭素はガスとして放出されることから、溶液中に不純物を残留させることもないためである。 <Explanation of materials in silver nanoparticle synthesis>
[1. Description of silver compound (a)]
In the method for producing silver particles of the present invention, first, a thermally decomposable silver compound is used as a starting material. The thermally decomposable silver compound refers to a silver compound which is complexed with the component (b) described later and thermally decomposed under heating conditions which are possible with ordinary equipment. Specifically, silver oxalate, silver nitrate, silver acetate, silver carbonate, silver oxide, silver nitrite, silver benzoate, silver cyanate, silver citrate, silver lactate and the like can be applied. Among these silver compounds, silver carbonate or silver oxalate (Ag 2 C 2 O 4 ) is particularly preferable. More preferably, it is silver oxalate. Silver oxalate can be decomposed at relatively low temperatures without the need for a reducing agent to produce silver particles. In addition, carbon dioxide generated by the decomposition is released as a gas, so that no impurities are left in the solution.
〔２．錯体形成するアミン化合物（ｂ）〕
　次に、本発明においては、（ｂ）成分として銀化合物と錯体形成しうるアミン化合物を用いる。この化合物は、銀化合物と錯体を形成して銀化合物の熱分解温度を下げ、低温で銀粒子を生成することを可能にする機能を有する。同時に、アミン化合物の有する有機基により、銀粒子の分散安定性の効果を持たせる保護剤の機能を有する。このようなアミン化合物としては、銀化合物と錯体を形成しうるアミン化合物であれば特に限定されない。特に、アミン化合物のアミノ基に結合する水素原子の数は、１つまたは２つ、すなわち、１級アミン（RNH2）、又は２級アミン（R2NH）が好ましい。 [2. Amine Compound Complexed (b)]
Next, in the present invention, an amine compound capable of forming a complex with a silver compound is used as the component (b). This compound has the function of forming a complex with the silver compound to lower the thermal decomposition temperature of the silver compound and enabling silver particles to be formed at a low temperature. At the same time, the organic group possessed by the amine compound has the function of a protective agent to have the effect of the dispersion stability of silver particles. Such an amine compound is not particularly limited as long as it is an amine compound that can form a complex with a silver compound. In particular, the number of hydrogen atoms bonded to the amino group of the amine compound is preferably one or two, that is, a primary amine (RNH 2 ) or a secondary amine (R 2 NH).
　このように銀化合物と、これと錯体形成しうるアミン化合物から銀粒子を形成すること自体は背景技術として説明したように公知である。そして本発明でも、アミン化合物として公知技術で使用されてきた「脂肪族炭化水素モノアミン」や「脂肪族炭化水素ジアミン」のような脂肪族炭化水素アミン化合物を使用することも差し支えない。「脂肪族炭化水素モノアミン」や「脂肪族炭化水素ジアミン」として具体的には、アルキルアミン、アルコキシアミン、アルキルエーテルアミンが挙げられる。このうちアルキルアミンとしては、ｎ－ブチルアミン、ｎ－ペンチルアミン、ｎ－ヘキシルアミン、ｎ－ヘプチルアミン、ｎ－オクチルアミン、２－エチルヘキシルアミン等が挙げられる。 Such formation of silver particles from a silver compound and an amine compound that can be complexed with the silver compound is known as described in the background art. Also in the present invention, it is also acceptable to use aliphatic hydrocarbon amine compounds such as "aliphatic hydrocarbon monoamines" and "aliphatic hydrocarbon diamines" which have been used as amine compounds in the known art. Specifically as "aliphatic hydrocarbon monoamine" or "aliphatic hydrocarbon diamine", alkylamine, alkoxyamine, alkyl ether amine is mentioned. Among these, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine and the like can be mentioned as the alkylamine.
　しかし、これらのアミン化合物のうちアルキルアミンは刺激臭が強く、分解反応時に炭酸ガスとともに高温で排出されるリスクがあるので、刺激臭を抑えたい場合には、酸素原子を含むアミン化合物を用いるのが好ましい。具体的には、アルコキシアミン、アルキルエーテルアミン、アミノアルコールである。
　本発明者の検討により、これらの酸素原子を含むアミン化合物は、刺激臭が抑えられるだけでなく、そのうち特に以下に説明する特定のアミノアルコールは、得られる銀粒子の物性も優れていることが判明した。 However, among these amine compounds, alkylamine has a strong irritating odor, and there is a risk of being discharged at high temperature together with carbon dioxide gas during the decomposition reaction. Therefore, when it is desired to suppress the irritating odor, use an amine compound containing an oxygen atom. Is preferred. Specifically, they are alkoxyamines, alkyl ether amines, and amino alcohols.
According to the study of the present inventor, the amine compound containing these oxygen atoms not only can suppress the irritating odor but, among them, the specific amino alcohol described below in particular has excellent physical properties of the obtained silver particles. found.
［２－１．大粒子径・広分布効果のあるアミノアルコール（ｂ１）］
　次に、本発明においては、（ｂ）成分である銀化合物と錯体形成しうるアミン化合物として、以下のものを使用することを特徴とする。すなわち、(i)直鎖状構造であって、(ii)アミノ基と水酸基が直鎖状分子の量末端に１つずつ持ち、かつ(iii)直鎖状構造内にエーテル結合を１つ以上有するアミノアルコール（ｂ１）を使用することが特徴である。これらのアミン化合物は、銀化合物と錯体を形成することにより、銀化合物の熱分解温度を下げ、低温で銀粒子を生成することを可能にする機能を有する。さらに、本発明においては、得られる銀粒子の粒径を容易に大きくかつ広い分布のものとすることを可能にする。すなわち、上記の（ｂ）成分を使用することにより、意外にも、得られる銀ナノ粒子は、粒径が比較的大きく、しかも粒度分布が広いものであることが本発明者らの検討により判明したのである。この大粒径で分布が広い銀ナノ粒子は、後述するように、優れた効果を有するものである。 [2-1. Amino alcohol with large particle size and wide distribution effect (b1)]
Next, the present invention is characterized by using the following as an amine compound which can be complexed with the silver compound which is the component (b). That is, (i) a linear structure, and (ii) one amino group and one hydroxyl group at each end of the linear molecule, and (iii) one or more ether bonds in the linear structure It is characterized by using the amino alcohol (b1) which it has. These amine compounds have the function of lowering the thermal decomposition temperature of the silver compound and forming silver particles at a low temperature by forming a complex with the silver compound. Furthermore, in the present invention, it is possible to easily make the obtained silver particles have a large and wide distribution. That is, by using the above-mentioned component (b), it is unexpectedly found that the obtained silver nanoparticles have a relatively large particle size and a broad particle size distribution. It is The silver nanoparticles having a large particle size and a wide distribution have excellent effects as described later.
　アミン化合物（ｂ１）のアミノ基の級数は限定されず、１級アミン、２級アミン又は３級アミンのいずれも使用できるが、特に１級又は２級が錯体を形成しやすいので好ましい。
　このアミン化合物（ｂ１）は、(i)直鎖状構造を有する。ここで「直鎖状」とは、アミン化合物を構成する炭素原子とヘテロ原子とが、直鎖状につながっていて分岐を有さないことをいう。この炭素原子とヘテロ原子の直鎖状構造の両末端にそれぞれ、(ii)アミノ基と水酸基とを有している。そして直鎖状構造内に(iii)１つ以上のエーテル結合を有している。エーテル結合の数は１つ以上であれば限定されない。
　これら(i)～(iii)の特徴を有することにより、後述するメカニズムにより上述した優れた効果が得られていると考えられる。 The series number of the amino group of the amine compound (b1) is not limited, and any of primary amines, secondary amines or tertiary amines can be used, but in particular, primary or secondary ones are preferable because they tend to form a complex.
The amine compound (b1) has (i) a linear structure. Here, “linear” means that a carbon atom constituting an amine compound and a hetero atom are linearly connected and have no branch. It has an amino group and a hydroxyl group respectively at both ends of the linear structure of the carbon atom and the hetero atom. And (iii) have one or more ether bonds in the linear structure. The number of ether bonds is not limited as long as it is one or more.
By having the features (i) to (iii), it is considered that the above-described excellent effect is obtained by the mechanism described later.
　（ｂ１）成分のアミノアルコールの炭素数は限定されないが、　炭素数４以上が好ましい。通常、炭素数４～７である。この範囲で前述した優れた効果が最も優れている。すなわち、得られる銀粒子の粒径が大きくかつ粒度分布が広くなる。おそらく、炭素数４以上の場合に、後述するメカニズムにおける２つの配位結合モデル間の、立体障害における排除体積の差が大きくなるため、粒子が大きく成長し、かつ粒度分布が広くなると推測される。 The carbon number of the amino alcohol of the component (b1) is not limited, but is preferably 4 or more. Usually, it has 4 to 7 carbon atoms. The above-mentioned excellent effects are the best in this range. That is, the particle size of the obtained silver particles is large and the particle size distribution is broad. Presumably, when the number of carbon atoms is 4 or more, the difference in excluded volume in steric hindrance between the two coordination models in the mechanism described later becomes large, so it is speculated that the particles grow large and the particle size distribution becomes broad. .
　以上の条件を満たすアミノアルコールとしては、例えば、ジグリコールアミン、３－（３－アミノプロポキシ）プロパノール、２－［２－（３-アミノプロポキシ）エトキシ]エタノールが挙げられる。好ましくは、ジグリコールアミンである。従来の脂肪族炭化水素アミン化合物のような強い刺激臭もなく、取り扱う上でも安全面で有利である。なお、以上の（ｂ１）成分は、１種のみを用いても、２種以上混合して用いてもよい。 Examples of the amino alcohol satisfying the above conditions include diglycolamine, 3- (3-aminopropoxy) propanol and 2- [2- (3-aminopropoxy) ethoxy] ethanol. Preferably, it is diglycolamine. There is no strong smell like the conventional aliphatic hydrocarbon amine compounds, and it is advantageous in terms of safety in handling. The above component (b1) may be used alone or in combination of two or more.
［２－１．（ｂ１）成分添加による大粒子径銀粒子生成メカニズム］
　以上説明した（ｂ１）成分を銀化合物と錯体形成するアミン化合物を用いることにより、大粒径で分布の広い銀ナノ粒子を得ることのできるメカニズムは完全には明らかではない。しかし、本発明者は以下のように推測している。
　アミン化合物と銀化合物の錯体形成は、アミン化合物のアミノ基の非共有電子対が、銀原子の空軌道に配位して形成される。アミン化合物中の水酸基についても、アミノ基と同様に極性がありマイナスに帯電していることから、銀原子へ接近しやすい挙動を示すと考えられる。この性質を踏まえ、（ｂ１）成分である特定のアミノアルコールの銀原子の配位結合状態について、以下のモデルが考えられる。i)アミノ基が銀原子へ配位し、アルキル鎖が外側（分散媒側）へ直線状に配向するモデル（図１－１）、ii)アミノ基が銀原子へ配位し、水酸基や構造中のエーテル結合部分の酸素原子も銀原子側へ近づき安定化するモデル（図１－２）である。この２つの配位結合モデルが存在するために、銀原子周辺でのアミン化合物による立体障害が一様ではない。このため、出来上がる粒子径にバラつきが生まれ、大粒子径から小粒子径まで幅広く形成されると考えられる。 [2-1. Formation mechanism of large particle size silver particles by the addition of the component (b1)]
The mechanism by which silver nanoparticles having a large particle size and a wide distribution can be obtained is not completely clear by using an amine compound which complexes the component (b1) with the silver compound described above. However, the inventor speculates as follows.
The complex formation of an amine compound and a silver compound is formed by coordinating the noncovalent electron pair of the amino group of the amine compound to the empty orbital of the silver atom. The hydroxyl group in the amine compound is also polar and negatively charged in the same manner as the amino group, and therefore, is considered to exhibit a behavior that allows easy access to the silver atom. Based on this property, the following model is considered about the coordination state of the silver atom of the specific amino alcohol which is (b1) component. i) A model in which an amino group is coordinated to a silver atom and an alkyl chain is linearly oriented to the outside (dispersion medium side) (Fig. 1-1), ii) An amino group is coordinated to a silver atom, hydroxyl group or structure The oxygen atom in the ether bond in the model is also a model that approaches and stabilizes on the silver atom side (Fig. 1-2). Due to the existence of these two coordination models, the steric hindrance by the amine compound around the silver atom is not uniform. For this reason, it is thought that dispersion occurs in the particle diameter to be produced, and the particle diameter is formed widely from large particle diameter to small particle diameter.
　これに対し、従来用いられてきたアルキルアミンについては、アミノ基部分しか電子供与性がないので、直線状にしか配向しないので、図１－３のようになる。したがって、粒子のばらつきは生まれにくい。粒子の揃った銀粒子しか合成できないのはこのためであると考えられる。 On the other hand, alkylamines that have been used in the prior art are only linearly oriented since only the amino group has electron donating properties, as shown in FIG. 1-3. Therefore, the variation of particles is hard to occur. This is considered to be the reason why only silver particles with uniform particles can be synthesized.
〔３．錯形成を促進させるアミノアルコール（ｂ２）〕
　本発明では、（ｂ１）成分と併用して、酸素原子を含むアミン化合物、特に炭素数３～４のアミノアルコール（ｂ２）を用いることができる。（ｂ２）成分は、粒子径を大きく、かつ粒度分布を広くする効果を一層上げることができるので好ましい。
　さらに好ましくは、（i）炭素数３～４の分岐型1級アミノアルコールであって、(ii)アミノ基と水酸基とを１つずつ持ち、かつ(iii)炭素数２のアルキル鎖を介して、アミノ基と水酸基が結合されているもの、またはiv)炭素数３の直鎖状２級アミノアルコールである。このような特定のアミノアルコールを用いることにより、特に得られる銀粒子の粒径を容易に大きくかつ広い分布のものとすることを可能にする。
　ここで、(i)「分岐型」とは、炭素原子とヘテロ原子とからなる骨格が直線状ではなく枝分かれしていることをいう。また(ii)アミノ基と水酸基とを１つずつ持つものであれば、その数は限定されないが、通常は各々１つずつが好ましい。(iii)「炭素数２のアルキル鎖を介して、アミノ基と水酸基が結合されている」とは、炭素原子とヘテロ原子とからなる骨格中、隣り合った２つの炭素原子に各々、アミノ基と水酸基とが結合していることをいう。
　この条件を満たすアミノアルコール（ｂ２）を併用することにより、アミン化合物（ｂ１）のみを使用した場合と比べて、銀化合物との錯体反応をより促進させることができ、かつ一層大粒径で分布の広い粒子を得ることができる。 [3. Amino alcohol which promotes complex formation (b2)]
In the present invention, an amine compound containing an oxygen atom, particularly an amino alcohol having 3 to 4 carbon atoms (b2) can be used in combination with the component (b1). The component (b2) is preferable because the effect of increasing the particle diameter and broadening the particle size distribution can be further enhanced.
More preferably, it is (i) a branched primary amino alcohol having 3 to 4 carbon atoms, (ii) having one amino group and one hydroxyl group, and (iii) via an alkyl chain having 2 carbon atoms. An amino group and a hydroxyl group, or iv) a linear secondary amino alcohol having 3 carbon atoms. The use of such specific amino alcohols makes it possible, in particular, to make the particle size of the silver particles obtained easily of large and broad distribution.
Here, (i) "branched" means that a skeleton composed of carbon atoms and hetero atoms is not linear but branched. The number is not limited as long as it has (ii) one amino group and one hydroxyl group, but in general, one each is preferable. (iii) “The amino group and the hydroxyl group are bonded via an alkyl chain having 2 carbon atoms” means that two adjacent carbon atoms in the skeleton consisting of carbon atoms and hetero atoms each have an amino group. And the hydroxyl group are bound.
The combined use of the amino alcohol (b2) satisfying the above conditions can accelerate the complex reaction with the silver compound as compared with the case where only the amine compound (b1) is used, and distribution with a larger particle size It is possible to obtain wide particles of
　以上の条件を満たす炭素数４以下のアミノアルコールとしては、(i)～(iii)を満たすアミノアルコールとして、１－アミノ－２－ブタノール、ＤＬ－１－アミノ－２－プロパノール、２－アミノ－２－メチル－１－プロパノール（以下、ＡＭＰ）、ＤＬ－２－アミノ－１－プロパノール、が挙げられる。また、(iv)を満たすアミノアルコールとして、Ｎ－メチルエタノールアミン、が挙げられる。 Examples of amino alcohols having 4 or less carbon atoms which satisfy the above conditions include 1-amino-2-butanol, DL-1-amino-2-propanol, 2-amino-, and the like as amino alcohols satisfying (i) to (iii). Examples include 2-methyl-1-propanol (hereinafter AMP) and DL-2-amino-1-propanol. Moreover, N-methyl ethanolamine is mentioned as an amino alcohol which satisfy | fills (iv).
　これらのうち特に、(i)～(iii)を満たすアミノアルコールであるＡＭＰ、１－アミノ－２－ブタノール、ＤＬ－１－アミノ－２－プロパノール、及びＤＬ－２－アミノ－１－プロパノールがが扱いやすく、アルコール溶媒のような極性溶媒存在下での錯形成が容易に起こり、かつ大粒径かつ広い粒度分布の銀粒子を容易に得ることができるので最も好ましい。これらのうちでも特に、ＡＭＰが最も以上の効果が高く優れている。
　なお、以上の（ｂ２）成分は、１種のみを用いても、２種以上混合して用いてもよい。 Among these, AMP, which is an amino alcohol satisfying (i) to (iii), 1-amino-2-butanol, DL-1-amino-2-propanol, and DL-2-amino-1-propanol are particularly preferred. It is most preferred as it is easy to handle, complex formation in the presence of polar solvents such as alcohol solvents occurs easily, and silver particles of large particle size and wide particle size distribution can be easily obtained. Among these, AMP is the most effective and superior.
The above component (b2) may be used alone or in combination of two or more.
〔４．立体障害による分散安定化効果を持つアミン化合物（ｂ３）〕
　本発明ではさらに、（ａ）と（ｂ）の錯体形成時に、以上説明した（ｂ１）（ｂ２）成分以外のアミン化合物を存在させることができる。
　この成分は、立体障害効果により、銀粒子の分散安定性の効果を持たせる機能を有する。
　（ｂ１）（ｂ２）成分以外のアミン化合物として、特に分子の長さが５Å以上のものが好ましい。すなわち、分子の長さが５Å以上であって、前述した（ｂ１）及び（ｂ２）の各要件にあてはまらないアミン化合物である。
　ここで、分子の長さとは、水素原子を含まない最も距離の長い２原子の距離である。この分子の長さは計算により求めることができる。計算条件は、密度汎関数法、関数　ωB97X-D、基底関数　6-31＋G*、環境　真空中 　エネルギー状態　基底状態、で、SPARTAN`16V1,1,0 など各種の分子計算ソフトウェアで計算できる。
　分子の長さは好ましくは７Å以上である。もっとも、あまり長いと沸点が高くなり、除去することが難しくなるので、好ましくは、８Å以下である。 [4. Amine compound (b3) having a dispersion stabilization effect by steric hindrance
In the present invention, at the time of the complex formation of (a) and (b), an amine compound other than the components (b1) and (b2) described above can be present.
This component has a function of imparting the dispersion stability effect of silver particles by the steric hindrance effect.
As the amine compounds other than the components (b1) and (b2), those having a molecular length of 5 Å or more are particularly preferable. That is, it is an amine compound which has a molecule length of 5 Å or more and does not meet the requirements of (b1) and (b2) described above.
Here, the length of the molecule is the distance of the longest two atoms that do not contain hydrogen atoms. The length of this molecule can be determined by calculation. The calculation conditions are density functional theory, function ωB97X-D, basis function 6-31 + G *, environment in vacuum energy state, ground state, and can be calculated with various molecular calculation software such as SPARTAN `16V 1, 1, 0.
The length of the molecule is preferably 7 Å or more. However, if the length is too long, the boiling point becomes high and removal becomes difficult, so the thickness is preferably 8 Å or less.
　特に、アミノ基を含めて７原子以上で構成された主鎖（主骨格）を持つアミン化合物が好ましい。
　中でも、アミン化合物を構成する原子が、Ｎ、Ｃ及びＨであるもの、又はＮ、Ｃ、Ｈ及びＯであるものが好ましい。
　アミン化合物のアミノ基に結合する炭化水素基の数は限定されないが、１つまたは２つである１級アミン又は２級アミンが特に銀と配位結合しやすいので好ましい。
　このような（ｂ３）成分としては、例えば炭素総数４以上の脂肪族炭化水素モノアミンが挙げられる。 In particular, amine compounds having a main chain (main skeleton) composed of 7 atoms or more including amino groups are preferable.
Among them, those in which the atoms constituting the amine compound are N, C and H or those in which N, C, H and O are preferable.
The number of hydrocarbon groups bonded to the amino group of the amine compound is not limited, but one or two primary amines or secondary amines are preferred because they are particularly susceptible to coordinate bonding with silver.
Examples of such component (b3) include aliphatic hydrocarbon monoamines having 4 or more carbons in total.
　炭素数４以上の脂肪族炭化水素モノアミンは、従来技術で説明した銀化合物と錯体を形成して銀ナノ粒子を形成する方法で多く用いられているものである。しかし、炭素数４以上の脂肪族炭化水素モノアミンは、刺激臭が強く、分解反応時に炭酸ガスと共に高温で排出されるリスクがあるので、他のアミン化合物を用いても良い。具体的には、炭素数４以上の、酸素原子を含むアミン化合物（アルコキシアミン、アルキルエーテルアミン、アミノアルコール）であって、（ｂ２）成分として前述した(i)～(iii)又は(iv)にあたらないものである。 The aliphatic hydrocarbon monoamine having 4 or more carbon atoms is often used in the method of forming a complex with the silver compound described in the prior art to form silver nanoparticles. However, since aliphatic hydrocarbon monoamines having 4 or more carbon atoms have a strong irritating odor and there is a risk of being discharged together with carbon dioxide gas at the time of decomposition reaction, other amine compounds may be used. Specifically, it is an amine compound (alkoxyamine, alkyl ether amine, amino alcohol) containing an oxygen atom and having 4 or more carbon atoms, and (i) to (iii) or (iv) described above as the component (b2) It is something that does not affect.
　以上の（ｂ３）成分の具体例として、アルキルアミンとしては、ｎ－ブチルアミン、ｎ－ペンチルアミン、ｎ－ヘキシルアミン、ｎ－ヘプチルアミン、ｎ－オクチルアミン、２－エチルヘキシルアミン等が挙げられる。アルコキシアミンとしては、３－メトキシプロピルアミン、３－エトキシプロピルアミン等が挙げられる。アルキルエーテルアミンとしては、ＨＵＮＴＳＭＡＮ製ＪＥＦＦＡＭＩＮＥのＭシリーズ、Ｍ－６００、Ｍ－１０００、Ｍ－２００５、Ｍ－２０７０等が挙げられる。アミノアルコールとしては、４－アミノ－１－ブタノール、５－アミノ－１－ペンタノール、６－アミノ－１－ヘキサノール等が挙げられる。 Specific examples of the above component (b3) include n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine and the like as the alkylamine. As the alkoxyamine, 3-methoxypropylamine, 3-ethoxypropylamine and the like can be mentioned. Examples of the alkyl ether amines include M series of JEFFAMINE manufactured by HUNTSMAN, M-600, M-1000, M-2005, M-2070 and the like. Examples of the amino alcohol include 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol and the like.
　より好適な具体例としては、アルキルアミンとしては、ｎ－ペンチルアミン、ｎ－ヘキシルアミン、ｎ－ヘプチルアミン、ｎ－オクチルアミン、２－エチルヘキシルアミン等が挙げられる。アルコキシアミンとしては、３－メトキシプロピルアミン、３－エトキシプロピルアミン等が挙げられる。アミノアルコールとしては、５－アミノ－１－ペンタノール、６－アミノ－１－ヘキサノール等が挙げられる。
以上の（ｂ３）成分は、１種類もしくは２種類以上併用しても可能である。 More preferable examples of the alkylamine include n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine and the like. As the alkoxyamine, 3-methoxypropylamine, 3-ethoxypropylamine and the like can be mentioned. Examples of amino alcohols include 5-amino-1-pentanol, 6-amino-1-hexanol and the like.
The above component (b3) may be used alone or in combination of two or more.
（３－１．アミン化合物内でのモル比率　（ｂ２）／（ｂ））
　（ｂ２）／（ｂ）は、好ましくは０．３～０．８（モル比）、好ましくは０．４～０．８である。この範囲は、大粒子で高分布を持つ銀ナノ粒子を製造するのに、最も適している。前記モル比率が、０．３よりも小さくなると、分子の長さが長いアミン化合物の添加量が多くなり、粒子が全体に小さくなり、粒度分布も狭くなる傾向があり好ましくない。また、前記モル比率が０．８より大きくなると、保護剤としての立体障害効果が弱くなり、合成時に銀粒子の融着が起こるリスクが高くなる。 (3-1. Molar ratio in amine compound (b2) / (b))
(B2) / (b) is preferably 0.3 to 0.8 (molar ratio), preferably 0.4 to 0.8. This range is most suitable for producing large sized, high distribution silver nanoparticles. When the molar ratio is smaller than 0.3, the amount of addition of the amine compound having a long molecule length increases, the particles become small overall, and the particle size distribution tends to be narrow, which is not preferable. In addition, when the molar ratio is larger than 0.8, the steric hindrance effect as the protective agent is weakened, and the risk that the silver particles are fused at the time of synthesis is increased.
（３－２．アミン化合物（ｂ）とシュウ酸銀（ａ）の比率・添加量について）
　銀化合物の銀原子とアミン化合物（ｂ）との混合量について、そのモル比（アミン化合物／銀化合物の銀原子）が、０．７～２．０ となるようにしてアミン化合物（ｂ）の量を調整するのが望ましい。そうすることにより、粒径にばらつきが生まれ、目的の粒径範囲の銀粒子を得ることが容易である。より好ましくは０．７～１．５、さらに好ましくは０．７～１．３もっとも好ましくは０．７～１．３である。 (3-2. Regarding the ratio and addition amount of amine compound (b) and silver oxalate (a))
With regard to the mixing amount of the silver atom of the silver compound and the amine compound (b), the molar ratio (amine compound / silver atom of the silver compound) is 0.7 to 2.0 so that the amine compound (b) It is desirable to adjust the amount. By doing so, variations in particle size occur, and it is easy to obtain silver particles in the target particle size range. More preferably, it is 0.7 to 1.5, still more preferably 0.7 to 1.3, and most preferably 0.7 to 1.3.
　前述した従来の各種の合成方法（特許文献１～８）においては、アミン化合物／銀化合物の銀原子のモル比が２．０以上である。これに対して本発明では、より少ないアミン量で銀粒子を得ることができるので、アミン排出量も少なくて済む。したがって、アミンの系外放出による人体や環境負荷のリスクを軽減できる。また同時に、このような従来の方法では、粒子径も小さく、分布の狭い粒子が合成されやすくなってしまうのに対し、本発明においては、分布が広く大粒径の銀粒子を得ることができ、最終的に低温焼結性に優れ、低抵抗な厚膜導電焼結体が得ることができるのである。
　他方、モル比が０．７を下回ると、扁平状の粒子ができやすく凝集しやすいため、銀塗料組成物の分散安定性が低くなる。 In the above-described various conventional synthetic methods (Patent Documents 1 to 8), the molar ratio of silver atoms in the amine compound / silver compound is 2.0 or more. On the other hand, in the present invention, since silver particles can be obtained with a smaller amount of amine, the amount of amine discharge can also be small. Therefore, it is possible to reduce the risk of human body and environmental load due to the release of amine from the system. At the same time, such a conventional method makes it easy to synthesize particles having a small particle diameter and a narrow distribution, but in the present invention, silver particles having a wide distribution and a large particle diameter can be obtained. Finally, it is possible to obtain a thick film conductive sintered body excellent in low temperature sinterability and low in resistance.
On the other hand, when the molar ratio is less than 0.7, flat particles are easily formed and easily aggregated, so that the dispersion stability of the silver coating composition becomes low.
〔４．有機溶媒（ｃ）の説明〕
　本発明は、以上説明した銀化合物とアミン化合物の錯体形成反応を、有機溶媒の存在下で行うのが望ましい。
　これらの有機溶媒の極性をコントロールすることで、銀ナノ粒子の粒子径もコントロールできるファクターの１つである。例えば、溶媒の極性を低くすることで、（ｂ）または（ｄ）のアミン化合物が銀原子側に近づきやすくなるので、合成される銀ナノ粒子のサイズは小さくなりやすい傾向を持つ。本発明では、極性の官能基を持っている溶媒が好ましく、具体的には、アルコール系溶媒、ケトン系溶媒、アルデヒド系溶媒、アミド系溶媒、エスエル系溶媒、ニトリル系溶媒が好ましい。特にアルコール系溶媒が好ましく、中でも炭素数３～１２のアルコールが好ましい。例えば、ｎ－プロパノール（沸点ｂｐ：９７℃）、イソプロパノール（ｂｐ：８２℃）、ｎ－ブタノール（ｂｐ：１１７℃）、イソブタノール（ｂｐ：１０７．８９℃）、ｓｅｃ－ブタノール（ｂｐ：９９．５℃）、ｔｅｒｔ－ブタノール（ｂｐ：８２．４５℃）、ｎ－ペンタノール（ｂｐ：１３６℃）、ｎ－ヘキサノール（ｂｐ：１５６℃）、ｎ－オクタノール（ｂｐ：１９４℃）、２－オクタノール（ｂｐ：１７４℃）、ｎ－ノナノール（ｂｐ：２１５℃）、５－ノナノール（ｂｐ：１９５℃）、ｎ－デカノール（ｂｐ：２３２．９℃）、ｎ－ウンデカノール（ｂｐ：２４３℃）、２－ウンデカノール（ｂｐ：１３１℃）、ｎ－ドデカノール（ｂｐ：２５９℃）、２－ドデカノール（ｂｐ：２５０℃）等が挙げられる。
　これらの中でも、後に行われる錯化合物の熱分解工程の温度を高くできること、銀ナノ粒子の形成後の後処理での利便性を考慮して、ｎ－ブタノール、ｎ－ヘキサノール、ｎ－デカノールが好ましい。これら単独で用いても良いし、２種類以上混同して用いてもよい。 [4. Description of Organic Solvent (c)]
In the present invention, it is desirable to carry out the complex formation reaction of the silver compound and the amine compound described above in the presence of an organic solvent.
By controlling the polarity of these organic solvents, the particle size of silver nanoparticles is also one of the factors that can be controlled. For example, since the amine compound of (b) or (d) tends to approach the silver atom side by lowering the polarity of the solvent, the size of the silver nanoparticle to be synthesized tends to decrease. In the present invention, a solvent having a polar functional group is preferable, and specifically, alcohol solvents, ketone solvents, aldehyde solvents, amide solvents, SEL solvents, nitrile solvents are preferable. In particular, alcohol solvents are preferable, and alcohols having 3 to 12 carbon atoms are particularly preferable. For example, n-propanol (bp bp: 97 ° C.), isopropanol (bp: 82 ° C.), n-butanol (bp: 117 ° C.), isobutanol (bp: 107.89 ° C.), sec-butanol (bp: 99. 5 ° C), tert-butanol (bp: 82.45 ° C), n-pentanol (bp: 136 ° C), n-hexanol (bp: 156 ° C), n-octanol (bp: 194 ° C), 2-octanol (Bp: 174 ° C.), n-nonanol (bp: 215 ° C.), 5-nonanol (bp: 195 ° C.), n-decanol (bp: 232.9 ° C.), n-undecanol (bp: 243 ° C.), 2 -Undecanol (bp: 131 ° C), n-dodecanol (bp: 259 ° C), 2-dodecanol (bp: 250 ° C) and the like.
Among these, n-butanol, n-hexanol, and n-decanol are preferable in consideration of the fact that the temperature of the thermal decomposition step of the complex compound to be performed later can be increased and the convenience in post-treatment after formation of silver nanoparticles is taken into consideration. . These may be used alone or in combination of two or more.
（４－１．有機溶媒の添加量について）
　また、有機溶媒は、各成分の十分な撹拌操作のため、前記銀化合物（ａ）１００重量部に対し、８０～１３０重量部（すなわち有機溶媒(c)と銀化合物(a)との重量比(c)/(a)）が０.８～１．３となるように有機溶媒を混合したものが好ましい。さらに好ましくは銀化合物１００重量部に対し８０～１２５重量部である。 (4-1. Addition amount of organic solvent)
In addition, the organic solvent is 80 to 130 parts by weight (that is, the weight ratio of the organic solvent (c) to the silver compound (a)) with respect to 100 parts by weight of the silver compound (a) for sufficient stirring operation of each component. What mixed the organic solvent so that (c) / (a) may be 0.8-1.3 is preferable. More preferably, it is 80 to 125 parts by weight with respect to 100 parts by weight of the silver compound.
（４－２．有機溶媒の添加方法について）
　本発明において、アミン化合物（ｂ）または（ｄ）と銀化合物（ａ）とを銀化合物とアミン化合物の錯体形成反応を、有機溶媒の存在下で行うには、いくつかの形態をとり得る。
　例えば、固体の銀化合物と有機溶媒特にアルコール溶媒とを混合して、銀化合物―アルコールスラリーを得て、次に得られた銀化合物－アルコールスラリーに、アミン化合物（ｂ）または（ｄ）を添加してもよい。本発明においてスラリーとは、固体の銀化合物が有機溶媒または有機溶媒とアミン化合物との混液中に分散されている混合物を表している。スラリーを得るには、反応容器に、固体の銀化合物を仕込み、それに有機溶媒または有機溶媒とアミン化合物との混液を添加しスラリーを得ると良い。 (4-2. Regarding the addition method of the organic solvent)
In the present invention, in order to carry out the complex formation reaction of an amine compound (b) or (d) and a silver compound (a) with a silver compound and an amine compound in the presence of an organic solvent, several forms can be taken.
For example, a solid silver compound and an organic solvent, particularly an alcohol solvent, are mixed to obtain a silver compound-alcohol slurry, and then an amine compound (b) or (d) is added to the obtained silver compound-alcohol slurry. You may In the present invention, the slurry represents a mixture in which a solid silver compound is dispersed in an organic solvent or a mixture of an organic solvent and an amine compound. In order to obtain a slurry, it is preferable to charge a solid silver compound in a reaction vessel and add an organic solvent or a mixture of an organic solvent and an amine compound thereto to obtain a slurry.
　あるいは、有機溶媒とアミン化合物との混液を反応容器に仕込み、それに銀化合物を添加しても良い。
　尚、シュウ酸銀については、乾燥状態において爆発性があることが報告されている。したがって、銀化合物としてシュウ酸銀を用いる場合には、湿潤状態にしたものを利用するのが好ましい。湿潤状態にすることで爆発性が著しく低下し、取扱い性が容易になるためである。そこで、水又は前述した有機溶媒を混合して湿潤状態にして用いればよい。 Alternatively, a mixture of an organic solvent and an amine compound may be charged into a reaction vessel, and a silver compound may be added thereto.
Silver oxalate has been reported to be explosive in the dry state. Therefore, when using silver oxalate as a silver compound, it is preferable to use what was made into the wet state. The wet state significantly reduces the detonability and facilitates the handling. Therefore, water or the above-mentioned organic solvent may be mixed and used in a wet state.
〔５．脂肪族カルボン酸について〕
　また、粒子径、粒度分布の調整のために、錯形成時に脂肪族カルボン酸を用いてもよい。脂肪族カルボン酸を添加することで、粒子径は小さく、粒度分布は狭くなる傾向にある。水分量と適宜調整し、利用することが望ましい。前記脂肪族カルボン酸は前記アミン類と共に用いるとよく、銀化合物とアミンを混合させる際に添加して用いることもできる。前記脂肪族カルボン酸としては、飽和又は不飽和の脂肪族カルボン酸が用いられる。例えば、ブタン酸、ペンタン酸、ヘキサン酸、ヘプタン酸、オクタン酸、ノナン酸、デカン酸、ウンデカン酸、ドデカン酸、トリデカン酸、テトラデカン酸、ペンタデカン酸、ヘキサデカン酸、ヘプタデカン酸、オクタデカン酸、ノナデカン酸、イコサン酸、エイコセン酸等の炭素数４以上の飽和脂肪族モノカルボン酸；  オレイン酸、エライジン酸、リノール酸、パルミトレイン酸等の炭素数８以上の不飽和脂肪族モノカルボン酸が挙げられる。 [5. About aliphatic carboxylic acid]
Moreover, you may use aliphatic carboxylic acid at the time of complex formation for adjustment of particle diameter and particle size distribution. The addition of the aliphatic carboxylic acid tends to reduce the particle size and narrow the particle size distribution. It is desirable to adjust the water content appropriately and use it. The aliphatic carboxylic acid may be used together with the amines, and may be added and used when mixing a silver compound and an amine. As the aliphatic carboxylic acid, a saturated or unsaturated aliphatic carboxylic acid is used. For example, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, Examples thereof include saturated aliphatic monocarboxylic acids having 4 or more carbon atoms such as icosanoic acid and eicosenic acid; and unsaturated aliphatic monocarboxylic acids having 8 or more carbon atoms such as oleic acid, elaidic acid, linoleic acid, and palmitoleic acid.
　これらの内でも、炭素数８～１８の飽和又は不飽和の脂肪族モノカルボンが好ましい。炭素数８以上とすることにより、カルボン酸基が銀粒子表面に吸着した際に他の銀粒子との間隔を確保できるため、銀粒子同士の凝集を防ぐ作用が向上する。入手のし易さ、焼成時の除去のし易さ等を考慮して、通常、炭素数１８までの飽和又は不飽和の脂肪族モノカルボン酸化合物が好ましい。特に、オクタン酸、オレイン酸等が好ましく用いられる。前記脂肪族カルボン酸のうち、１種のみを用いてもよく、２種以上を組み合わせて用いてもよい。 Among these, C 8-18 saturated or unsaturated aliphatic monocarboxylic acids are preferable. By setting the number of carbon atoms to 8 or more, when the carboxylic acid group is adsorbed on the surface of the silver particles, a space between the silver particles and the other silver particles can be secured, so that the effect of preventing aggregation of silver particles is improved. In view of easy availability, easy removal at the time of firing, etc., a saturated or unsaturated aliphatic monocarboxylic acid compound having up to 18 carbon atoms is usually preferred. In particular, octanoic acid, oleic acid and the like are preferably used. Among the aliphatic carboxylic acids, only one type may be used, or two or more types may be used in combination.
（５－２．脂肪族カルボン酸の添加量について）
　前記脂肪族カルボン酸は、用いる場合には、原料の前記銀化合物の銀原子１モルに対して、例えば０．０５～１０モル程度用いるとよく、好ましくは０．１～５モル、より好ましくは０．５～２モル用いるとよい。前記脂肪族カルボン酸の量が、前記銀原子１モルに対して、０．０５モルよりも少ないと、前記脂肪族カルボン酸の添加による粒子径制御の効果が弱い。一方、前記脂肪族カルボン酸の量が１０モルに達すると、粒子径が小さく揃いすぎる可能性もあるし、洗浄もしくは、表面保護剤置換工程においても、残存する可能性があるので、低温焼成での該脂肪族カルボン酸の除去がされにくくなる。ただし、脂肪族カルボン酸を用いなくてもよい。 (5-2. Regarding the amount of aliphatic carboxylic acid added)
When used, the aliphatic carboxylic acid may be, for example, about 0.05 to 10 moles, preferably 0.1 to 5 moles, and more preferably about 1 mole to 1 mole of silver atoms of the silver compound as a raw material. It is preferable to use 0.5 to 2 moles. When the amount of the aliphatic carboxylic acid is less than 0.05 mol with respect to 1 mol of the silver atom, the effect of particle diameter control by the addition of the aliphatic carboxylic acid is weak. On the other hand, when the amount of the aliphatic carboxylic acid reaches 10 moles, the particle diameter may be too small and may remain even in the washing or surface protection agent replacement step, so low temperature baking is preferable. It becomes difficult to remove the aliphatic carboxylic acid. However, aliphatic carboxylic acid may not be used.
〔６．水・水分量の説明〕
　本発明では、（ｂ１）成分のアミン化合物とともに、水を用いてもよい。反応系の水分含有量は、銀化合物１００重量部に対して５～２０重量部以下の範囲内とするのが好適である。特に好ましくは１５重量部以下である。水分含有量については、錯形成に使用するアミン化合物の種類にもよるが、水分含有量が少ないと、得られる銀粒子の粒度分布が揃い、焼結体の空隙が生まれ、本発明で期待される効果が発現しにくいことがある。一方、銀化合物に対して２０重量部を超える水分含有量の場合、銀粒子が粗大になりすぎ、粒子が焼結・合一する部分が生まれ、好ましくない。使用する水に関しては、金属イオン不純物を低減したイオン交換水が好ましい。水を添加するタイミングについては、加熱工程の前であればよく、銀－アミン錯体の形成前、あるいは錯体形成後の、いずれの段階で添加してもよい。
　また、前述した有機溶媒（ｃ）と水との比率は、水／有機溶媒の重量比が０．０３～０．３が好ましい。より好ましくは０．１～０．２５である。この範囲で特に、本発明の効果を得るのが容易である。 [6. Explanation of water and moisture content]
In the present invention, water may be used together with the amine compound of the component (b1). The water content of the reaction system is preferably in the range of 5 to 20 parts by weight or less with respect to 100 parts by weight of the silver compound. Particularly preferably, it is at most 15 parts by weight. The water content depends on the kind of amine compound used for complex formation, but when the water content is small, the particle size distribution of the obtained silver particles is uniform, and voids of the sintered body are produced, which is expected in the present invention May be difficult to develop. On the other hand, when the water content is more than 20 parts by weight with respect to the silver compound, the silver particles become too coarse, and portions where the particles sinter and coalesce are generated, which is not preferable. With regard to water to be used, ion-exchanged water with reduced metal ion impurities is preferred. Water may be added before the heating step, and may be added at any stage before the formation of the silver-amine complex or after the complex formation.
The ratio of the organic solvent (c) to water described above is preferably such that the weight ratio of water / organic solvent is 0.03 to 0.3. More preferably, it is 0.1 to 0.25. Within this range, in particular, it is easy to obtain the effects of the present invention.
（６－１．水添加することにおける高分布銀粒子生成のメカニズムについて）
　後述する熱分解による銀粒子形成の反応中、水を存在させることにより、形成される銀ナノ粒子の粒径に特にバラつきが生じ、高分布な銀粒子が得られる。そのメカニズムについては、不明な部分もあるが、水が銀化合物、特にシュウ酸銀に近づき、銀アミン錯体形成または、加熱分解する際に、アミン化合物が銀原子へ吸着するのを阻害し、阻害された部分が粒子成長すると考えられる。さらに、この水分子のシュウ酸銀への吸着量も偏りがある（局在化している）ことから、粒径に適度なバラつきが生じると考える。このための適切な量が、銀化合物１００重量部に対して５重量部以上である。逆に、銀化合物１００重量部に対して２０重量部よりも多い量の水を添加すると、銀粒子自体が肥大化し、隣の粒子とも焼結・合一を起こしてしまうことがある。これは、水がアミンの銀原子の吸着を阻害して銀粒子が肥大化するためと推測される。 6-1. Mechanism of formation of highly distributed silver particles in water addition
During the reaction of formation of silver particles by thermal decomposition described later, the presence of water causes variation particularly in the particle diameter of the formed silver nanoparticles, and highly distributed silver particles are obtained. The mechanism is unclear, but there is a part that water approaches the silver compound, especially silver oxalate, and prevents the amine compound from being adsorbed to the silver atom during silver amine complex formation or thermal decomposition. It is believed that the portion that has been Furthermore, since the amount of adsorption of water molecules to silver oxalate is also biased (localized), it is considered that the particle diameter is appropriately dispersed. An appropriate amount for this is 5 parts by weight or more with respect to 100 parts by weight of the silver compound. On the other hand, if water is added in an amount of more than 20 parts by weight with respect to 100 parts by weight of the silver compound, the silver particles themselves may be enlarged, and the adjacent particles may be sintered and coalescence. It is presumed that this is because water inhibits the adsorption of the silver atom of the amine and the silver particles are enlarged.
＜銀ナノ粒子の製造方法＞
〔７．液体原料の混合〕
　本発明において、通常は、前記極性溶媒（ｃ）の中に、前記錯体形成するアミン化合物（ｂ）を入れ、混合する。必要に応じて、脂肪族カルボン酸、水を添加・混合し、反応に必要な液体原料を調整することができる。
　液体原料で、常温で固体の物質があった場合は、適宜加熱を行い混合する事もできる。加熱する温度としては、１００℃以下、好ましくは、８０℃以下、さらに好ましくは、６０℃以下で加熱し、液状化する液体原料の構成が望ましい。前記温度域よりも高い温度だと、銀化合物と混ぜてスラリー化する場合に、先に一部錯体化・シュウ酸分解反応が始まってしまい、系内の均一性が確保されないまま銀ナノ粒子が生成されてしまう可能性がある。 <Method of producing silver nanoparticles>
[7. Mixing of liquid raw materials]
In the present invention, usually, the amine compound (b) to be complexed is placed in the polar solvent (c) and mixed. If necessary, aliphatic carboxylic acid and water can be added and mixed to adjust the liquid raw material necessary for the reaction.
When there is a substance which is a liquid raw material and is solid at normal temperature, it can be appropriately heated and mixed. The heating temperature is preferably 100 ° C. or less, preferably 80 ° C. or less, more preferably 60 ° C. or less, and the configuration of the liquid raw material to be liquefied is desirable. If the temperature is higher than the above temperature range, when the slurry is mixed with a silver compound, a partial complexation / oxalic acid decomposition reaction starts first, and the silver nanoparticles are not obtained while maintaining the uniformity in the system. It may be generated.
〔８．銀化合物スラリーの作製〕
　前記銀化合物（ａ）と前記液体原料を混合し、銀化合物スラリーを調製する。または、先に極性溶媒と前記銀化合物（ａ）のみを混合し、前記アミン化合物を後で添加してもよい。 [8. Preparation of silver compound slurry]
The silver compound (a) and the liquid raw material are mixed to prepare a silver compound slurry. Alternatively, only the polar solvent and the silver compound (a) may be mixed first, and the amine compound may be added later.
　銀化合物と、所定量のアミン混合液、または、必要に応じて脂肪族カルボン酸、水を混合する。この際の混合は、室温で撹拌しながら、あるいは銀化合物へのアミン類との配位反応（錯体化反応）は発熱を伴うため室温以下に適宜冷却して撹拌しながら行うとよい。銀化合物とアミン化合物等との混合液は、極性溶媒存在下にて行われるので、撹拌及び冷却は良好に行うことができる。極性溶媒とアミン化合物の過剰分が反応媒体の役割を果たす。 A silver compound and a predetermined amount of an amine mixture, or, if necessary, an aliphatic carboxylic acid and water are mixed. The mixing at this time may be carried out while stirring at room temperature, or the coordination reaction (complexation reaction) of the silver compound with the amine with an amine is accompanied by heat generation and appropriately cooled while stirring below room temperature. The mixed solution of the silver compound and the amine compound and the like is performed in the presence of a polar solvent, so that stirring and cooling can be well performed. The excess of polar solvent and amine compound acts as a reaction medium.
　それと、揮発性の高いアルキルアミンの臭気は作業環境への悪影響が大きい、本発明においては、銀ナノ粒子合成時に使用する揮発性の高いアルキルアミンの量を軽減、または無くすことができるので、原料を仕込む際に臭気や作業者への暴露を軽減できる。 Besides, the odor of the highly volatile alkylamine has a great adverse effect on the working environment. In the present invention, the amount of highly volatile alkylamine used at the time of silver nanoparticle synthesis can be reduced or eliminated. Can reduce odor and exposure to workers when preparing
〔９．銀アミン錯体について〕
　生成する錯化合物が一般にその構成成分に応じた色を呈するので、反応混合物の色の変化から、錯化合物の生成反応の進行を検知することができる。また、色の変化で確認がとりにくい場合、反応混合物の粘性の変化や、温度の変化などで生成状態を検知することができる。このようにして、極性溶媒及びアミン化合物を主体とする媒体中に銀アミン錯体が得られる。 [9. About silver amine complex]
Since the complex compound to be formed generally exhibits a color corresponding to its constituent components, the progress of the reaction for forming the complex compound can be detected from the change in color of the reaction mixture. In the case where confirmation is difficult due to a change in color, the generation state can be detected by a change in viscosity of the reaction mixture or a change in temperature. In this way, a silver amine complex is obtained in a polar solvent and a medium based on an amine compound.
〔１０．錯体化から分解反応までの昇温速度条件の説明〕
　反応系の加熱工程において、加熱速度は析出する銀粒子の粒径に影響を及ぼすことから、加熱工程の加熱速度の調整により銀粒子の粒径をコントロールすることができる。ここで、加熱工程の速度は、設定した分解温度まで、３．０～５０℃／ｍｉｎの範囲で調整することが望ましい。昇温時間が遅い方が、粒子成長が起こりやすく大粒子径が形成されやすいが、３．０℃／ｍｉｎよりも遅い昇温速度であると、粒子成長が促進されやすく、隣の粒子とも同一してしまい、好ましくない。 [10. Explanation of temperature rising rate conditions from complexation to decomposition reaction]
In the heating process of the reaction system, the heating rate affects the particle size of the deposited silver particles, so that the particle size of the silver particles can be controlled by adjusting the heating rate of the heating process. Here, it is desirable to adjust the speed of the heating step in the range of 3.0 to 50 ° C./min up to the set decomposition temperature. If the temperature rise time is slow, particle growth easily occurs and a large particle size is easily formed, but if the temperature rise rate is slower than 3.0 ° C./min, particle growth is easily promoted and the same as the next particle is also the same. It is not preferable.
〔１１．銀粒子の洗浄工程について〕
　銀化合物の熱分解により、得られた粒子の粒子径により、色が異なるが、黒褐色からグレーまでの色に呈する懸濁液となる。この懸濁液から極性溶媒や過剰のアミン化合物等の除去操作、例えば、銀ナノ粒子の沈降、適切な溶媒（水または、有機溶媒）によるデカンテーション・洗浄操作を行うことによって、目的とする保護剤としてアミン化合物が結合した銀ナノ粒子が得られる。 [11. About the cleaning process of silver particles]
By the thermal decomposition of the silver compound, the color of the obtained particles varies depending on the particle size of the particles, but a suspension giving a blackish brown to gray color is obtained. Removal of polar solvent, excess amine compound, etc. from this suspension, for example, precipitation of silver nanoparticles, decantation with suitable solvent (water or organic solvent), and targeted protection Silver nanoparticles to which an amine compound is bound as an agent are obtained.
〔１２．洗浄溶媒の説明〕
　この銀粒子の洗浄は、溶媒としてメタノール、エタノール、プロパノール等の沸点が１５０℃以下のアルコールを適応するのが好ましい。そして、洗浄の詳細な方法としては、銀粒子合成後の溶液に溶媒を加え、懸濁するまで撹拌した後、デカンテーションで上澄み液を除去することが好ましい。アミンの除去量は、加える溶媒の体積と洗浄回数で制御可能である。上述の一連の作業を線回数１回とする場合、好ましくは、銀粒子合成後の溶液に対して１／２０～３倍の体積の溶媒を使用し、１～５回洗浄する。 [12. Description of washing solvent]
In washing of the silver particles, it is preferable to use, as a solvent, an alcohol having a boiling point of 150 ° C. or less such as methanol, ethanol or propanol. And as a detailed method of washing, after adding a solvent to a solution after silver particle synthesis and stirring until suspension, it is preferable to remove the supernatant liquid by decantation. The amount of amine removed can be controlled by the volume of solvent added and the number of washes. In the case where the above-described series of operations is performed once in the number of lines, preferably, washing is performed 1-5 times using a solvent having a volume of 1/20 to 3 times that of the solution after silver particle synthesis.
〔１３．保護剤置換工程〕
　さらに、上記の銀ナノ粒子に対して、必要に応じて炭素数４以上のアミン化合物（酸素原子を含むものも可）に表面保護剤を置換させる工程により、用途に合ったアミン化合物へ置換してもよい。最終的に置換するアミン化合物は、銀ナノ粒子を製造する際に用いたものでもよいし、用いていないものを新たに使用してもよい。洗浄後の銀粒子を最終的に置換したいアミン化合物の中で、一定時間撹拌・懸濁することで、銀粒子の表面保護剤が置換される。その際、含まれている純銀分に対して、最終的に置換したいアミン化合物を５０～１００ｗｔ％添加して、約１ｈ常温下で撹拌・懸濁させる。表面保護剤置換工程の前後の違いについては、ＤＴＡ測定での焼結由来ピークの違いや、ヘッドスペースＧＣ／ＭＳなどで、表面保護剤の確認は可能である。上述した表面保護剤の置換工程後、再度洗浄工程を経て、目的の銀粒子を得る。 [13. Protective agent substitution process]
Furthermore, if necessary, an amine compound suitable for the application is substituted for the above-mentioned silver nanoparticles by the step of substituting a surface protective agent with an amine compound having 4 or more carbon atoms (which may contain an oxygen atom). May be The amine compound to be finally substituted may be one used when producing silver nanoparticles, or one not used may be newly used. The surface protective agent of the silver particles is replaced by stirring and suspending the washed silver particles for a certain period of time in the amine compound to be finally substituted. At that time, 50 to 100 wt% of the amine compound to be finally substituted is added to the contained pure silver, and the mixture is stirred and suspended for about 1 hour under normal temperature. About the difference before and behind a surface protection agent substitution process, the confirmation of a surface protection agent is possible by the difference of the sintering origin peak in DTA measurement, head space GC / MS, etc. After the step of replacing the surface protective agent described above, the target silver particles are obtained through the washing step again.
　ここで用いるアミン化合物としては、炭素数４～８のアルキルアミンまたは、酸素原子を含むアミン化合物（アルコキシアミン、アルキルエーテルアミン、アミノアルコール）である。その中でも、分子の長さが５～８Åであるものが好ましく、さらに好ましいのは、分子の長さが７～８Åのものである。アルキルアミンと、酸素原子を含むアミン化合物は、１種類もしくは２種類以上併用しても可能であり、その組成によって、ペーストに加工した際の粘性の調整も可能となる。 The amine compound used here is an alkylamine having 4 to 8 carbon atoms or an amine compound containing an oxygen atom (alkoxyamine, alkyl ether amine, amino alcohol). Among them, those having a molecule length of 5 to 8 Å are preferable, and those having a molecule length of 7 to 8 Å are more preferable. The alkylamine and the amine compound containing an oxygen atom can be used alone or in combination of two or more kinds, and depending on the composition thereof, it is also possible to adjust the viscosity when processed into a paste.
〔１４．生成された銀粒子の状態（保護剤、粒度分布）〕
　このようにして、用いたアミン化合物が保護剤として結合された銀ナノ粒子が形成される。銀ナノ粒子とは、以下の方法で製造されうる、銀成分を主体として通常１～１０００ｎｍの粒径を有する微細な粒子をいう。 [14. State of silver particles produced (protective agent, particle size distribution))
In this way, silver nanoparticles are formed in which the amine compound used is bound as a protective agent. Silver nanoparticles refer to fine particles having a particle size of usually 1 to 1000 nm mainly composed of a silver component, which can be produced by the following method.
　前記保護剤は、例えば、前記の特定の炭素数４以下のアミノアルコール（ｂ）を含み、さらに分子の長さが５Å以上のアミン化合物（ｄ）を含み、さらに用いた場合は前記脂肪族カルボン酸を含んでいる。保護剤中におけるそれらの含有割合は、前記アミン混合液中のそれらの使用割合と同等である。また、洗浄工程、必要であれば保護剤置換行程によって、保護剤の種類や総量を調整することが可能である。最終的に保護剤として結合しているアミン化合物の分子の長さは、２～８Åが好ましく、さらに５～８Åがより好ましい。そして、７～８Åが最も好ましい。一方、保護剤の総量は純銀分１００重量部に対して、０．３～２．０重量部であることが好ましい。さらに０．５～１．０重量部であればより好ましい。 The protective agent includes, for example, the amino alcohol (b) having the specific carbon number of 4 or less, further includes an amine compound (d) having a molecular length of 5 Å or more, and the aliphatic carbon when used. Contains acid. Their content in the protective agent is equivalent to their use in the amine mixture. In addition, it is possible to adjust the type and total amount of the protective agent by the washing step, and if necessary, the protective agent replacement step. The length of the molecule of the amine compound finally bonded as a protecting agent is preferably 2 to 8 Å, more preferably 5 to 8 Å. And, 7-8 Å is most preferable. On the other hand, the total amount of the protective agent is preferably 0.3 to 2.0 parts by weight with respect to 100 parts by weight of pure silver. More preferably, it is 0.5 to 1.0 parts by weight.
　本発明の銀ナノ粒子は、通常、粒子径が１０００ｎｍ以下である。
　また、平均粒子径が７０～３５０ｎｍ、好ましくは７０～３００ｎｍ、さらに好ましくは８０～２００ｎｍである。
　粒子径のばらつきを示す変動係数は３０～８０％、好ましくは４０～７０％、さらに好ましくは５０～６０％で構成されている。 The silver nanoparticles of the present invention generally have a particle size of 1000 nm or less.
Also, the average particle size is 70 to 350 nm, preferably 70 to 300 nm, and more preferably 80 to 200 nm.
The coefficient of variation indicating the variation in particle diameter is made to be 30 to 80%, preferably 40 to 70%, and more preferably 50 to 60%.
　平均粒子径及び変動係数は、以下のようにして求める。得られた銀ナノ粒子をＦＥ－ＳＥＭにて粒子形状の観察を行う。その後画像解析ソフトＳＣＡＮＤＩＵＭ（ＯＬＹＭＰＵＳ製）を用いて、３００個以上の粒子径の測長し、平均粒子径、標準偏差の値を解析により求めた。これらの値を用いて、変動係数は以下の計算式に基づき計算した。
　変動係数（％）＝{標準偏差（ｎｍ）／平均粒子径（ｎｍ）}×１００
　なお粒子径測定の機材は、上記の方法と同等の結果を得られるものであれば制限されない。 The average particle size and the coefficient of variation are determined as follows. The particle shape of the obtained silver nanoparticles is observed by FE-SEM. Thereafter, using the image analysis software SCANDIUM (manufactured by OLYMPUS), the particle diameters of 300 or more particles were measured, and the values of the average particle diameter and the standard deviation were determined by analysis. Using these values, the coefficient of variation was calculated based on the following formula.
Coefficient of variation (%) = {standard deviation (nm) / average particle size (nm)} x 100
The equipment for measuring the particle size is not limited as long as the same results as those described above can be obtained.
　以上の平均粒子径と分布（ばらつき）を有することにより、銀塗料を塗布して得られる塗膜の膜厚を厚くすることができる。具体的には、１０～３０μｍもの厚膜も得ることができる。さらに、厚いだけでなく、得られる膜の体積抵抗率も低くすることができる。具体的には、２０μｍ以上の厚膜で、２０～３０μΩ・ｃｍ程度の体積抵抗率を得ることができる。これは、粒度分布が広く、小さい粒子が大きい粒子の間に最密充填に近く充填されることにより、銀粒子が高充填されて銀粒子の含有量の高い膜が得られているためであると推測される。 By having the above-mentioned average particle diameter and distribution (variation), the film thickness of the coating film obtained by apply | coating a silver coating material can be thickened. Specifically, a thick film of 10 to 30 μm can also be obtained. In addition to being thick, the volume resistivity of the resulting film can also be lowered. Specifically, a volume resistivity of about 20 to 30 μΩ · cm can be obtained with a thick film of 20 μm or more. This is because silver particles are highly filled and a film with a high content of silver particles is obtained by being closely packed with close-packing between large particles with a wide particle size distribution. It is guessed.
　平均粒子径が７０ｎｍ未満だと、銀粒子の表面を保護するアミン化合物量が増え、得られる塗膜の体積抵抗率を低くするのが難しい。他方、平均粒子径が３５０ｎｍを超えると、銀ナノ粒子の融点降下の現象が弱くなり、低温で焼結しづらくなるため、この場合も塗膜の体積抵抗率を低くすることが難しくなる。
　また、変動係数が３０％未満だと、粒子が揃ってしまい、粒子間の空隙を埋めることができず、塗膜の体積抵抗率を低くすることが難しくなる。他方、変動係数が８０％を超えると、粒子のばらつきがあっても、粒子サイズが異なりすぎるため、この場合も粒子間の空隙を埋めることが難しくなり、この場合も塗膜の体積抵抗率を低くすることが難しくなる。 When the average particle size is less than 70 nm, the amount of amine compound protecting the surface of silver particles is increased, and it is difficult to lower the volume resistivity of the obtained coating. On the other hand, if the average particle size exceeds 350 nm, the phenomenon of melting point depression of silver nanoparticles weakens and it becomes difficult to sinter at low temperature, so it is also difficult to lower the volume resistivity of the coating in this case.
If the coefficient of variation is less than 30%, the particles become uniform, and the gaps between the particles can not be filled, making it difficult to lower the volume resistivity of the coating. On the other hand, if the coefficient of variation exceeds 80%, even if there is particle dispersion, the particle size will be too different, and in this case it is also difficult to fill the gaps between particles, and in this case also the volume resistivity of the coating It will be difficult to lower it.
　このため以上の平均粒子径とばらつきとを有する銀粒子とすることが好ましいが、本発明を用いれば、このような銀粒子を容易に得ることができ、したがって銀塗料組成物として好適な粘度に調整することができる。
　スクリーン印刷用インクの粘度においては、０．１～５００Ｐａ・ｓの範囲（ずり速度５ １／ｓｅｃ 時）が好ましい。高すぎると、流動性がなく印刷不良を起こしやすい、また低すぎると印刷したインクがダレて、線幅が広がってしまうためである。そこで、粘度を高くするには、通常、有機バインダーを添加することが多いが、有機バインダーは得られる塗膜の抵抗値を上げてしまう。これに対し、本発明の銀粒子は、有機バインダーとしてエトセル４５（日新化成製）を純銀分に対し、１ｗｔ％添加した状態でも比較的高粘度とすることができ、例えば粒度を平均粒子径約８０ｎｍ、変動係数約３５％に調整することにより、３０～４０Ｐａ・ｓ程度の粘度に調整できる。したがって有機バインダーの添加量が純銀分に対し、１ｗｔ％以下でも上記のスクリーン印刷に適した粘度にすることができる。このように、粒度の調整で粘度をコントロールできるので、有機バインダーの添加量の自由度が上がり、少なくすることもできるため、非常に優れている。 For this reason, it is preferable to use silver particles having the above average particle size and variations, but such silver particles can be easily obtained by using the present invention, and therefore, the viscosity is suitable as a silver coating composition. It can be adjusted.
The viscosity of the screen printing ink is preferably in the range of 0.1 to 500 Pa · s (at a shear rate of 51 / sec). If it is too high, there is no flowability and printing defects are likely to occur, and if it is too low, the printed ink will sag and the line width will spread. Therefore, in order to increase the viscosity, an organic binder is usually added in many cases, but the organic binder raises the resistance value of the obtained coating film. On the other hand, the silver particles of the present invention can have a relatively high viscosity even when 1 wt% of Etocel 45 (manufactured by Nisshin Kasei Co., Ltd.) is added to the pure silver as an organic binder. The viscosity can be adjusted to about 30 to 40 Pa · s by adjusting to about 80 nm and the coefficient of variation to about 35%. Therefore, even if the addition amount of the organic binder is 1 wt% or less based on the pure silver content, the viscosity suitable for the above screen printing can be obtained. As described above, since the viscosity can be controlled by adjusting the particle size, the degree of freedom of the addition amount of the organic binder can be increased and the amount can be reduced, which is very excellent.
　本発明の製造方法は、前述したように、使用するアミン種、有機溶媒種、水の添加量等で、粒子径コントロールが可能である。したがって、２００～５００ｎｍの大粒子径領域の銀粒子と５０～２００ｎｍの小粒子径領域の銀粒子を１バッチで合成することもできるなど、工業生産にも適している。 As described above, the production method of the present invention can control the particle size depending on the type of amine used, the type of organic solvent, the amount of water added, and the like. Therefore, it is also suitable for industrial production, for example, silver particles in the large particle size range of 200 to 500 nm and silver particles in the small particle size range of 50 to 200 nm can be synthesized in one batch.
　こうして得られる銀粒子は、２００ｎｍ以上の大粒子径領域の銀粒子が存在しているため、銀ナノ粒子の余剰保護剤の洗浄・保護剤置換処理・ペースト化などの工程途中においても凝集（焼結）しにくく、本来の銀粒子の特性を損ねることなく、銀ナノ粒子分散体・銀塗料組成物を製造しやすいと期待できる。このことは、スケールアップを考慮した際も有効である。 Since silver particles obtained in this way have silver particles in the large particle size region of 200 nm or more, they are aggregated (baked out during the processes such as cleaning / substituting agent substitution / pasting of excess protective agent of silver nanoparticles as well). It can be expected that the silver nanoparticle dispersion / silver paint composition can be easily produced without being hard to break and impairing the original characteristics of the silver particles. This is also effective when scaling up is considered.
＜用途＞
〔１５．銀ナノ粒子分散体及び銀塗料組成物及びこれらの製造方法〕
　上記に記載の方法で得られた銀ナノ粒子を用いて、銀ナノ粒子分散体を作製することができる。ここで、銀ナノ粒子分散体とは、少なくとも銀ナノ粒子及び分散媒を含有する組成物をいう。このような銀ナノ粒子分散体は、制限されることなく、種々の形態をとり得る。例えば、銀ナノ粒子を適切な有機溶媒（分散媒体）中に懸濁状態で分散させることにより、銀ナノ粒子分散体を得ることができる。
　本発明で得られる銀ナノ粒子は分散性に優れているため、高濃度で分散媒中に安定に存在させることができる。例えば、組成物中の銀ナノ粒子の含有量として、７０～９５重量％、さらに好ましくは７５～８０重量％の高濃度で含有させることができ、いわゆるペースト状態とすることができる。
　さらに、銀ナノ粒子及び分散媒のほか、いわゆるバインダー成分を含有させた銀塗料組成物を作製することができる。７０～９５重量％、さらに好ましくは７５～８０重量％の高濃度で銀ナノ粒子を含有させることにより、印刷性が良好で、厚膜な導電膜が作製しやすい銀塗料組成物とすることができる。 <Use>
[15. Silver nanoparticle dispersion, silver paint composition and method for producing them]
A silver nanoparticle dispersion can be produced using the silver nanoparticles obtained by the method described above. Here, the silver nanoparticle dispersion refers to a composition containing at least silver nanoparticles and a dispersion medium. Such silver nanoparticle dispersions can take various forms without limitation. For example, a silver nanoparticle dispersion can be obtained by dispersing silver nanoparticles in a suitable organic solvent (dispersion medium) in a suspended state.
The silver nanoparticles obtained in the present invention are excellent in dispersibility, and can be stably present in the dispersion medium at high concentration. For example, the content of silver nanoparticles in the composition can be contained at a high concentration of 70 to 95% by weight, more preferably 75 to 80% by weight, and it can be in the so-called paste state.
Furthermore, in addition to silver nanoparticles and a dispersion medium, a silver coating composition can be produced which contains a so-called binder component. By containing silver nanoparticles at a high concentration of 70 to 95% by weight, more preferably 75 to 80% by weight, a silver coating composition having good printability and easy formation of a thick conductive film is provided. it can.
（１５－１．分散体又は塗料組成物の分散媒）
　銀ナノ粒子分散体又は銀塗料組成物を得るための分散媒としては各種の有機溶媒、例えばペンタン、ヘキサン、ヘプタン、オクタン、ノナン、デカン、ウンデカン、ドデカン、トリデカン、テトラデカン等の脂肪族炭化水素溶媒；　シクロヘキサン、メチルシクロヘキサン等の脂環式炭化水素溶媒；トルエン、キシレン、メシチレン等のような芳香族炭化水素溶媒；　メタノール、エタノール、プロパノール、ｎ－ブタノール、ｎ－ペンタノール、ｎ－ヘキサノール、ｎ－ヘプタノール、ｎ－オクタノール、ｎ－ノナノール、ｎ－デカノール、ｎ－ドデカノール等のようなアルコール溶媒等が挙げられる。 (15-1. Dispersion medium of dispersion or coating composition)
Various organic solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, dodecane, tridecane, tetradecane and the like can be used as a dispersion medium for obtaining a silver nanoparticle dispersion or a silver coating composition. Alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; aromatic hydrocarbon solvents such as toluene, xylene, mesitylene and the like; methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, n- Alcohol solvents such as heptanol, n-octanol, n-nonanol, n-decanol, n-dodecanol etc. may be mentioned.
　有機溶媒としてはこれらの中でも特に、炭素数８～１６で構造内に酸素原子を有する沸点２８０℃以下の有機溶媒が好ましい。銀粒子の焼結温度の目標を１５０℃以下とする場合、沸点２８０℃を超える溶媒は揮発・除去が困難だからである。この溶媒の好ましい具体例としては、ターピネオール（Ｃ１０、沸点２１９℃）、ジヒドロターピネオール（Ｃ１０、沸点２２０℃）、テキサノール（Ｃ１２、沸点２６０℃）、エチルカルビトールアセテート（Ｃ８、沸点２１９℃）、ブチルカルビトールアセテート（Ｃ１０、沸点２４７℃）、２，４－ジメチルー１，５－ペンタンジオール（Ｃ９、沸点１５０℃）、２，２，４－トリメチル－１，３－ペンタンジオールジイソブチレート（Ｃ１６、沸点２８０℃）が挙げられる。溶媒は複数種を混合して使用しても良く、単品で使用しても良い。
　所望の銀塗料組成物又は銀ナノ粒子分散体の濃度や粘性に応じて、有機溶媒の種類や量を適宜定めると良い。 Among these, as the organic solvent, an organic solvent having 8 to 16 carbon atoms and an oxygen atom in the structure and having a boiling point of 280 ° C. or less is preferable. When the target of the sintering temperature of silver particles is 150 ° C. or less, the solvent having a boiling point of 280 ° C. or more is difficult to volatilize and remove. Preferred specific examples of this solvent include terpineol (C10, boiling point 219 ° C.), dihydroterpineol (C10, boiling point 220 ° C.), texanol (C12, boiling point 260 ° C.), ethyl carbitol acetate (C8, boiling point 219 ° C.), butyl Carbitol acetate (C10, boiling point 247 ° C.), 2,4-dimethyl-1,5-pentanediol (C9, boiling point 150 ° C.), 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (C16, Boiling point 280 ° C.). The solvent may be used as a mixture of two or more kinds, or may be used alone.
The type and amount of the organic solvent may be appropriately determined in accordance with the concentration and viscosity of the desired silver coating composition or silver nanoparticle dispersion.
（１５－２．塗料組成物の有機バインダーの説明）
　銀塗料組成物に対して、銀粒子の分散性の補助、又は基材との密着性を付与する目的で、有機バインダーを添加しても良い。有機バインダーの添加量としては、含有している銀１００重量部に対して、０.１～１０重量部が好ましい。
　上記バインダー樹脂の導電性インク中における存在形態は、溶媒に対して溶解していてもよいし、エマルジョン、またはサスペンションであってもよい。上記バインダー樹脂としては特に限定されないが、例えば、ポリエステル樹脂、ポリウレタン樹脂、ポリアミド樹脂、ポリ塩化ビニル樹脂、ポリアクリルアミド樹脂、ポリエーテル樹脂、アクリル樹脂、メラミン樹脂、ビニル樹脂、フェノール樹脂、エポキシ樹脂、尿素樹脂、酢酸ビニル樹脂、ポリブタジエン樹脂、塩化ビニル酢酸ビニル共重合体樹脂、フッ素樹脂、シリコン樹脂、ロジン、ロジンエステル、塩素化ポリオレフィン樹脂、変性塩素化ポリオレフィン樹脂、塩素化ポリウレタン樹脂、セルロース系樹脂、ポリエチレングリコール、ポリエチレンオキサイド、ポリプロピレンオキサイド、ポリビニルアルコール、ポリビニルプチラール、ポリビニルピロリドンなどを挙げることができる。
　使用するバインダー樹脂は１種単独で用いてもよいし、２種以上を併用して用いてもよい。 (Description of Organic Binder of Coating Composition)
An organic binder may be added to the silver coating composition in order to aid the dispersibility of silver particles or to provide adhesion to a substrate. The addition amount of the organic binder is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of contained silver.
The form of the binder resin in the conductive ink may be dissolved in a solvent, or may be an emulsion or a suspension. The binder resin is not particularly limited. For example, polyester resin, polyurethane resin, polyamide resin, polyvinyl chloride resin, polyacrylamide resin, polyether resin, acrylic resin, melamine resin, vinyl resin, phenol resin, epoxy resin, urea Resin, vinyl acetate resin, polybutadiene resin, vinyl vinyl acetate copolymer resin, fluorine resin, silicone resin, rosin, rosin ester, chlorinated polyolefin resin, modified chlorinated polyolefin resin, chlorinated polyurethane resin, cellulose resin, polyethylene Examples include glycol, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone and the like.
The binder resin to be used may be used individually by 1 type, and may be used in combination of 2 or more types.
〔１６．銀塗料組成物による印刷方法・使い方）〕
　調製された銀塗料組成物を基板上に塗布し、その後、焼成するのが一般的である。
　塗布は、スピンコート、インクジェット印刷、スクリーン印刷、ディスペンサ印刷、凸版印刷（フレキソ印刷）、昇華型印刷、オフセット印刷、レーザープリンタ印刷（トナー印刷）、凹版印刷（グラビア印刷）、コンタクト印刷、マイクロコンタクト印刷などの公知の方法により行うことができる。印刷技術を用いると、パターン化された銀塗料組成物層が得られ、焼成により、パターン化された銀導電層が得られる。また、この銀導電層は導電性・熱伝導性に優れた接合材料としての応用が可能であり、パワーデバイス等の大電流を取扱う電気機器の接合材としても有用である。 [16. Method of printing with silver paint composition)
It is common to apply the prepared silver coating composition onto a substrate and then bake it.
Application is spin coating, ink jet printing, screen printing, dispenser printing, letterpress printing (flexo printing), sublimation printing, offset printing, laser printer printing (toner printing), intaglio printing (gravure printing), contact printing, micro contact printing Etc. can be carried out by known methods. Using printing techniques, a patterned silver paint composition layer is obtained, and upon firing, a patterned silver conductive layer is obtained. In addition, this silver conductive layer can be applied as a bonding material excellent in conductivity and thermal conductivity, and is also useful as a bonding material for electric devices that handle large currents such as power devices.
　焼成は、２００℃以下、例えば室温（２５℃）以上１５０℃以下、好ましくは室温（２５℃）以上１２０℃以下の温度で行うことができる。しかしながら、短い時間での焼成によって、銀の焼結を完了させるためには、６０℃以上２００℃以下、例えば８０℃以上１５０℃以下、好ましくは９０℃以上１２０℃以下の温度で行うとよい。焼成時間は、銀インクの塗布量、焼成温度などを考慮して、適宜定めるとよく、たとえば数時間（例えば３時間、あるいは２時間）以内、好ましくは１時間以内、より好ましくは３０分間以内にするとよい。
　銀ナノ粒子は上記のように構成されているので、このような低温短時間での焼成工程によっても、銀粒子の焼結が十分に進行する。その結果、平均粒子径が２００ｎｍを超えても優れた導電性（低い抵抗値）が発現する。低い抵抗値（例えば２０～３０μΩ・ｃｍ）を有する銀導電層が形成される。バルク銀の抵抗値は１．６μΩｃｍである。 The baking can be performed at a temperature of 200 ° C. or less, for example, room temperature (25 ° C.) or more and 150 ° C. or less, preferably room temperature (25 ° C.) or more and 120 ° C. or less. However, in order to complete the sintering of silver by baking for a short time, it is preferable to carry out at a temperature of 60 ° C. to 200 ° C., for example, 80 ° C. to 150 ° C., preferably 90 ° C. to 120 ° C. The baking time may be appropriately determined in consideration of the coated amount of silver ink, baking temperature, etc., for example, within several hours (for example, 3 hours or 2 hours), preferably within 1 hour, more preferably within 30 minutes. It is good.
Since the silver nanoparticles are configured as described above, sintering of silver particles proceeds sufficiently even with such a low temperature and short time baking process. As a result, excellent conductivity (low resistance value) is exhibited even when the average particle diameter exceeds 200 nm. A silver conductive layer having a low resistance value (eg, 20 to 30 μΩ · cm) is formed. The resistance value of bulk silver is 1.6 μΩcm.
〔１７．銀ナノ粒子分散体及び銀塗料組成物の用途〕
　低温での焼成が可能であるので、基板として、ガラス製基板、ポリイミド系フィルムのような耐熱性プラスチック基板の他に、ポリエチレンテレフタラート（PET）フィルム、ポリエチレンナフタレート（PEN）フィルムなどのポリエステル系フィルム、ポリプロピレンなどのポリオレフィン系フィルムのような耐熱性の低い汎用プラスチック基板をも好適に用いることができる。また、短時間の焼成は、これら耐熱性の低い汎用プラスチック基板に対する負荷を軽減するし、生産効率を向上させる。 [17. Applications of silver nanoparticle dispersion and silver paint composition]
Since baking is possible at low temperature, polyester-based materials such as polyethylene terephthalate (PET) film and polyethylene naphthalate (PEN) film as well as glass substrates and heat-resistant plastic substrates such as polyimide-based films can be used as substrates. A low heat resistant general purpose plastic substrate such as a film or a polyolefin-based film such as polypropylene can also be suitably used. In addition, the baking for a short time reduces the load on the low-heat-resistance general-purpose plastic substrate and improves the production efficiency.
　銀導電層の厚みは、目的とする用途に応じて適宜定めるとよく、特に本発明に係る銀ナノ粒子を使用することで比較的膜厚の大きい銀導電層を形成した場合でも高い導電性を示すことができる。銀導電層の厚みは、例えば、１００ｎｍ～３０μｍ、好ましくは１μｍ～２０μｍ、より好ましくは１０μｍ～２０μｍの範囲から選択するとよい。 The thickness of the silver conductive layer may be appropriately determined in accordance with the intended application, and particularly high conductivity can be obtained even when the silver conductive layer having a relatively large film thickness is formed by using the silver nanoparticles according to the present invention. Can be shown. The thickness of the silver conductive layer may be selected, for example, in the range of 100 nm to 30 μm, preferably 1 μm to 20 μm, and more preferably 10 μm to 20 μm.
　本発明の銀ナノ粒子分散体又は銀塗料組成物により得られる銀導電材料は、電磁波制御材、回路基板、アンテナ、放熱板、液晶ディスプレイ、有機ELディスプレイ、フィールドエミッションディスプレイ（FED）、ICカード、ICタグ、太陽電池、LED素子、有機トランジスタ、コンデンサー（キャパシタ）、電子ペーパー、フレキシブル電池、フレキシブルセンサ、メンブレンスイッチ、タッチパネル、EMIシールド等に適応することができる。 The silver conductive material obtained by the silver nanoparticle dispersion or silver paint composition of the present invention includes an electromagnetic wave control material, a circuit board, an antenna, a heat sink, a liquid crystal display, an organic EL display, a field emission display (FED), an IC card, The present invention can be applied to an IC tag, a solar cell, an LED element, an organic transistor, a capacitor (capacitor), an electronic paper, a flexible battery, a flexible sensor, a membrane switch, a touch panel, an EMI shield, and the like.
　以下、実施例及び比較例により本発明をさらに具体的に説明する。
　実施例及び比較例で用いたアミン化合物の名称、構造式等の特徴を、表－１～２に示す。 Hereinafter, the present invention will be more specifically described by examples and comparative examples.
The characteristics of the names, structural formulas and the like of the amine compounds used in Examples and Comparative Examples are shown in Tables 1 and 2.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
  
Figure JPOXMLDOC01-appb-T000002
  
［実施例１］
（銀粒子の製造）
　アルミブロック式加熱攪拌機にセットした試験管に原料となる銀化合物としてシュウ酸銀の乾燥品７．５８ｇ（２４．９５ｍｍｏｌ） と、極性溶媒としてｎ－ヘキサノール９．２１ｇ（９０．１４ｍｍｏｌ）とを撹拌し、シュウ酸銀を湿潤状態にさせた。その後、DL-‐１‐アミノ－２－プロパノール２．１１ｇ（２８．０９ｍｍｏｌ）、オレイン酸０．３０g（１．０６ｍｍｏｌ）を添加した。その後、１時間撹拌し、銀―アミン錯体を製造した。その後、昇温速度３℃／ｍｉｎで加熱し１００℃でシュウ酸銀の分解反応が起こったと思われる二酸化炭素の発生を確認した。二酸化炭素の発生が止まるまで加熱を継続し、銀粒子が懸濁された液体を得た。銀粒子の析出後、反応液にメタノール２０ｃｃを添加して洗浄し、これを遠心分離した。この洗浄と遠心分離は３回行った。このようにして、銀ナノ粒子を得た。 Example 1
(Manufacturing of silver particles)
In a test tube set in an aluminum block type heating stirrer, 7.58 g (24.95 mmol) of a dried silver oxalate product as a silver compound as a raw material and 9.21 g (90.14 mmol) of n-hexanol as a polar solvent are stirred in a test tube set in an aluminum block heating stirrer. And the silver oxalate was allowed to wet. Thereafter, 2.11 g (28.09 mmol) of DL-1-amino-2-propanol and 0.30 g (1.06 mmol) of oleic acid were added. Thereafter, the mixture was stirred for 1 hour to produce a silver-amine complex. After that, heating was performed at a temperature rising rate of 3 ° C./min, and the generation of carbon dioxide at 100 ° C., which is considered to cause the decomposition reaction of silver oxalate, was confirmed. Heating was continued until generation of carbon dioxide ceased, and a liquid in which silver particles were suspended was obtained. After precipitation of silver particles, 20 cc of methanol was added to the reaction solution to wash it, and this was centrifuged. The washing and centrifugation were performed three times. Silver nanoparticles were thus obtained.
（粒子径の確認）
　得られたメタノールで湿った状態の銀ナノ粒子をｎ－ヘキサノール中へボルテックスミキサーを用いて懸濁させ、その液をコロジオン膜等の支持体へ滴下し、溶媒を乾燥させて試料を得た。ＦＥ－ＳＥＭ観察にて、倍率２００００～７００００倍で観察・撮影し、画像の中で４００個以上粒子が存在している倍率の画像を選定する。その後、ＦＥ－ＳＥＭにて粒子形状の観察を行った。その後画像解析ソフトＳＣＡＮＤＩＵＭ（ＯＬＹＭＰＵＳ製）を用いて、粒子数４００個以上をカウントし、粒子径の測長、平均粒径、粒度分布等の解析を実施した。粒子に長径とそれ以外の径がある場合は粒子径の測長は長径を測長した。
　粒子の１００～２００ｎｍの粒子割合（％）、平均粒径（ｎｍ）、変動係数（％）を表－５に示す。ＦＥ－ＳＥＭ写真を図３に示す。粒度分布ヒストグラムを図２１に示す。 (Confirmation of particle size)
The resulting silver nanoparticles in a wet state with methanol were suspended in n-hexanol using a vortex mixer, the solution was dropped onto a support such as a collodion membrane, and the solvent was dried to obtain a sample. In FE-SEM observation, observation and imaging are performed at a magnification of 20000 to 70000, and an image having a magnification of 400 or more particles in the image is selected. Thereafter, the particle shape was observed by FE-SEM. Thereafter, the number of particles was counted at 400 or more using image analysis software SCANDIUM (manufactured by OLYMPUS), and analysis of length measurement of particle diameter, average particle diameter, particle size distribution and the like was performed. When the particles had a major axis and other diameters, the major axis was measured.
The particle ratio (%) of 100 to 200 nm of particles, the average particle diameter (nm), and the variation coefficient (%) are shown in Table 5. An FE-SEM photograph is shown in FIG. The particle size distribution histogram is shown in FIG.
（銀ナノ粒子ペースト、インクの調製と焼成）
　次に、回収した銀ナノ粒子に、溶媒としてテキサノールを銀分７５ｗｔ％になるよう添加し、混合した。さらに銀粒子に対して添加量が１ｗｔ％になるように、有機バインダーとしてエトセル４５（日新化成製）を添加し、最終的に銀分約７０ｗｔ％の銀ナノ粒子ペーストインクを作製した。このペーストをスライドガラス上でキャストし、送風乾燥機にて、１５０℃で１ｈ加熱した。乾燥後の塗膜厚みは１０~３０μｍになるようにした。
　得られた塗膜は、４端子法により表面抵抗値を測定し、得られた塗膜の厚みを乗じて、体積抵抗率を得た。
　体積抵抗率の値を表－４に示す。 (Silver nanoparticle paste, preparation and baking of ink)
Next, texanol as a solvent was added to the recovered silver nanoparticles so as to have a silver content of 75 wt% and mixed. Furthermore, Etocel 45 (manufactured by Nisshin Kasei Co., Ltd.) was added as an organic binder so that the addition amount was 1 wt% to silver particles, and a silver nanoparticle paste ink having a silver content of about 70 wt% was finally prepared. The paste was cast on a slide glass and heated at 150 ° C. for 1 h in a blower dryer. The coating film thickness after drying was made to be 10 to 30 μm.
The surface resistance value of the obtained coating film was measured by a four-terminal method, and the thickness of the obtained coating film was multiplied to obtain a volume resistivity.
The values of volume resistivity are shown in Table 4.
［実施例２～８、比較例１～１２］
（銀粒子の製造）
　使用材料及び配合割合を表－５～１２に示すものに代え、銀―アミン錯体化合物生成後の昇温速度を表－５～１２に示すものに代え、反応容器／加熱装置を表－５～１３に示すものに代えた以外は実施例１の（銀粒子の製造）と同様にして、銀粒子を作製した。
　表－７に示すとおり、実施例８については、後述の内容の（保護剤置換処理）を行った。保護剤置換行程を以下に示す。シュウ酸銀のシュウ酸分解反応により、得られた銀ナノ粒子中のアミン化合物をｎ－ヘキシルアミンに置換するため、得られた銀ナノ粒子の純銀分に対して７１．８ｗｔ％のｎ－ヘキシルアミンと銀ナノ粒子を常温で１時間撹拌し、上記と同様に洗浄と遠心分離を３回繰り返し、ヘキシルアミンを保護剤とした銀ナノ粒子を得た。 [Examples 2 to 8, Comparative Examples 1 to 12]
(Manufacturing of silver particles)
The materials used and the mixing ratio are as shown in Table 5-12, the temperature rising rate after formation of the silver-amine complex compound is as shown in Table 5-12, and the reaction vessel / heating device is as shown in Table 5 Silver particles were produced in the same manner as in (Production of silver particles) in Example 1 except for using those shown in 13.
As shown in Table 7, (Example 8) was subjected to (protective agent substitution treatment) described later. The protective agent substitution process is shown below. In order to replace the amine compound in the obtained silver nanoparticles with n-hexylamine by the oxalic acid decomposition reaction of silver oxalate, 71.8 wt% n-hexyl based on the pure silver content of the obtained silver nanoparticles The amine and silver nanoparticles were stirred at room temperature for 1 hour, and washing and centrifugation were repeated three times in the same manner as described above to obtain silver nanoparticles using hexylamine as a protective agent.
　得られた銀粒子について実施例１と同様の方法で（粒子径の確認）を行った。なお、比較例２～４については、ＳＴＥＭ像で粒子径の確認を実施した。
　また、実施例２～８、比較例１、２、１１、１２については、得られた子を用いて実施例１と同様の方法で（銀ナノ粒子ペースト、インクの調製と焼成）を行った。
　なお実施例８については、保護剤置換処理前の粒子と保護剤置換処理後の粒子を用いて各々（銀ナノ粒子ペースト、インクの調製と焼成）を行った。
また、比較例３及び、４については、特許文献１及び、２のように、銀分５５ｗｔ％になるようにし、イソオクタン／ｎ－ブタノール＝４／１（体積比）の混合溶媒中に分散させた銀ナノ粒子分散体をスピンコートすることにより、ガラス上に塗工した。 The obtained silver particles were subjected to the same method as in Example 1 (confirmation of particle diameter). In Comparative Examples 2 to 4, the particle diameter was confirmed by STEM images.
In Examples 2 to 8 and Comparative Examples 1, 2, 11 and 12, the obtained particles were used in the same manner as in Example 1 (silver nanoparticle paste, ink preparation and baking). .
In Example 8, the particles before the protective agent substitution treatment and the particles after the protective agent substitution treatment were used (preparation of silver nanoparticle paste, ink and baking).
In Comparative Examples 3 and 4, as in Patent Documents 1 and 2, the silver content is 55 wt%, and is dispersed in a mixed solvent of iso-octane / n-butanol = 4/1 (volume ratio). The silver nanoparticle dispersion was applied onto glass by spin coating.
　実施例２～８、比較例１～４、１１，１２について、得られた粒子の平均粒径（ｎｍ）、変動係数（％）、各粒子径範囲での粒子割合（％）、を表－５～１２に示す。ＳＥＭもしくはＳＴＥＭ画像を図２～２０に示す。実施例２～８、比較例１～４、１１、１２の粒度分布ヒストグラムを図２１～３３に示す。実施例１～１０及び、比較例１～４について、焼結塗膜の体積抵抗率及び膜厚の値を表－５～１２に示す。 The average particle diameter (nm), variation coefficient (%) and particle ratio (%) in each particle diameter range of the obtained particles are shown in Tables 2 to 8 and Comparative Examples 1 to 4, 11 and 12 It shows in 5-12. SEM or STEM images are shown in FIGS. The particle size distribution histograms of Examples 2 to 8 and Comparative Examples 1 to 4, 11 and 12 are shown in FIGS. With respect to Examples 1 to 10 and Comparative Examples 1 to 4, values of volume resistivity and film thickness of the sintered coating are shown in Tables-5 to 12.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
　以上のように、本発明により、錯体形成時に（ｂ）成分のアミン化合物を添加し、合成された銀粒子を用いることで、２０μｍ以上の焼結塗膜を形成することが可能でかつ、１５０℃での焼成条件において、塗膜の体積抵抗率が５０μΩ・ｃｍ以下であり、導電性がある膜を得られることが確認できた。 As described above, according to the present invention, it is possible to form a sintered coating film of 20 μm or more by adding the amine compound of the component (b) at the time of complex formation and using the synthesized silver particles, and It was confirmed that the film having a volume resistivity of 50 μΩ · cm or less and a conductive film can be obtained under the sintering conditions at ° C.
　実施例１～３では、ジグリコールアミンと（ｂ２）成分のアミン化合物を併用している。その中でも実施例３において、ＡＭＰを使用すると、変動係数も大きくばらつきが大きくなり、小粒子径の粒子割合も多くなり、各焼成温度において、最も体積抵抗率が低い焼成膜が得られた。
　また、実施例３、４では、ジグリコールアミンの添加量を増減させているが、添加量が多い実施例４において、実施例３よりも大きな粒子径の粒子が得られた。しかも、平均粒子径が大きくなったにも関わらず、各焼成温度での焼結塗膜の体積抵抗率はほぼ変わらない結果となった。 In Examples 1 to 3, diglycolamine and the amine compound of component (b2) are used in combination. Among them, when AMP is used in Example 3, the variation coefficient also greatly varies and the ratio of particles having a small particle diameter increases, and a fired film having the lowest volume resistivity is obtained at each firing temperature.
In Examples 3 and 4, the addition amount of diglycolamine was increased or decreased, but in Example 4 in which the addition amount was large, particles having a particle diameter larger than Example 3 were obtained. And although the average particle diameter became large, it turned out that the volume resistivity of the sintering coating film in each calcination temperature hardly changes.
　実施例４～６では、（ｂ２）成分のアミンと短鎖アルキルアミン、もしくはアルキルジアミンを用いた事例で、ジグリコールアミンを用いることで、どの実施例においても、平均粒子径２００ｎｍ以上の比較的大きな粒子径を形成することができた。その中でもＡＭＰを用いた実施例４が最も変動係数が大きくばらつきのある粒子が得られた。
　実施例７、８については、ＡＭＰ、ジグリコールアミンを用いており、実施例８はさらに水を併用した。すると、さらに大粒子径化ができた。しかも大粒子径化しても、各温度における焼結塗膜の体積抵抗率は低下することはなかった。また実施例８については、へキシルアミン置換処理前後の焼結塗膜の体積抵抗率を評価したところ、ほぼ同等の性能であった。保護基の極性を変化することができるので、各種溶媒への分散性についても対応できる幅が広い粒子を合成することができた。 In Examples 4 to 6, the diglycolamine is used in the case where the amine of the component (b2) and the short-chain alkylamine or the alkyldiamine are used, and in any of the examples, the average particle diameter is relatively 200 nm or more. It was possible to form a large particle size. Among them, in Example 4 using AMP, particles having the largest variation coefficient and variation were obtained.
In Examples 7 and 8, AMP and diglycolamine were used, and in Example 8, water was additionally used. Then, the particle size was further increased. Moreover, the volume resistivity of the sintered coating at each temperature did not decrease even when the particle diameter was increased. Moreover, about Example 8, when the volume resistivity of the sintering coating film before and behind a hexylamine substitution process was evaluated, it was substantially equivalent performance. Since the polarity of the protective group can be changed, it was possible to synthesize particles having a wide range that can cope with the dispersibility in various solvents.
　比較例１では、ジグリコールアミンや（ｂ２）成分のアミン化合物を使用しない場合の銀粒子であるが、平均粒子径が６４ｎｍで、変動係数が２０．３％で、比較的小さくそろった粒子径の粒子が形成された。その結果、２０μｍ程度の厚膜焼結膜では抵抗値が大きく上がってしまう結果となった。小粒子径だと多くの保護剤成分が必要となるので、厚膜だと保護剤が残存し抵抗成分となったと考えられる。 Comparative Example 1 is a silver particle when diglycolamine or the amine compound of component (b2) is not used, but the particle diameter is relatively small with an average particle diameter of 64 nm and a variation coefficient of 20.3%. Of particles were formed. As a result, in the case of a thick-film sintered film of about 20 μm, the resistance value was significantly increased. Since a small particle size requires many protective agent components, it is considered that the protective agent remains and becomes a resistant component in a thick film.
　また、特許文献１，２の製法と同等の方法で作製した比較例２～４の粒子について、テキサノールペーストにして評価した比較例２において、焼成後に体積収縮が激しく起こり、塗膜全体にクラックが生じてしまった。また、特許文献１、２のような低粘度の分散液状態で塗工した比較例３、４では、０．５μｍ程度の焼結塗膜となってしまい、厚膜化は困難であった。 Further, in Comparative Example 2 in which the particles of Comparative Examples 2 to 4 prepared by the method equivalent to the manufacturing methods of Patent Documents 1 and 2 were evaluated as texanol paste, volume shrinkage occurred violently after firing, and the entire coating was cracked. Has occurred. Moreover, in Comparative Examples 3 and 4 coated in a low viscosity dispersion state as in Patent Documents 1 and 2, a sintered coating film of about 0.5 μm was formed, and it was difficult to form a thick film.
　比較例５～１０では、ジグリコールアミンと類似の構造を持つアミン化合物について評価を行った。まず比較例５，６では、量末端にアミノ基を有する１，５－ジアミノペンタン、比較例７では、量末端にアミノ基と水酸基を有し、構造内に２級アミノ基を持つ２－［（３－アミノプロピル）アミノ］エタノール、比較例８、９では、量末端にアミノ基とカルボン酸を有する６－アミノヘキサン酸、比較例１０では、量末端にアミノ基を有し、構造内にエーテル結合を持つ２，２－オキシビス（エチルアミン）を用いた。しかし、いずれのアミン化合物を使っても、合成時に粒子が凝集を起こしてしまい、分散可能な状態の銀粒子を得ることはできなかった。これらは、銀粒子との吸着が強い、アミノ基やカルボン酸が分子内に２つ以上あると、粒子間で吸着するため、凝集を引き起こすものと考える。水酸基は完全に銀粒子へは吸着しないものの、銀粒子へ接近する程度の程よい極性を持っているために、アミノアルコール、さらに分子内にエーテル結合を有する（ｂ１）成分、とくにジグリコールアミンが、銀粒子を凝集させることなく合成できる保護剤としての作用を発現できると考える。 In Comparative Examples 5 to 10, evaluation was performed on an amine compound having a similar structure to diglycolamine. First, in Comparative Examples 5 and 6, 1,5-diaminopentane having an amino group at the amount end, in Comparative Example 7, it has an amino group and a hydroxyl group at the amount end and has a secondary amino group in the structure (3-aminopropyl) amino] ethanol, in Comparative Examples 8 and 9, 6-aminohexanoic acid having an amino group and a carboxylic acid at the terminal end, in Comparative Example 10, having an amino group at the terminal end, in the structure 2,2-oxybis (ethylamine) having an ether bond was used. However, using any of the amine compounds, the particles aggregate during synthesis, and it has not been possible to obtain silver particles in a dispersible state. These are considered to cause aggregation because particles are adsorbed between particles if the adsorption with silver particles is strong and there are two or more amino groups or carboxylic acids in the molecule. Although the hydroxyl group does not completely adsorb to silver particles, it has an polarity that allows it to approach silver particles, so that amino alcohol and component (b1) having an ether bond in the molecule, especially diglycolamine, It is thought that the effect as a protective agent which can be synthesized without aggregating silver particles can be expressed.
　ただし、（ｂ１）成分ではない、分子の長さが５Å以上のアミノアルコールについては、保護剤としての性能はあるものの、比較例１１、１２に示すよう、銀粒子を大粒子へ成長させる効果は極めて低いと考える。おそらく、アルキルアミンと同様の直線状の配位が優勢だと考えられる。分子内にエーテル結合がない分、片末端の水酸基だけでは、Ｏ原子接近型の配位は取りづらいものと考える。
　以上の結果からわかるように、（ｂ１）成分のアミン化合物、特にジグリコールアミンを使用することにより、本発明の方法で本発明の銀ナノ粒子は、平均粒子径２００ｎｍ以上の粒子を形成しやすくなり、粒度分布に適度なバラつきを持たせることで、低抵抗な厚膜導電膜を得られやすい銀塗料組成物を作製することが可能であることがわかる。 However, for amino alcohols which are not component (b1) and have a molecular length of 5 Å or more, although they have the performance as a protective agent, as shown in Comparative Examples 11 and 12, the effect of growing silver particles into large particles is I think it is extremely low. Presumably, linear coordination similar to alkylamines would be predominant. It is considered that coordination close to the O atom is difficult to obtain only by the hydroxyl group at one end, since there is no ether bond in the molecule.
As can be seen from the above results, by using the amine compound of component (b1), particularly diglycolamine, the silver nanoparticles of the present invention can easily form particles having an average particle diameter of 200 nm or more by the method of the present invention Thus, it is understood that it is possible to produce a silver coating composition which can easily obtain a low resistance thick film conductive film by giving a suitable dispersion to the particle size distribution.
　本発明により、刺激臭の強いアミンの排出量が抑えられた方法で、大粒径で広い分布を有し、厚膜で且つ高い導電性を有する銀導電層を容易に形成することのできる銀ナノ粒子を得ることができる。 According to the present invention, it is possible to easily form a silver conductive layer having a large particle size and a wide distribution, a thick film and high conductivity by a method in which the amount of strongly irritating amine discharged is suppressed. Nanoparticles can be obtained.

Claims (10)

  1. 　熱分解性を有する銀化合物（ａ）と、（ａ）と錯体形成しうるアミン化合物（ｂ）とを有機溶媒（ｃ）中で反応させて錯体を形成し、得られた錯体を加熱して熱分解させることにより、銀ナノ粒子を形成する銀ナノ粒子の製造方法であって、（ｂ）が、直鎖状のアミノアルコールであり、その直鎖状分子の両末端にアミノ基と水酸基とを１つずつ持ち、直鎖状分子構造内に、エーテル結合を有するアミノアルコール（ｂ１）であることを特徴とする銀ナノ粒子の製造方法。 A thermally decomposable silver compound (a) and an amine compound (b) capable of forming a complex with (a) are reacted in an organic solvent (c) to form a complex, and the resulting complex is heated to A method for producing silver nanoparticles forming silver nanoparticles by thermal decomposition, wherein (b) is a linear amino alcohol, and amino groups and hydroxyl groups are provided at both ends of the linear molecule. 1. A method for producing silver nanoparticles, which is an amino alcohol (b1) having an ether bond in a linear molecular structure, having one each.
  2. 　（ｂ１）が、炭素数４以上のアミノアルコールであることを特徴とする請求項１記載の銀ナノ粒子の製造方法。 The method for producing silver nanoparticles according to claim 1, wherein (b1) is an amino alcohol having 4 or more carbon atoms.
  3. 　（ｂ１）が、ジグリコールアミンである請求項１又は２記載の銀ナノ粒子の製造方法。 The method for producing silver nanoparticles according to claim 1 or 2, wherein (b1) is diglycolamine.
  4. 　（ａ）がシュウ酸銀である請求項１～３のいずれかに記載の銀ナノ粒子の製造方法。 The method for producing silver nanoparticles according to any one of claims 1 to 3, wherein (a) is silver oxalate.
  5. 　（ａ）と（ｂ）との錯体形成反応時に、銀化合物（ａ）１００重量部に対して５～２０重量部の水を存在させることを特徴とする請求項１～４のいずれかに記載の銀ナノ粒子の製造方法。 The water according to any one of claims 1 to 4, wherein 5 to 20 parts by weight of water is present per 100 parts by weight of the silver compound (a) in the complex formation reaction of (a) and (b). Of producing silver nanoparticles.
  6. 　（ｂ）／［（ａ）に含まれる銀原子］のモル比が０．７～２．０であることを特徴とする請求項６記載の銀ナノ粒子の製造方法。 7. The method for producing silver nanoparticles according to claim 6, wherein the molar ratio of (b) / [silver atom contained in (a)] is 0.7 to 2.0.
  7. 　（ｃ）／（ａ）の重量比が０．８～１．３であることを特徴とする請求項１～６のいずれかに記載の銀ナノ粒子の製造方法。 The method for producing silver nanoparticles according to any one of claims 1 to 6, wherein the weight ratio of (c) / (a) is 0.8 to 1.3.
  8. 　請求項１～７のいずれかに記載の方法により銀ナノ粒子を作製し、得られた銀ナノ粒子を有機溶媒に分散することを特徴とする、銀ナノ粒子分散体の製造方法。 A method for producing a silver nanoparticle dispersion, which comprises producing silver nanoparticles by the method according to any one of claims 1 to 7 and dispersing the obtained silver nanoparticles in an organic solvent.
  9. 　請求項１～８のいずれかに記載の方法により銀ナノ粒子を作製し、得られた銀ナノ粒子を有機溶媒に分散し、さらに有機バインダーを添加することを特徴とする、銀塗料組成物の製造方法。 A silver coating composition comprising: preparing silver nanoparticles by the method according to any one of claims 1 to 8; dispersing the obtained silver nanoparticles in an organic solvent; and further adding an organic binder. Production method.
  10. 　請求項８記載の方法により得られた銀ナノ粒子分散体又は請求項９記載の方法により得られた銀塗料組成物を基板上に塗布し、焼成して銀導電層を形成する工程を含む銀導電材料の製造方法。 A silver nanoparticle dispersion body obtained by the method according to claim 8 or a silver coating composition obtained by the method according to claim 9 is coated on a substrate and fired to form a silver conductive layer. Method of manufacturing conductive material.
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