JPWO2015122430A1 - Method for producing metal nanoparticles - Google Patents

Abstract

The method of the present invention is a method for producing metal nanoparticles by reacting a composition containing a metal compound (a) and an amine compound (b), wherein the content of the amine compound (b) in the composition is a metal compound. In this method, the amount of metal atoms contained in (a) is in the range of more than about 0 mol and 1 mol or less with respect to 1 mol of the metal atom. According to the method of the present invention, metal nanoparticles can be obtained that give a conductive ink or paste for printed electronics that has a small amount of residue after firing and develops high conductivity by low-temperature treatment.

Description

  The present invention relates to a method for producing metal nanoparticles.

  In recent years, “printed electronics”, which is a new circuit formation (patterning) method that replaces the conventional plating method and vapor deposition-photolithography method and directly forms circuits by printing, has attracted attention as the next-generation industrial base. ing. This technology forms a desired circuit pattern by printing a conductive paste or conductive ink on a substrate, from basic circuit components such as thin film transistors, resistors, inductors, capacitors, batteries, and displays. It can be widely applied to many application products such as sensors, RFID (Radio Frequency Identification), and solar cells. The adoption of printed electronics is expected to dramatically simplify the manufacturing process of electronics-related products, reduce time, and achieve further resource and energy savings at the same time.

  Although both glass substrates and polymer films can be used for printed electronics, if a PET (Polyethylene terephthalate) film can be used among the film substrates, it is considered that the appeal to the market will increase in terms of cost. . However, in general, the heat resistance of a PET film is said to be about 120 ° C., and a conductive paste or conductive ink that can provide sufficient conductivity and adhesion to a substrate by heat treatment at a temperature not exceeding this temperature. Development is required. Various proposals have been made to satisfy the above requirements, and among these, nano-sized metal nanoparticles are considered promising because they are excellent in low-temperature sinterability and conductivity.

  In general, nanoparticle means particles having an average particle diameter of 1 nm to 100 nm. Particularly in the case of noble metal nanoparticles, the melting temperature is significantly lower than that of bulk metal due to the nano-size effect due to the increase in surface energy in addition to its high electrical conductivity, thus lowering the processing temperature during the circuit formation process. In order to achieve this, a material having a smaller average particle diameter has been aimed at. On the other hand, nanoparticles with a small average particle size become unstable and easily aggregate due to an increase in surface energy. Therefore, when used as a material such as various conductive inks or conductive pastes during the production of nanoparticles. Problems such as precipitation and solid-liquid separation occurred. In order to prevent this, various studies have been made on techniques for coating nanoparticles with various protective layers. As a result, it has become possible to produce and use extremely minute metal nanoparticles having a size of 10 nm or less.

  Patent Document 1 describes a method for preparing metal nano-particles by using silver oxide as a raw material and preparing metal silver particles having an average particle diameter of 3 nm to 20 nm by a reduction reaction in a liquid phase.

In Patent Document 2, silver having an average particle diameter D _TEM : 3 to 20 nm or an X-ray crystal particle diameter D _X : 1 to 20 nm coated with a film containing a primary amine having an unsaturated bond and a molecular weight of 200 to 400 is disclosed. A step of mixing a silver particle dispersion in which particles are monodispersed in an organic medium and hexylamine (mixing step), and a step of generating precipitated particles by maintaining the mixed solution at 5 to 80 ° C. in a stirred state ( Settling process), and a production method having a process (solid-liquid separation process) of recovering the precipitated particles as a solid content by solid-liquid separation operation is described, and an average particle diameter by TEM measurement of silver particles obtained in Examples Are silver particles of 3 to 20 nm.

  In Patent Document 3, an amine mixed solution containing an alkylamine having 6 or more carbon atoms and an alkylamine having 5 or less carbon atoms and a metal compound containing a metal atom are mixed to contain the metal compound and the amine. There is described a method for producing coated metal fine particles, comprising a first step of producing a complex compound and a second step of decomposing the complex compound by heating to produce metal fine particles, It is disclosed that the obtained silver fine particles have an average particle diameter of 30 nm or less. However, the average particle diameter of the coated metal fine particles obtained in the examples measured by a transmission electron microscope (TEM) and a dynamic light scattering (DLS) particle diameter measuring apparatus is 20 nm or less.

  The manufacturing method described above still has the following problems. When metal nanoparticles having an average particle size of 20 nm or less are produced and used for conductive ink, the surface of the metal nanoparticles is organic molecules or the like in order to uniformly disperse highly cohesive metal nanoparticles in the conductive ink. It is necessary to be coated with. However, since the specific surface area of the metal nanoparticle increases as the average particle diameter of the metal nanoparticle decreases, the amount of organic molecules covering the surface of the metal nanoparticle increases. Therefore, when a circuit pattern is formed using the metal nanoparticles, organic molecules remain in the circuit, and the original conductivity of the metal nanoparticles cannot be obtained.

  Therefore, as a method for producing metal nanoparticles having an average particle diameter of 20 nm or more, Patent Document 4 discloses metal colloidal particles containing metal nanoparticles (A) and a dispersant (B), wherein the metal nanoparticles ( A) is a metal in a solvent in the presence of metal colloidal particles containing metal nanoparticles having a number average particle size of 50 nm or less and a particle size of 100 to 200 nm, and a dispersant (B) and / or a precursor thereof. A method for producing metal colloidal particles comprising the steps of reducing a compound to produce metal colloidal particles, producing aggregates of metal colloidal particles as precipitates, and separating and recovering the aggregates produced in this step Is described. However, since the manufacturing method described in Patent Document 4 uses a polymer dispersant, it is necessary to remove the polymer dispersant by heat treatment at about 300 ° C. in order to obtain conductivity. Become. Therefore, the use for a film base material is restricted.

Japanese Patent No. 4660766 Japanese Patent No. 5371247 JP 2012-162767 A JP 2010-229544 A

  An object of the present invention is to provide a production method capable of efficiently producing metal nanoparticles having an average particle diameter of about 20 nm or more and 200 nm or less, wherein a circuit pattern formed using the metal nanoparticles has high electrical conductivity. It is an issue to provide.

In order to solve the above-mentioned problems, the present inventor repeated research and obtained the following knowledge.
(i) It contains a metal compound (a) and an amine compound (b), and the content of the amine compound (b) exceeds 0 mol to 1 mol with respect to 1 mol of the metal atom contained in the metal compound (a). By reacting the following composition, metal nanoparticles having an average particle size of about 20 to 200 nm can be efficiently produced.
(ii) The conductive paste or ink containing the metal nanoparticles has good conductivity.
(iii) Since the metal nanoparticle has a large average particle size, a circuit or the like can be formed by heat treatment at a relatively short time or at a relatively low temperature when blended in a conductive paste or ink.

The present invention has been completed based on the above findings and provides the following production method.
Item 1. It is a manufacturing method of the metal nanoparticle which makes the composition containing a metal compound (a) and an amine compound (b) react, Comprising: Content of the amine compound (b) in a composition is contained in a metal compound (a) The method is characterized by being in the range of more than 0 mol and not more than 1 mol with respect to 1 mol of the metal atom.
Item 2. Item 2. The method according to Item 1, wherein the composition further comprises an organic solvent (c) that dissolves 1 g / L or more in water at 20 ° C.
Item 3. Item 3. The production method according to Item 2, wherein the organic solvent (c) comprises a solvent having an ether bond and a hydroxyl group.
Item 4. Item 4. The method according to Item 2 or 3, wherein the organic solvent (c) contains at least one solvent selected from the group consisting of glycol ethers and alcohols having an alkoxy group.
Item 5. Item 5. The production method according to any one of Items 1 to 4, wherein the metal compound (a) is a metal oxalate salt.
Item 6. Item 6. The production method according to any one of Items 1 to 5, wherein the amine compound (b) is at least one selected from the group consisting of a primary amine and a diamine compound having a primary amine and a tertiary amine.
Item 7. Item 7. The method according to any one of Items 1 to 6, wherein the composition further contains a fatty acid (d).
Item 8. Item 8. The method according to Item 7, wherein the content of the fatty acid in the composition is from 0.1 parts by weight to 15 parts by weight with respect to 1 part by weight of the metal compound (a).
Item 9. Item 9. The production method according to any one of Items 1 to 8, wherein the reaction is a thermal decomposition reaction at a temperature of 50 ° C to 250 ° C.
Item 10. Item 10. A metal nanoparticle having an average particle size of 20 nm to 200 nm obtained by the production method according to any one of Items 1 to 9.
Item 11. Item 10. A conductive ink composition or a conductive paste containing metal nanoparticles obtained by the production method according to any one of Items 1 to 9.
Item 12. Item 12. A circuit wiring or electrode formed using the conductive ink composition according to Item 11, or a conductive paste.

  According to the present invention, the metal compound (a) and the amine compound (b) are contained, and the amine compound (b) exceeds about 0 mol and 1 mol with respect to 1 mol of the metal atom contained in the metal compound (a). By reacting the composition contained in the following range, it is possible to efficiently produce metal nanoparticles having a larger average particle diameter than before. Furthermore, when the conductive ink or conductive paste is manufactured using the metal nanoparticle manufactured according to the present invention, the dispersion stability of the metal nanoparticle in the conductive paste is good. In addition, since the metal nanoparticles obtained by the method of the present invention have a small amount of remaining organic molecules covering the surface, heat treatment can be performed in a short time or at a relatively low temperature by using a conductive ink or paste containing the metal nanoparticles. A circuit pattern or an electrode exhibiting high electrical conductivity can be obtained only by the above. Therefore, the present invention can provide an extremely excellent printed electronics material.

4 is a SEM (scanning electron microscope) photograph of silver nanoparticles obtained in Example 4. 4 is a SEM (scanning electron microscope) photograph of silver nanoparticles obtained in Example 5. 2 is a SEM (scanning electron microscope) photograph of silver nanoparticles obtained in Comparative Example 1. 4 is a SEM (scanning electron microscope) photograph of silver nanoparticles obtained in Comparative Example 2.

  Hereinafter, the present invention will be described in detail.

Composition used in the method for producing metal nanoparticles The composition used in the production method of the present invention contains a metal compound (a) and an amine compound (b), and the content of the amine compound (b) in the composition is: It is characterized by being in the range of more than about 0 mol and 1 mol or less with respect to 1 mol of the metal atom contained in the metal compound (a). By using the above composition in the production method of the present invention, metal nanoparticles having an average particle size of about 20 nm to 200 nm (for example, about 20 nm to 150 nm, particularly about 20 nm to 100 nm) are obtained. Can be manufactured.

In addition, the average particle diameter of the metal nanoparticle in the present invention is an average value (D _SEM ) of long sides of 20 particles measured from an image of a scanning electron microscope (SEM). In the present invention, metal nanoparticles having a _DSEM of about 20 nm to 200 nm (for example, about 20 nm to 150 nm, particularly about 20 nm to 100 nm) are preferable. The metal nanoparticles in the above average particle diameter range are advantageous for producing a conductive ink or a conductive paste having good conductivity.

  The composition used in the production method of the present invention may further contain an organic solvent (c). When the composition contains the organic solvent (c), it becomes easy to uniformly mix the metal compound (a) and the amine compound (b) in the composition, the thermal decomposition reaction proceeds efficiently, and efficiently. Metal nanoparticles are generated.

  The metal nanoparticles obtained in the present invention are coated with a protective layer on the surface of the metal nanoparticles in order to prevent aggregation in the conductive ink or conductive paste and to disperse them well in a desired solvent. It is necessary. Therefore, the composition used for the production method of the present invention contains an amine compound (b) that can be a protective layer together with the metal compound (a).

  The composition used in the production method of the present invention can contain an additive for fine metal particles applied to printed electronics, as necessary, within a range that does not affect the effects of the present invention. Specific additives include fatty acid (d), viscosity adjusting agent, conductive additive, anti-choking agent, antioxidant, pH adjusting agent, anti-drying agent, adhesion promoter, antiseptic, antifoaming agent, leveling agent. And surfactants.

Metal compound (a)
As the metal compound (a) used in the production method of the present invention, an organic metal salt such as a metal carboxylate; an inorganic metal salt such as a metal sulfonate, thiol salt, chloride, nitrate, or carbonate Can be illustrated. Among them, organic metal salts and carbonates are preferable, and organic metal salts are more preferable in that it is easy to remove counterion-derived substances after the formation of metal nanoparticles, and formic acid, acetic acid, oxalic acid, malonic acid are particularly preferable. Carboxylic acid salts such as benzoic acid and phthalic acid are more preferred, and oxalates are even more preferred from the viewpoint of easiness of thermal decomposition.
A metal compound can be used individually or in combination of 2 or more types. A commercial item can be purchased and used for a metal compound (a).

  Examples of the metal species of the metal compound (a) include gold, silver, copper, platinum, palladium, nickel, and aluminum. Of these, gold, silver, and platinum are preferable in terms of conductivity and oxidation resistance, and silver is more preferable in terms of cost and low-temperature sinterability. Copper, nickel, and aluminum are also preferable.

As the metal compound (a) of the present invention, gold formate, silver formate, copper formate, platinum formate, palladium formate, nickel formate, aluminum formate, gold acetate, silver acetate, copper acetate, platinum acetate, palladium acetate, nickel acetate, acetic acid Aluminum, gold oxalate, silver oxalate, copper oxalate, platinum oxalate, palladium oxalate, nickel oxalate, aluminum oxalate, gold malonate, silver malonate, copper malonate, platinum malonate, palladium malonate, nickel malonate, aluminum malonate Examples thereof include gold phthalate, silver phthalate, copper phthalate, platinum phthalate, palladium phthalate, nickel phthalate, and aluminum phthalate. Of these, silver oxalate, copper oxalate, nickel oxalate, aluminum oxalate and the like are preferable.
The content of the metal compound (a) in the composition is preferably 1% by weight or more, more preferably 10% by weight or more, and still more preferably 20% by weight or more based on the entire composition. Moreover, 95 weight% or less is preferable, 80 weight% or less is more preferable, and 70 weight% or less is still more preferable.
The content of the metal compound (a) in the composition is about 1 to 95% by weight, about 1 to 80% by weight, about 1 to 70% by weight, about 10 to 95% by weight, about 10 to 80% by weight, Examples include about 10 to 70% by weight, about 20 to 95% by weight, about 20 to 80% by weight, and about 20 to 70% by weight. If it is in the said range, the effect of this invention can fully be acquired.

Amine compound (b)
The amine compound (b) used in the production method of the present invention has an ability to bind to the metal compound (a), and can form a protective layer on the surface of the metal nanoparticle when the metal nanoparticle is generated. Anything can be used without limitation.
For example, the primary amine compound (b-1), which is a compound in which one of the three hydrogen atoms of ammonia is substituted with a linear, branched, or cyclic hydrocarbon group, two of them are similarly substituted. A secondary amine compound (b-2) and a tertiary amine compound (b-3) in which three are similarly substituted can be exemplified. Among them, the ability to bind to the metal compound (a) is high, and when a conductive ink or conductive paste using the obtained metal nanoparticles is applied on a substrate, the temperature is relatively low (for example, 120 ° C. or lower). The primary amine compound (b-1) is preferable in that it is easily detached from the surface of the metal nanoparticle by the heat treatment.

  Examples of the primary amine compound (b-1) include ethylamine, n-propylamine, isopropylamine, 1,2-dimethylpropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, isoamylamine, tert -Amylamine, 3-pentylamine, n-amylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-octylamine, tert-octylamine, 2-ethylhexylamine, n-nonylamine, n-aminodecane, n-aminoundecane, n-dodecylamine, n-tridecylamine, 2-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine Linear or branched hydrocarbons such as n-oleylamine It can be exemplified an alkyl amine having. Moreover, cyclopropylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine that are alicyclic amines, aniline that is an aromatic amine, and the like can also be exemplified. Further, ether amines such as 3-isopropoxypropylamine and isobutoxypropylamine can also be exemplified.

  As the secondary amine compound (b-2), N, N-dipropylamine, N, N-dibutylamine, N, N-dipentylamine, N, N-dihexylamine, N, N-dipeptylamine, N, N-dioctylamine, N, N-dinonylamine, N, N-didecylamine, N, N-diundecylamine, N, N-didodecylamine, N, N-distearylamine, N-methyl-N-propylamine, Examples thereof include dialkyl monoamines such as N-ethyl-N-propylamine and N-propyl-N-butylamine, and cyclic amines such as piperidine.

  As the tertiary amine compound (b-3), triethylamine, tributylamine, trihexylamine, dimethyloctylamine, dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylpalmitylamine, dimethylstearylamine, dilaurylmonomethyl An amine etc. can be illustrated.

  Furthermore, in this invention, the diamine compound (b-4) which has two amino groups in one compound can also be used. Examples of the diamine compound (b-4) include ethylenediamine, N, N-dimethylethylenediamine, N, N′-dimethylethylenediamine, N, N-diethylethylenediamine, N, N′-diethylethylenediamine, 1,3-propanediamine, , 2-Dimethyl-1,3-propanediamine, N, N-dimethyl-1,3-propanediamine, N, N'-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propane Diamine, N, N′-diethyl-1,3-propanediamine, 1,4-butanediamine, N, N-dimethyl-1,4-butanediamine, N, N′-dimethyl-1,4-butanediamine, N, N-diethyl-1,4-butanediamine, N, N′-diethyl-1,4-butanediamine, 1,5-pentanediamine, 1,5-diamino-2-methylpentane, 1,6-he Examples include sundiamine, N, N-dimethyl-1,6-hexanediamine, N, N′-dimethyl-1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, and the like. .

  Among the diamine compounds (b-4), a diamine compound in which one of the amines is a primary amine and the other is a tertiary amine has excellent binding ability with the metal compound (a), and metal nanoparticles are produced. Moreover, it is preferable in that a protective layer can be easily formed on the surface of the metal nanoparticle. Examples of diamine compounds in which one is a primary amine and the other is a tertiary amine include N, N-dimethylethylenediamine, N, N-diethylethylenediamine, N, N-dimethyl-1,3-propanediamine, and N, N. -Diethyl-1,3-propanediamine, N, N-dimethyl-1,4-butanediamine, N, N-diethyl-1,4-butanediamine, N, N-dimethyl-1,6-hexanediamine, etc. It can be illustrated.

Among the amine compounds (b) described above, dispersion stability in a solvent when metal nanoparticles are used as a conductive ink or conductive paste, and can be easily detached by low-temperature heat treatment during circuit formation. N-propylamine, isopropylamine, cyclopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, cyclobutylamine, n-amylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, n-dodecylamine, n-oleylamine, N, N-dimethyl-1,3-propanediamine are preferred, n-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-dodecylamine N, N-dimethyl-1,3-propanediamine is more preferable. .
An amine compound (b) can be used individually by 1 type or in combination of 2 or more types. Specifically, one or more of (b-1), (b-2), (b-3), and (b-4) can be used, in particular, only (b-1), Only (b-4) and a combination of (b-1) and (b-4) are preferred. Furthermore, 1 or more types can be used among each group of (b-1), (b-2), (b-3), (b-4).

The content of the amine compound (b) in the composition may be in the range of more than about 0 mol and 1 mol or less with respect to 1 mol of the metal atom contained in the metal compound (a). The content of the amine compound (b) is preferably 0.1 mol or more, more preferably 0.2 mol or more, even more preferably 0.3 mol or more, with respect to 1 mol of the metal atom contained in the metal compound (a). Preferably, 0.4 mol or more is even more preferable. Moreover, 0.9 mol or less is preferable with respect to 1 mol of substance amounts of the metal atom contained in a metal compound (a), and, as for content of an amine compound (b), 0.8 mol or less is more preferable. If it is in the said range, the effect of this invention can fully be acquired.
In the composition, the content of the amine compound (b) with respect to 1 mol of the metal atom contained in the metal compound (a) is more than about 0 mol and 1 mol or less, about 0.1 mol or more and 1 mol or less, about 0.2 mol. 1 mol or less, about 0.3 mol to 1 mol, about 0.4 mol to 1 mol, about 0.1 mol to 0.9 mol, about 0.2 mol to 0.9 mol, about 0.3 mol to 0.9 mol, About 0.4 mol to 0.9 mol, about 0.1 mol to 0.8 mol, about 0.2 mol to 0.8 mol, about 0.3 mol to 0.8 mol, about 0.4 mol to 0.8 mol Can be mentioned.
The amine compound (b) contained in the composition used for production forms a circuit pattern (conductive film) by subjecting the conductive ink or conductive paste containing the obtained metal nanoparticles to heat treatment. Since most of the amine compound (b) is desorbed from the surface of the metal nanoparticle by the heat treatment, the coating film when the circuit pattern is formed even if a large amount of the amine compound (b) is added to the composition. Almost no influence on conductivity.

  The substance amount (mol) of the amine compound (b) in the present invention is the primary amine compound (b-1) obtained by substituting one, two, or three of the three hydrogen atoms of ammonia with a hydrocarbon group. ), The secondary amine compound (b-2), or the tertiary amine compound (b-3), the primary amine, secondary amine, or primary site that is coordinated to the metal compound (a) Calculation is based on the number of tertiary amines. That is, the number of moles of molecules is defined as a substance amount (mol).

In addition, the substance amount (mol) of the amine compound (b) is based on the number of primary amines and secondary amines in the diamine compound (b-4) having a primary amine and / or a secondary amine. And That is, the substance amount (mol) of a diamine compound having two primary amines or two secondary amines, or one primary amine and one secondary amine, is twice the number of moles of the molecule. .
The amount (mol) of the amine compound (b) is the number of primary amines or secondary amines in the case of a diamine compound in which one is a primary amine or secondary amine and the other is a tertiary amine. Is calculated based on That is, the number of moles of molecules is the amount of substance (mol). This is because the tertiary amine has a large steric hindrance and is difficult to coordinate with the metal compound (a), so that the primary amine or the secondary amine can be easily coordinated with the metal compound (a). This is because it is appropriate to use numbers as the basis.

Organic solvent (c)
The organic solvent (c) is not limited thereto, but preferably dissolves in an amount of about 1 g / L or more in water at 20 ° C., more preferably dissolves in an amount of about 10 g / L or more. An organic solvent having both an ether bond and a hydroxyl group in one compound (organic solvent) can be preferably used. This organic compound may have a bond other than an ether bond and a functional group other than a hydroxyl group.

Examples of the organic solvent (c) include aromatic compounds such as benzene and benzonitrile, ketones such as acetone, acetylacetone, and methyl ethyl ketone, fatty acid esters such as ethyl acetate, butyl acetate, ethyl butyrate, and ethyl formate, diethyl ether, dipropyl Ethers such as ether, dibutyl ether, tetrahydrofuran, 1,4-dioxane, halogenated hydrocarbons such as dichloromethane, chloroform, dichloroethane, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol 1,4-butanediol, 2,3-butanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-pentanediol, 1,5-pentanediol, 2-methyl-2,4 Diols such as 3-pentanediol and 3-methyl-1,5-pentanediol , Alcohols having a linear or branched alkyl having 1 to 7 carbon atoms, alcohols such as cyclohexanol, 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-butanol, polyethylene glycol, triethylene glycol monomethyl Ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 3-methoxybutyl acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol Monomethyl ether, diethylene glycol monomethyl ether acetate, Ethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl Glycol or glycol ethers such as ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, methyl-n-amyl Terpenes such as ketone, methyl ethyl ketone oxime, triacetin, γ-butyrolactone, 2-pyrrolidone, N-methylpyrrolidone, acetonitrile, N, N-dimethylformamide, N- (2-aminoethyl) piperazine, dimethyl sulfoxide, and terpineol It can be illustrated.
An organic solvent (c) may be used individually by 1 type, and 2 or more types may be mixed and used for it. It is possible to adjust the viscosity of the composition as appropriate using the organic solvent (c).

  Among them, 3-methoxy is low in that since it has a high boiling point, it is less likely to evaporate during the thermal decomposition reaction of the metal compound (a) and take heat away from the system, and each component can be well dispersed in the composition. Alcohols having an alkoxy group such as 1-butanol, 3-methoxy-3-methyl-1-butanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dipropylene glycol mono Glycol ethers such as ethyl ether and triethylene glycol monoethyl ether are preferred.

Further, the content of the organic solvent (c) in the composition is not particularly limited, but is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and 30 parts by weight with respect to 1 part by weight of the metal compound (a). Part or more is even more preferable. If it is this range, each component in a composition can be mixed uniformly.
Moreover, 1000 weight part or less is preferable with respect to 1 weight part of metal compounds (a), and, as for content of the organic solvent (c) in a composition, 500 weight part or less is preferable and 300 weight part or less is preferable. Within this range, it is possible to avoid situations where the reaction solution becomes too dilute and the reaction becomes longer or the recovery cost increases.
The content of the organic solvent (c) in the composition is about 5 to 1000 parts by weight, about 5 to 500 parts by weight, about 5 to 300 parts by weight, about 10 parts by weight with respect to 1 part by weight of the metal compound (a). -1000 weight part, about 10-500 weight part, about 10-300 weight part, about 30-1000 weight part about 30-500 weight part, and about 30-300 weight part are mentioned.

Fatty acid (d)
Fatty acid (d) may be further added to the composition used in the production method of the present invention as necessary. Since the fatty acid (d) binds strongly to the surface of the metal nanoparticles, it contributes to the improvement of the dispersibility of the metal nanoparticles in the conductive ink or conductive paste. The fatty acid (d) is not particularly limited as long as it has an ability to bind to the metal compound (a) and functions as a protective layer on the surface of the metal nanoparticle when the metal nanoparticle is generated. be able to.

The fatty acid (d) may have 3 to 18 carbon atoms, and preferably has 4 to 18 carbon atoms.
As the fatty acid (d), acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, An example is α-linolenic acid. Cyclic alkyl carboxylic acids such as cyclohexane carboxylic acid can also be used. Of these, caproic acid, 2-ethylhexylic acid, oleic acid, linoleic acid, and α-linolenic acid are preferred because of good dispersion stability in the reaction solution during the production of metal nanoparticles.
The fatty acid (d) can be used alone or in combination of two or more.

The content of the fatty acid (d) in the composition is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, and further preferably 1 part by weight or more with respect to 1 part by weight of the metal compound (a). More preferred. If it is this range, the dispersibility improvement effect of a metal nanoparticle will be fully acquired.
The content of the fatty acid (d) in the composition is preferably 15 parts by weight or less, more preferably 10 parts by weight or less, and still more preferably 8 parts by weight or less, relative to 1 part by weight of the metal compound (a). . In general, it is known that fatty acid (d) binds strongly to metal nanoparticles, and in a heat treatment usually performed when a conductive ink using metal nanoparticles or a conductive paste is applied on a substrate, Although it is hard to detach | leave, it exists in the tendency for many fatty acids contained in a composition to remain on the surface of a metal nanoparticle, but if it is the said range, the residue of the fatty acid on a board | substrate will be suppressed.
The content of the fatty acid (d) with respect to 1 part by weight of the metal compound (a) is about 0.1 part by weight to 15 parts by weight, about 0.5 part by weight to 15 parts by weight, about 1 part by weight to 15 parts by weight. Parts by weight, about 0.1 to 10 parts by weight, about 0.5 to 10 parts by weight, about 1 to 10 parts by weight, about 0.1 to 8 parts by weight, about 0.5 parts by weight or more and 8 parts by weight or less, and about 1 part by weight or more and 8 parts by weight or less are included.

  The molar ratio of the amine compound (a) to the fatty acid (d) is such that the amine compound (a): fatty acid (d) is in the range of about 90:10 to about 99.9: 0.1, and about 95: It is preferably in the range of 5 to about 99.9: 0.1, and preferably in the range of about 95: 5 to about 99.5: 0.5. If it is within the above range, it is a protective layer that can sufficiently improve the dispersibility of the metal nanoparticles, and when the conductive ink containing the metal nanoparticles or the conductive paste is applied on the substrate, the comparison is made. A protective layer that is easily detached from the surface of the metal nanoparticle can be formed by heat treatment at a low temperature.

Method for Producing Metal Nanoparticles By using the above-described composition in a method for producing metal nanoparticle exemplified below, metal nanoparticle having an average particle diameter of about 20 nm to 200 nm can be produced.

Adjustment Process The production method of the present invention can include an adjustment process of the composition, but the composition prepared in advance can also be used. The mixing method and mixing order of each component in the adjusting step are not particularly limited as long as each component is uniformly dispersed in the composition and becomes a mixed state. Examples of mixing methods include mechanical stirrers, magnetic stirrers, vortex mixers, planetary mills, ball mills, three rolls, line mixers, planetary mixers, dissolvers, etc., and these methods can be used according to the scale and capacity of the production equipment. Can be selected as appropriate from the above. In order to avoid the temperature of the composition from rising due to the effects of heat of fusion, frictional heat, etc. during mixing and initiating the thermal decomposition reaction of the metal nanoparticles, It is preferable to carry out so that it may become 60 degrees C or less, and it is more preferable to carry out, suppressing to 40 degrees C or less.

Reaction Step By subjecting the composition described above to a thermal reaction (reaction step) in a reaction vessel, a thermal decomposition reaction of the metal compound (a) occurs, and metal nanoparticles are generated. The reaction method is not particularly limited as long as it is a method usually performed in a method for producing metal nanoparticles used for printed electronics. For example, the composition may be introduced into a reaction vessel that has been heated in advance, or the composition may be heated after being introduced into the reaction vessel.

The reaction temperature of the pyrolysis reaction in the reaction step of the present invention may be a temperature at which the pyrolysis reaction proceeds and metal nanoparticles are generated, may be 50 ° C. or more, preferably 100 ° C. or more, and preferably 120 ° C. The above is more preferable. If it is this range, a metal nanoparticle will produce | generate efficiently. Moreover, the reaction temperature should just be about 250 degrees C or less, 240 degrees C or less is preferable and 230 degrees C or less is more preferable. If it is this range, volatilization of a protective layer structural component will be suppressed and a protective layer can be efficiently formed in the metal nanoparticle surface.
The reaction temperature is about 50 ° C to 250 ° C, about 100 ° C to 250 ° C, about 120 ° C to 250 ° C, about 50 ° C to 240 ° C, about 100 ° C to 240 ° C, about 120 ° C to 240 ° C. Or less, about 50 to 230 ° C., about 100 to 230 ° C., about 120 to 230 ° C.
Further, the reaction time may be appropriately selected according to the desired average particle size and the composition of the composition corresponding thereto. For example, it may be about 1 minute to 100 hours, and preferably about 1 minute to 10 hours.

The metal nanoparticle produced | generated by the refinement | purification process pyrolysis reaction is obtained as a mixture containing an unreacted raw material (an organic solvent when an organic solvent (c) is added). By purifying the mixture, the target metal nanoparticles can be obtained. Examples of the purification method include a precipitation method using the specific gravity difference between the metal nanoparticles and the organic solvent, in addition to a solid-liquid separation method by a normal filter filtration. As a specific method of solid-liquid separation, a method such as centrifugation, a cyclone method, or a decanter can be exemplified. When carrying out purification by these methods, the mixture may be diluted with a low-boiling solvent such as acetone or methanol in order to adjust the viscosity of the mixture containing metal nanoparticles.

In the production method of the present invention, metal nanoparticles having a desired average particle size can be obtained by appropriately adjusting the reaction conditions and the composition of the composition used for the reaction. For example, the average particle size can be in the range of about 20 nm to 200 nm, in the range of about 20 nm to 150 nm, and in the range of about 20 nm to 100 nm.
The metal nanoparticles obtained by the production method of the present invention can be easily dispersed in various solvents when used in a conductive ink or conductive paste. Furthermore, since a circuit formed using metal nanoparticles obtained by the production method of the present invention exhibits a low volume resistance value, it can be used for various conductive materials.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these.

(1) Each component which comprises the composition used for manufacture of the metal nanoparticle of a material Example and a comparative example is shown below.

Metal compound (a)
a1: Silver oxalate ((COOAg) ₂ )
In addition, the molar ratio of the amine compound (b) to 0.5 mol of silver oxalate (1 mol of silver atoms) was adjusted in the range of more than 0 mol and 1 mol or less. Silver oxalate was synthesized by the method described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2012-162767).

Amine compound (b)
b1: n-dodecylamine (manufactured by Wako Pure Chemical Industries, Ltd.)
b2: n-octylamine (Wako Pure Chemical Industries, Ltd.)
b3: N, N-dimethyl-1,3-propanediamine (manufactured by Wako Pure Chemical Industries, Ltd.)
b4: n-butylamine (manufactured by Wako Pure Chemical Industries, Ltd.)
n-dodecylamine, n-octylamine, N, N-dimethyl-1,3-diaminopropane, and n-butylamine are compounded at 10 mol%, 50 mol%, 5 mol%, and 35 mol%, respectively, to form an amine compound The liquid (b) liquid mixture was prepared and used for all the Examples and Comparative Examples. In addition, the molar ratio (amine compound (b) / silver atom (a1)) of the amine compound (b) solution and the silver atom (a1) in the silver oxalate was adjusted to the ratio shown in Table 1 described later.

Organic solvent (c)
c1: 3-methoxy-3-methyl-1-butanol (manufactured by Tokyo Chemical Industry Co., Ltd.)
c2: Diethylene glycol monobutyl ether (Wako Pure Chemical Industries, Ltd.)

(2) Production of metal nanoparticles In a 50 mL glass centrifuge tube containing a magnetic stirrer, the amine compound (b) mixed solution is in an amount (0.9 g (Examples 3 and 5)) in the molar amount shown in Table 1. 1.8 g (Examples 1, 2 and 4), 3.6 g (Comparative Examples 1 and 2)) and the organic solvent (c) is added, the weight (1. 5 g (Examples 2 and 3 and Comparative Example 2) and 3.0 g (Examples 4 and 5)) were added and stirred for about 1 minute with a magnetic stirrer, and each composition used for the production (reaction) of metal nanoparticles. I adjusted things. After that, as shown in Table 1, 3.0 g of silver nitrate (a1) was added, stirred for about 10 minutes at room temperature, and then a hot stirrer equipped with an aluminum block that could be installed with a centrifuge tube (Koike Precision Equipment) It heated at 130 degreeC on the manufacturing company make HHE-19G-U). The reaction started in 10 to 15 minutes from the start of heating, and then finished in about 3 to 10 minutes. After cooling, the magnetic stirrer is taken out, 30 g of methanol is added and the mixture is stirred with a vortex mixer, and then centrifuged at 3000 rpm (about 1600 × G) for 1 minute with a centrifuge (CF7D2 manufactured by Hitachi Koki). The supernatant was removed. The steps of adding methanol, stirring, centrifuging, and removing the supernatant were repeated twice to collect each produced metal nanoparticle.
The composition of the composition used in each example and comparative example is shown in Table 1 below.

(3) Preparation of conductive ink The metal nanoparticles obtained in each reaction, after removing all the solvent by tilting the centrifuge tube, the solvent for converting to conductive ink (octane / butanol = 80/20 (Vol / Vol%)) Was charged in the same weight as the weight of the metal nanoparticles finely subtracted, and silver nanoparticles were dispersed to prepare a conductive ink.

(4) Measurement of average particle diameter of metal nanoparticles Using the obtained silver nanoparticle-dispersed ink and a spin coater (ASC-4000 manufactured by Actes Co., Ltd., 1500 rpm), a 400 nm thick film is formed on a PET film (Toray Lumirror U483). A thin film was prepared. The obtained metal thin film was observed with a scanning electron microscope (S-4500, manufactured by Hitachi High-Tech) without firing, and the particle shape of the surface was observed. The average particle diameter was calculated from the average value of 20 particles by measuring the long sides of the image particles. The results are shown in Table 1.

(5) Conductivity evaluation Using the conductive inks of Examples 1 to 5 and Comparative Examples 1 and 2 and a spin coater (ASC-4000 manufactured by Actes Co., Ltd., 1500 rpm) on a PET film (Toray Lumirror U483). A thin film having a thickness of 400 nm was prepared. The resistance value (without heat treatment) of the metal thin film obtained by spin coating for 3 days at room temperature and the resistance value (with heat treatment) of heat treatment at 70 ° C. for 1 hour immediately after spin coating were measured. Measurement was performed using a probe-type conductivity meter (Lorestar AX manufactured by Mitsubishi Chemical Analytech). The results are shown in Table 2.

  In Example 1, metal nanoparticles were prepared with (b) / (a1) = 0.8. The obtained metal nanoparticles and the conductive ink using the same were dark amber and the average particle size was 77.9 nm.

  Example 2 was the same as Example 1 except that the organic solvent (c) was added. After the organic solvent (c) was added, the metal compound and the amine compound were more uniformly dispersed in the composition as compared with Example 1. The average particle diameter of the obtained metal nanoparticles was 23.5 nm.

  Example 3 was the same as Example 2 except that (b) / (a1) = 0.4. Also in Example 3, the composition was uniformly dispersed, but the time from the start of heating to the start of the reaction was slightly longer than in Example 2. The average particle diameter of the obtained metal nanoparticles was 64.6 nm.

  Example 4 was the same as Example 2 except that (b) / (a1) = 0.4 and the amount of organic solvent (c) added was doubled. The time from the start of heating to the start of the reaction was longer than that of Example 2 and Example 3, and was about 15 minutes. The average particle diameter of the obtained metal nanoparticles was 53.7 nm.

  Example 5 was the same as Example 2 except that the organic solvent (c) was changed to diethylene glycol monobutyl ether. The composition was uniformly dispersed as in Examples 2-4. In addition, it took about 10 minutes from the start of heating to the start of the reaction. The average particle diameter of the obtained metal nanoparticles was 28.8 nm.

  Comparative Example 1 was the same as Example 1 except that (b) / (a1) = 1.6. The average particle diameter of the obtained metal nanoparticles was 16.4 nm, and metal nanoparticles having an average particle diameter of 20 nm or more were not obtained.

  Comparative Example 2 was the same as Example 2 except that (b) / (a1) = 1.6. The average particle diameter of the obtained metal nanoparticles was 18.7 nm, and metal nanoparticles having an average particle diameter of 20 nm or more were not obtained.

From Table 2, it can be seen that the resistance value tends to be lower as the average particle size of the metal nanoparticles is larger regardless of the presence or absence of heat treatment. This is because the coating of the amine compound (b) remains on the surface of the metal nanoparticle because the temperature is low at room temperature and heat treatment at 70 ° C., and the metal nanoparticle having a large particle diameter, that is, a specific surface area is small. However, it is considered that the resistance value was lowered because the remaining amount of the amine compound was small.
The conductivity of the metal nanoparticles of each example of the present invention was almost equal to or higher than the conductivity of the metal nanoparticles of the comparative example having an average particle diameter of less than 20 nm. In addition, since the metal nanoparticles of each example of the present invention have a relatively large average particle diameter, the amount of the protective layer is relatively small, and accordingly, the heat treatment time of the conductive ink or paste containing the metal nanoparticles is increased. It can be shortened or the heat treatment temperature can be lowered. That is, the metal nanoparticles of the present invention can reduce the heat treatment temperature or time of the conductive ink or paste while maintaining the high conductivity of the metal nanoparticles having an average particle diameter of less than 20 nm.

  The conductive ink prepared by using the metal nanoparticles obtained by the production method of the present invention exhibits high electrical conductivity by a short heat treatment, and thus is not limited by the heat resistance of the base material. It can be applied to various printing methods for a wide range of substrates such as polymer films. Specifically, it can be effectively used as a material for printed electronics used for electric circuit wiring and electrode formation. Furthermore, the metal nanoparticles obtained by the production method of the present invention can be effectively used in various fields such as conductive adhesives, electromagnetic wave absorbers, and light reflectors.

Claims (12)

  It is a manufacturing method of the metal nanoparticle which makes the composition containing a metal compound (a) and an amine compound (b) react, Comprising: Content of the amine compound (b) in a composition is contained in a metal compound (a) The method is characterized by being in the range of more than 0 mol and not more than 1 mol with respect to 1 mol of the metal atom.   The manufacturing method of Claim 1 in which a composition contains the organic solvent (c) which melt | dissolves 1g / L or more with respect to 20 degreeC water further.   The production method according to claim 2, wherein the organic solvent (c) contains a solvent having an ether bond and a hydroxyl group.   The production method according to claim 2 or 3, wherein the organic solvent (c) contains at least one solvent selected from the group consisting of glycol ethers and alcohols having an alkoxy group.   The production method according to claim 1, wherein the metal compound (a) is a metal oxalate salt.   The production method according to any one of claims 1 to 5, wherein the amine compound (b) is at least one selected from the group consisting of a primary amine and a diamine compound having a primary amine and a tertiary amine. .   The manufacturing method in any one of Claims 1-6 in which a composition contains a fatty acid (d) further.   The production method according to claim 7, wherein the content of the fatty acid in the composition is from 0.1 parts by weight to 15 parts by weight with respect to 1 part by weight of the metal compound (a).   The production method according to any one of claims 1 to 8, wherein the reaction is a thermal decomposition reaction at a temperature of 50 ° C or higher and 250 ° C or lower.   Metal nanoparticles having an average particle diameter of 20 nm to 200 nm obtained by the production method according to claim 1.   The electroconductive ink composition containing the metal nanoparticle obtained by the manufacturing method in any one of Claims 1-9, or an electroconductive paste.   The circuit wiring or electrode formed using the conductive ink composition of Claim 11, or a conductive paste.