JP6532862B2 - Silver nanoparticle-containing ink for intaglio offset printing and method for producing the same - Google Patents

Description

  The present invention relates to a silver nanoparticle-containing ink for intaglio offset printing and a method for producing the same. The present invention is also applied to a metal nanoparticle-containing ink for intaglio offset printing, which contains a metal other than silver, and a method for producing the same.

  Silver nanoparticles can be sintered even at low temperatures. Silver coating compositions containing silver nanoparticles have been used to form electrodes and conductive circuit patterns on a substrate in the manufacture of various electronic devices by utilizing this property. Silver nanoparticles are usually dispersed in an organic solvent. Silver nanoparticles have an average primary particle size of about several nm to several tens of nm, and usually the surface is coated with an organic stabilizer (protective agent). When the substrate is a plastic film or sheet, it is necessary to sinter the silver nanoparticles at a low temperature (eg, 200 ° C. or less) below the heat resistance temperature of the plastic substrate.

  In particular, not only heat-resistant polyimides already used as flexible printed wiring boards in recent years, but also various plastics such as PET (polyethylene terephthalate) and polypropylene, which are less heat resistant than polyimides but are easy to process and are inexpensive Attempts have also been made to form fine metal interconnections (eg, silver interconnections) for the above substrates. In the case of using a plastic substrate with low heat resistance, it is necessary to sinter the metal nanoparticles (eg, silver nanoparticles) at a lower temperature.

  For example, in JP-A-2008-214695, silver oxalate and oleylamine are reacted to form a complex compound containing at least silver, oleylamine and oxalate ion, and the formed complex compound is thermally decomposed to form silver. A method of producing silver ultrafine particles is disclosed which includes producing ultrafine particles (claim 1). Further, in the above method, when the silver oxalate and the oleylamine are reacted with a saturated aliphatic amine having 1 to 18 carbon atoms in total (claims 2 and 3), complex compounds can be easily formed, and ultrafine silver particles are obtained. It has been disclosed that the time required for the production of H. can be reduced, and furthermore, these amine-protected silver ultrafine particles can be produced in a higher yield (paragraph [0011]).

  In JP 2010-265543 A, a silver compound which is decomposed by heating to form metallic silver, a medium short chain alkylamine having a boiling point of 100 ° C. to 250 ° C., and a medium short chain alkyl diamine having a boiling point 100 ° C. to 250 ° C. And a step of preparing a complex compound containing the silver compound, the alkylamine and the alkyldiamine, and a second step of thermally decomposing the complex compound. (Claim 3, paragraphs [0061], [0062]).

  In JP 2012-162767 A, a mixture of an amine 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 obtain the metal compound and the amine. A method of producing coated metal fine particles is disclosed, which comprises a first step of forming a complex compound containing the following, and a second step of thermally decomposing the complex compound to form metal fine particles (claim 1). It is also disclosed that the coated silver fine particles can be dispersed in an organic solvent such as an alcohol solvent such as butanol, a nonpolar solvent such as octane, or a mixed solvent thereof (Paragraph [0079]).

  JP 2013-142172 A relates to a method for producing silver nanoparticles, which comprises an aliphatic hydrocarbon group and one amino group, and the total number of carbon atoms of the aliphatic hydrocarbon group is 6 or more. Aliphatic hydrocarbon monoamine (B) comprising an aliphatic hydrocarbon group and one amino group, wherein the total number of carbon atoms of the aliphatic hydrocarbon group is 5 or less, and an aliphatic hydrocarbon An amine mixture comprising an aliphatic hydrocarbon diamine (C) comprising a group and two amino groups, wherein the total number of carbon atoms in the aliphatic hydrocarbon group is 8 or less is prepared, and a silver compound and the amine mixture are prepared. And forming a complex compound containing the silver compound and the amine, and heating and thermally decomposing the complex compound to form a silver nanoparticle, and a method of producing a silver nanoparticle is disclosed. (Claim 1) . In addition, it is disclosed that a silver coating composition called a so-called silver ink can be produced by dispersing the obtained silver nanoparticles in a suitable organic solvent (dispersion medium) in a suspended state, and an organic solvent is disclosed. Aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane and the like; aromatic hydrocarbon solvents such as toluene, xylene, mesitylene and the like; methanol, ethanol, propanol Alcohol solvents such as n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol and the like are disclosed (paragraph [0085]).

  JP-A-2013-142173 discloses a method for producing silver nanoparticles, which comprises an aliphatic hydrocarbon group and one amino group, and the total number of carbon atoms of the aliphatic hydrocarbon group is 6 or more. A hydrocarbon monoamine (A) and an aliphatic hydrocarbon monoamine (B) consisting of an aliphatic hydrocarbon group and one amino group, wherein the total carbon number of the aliphatic hydrocarbon group is 5 or less, in a specific ratio Is prepared, and the silver compound and the amine mixed solution are mixed to form a complex compound including the silver compound and the amine, and the complex compound is thermally decomposed to obtain silver nano particles. A method of producing silver nanoparticles comprising forming particles is disclosed (Claim 1). Further, as in the case of the above-mentioned JP-A-2013-142172, a silver paint composition called a so-called silver ink is obtained by dispersing the obtained silver nanoparticles in an appropriate organic solvent (dispersion medium) in a suspended state. It is disclosed that it is possible to produce and similar organic solvents are disclosed (paragraph [0076]).

  WO 2014/024721 is a branched aliphatic hydrocarbon monoamine (comprised of a branched aliphatic hydrocarbon group and one amino group, and the carbon number of the branched aliphatic hydrocarbon group is 4 or more). An aliphatic amine containing at least D) and a silver compound are mixed to form a complex compound containing the silver compound and the amine, and the complex compound is thermally decomposed to form silver nanoparticles. , And a method of producing silver nanoparticles comprising the same.

JP-A-2010-55807 discloses, a conductive paste used in intaglio offset printing method using a silicone blanket composed of silicone rubber, a binder resin, conductive powder, and highly swellable solvent and low Rise Junsei solvent And a conductive paste containing a mixed solvent with the above (claim 1). Silver powder is mentioned as a conductive powder (paragraph [0033]). It is disclosed that the conductive powder preferably has a 50% cumulative diameter D ₅₀ of 0.05 μm or more and 10 μm or less, particularly 0.1 μm or more and 2 μm or less of the particle size distribution, and has a large particle size (paragraph [0034] ). JP 2010-55807 A does not disclose silver nanoparticles whose surface is coated with a protective agent containing an aliphatic hydrocarbon amine.

  JP-A-2010-90211 discloses a conductive ink composition containing conductive particles and an organic vehicle containing a resin composition and a solvent (claim 1). It is disclosed that the conductive particles are Ag particles (claim 10). The conductive ink composition is used to form an electrode by intaglio offset printing (paragraph [0001]). The conductive particles are disclosed to contain spherical conductive particles having an average particle diameter of 0.05 μm to 3 μm and flake-like conductive particles having an average flake diameter of 0.1 μm or more and less than 3 μm. (Paragraph [0014]). JP 2010-90211 A does not disclose silver nanoparticles whose surface is coated with a protective agent containing an aliphatic hydrocarbon amine.

JP 2008-214695 A JP, 2010-265543, A JP 2012-162767 A JP, 2013-142172, A JP, 2013-142173, A WO 2014/024721 JP, 2010-55807, A Unexamined-Japanese-Patent No. 2010-90211

  Silver nanoparticles have an average primary particle size of about several nm to several tens of nm, and are easily aggregated as compared with particles of micron (μm) size. Therefore, the reduction reaction of the silver compound (the thermal decomposition reaction in the above Patent Documents 1 to 6) such that the surface of the obtained silver nanoparticle is coated with the organic stabilizer (protective agent such as aliphatic amine or aliphatic carboxylic acid) ) Is carried out in the presence of organic stabilizers.

  On the other hand, silver nanoparticles are used as a silver paint composition (silver ink, silver paste) containing the particles in an organic solvent. In order to develop conductivity, it is necessary to remove the organic stabilizer covering the silver nanoparticles and sinter the silver particles at the time of baking after coating on the substrate. If the temperature of calcination is low, the organic stabilizer is less likely to be removed. If the degree of sintering of the silver particles is not sufficient, low resistance values can not be obtained. That is, although the organic stabilizer present on the surface of the silver nanoparticles contributes to the stabilization of the silver nanoparticles, it prevents the sintering of the silver nanoparticles (in particular, sintering at low temperature firing).

  When an aliphatic amine compound and / or an aliphatic carboxylic acid compound having a relatively long chain (for example, a carbon number of 8 or more) is used as the organic stabilizer, the distance between the individual silver nanoparticles is easily secured, Nanoparticles are easily stabilized. On the other hand, long-chain aliphatic amine compounds and / or aliphatic carboxylic acid compounds are difficult to remove if the temperature of calcination is low.

  Thus, there is a trade-off between the stabilization of silver nanoparticles and the development of low resistance value at low temperature firing.

  The electroconductive powder in Unexamined-Japanese-Patent No. 2010-55807 is a thing of large particle diameter, and it does not disclose about the silver nanoparticle by which the surface was coat | covered with the protective agent containing aliphatic hydrocarbon amine.

  The electroconductive particle in Unexamined-Japanese-Patent No. 2010-90211 is a thing of large particle diameter, and it does not disclose about the silver nanoparticle by which the surface was coat | covered with the protective agent containing aliphatic hydrocarbon amine.

  By the way, when using silver nanoparticle containing ink for intaglio offset printing, it is necessary to improve the transferability of silver ink from a blanket to a substrate. In intaglio offset printing, first, silver ink is filled in the concave part of the intaglio, and the silver ink filled in the concave part is transferred and received by the blanket (usually made of silicone rubber), and then the silver ink is transferred from the blanket to the substrate to be printed Transcribe. At this time, if the blanket absorbs and swells the solvent of the silver ink to a certain extent, thereby reducing the adhesion between the silver ink and the blanket surface, the transferability from the blanket to the substrate is improved.

  A silver nanoparticle-containing ink suitable for intaglio offset printing capable of sintering silver nanoparticles in low-temperature firing and in which silver nanoparticles are well dispersed in an organic solvent has not been developed so far.

  Therefore, an object of the present invention is to provide a silver nanoparticle-containing ink which exhibits excellent conductivity (low resistance value) by baking at a low temperature for a short time and which is suitable for intaglio offset printing, and a method for producing the same. It is in.

  The present inventors have found that the above object can be achieved by dispersing silver nanoparticles prepared by a so-called thermal decomposition method using a dispersion solvent containing a terpene solvent and a glycol ester solvent.

The present invention includes the following inventions.
(1) Silver nanoparticles coated on the surface with a protective agent containing an aliphatic hydrocarbon amine,
A silver nanoparticle-containing ink for intaglio offset printing, comprising a dispersion solvent containing a terpene solvent and a glycol ester solvent.

  (2) The silver nanoparticle-containing ink according to (1), wherein the dispersion solvent is contained in a range of 30% by weight or more and 60% by weight or less based on the ink.

  (3) The dispersion solvent contains the terpene solvent in a range of 20% by weight to 80% by weight, and the glycol ester solvent in a range of 20% by weight to 80% by weight based on the dispersion solvent. Silver nanoparticle containing ink as described in said (1) or (2) containing.

  (4) The silver nanoparticle-containing ink according to any one of the above (1) to (3), further comprising a cellulose-based resin as an additive.

(5) The aliphatic hydrocarbon amine comprises an aliphatic hydrocarbon monoamine (A) which comprises an aliphatic hydrocarbon group and one amino group, and the total number of carbon atoms of the aliphatic hydrocarbon group is 6 or more,
Furthermore, an aliphatic hydrocarbon monoamine (B) comprising an aliphatic hydrocarbon group and one amino group, and the total number of carbon atoms of the aliphatic hydrocarbon group is 5 or less, and an aliphatic hydrocarbon group and two amino groups And at least one of aliphatic hydrocarbon diamines (C) wherein the total number of carbon atoms of the aliphatic hydrocarbon group is 8 or less, and any one of the above (1) to (4) Silver nanoparticle-containing ink.

  (6) The aliphatic hydrocarbon monoamine (A) is a linear alkyl monoamine having a linear alkyl group having 6 to 12 carbon atoms, and a branched alkyl group having 6 to 16 carbon atoms. The silver nanoparticle-containing ink according to the above (5), which is at least one selected from the group consisting of branched alkyl monoamines.

  (7) The silver nanoparticle-containing ink according to (5) or (6) above, wherein the aliphatic hydrocarbon monoamine (B) is an alkyl monoamine having 2 to 5 carbon atoms.

  (8) The above aliphatic hydrocarbon diamine (C) is an alkylene diamine in which one of two amino groups is a primary amino group and the other is a tertiary amino group (5) The silver nanoparticle-containing ink according to any one of the above items (7) to (7).

  -The silver nanoparticle-containing ink according to any one of the above items, wherein the aliphatic hydrocarbon amine comprises the aliphatic hydrocarbon monoamine (A) and the aliphatic hydrocarbon monoamine (B). .

  The silver nanoparticle-containing ink according to any one of the above items, wherein the aliphatic hydrocarbon amine contains the aliphatic hydrocarbon monoamine (A) and the aliphatic hydrocarbon diamine (C). .

  The aliphatic hydrocarbon amine includes the aliphatic hydrocarbon monoamine (A), the aliphatic hydrocarbon monoamine (B), and the aliphatic hydrocarbon diamine (C). Silver nanoparticle-containing ink according to any of the above.

  The silver nanoparticle-containing ink according to any one of the above items, wherein the protective agent further contains an aliphatic carboxylic acid in addition to the aliphatic amine.

  The silver nanoparticle-containing ink according to any one of the above items, wherein the protective agent does not contain an aliphatic carboxylic acid.

  (9) The aliphatic hydrocarbon amine is used in an amount of 1 to 50 moles in total based on 1 mole of silver atoms of the silver nanoparticles, according to any one of the above (1) to (8) Silver nanoparticle-containing ink.

(10) A mixture of an aliphatic hydrocarbon amine and a silver compound to form a complex compound containing the silver compound and the amine,
The complex compound is heated and pyrolyzed to form silver nanoparticles,
The silver nanoparticles are dispersed in a dispersion solvent containing a terpene solvent and a glycol ester solvent.
And a method for producing a silver nanoparticle-containing ink for intaglio offset printing.

  (11) The method for producing a silver nanoparticle-containing ink according to (10), wherein the silver compound is silver oxalate.

The method for producing a silver nanoparticle-containing ink according to any one of the above items, wherein the aliphatic hydrocarbon amine is used in a total amount of 1 to 50 moles per 1 mole of silver atoms of the silver compound.
Silver oxalate molecules contain two silver atoms. When the silver compound is silver oxalate, the silver according to any one of the above items, wherein 2 to 100 moles of the aliphatic hydrocarbon amine as a total is used with respect to 1 mole of silver oxalate Method for producing nanoparticle-containing ink.

・ With a board,
The silver nanoparticle-containing ink according to any of the above items or the silver nanoparticle-containing ink produced by the method according to any of the items is applied onto the substrate by intaglio offset printing And a silver conductive layer formed by firing the formed coating layer,
Containing silver conductive material.
The silver conductive layer is patterned by intaglio offset printing.
The baking is performed at a temperature of 200 ° C. or less, for example 150 ° C. or less, preferably 120 ° C. or less, for 2 hours or less, for example 1 hour or less, preferably 30 minutes or less, more preferably 15 minutes or less. More specifically, it is carried out under the conditions of about 90 ° C. to 120 ° C., about 10 minutes to 15 minutes, for example, the conditions of 120 ° C. for 15 minutes.

A silver nanoparticle-containing ink according to any of the above items or a silver nanoparticle-containing ink produced by the method according to any of the items is applied onto a substrate by intaglio offset printing And forming a silver nanoparticle-containing coating layer, and then firing the coating layer to form a silver conductive layer.
The baking is performed at a temperature of 200 ° C. or less, for example 150 ° C. or less, preferably 120 ° C. or less, for 2 hours or less, for example 1 hour or less, preferably 30 minutes or less, more preferably 15 minutes or less. More specifically, it is carried out under the conditions of about 90 ° C. to 120 ° C., about 10 minutes to 15 minutes, for example, the conditions of 120 ° C. for 15 minutes.

  -Application by silver intaglio offset printing method of silver nanoparticle-containing ink according to any of the above items or silver nanoparticle-containing ink produced by the method according to any of the items, and baking Electronic device having a formed silver conductive layer. The electronic devices include various wiring boards, modules and the like.

Metal nanoparticles whose surface is coated with a protective agent containing an aliphatic hydrocarbon amine,
An ink containing metal nanoparticles for intaglio offset printing, comprising a dispersion solvent containing a terpene solvent and a glycol ester solvent.

An aliphatic hydrocarbon amine and a metal compound are mixed to form a complex compound containing the metal compound and the amine,
The complex compound is heated and pyrolyzed to form metal nanoparticles,
The metal nanoparticles are dispersed in a dispersion solvent containing a terpene solvent and a glycol ester solvent.
And a method for producing a metal nanoparticle-containing ink for intaglio offset printing.

  In the silver nanoparticle-containing ink of the present invention, the silver nanoparticles, the surfaces of which are coated with a protective agent containing an aliphatic hydrocarbon amine, are dispersed in a dispersion solvent containing a terpene solvent and a glycol ester solvent. Such a dispersion solvent improves the transferability of the silver ink from the blanket to the substrate when the silver nanoparticle-containing ink is used for intaglio offset printing. In intaglio offset printing, first, silver ink is filled in the concave portion of the intaglio, and the silver ink filled in the concave portion is transferred and received on a blanket (usually made of silicone rubber), and then the silver ink is transferred from the blanket to the substrate . At this time, it is considered that the blanket absorbs and swells the solvent of the silver ink to some extent, thereby reducing the adhesion between the silver ink and the blanket surface and improving the transferability from the blanket to the substrate. Thus, according to the present invention, a silver nanoparticle-containing ink suitable for intaglio offset printing applications is provided.

  Silver nanoparticles coated on the surface with a protective agent containing an aliphatic hydrocarbon amine are prepared by a so-called thermal decomposition method of a silver complex compound. In the present invention, as an aliphatic hydrocarbon amine compound functioning as a complexing agent and / or a protecting agent, an aliphatic hydrocarbon monoamine (A) having 6 or more carbons in total and an aliphatic hydrocarbon monoamine (B) having 5 or less carbons in total And at least one of an aliphatic hydrocarbon diamine (C) having a total number of carbon atoms of 8 or less, the surface of the formed silver nanoparticles is coated with these aliphatic amine compounds.

  Since the aliphatic hydrocarbon monoamine (B) and the aliphatic hydrocarbon diamine (C) have a short carbon chain length, in the case of baking at a low temperature of 200 ° C. or less, for example 150 ° C. or less, preferably 120 ° C. or less Also, it is easy to be removed from the surface of silver particles in a short time of 2 hours or less, for example, 1 hour or less, preferably 30 minutes or less. In addition, due to the presence of the monoamine (B) and / or the diamine (C), the amount of the aliphatic hydrocarbon monoamine (A) attached to the surface of the silver particle may be small. Therefore, even in the case of the baking at the low temperature, these aliphatic amine compounds are easily removed from the surface of the silver particles in the short time, and the sintering of the silver particles proceeds sufficiently.

  Thus, according to the present invention, a silver nanoparticle-containing ink suitable for intaglio offset printing applications in which excellent conductivity (low resistance value) is exhibited by firing at a low temperature for a short time, and a method for producing the same are provided. Be done.

  The present invention is also applicable to metal nanoparticle-containing inks containing metals other than silver, and methods for producing the same.

  According to the present invention, the conductive film and the conductive wiring can be formed by intaglio offset printing on various low heat resistant plastic substrates such as PET and polypropylene. The silver nanoparticle-containing ink of the present invention is suitable for the device application of various recent electronic devices.

  The silver nanoparticle-containing ink for intaglio offset printing of the present invention contains silver nanoparticles whose surface is coated with a protective agent containing an aliphatic hydrocarbon amine, and a dispersion solvent containing a terpene solvent and a glycol ester solvent.

The silver nanoparticle-containing ink for intaglio printing offset printing mixes an aliphatic hydrocarbon amine and a silver compound to form a complex compound including the silver compound and the amine.
The complex compound is heated and pyrolyzed to form silver nanoparticles,
The silver nanoparticles are dispersed in a dispersion solvent containing a terpene solvent and a glycol ester solvent.
Manufactured by Thus, the method of producing silver nanoparticles mainly includes the step of forming a complex compound and the step of thermally decomposing the complex compound, and the obtained silver nanoparticles are subjected to the dispersing step.

  As used herein, the term "nanoparticle" means that the primary particle size (average primary particle size) determined by scanning electron microscope (SEM) observation is less than 1000 nm. Also, the particle size is intended to be the size excluding the protective agent (stabilizer) present on the surface (that is, the size of silver itself). In the present invention, the silver nanoparticles have an average primary particle size of, for example, 0.5 nm to 100 nm, preferably 0.5 nm to 50 nm, more preferably 0.5 nm to 25 nm, and still more preferably 0.5 nm to 20 nm. There is.

  In the present invention, a silver compound which is easily decomposed by heating to generate metallic silver is used as the silver compound. As such a silver compound, silver formate such as silver formate, silver acetate, silver oxalate, silver malonate, silver benzoate, silver phthalate and the like; silver fluoride, silver chloride, silver bromide, silver iodide and the like Silver sulfate, silver nitrate, silver carbonate and the like can be used, but silver oxalate is preferably used from the viewpoint of easily forming metallic silver by decomposition and hardly generating impurities other than silver. Silver oxalate is advantageous in that it has a high silver content, does not require a reducing agent, metal silver is obtained as it is by thermal decomposition, and impurities derived from the reducing agent are less likely to remain.

  When producing metal nanoparticles containing metals other than silver, in place of the above-mentioned silver compounds, metal compounds which are easily decomposed by heating to produce a target metal are used. As such a metal compound, salts of metals corresponding to the above silver compounds, for example, metal carboxylates; metal halides; metal salt compounds such as metal sulfates, metal nitrates, metal carbonates and the like are used be able to. Among these, metal oxalate is preferably used from the viewpoint of easily generating a metal by decomposition and hardly generating an impurity other than a metal. Other metals include Al, Au, Pt, Pd, Cu, Co, Cr, In, Ni and the like.

  Moreover, in order to obtain a composite with silver, the above-described silver compound may be used in combination with another metal compound other than the above-described silver. Other metals include Al, Au, Pt, Pd, Cu, Co, Cr, In, Ni and the like. The silver composite is composed of silver and one or more other metals, and examples thereof include Au-Ag, Ag-Cu, Au-Ag-Cu, Au-Ag-Pd, and the like. Silver comprises at least 20% by weight, usually at least 50% by weight, for example at least 80% by weight, based on the total metal.

  In the present invention, the aliphatic hydrocarbon amine and the silver compound may be mixed in the absence of a solvent in the step of forming a complex compound, but they may be mixed in the presence of an alcohol solvent having 3 or more carbon atoms. It is preferable to form a complex compound containing an amine.

As said alcohol solvent, C3-C10 alcohol, Preferably C4-C6 alcohol can be used. 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 ℃), n- pen Tano Lumpur (bp: 136 ℃), n- hexanol (bp: 156 ℃), n- octanol (bp: 194 ℃), 2 -Octanol (bp: 174 ° C) and the like. Among these, n-butanol, isobutanol, sec-butanol, in consideration of the fact that the temperature of the thermal decomposition process of the complex compound to be performed later can be increased, the convenience in post-treatment after formation of silver nanoparticles, etc. Butanols and hexanols selected from tert-butanol are preferred. In particular, n-butanol and n-hexanol are preferred.

  The alcohol solvent is, for example, 120 parts by weight or more, preferably 130 parts by weight or more, and more preferably 150 parts by weight, based on 100 parts by weight of the silver compound, for sufficient stirring operation of the silver compound-alcohol slurry. It is preferable to use the above. The upper limit of the amount of the alcohol-based solvent is not particularly limited, and for example, 1000 parts by weight or less, preferably 800 parts by weight or less, more preferably 500 parts by weight or less with respect to 100 parts by weight of the silver compound. .

In the present invention, several forms can be taken to mix an aliphatic hydrocarbon amine and a silver compound in the presence of an alcohol solvent having 3 or more carbon atoms.
For example, first, a solid silver compound and an alcohol solvent are mixed to obtain a silver compound-alcohol slurry [slurry forming step], and then an aliphatic hydrocarbon amine is added to the obtained silver compound-alcohol slurry. You may add. The slurry represents a mixture in which a solid silver compound is dispersed in an alcohol solvent. A solid silver compound is charged into a reaction vessel, to which an alcohol solvent may be added to obtain a slurry.
Alternatively, an aliphatic hydrocarbon amine and an alcohol solvent may be charged in a reaction vessel, and a silver compound-alcohol slurry may be added thereto.

  In the present invention, as the aliphatic hydrocarbon amine which functions as a complexing agent and / or a protecting agent, it includes, for example, an aliphatic hydrocarbon monoamine (A) in which the total carbon number of hydrocarbon groups is 6 or more. Aliphatic hydrocarbon monoamine (B) comprising a hydrocarbon group and one amino group, wherein the total number of carbon atoms of the aliphatic hydrocarbon group is 5 or less, and comprising an aliphatic hydrocarbon group and two amino groups, At least one of the aliphatic hydrocarbon diamines (C) in which the total carbon number of the aliphatic hydrocarbon group is 8 or less may be used. Each of these components is usually used as an amine liquid mixture, but the mixing of the amine with the silver compound (or its alcohol slurry) does not necessarily have to be carried out using amines in a mixed state. The amines may be sequentially added to the silver compound (or an alcohol slurry thereof).

  As used herein, the term "aliphatic hydrocarbon monoamine" is a compound consisting of one to three monovalent aliphatic hydrocarbon groups and one amino group, as an established term. The "hydrocarbon group" is a group consisting only of carbon and hydrogen. However, as the aliphatic hydrocarbon monoamine (A) and the aliphatic hydrocarbon monoamine (B), hetero atoms such as an oxygen atom or a nitrogen atom (atoms other than carbon and hydrogen) may be used depending on the hydrocarbon group thereof. ) May have a substituent. This nitrogen atom does not constitute an amino group.

  In addition, “aliphatic hydrocarbon diamine” refers to a divalent aliphatic hydrocarbon group (alkylene group), two amino groups intervened by the aliphatic hydrocarbon group, and in some cases, hydrogen of the amino group. It is a compound which consists of an aliphatic hydrocarbon group (alkyl group) which substituted an atom. However, even if the aliphatic hydrocarbon diamine (C) has a substituent containing a hetero atom (an atom other than carbon and hydrogen) such as an oxygen atom or a nitrogen atom as necessary, in the hydrocarbon group thereof Good. This nitrogen atom does not constitute an amino group.

  The aliphatic hydrocarbon monoamine (A) having 6 or more carbon atoms in total has a high function as a protective agent (stabilizer) on the surface of silver particles formed due to its hydrocarbon chain.

  The aliphatic hydrocarbon monoamines (A) include primary amines, secondary amines, and tertiary amines. Examples of primary amines include hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecyl There may be mentioned saturated aliphatic hydrocarbon monoamines (that is, alkyl monoamines) having a linear aliphatic hydrocarbon group having 6 to 18 carbon atoms, such as amines. As a saturated aliphatic hydrocarbon monoamine, in addition to the above-mentioned linear aliphatic monoamine, is branched having 6 to 16 carbon atoms such as isohexylamine, 2-ethylhexylamine, tert-octylamine etc., preferably 6 to 8 carbon atoms Branched aliphatic hydrocarbon monoamines having an aliphatic hydrocarbon group. Moreover, cyclohexylamine is also mentioned. In addition, unsaturated aliphatic hydrocarbon monoamines (ie, alkenyl monoamines) such as oleylamine can be mentioned.

The secondary amine, as linear, N, N-dipropylamine, N, N-dibutylamine, N, N-dipentylamine, N, N-dihexylamine, N, N-di f heptylamine N, N-dioctylamine, N, N-dionylamine, N, N-didecylamine, N, N-diundecylamine, N, N-didodecylamine, N-methyl-N-propylamine, N-ethyl-N And dialkyl monoamines such as -propylamine and N-propyl-N-butylamine. Examples of tertiary amines include tributylamine and trihexylamine.

  Moreover, secondary amines, such as N, N- diisohexyl amine and N, N- di (2-ethyl hexyl) amine, are mentioned as a branched thing. In addition, tertiary amines such as triisohexylamine and tri (2-ethylhexyl) amine can be mentioned. In the case of N, N-di (2-ethylhexyl) amine, the carbon number of 2-ethylhexyl group is 8, but the total number of carbons contained in the amine compound is 16. In the case of tri (2-ethylhexyl) amine, the total number of carbons contained in the amine compound is 24.

  Among the monoamines (A), in the case of a linear chain, a saturated aliphatic hydrocarbon monoamine having 6 or more carbon atoms is preferable. By setting the number of carbon atoms to 6 or more, when an amino group is adsorbed on the surface of silver particles, a space from other silver particles can be secured, so the effect of preventing aggregation of silver particles is improved. The upper limit of the number of carbon atoms is not particularly limited, but in consideration of easy availability, easy removal at the time of firing, etc., saturated aliphatic monoamines having up to 18 carbon atoms are usually preferred. In particular, alkyl monoamines having 6 to 12 carbon atoms such as hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine and the like are preferably used. Among the linear aliphatic hydrocarbon monoamines, only one type may be used, or two or more types may be used in combination.

  In addition, when a branched aliphatic hydrocarbon monoamine compound is used, compared to the case where a linear aliphatic hydrocarbon monoamine compound having the same carbon number is used, the steric factor of the branched aliphatic hydrocarbon group causes a silver particle surface to be obtained. With a lower amount of adhesion of, it is possible to cover a larger area of the silver particle surface. Thus, with less deposition on the silver particle surface, adequate stabilization of the silver nanoparticles is obtained. Since the amount of protective agent (organic stabilizer) to be removed at the time of firing is small, even in the case of firing at a low temperature of 200 ° C. or less, the organic stabilizer can be efficiently removed, and sintering of silver particles proceeds sufficiently Do.

  Among the above branched aliphatic hydrocarbon monoamines, branched alkyl monoamine compounds having 5 to 6 carbon atoms in the main chain, such as isohexylamine and 2-ethylhexylamine, are preferable. When the carbon number of the main chain is 5 to 6, appropriate stabilization of silver nanoparticles is easily obtained. Further, from the viewpoint of the steric factor of the branched aliphatic group, it is effective that the second carbon atom from the N atom side is branched like 2-ethylhexylamine. As said branched aliphatic monoamine, only 1 type may be used and it may be used combining 2 or more types.

  In the present invention, as the aliphatic hydrocarbon monoamine (A), the linear aliphatic hydrocarbon monoamine and the branched aliphatic hydrocarbon monoamine may be used in combination to obtain their respective advantages.

  Aliphatic hydrocarbon monoamines (B) having 5 or less carbons in total have a short carbon chain length compared to aliphatic monoamines (A) having 6 or more carbons in total, and thus have a low function as a protective agent (stabilizer) per se It is considered that the polarity is high compared to the aliphatic monoamine (A), and the coordination ability of the silver compound to silver is high, and therefore, it is considered to be effective in promoting the complex formation. In addition, because the carbon chain length is short, it can be removed from the surface of silver particles in a short time of 30 minutes or less or 20 minutes or less, for example, even at low temperature baking of 120 ° C. or less or about 100 ° C. or less It is effective for low temperature firing of silver nanoparticles.

  Examples of the aliphatic hydrocarbon monoamine (B) include ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, isopentylamine, tert-pentylamine and the like A C2-C5 saturated aliphatic hydrocarbon monoamine (namely, alkyl monoamine) is mentioned. Moreover, dialkyl monoamines, such as N, N- dimethylamine and N, N-diethylamine, are mentioned.

  Among these, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, isopentylamine, tert-pentylamine and the like are preferable, and the above-mentioned butylamines are particularly preferable. Among the aliphatic hydrocarbon monoamines (B), only one type may be used, or two or more types may be used in combination.

  Aliphatic hydrocarbon diamine (C) having a total number of carbon atoms of 8 or less has high ability to coordinate silver to silver and is effective in promoting complex formation. Aliphatic hydrocarbon diamines are generally more polar than aliphatic hydrocarbon monoamines and have a higher ability to coordinate silver compounds with silver. Further, the aliphatic hydrocarbon diamine (C) has an effect of promoting thermal decomposition at a lower temperature and in a short time in the thermal decomposition step of the complex compound, and silver nanoparticles can be produced more efficiently. . Furthermore, since the protective film of the silver particles containing the aliphatic diamine (C) has high polarity, the dispersion stability of the silver particles in the dispersion medium containing the highly polar solvent is improved. Furthermore, since the aliphatic diamine (C) has a short carbon chain length, the surface of silver particles can be reduced for a short time of 30 minutes or less or 20 minutes or less even at low temperature firing of 120 ° C. or less or about 100 ° C. or less. Since it can be removed from the solution, it is effective for low temperature and short time firing of the obtained silver nanoparticles.

  Examples of the aliphatic hydrocarbon diamine (C) include, but are not limited to, ethylenediamine, N, N-dimethylethylenediamine, N, N'-dimethylethylenediamine, N, N-diethylethylenediamine, N, N'-diethylethylenediamine, 1 , 3-propanediamine, 2,2-dimethyl-1,3-propanediamine, N, N-dimethyl-1,3-propanediamine, N, N'-dimethyl-1,3-propanediamine, N, N- Diethyl-1,3-propanediamine, 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, 5-pentanediamine, 1,5-diamino-2-methylpentane, 1,6-hexanediamine, N, N-dimethyl-1,6-hexanediamine, N, N'-dimethyl-1,6-hexanediamine 1,7-heptanediamine, 1,8-octanediamine and the like. Each of these is an alkylene diamine having a total of 8 or less carbon atoms in which at least one of two amino groups is a primary amino group or a secondary amino group, and the coordination ability of the silver compound to silver is high. It is effective in promoting complex formation.

Among these, N, N-dimethylethylenediamine, N, N-diethylethylenediamine, N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, N, N-dimethylethylene One of two amino groups such as -1,4-butanediamine, N, N-diethyl-1,4-butanediamine, N, N-dimethyl-1,6-hexanediamine is a primary amino group ( Alkylenediamines having a total number of carbon atoms of 8 or less, which is -NH ₂ ) and the other one is a tertiary amino group (-NR ¹ R ² ), are preferred. Preferred alkylene diamines are represented by the following structural formula.

R ¹ R ² N-R-NH ₂
Here, R represents a divalent alkylene group, R ¹ and R ² may be the same or different, and represent an alkyl group, provided that the total number of carbon atoms of R, R ¹ and R ² is 8 It is below. The alkylene group usually does not contain hetero atoms (atoms other than carbon and hydrogen) such as oxygen atom or nitrogen atom, but may have a substituent containing the hetero atom as needed. The alkyl group usually does not contain a hetero atom such as an oxygen atom or a nitrogen atom, but may have a substituent containing the hetero atom as required.

  When one of the two amino groups is a primary amino group, the coordination ability of the silver compound to silver is increased, which is advantageous for complex formation, and the other one is a tertiary amino group. Since the tertiary amino group has a poor ability to coordinate to a silver atom, the complex to be formed is prevented from becoming a complex network structure. When the complex has a complex network structure, a high temperature may be required for the thermal decomposition process of the complex. Further, among these, from the viewpoint of being able to be removed from the surface of silver particles in a short time even at low temperature firing, diamines having 6 or less carbon atoms in total are preferable, and diamines having 5 or less carbon atoms in total are more preferable. Among the aliphatic hydrocarbon diamines (C), only one type may be used, or two or more types may be used in combination.

In the present invention, the aliphatic hydrocarbon monoamine (A) having 6 or more carbon atoms in total, the aliphatic hydrocarbon monoamine (B) having 5 or less carbon atoms in total, and the aliphatic hydrocarbon diamine (C) having 8 or less carbon atoms in total The use ratio with either one or both is not particularly limited, but, for example, based on the total amines [(A) + (B) + (C)], for example,
The said aliphatic monoamine (A): 5 mol%-65 mol%
The total amount of the aliphatic monoamine (B) and the aliphatic diamine (C): 35 mol% to 95 mol%
You should do it. By setting the content of the aliphatic monoamine (A) to 5% by mole to 65% by mole, the carbon chain of the component (A) can easily provide a protective stabilizing function of the surface of the silver particles to be produced. When the content of the component (A) is less than 5 mol%, the expression of the protective stabilizing function may be weak. On the other hand, when the content of the component (A) exceeds 65 mol%, the protective stabilizing function is sufficient, but the component (A) becomes difficult to be removed by low-temperature firing. When the branched aliphatic monoamine is used as the component (A), the content of the aliphatic monoamine (A) is 5% by mole to 65% by mole.
10 to 50% by mole of said branched aliphatic monoamine
You should do it.

In the case of using the aliphatic monoamine (A), and both the aliphatic monoamine (B) and the aliphatic diamine (C), the ratio of use thereof is not particularly limited, but the total amines For example, with reference to [(A) + (B) + (C)],
Aliphatic monoamine (A): 5 mol% to 65 mol%
Aliphatic monoamine (B): 5 mol% to 70 mol%
Said aliphatic diamine (C): 5 mol% to 50 mol%
You should do it. When the branched aliphatic monoamine is used as the component (A), the content of the aliphatic monoamine (A) is 5% by mole to 65% by mole.
10 to 50% by mole of said branched aliphatic monoamine
You should do it.

  In this case, the lower limit of the content of the component (A) is preferably 10 mol% or more, and more preferably 20 mol% or more. About the upper limit of content of the said (A) component, 65 mol% or less is preferable, and 60 mol% or less is more preferable.

  By setting the content of the aliphatic monoamine (B) to 5 mol% to 70 mol%, the complex formation promoting effect is easily obtained, and it can contribute to low temperature and short time baking by itself, and further, at the time of baking The effect of helping to remove the aliphatic diamine (C) from the surface of silver particles is easily obtained. When the content of the component (B) is less than 5 mol%, the complex formation promoting effect may be weak, or the component (C) may not be easily removed from the surface of silver particles at the time of firing. On the other hand, when the content of the component (B) exceeds 70 mol%, although the complex formation promoting effect is obtained, the content of the aliphatic monoamine (A) becomes relatively small, and silver particles formed It is difficult to obtain surface protection stabilization. The lower limit of the content of the component (B) is preferably 10 mol% or more, more preferably 15 mol% or more. About the upper limit of content of the said (B) component, 65 mol% or less is preferable, and 60 mol% or less is more preferable.

  By setting the content of the aliphatic diamine (C) to 5 mol% to 50 mol%, the complex formation promoting effect and the thermal decomposition promoting effect of the complex are easily obtained, and the aliphatic diamine (C) is contained. Since the protective coating of silver particles has high polarity, the dispersion stability of silver particles in a dispersion medium containing a highly polar solvent is improved. When the content of the component (C) is less than 5 mol%, the complex formation promoting effect and the thermal decomposition promoting effect of the complex may be weak. On the other hand, when the content of the component (C) exceeds 50 mol%, the complex formation promoting effect and the thermal decomposition promoting effect of the complex can be obtained, but the content of the aliphatic monoamine (A) becomes relatively small. It is difficult to obtain protection and stabilization of the surface of the silver particles to be formed. The lower limit of the content of the component (C) is preferably 5 mol% or more, more preferably 10 mol% or more. About the upper limit of content of the said (C) component, 45 mol% or less is preferable, and 40 mol% or less is more preferable.

In the case of using the aliphatic monoamine (A) and the aliphatic monoamine (B) (without using the aliphatic diamine (C)), the use ratio thereof is not particularly limited. In consideration of the action, for example, based on the total amines [(A) + (B)], for example,
Aliphatic monoamine (A): 5 mol% to 65 mol%
The said aliphatic monoamine (B): 35 mol%-95 mol%
You should do it. When the branched aliphatic monoamine is used as the component (A), the content of the aliphatic monoamine (A) is 5% by mole to 65% by mole.
10 to 50% by mole of said branched aliphatic monoamine
You should do it.

In the case of using the aliphatic monoamine (A) and the aliphatic diamine (C) (without using the aliphatic monoamine (B)), the use ratio thereof is not particularly limited. In consideration of the action, for example, based on the total amines [(A) + (C)], for example,
Aliphatic monoamine (A): 5 mol% to 65 mol%
Said aliphatic diamine (C): 35 mol% to 95 mol%
You should do it. When the branched aliphatic monoamine is used as the component (A), the content of the aliphatic monoamine (A) is 5% by mole to 65% by mole.
10 to 50% by mole of said branched aliphatic monoamine
You should do it.

  The above-mentioned use ratio of the above-mentioned aliphatic monoamine (A), the above-mentioned aliphatic monoamine (B) and / or the above-mentioned aliphatic diamine (C) is all examples, and various modifications are possible.

  In the present invention, when the aliphatic monoamine (B) and / or the aliphatic diamine (C) having high coordination ability to silver of the silver compound are used, the total number of carbon atoms is 6 depending on the ratio of use thereof. The adhesion amount of the above aliphatic monoamine (A) on the surface of silver particles may be small. Therefore, these aliphatic amine compounds are easily removed from the surface of the silver particles even in the case of the above-mentioned baking at a low temperature for a short time, and the sintering of the silver particles proceeds sufficiently.

  In the present invention, the total amount of the aliphatic hydrocarbon amine [eg, (A), (B) and / or (C)] is not particularly limited, but relative to 1 mole of silver atoms of the silver compound as a raw material. And about 1 to 50 moles. When the total amount of the amine component [(A), (B) and / or (C)] is less than 1 mol with respect to 1 mol of the silver atom, the complex compound is converted to a complex compound in the production step. In the subsequent thermal decomposition step, the uniformity of the silver particles may be impaired to cause enlargement of the particles, or the silver compound may remain without being thermally decomposed. On the other hand, it is considered that no merit is obtained even if the total amount of the amine component [((A), (B) and / or (C)] exceeds about 50 moles with respect to 1 mole of the silver atom. In order to prepare a dispersion of silver nanoparticles substantially in the absence of a solvent, the total amount of the amine components may be, for example, about 2 moles or more, and the total amount of the amine components may be about 2 to 50 moles. The lower limit of the total amount of the amine components is preferably 2 mol or more per 1 mol of silver atoms of the silver compound. The molar ratio is more preferable, and the silver oxalate molecule contains two silver atoms.

  In the present invention, an aliphatic carboxylic acid (D) may be further used as a stabilizer in order to further improve the dispersibility of silver nanoparticles in a dispersion medium. The aliphatic carboxylic acid (D) may be used together with the amines, and may be contained in the amine mixture. Use of the aliphatic carboxylic acid (D) may improve the stability of silver nanoparticles, particularly in the state of a paint dispersed in an organic solvent.

  As the aliphatic carboxylic acid (D), 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.

Among these, C8-C18 saturated or unsaturated aliphatic monocarboxylic acid is 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 (D), only one type may be used, or two or more types may be used in combination.

  When used, the aliphatic carboxylic acid (D) may be used, for example, about 0.05 to 10 moles, preferably 0.1 to 5 moles, relative to 1 mole of silver atoms of the silver compound as a raw material. More preferably, 0.5 to 2 moles may be used. When the amount of the component (D) is less than 0.05 mol with respect to 1 mol of the silver atom, the effect of improving the stability in the dispersed state by the addition of the component (D) is weak. On the other hand, when the amount of the component (D) reaches 10 moles, the effect of improving the stability in the dispersed state is saturated, and the removal of the component (D) in low-temperature firing becomes difficult. However, in consideration of the removal of the component (D) at low temperature firing, the aliphatic carboxylic acid (D) may not be used.

  In the present invention, generally, a mixed solution containing each aliphatic hydrocarbon amine component to be used; for example, any of the aliphatic monoamine (A), and any of the aliphatic monoamine (B) and the aliphatic diamine (C) Prepare an amine mixture containing either or both of them [Step of preparing amine mixture].

  The amine mixture liquid can be prepared by stirring each amine (A), (B) and / or (C) component, and the above-mentioned carboxylic acid (D) component when used, at a predetermined ratio at room temperature. .

  An aliphatic hydrocarbon amine mixed solution containing each amine component is added to the silver compound (or an alcohol slurry thereof) to form a complex compound containing the silver compound and the amine [a complex compound forming step]. Each amine component may be added to the silver compound (or its alcohol slurry) sequentially, not as a mixed solution.

  When producing metal nanoparticles containing metals other than silver, metal compounds containing the target metal (or alcohol slurry thereof) are used in place of the silver compounds (or the alcohol slurry thereof) described above.

  A silver compound (or its alcohol slurry) or a metal compound (or its alcohol slurry) is mixed with a predetermined amount of an amine mixed solution. The mixing may be performed at normal temperature. By "normal temperature" is intended 5-40 ° C depending on the ambient temperature. For example, 5 to 35 ° C. (JIS Z 8703), 10 to 35 ° C., 20 to 30 ° C. are intended. It may be at normal room temperature (e.g., in the range of 15 to 30 <0> C). Since mixing at this time is stirring, or coordination reaction of amines to a silver compound (or metal compound) is accompanied by heat generation, for example, about 5 to 15 ° C. so as to become the above temperature range. It may be carried out while appropriately cooling and stirring. When mixing of the silver compound and the amine liquid mixture is performed in the presence of an alcohol having 3 or more carbon atoms, stirring and cooling can be performed well. The excess of alcohol and amines plays the role of reaction medium.

  In the thermal decomposition method of a silver amine complex, conventionally, a liquid aliphatic amine component was first charged in a reaction vessel, and a powdery silver compound (silver oxalate) was charged therein. The liquid aliphatic amine component is a flammable substance, and there is a danger in introducing powdery silver compounds into it. That is, there is a risk of ignition due to static electricity due to the introduction of powdery silver compounds. In addition, due to the addition of powdery silver compounds, there is a risk that the complex formation reaction will proceed locally and the exothermic reaction will be exploded. Such danger can be avoided if the silver compound and the amine mixture are mixed in the presence of the alcohol. Therefore, it is safe also in scaled up industrial manufacture.

  Since the complex compound to be formed generally exhibits a color according to its constituent components, the end point of the complex compound formation reaction can be detected by detecting the end of the color change of the reaction mixture by an appropriate spectroscopy or the like. . In addition, although the complex compound formed by silver oxalate is generally colorless (observed as white by visual observation), also in such a case, based on the change in form of the reaction mixture such as the change in viscosity, the complex compound is The generation state can be detected. For example, the time of the reaction for producing a complex compound is about 30 minutes to 3 hours. In this way, a silver-amine complex (or metal-amine complex) is obtained in a medium based on alcohol and amines.

  Next, the obtained complex compound is heated and thermally decomposed to form silver nanoparticles [pyrolysis process of the complex compound]. When a metal compound containing another metal other than silver is used, a target metal nanoparticle is formed. Silver nanoparticles (metal nanoparticles) are formed without using a reducing agent. However, if necessary, an appropriate reducing agent may be used as long as the effects of the present invention are not inhibited.

  In such a metal amine complex decomposition method, in general, amines control the manner in which atomic metals formed by the decomposition of metal compounds aggregate to form microparticles, and on the surface of the formed metal microparticles. By forming a film, it plays a role of preventing reaggregation between particles. That is, by heating the complex compound of the metal compound and the amine, the metal compound is thermally decomposed to form an atomic metal while maintaining the coordination bond of the amine to the metal atom, and then the amine coordinates These metal atoms are believed to aggregate to form metal nanoparticles coated with an amine protective film.

  The thermal decomposition in this case is preferably performed while stirring the complex compound in a reaction medium mainly composed of an alcohol (if used) and an amine. The thermal decomposition is preferably performed in the temperature range in which the coated silver nanoparticles (or coated metal nanoparticles) are formed, but from the viewpoint of preventing the detachment of the amine from the silver particle surface (or the metal particle surface), the above temperature range It is preferable to carry out at a temperature as low as possible. In the case of a complex compound of silver oxalate, it may be, for example, about 80 ° C. to 120 ° C., preferably about 95 ° C. to 115 ° C., and more specifically about 100 ° C. to 110 ° C. In the case of a complex compound of silver oxalate, heating occurs at about 100 ° C. to cause decomposition and reduction of silver ions, whereby coated silver nanoparticles can be obtained. In general, thermal decomposition of silver oxalate itself occurs at about 200 ° C., but the reason why the thermal decomposition temperature is lowered by about 100 ° C. by forming a silver oxalate-amine complex compound is not clear. When the complex compound of silver oxalate and amine is formed, it is presumed that the coordination polymer structure formed by pure silver oxalate is broken.

  The thermal decomposition of the complex compound is preferably performed in an inert gas atmosphere such as argon, but thermal decomposition can also be performed in the atmosphere.

  The thermal decomposition of the complex compound gives a suspension exhibiting a blue gloss. From this suspension, removal operation of excess amine etc., for example, sedimentation of silver nanoparticles (or metal nanoparticles), decantation with suitable solvent (water or organic solvent) As a result, stable coated silver nanoparticles (or coated metal nanoparticles) can be obtained [post-treatment step of silver nanoparticles]. After the washing operation, if it is dried, a powder of the desired stable coated silver nanoparticles (or coated metal nanoparticles) is obtained. However, wet silver nanoparticles may be subjected to the preparation of silver nanoparticle-containing inks.

  Water or an organic solvent is used for the decantation / washing operation. Examples of the organic solvent include aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane and tetradecane; alicyclic hydrocarbon solvents such as cyclohexane; toluene, xylene, mesitylene and the like Aromatic hydrocarbon solvents such as: alcohol solvents such as methanol, ethanol, propanol, butanol and the like; acetonitrile; and mixed solvents thereof may be used.

  Since a reducing agent may not be used in the step of forming silver nanoparticles of the present invention, there is no by-product derived from the reducing agent, separation of coated silver nanoparticles from the reaction system is simple, and high purity coating Silver nanoparticles are obtained. However, if necessary, an appropriate reducing agent may be used as long as the effects of the present invention are not inhibited.

  In this way, the surface is coated with the protective agent used to form silver nanoparticles. The protective agent includes, for example, the aliphatic monoamine (A), and further includes any one or both of the aliphatic monoamine (B) and the aliphatic diamine (C), and is further used. Contains the carboxylic acid (D). Their content in the protective agent is equivalent to their use in the amine mixture. The same applies to metal nanoparticles.

  Next, the silver nanoparticles formed as described above are dispersed in a dispersion solvent (dispersion medium) containing a terpene solvent and a glycol ester solvent to prepare a silver nanoparticle-containing ink.

  As the glycol ester solvents, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate (PMA) And glycol monoesters such as 1-methoxy-2-propyl acetate) and dipropylene glycol monomethyl ether acetate). As the glycol ester-based solvent, only one type may be used, or two or more types may be used in combination.

  The glycol ester solvent has a property of penetrating to a silicone blanket. When the solvent infiltrates into the blanket, the blanket-ink interface is dried to reduce the adhesion between the ink and the blanket, which has the effect of improving the transferability of the ink from the blanket to the substrate. The glycol ester solvent also has the function of dissolving a cellulose resin as a viscosity modifier described later.

  Examples of the terpene solvents include terpene six-membered ring compounds. The terpene series six-membered ring compounds include α-pinene (bp: 155 to 156 ° C.), β-pinene (bp: 164 to 166 ° C.), limonene (bp: 175.5 to 176 ° C., 763 mmHg ° C.), α- Monocyclics such as terpinene (bp: 173.5 to 174.8 ° C., 755 mmHg), β-terpinene (bp: 173 to 174 ° C.), γ-terpinene (bp: 183 ° C.), terpinolene (bp: 186 ° C.) Monoterpenes are exemplified. As a commercially available thing, terpineol C and dihydro terpineol (all are Nippon terpene company make) are illustrated. As the terpene solvent, only one type may be used, or two or more types may be used in combination.

  The terpene solvents generally have high viscosity. For example, in the case of terpineol C, it has a viscosity of 54 mPa · s. Since the viscosity of the organic solvent other than the terpene type is about 10 mPa · s, when the terpene type solvent is used, the viscosity of the ink can be raised (adjusted) to a desired viscosity. When only the glycol ester solvent is used as the dispersion solvent, the silicone blanket may be excessively swollen, and the transferability of the ink to the substrate may be impaired. From this point of view, the terpene solvent is used to obtain an appropriate transferability improvement effect. In addition, the terpene solvent has an effect of dissolving a cellulose resin as a viscosity adjusting agent described later.

  The dispersion solvent contains, for example, the terpene solvent in the range of 20% by weight to 80% by weight and the glycol ester solvent in the range of 20% by weight to 80% by weight based on the dispersion solvent. . If the amount of the glycol ester solvent is less than 20% by weight, the amount of the solvent which penetrates into the blanket is small, and it is difficult to obtain the drying of the blanket-ink interface as described above. It tends to be difficult to obtain transfer improvement. On the other hand, when the amount of the glycol ester solvent exceeds 80% by weight, the amount of the solvent infiltrated into the blanket increases, which causes the blanket to swell excessively, and the transferability of the ink onto the substrate tends to be impaired. is there. When the amount of the glycol ester solvent is less than 20% by weight, the amount of the terpene solvent exceeds 80% by weight although it depends on the amount of the other dispersion solvent. When the amount of the glycol ester-based solvent exceeds 80% by weight, the amount of the terpene-based solvent is less than 20% by weight although it depends on the amount of the other dispersion solvent.

  The dispersion solvent preferably contains the terpene solvent in the range of 25% by weight to 75% by weight, and the glycol ester solvent in the range of 25% by weight to 75% by weight based on the dispersion solvent. Including.

  In the present invention, the silver nanoparticle-containing ink may further contain an alcohol solvent. The alcohol solvent is not particularly limited, and an aliphatic alcohol selected from linear alcohols, branched alcohols, and alcohols having a cyclic structure can be used. For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-pentanol, n-hexanol, 2-ethylhexanol, n-heptanol, n-octanol, n -Linear or branched aliphatic alcohols such as nonanol, n-decanol, undecanol, dodecanol and the like; cyclic (or containing a cyclic structure such as cyclopentanol, cyclohexanol, cyclohexane methanol and the like ) Aliphatic alcohol and the like. The alcohol solvent is suitably a saturated compound having no unsaturated bond. As said alcohol, only 1 type may be used and it may be used combining 2 or more types.

  The alcohol-based solvent is used for purification (solid-liquid separation operation in centrifugation) of silver nanoparticles derived from those used as a reaction solvent for complex formation and / or performed as a post-treatment step after thermal decomposition reaction It originates in things. The alcohol solvent contains about 10 wt% of the silver nanoparticle wet powder according to the result of the thermobalance. About 5-10 wt% of the total weight of the silver nanoparticle-containing ink is contained.

  In the present invention, the total amount of the dispersion solvent is, for example, 30% by weight or more and 60% by weight or less, preferably 30% by weight or more and 50% by weight or less, more preferably 30% by weight or more and 40% by weight based on the ink. It is included in the range of% or less. From the viewpoint of intaglio offset printing application, if the amount of the dispersion solvent is less than 30% by weight, the amount of the solvent may be small and transfer during printing may not be favorably performed. On the other hand, when the amount of the dispersion solvent exceeds 60% by weight, the amount of solvent is large, fine line printing may not be favorably performed, and low temperature firing may not be favorably performed.

  In the present invention, other dispersion solvents may be used in combination as long as the purpose is not impaired. Other dispersion solvents include aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane and tetradecane; alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane and decalin; toluene And aromatic hydrocarbon solvents such as xylene and mesitylene.

  In the present invention, the silver nanoparticle-containing ink may further contain a cellulose-based resin as an additive. The cellulose-based resin is not particularly limited, and examples thereof include ethyl cellulose and hydroxyethyl cellulose. As a commercial item of ethyl cellulose, the Etcel (ETHOCEL (registered trademark, Nisshin Kasei) series etc. are mentioned. By adding a cellulose-based resin, the viscosity of the silver nanoparticle-containing ink can be increased, and the printability can be improved. The amount of the cellulose-based resin added is, for example, 0.1% by weight or more and 10% by weight or less, preferably 2% by weight or more and 5% by weight or less, based on the ink. With such addition amounts, it is possible to perform appropriate viscosity adjustment of the ink.

  The viscosity of the silver nanoparticle-containing ink is, for example, in the range of 0.1 Pa · s to 30 Pa · s, preferably 5 Pa · s to 25 Pa · s, under environmental temperature conditions at the time of printing, in consideration of intaglio offset printing applications. It is the following range. If the viscosity of the ink is less than 0.1 Pa · s, the flowability of the ink is too high, which may cause problems in receiving the ink from the intaglio to the blanket and in transferring the ink from the blanket to the substrate to be printed. is there. On the other hand, when the viscosity of the ink exceeds 30 Pa · s, the flowability of the ink is too low, and the fillability of the intaglio into the concave portion becomes worse. If the filling property to the concave portion is deteriorated, the accuracy of the pattern transferred onto the substrate is lowered, and a defect such as a break of a thin line occurs.

  Suspension by mixing and stirring the powder of the coated silver nanoparticles in the dry or wet state obtained in the post-treatment step of the silver nanoparticles, the dispersion solvent described above, and the cellulose resin when used An ink (or paste) containing silver nanoparticles in the state can be prepared. The silver nanoparticles may be contained in the silver nanoparticle-containing ink in a proportion of, for example, 10% by weight or more, or 25% by weight or more, preferably 30% by weight or more, depending on the purpose of use. As an upper limit of the content of the silver nanoparticles, 80% by weight or less is a standard. The mixing and dispersion of the powder of the coated silver nanoparticles, the dispersion solvent, and the cellulose resin may be performed once or several times.

  The silver nanoparticle-containing ink obtained by the present invention is excellent in stability. The silver ink, for example, at a silver concentration of 50% by weight, is stable without causing a viscosity increase when stored at 5 ° C. under refrigeration for a period of one month or more.

  The prepared silver nanoparticle-containing ink is applied onto a substrate by intaglio offset printing and then fired.

  A patterned silver ink coating layer is obtained by intaglio offset printing, and the patterned silver conductive layer is obtained by baking the silver ink coating layer.

  In the intaglio offset printing, first, silver ink is filled in the concave portion of the intaglio plate, the silver ink filled in the concave portion is transferred and received onto a blanket usually made of silicone rubber, and then the silver ink is transferred from the blanket to the substrate. In the silver ink of the present invention, a mixed solvent containing a terpene solvent and a glycol ester solvent as a dispersion solvent is used. The mixed solvent infiltrates the blanket and swells the blanket. Depending on the amount of solvent infiltrated into the blanket, the concentration of the silver ink held on the blanket surface increases, that is, the drying progresses. Thereby, the adhesion between the silver ink on the blanket surface and the blanket is reduced, and the transferability of the silver ink from the blanket to the substrate is improved.

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, the firing of a short time, in order to complete the sintering of the silver, 60 ° C. or higher 200 ° C. or less, for example 80 ° C. or higher 0.99 ° C. or less, preferably be carried out at 90 ° C. than the 120 ° C. temperature below Good. The baking time may be appropriately determined in consideration of the coated amount of silver ink, baking temperature, etc., for example, within several hours (eg, 3 hours or 2 hours), preferably within 1 hour, more preferably within 30 minutes, More preferably, it may be 10 minutes to 20 minutes.

  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 developed. A silver conductive layer is formed having a low resistance value (e.g. 15 [mu] [Omega] cm or less, in the range of 5-15 [mu] [Omega] cm). The resistance value of bulk silver is 1.6 μΩcm.

  Since baking at low temperature is possible, polyester-based films 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. Also, general-purpose plastic substrates with low heat resistance such as polyolefin-based films such as polypropylene can be suitably used. In addition, baking in a short time reduces the load on these low heat resistant general-purpose plastic substrates and improves production efficiency.

  Silver conductive materials obtained by the present invention can be used in various electronic devices such as electromagnetic wave control materials, circuit boards, antennas, heat sinks, liquid crystal displays, organic EL displays, field emission displays (FEDs), IC cards, IC tags, solar cells The present invention can be applied to batteries, LED elements, organic transistors, capacitors (capacitors), electronic paper, flexible batteries, flexible sensors, membrane switches, touch panels, EMI shields, and the like. In particular, it is effective for electronic materials that require surface smoothness, for example, as a gate electrode of a thin film transistor (TFT) in a liquid crystal display.

  The thickness of the silver conductive layer may be appropriately determined according to the intended application. There is no particular limitation, and for example, it may be selected from the range of 5 nm to 10 μm, preferably 100 nm to 5 μm, more preferably 300 nm to 2 μm.

  The above description has mainly focused on the ink containing silver nanoparticles, but the present invention is also applicable to the ink containing metal nanoparticles containing metals other than silver.

  EXAMPLES The present invention will be more specifically described below with reference to examples, but the present invention is not limited by these examples.

[Specific resistance value of silver fired film]
The obtained silver fired film was measured using a four-terminal method (Loresta GP MCP-T610). The measurement range limit of this device is 10 ⁷ Ωcm.

The following reagents were used in each example and comparative example.
n-Butylamine (MW: 73.14): Reagent manufactured by Tokyo Chemical Industry Co., Ltd. Reagent 2-ethylhexylamine (MW: 129.25): reagent manufactured by Wako Pure Chemical Industries, Ltd. reagent n-octylamine (MW: 129.25): Tokyo Chemical Co., Ltd. Reagent methanol: Wako Pure Chemical Industries reagent special grade 1-butanol: Wako Pure Chemical Industries reagent special grade silver oxalate (MW: 303.78): silver nitrate (Wako Pure Chemical Industries Ltd.) and oxalic acid dihydrate (Wako pure) Synthesized from Yakusha Co., Ltd.)

Example 1
(Preparation of silver nanoparticles)
A 500 mL flask was charged with 40.0 g (0.1317 mol) of silver oxalate, to which 60 g of n-butanol was added to prepare a silver oxalate n-butanol slurry. Amine mixed solution of 115.58 g (1.5802 mol) of n-butylamine, 51.06 g (0.3950 mol) of 2-ethylhexylamine, and 17.02 g (0.1317 mol) of n-octylamine in this slurry at 30 ° C. Was dropped. After dropping, the mixture was stirred at 30 ° C. for 1 hour to allow complex formation reaction of silver oxalate and amine to proceed. After formation of the silver oxalate-amine complex, the silver oxalate-amine complex is pyrolyzed by heating at 110 ° C. to obtain a suspension in which dark blue silver nanoparticles are suspended in the amine mixture. The

  The resulting suspension was cooled, to which 120 g of methanol was added and stirred, and then the silver nanoparticles were sedimented by centrifugation and the supernatant was removed. Next, 120 g of 1-butanol was added to the silver nanoparticles and stirred, and then the silver nanoparticles were sedimented by centrifugation and the supernatant was removed. Thus, wet silver nanoparticles containing butanol were obtained. According to the result of thermobalance using TG / DTA6300 manufactured by SII, silver nanoparticles accounted for 90 wt% in wet silver nanoparticles.

(Preparation of silver nano ink)
Next, 10 g of wet silver nanoparticles containing butanol were weighed out. Separately, ethyl cellulose [ETCEL (registered trademark) std. 7 (manufactured by Nisshin Kasei Co., Ltd.)], 0.58 g of Terpineol C (manufactured by Nippon Terpene Co., Ltd.) and 1.78 g of ethylene glycol monobutyl ether acetate (manufactured by Daicel Co., Ltd.) are mixed to completely complete the ethyl cellulose. It was dissolved. 3.84 g of the obtained solution was weighed and kneaded with 10 g of the silver nanoparticles. Kneading is carried out for 1 minute with a rotation-revolution-type kneader (Mazuru Star KK 2508, manufactured by Kurashiki Spinning Co., Ltd.), then manually for 1 minute with a spatula, and further with 1 minute of stirring in a kneader and 1 with a spatula. It performed by repeating stirring for a minute. Thus, a black brown silver nanoink was prepared.

  The obtained silver nanoink was subjected to TG-DTA (differential thermal thermal simultaneous analysis) using TG / DTA6300 manufactured by SII, and the silver concentration in the silver nanoink was determined. The silver concentration was 65 wt%. In addition, when the viscosity of the silver nanoink was measured using a rheometer (manufactured by Anton Paar, rheometer MCR 301), 22 Pa · s (5 / s) and 12 Pa · s (10 / s) at each shear rate (/ s) And 5 Pa · s (50 / s).

  The obtained silver nanoink was observed using a scanning electron microscope (JSM-6700F manufactured by JEOL Ltd.) according to a standard method, and the average particle diameter of silver particles was determined. The average particle diameter (primary particle diameter) is 50 nm. It was a degree.

  The average particle size was determined as follows. SEM observation was performed about silver nanoink, the particle diameter of ten silver particles arbitrarily selected in the SEM photograph was calculated | required, and those average value was made into the average particle diameter.

(Printability of silver nano ink)
The silver nanoink was printed on a PEN film by a gravure offset printing apparatus (Mini Lab Fine II, manufactured by Nippon Denshi Seiki Co., Ltd.) having a silicone blanket, and the printability was evaluated. According to CCD observation, L / S = 30 μm / It was confirmed that a thin line of 30 μm was transferable. No ink residue was visually observed on the blanket.

(Firing of silver nano ink)
The silver nanoink was applied on a soda glass plate to form a coating. After forming the coating film, the coating film was immediately fired in a blast drying furnace under the conditions of 150 ° C. and 30 minutes to form a silver fired film having a thickness of 10 μm. When the specific resistance value of the obtained silver fired film was measured by the four-terminal method, it showed a good conductivity of 14.0 μΩcm. Thus, the silver nanoink exhibited excellent conductivity by firing at a low temperature for a short time.

Example 2
Silver nanoparticles were prepared as in Example 1.

(Preparation of silver nano ink)
Next, 10 g of wet silver nanoparticles containing butanol were weighed out. Separately, ethyl cellulose [ETCEL (registered trademark) st. 45 (manufactured by Nisshin Kasei Co., Ltd.)], 0.32 g of Terpineol C (manufactured by Nippon Terpene Co., Ltd.), and 2.32 g of ethylene glycol monobutyl ether acetate (manufactured by Daicel Co., Ltd.) It was dissolved. 3.84 g of the obtained solution was weighed and kneaded with 10 g of the silver nanoparticles. Kneading is carried out for 1 minute with a rotation-revolution-type kneader (Mazuru Star KK 2508, manufactured by Kurashiki Spinning Co., Ltd.), then manually for 1 minute with a spatula, and further with 1 minute of stirring in a kneader and 1 with a spatula. It performed by repeating stirring for a minute. Thus, a black brown silver nanoink was prepared.

The silver concentration in the silver nanoink was 65 wt%.
The viscosity of the silver nanoink was 22 Pa · s (5 / s), 12 Pa · s (10 / s), and 5 Pa · s (50 / s).
The average particle size (primary particle size) of the silver particles was about 50 nm.

(Printability of silver nano ink)
The silver nanoink was printed on a PEN film by a gravure offset printing apparatus (Mini Lab Fine II, manufactured by Nippon Denshi Seiki Co., Ltd.) having a silicone blanket, and the printability was evaluated. According to CCD observation, L / S = 30 μm / It was confirmed that a thin line of 30 μm was transferable. No ink residue was visually observed on the blanket.

(Firing of silver nano ink)
The silver nanoink was applied on a soda glass plate to form a coating. After the formation of the coating film, the coating film was immediately fired in a blast drying furnace under conditions of 120 ° C. for 30 minutes to form a silver fired film having a thickness of 10 μm. When the specific resistance value of the obtained silver fired film was measured by the four-terminal method, it showed a good conductivity of 8.0 μΩcm.

[Example 3]
Silver nanoparticles were prepared as in Example 1.

(Preparation of silver nano ink)
In the same manner as Example 1, except that 1.32 g of 1-methoxy-2-propyl acetate (manufactured by Daicel Co., Ltd.) was used instead of 2.32 g of ethylene glycol monobutyl ether acetate (manufactured by Daicel Co., Ltd.), A black brown silver nanoink was prepared.

The silver concentration in the silver nanoink was 65 wt%.
The viscosity of the silver nanoink was 22 Pa · s (5 / s), 12 Pa · s (10 / s), and 5 Pa · s (50 / s).
The average particle size (primary particle size) of the silver particles was about 50 nm.

(Printability of silver nano ink)
The silver nanoink was printed on a PEN film by a gravure offset printing apparatus (Mini Lab Fine II, manufactured by Nippon Denshi Seiki Co., Ltd.) having a silicone blanket, and the printability was evaluated. According to CCD observation, L / S = 30 μm / It was confirmed that a thin line of 30 μm was transferable. No ink residue was visually observed on the blanket.

(Firing of silver nano ink)
The silver nanoink was applied on a soda glass plate to form a coating. After forming the coating film, the coating film was immediately fired in a blast drying furnace under the conditions of 150 ° C. and 30 minutes to form a silver fired film having a thickness of 10 μm. When the specific resistance value of the obtained silver fired film was measured by a four-terminal method, it showed a good conductivity of 11.0 μΩcm.

[Comparative example 1: no glycol ester solvent]
Silver nanoparticles were prepared as in Example 1.

(Preparation of silver nano ink)
Next, 10 g of wet silver nanoparticles containing butanol were weighed out. Separately, ethyl cellulose [ETCEL (registered trademark) st. 7 (manufactured by Nisshin Kasei Co., Ltd.)] and 0.56 g of Terpineol C (manufactured by Nippon Terpene Co., Ltd.) were mixed to completely dissolve ethyl cellulose. 3.84 g of the obtained solution was weighed and kneaded with 10 g of the silver nanoparticles. Kneading is carried out for 1 minute with a rotation-revolution-type kneader (Mazuru Star KK 2508, manufactured by Kurashiki Spinning Co., Ltd.), then manually for 1 minute with a spatula, and further with 1 minute of stirring in a kneader and 1 with a spatula. It performed by repeating stirring for a minute. Thus, a black brown silver nanoink was prepared.

The silver concentration in the silver nanoink was 65 wt%.
The average particle size (primary particle size) of the silver particles was about 50 nm.

(Printability of silver nano ink)
The silver nanoink was printed on a PEN film by a gravure offset printing apparatus (Mini Lab Fine II, manufactured by Nippon Denshi Seiki Co., Ltd.) having a silicone blanket, and the printability was evaluated. The ink residue was visually observed on the blanket And transfer in intaglio printing was difficult.

Example 4
Silver nanoparticles were prepared as in Example 1.

(Preparation of silver nano ink)
Next, 10 g of wet silver nanoparticles containing butanol were weighed out. Separately, ethyl cellulose [ETCEL (registered trademark) st. 7 (manufactured by Nisshin Kasei Co., Ltd.)] was mixed 0.504 g of terpineol C (manufactured by Nippon Terpene Co., Ltd.) and 0.89 g of 1-methoxy-2-propyl acetate to completely dissolve ethyl cellulose. . 2.86 g of the obtained solution was weighed and kneaded with 10 g of the silver nanoparticles. Kneading is carried out for 1 minute with a rotation-revolution-type kneader (Mazuru Star KK 2508, manufactured by Kurashiki Spinning Co., Ltd.), then manually for 1 minute with a spatula, and further with 1 minute of stirring in a kneader and 1 with a spatula. It performed by repeating stirring for a minute. Thus, a black brown silver nanoink was prepared.

The silver concentration in the silver nanoink was 70 wt%.
The average particle size (primary particle size) of the silver particles was about 50 nm.

(Printability of silver nano ink)
The silver nanoink was printed on a PEN film using a gravure offset printing apparatus (Mini Lab Fine II, manufactured by Nippon Denshi Seiki Co., Ltd.) having a silicone blanket, and the printability was evaluated. Although observed, it was confirmed by CCD observation that a thin line of L / S = 30 μm / 30 μm was transferable.

[Example 5]
Silver nanoparticles were prepared as in Example 1.

(Preparation of silver nano ink)
Ethyl cellulose [ETCEL (registered trademark) st. 7 (manufactured by Nisshin Kasei Co., Ltd.)] in the same manner as in Example 1 except that 0.504 g of an acrylic resin (Orichox KC 1700, manufactured by Kyoeisha Chemical Co., Ltd.) was used instead of 0.504 g. A silver nanoink was prepared.

The silver concentration in the silver nanoink was 65 wt%.
The average particle size (primary particle size) of the silver particles was about 50 nm.

(Printability of silver nano ink)
The silver nanoink was printed on a PEN film by a gravure offset printing apparatus (Mini Lab Fine II, manufactured by Nippon Denshi Seiki Co., Ltd.) having a silicone blanket, and the printability was evaluated. A thin line of L / S = 30 μm / 30 μm In transfer, it was confirmed by CCD observation that a part of a thin line was generated by a whisker, but no ink residue was visually observed on the blanket.

Claims (12)

Silver nanoparticles whose surface is coated with a protective agent containing an aliphatic hydrocarbon amine,
A silver nanoparticle-containing ink for intaglio offset printing, comprising a dispersion solvent containing a terpene solvent and a glycol ester solvent.   The silver nanoparticle-containing ink according to claim 1, wherein the dispersion solvent is contained in a range of 30% by weight or more and 60% by weight or less based on the ink.   The dispersion solvent contains the terpene solvent in a range of 20% by weight to 80% by weight, and the glycol ester solvent in a range of 20% by weight to 80% by weight based on the dispersion solvent. Item 3. The silver nanoparticle-containing ink according to Item 1 or 2.   The silver nanoparticle-containing ink according to any one of claims 1 to 3, further comprising a cellulose-based resin as an additive. The aliphatic hydrocarbon amine includes an aliphatic hydrocarbon monoamine (A) which comprises an aliphatic hydrocarbon group and one amino group, and the total number of carbon atoms of the aliphatic hydrocarbon group is 6 or more,
Furthermore, an aliphatic hydrocarbon monoamine (B) comprising an aliphatic hydrocarbon group and one amino group, and the total number of carbon atoms of the aliphatic hydrocarbon group is 5 or less, and an aliphatic hydrocarbon group and two amino groups Silver nanoparticles according to any one of claims 1 to 4, comprising at least one of aliphatic hydrocarbon diamines (C) consisting of the following: and the total number of carbon atoms of the aliphatic hydrocarbon group is 8 or less. Containing ink.   The aliphatic hydrocarbon monoamine (A) is a linear alkyl monoamine having a linear alkyl group having 6 to 12 carbon atoms, and a branched alkyl having a branched alkyl group having 6 to 16 carbon atoms. The silver nanoparticle-containing ink according to claim 5, which is at least one selected from the group consisting of monoamines.   The silver nanoparticle-containing ink according to claim 5 or 6, wherein the aliphatic hydrocarbon monoamine (B) is an alkyl monoamine having 2 to 5 carbon atoms.   The aliphatic hydrocarbon diamine (C) is an alkylene diamine in which one of two amino groups is a primary amino group and the other is a tertiary amino group. The silver nanoparticle-containing ink according to any one of the above.   The silver nanoparticle-containing ink according to any one of claims 1 to 8, wherein the aliphatic hydrocarbon amine is used in a total amount of 1 to 50 moles with respect to 1 mole of silver atoms of the silver nanoparticles. . Mixing an aliphatic hydrocarbon amine and a silver compound to form a complex compound containing the silver compound and the amine,
The complex compound is heated and pyrolyzed to form silver nanoparticles,
The silver nanoparticles are dispersed in a dispersion solvent containing a terpene solvent and a glycol ester solvent.
And a method for producing a silver nanoparticle-containing ink for intaglio offset printing.   The method for producing a silver nanoparticle-containing ink according to claim 10, wherein the silver compound is silver oxalate.   A silver nanoparticle-containing ink according to any one of claims 1 to 9, or a silver nanoparticle-containing ink produced by the method according to claim 10 or 11, formed by intaglio offset printing, and baking Electronic device having a silver conductive layer.