TWI684631B - Silver particle paint composition and electronic device - Google Patents

Abstract

The object of the present invention is to provide a silver paint composition which exhibits excellent electrical conductivity by firing at a low temperature for a short time, and has excellent adhesion between a silver coating film (silver fired film) and a substrate, and depicts thin lines Sex is also excellent.

The solution of the present invention is to provide a silver particle coating composition comprising silver nanoparticles (N), vinyl chloride-vinyl acetate copolymer resin formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine, and Disperse solvent. The coating composition preferably further contains silver fine particles (M). Suitable for silver particle coating composition for gravure lithography.

Description

Silver particle paint composition and electronic device

The present invention relates to a paint composition containing silver particles. The silver particle coating composition of the present invention is suitable for gravure lithography applications such as gravure lithography. In addition, the present invention is also applicable to a coating composition containing metal particles containing metals other than silver.

Silver nanoparticles can be sintered even at low temperatures. Taking advantage of this property, in the manufacture of various electronic components, in order to form electrodes or conductive circuit patterns on substrates, silver paint compositions containing silver nanoparticles have been used. Silver nanoparticles are usually dispersed in organic solvents. The silver nanoparticle system has an average primary particle size of about several nanometers to several tens of nanometers, and generally, its surface is coated with an organic stabilizer (protective agent). When the substrate is a plastic film or sheet, the silver nanoparticles must be sintered at a temperature lower than the heat-resistant temperature of the plastic substrate (for example, below 200°C).

Especially recently, as a flexible printed wiring board, not only the heat-resistant polyimide which has been used, but also the heat resistance lower than polyimide but easy and cheap to process PET (polyethylene terephthalate) Various plastic substrates such as diesters) and polypropylene have also attempted to form fine metal wiring (for example, silver wiring). When using a plastic substrate with low heat resistance, it is necessary to sinter metal nanoparticles (for example, silver nanoparticles) at a lower temperature.

For example, Japanese Unexamined Patent Publication No. 2008-214695 has disclosed that it involves reacting silver oxalate with oleylamine to form a complex compound containing at least silver and oleylamine and oxalic acid ions, and the resulting complex compound is thermally decomposed to form Silver ultrafine particles manufacturing method of silver ultrafine particles (request 1). It is also revealed that in the above method, in addition to the silver oxalate and the oleylamine, a saturated aliphatic amine having a total carbon number of 1 to 18 is added for reaction (requests 2 and 3), which can easily form a complex and can be shortened The time required for the production of silver ultrafine particles, and the silver ultrafine particles protected by these amines can be produced in higher yields (paragraph [0011]).

Japanese Patent Laid-Open No. 2010-265543 has disclosed a method for manufacturing coated silver ultrafine particles, which includes: a silver compound that is decomposed by heating to produce metallic silver, and a short-chain alkyl amine having a boiling point of 100°C to 250°C and a boiling point The first step of preparing a complex compound containing a silver compound with the aforementioned alkylamine and the aforementioned alkyldiamine by mixing short-chain alkyldiamines between 100°C and 250°C; and the first step of thermally decomposing the aforementioned complex 2 steps (request item 3, paragraphs [0061], [0062]).

Japanese Unexamined Patent Publication No. 2012-162767 discloses a method for manufacturing coated metal fine particles, which includes a first step of mixing an amine solution containing an alkylamine having 6 or more carbon atoms and an alkylamine having 5 or less carbon atoms, and The metal compounds of the metal atoms are mixed to form a complex compound containing the metal compound and the amine; and in the second step, the complex compound is thermally decomposed to generate metal fine particles (claim 1). Furthermore, it is disclosed that the coated silver fine particles can be dispersed in an alcohol solvent such as butanol, a nonpolar solvent such as octane, or an organic solvent such as a mixed solvent thereof (paragraph [0079]).

Japanese Unexamined Patent Publication No. 2013-142172 and International Publication No. WO2013/105530 disclose a method for producing silver nanoparticles, which includes preparing a total of 6 carbons containing an aliphatic hydrocarbon group and one amine group, and the aliphatic hydrocarbon group The above aliphatic hydrocarbon monoamine (A), an aliphatic hydrocarbon monoamine (B) containing an aliphatic hydrocarbon group and one amine group and having a total carbon number of the aliphatic hydrocarbon group of 5 or less, and containing an aliphatic hydrocarbon group and 2 amines An aliphatic amine mixed solution of aliphatic hydrocarbon diamine (C) having a total carbon number of 8 or less, and a silver compound and the amine mixed solution are mixed to form a complex compound containing the silver compound and the amine Then, the aforementioned complex is heated to thermally decompose to form silver nanoparticles (claim 1). Furthermore, it is disclosed that by dispersing the obtained silver nanoparticles in a suitable organic solvent (dispersion medium) in a suspended state, a silver paint composition called so-called "silver ink" can be produced; as an organic solvent, Reveal aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, etc.; such as toluene, xylene, 1,3 , 5-Trimethylbenzene and other aromatic hydrocarbon solvents; such as methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decyl alcohol, etc. Alcoholic solvents (paragraph [0085]).

Japanese Patent Application Publication No. 2013-142173 and International Publication No. WO2013/105531 have disclosed a method for producing silver nanoparticles, which includes preparing an aliphatic hydrocarbon group containing an aliphatic hydrocarbon group and an amine group at a specific ratio. An amine mixture of an aliphatic hydrocarbon monoamine (A) having a total carbon number of 6 or more, and an aliphatic hydrocarbon monoamine (B) containing an aliphatic hydrocarbon group and one amine group and the aliphatic hydrocarbon group having a total carbon number of 5 or less , And the silver compound is mixed with the amine mixture to contain the silver compound and The complex of the amine is formed, and then the complex is heated to thermally decompose to form silver nanoparticles (claim 1). In addition, similar to the aforementioned Japanese Patent Laid-Open No. 2013-142172, it is disclosed that by dispersing the obtained silver nanoparticles in a suitable organic solvent (dispersion medium) in a suspended state, a so-called "silver seal" can be produced. Ink” silver coating composition; it reveals the same organic solvent (paragraph [0076]).

International Publication WO2014/021270 has disclosed a method for manufacturing printing ink containing silver nanoparticles, which includes: an aliphatic hydrocarbon group containing an aliphatic hydrocarbon group and an amine group, and the total carbon of the aliphatic hydrocarbon group being 6 or more Hydrocarbon monoamine (A), and will further include an aliphatic hydrocarbon monoamine (B) containing an aliphatic hydrocarbon group and one amine group and having a total carbon number of the aliphatic hydrocarbon group of 5 or less, and an aliphatic hydrocarbon group and 2 amines At least one of the aliphatic hydrocarbon diamines (C) of the aliphatic hydrocarbon group having a total carbon number of 8 or less is mixed with a silver compound to form a complex compound containing the silver compound and the amine, Then, the complex is heated to thermally decompose to form silver nanoparticles, and the silver nanoparticles are dispersed in a dispersion solvent containing an alicyclic hydrocarbon (claim 1).

International Publication WO2014/024721 has disclosed a method for producing silver nanoparticles, which includes branched fats containing at least a branched aliphatic hydrocarbon group and an amine group, and the branched aliphatic hydrocarbon group having a carbon number of 4 or more The aliphatic amine of the hydrocarbon monoamine (D) is mixed with the silver compound to form a complex compound containing the silver compound and the amine, and then the complex compound is heated to thermally decompose to form silver nanoparticles ( Request item 1).

Japanese Patent Laid-Open No. 2010-55807 has disclosed a conductive paste, which is a conductive paste used in a gravure lithography method using a silicone blanket composed of silicone rubber, which contains Binder resin, conductive powder, and mixed solvent of high swelling solvent and low swelling solvent (request 1) Examples of the conductive powder include silver powder (paragraph [0033]). It reveals that the 50% cumulative diameter D ₅₀ of the particle size distribution of the conductive powder is 0.05 μm or more and 10 μm or less, particularly preferably 0.1 μm or more and 2 μm or less, and also discloses that the scale-like conductive powder and the spherical shape are preferably used together Conductive powder (paragraph [0034]). Japanese Patent Application Publication No. 2010-55807 does not disclose silver nanoparticles formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine. In addition, there is no disclosure about conductive properties.

Japanese Patent Laid-Open No. 2010-90211 has disclosed a conductive ink composition containing conductive particles, and an organic vehicle containing a resin composition and a solvent (request item 1); its use has been disclosed Epoxy resin is used as a resin composition (claim 3); it has been revealed that the conductive particles are Ag particles (claim 10). The conductive ink composition is used to form an electrode by gravure lithography (paragraph [0001]). It is disclosed that the conductive particles contain spherical conductive particles with an average particle diameter of 0.05 μm to 3 μm, and plate-shaped conductive particles with an average sheet diameter of 0.1 μm or more and less than 3 μm (paragraph [0014]). Japanese Patent Application Publication No. 2010-90211 does not disclose silver nanoparticles formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine. Furthermore, the firing conditions in the examples are not described (paragraph [0027], etc.), nor do they disclose the conductive properties due to low-temperature firing.

Japanese Patent Laid-Open No. 2011-37999 has disclosed a conductive printing ink, which contains: conductive powder; a resin that is solid at 25°C; selected from oxycyclobutane-based monomers, epoxy-based monomers and vinyl ethers It is a monomer component of a monomer; a polymerization initiator; and a specific organic solvent, and its viscosity at 25° C. is 3 to 30 Pa‧s (claim 1); it discloses spherical silver powder with a combined average particle size of 1 μm or less, A spherical silver powder with an average particle diameter of 1 μm or more and 3 μm or less is used as a conductive powder (paragraph [0017]). However, when the conductive ink of the same publication is used and low-temperature firing (120° C.), sufficient conductive performance cannot be obtained (paragraph [0054], Table 2). Japanese Patent Laid-Open No. 2011-37999 does not disclose silver nanoparticles formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine.

Japanese Patent Laid-Open No. 2012-38615 has disclosed a conductive silver paste containing silver particles, a resin that is solid at 25°C, and an organic cyclic ether compound (difunctional oxycyclobutane compound) at 25°C The viscosity is 3~30Pa‧s (requests 1, 2, 3); it reveals and uses 1.0~10.0μm silver particles per 100 parts by mass median diameter (D50), 50~200 parts by mass median diameter (D50) Silver particles of 0.2 to 0.9 μm are used as silver particles (request 6, paragraph [0012]). However, when the conductive silver paste of the same publication is used for low-temperature firing (140° C.), sufficient conductive performance cannot be obtained (paragraph [0046], Table 1). Japanese Unexamined Patent Publication No. 2012-38615 does not disclose silver nanoparticles formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine.

Prior technical literature Patent Literature

Patent Literature 1 Japanese Patent Laid-Open No. 2008-214695

Patent Document 2 Japanese Patent Application Publication No. 2010-265543

Patent Document 3 Japanese Patent Application Publication No. 2012-162767

Patent Document 4 Japanese Patent Application Publication No. 2013-142172

Patent Literature 5 WO2013/105530

Patent Document 6 Japanese Patent Application Publication No. 2013-142173

Patent Document 7 WO2013/105531

Patent Document 8 WO2014/021270

Patent Document 9 WO2014/024721 Gazette

Patent Literature 10 Japanese Patent Application Publication No. 2010-55807

Patent Document 11 Japanese Patent Application Publication No. 2010-90211

Patent Document 12 Japanese Patent Application Publication No. 2011-37999

Patent Document 13 Japanese Patent Laid-Open No. 2012-38615

Silver nanoparticles have an average primary particle size of about several nanometers to several tens of nanometers. Compared with particles of micrometer (μm) size, they are easy to aggregate. Therefore, the reduction reaction of the silver compound (the thermal decomposition reactions in Patent Documents 1 to 9 above) is carried out in the presence of an organic stabilizer, and the surface of the obtained silver nanoparticles is subjected to an organic stabilizer (aliphatic amine, fat Protective agents such as carboxylic acids) are coated.

On the other hand, the silver nanoparticles are made into a silver paint composition (silver ink, silver paste) containing the particles in an organic solvent. In order to exhibit electrical conductivity, it is necessary to sinter the silver particles by removing the organic stabilizer that coats the silver nanoparticles after firing after coating on the substrate. If the firing temperature is low, the organic stabilizer becomes difficult to remove. If the degree of sintering of silver particles is insufficient, a low resistance value cannot be obtained. That is, the organic stabilizer present on the surface of the silver nanoparticles helps stabilize the silver nanoparticles, but on the other hand, it hinders the sintering of the silver nanoparticles (especially sintering under low temperature firing).

When an aliphatic amine compound and/or aliphatic carboxylic acid compound having a longer chain (for example, carbon number 8 or more) is used as an organic stabilizer, it is easy to ensure the spacing between the individual silver nanoparticles, so it is easy to make the silver nanoparticles Stabilize. On the other hand, long-chain aliphatic amine compounds and/or aliphatic carboxylic acid compounds are not easily removed when the firing temperature is low.

In this way, the stability of the silver nanoparticles and the low-resistance firing performance at low temperature are a trade-off relationship.

The above Patent Documents 10 to 13 do not disclose silver nanoparticles formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine, nor does it disclose that sufficient electrical conductivity can be obtained by low-temperature firing.

Therefore, an object of the present invention is to provide a silver particle paint composition that exhibits excellent electrical conductivity (low resistance value) by firing at a low temperature for a short time.

Furthermore, the silver coating film (silver fired film) is required to have excellent adhesion to the substrate. The silver coating film is obtained by coating (or printing) the silver particle coating composition on the substrate to be printed and firing it. The above Patent Documents 11 to 13 disclose the use of curable components. In order to harden the hardening component, an initiator is required. Generally speaking, the use of harmful initiators (such as antimony-based initiators) as initiators will bring disadvantages.

Therefore, the object of the present invention is to provide a silver particle coating composition which exhibits excellent conductivity (low resistance value) by firing at a low temperature for a short time, and the silver coating film (silver fired film) and substrate Excellent adhesion.

Incidentally, when the silver particle coating composition is used for gravure lithography, it is necessary to improve the transferability of the silver coating composition from the blanket to the substrate to be printed. In gravure lithography, first, the silver coating composition is filled into the concave portion of the gravure, and the silver coating composition filled into the concave portion is transferred to a blanket (generally made of silicone rubber), and then, the silver coating composition Transfer from the blanket to the substrate to be printed. At this time, the blanket absorbs the solvent of the silver coating composition to a certain extent and swells. Therefore, the adhesion between the silver coating composition and the surface of the blanket decreases, and the transferability from the blanket to the substrate is improved. When the transferability is improved, the drawability of thin lines (straightness of straight lines) is also improved.

Therefore, an object of the present invention is to provide a silver paint composition suitable for gravure lithography, which exhibits excellent conductivity (low resistance value) and silver coating film (silver fired film) by firing at a low temperature for a short time The adhesion to the substrate is excellent, and the drawability of fine lines is also excellent.

The present inventors further completed the present invention using silver nanoparticles prepared by a so-called thermal decomposition method and coating the surface with a protective agent containing an aliphatic hydrocarbon amine, and vinyl chloride-vinyl acetate copolymer resin. The present invention includes the following inventions.

(1) A silver particle paint composition comprising: Silver nanoparticles (N), vinyl chloride-vinyl acetate copolymer resin, and dispersion solvent formed by coating the surface with a protective agent containing an aliphatic hydrocarbon amine.

(2) The silver particle coating composition according to (1) above, wherein in the silver nanoparticles (N), the aliphatic hydrocarbon amine includes an aliphatic hydrocarbon group and an amine group, and the aliphatic hydrocarbon group An aliphatic hydrocarbon monoamine (A) having a total carbon number of 6 or more, and further includes an aliphatic hydrocarbon monoamine (B) containing an aliphatic hydrocarbon group and an amine group and having a total carbon number of the aliphatic hydrocarbon group of 5 or less, and At least one of aliphatic hydrocarbon diamines (C) containing an aliphatic hydrocarbon group and two amine groups and having a total carbon number of the aliphatic hydrocarbon group of 8 or less.

(3) The silver particle coating composition as described in (2) above, wherein the aliphatic hydrocarbon monoamine (A) is selected from linear alkyl groups having a linear alkyl group having 6 to 12 carbon atoms At least one of a group of a monoamine and a branched alkyl monoamine having a branched alkyl group having 6 to 16 carbon atoms.

(4) The silver particle coating composition as described in (2) or (3) above, wherein the aliphatic hydrocarbon monoamine (B) is an alkyl monoamine having 2 to 5 carbon atoms.

(5) The silver particle coating composition as described in any one of (2) to (4) above, wherein one of the two aliphatic amine groups (C) is a primary amine group, and The other one is tertiary amine group alkylene diamine.

‧ The silver particle coating composition according to any one of the above, wherein the aliphatic hydrocarbon amine includes the aliphatic hydrocarbon monoamine (A) and the aliphatic hydrocarbon monoamine (B).

‧ The silver particle paint composition according to any one of the above, wherein the aliphatic hydrocarbon amine includes the aliphatic hydrocarbon monoamine (A) and the aliphatic hydrocarbon diamine (C).

‧ The silver particle coating composition according to any one of the above, wherein the aliphatic hydrocarbon amine includes the aliphatic hydrocarbon monoamine (A), the aliphatic hydrocarbon monoamine (B), and the aliphatic hydrocarbon Diamine (C).

‧ The silver particle paint composition according to any one of the above, wherein the protective agent further contains an aliphatic carboxylic acid in addition to the aliphatic amine.

‧ The silver particle coating composition as described in any one of the above, wherein the protective agent does not contain aliphatic carboxylic acid.

(6) The silver particle paint composition as described in any one of (1) to (5) above, wherein the total number of silver atoms of the silver nanoparticles (N) is 1 mole, and the total amount is 1 to 1. 50 moles of the aforementioned aliphatic hydrocarbon amine.

The silver nanoparticles (N) can form a complex compound containing the silver compound and the amine by mixing the aliphatic hydrocarbon amine and the silver compound as a protective agent, and heating the complex compound to thermally decompose it form.

The aforementioned silver compound is preferably silver oxalate. The silver oxalate molecule contains 2 silver atoms. When the silver compound is silver oxalate, it is preferable to use the aliphatic hydrocarbon amine whose total amount is 2 to 100 moles relative to 1 mole of silver oxalate.

(7) The silver particle paint composition as described in any one of (1) to (6) above, which further contains silver fine particles (M).

(8) The silver particle paint composition according to any one of (1) to (7) above, wherein the dispersion solvent contains a glycol ester-based solvent.

(9) The silver particle paint composition as described in any one of (1) to (8) above, which is used for gravure lithography. The aforementioned gravure lithography includes gravure lithography and the like.

(10) An electronic device comprising: a substrate and a silver conductive layer coated with the silver particle coating composition as described in any one of (1) to (9) above and fired on the substrate to make.

As an electronic device, it includes various wiring boards, modules, and the like.

‧A method for manufacturing an electronic device, comprising: applying the silver particle coating composition as described in any one of the above to a substrate to form a coating layer containing silver particles, and thereafter firing the coating layer, and A silver conductive layer is formed.

The firing system can be carried out at a temperature of 200°C or lower, for example 150°C or lower, preferably 120°C or lower, and 2 hours or shorter, for example 1 hour or lower, preferably 30 minutes or shorter, more preferably 15 minutes or shorter. More specifically, it can be performed under conditions of about 90°C to 120°C and about 10 minutes to 15 minutes, for example, at 120°C and 15 minutes.

‧A metal particle coating composition comprising metal nanoparticles, a vinyl chloride-vinyl acetate copolymer, and a dispersion solvent formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine.

The substrate may be selected from plastic substrates, ceramic substrates, glass substrates, and metal substrates.

In the present invention, the silver particle paint composition includes silver nanoparticles (N) formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine, vinyl chloride-vinyl acetate copolymer resin, and a dispersion solvent.

Silver nanoparticles (N) formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine are prepared by a so-called thermal decomposition method of silver complex. In the present invention, when at least one of aliphatic hydrocarbon monoamines (A) with a total carbon number of 6 or more, aliphatic hydrocarbon monoamines (B) with a total carbon number of 5 or less, and aliphatic hydrocarbon diamines (C) with a total carbon number of 8 or less is used When one is an aliphatic hydrocarbon amine compound functioning as a complexing agent and/or a protective agent, the surface of the formed silver nanoparticles is coated with this aliphatic amine compound.

When the aliphatic hydrocarbon monoamine (B) and the aliphatic hydrocarbon diamine (C) have a short carbon chain length, they are fired at a low temperature of 200°C or lower, such as 150°C or lower, preferably 120°C or lower. Under a short time of 2 hours or less, such as 1 hour or less, preferably 30 minutes or less, it is still easily removed from the surface of the silver particles. In addition, by the presence of the monoamine (B) and/or the diamine (C), the amount of the aliphatic hydrocarbon monoamine (A) adhering to the surface of the silver particles may be small. Therefore, even in the case of firing at the low temperature, the aliphatic amine compounds can be easily removed from the surface of the silver particles in the short time, and the silver particles can be sufficiently sintered.

The vinyl chloride-vinyl acetate copolymer resin functions as a binder resin. With vinyl chloride-vinyl acetate copolymer tree Grease and silver particle coating composition are excellent in the adhesion between the silver coating film (silver fired film) and the substrate. The silver coating film is to apply (or print) and burn the silver particle coating composition on the substrate to be printed Made. In addition, the viscosity of the coating composition can be adjusted by the vinyl chloride-vinyl acetate copolymer resin. With vinyl chloride-vinyl acetate copolymer resin, the silver particle coating composition can be made into a viscosity suitable for gravure lithography applications such as gravure lithography. Therefore, in gravure lithography, the transferability from the blanket to the substrate is improved, and the drawability of thin lines (straightness of straight lines) is improved.

In this way, according to the present invention, a silver particle coating composition (silver-containing ink or silver-containing particle paste) can be provided, which can exhibit excellent conductivity (low resistance value) by firing at a low temperature for a short time . In particular, according to the present invention, it is possible to provide a silver coating composition suitable for gravure lithography, which exhibits excellent conductivity (low resistance value) and silver coating film (silver firing) by firing at a low temperature for a short time (Film formation) excellent adhesion to the substrate, and fine line drawing.

When the silver paint composition further contains silver fine particles (M), in the coating layer of the paint composition on the substrate, the silver nanoparticles (N) enter the gap between the silver fine particles (M). As a result, the contact efficiency between the silver nanoparticles (N) and the silver fine particles (M) becomes better, and the conductivity is improved by firing.

In the silver particle paint composition of the present invention, when the silver nanoparticles (N) (and the silver fine particles (M) when used) are dispersed in a dispersion solvent containing a glycol ester-based solvent, A dispersing solvent, when the coating composition is used for gravure lithography, It can improve the transferability of silver ink from the blanket to the substrate. In gravure lithography, first, the silver coating composition is filled into the concave portion of the gravure, and the silver coating composition filled in the concave portion is transferred to a blanket (usually made of silicone rubber), and then, the silver coating composition Transfer from blanket to substrate. At this time, it is believed that the blanket absorbs the solvent of the silver coating composition to some extent and swells. Therefore, the adhesion between the silver coating composition and the surface of the blanket decreases, and the transferability from the blanket to the substrate is improved.

In addition, the present invention can also be applied to metal particle paint compositions containing metals other than silver.

According to the present invention, it is also preferable to form a conductive film and conductive wiring by gravure lithography on various plastic substrates having low heat resistance such as PET and polypropylene. The silver particle paint composition of the present invention is suitable for the component use of various electronic devices recently.

FIG. 1 CCD observation photograph (x100) of silver ink fine lines produced in Example 1.

FIG. 2 CCD observation photograph (x100) of silver ink fine lines produced in Comparative Example 1.

[Form for carrying out the invention]

The silver particle coating composition of the present invention includes: silver nanoparticles (N) formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine, silver fine particles (M) when used, and vinyl chloride-vinyl acetate copolymerization Resin and dispersing solvent. In addition, the silver particle paint composition system includes both so-called silver ink and silver paste.

[Silver Nanoparticles (N) formed by coating the surface with an aliphatic hydrocarbon amine protective agent]

The silver nanoparticles (N) are prepared by mixing aliphatic hydrocarbon amines and silver compounds to form a complex compound containing the silver compound and the amine, and heating the complex compound to thermally decompose it . In this way, the manufacturing method of the silver nanoparticles (N) mainly includes a complex forming step and a thermal decomposition step of the complex. The obtained silver nanoparticles (N) are subjected to a dispersion step for preparing a coating composition.

In this specification, the term "nano particles" means that the size of the primary particles (average primary particle diameter) determined by the observation results of the scanning electron microscope (SEM) is less than 1000 nm. In addition, the size of the particles means the size (that is, the size of silver itself) other than the protective agent (stabilizing agent) present (covered) on the surface. 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 80 nm, more preferably 1 nm to 70 nm, and still more preferably 1 nm to 60 nm.

In the present invention, as the silver compound, a silver compound that easily decomposes by heating to produce metallic silver is used. As such a silver compound, silver carboxylate such as silver formate, silver acetate, silver oxalate, silver malonate, silver benzoate, silver phthalate, etc.; silver fluoride, silver chloride, silver bromide, silver iodide, etc. can be used Silver halide; silver sulfate, silver nitrate, silver carbonate, etc., but from the viewpoint of so-called metal silver being easily produced by decomposition and not easily producing impurities other than silver, silver oxalate is preferably used. Silver oxalate is advantageous in that it has a high silver content and can directly obtain metallic silver by thermal decomposition without a reducing agent, and it is difficult to retain impurities derived from the reducing agent.

In the case of manufacturing metal nanoparticles containing metals other than silver, the target metal is easily decomposed by heating Instead of the silver compound mentioned above. As such a metal compound, a metal salt corresponding to the above-mentioned silver compound, for example, a metal carboxylate; a metal halide; a metal sulfate, a metal nitrate, a metal carbonate, or the like can be used. Among these, it is preferable to use metal oxalate from the viewpoint of so-called easy generation of metal by decomposition and generation of impurities other than metal. Examples of other metals include Al, Au, Pt, Pd, Cu, Co, Cr, In, and Ni.

Furthermore, in order to obtain a composite with silver, the above-mentioned silver compound and other metal compounds other than the above-mentioned silver may be used in combination. Examples of other metals include Al, Au, Pt, Pd, Cu, Co, Cr, In, and Ni. The silver composite is composed of silver and one or more other metals, and examples include Au-Ag, Ag-Cu, Au-Ag-Cu, and Au-Ag-Pd. Based on the entire metal, silver accounts for at least 20% by weight, usually at least 50% by weight, for example at least 80% by weight.

In the present invention, in the step of forming the complex, the aliphatic hydrocarbon amine and the silver compound may be mixed in the absence of a solvent, but it is preferably mixed in the presence of an alcoholic solvent with a carbon number of 3 or more to contain the silver compound and the foregoing The amine complex is formed.

As the alcohol solvent, an alcohol having 3 to 10 carbon atoms can be used, and preferably an alcohol having 4 to 6 carbon atoms can be used. For example, n-propanol (boiling point bp: 97°C), isopropanol (bp: 82°C), n-butanol (bp: 117°C), isobutanol (bp: 107.89°C), and secondary butanol (bp : 99.5℃), tertiary butanol (bp: 82.45℃), n-pentanol (bp: 136℃), n-hexanol (bp: 156℃), n-octanol (bp: 194℃), 2-octanol ( bp: 174°C) etc. Even so Among them, considering the temperature that can increase the thermal decomposition step of the subsequent complex, the convenience of post-processing after the formation of silver nanoparticles, etc., it is preferably selected from n-butanol, isobutanol, Butanol and hexanol of third grade butanol and third grade butanol. In particular, n-butanol and n-hexanol are preferred.

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

In the present invention, the aliphatic hydrocarbon amine and the silver compound are mixed in the presence of an alcohol solvent having a carbon number of 3 or more, and several types may be adopted.

For example, first, a solid silver compound and an alcohol solvent may be mixed to obtain a silver compound-alcohol slurry [slurry forming step], and then, an aliphatic hydrocarbon amine may be added to the obtained silver compound-alcohol slurry. The so-called slurry system means a mixture of solid silver compounds dispersed in an alcohol solvent. The solid silver compound can be fed into the reaction vessel, and then an alcohol solvent is added thereto to obtain a slurry.

Alternatively, the aliphatic hydrocarbon amine and the alcohol solvent may be fed into the reaction vessel, and then the silver compound-alcohol slurry is added.

In the present invention, as the aliphatic hydrocarbon amine functioning as a complexing agent and/or protective agent, for example, an aliphatic hydrocarbon monoamine (A) containing a hydrocarbon group with a total carbon number of 6 or more, and an aliphatic hydrocarbon group containing An aliphatic hydrocarbon with 1 amine group and the total carbon of the aliphatic hydrocarbon group is 5 or less At least one of a monoamine (B) and an aliphatic hydrocarbon diamine (C) containing an aliphatic hydrocarbon group and two amine groups, and the total carbon number of the aliphatic hydrocarbon group is 8 or less. These components are usually used as an amine mixed liquid, but the mixing of the amine of the silver compound (or its alcohol slurry) does not necessarily need to be carried out using mixed amines. The aforementioned amines may be added sequentially to the aforementioned silver compound (or its alcohol slurry).

Although it is an established term in this specification, the so-called "aliphatic hydrocarbon monoamine" refers to a compound composed of 1 to 3 monovalent aliphatic hydrocarbon groups and one amine group. The so-called "hydrocarbon group" refers to a group consisting only of carbon and hydrogen. However, the aforementioned aliphatic hydrocarbon monoamine (A) and the aforementioned aliphatic hydrocarbon monoamine (B) may also have hetero atoms (atoms other than carbon and hydrogen) containing oxygen atoms or nitrogen atoms in their hydrocarbon groups as necessary. Substituents. The nitrogen atom does not constitute an amine group.

In addition, "aliphatic hydrocarbon diamine" means a divalent aliphatic hydrocarbon group (alkylene group), two amine groups existing through the aliphatic hydrocarbon group, and optionally replacing the hydrogen atom of the amine group Compounds composed of aliphatic hydrocarbon groups (alkyl). However, the aforementioned aliphatic hydrocarbon diamine (C) may optionally have a substituent containing a hetero atom (atom other than carbon and hydrogen) such as an oxygen atom or a nitrogen atom in its hydrocarbon group. The nitrogen atom does not constitute an amine group.

The aliphatic hydrocarbon monoamine (A) having a total carbon number of 6 or more has a high function as a protective agent (stabilizing agent) for the surface of the silver particles generated through its hydrocarbon chain.

The aforementioned aliphatic hydrocarbon monoamine (A) includes a primary amine, a secondary amine, and a tertiary amine. Examples of the primary amines include hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, Saturated aliphatic hydrocarbon monoamines (that is, alkyl monoamines) with straight-chain aliphatic hydrocarbon groups having 6 to 18 carbon atoms, such as tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, and octadecylamine. Examples of saturated aliphatic hydrocarbon monoamines include, in addition to the straight-chain aliphatic monoamines described above, isohexylamine, 2-ethylhexylamine, tertiary octylamine, etc., having a carbon number of 6 to 16, preferably carbon. Branched aliphatic hydrocarbon monoamines with branched aliphatic hydrocarbon groups of 6 to 8. Moreover, cyclohexylamine can also be mentioned. In addition, unsaturated aliphatic hydrocarbon monoamines (that is, alkenyl monoamines) such as oleylamine can be cited.

As the secondary amines, linear ones include N,N-dipropylamine, N,N-dibutylamine, N,N-dipentylamine, N,N-dihexylamine, N,N- Diheptylamine, N,N-dioctylamine, N,N-dinonylamine, N,N-didecylamine, N,N-di-undecylamine, N,N-di-dodecylamine, N- Dialkyl monoamines such as methyl-N-propylamine, N-ethyl-N-propylamine, N-propyl-N-butylamine, etc. Examples of the tertiary amine include tributylamine and trihexylamine.

In addition, examples of the branched form include secondary amines such as N,N-diisohexylamine and N,N-bis(2-ethylhexyl)amine. Further, tertiary amines such as triisohexylamine and tri(2-ethylhexyl)amine can be cited. In the case of N,N-bis(2-ethylhexyl)amine, the carbon number of 2-ethylhexyl group is 8, and the total number of carbons contained in the aforementioned amine compound is 16. In the case of tri(2-ethylhexyl)amine, the total number of carbons contained in the aforementioned amine compound is 24.

Among the above monoamines (A), when they are linear, it is preferably a saturated aliphatic hydrocarbon monoamine having 6 or more carbon atoms. By setting the carbon number to 6 or more, the distance between the amine group and other silver particles when the amine group is adsorbed on the surface of the silver particles can be ensured, so that the effect of preventing the aggregation of the silver particles can be enhanced. The upper limit of carbon number is not particularly limited, but considering the ease of acquisition, burning For ease of removal during production, etc., saturated aliphatic monoamines up to carbon number 18 are generally preferred. In particular, it is preferable to use alkyl monoamines having 6 to 12 carbon atoms, such as hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, and dodecylamine. Among the straight-chain aliphatic hydrocarbon monoamines, only one type may be used, or two or more types may be used in combination.

In addition, when branched aliphatic hydrocarbon monoamine compounds are used, compared to the case of using straight-chain aliphatic hydrocarbon monoamine compounds of the same carbon number, due to the steric factor of branched aliphatic hydrocarbon groups, it can be used more on the surface of silver particles. Less adhesion, and a larger area of the surface of the coated silver particles. Therefore, with a smaller amount of adhesion on the surface of the silver particles, moderate stability of the silver nanoparticles can be obtained. During firing, since the amount of the protective agent (organic stabilizer) to be removed is small, even in the case of firing at a low temperature below 200°C, the organic stabilizer can be efficiently removed, and the sintering of silver particles can be sufficiently performed .

Among the 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 preferred. When the carbon number of the main chain is 5 to 6, it is easy to obtain a moderate stability of the silver nanoparticles. In addition, from the viewpoint of branching the stereo group of the aliphatic group, it is effective to branch from the second carbon atom on the N atom side like 2-ethylhexylamine. As for the branched aliphatic monoamine, 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) may be used in combination with the linear aliphatic hydrocarbon monoamine and the branched aliphatic hydrocarbon monoamine in order to obtain the respective advantages.

The aliphatic hydrocarbon monoamine (B) with a total carbon number of 5 or less has a shorter carbon chain length than the aliphatic monoamine (A) with a total carbon number of 6 or more. It is believed that its function as a protective agent (stabilizer) It is low, but when compared with the aliphatic monoamine (A), the polarity is high and the coordination ability to silver of the silver compound is high, so it is considered to have an effect on the formation of a complex. In addition, since the carbon chain length is short, even if it is fired at a low temperature of, for example, 120°C or less or about 100°C or less, it can still be removed from the surface of the silver particles in a short time of 30 minutes or 20 minutes or less. Low-temperature firing of the obtained silver nanoparticles has an effect.

Examples of the aliphatic hydrocarbon monoamine (B) include ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, secondary butylamine, tertiary butylamine, pentylamine, isoamylamine, tertiary pentamine Saturated aliphatic hydrocarbon monoamines with 2 to 5 carbon atoms (ie alkyl monoamines) such as amines. In addition, dialkyl monoamines such as N,N-dimethylamine and N,N-diethylamine can be cited.

Among these, n-butylamine, isobutylamine, secondary butylamine, tertiary butylamine, amylamine, isoamylamine, tertiary amylamine and the like are preferred, and the above-mentioned butylamines are particularly preferred. Among the aliphatic hydrocarbon monoamines (B), only one type may be used, or two or more types may be used in combination.

The aliphatic hydrocarbon diamine (C) with a total carbon number of 8 or less has a high coordination ability for silver of a silver compound, and has an effect for promoting the formation of a complex. Generally speaking, aliphatic hydrocarbon diamines have a higher polarity than aliphatic hydrocarbon monoamines, and the coordination ability to silver of silver compounds becomes higher. In addition, the aforementioned aliphatic hydrocarbon diamine (C) has an effect of promoting thermal decomposition at a lower temperature and in a shorter time in the thermal decomposition step of the complex, and can produce silver nanoparticles more efficiently. Furthermore, the silver particles containing the aforementioned aliphatic diamine (C) Since the protective film has a high polarity, the dispersion stability of silver particles in a dispersion medium containing a solvent with a high polarity will be improved. In addition, since the aliphatic diamine (C) has a short carbon chain length, even if it is fired at a low temperature of, for example, 120°C or less or about 100°C or less, it can still be made from silver in a short time of 30 minutes or 20 minutes or less. The particle surface is removed, so it has an effect on the low-temperature and short-time firing of the obtained silver nanoparticles.

The aforementioned aliphatic hydrocarbon diamine (C) is not particularly limited, but ethylenediamine, N,N-dimethylethylenediamine, N,N′-dimethylethylenediamine, N, N-diethylethylenediamine, N,N'-diethylethylenediamine, 1,3-propanediamine, 2,2-dimethyl-1,3-propanediamine, N,N-di Methyl-1,3-propanediamine, N,N'-dimethyl-1,3-propanediamine, N,N-diethyl-1,3-propanediamine, N,N'-di Ethyl-1,3-propanediamine, 1,4-butanediamine, N,N-dimethyl-1,4-butanediamine, N,N'-dimethyl-1,4-butanediamine Amine, N,N-diethyl-1,4-butanediamine, N,N'-diethyl-1,4-butanediamine, 1,5-pentanediamine, 1,5-diamine- 2-methylpentane, 1,6-hexanediamine, N,N-dimethyl-1,6-hexanediamine, N,N'-dimethyl-1,6-hexanediamine, 1, 7-heptanediamine, 1,8-octanediamine, etc. These are all alkylene diamines in which at least one of the two amine groups is a primary amine group or a secondary amine group with a total carbon number of 8 or less, which has a high silver coordination ability for silver compounds and is suitable for the formation of complexes Promotion has an effect.

Among these, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-di Ethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-diethyl-1,4-butanediamine, N,N-dimethyl One of the two amine groups such as -1,6-hexanediamine is a primary amine group (-NH ₂ ), and the other is a tertiary amine group (-NR ¹ R ² ). The total carbon number is 8 or less. Base diamine. The preferred alkylene diamine is represented by the following structural formula: R ¹ R ² NR-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; however, the sum of the carbon numbers of R, R ¹ and R ² is 8 or less. The alkylene group usually does not contain heteroatoms (atoms other than carbon and hydrogen) such as oxygen atoms or nitrogen atoms, but may optionally have a substituent containing the aforementioned heteroatoms. In addition, the alkyl group usually does not contain a hetero atom such as an oxygen atom or a nitrogen atom, but may optionally have a substituent containing the aforementioned hetero atom.

If one of the two amine groups is a primary amine group, the silver coordination ability of the silver compound becomes higher, which is conducive to the formation of complexes; the other one is a tertiary amine group, because the tertiary amine group Lack of coordination ability for silver atoms, so it can prevent the formed complex from becoming a complex network structure. When the complex compound becomes a complex network structure, there is a case where the thermal decomposition step of the complex compound requires a high temperature. In addition, among these, from the viewpoint of being able to be removed from the surface of silver particles in a short time even if fired at a low temperature, a diamine having a total number of carbons of 6 or less is preferred, and a diamine having a total number of carbons of 5 or less is more preferred. 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 a total carbon number of 6 or more, the aliphatic hydrocarbon monoamine (B) having a total carbon number of 5 or less, and the aliphatic hydrocarbon diamine (C) having a carbon total number of 8 or less The use ratio of either or both is not particularly limited, but based on all of the aforementioned amines [(A)+(B)+(C)], it can be set to, for example, the aforementioned 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%.

By setting the content of the aforementioned aliphatic monoamine (A) to 5 mol% to 65 mol%, the carbon chain of the (A) component can easily obtain the protection and stabilization function of the surface of the generated silver particles . If the content of the aforementioned (A) component is less than 5 mol%, the performance of the protection and stability function is weak. On the other hand, if the content of the aforementioned (A) component exceeds 65 mol%, the protection and stabilization function is sufficient, but it is difficult to remove the (A) component by low-temperature firing. As the component (A), when the branched aliphatic monoamine is used, the branched fat can be set so as to satisfy the aliphatic monoamine (A): 5 mol% to 65 mol% Monoamines: 10 mol% to 50 mol%.

When the aliphatic monoamine (A) and the aliphatic monoamine (B) and the aliphatic diamine (C) are used, the ratio of their use is not particularly limited, but the All amines [(A)+(B)+(C)] can be used as a reference, for example: the aforementioned aliphatic monoamine (A): 5 mol% to 65 mol%

The aforementioned aliphatic monoamine (B): 5 mol% to 70 mol%

The aforementioned aliphatic diamine (C): 5 mol% to 50 mol%.

As the component (A), when the branched aliphatic monoamine is used, it can be set to the branched form so that the aliphatic monoamine (A) is 5 mol% to 65 mol%. Aliphatic monoamine: 10 mol% to 50 mol%.

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

By setting the content of the aforementioned aliphatic monoamine (B) to 5 mol% to 70 mol %, it is easy to obtain a complex formation promoting effect, and it itself can contribute to low-temperature and short-term firing, in addition , It is easy to obtain the effect of facilitating the removal of the aforementioned aliphatic diamine (C) from the surface of silver particles during firing. When the content of the component (B) is less than 5 mol%, the effect of promoting the formation of the complex is weakened, or the component (C) is not easily removed from the surface of the silver particles during firing. On the other hand, when the content of the component (B) exceeds 70 mol%, although the complex formation promoting effect can be obtained, the content of the aliphatic monoamine (A) becomes relatively small, and it is difficult to obtain the silver produced The protection of the particle surface is stabilized. The lower limit of the content of the aforementioned (B) component is preferably 10 mol% or more, and more preferably 15 mol% or more. The upper limit of the content of the aforementioned (B) component is preferably 65 mol% or less, and more preferably 60 mol% or less.

By setting the content of the aforementioned aliphatic diamine (C) to 5 mol% to 50 mol %, the complex compound formation promoting effect and the thermal decomposition promoting effect of the complex compound can be easily obtained. The protective film of the silver particles of the diamine (C) has a high polarity, so the dispersion stability of the silver particles in the dispersion medium containing a solvent with a high polarity will be improved. When the content of the component (C) is less than 5 mol %, the complex compound formation promoting effect and the thermal decomposition promoting effect of the complex compound are weak. On the other hand, when the content of the component (C) exceeds 50 mol%, the complex compound formation promoting effect and the thermal decomposition promoting effect of the complex compound can be obtained, but relatively, the aliphatic monoamine (A) The content is reduced, and it is not easy to obtain the protection and stability of the surface of the generated silver particles. The lower limit of the content of the aforementioned (C) component is preferably 5 mol% or more, and more preferably 10 mol% or more. The upper limit of the content of the aforementioned (C) component is preferably 45 mol% or less, and more preferably 40 mol% or less.

When the aliphatic monoamine (A) and the aliphatic monoamine (B) are used (the aliphatic diamine (C) is not used), the ratio of their use is not particularly limited, but the above considerations are taken into account The function of the component can be set to, for example, the aforementioned aliphatic monoamine (A): 5 mol% to 65 mol% based on the aforementioned all amines [(A)+(B)]

The aforementioned aliphatic monoamine (B): 35 mol% to 95 mol%.

As the component (A), when the branched aliphatic monoamine is used, it can be set to the branched form so that the aliphatic monoamine (A) is 5 mol% to 65 mol%. Aliphatic monoamine: 10 mol% to 50 mol%.

When the aforementioned aliphatic monoamine (A) and the aforementioned aliphatic diamine (C) are used (the aforementioned aliphatic monoamine (B) is not used), their use ratio is not particularly limited, but the above-mentioned components are considered Function, based on all the aforementioned amines [(A)+(C)], can be set to, for example: the aforementioned aliphatic monoamine (A): 5 mol% to 65 mol%

The aforementioned aliphatic diamine (C): 35 mol% to 95 mol%.

As the component (A), when the branched aliphatic monoamine is used, the branched fat can be set so as to satisfy the aliphatic monoamine (A): 5 mol% to 65 mol% Monoamines: 10 mol% to 50 mol%.

The above-mentioned use ratios of the aliphatic monoamine (A), the aliphatic monoamine (B), and/or the aliphatic diamine (C) are examples, and various changes can be made.

In the present invention, when the aliphatic monoamine (B) and/or the aliphatic diamine (C) having a high coordination energy to silver of the silver compound is used, According to their usage ratio, the amount of the aliphatic monoamine (A) with a total carbon number of 6 or more on the surface of silver particles is reduced. Therefore, even in the case of firing at a low temperature for a short time, the aliphatic amine compounds are easily removed from the surface of the silver particles, and the sintering of the silver particles (N) can be sufficiently performed.

In the present invention, the total amount of the aliphatic hydrocarbon amines [for example (A), (B), and/or (C)] is not particularly limited, but it can be 1 mole relative to the silver atom of the silver compound of the raw material. Set to about 1 to 50 moles. When the total amount of the amine component [(A), (B) and/or (C)] is less than 1 mol relative to 1 mol of the aforementioned silver atom, there are residues that are not converted into The possibility of the silver compound of the complex compound in the subsequent thermal decomposition step impairs the uniformity of the silver particles and causes the coarsening of the particles, and the possibility of remaining the silver compound without thermal decomposition. On the other hand, the total amount of the amine component [(((A), (B) and/or (C)]) is considered not to have too many advantages relative to 1 mole of the silver atom In order to produce a dispersion of silver nanoparticles in a substantially solvent-free manner, the total amount of the amine component can be set to, for example, about 2 moles or more. By setting the total amount of the amine component to 2 to 50 moles The formation step and thermal decomposition step of the complex can be performed well. The lower limit of the total amount of the amine component is 1 mole, preferably 2 mole or more, and more preferably the silver atom of the silver compound. More than 6 moles. In addition, the silver oxalate molecule contains 2 silver atoms.

In the present invention, in order to further improve the dispersibility of the silver nanoparticles (N) to the dispersion medium, an aliphatic carboxylic acid (D) may be further used as a stabilizer. The aforementioned aliphatic carboxylic acid (D) can be used together with the aforementioned amines, and It is used by being contained in the aforementioned amine mixture. By using the aforementioned aliphatic carboxylic acid (D), the stability of the silver nanoparticles can be improved, especially the stability in the state of the paint dispersed in the organic solvent.

As for the aforementioned aliphatic carboxylic acid (D), a saturated or unsaturated aliphatic carboxylic acid can be used. For example, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid, dodecanoic acid, tridecanoic acid, myristic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid , Saturated aliphatic monocarboxylic acids with carbon number 4 or higher, octadecanoic acid, nonanoic acid, eicosanoic acid, eicosenoic acid, etc.; carbon number 8 of oleic acid, elaidic acid, linoleic acid, palmitoleic acid, etc. The above unsaturated aliphatic monocarboxylic acid.

Among these, saturated or unsaturated aliphatic monocarboxylic acids having 8 to 18 carbon atoms are preferred. By setting the carbon number to 8 or more, when the carboxylic acid group is adsorbed on the surface of the silver particles, the distance from other silver particles can be ensured, so that the effect of preventing the aggregation of the silver particles can be enhanced. Considering the ease of acquisition, the ease of removal during firing, etc., in general, saturated or unsaturated aliphatic monocarboxylic acid compounds up to carbon number 18 are preferred. Tejia uses octanoic acid and oleic acid. Among the aliphatic carboxylic acids (D), only one type may be used, or two or more types may be used in combination.

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

In the present invention, a mixed liquid containing each of the aliphatic hydrocarbon amine components used is usually prepared, for example, the aliphatic monoamine (A), the aliphatic monoamine (B), and the aliphatic diamine (C) are prepared. ) Either or both of the amine mixture [the preparation process of the amine mixture].

The amine mixed liquid system can be prepared by stirring each amine (A), (B) and/or (C) component and the aforementioned carboxylic acid (D) component in the case of use at a predetermined ratio at room temperature.

To the silver compound (or its alcohol slurry), an aliphatic hydrocarbon amine mixed liquid containing each amine component is added to generate a complex compound containing the silver compound and the amine [the complex compound forming step]. Each amine component may be added to the silver compound (or its alcohol slurry) one by one without using it as a mixed solution.

In the case of producing metal nanoparticles containing a metal other than silver, a metal compound containing the target metal (or its alcohol slurry) is used instead of the above-mentioned silver compound (or its alcohol slurry).

The silver compound (or its alcohol slurry) or metal compound (or its alcohol slurry) is mixed with a given amount of amine mixture. The mixing system can be carried out at room temperature. The so-called "normal temperature" means 5~40℃ depending on the surrounding temperature. It means, for example, 5 to 35°C (JIS Z 8703), 10 to 35°C, and 20 to 30°C. It may also be a general room temperature (for example, in the range of 15 to 30°C). The mixing at this time can be carried out while stirring, or due to heat generation due to the amine coordination reaction of the silver compound (or metal compound), it is appropriately cooled to the above temperature range For example, about 5 to 15° C. while stirring. When mixing the silver compound and the amine mixture in the presence of an alcohol having a carbon number of 3 or more, stirring and cooling can be performed satisfactorily. The excess of alcohol and amines acts as a reaction medium.

In the thermal decomposition method of silver amine complex, in the past, a liquid aliphatic amine component was first fed into a reaction vessel, and a powdered silver compound (silver oxalate) was put into it. The aliphatic amine component of the liquid is a flammable substance, which is dangerous to the powdered silver compound. That is, there is a risk of ignition due to static electricity generated by the input of the powder silver compound. In addition, there is also a risk that the powdery silver compound is input to locally undergo a complex formation reaction and the fever reaction bursts. Such a danger can be avoided when mixing the silver compound and the amine mixture in the presence of the aforementioned alcohol. Therefore, it is also safe to manufacture on an enlarged scale.

Since the generated complex compound generally exhibits a color corresponding to its constituent components, by detecting the end of the color change of the reaction mixture by an appropriate spectroscopic method, etc., the end point of the formation reaction of the complex compound can be detected. In addition, the complex formed by silver oxalate is generally colorless (white when viewed visually), but in this case, the formation of the complex can also be detected based on morphological changes such as changes in the viscosity of the reaction mixture status. For example, the reaction time for complex formation is about 30 minutes to 3 hours. In this way, the silver-amine complex (or metal-amine complex) can be obtained in a medium containing alcohol and amines as the main body.

Next, the resulting complex is heated and thermally decomposed to form silver nanoparticles (N) [thermal decomposition step of the complex]. If a metal compound containing a metal other than silver is used, it can form Target metal nanoparticles. Without the use of reducing agents, silver nanoparticles (metallic nanoparticles) can be formed. However, an appropriate reducing agent can also be used as needed within the range that does not hinder the effects of the present invention.

In this metal amine complex decomposition method, in general, amines can control the form of the formation of fine particles when the metal in the atomic state generated by the decomposition of the metal compound condenses to form, and by the A film is formed on the surface to prevent re-aggregation of fine particles. That is, it is believed that by heating the complex compound of the metal compound and the amine, the metal compound can be thermally decomposed while maintaining the coordination bond of the amine to the metal atom, thereby generating a metal in an atomic state, and then, coordinated by the amine Metal atoms condense to form metal nanoparticles covered with an amine protective film.

At this time, the thermal decomposition is preferably performed by stirring the complex in a reaction medium mainly composed of alcohol (in the case of use) and amines. The thermal decomposition can be performed within the temperature range where the coated silver nanoparticles (or coated metal nanoparticles) are generated, but from the viewpoint of preventing the amine from detaching from the surface of the silver particles (or the surface of the metal particles), it is preferably at the aforementioned temperature The temperature within the range should be as low as possible. In the case of a silver oxalate complex, it can 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 the complex of silver oxalate, the silver ions are reduced while being decomposed by heating at about 100°C, and coated silver nanoparticles can be obtained. In addition, in general, the thermal decomposition of silver oxalate itself occurs at about 200°C. By forming a silver oxalate-amine complex, the reason why the thermal decomposition temperature can be reduced by about 100°C is not clear, but it can be inferred that When the complex of silver oxalate and amine is formed, the coordination polymer structure formed by pure silver oxalate is cut off.

In addition, the thermal decomposition of the complex is preferably performed in an inert gas environment such as argon, but it can also be thermally decomposed in the atmosphere.

By thermal decomposition of the complex, it becomes a blue shiny suspension. From this suspension, excess amine etc. are removed, for example, sedimentation of silver nanoparticles (or metal nanoparticles), decantation and washing operations with a suitable solvent (water, or organic solvent), Coated silver nanoparticles (N) (or coated metal nanoparticles) to achieve stability of the target [post-processing steps of silver nanoparticles]. After the washing operation, if it is dried, a stable powder of coated silver nanoparticles (or coated metal nanoparticles) can be obtained. However, the silver nanoparticles (N) in the wet state may be supplied to the preparation of the printing ink containing the silver nanoparticles.

The decanting and washing operations use water or organic solvents. As the organic solvent, aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, etc. can be used; cyclohexane Alicyclic hydrocarbon solvents such as; aromatic hydrocarbon solvents such as toluene, xylene, 1,3,5-trimethylbenzene, etc.; alcohol solvents such as methanol, ethanol, propanol, butanol, etc.; acetonitrile; And their mixed solvents.

When considering the application of gravure lithography, the diol-based solvent can also be used as the organic solvent for decanting and washing operations. Examples of the aforementioned glycol-based solvents include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monobutyl ether, Diethylene glycol monobutyl ether (butyl carbitol: BC), propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and other glycol monoethers. As for the aforementioned diol-based solvent, only one type may be used, or two or more types may be used in combination.

Since the reducing agent may not be used in the formation step of the silver nanoparticles of the present invention, there is no by-product derived from the reducing agent, and the separation of the coated silver nanoparticles from the reaction system is also simple, and a high-purity coating can be obtained Silver nanoparticles (N). However, an appropriate reducing agent can also be used as necessary within a range that does not hinder the effects of the present invention.

In this way, silver nanoparticles (N) whose surface is covered with the protective agent used are formed. The aforementioned protective agent includes, for example, the aforementioned aliphatic monoamine (A), and further includes either or both of the aforementioned aliphatic monoamine (B) and the aforementioned aliphatic diamine (C), even when used Contains the aforementioned carboxylic acid (D). The content ratio of them in the protective agent is equivalent to the use ratio of them in the amine mixture. The same is true for metallic nanoparticles.

[Silver particles (M)]

In this specification, the term “fine particles” means that the average particle diameter is 1 μm or more and 10 μm or less. The silver fine particles (M) are different from the aforementioned silver nanoparticles (N), and they are those that do not have an aliphatic hydrocarbon amine protective agent on their surface. In the present invention, the silver fine particle system may be spherical particles, but may also be flake particles. The so-called flake particles mean the aspect ratio, that is, the diameter ratio (diameter/thickness) to the thickness of the fine particles is, for example, 2 or more. Compared with spherical particles, flake particles have a larger contact area with each other, and therefore tend to have better conductivity. Moreover, the average particle diameter of the silver fine particles (M) has a 50% cumulative diameter D50 of the particle size distribution of, for example, 1 μm to 5 μm, preferably 1 μm to 3 μm. When the silver paint composition is used for gravure lithography, from the viewpoint of thin line drawing (for example, L/S=30/30 μm), it is preferable that the particles are small. For silver fine particles, for example, Silbest series TC-507A (shape: sheet, D50: 2.78 μm), TC-505C (shape: sheet, D50: 2.18 μm), TC-905C (shape: sheet, D50: 1.21 μm), AgS-050 (shape: spherical, D50: 1.4 μm), C-34 (shape: spherical, D50: 0.6 μm); AG-2-1C (shape: spherical, 0.9 μm, DOWA ELECTRONICS)). The particle size is calculated by the laser diffraction method.

[Blending ratio of silver nanoparticles (N) and silver microparticles (M)]

In the present invention, when silver fine particles (M) are used, the blending ratio of the silver nanoparticles (N) and the silver fine particles (M) is not particularly limited, but the silver nanoparticles (N) ) And the total of silver fine particles (M) can be set as a basis, for example: silver nanoparticles (N): 10 to 90% by weight

Silver fine particles (M): 10 to 90% by weight.

By setting such a blending ratio, the conductivity improvement effect due to the low-temperature firing of silver nanoparticles (N) and the stability of the silver paint composition due to silver fine particles (M) can be easily obtained Improve the effect.

When the amount of silver nanoparticles (N) is less than 10% by weight, there are few silver nanoparticles (N) that enter the gap between silver microparticles (M), and it is difficult to obtain the contact enhancement effect between silver microparticles (M). In addition, the low-temperature firing effect of silver nanoparticles (N) formed by coating a surface with a protective agent containing aliphatic hydrocarbon amines also becomes relatively small. Therefore, it is difficult to obtain the effect of improving conductivity caused by low-temperature firing. On the other hand, when the amount of silver nanoparticles (N) exceeds 90% by weight, the storage stability of the silver paint composition may be reduced. The silver nanoparticles (N) used in the present invention are coated with a protective agent containing an aliphatic hydrocarbon amine. Although excellent in low-temperature firing, they are used in coatings. When the composition is stored, it may be sintered slowly. Sintering will cause the viscosity of the coating composition to increase. From such a viewpoint, it is preferable to use stable silver fine particles (M) of 10% by weight or more even at around normal temperature.

Preferably it can be set to: Silver nanoparticles (N): 30 to 80% by weight

Silver particles (M): 20~70% by weight; More preferably, it can be set to: Silver nanoparticles (N): 50~75% by weight

Silver fine particles (M): 25-50% by weight.

[Binder Resin]

In the present invention, the silver paint composition contains vinyl chloride-vinyl acetate copolymer resin as the binder resin. The silver coating composition contains vinyl chloride-vinyl acetate copolymer resin to improve the adhesion between the silver fired film (conductive pattern) coated on the substrate to be printed (or printed) and the substrate , And improve the flexibility of the silver burning film. In addition, the viscosity of the coating composition can be adjusted by the vinyl chloride-vinyl acetate copolymer resin. With vinyl chloride-vinyl acetate copolymer resin, the silver particle coating composition can be made into a viscosity suitable for gravure lithography applications such as gravure lithography. Therefore, in gravure lithography, the transferability from the blanket to the substrate is improved, and the drawability of thin lines (straightness of straight lines) is improved.

The vinyl chloride-vinyl acetate copolymer resin is not particularly limited, and various types can be used. As a binder resin of silver nanoparticles (N) and silver fine particles (M) when used, in order to obtain a better function, it is preferably used in a vinyl chloride-vinyl acetate copolymer It contains about 3 to 15% by weight of hydroxyl-containing units such as vinyl alcohol and hydroxy (meth)acrylate. By containing hydroxyl groups, the silver particles (N) and (M) can be dispersed better, and the adhesion to the substrate can also be improved.

Examples of the vinyl chloride-vinyl acetate copolymer resin include SOLBIN C [vinyl chloride/vinyl acetate/vinyl alcohol=87/13/0 (wt%), degree of polymerization 420, number average molecular weight=31,000, and viscosity of 150 mPa ‧S (resin 20wt%, solvent MIBK/toluene=1/1, B-type viscometer, 25℃), K value 48]; SOLBIN A[vinyl chloride/vinyl acetate/vinyl alcohol=92/3/5(wt %), degree of polymerization 420, number average molecular weight = 30,000, viscosity 220 mPa‧s (resin 20wt%, solvent MIBK/toluene=1/1, B-type viscometer, 25°C), K value 48]; SOLBIN AL[vinyl chloride /Vinyl acetate/vinyl alcohol=93/2/5(wt%), polymerization degree 300, number average molecular weight=22,000, viscosity 70mPa‧s (resin 20wt%, solvent MIBK/toluene=1/1, type B viscometer , 25℃), K value 41]; SOLBIN TA5R [vinyl chloride/vinyl acetate/vinyl alcohol=88/1/11(wt%), polymerization degree 300, number average molecular weight=28,000, viscosity 130mPa‧s (resin 20wt %, solvent MIBK/toluene=1/1, type B viscometer, 25°C), K value 41]; TA2, TA3, TAO, etc. SOLBIN series (manufactured by Nissin Chemical Industry), etc.

The amount of the vinyl chloride-vinyl acetate copolymer 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 silver paint composition. With the addition amount of vinyl chloride-vinyl acetate copolymer resin within this range, a silver particle coating composition with a viscosity suitable for gravure lithography applications such as gravure lithography can be easily obtained, and silver fired films and The adhesion of the substrate is improved, and the flexibility of the silver-fired film is improved.

As the binder resin, in addition to the above-mentioned vinyl chloride-vinyl acetate copolymer resin, to the extent that the effect of the above-mentioned vinyl chloride-vinyl acetate copolymer resin is not reduced, for example, polyvinyl butyral resin, polyester resin can also be used , Acrylic resin, ethyl cellulose resin.

The polyethylene butyraldehyde resin is not particularly limited, but preferably the weight average molecular weight (Mw) is about 10,000 to 100,000. Examples of commercially available products of polyvinyl butyral resin include S-LEC B series manufactured by Sekisui Chemical Industry Co., Ltd. The polyester-based resin is not particularly limited, but examples thereof include polycaprolactone triol (Paccel 305 [PCL305] manufactured by DAICEL Co., Ltd. as a commercially available product). As a commercially available product of ethyl cellulose, ETHOCEL (ETHOCEL; registered trademark, Nissin Chemicals) series can be cited.

Thermosetting resins such as phenol-based resins, polyimide-based resins, melamine-based resins, melamine-polyester-based resins, etc., and oxycyclobutane-based monomers, epoxy-based monomers, etc. can also be used for curing Monomer, but as an initiator used to harden the hardenable components, care should be taken not to use harmful initiators (such as antimony-based initiators). In the present invention, since the vinyl chloride-vinyl acetate copolymer resin is used, there is no need to use a curable component.

[Dispersion solvent]

The dispersing solvent may be any solvent that can disperse the silver nanoparticles (N) and the silver fine particles (M) in use, and dissolve the vinyl chloride-vinyl acetate copolymer resin. Examples of the organic solvent used to obtain the silver paint composition include pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, etc. Zhizhi Aliphatic hydrocarbon solvents; alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; aromatic hydrocarbon solvents such as toluene, xylene, 1,3,5-trimethylbenzene, etc.; such as methanol, ethanol, Alcohol solvents such as propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, etc.; glycol-based solvents; glycol ester-based solvents; such as terpenes Terpene solvents such as terpineol and dihydroterpineol. Depending on the desired concentration and viscosity of the silver paint composition (silver ink, silver paste), the type and amount of the organic solvent can be appropriately determined. The same is true for metallic nanoparticles.

As the dispersion solvent, when considering the application of gravure lithography, it is preferable to use a glycol-based solvent or a glycol ester-based solvent. As for the glycol-based solvent, the decantation of the above-mentioned silver nanoparticles (N) can be exemplified as the ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, and ethyl alcohol listed as the organic solvent in the washing operation. Glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether (butyl carbitol: BC), propylene glycol monomethyl ether, dipropylene glycol Glycol monoethers such as monomethyl ether. In addition, examples of the glycol monoether include diethylene glycol monohexyl ether (hexyl carbitol: HC), diethylene glycol mono 2-ethylhexyl ether, and the like. As for the aforementioned diol-based solvent, only one type may be used, or two or more types may be used in combination. The aforementioned diol-based solvent may also be derived from the user used in the decantation and washing operations of silver nanoparticles (N).

Examples of the glycol ester-based solvent include glycol monoester-based solvents and glycol diester-based solvents.

Specific examples of the aforementioned glycol ester-based solvent include ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and diethylene glycol monoethyl ether acetate. Ethylene glycol monoethyl ether acetate, ethyl Glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate (butyl carbitol acetate: BCA), propylene glycol monomethyl ether acetate (PMA; 1-methoxy) -2-propyl acetate), dipropylene glycol monomethyl ether acetate), etc. glycol monoether monoester; ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetic acid Ester, dipropylene glycol diacetate, 1,4-butanediol diacetate (1,4-BDDA, boiling point 230℃), 1,6-hexanediol diacetate (1,6-HDDA , Boiling point 260 ℃), 2-ethyl-1,6-hexanediol diacetate and other glycol diesters. As the aforementioned glycol ester-based solvent, only one type may be used, or two or more types may be used in combination.

In gravure lithography, the diol-based solvent and the diol ester-based solvent have the property of permeating the silicone blanket. By soaking the solvent in the blanket, the blanket-ink interface is dried, the adhesion between the ink and the blanket is reduced, and the effect of improving the transfer of ink from the blanket to the substrate is improved.

Among the aforementioned dispersion solvents, high-boiling solvents having a boiling point of 200° C. or higher are used. However, these solvents have low volatility and are not likely to cause changes in the concentration of silver ink, and are also preferred from the viewpoint of the operating environment. In addition, it is preferable to use at least the glycol diester (diol diacetate) in the dispersion solvent. In order to easily dissolve the vinyl chloride-vinyl acetate copolymer resin, it is preferable to use the aforementioned glycol diester (diol diacetate).

Among these dispersing solvents, the permeability of the aforementioned glycol monoether monoester to the silicone rubber blanket is generally the highest. When the amount of solvent immersed in the blanket increases, the blanket will swell excessively, and the transferability of the ink to the substrate tends to be impaired. Therefore, in order to ensure the aforementioned points The appropriate permeability of the dispersing solvent to the blanket is preferably using the aforementioned glycol monoether, the aforementioned glycol diester, etc., and its permeability to the silicone-made blanket is generally lower than that of the aforementioned glycol monoether monoester.

In the present invention, the dispersing solvent is based on the total amount thereof, based on the silver paint composition, and is, for example, 20% by weight or more and 60% by weight or less, preferably 25% by weight or more and 50% by weight or less, more preferably 25 It is contained in the range of more than 40% by weight. From the viewpoint of gravure lithography applications, when the amount of the dispersing solvent is less than 20% by weight, the amount of solvent is small, and the transfer at the time of printing may not be performed satisfactorily. On the other hand, when the amount of the above-mentioned dispersion solvent exceeds 60% by weight, the amount of solvent is large, and there is a possibility that fine line printing cannot be performed well, and there is a possibility that low-temperature firing cannot be performed well.

In the present invention, the silver paint composition may further contain components other than the above according to the purpose of the present invention.

When considering the application of gravure lithography, the viscosity of the silver coating composition (silver ink) is, for example, in the range of 0.1 Pa‧s or more and 30 Pa‧s or less under the ambient temperature conditions (eg 25° C.) during printing. 5Pa‧s or more and 25Pa‧s or less. When the viscosity of the ink is less than 0.1Pa‧s, the fluidity of the ink is too high, which may cause defects in the ink from the gravure to the blanket, and the transfer of the ink from the blanket to the substrate to be printed. On the other hand, when the viscosity of the printing ink exceeds 30 Pa‧s, the fluidity of the printing ink is too low, and the filling property of the concave portion of the gravure plate may be deteriorated. When the fillability of the recessed portion is deteriorated, the precision of the pattern transferred to the substrate is reduced, and defects such as disconnection of thin lines are generated.

By mixing the powder of the coated silver nanoparticles (N) in the dry state or the wet state obtained in the post-processing step of the silver nanoparticles, the powder of the silver fine particles (M) when used, the chlorine The ethylene-vinyl acetate copolymer resin is mixed and stirred with the above-mentioned dispersing solvent to prepare an ink (or paste) containing silver particles in a suspended state. The aforementioned silver particles may vary depending on the purpose of use, but in the ink containing silver particles, the total amount of silver nanoparticles (N) and silver fine particles (M) may be, for example, 10% by weight or more, or 25% by weight The above is preferably contained at a ratio of 30% by weight or more. The upper limit of the content of the silver particles is based on 80% by weight or less. The mixed silver nanoparticles (N) and silver microparticles (M), vinyl chloride-vinyl acetate copolymer resin, and the dispersing solvent can be mixed and dispersed once or several times.

The silver paint composition (silver ink) obtained according to the present invention is excellent in stability. For example, the silver ink described above is stable at 50% by weight of silver concentration and stored in a refrigerator at 5° C. for a period of one month or more at a temperature of 5° C. without increasing viscosity.

The prepared silver paint composition (silver ink) is applied to the substrate by a well-known coating method, for example, by gravure lithography, and then fired.

By gravure lithography, a patterned silver ink coating layer is obtained, and by firing the silver ink coating layer, a patterned silver conductive layer (silver fired film) is obtained.

In gravure lithography, the silver ink is first filled into the concave portion of the intaglio, so that the silver ink filled into the concave portion is transferred to a general silicone rubber blanket, and then the silver is printed from the blanket Ink transfer Print to the substrate. In the silver ink of the present invention, when a glycol-based solvent and/or glycol ester-based solvent is used as a dispersion solvent, the dispersion solvent will infiltrate the blanket and swell the blanket. With the amount of solvent infiltrating the blanket, the concentration of the silver ink held on the surface of the blanket becomes higher, that is, it is dried. Therefore, the adhesion between the silver ink on the surface of the blanket and the blanket is reduced, and the transferability of the silver ink from the blanket to the substrate is improved.

The silver printing ink contains vinyl chloride-vinyl acetate copolymer resin, so the adhesion of the silver fired film coated on the substrate to be printed (or printed) and fired to the substrate is improved, and the silver fired film is improved Flexible.

Firing can be performed at a temperature of 200°C or lower, for example, room temperature (25°C) or higher and 150°C or lower, preferably room temperature (25°C) or higher and 120°C or lower. However, in order to complete the sintering of silver by firing in a short time, it is preferably carried out at a temperature of 60°C or more and 200°C or less, for example, 80°C or more and 150°C or less, preferably 90°C or more and 120°C or less. The firing time can be appropriately determined in consideration of the coating amount of silver ink, firing temperature, etc., and can be set within, for example, several hours (eg, 3 hours, or 2 hours), preferably within 1 hour, and more preferably within 30 minutes , It is more preferably 10 minutes to 30 minutes.

Since the silver nanoparticles are constructed in the above-described manner, even with such a low-temperature and short-time firing step, the sintering of silver particles can be sufficiently performed. As a result, excellent conductivity (low resistance value) can be exhibited. A silver conductive layer having a low resistance value (for example, 15 μΩcm or less, whose range is 5 to 15 μΩcm) can be formed. The resistance value of bulk silver is 1.6 μΩcm.

Since it can be fired at low temperature, as a substrate, in addition to heat-resistant plastic substrates such as glass substrates and polyimide-based films, polyethylene terephthalate (PET) films and polynaphthalene Widely used plastic substrates with low heat resistance, such as polyester films such as ethylene formate (PEN) films and polyolefin films such as polypropylene. In addition, short-time firing can reduce the burden on such widely used plastic substrates with low heat resistance, and can improve production efficiency.

The silver conductive material obtained according to the present invention can be applied to various electronic devices, such as electromagnetic wave control materials, circuit substrates, antennas, heat radiation plates, liquid crystal displays, organic EL displays, field emission displays (FED), IC cards, IC tags, solar cells , LED components, organic transistors, capacitors (condenser; capacitor), electronic paper, flexible batteries, flexible sensors, membrane switches, touch panels, electromagnetic wave interference (EMI) shielding, etc. It is especially effective for electronic materials that require surface smoothness. For example, it can be effectively used as a gate of a thin film transistor (TFT) in a liquid crystal display.

The thickness of the silver conductive layer can be appropriately set according to the intended use. It is not particularly limited, and can be selected from the range of, for example, 5 nm to 10 μm, preferably 100 nm to 5 μm, and more preferably 300 nm to 2 μm.

The description above mainly focuses on printing inks containing silver nanoparticles, but according to the present invention, it is also applicable to printing inks containing metal nanoparticles containing metals other than silver.

[Example]

In the following, examples are given to further illustrate the present invention, but the present invention is not limited to these examples.

[Specific resistance value of silver-fired film]

The obtained silver burned film was measured using the 4-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 made by Tokyo Chemical Industry Co., Ltd.

2-ethylhexylamine (MW: 129.25): reagent made by Wako Pure Chemical Industries, Ltd.

N-octylamine (MW: 129.25): reagent made by Tokyo Chemical Industry Co., Ltd.

Methanol: Wako Pure Chemical Co., Ltd. reagent grade

1-Butanol: Wako Pure Chemical's reagent grade

Silver oxalate (MW: 303.78): synthesized by silver nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) and oxalic acid dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.)

[Example 1] (Modulation of silver nanoparticles)

A 500 mL flask was charged with 40.0 g (0.1317 mol) of silver oxalate, and 60 g of n-butanol was added to prepare a slurry of silver oxalate in n-butanol. In this slurry, an amine mixture of 115.58 g (1.5802 mol) n-butylamine, 51.06 g (0.3950 mol) 2-ethylhexylamine, and 17.02 g (0.1317 mol) n-octylamine was dropped at 30°C. After dropping, the mixture was stirred at 30°C for 1 hour, and the complex formation reaction between silver oxalate and amine proceeded. After the silver oxalate-amine complex is formed, it is heated at 110°C to thermally decompose the silver oxalate-amine complex to obtain a suspension of dark blue silver nanoparticles suspended in the amine mixture.

The resulting suspension was cooled, 120 g of methanol was added thereto and stirred, and then the silver nanoparticles were settled by centrifugal separation, Remove the supernatant. Next, 120 g of butyl carbitol (diethylene glycol monobutyl ether; manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the silver nanoparticles and stirred, and then the silver nanoparticles were settled by centrifugation to remove the supernatant. In this way, silver nanoparticles containing butyl carbitol in a wet state are obtained. As a result of using the thermal scale TG/DTA6300 manufactured by SII, silver nanoparticles in the wet state accounted for 90 wt% of the silver nanoparticles. That is, butyl carbitol is 10 wt%.

Furthermore, the silver nanoparticles in the wet state were observed by a conventional method using a scanning electron microscope (JSM-6700F manufactured by JEOL Ltd.), and the average particle diameter and average particle diameter of the silver nanoparticles (primary particles) were obtained. (Diameter) is about 50 nm.

The average particle size is determined as follows. SEM observation was performed on the silver nanoparticles, and the particle diameters of 10 silver particles arbitrarily selected in the SEM photograph were obtained, and the average value of them was taken as the average particle diameter.

(Modulation of silver ink)

To 0.9 g of vinyl chloride-vinyl acetate copolymer resin (SOLBIN AL, manufactured by Nissin Chemical Industry Co., Ltd.), 2.0 g of 1,4-butanediol diacetate (1,4-BDDA, manufactured by DAICEL) was mixed, It was dissolved while heating to 100°C. Here, 3.1 g of butyl carbitol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and mixed and stirred as Liquid A.

Measure 1.5g of the obtained liquid A. Measure 1.5g of the above wet silver nanoparticles containing 10wt% butyl carbitol and 2.0g of silver fine particles (Silbest TC-505C, manufactured by Deli Chemical Research Institute), and add 1.5 to these silver particles g The above liquid A is a rotation-revolving mixer (made by Kurabo Industries Co., Ltd., MAZERUSTAR KKK2508) Stir for 30 seconds. Thereafter, stir with a spatula for 1 minute. Repeat two more times with a mixer for 30 seconds and with a spatula for 1 minute. In this way, dark brown silver ink was obtained.

Table 1 shows the blending composition of silver ink. In Table 1, the composition of each component is expressed in parts by weight when the entirety is 100 parts by weight. As mentioned above, in terms of "wet silver nanoparticles in silver nanoparticles account for 90wt%",

"1.5g silver nanoparticles in a wet state" = "1.35g silver nanoparticles itself" + "0.15g butyl carbitol".

Therefore, Table 1 shows "27 parts by weight of the silver nanoparticles themselves" and "3 parts by weight of butyl carbitol (silver nanoparticles washing portion)".

In addition, "A 15.5 parts by weight of butyl carbitol (solvent component)" was shown in the liquid A.

The silver concentration in the silver ink is 67wt%.

(Printing suitability of silver ink)

The silver printing ink was printed on a PEN film by a gravure lithography apparatus (manufactured by Nippon Seiki Co., Ltd., MINI Lab FINE II) with a silicone rubber blanket, and the printability was evaluated, and the confirmation line was observed with a CCD Thin lines with a width of 30 μm can be transferred. Moreover, as shown in Fig. 1, the straight line drawing property is very good. No ink residue on the blanket was observed visually.

(Adhesion to substrate)

The aforementioned silver ink was applied to the ITO film and dried at 120°C for 30 minutes to form a coating film with a thickness of 5 μm. For the obtained coating film, cellophane was used in accordance with JIS K5600 An adhesive tape (manufactured by Nichiban Co., Ltd.) was subjected to a cross cut test (25 grids). Shows good adhesion.

Good: Peel off is 0/25

Bad: peeling is 1/25 or more

(Sintering of silver ink: evaluation of conductivity)

The aforementioned silver printing ink is coated on a soda glass plate to form a coating film. After the coating film was formed, the coating film was quickly fired at 120° C. for 30 minutes in a forced-air drying furnace to form a silver fired film with a thickness of 5 μm. The specific resistance value of the obtained silver fired film was measured by the 4-terminal method, and it showed good conductivity of 10.1 μΩcm. In this way, the aforementioned silver printing ink exhibits excellent conductivity by firing at a low temperature for a short time.

[Comparative Example 1]

As in Example 1, silver nanoparticles were prepared.

(Modulation of silver ink)

Use 0.9 g of polyethylene butyraldehyde resin (S-LEC BL-1, manufactured by Sekisui Chemical Industry Co., Ltd.) instead of 0.9 g of the vinyl chloride-vinyl acetate copolymer resin (SOLBIN AL, manufactured by Nissin Chemical Industry Co., Ltd.) of Example 1 In the same manner as in Example 1, dark brown silver ink was prepared.

The silver concentration in the silver ink is 67wt%.

(Printing suitability of silver ink)

The silver printing ink was printed on a PEN film by a gravure lithography apparatus (manufactured by Nippon Seiki Co., Ltd., MINI Lab FINE II) with a silicone rubber blanket, and the printability was evaluated, and the confirmation line was observed with a CCD Thin lines with a width of 30 μm can be transferred. However, as shown in FIG. 2, the straight line drawability is inferior to Example 1. No ink residue on the blanket was observed visually.

(Adhesion to substrate)

In the same manner as in Example 1, using the silver ink described above, a coating film with a thickness of 5 μm was formed on the ITO film. A cross peel test (25 grids) was performed on the obtained coating film. Shows good adhesion.

(Sintering of silver ink)

In the same manner as in Example 1, a silver fired film with a thickness of 5 μm was formed on a soda glass plate using the aforementioned silver ink. The specific resistance value of the obtained silver fired film was measured by the 4-terminal method, and it was a value as high as 100 μΩcm, which was quite inferior to Example 1.

The above results are shown in Table 1.

Claims (10)

A silver particle coating composition comprising: silver nanoparticles (N) formed by coating a surface with a protective agent containing an aliphatic hydrocarbon amine, vinyl chloride-vinyl acetate copolymer resin, and a dispersion solvent; the silver particle coating In the composition, the silver nanoparticles (N) have an average primary particle size of 0.5 nm to 100 nm, and the vinyl chloride-vinyl acetate is included in an amount of 0.1% by weight or more and 10% by weight or less based on the silver particle paint composition. The ester copolymer resin contains a dispersion solvent in an amount of 20% by weight or more and 60% by weight or less based on the silver particle paint composition. The silver particle coating composition according to claim 1, wherein in the silver nanoparticles (N), the aliphatic hydrocarbon amine includes: an aliphatic hydrocarbon group and an amine group, and the total carbon of the aliphatic hydrocarbon group is 6 or more Aliphatic hydrocarbon monoamine (A); and further includes an aliphatic hydrocarbon monoamine (B) containing an aliphatic hydrocarbon group and one amine group and the total carbon number of the aliphatic hydrocarbon group is 5 or less, and containing an aliphatic hydrocarbon group and 2 Each amine group and the total carbon number of the aliphatic hydrocarbon group is at least one of aliphatic hydrocarbon diamines (C) of 8 or less. The silver particle coating composition according to claim 2, wherein the aliphatic hydrocarbon monoamine (A) is selected from a linear alkyl monoamine containing a linear alkyl group having 6 to 12 carbon atoms, and a carbon At least one of the group of branched alkyl monoamines having a branched alkyl number of 6 or more and 16 or less. The silver particle paint composition according to claim 2, wherein the aliphatic hydrocarbon monoamine (B) is an alkyl monoamine having 2 to 5 carbon atoms. The silver particle coating composition according to claim 2, wherein the aforementioned aliphatic hydrocarbon diamine (C) is one of the two amine groups is a primary amine group and the other is a tertiary amine group alkylene diamine . The silver particle paint composition according to claim 1, wherein the aliphatic hydrocarbon amine is used in a total amount of 1 to 50 moles relative to 1 mole of silver atoms of the silver nanoparticles (N). The silver particle paint composition according to claim 1, further comprising silver fine particles (M). The silver particle paint composition according to claim 1, wherein the dispersion solvent contains a glycol ester-based solvent. The silver particle coating composition according to claim 1, which is used for gravure lithography. An electronic device comprising: a substrate and a silver conductive layer, which are coated with the silver particle paint composition according to claim 1 on the aforementioned substrate and fired.

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