JP2010037574A - Metal nanoparticle paste and pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide metal nanoparticle paste which has an excellent balance in fluidity and viscosity or spinnability even without using a binder resin and can clearly form a fine pattern even by intaglio offset printing. <P>SOLUTION: In the metal nanoparticle paste comprising: metal colloidal particles (A) formed from metal nanoparticles (A1) and protective colloid (A2) covering the metal nanoparticles (A1); and a dispersion medium (B) for the metal colloidal particles, the protective colloid (A2) is composed of 1-10C amines (A2-1) which do not have a hydroxy group, 1-3C carboxylic acids (A2-2) and amines (A2-3) which have a hydroxy group, and also, in the protective colloid composing all the metal colloidal particles contained in the paste, the ratio of the amines which have a hydroxy group is regulated to 1 to 35 pts.mass based on the total 100 pts.mass of the 1-10C amines which do not have a hydroxy group and the 1-3C carboxylic acids. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a paste (metal nanoparticle paste or metal colloid) comprising metal colloid particles composed of metal nanoparticles (or metal fine particles, silver nanoparticles, etc.) and a surface protective agent (protective colloid) of the metal nanoparticles. Particle paste). More specifically, it can be printed with high printability in printing such as intaglio printing (for example, intaglio offset printing), and a metal film or sintered pattern can be formed even at a heat treatment temperature of very low temperature (for example, 150 ° C. or less). The present invention relates to a metal nanoparticle paste that can be formed.

  Metal nanoparticles (or metal colloid particles) have a large specific surface area and a high reaction activity. For this reason, it is known that it has a property of being fused (low temperature sintering) at a low temperature as compared with bulk or metal atoms, and it is expected to be applied to various fields by taking advantage of this property. For example, an attempt has been made to form a pattern using a paste containing metal nanoparticles. Conventionally, such a pattern has been formed using a hybrid paste in which metal nanoparticles and metal filler (particles having a particle size of the order of microns) are mixed. However, in such a paste, since the metal filler is mixed, the sintering temperature has to be increased, and the metal filler having a large particle size is used, so that there is a limit to the miniaturization of the pattern.

  Under such circumstances, attempts have been made to form a fine pattern using only metal nanoparticles. For example, JP 2004-273205 A (Patent Document 1) is a conductive nanoparticle paste containing metal nanoparticles, and the average particle diameter of the metal nanoparticles is selected in the range of 1 to 100 nm, The conductive nanoparticle paste is a dispersion obtained by uniformly dispersing the metal nanoparticles in a dispersion solvent, and the metal nanoparticle surface has a coordinate bond with a metal element contained in the metal nanoparticle. As a possible group, a compound containing a nitrogen, oxygen or sulfur atom and capable of coordinative bonding by a lone pair of these atoms, having a specific melting point and boiling point (such as a monoalkylamine) It is coated at a specific ratio, and the dispersion solvent is an organic solvent having a specific melting point and boiling point having high solubility capable of dissolving the compound that coats the surface of the metal nanoparticles. Conductive nanoparticle paste containing 8 to 220 parts by mass of the dispersion solvent with respect to 100 parts by mass of the metal nanoparticles (Claim 1), a highly conductive material comprising a sintered body layer of metal nanoparticles on a substrate. A method of forming a fine wiring pattern having a property of forming a coating layer of the fine wiring pattern to be drawn on a substrate surface using the paste, and metal nano contained in the coating layer Firing the particles to form a sintered body layer between the metal nanoparticles, and forming the sintered body layer between the metal nanoparticles at a temperature not exceeding 300 ° C. When the layer is heated, the compound is dissociated and eluted from the surface of the metal nanoparticles in the dispersion solvent when the heating in the baking treatment is performed, and the surface contact between the metal nanoparticles is achieved, The gold And sintering of the nanoparticles cross, method of forming a fine wiring pattern (claim 7) is disclosed that the evaporation removal of the dispersing solvent is made.

  However, although the paste of this document can form a pattern at a relatively low temperature, there is a limit to reducing the firing temperature because of the use of a high-boiling component. Therefore, the substrate on which the pattern is formed is limited, and it is difficult to realistically form a practical pattern (such as a low resistance value pattern) that can be used as a wiring material or the like on a resin substrate or the like. In addition, even with the paste of this document, fine pattern printing is possible as compared with the conventional metal powder paste, but in order to obtain low-temperature sinterability, metal nanoparticles having a protective colloid with a smaller number of carbon atoms are used. In addition, the dispersibility in the dispersion medium is lowered and the fluidity is also lowered. Furthermore, in order to perform clear printing in intaglio offset printing having a transfer process using a silicone blanket, in addition to appropriate fluidity, appropriate viscosity and stringiness required for transfer are also required. The characteristics are not sufficient.

  In order to improve the printability in intaglio offset printing, for example, JP 2005-111665A (Patent Document 2) proposes an offset printing blanket having a specific surface rubber layer. This document describes blending a binder resin with a metal powder for conductive ink used for offset printing.

However, in this conductive ink composition, the printing property of the intaglio can be easily controlled by adjusting the binder resin, but the low-temperature sinterability decreases due to the presence of the binder resin. Furthermore, the metal concentration in the paste cannot be increased due to the blending of the binder resin.
JP 2004-273205 A (Claims, paragraphs [0017], [0019], [0025], [0026]) JP-A-2005-111665 (Claims, paragraphs [0017], [0019], [0025], [0026])

  Accordingly, an object of the present invention is a metal that has an excellent balance between fluidity and viscosity or spinnability without using a binder resin, and can form a fine pattern clearly even by intaglio printing (for example, intaglio offset printing). An object of the present invention is to provide a nanoparticle paste and a pattern forming method using the paste.

  Another object of the present invention is to use a metal nanoparticle paste capable of efficiently forming a sintered layer (especially a conductive layer) or a sintered pattern even at a low temperature (especially a low temperature of about 150 ° C. or less) and this paste. It is to provide a method for forming a pattern.

  As a result of intensive studies to achieve the above problems, the present inventor has found that the protective colloid (or dispersant) for coating or protecting the metal nanoparticles has a specific number of amines and a specific carbon having no hydroxyl group. Using a paste (concentrated dispersion) containing specific metal colloidal particles composed of a number of carboxylic acids and amines having a hydroxyl group provides a good balance between fluidity and viscosity or spinnability. And found that a fine pattern can be clearly formed, and completed the present invention.

That is, the metal nanoparticle paste of the present invention (metal nanoparticle-containing paste) is composed of metal colloid particles (A1) and protective colloids (A2) covering the metal nanoparticles (A1) (A2). ) And a dispersion medium (B) of the metal colloid particles, wherein the protective colloid (A2) is an amine having 1 to 10 carbon atoms (A2-1) having no hydroxyl group. Protective colloid comprising carboxylic acids having 1 to 3 carbon atoms (A2-2) and amines having hydroxyl groups (A2-3) and constituting all metal colloid particles contained in the paste, having hydroxyl groups The proportion of amines is 1 to 35 with respect to 100 parts by mass in total of the amine having 1 to 10 carbon atoms and the carboxylic acid having 1 to 3 carbon atoms not having a hydroxyl group. It is the amount part. In such a metal nanoparticle paste, the amines (A2-1) are mono C _4-10 alkylamines, and the carboxylic acids (A2-2) are C _1-3 saturated aliphatic monocarboxylic acids, The amines (A2-3) may be C _2-6 alkanolamine. Further, in the protective colloid constituting the all metal colloid particles contained in the paste, the ratio (mass ratio) of the amine having 1 to 10 carbon atoms having no hydroxyl group and the amine having hydroxyl group is the former / The latter may be about 99/1 to 50/50. The metal constituting the metal nanoparticles (A1) may be silver alone, and the average particle diameter of the metal nanoparticles (A1) may be 10 nm or less. The ratio of the protective colloid (A2) is 1 to 60 parts by mass with respect to 100 parts by mass of the metal nanoparticles (A1), and the total amount of the amines (A2-1) and the amines (A2-3). The ratio of the carboxylic acids (A2-2) to the former / the latter (mass ratio) may be about 85/15 to 50/50. The dispersion medium (B) may be a polar solvent having a boiling point of 100 to 300 ° C. The metal nanoparticle paste of the present invention includes a first paste that does not contain the amines (A2-3) as a protective colloid, and a first paste that contains the amines (A2-3) as a protective colloid, The paste may be included in a ratio (mass ratio) of first paste / second paste = 10/90 to 90/10 in terms of solid content.

  In the present invention, a pattern (for example, an electrode or a wiring pattern) is formed (or drawn) on the substrate with the metal nanoparticle paste, and the formed pattern (drawing pattern) is baked to form a sintered pattern. A pattern forming method for forming the film is also included. In such a pattern forming method, a pattern may be formed (drawn) by intaglio offset printing. In the method of the present invention, a sintered pattern can be formed even at a low firing temperature. For example, in the above method, a resin base material may be used as a substrate and firing may be performed at a firing temperature of 150 ° C. or lower.

  In the method of the present invention, since a paste containing metal nanoparticles at a high concentration is used, an ultrafine (ultrafine) pattern can be formed. For example, in the above method (for example, pattern formation by an intaglio offset printing method) A sintered pattern having a minimum line width of 20 μm or less can also be formed.

  In the metal nanoparticle paste of the present invention, the protective colloid covering the metal nanoparticles is not an organic binder (resin binder), but is composed of a specific compound that easily evaporates or decomposes at a low temperature and also acts as a binder. A fine pattern can be clearly formed by intaglio printing (for example, intaglio offset printing) which is excellent in the balance between the properties and the viscosity or the spinnability and requires these characteristics. Furthermore, a sintered layer (especially a conductive layer) or a sintered pattern can be formed efficiently even at low temperatures (especially at a very low temperature of 150 ° C. or less). it can. Furthermore, the metal nanoparticle paste of the present invention does not contain a metal filler like the conventional paste, can form a fine pattern, does not contain a binder resin, and remains in the metal film (sintered film) after heat treatment. Since organic residue can be greatly reduced, the influence on metal film characteristics (for example, specific resistance) can be suppressed, which is extremely useful.

[Metal nanoparticle paste]
The metal nanoparticle paste of the present invention is a paste containing metal colloid particles (A) having a specific compound as a protective colloid and a dispersion medium (B) of the metal colloid particles.

(A) Metal colloid particles The metal colloid particles (A) are metal colloid particles coated with metal nanoparticles (A1) and a protective colloid (A2) covering the metal nanoparticles (A1). The colloid (A2) is composed of a combination of specific compounds.

(A1) Metal nanoparticles As the metal (metal atom) constituting the metal nanoparticles (A1), for example, transition metals (for example, periodic table group 4A metals such as titanium and zirconium; periodic tables such as vanadium and niobium) Periodic table Group 6A metals such as molybdenum and tungsten; Group 7A metals such as manganese; Periodic table Group 8 such as iron, nickel, cobalt, ruthenium, rhodium, palladium, rhenium, iridium and platinum Metal; periodic table group 1B metals such as copper, silver, gold), periodic table group 2B metals (for example, zinc, cadmium, etc.), periodic table group 3B metals (for example, aluminum, gallium, indium, etc.), Periodic table group 4B metals (eg, germanium, tin, lead, etc.), periodic table group 5B metals (eg, antimony, bismuth, etc.), etc. Can be mentioned. Metals are periodic group 8 metal (iron, nickel, rhodium, palladium, platinum, etc.), periodic table group 1B metal (copper, silver, gold, etc.), periodic table group 3B metal (aluminum, etc.) and periodic table. It may be a Group 4B metal (such as tin). In many cases, the metal (metal atom) is a metal having a high coordination property to the protective colloid, for example, a Group 8 metal of the periodic table, a Group 1B metal of the periodic table, or the like.

  The metal nanoparticles (A1) may be the metal simple substance, the metal alloy, metal oxide, metal hydroxide, metal sulfide, metal carbide, metal nitride, metal boride and the like. These metal nanoparticles (A1) can be used alone or in combination of two or more. In many cases, the metal nanoparticles (A1) are usually single metal particles or metal alloy particles. In addition, the metal nanoparticles (A1) may be conductive metal particles, in particular. Among them, the metal constituting the metal nanoparticles (A1) is a metal (noble metal simple substance and noble metal alloy) including at least a noble metal such as silver (especially Group 1B metal of the periodic table), particularly a noble metal simple substance (eg, silver simple substance). Is preferred.

  The metal nanoparticles (A1) are nanometer-sized metal fine particles. For example, the average particle diameter (average primary particle diameter) of the metal nanoparticles (A1) in the metal colloid particles of the present invention is 0.5 to 100 nm (for example, 1 to 80 nm), preferably 1.5 to 70 nm (for example, 1.8 to 50 nm), more preferably about 2 to 40 nm (for example, 2 to 30 nm), particularly 10 nm or less (for example, about 1 to 10 nm, preferably about 1 to 8 nm).

  Further, the metal colloid particles (A) may be particles containing almost no coarse particles. In such metal colloidal particles (A), the maximum primary particle diameter of the metal nanoparticles (A1) may be, for example, 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less. Furthermore, in such metal nanoparticles (A1) (or metal colloid particles), the proportion of particles having a primary particle diameter of 100 nm or more is, for example, 10% by mass or less (for example, based on the mass of the metal (or metal component)) 0 to 8% by mass), preferably 5% by mass or less (for example, 0.01 to 3% by mass), more preferably 1% by mass or less (for example, about 0.02 to 0.5% by mass). May be.

(A2) Protective colloid The protective colloid (A2) is composed of an amine having 1 to 10 carbon atoms (A2-1) having no hydroxyl group, a carboxylic acid having 1 to 3 carbon atoms (A2-2), and a hydroxyl group. And amines (A2-3) having In the present invention, by forming such a protective colloid in combination of a specific amine and a specific carboxylic acid, the metal nanoparticles can be efficiently protected with high stability. The reason why such a high stability can be protected is not clear, but metal nanoparticles are formed by a plurality of types of amines and carboxylic acids that are electrostatically bonded by an acid-base reaction and apparently polymerized. This is considered to be because it can be efficiently protected. When amines or carboxylic acids are used alone, the metal nanoparticles cannot be stably protected, and the metal nanoparticles tend to aggregate.

  Furthermore, when any one of the amines is used alone, the printing property of the intaglio is lowered. The reason for improved printability is not clear, but combining amines (amines that do not have a polar group) with amines that have hydroxyl groups improves the balance between viscosity and fluidity in offset printing. Intaglio printing improves the transfer of paste to a blanket (eg, silicone blanket) and suppresses transfer of paste (dirt) remaining outside the printed pattern area to the blanket (eg, silicone blanket) it can.

  In the present invention, the colloidal metal particles are particularly stable by forming a protective colloid with amines having 1 to 10 carbon atoms, carboxylic acids having 1 to 3 carbon atoms and amines having a hydroxyl group. Since such a protective colloid can be separated from the metal colloid particles even at a very low temperature (for example, 150 ° C. or less), it can be sintered at such a low temperature.

(A2-1) C1-C10 amine which does not have a hydroxyl group An amine (A2-1) is a C1-C10 amine which does not have a hydroxyl group. The amines (A2-1) include monoamines and polyamines.

Examples of monoamines include primary amines [eg, monoalkylamines (propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine (n-octylamine, 2-ethylhexylamine, etc.), nonylamine, C _3-10 alkyl amines such as decylamine, preferably C _4-10 alkyl amine, more preferably such C _6-9 alkyl amines), cycloalkyl amines (e.g., cyclopentylamine, such as cyclohexylamine C _{4- 10} cycloalkylamine), arylamines (for example, C _6-10 arylamines such as aniline, toluidine, and aminonaphthalene), aralkylamines (such as benzylamine), etc.], secondary amines [eg, dialkylamines (Dipropylamine, dii Propylamine, and di-C _3-10 alkyl amine, such as dibutylamine), alkylcycloalkyl amines (such as methyl cyclohexylamine), alkylaryl amines (N- methylaniline, etc.), cyclic secondary amines (e.g., Piperidine, 5-8-membered cyclic secondary amines such as hexamethyleneimine), etc.], tertiary amines [eg, trialkylamines (eg, C _3-10 trialkylamines such as tripropylamine), cyclo Alkyldialkylamines (such as cyclohexyldimethylamine), aryldialkylamines (such as N, N-dimethylaniline), and cyclic tertiary amines (eg, 5- to 8-membered cyclic tertiary amines such as pyridine, picoline, quinoline) 1,8-diazabicyclo [5.4.0] undecene-1) ] And the like.

Examples of polyamines include polyamines corresponding to the monoamines such as chain polyamines [eg, alkane diamines (C _2-10 alkane diamines such as ethylene diamine, propylene diamine, tetramethylene diamine, hexamethylene diamine), etc. Diamines; primary polyamines such as polyalkylene polyamines (or polyalkylene imines such as poly _C2-4 alkylene polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine)], cyclic polyamines [e.g. Cyclic secondary polyamines (for example, piperazine, 1,4,8,11-tetraazacyclotetradecane, triethylenediamine, etc.), cyclic tertiary polyamines (pyrimidine, etc.) and the like.

  These amines may be used alone or in combination of two or more.

Among these amines, for example, monoalkylamines [for example, monoalkylamines having 4 or more carbon atoms (for example, 4 to 10 carbon atoms) such as octylamine (especially mono C _6-9 alkylamines), etc. ] Is preferable.

  The amine having 1 to 10 carbon atoms (A2-1) may be liquid or solid at room temperature (or room temperature, for example, 25 ° C.), and particularly liquid. The boiling point of liquid amines is 45-350 degreeC (for example, 50-320 degreeC), for example, Preferably it is 60-300 degreeC (for example, 80-280 degreeC), More preferably, it is 100-250 degreeC (for example, 120- About 230 ° C.). Further, the amines (A2-1) may be a compound that decomposes or evaporates at a firing temperature described later (for example, about 100 to 350 ° C., preferably about 120 to 300 ° C.).

(A2-2) Carboxylic acids having 1 to 3 carbon atoms The carboxylic acids having 1 to 3 carbon atoms (A2-2) may be any compound having at least one carboxyl group, and carboxyls of carboxylic acids (A2-2). The number of groups may be, for example, about 1-2.

  In the carboxylic acids (A2-2), some of the carboxyl groups may form a salt (such as a metal salt), but in the present invention, the carboxyl groups (all the carboxyl groups) are usually a salt. In many cases, a carboxylic acid that does not form a carboxylic acid is used.

Moreover, as long as it has a carboxyl group, carboxylic acid (A2-2) has functional groups other than a carboxyl group (or a coordination group with respect to a metal compound or a metal nanoparticle), for example, a halogen atom and a hetero atom. Group {for example, a group having an oxygen atom [hydroxyl group, alkoxy group (for example, C _1-6 alkoxy group such as methoxy group, ethoxy group, propoxy group, butoxy group), formyl group, carbonyl group, ester group, etc.], A group having a sulfur atom [for example, thio group, thiol group, thiocarbonyl group, alkylthio group (C _1-4 alkylthio group such as methylthio group, ethylthio group, etc.), sulfo group, sulfamoyl group, sulfinyl group (—SO ₂ — ) Etc.] etc.}. Carboxylic acids (A2-2) may have these functional groups alone or in combination of two or more.

Representative carboxylic acids (A2-2) include, for example, C _1-3 monocarboxylic acid [eg, C _1-3 aliphatic monocarboxylic acid (eg, formic acid, acetic acid, propionic acid, acrylic acid, etc.)] C _2-3 polycarboxylic acid (oxalic acid, propanedioic acid, etc.), C _2-3 hydroxycarboxylic acid (or oxycarboxylic acid, glycolic acid, lactic acid, etc.) and the like. These carboxylic acids may be anhydrides, hydrates, and the like.

  Carboxylic acids (A2-2) may be used alone or in combination of two or more.

Of these carboxylic acids (A2-2), C _1-3 saturated aliphatic monocarboxylic acids such as acetic acid and propionic acid are preferable, and propionic acid is particularly preferable.

  The pKa value of the carboxylic acids (A2-2) may be, for example, 1 or more (for example, about 1 to 10), preferably 2 or more (for example, about 2 to 8).

(A2-3) Amines having a hydroxyl group As the amines having a hydroxyl group, alkanolamines are usually used. Examples of the alkanolamines include monoalkanolamines [for example, monoethanolamine (2-aminoethyl alcohol), monopropanolamine, monoisopropanolamine, 2-amino-2-methyl-1-propanol, 2-amino-2. - such as mono C _2-6 alkanolamines such as methyl-1,3-propanediol, dialkanolamine (e.g., diethanolamine, di-propanolamine, and di C _2-6 alkanolamines such as diisopropanolamine), trialkanolamines Amines (for example, tri-C _2-6 alkanolamines such as triethanolamine, tripropanolamine, triisopropanolamine), alkyl alkanolamines (N—C _1-3 alkylmono such as N-methylethanolamine) C _2-6 alkanolamines, N-N-C _1-3 alkyl di C _2-6 alkanolamines such as methyldiethanolamine, N, N-dimethyl-ethanol-di C _1-3 alkyl mono- or di-C _2-6 alkanol such as amines Amine), or these ethylene oxide adducts. These alkanolamines can be used alone or in combination of two or more.

Among these amines, C _2-6 alkanolamines (for example, mono-C _2-6 alkanolamines such as monoethanolamine and monopropanolamine, di- _C2-3 alkanolamines such as diethanolamine, and triethanolamine) are included. Mono _C2-3 alkanolamines such as monoethanolamine are particularly preferred.

  In the metal colloid particles, the ratio of protective colloid (A2) [total amount of amines (A2-1), carboxylic acids (A2-2) and amines (A2-3)] is 100 masses of metal nanoparticles (A1). Part to 100 parts by weight (for example, 0.5 to 80 parts by weight), preferably 1 to 60 parts by weight (for example, 1.5 to 50 parts by weight), more preferably 3 to 100 parts by weight. About 50 mass parts (for example, 5-40 mass parts) may be sufficient.

  In the metal colloid particles, the ratio of the amines (A2-1) is, for example, 0.01 to 70 parts by mass (for example, 0.1 to 50 parts) with respect to 100 parts by mass of the metal nanoparticles (A1). Part by mass), preferably 0.5 to 40 parts by mass (for example, 1 to 30 parts by mass), more preferably about 1.5 to 20 parts by mass (for example, 2 to 15 parts by mass).

  The ratio of carboxylic acid (A2-2) is 0.01-50 mass parts (for example, 0.05-30 mass parts) with respect to 100 mass parts of metal nanoparticles (A1), for example, Preferably it is 0. 0.1-30 mass parts (for example, 0.5-20 mass parts), More preferably, about 1-15 mass parts (for example, 2-10 mass parts) may be sufficient.

  The ratio of the amines (A2-3) is, for example, 0.01 to 40 parts by mass (for example, 0.05 to 30 parts by mass), preferably 0 with respect to 100 parts by mass of the metal nanoparticles (A1). It may be about 1 to 25 parts by mass (for example, 0.3 to 20 parts by mass), more preferably about 0.5 to 10 parts by mass (for example, 1 to 5 parts by mass). Moreover, the ratio of amines (A2-3) is 1-35 mass parts with respect to a total of 100 mass parts of amines (A2-1) and carboxylic acids (A2-2), Preferably it is 3-30. It may be about 5 to 25 parts by mass (particularly 8 to 20 parts by mass). Furthermore, the ratio (mass ratio) to the amines (A2-1) is also important from the point of transferability of the intaglio, for example, amines (A2-1) / amines (A2-3) = 99/1 50/50, preferably 95/5 to 60/40, more preferably about 90/10 to 70/30.

  In addition, about the ratio of amines (A2-3), what is necessary is just the said range as a ratio of the whole particle | grains containing a metal colloid particle (A). That is, the ratio of amines (A2-3) may be within the above range as an average of the protective colloid of all metal colloid particles, and the individual metal nanoparticles may be out of the above range. Specifically, in the mixture of particles containing amines (A2-3) in the protective colloid and particles not containing amines (A2-3) in the protective colloid, the proportion of all particles in the protective colloid Should just be in the said range.

  In the metal colloidal particles, the ratio of amines [total of amines (A2-1) and amines (A2-3)] to carboxylic acids (A2-2) is the former / the latter (mass ratio) = 99/1. It may be about 1/99, preferably 95/5 to 10/90, more preferably about 90/10 to 30/70 (especially 85/15 to 50/50).

  In addition, the metal colloid particle of this invention should just contain the said protective colloid (A2) at least as a protective colloid, and may contain the other protective colloid. Other protective colloids may be inorganic compounds, but are usually organic compounds.

Examples of the organic compound include amines including amines exemplified in the protective colloid (A2), carboxylic acids including carboxylic acids exemplified in the protective colloid (A2), and organic compounds containing oxygen atoms {for example, ketones [ For example, alkanones, cycloalkanones, diketones (β-diketones such as acetylacetone)], aldehydes (C _6-20 aliphatic aldehydes such as caprylaldehyde, laurylaldehyde, palmitoaldehyde, stearylaldehyde), etc. }, Organic compounds containing sulfur atoms [for example, sulfoxides, sulfonic acids (eg, arene sulfonic acids such as alkane sulfonic acid, benzene sulfonic acid, toluene sulfonic acid, etc.)] and the like. These other protective colloids may be used alone or in combination of two or more as long as they are different from the protective colloid (A2).

  Among these organic compounds, a combination of an amine having 1 to 10 carbon atoms having no hydroxyl group and a carboxylic acid having 1 to 3 carbon atoms is preferable. The ratio of the protective colloid to the metal nanoparticles and the ratio of the amine having 1 to 10 carbon atoms having no hydroxyl group and the carboxylic acid having 1 to 3 carbon atoms are the same as those in the protective colloid (A2).

  The proportion of the other protective colloid is, for example, 1 to 1000 parts by weight, preferably 10 to 500 parts by weight, more preferably 30 to 300 parts by weight (particularly 50 to 250 parts) with respect to 100 parts by weight of the protective colloid (A2). Part by mass).

(B) Dispersion medium The dispersion medium is not particularly limited as long as it is a solvent that generates sufficient viscosity in the paste by combining with the metal colloid particles (or metal nanoparticles), and a general-purpose solvent can be used. Examples of the dispersion medium (dispersion solvent) include alcohols {for example, aliphatic alcohols (for example, heptanol, octanol (1-octanol, 2-octanol, etc.), decanol (1-decanol, etc.), lauryl alcohol, tetradecyl. Saturated or unsaturated C _6-30 aliphatic alcohols such as alcohol, cetyl alcohol, 2-ethyl-1-hexanol, octadecyl alcohol, hexadecenol, oleyl alcohol, preferably saturated or unsaturated C _8-24 aliphatic alcohols), Alicyclic alcohols [eg, cycloalkanols such as cyclohexanol; terpene alcohols such as terpineol and dihydroterpineol (eg, monoterpene alcohol)], araliphatic alcohols (eg, benzyl alcohol) , Phenethyl alcohol, etc.), polyhydric alcohols (ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and other (poly) C _2-4 alkylene glycols and other glycols; glycerin and the like having three or more hydroxyl groups Polyhydric alcohol, etc.}, glycol ethers (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene Glycol monomethyl ether, dipropylene glycol monomethyl ether, tripro (Poly) alkylene glycol monoalkyl ethers such as pyrene glycol butyl ether; (poly) alkylene glycol monoaryl ethers such as 2-phenoxyethanol), glycol esters (eg, (poly) alkylene glycol acetates such as carbitol acetate), Glycol ether esters (for example, (poly) alkylene glycol monoalkyl ether acetates such as ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate), carbonization Hydrogens [eg, aliphatic hydrocarbons (eg, Saturated or unsaturated aliphatic hydrocarbons such as tradecane, octadecane, heptamethylnonane, tetramethylpentadecane), aromatic hydrocarbons (eg, toluene, xylene, etc.)], esters (eg, benzyl acetate, isoacetate) And polar solvents (solvents having a polar group) such as borneol, methyl benzoate, ethyl benzoate and the like. These solvents may be used alone or in combination of two or more.

Typical dispersion media include aliphatic alcohols (eg, saturated or unsaturated C _6-30 aliphatic alcohols such as 2-ethyl-1-hexanol, octanol, decanol, preferably saturated or unsaturated C _6-20 fats). And polar solvents such as alicyclic alcohols [for example, terpene alcohols such as terpineol and dihydroterpineol (for example, monoterpene alcohol)].

  The boiling point of the dispersion medium (in the case of a mixed solvent, the boiling point of each solvent) varies depending on the use of the metal nanoparticle paste, but is preferably 100 ° C. or higher (eg, about 100 to 300 ° C.), For example, even if it is about 100-400 degreeC (for example, 120-380 degreeC), Preferably it is about 130-370 degreeC (for example, 150-350 degreeC), More preferably, it is about 170-320 degreeC (for example, 180-300 degreeC). It may be about 180 to 270 ° C. (for example, 185 to 250 ° C.).

  In the metal nanoparticle paste, the ratio of the dispersion medium is, for example, 0.1 to 100 parts by weight, preferably 1 to 80 parts by weight, more preferably 2 to 50 parts by weight with respect to 100 parts by weight of the metal colloid particles. In particular, it may be about 3 to 30 parts by mass (for example, 5 to 20 parts by mass).

  For metal nanoparticle pastes, conventional additives such as binder resins (hydrophilic polymers such as polyvinyl alcohol and polyethylene glycol), hue improvers, gloss imparting agents, metal corrosion inhibitors, stable Agent, surfactant or dispersant (anionic surfactant, cationic surfactant, nonionic surfactant, amphoteric surfactant, etc.), fluidity improver (amines such as ethylenediamine and / or 2-ethyl) Carboxylic acids such as hexanoic acid), dispersion stabilizers, thickeners or viscosity modifiers, humectants, thixotropic agents, antifoaming agents, bactericides, fillers and the like may be included. These additives can be used alone or in combination of two or more. The metal nanoparticle paste preferably does not contain these additives from the viewpoint of conductivity and low-temperature sintering, and particularly preferably does not substantially contain a binder resin (organic binder).

  In the metal nanoparticle paste, the ratio of the metal nanoparticles (A1) is, for example, 40% by mass or more (for example, about 45 to 95% by mass), preferably 50% by mass or more (for example, about 55 to 90% by mass), More preferably, it may be 60 mass% or more (for example, about 65 to 85 mass%), and particularly 70 mass% or more (for example, about 70 to 90 mass%).

  Further, the viscosity of the metal nanoparticle paste varies depending on the application and the printing method to be applied, but is usually 0.5 Pa · s or more (for example, 1 to 400 Pa · s) at 25 ° C., preferably 3 Pa · s. Above (for example, 5 to 300 Pa · s), more preferably 10 to 200 Pa · s, especially about 15 to 100 Pa · s (for example, 20 to 80 Pa · s), usually about 10 to 70 Pa · s. There may be. This viscosity is a value measured using a general-purpose viscometer (for example, a B-type viscometer or an E-type viscometer).

[Production Method of Metal Nanoparticle Paste]
The metal nanoparticle paste of the present invention is not particularly limited as long as the metal nanoparticle paste having the above-described configuration can be obtained. Usually, the metal colloidal particles (A) are obtained by dispersing them in the dispersion medium (B). be able to.

  The metal colloid particles (A) (or dispersions thereof) can be prepared by a conventional method, for example, by applying a metal compound corresponding to the metal nanoparticles (A1) to the protective colloid (A2) (and the other protection if necessary). Colloid) and a reducing agent in the presence of a reducing agent.

  Examples of the metal compound corresponding to the metal nanoparticle (A1) include metal oxide, metal hydroxide, metal sulfide, metal halide, metal acid salt [metal inorganic acid salt (sulfate, nitrate, perchloric acid). Oxo acid salts such as salts), metal organic acid salts (such as acetates), and the like]. In addition, the form of the metal salt may be any of a single salt, a double salt, or a complex salt, and may be a multimer (for example, a dimer). These metal compounds can be used alone or in combination of two or more. Among these metal compounds, metal halides, metal acid salts [metal inorganic acid salts (such as sulfates, nitrates, perchlorates, etc.), metal organic acid salts (such as acetates), etc.] Often used. These metal compounds may be used by dissolving or dispersing in a solvent (for example, in the form of a solution of an aqueous solvent such as an aqueous solution).

  Examples of the reducing agent include conventional components such as sodium borohydride (sodium borohydride, sodium cyanoborohydride, sodium triethylborohydride, etc.), lithium aluminum hydride, hypophosphorous acid or a salt thereof (sodium). Salt), boranes (diborane, dimethylamine borane, etc.), hydrazines (hydrazine, etc.), formalin, organic acids (citric acid, tartaric acid, ascorbic acid, etc.) and the like. These reducing agents can be used alone or in combination of two or more.

  The amount of the reducing agent used is 1 to 30 mol (for example, 1.2 to 20 mol), preferably 1.5 to 15 mol, based on 1 equivalent (or 1 mol) of the metal compound in terms of metal atom. Preferably, it may be about 2 to 10 mol, and usually about 1 to 5 mol.

  The reduction reaction can be performed by a conventional method, for example, at a temperature of about 10 to 75 ° C. (for example, about 15 to 50 ° C., preferably about 20 to 35 ° C.). The atmosphere of the reaction system may be air, an inert gas (such as nitrogen gas), or an atmosphere containing a reducing gas (such as hydrogen gas). In addition, the reaction may be usually performed under stirring (or while stirring).

  The reaction solvent may be the aforementioned dispersion medium (B) constituting the final metal nanoparticle paste, or a solvent different from the dispersion medium (B) constituting the metal nanoparticle paste. It may be a mixed solvent of these. The reaction solvent can be selected according to the type of the protective colloid. For example, when the protective colloid is a water-soluble compound, the reaction solvent is often composed of a polar solvent such as water, and a hydrophobic compound. In some cases, the reaction solvent is often composed of a hydrophobic solvent.

In addition to the dispersion medium, the reaction solvent is a hydrophobic solvent [for example, hydrocarbons (for example, aliphatic hydrocarbons such as hexane, heptane, trimethylpentane, octane, decane, dodecane, and tetradecane; alicyclic such as cyclohexane) Hydrocarbons; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and trichloroethane), esters (such as methyl acetate and ethyl acetate), ketones (such as methyl ethyl ketone and methyl isobutyl ketone), Ethers (diethyl ether, dipropyl ether, etc.)], polar solvents [water, alcohols (C _1-4 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, etc.), aliphatic polyhydric alcohols (ethylene glycol) , Polyethylene grease Coal, glycerin, etc.), ketones (acetone, etc.), ethers (dioxane, tetrahydrofuran, etc.), organic carboxylic acids (acetic acid, etc.) and the like. These solvents may be used alone or in combination of two or more. The reaction solvent may usually be composed of at least a hydrophobic solvent (a hydrophobic solvent that is not the dispersion medium).

  In addition, the density | concentration of the said metal compound in a reaction solvent is 5 mass% or more (for example, 6-50 mass%) in conversion of the mass of a metal, for example, Preferably it is 8 mass% or more (for example, 9-40 mass%). More preferably, it may be a high concentration of 10% by mass or more (for example, 12 to 30% by mass), usually about 5 to 30% by mass.

  The pH of the reaction system may be adjusted according to the type of reaction solvent.

  The pH is adjusted by a conventional method, for example, an acid (an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or perchloric acid, an organic acid such as formic acid, acetic acid, propionic acid or benzoic acid), an alkali [sodium hydroxide, Inorganic bases such as sodium hydrogen carbonate and ammonia, and bases such as amines (for example, organic bases such as tertiary amines such as alkyl amines) can be used.

  By the reaction (reduction reaction) as described above, the metal colloid particles (A) can be prepared in the form of a dispersion in which the metal colloid particles (A) are dispersed in the reaction solvent. In addition, after completion | finish of a reductive reaction, you may refine | purify a reaction liquid mixture by a conventional method (For example, centrifugation; Filtration processing, such as filtration by a membrane filter, ultrafiltration, etc.).

  The metal nanoparticle paste can be prepared by concentrating unnecessary solvent components from the dispersion when the solvent containing the dispersion medium (B) is used as the reaction solvent. It can be prepared by dispersing (redispersing) the metal colloidal particles (A) separated from the dispersion in the dispersion medium (B).

  Separation of the metal colloid particles (A) from the dispersion can be performed by a conventional method, for example, by separating and removing the reaction solvent from the dispersion. For removal of the reaction solvent, a conventional concentration operation or the like can be used. The removal of the reaction solvent may be performed in the presence of the dispersion medium (B) using the difference in boiling point between the reaction solvent and the dispersion medium (B) (that is, removal of the reaction solvent and the dispersion medium). (B) may be dispersed in the same system). For example, the reaction solvent may be removed from a mixture obtained by mixing the dispersion medium (B) with the dispersion.

  The amount of the dispersion medium (B) used can be appropriately adjusted so as to obtain a desired viscosity, and may be appropriately selected from the same range as described above. The viscosity may be adjusted by mixing other solvent in addition to the dispersion medium and removing the other solvent.

  Furthermore, the metal nanoparticle paste of the present invention contains a first paste not containing amines (A2-3) having a hydroxyl group as a protective colloid and amines (A2-3) having a hydroxyl group as a protective colloid. The second paste may be included. The method of preparing by mixing the first paste and the second paste is effective, for example, when adjusting the concentration of amines having a hydroxyl group according to the required printability.

  About the ratio of the C1-C10 amines and C1-C3 carboxylic acids which do not have a hydroxyl group in the 1st and 2nd paste, it can select from the range in the said metal colloid particle (A).

  The ratio of the amine (A2-3) having a hydroxyl group in the second paste is, for example, 0.05 to 50 parts by mass, preferably 0.1 to 100 parts by mass of the metal nanoparticles (A1). -30 mass parts, More preferably, about 0.5-20 mass parts (for example, 1-10 mass parts) may be sufficient. Furthermore, the ratio of amines having a hydroxyl group (A2-3) is the sum of amines having 1 to 10 carbon atoms (A2-1) having a hydroxyl group and carboxylic acids having 1 to 3 carbon atoms (A2-2). For example, 5-100 mass parts with respect to 100 mass parts, Preferably it is 10-80 mass parts, More preferably, about 30-70 mass parts (especially 35-50 mass parts) may be sufficient.

  The ratio (mass ratio) of both pastes is such that the ratio of amines having hydroxyl groups (A2-3) in all metal colloidal particles is within the above range, for example, in terms of solid content, 2 paste = can be selected from the range of about 1/99 to 99/1, for example, 10/90 to 90/10, preferably 20/80 to 80/20, more preferably about 30/70 to 70/30. is there.

[Use of metal nanoparticle paste]
The metal nanoparticle paste of the present invention can be used for various applications. For example, the metal nanoparticle paste of the present invention is useful as a paste for forming a metal film (particularly a conductive film). In particular, since the metal nanoparticle paste of the present invention contains metal nanoparticles at a high concentration and can be sintered at a relatively low temperature, a predetermined pattern (circuit) among metal films (continuous film, sintered film). It is suitable as a paste for forming a pattern, particularly a conductive pattern. Hereinafter, a method for forming a pattern using the metal nanoparticle paste will be described in detail.

  In such a method, a pattern (coating layer) is usually formed (drawn) on the substrate by the metal nanoparticle paste (or coating of the metal nanoparticle paste), and the formed pattern (drawing pattern) is baked. By processing, a sintered pattern (sintered film, metal film, sintered body layer, conductor layer) can be formed.

  It does not specifically limit as a base material (or board | substrate), According to a use, it can select suitably. The material constituting the substrate may be an inorganic material or an organic material. Examples of inorganic materials include glasses (soda glass, borosilicate glass, crown glass, barium-containing glass, strontium-containing glass, boron-containing glass, low alkali glass, alkali-free glass, crystallized transparent glass, silica glass, and quartz glass. And heat-resistant glass), metal oxides (alumina, sapphire, zirconia, titania, yttrium oxide, etc.). Examples of the organic material include polymethyl methacrylate resin, styrene resin, vinyl chloride resin, polyester resin [including polyalkylene arylate resin (polyethylene terephthalate, etc.), polyarylate resin and liquid crystal polymer], Examples include polyamide resins, polycarbonate resins, polysulfone resins, polyethersulfone resins, polyimide resins, cellulose derivatives, and fluororesins. Since these materials undergo a baking process, they are highly heat-resistant materials, such as inorganic materials, engineering plastics (for example, aromatic polyester resins (including polyarylate resins), polyimide resins, polysulfone resins, etc.) A liquid crystal polymer, a fluororesin and the like are preferable. In particular, in the present invention, since it can be sintered at low temperature, a pattern can be formed even on a base material made of resin. In addition, the base material may be surface-treated.

  What is necessary is just to select the thickness of a base material (or board | substrate) suitably according to a use, for example, 0.001-10 mm, Preferably it is 0.01-5 mm, More preferably, it is 0.05-3 mm (especially 0.1-3 mm). 1 mm) or so.

  The drawing method (or printing method) for drawing the pattern (coating layer) is not particularly limited as long as it is a pattern forming printing method. For example, a screen printing method, an ink jet printing method, an intaglio printing method (for example, Gravure printing method), offset printing method, intaglio offset printing method, flexographic printing method and the like. In the present invention, the concentration of the metal nanoparticles can be easily controlled by the dispersion medium, and appropriate fluidity can be secured, and the properties such as viscosity or spinnability are excellent, so that scraping by a doctor blade and transfer by a silicone blanket are possible. This is particularly useful for the intaglio offset printing method that requires the above.

  The average thickness of the coating layer (or sintered pattern) may be, for example, about 0.5 to 20 μm, preferably 0.6 to 15 μm, and more preferably about 0.8 to 10 μm (particularly 1 to 5 μm). In the present invention, since a paste containing metal nanoparticles at a high concentration is used, such a thick film on the order of microns can be formed efficiently.

  The line width (minimum line width) of the coating layer (or sintered pattern) is, for example, 1 to 50 μm, preferably 3 to 40 μm, and more preferably about 5 to 30 μm. In particular, in the present invention, fine firing with a minimum line width of 30 μm or less (for example, 1 to 30 μm, preferably 2 to 25 μm), preferably a minimum line width of about 25 μm or less (for example, 1 to 23 μm, preferably 2 to 20 μm). Even a bonded pattern can be formed efficiently. The ratio between the minimum line width and the average thickness of the coating layer (or sintered pattern) is the former / the latter = 1/20 to 1/2, preferably 1/18 to 1/3, and more preferably 1/15. It may be about １ ／.

  The baking treatment can usually be performed by heating the pattern at a predetermined baking temperature (or baking or heat treatment). The firing temperature is not particularly limited as long as the metal nanoparticles can be fused to form a continuous film, and can be appropriately selected. In particular, since the metal nanoparticle paste of the present invention sinters even at a relatively low temperature, the firing temperature is 350 ° C. or less (eg, about 50 to 350 ° C.), preferably 70 to 320 ° C., more preferably About 80-300 degreeC (for example, 100-280 degreeC) may be sufficient, and about 100-350 degreeC may be sufficient normally. In particular, in the present invention, even at a low temperature of 150 ° C. or less [eg, 40 to 150 ° C., preferably 45 to 145 ° C. (eg 50 to 140 ° C.), more preferably 55 to 135 ° C., particularly about 60 to 130 ° C.]. Sinterable. Therefore, a metal film or pattern can be formed on a resin substrate or the like, and the application range is wide.

  The firing time (heating time) may be, for example, 10 minutes to 6 hours, preferably 15 minutes to 5 hours, more preferably about 20 minutes to 3 hours, depending on the firing temperature and the like.

  A sintered pattern (sintered body layer) is thus formed. The sintered pattern has high conductivity when conductive metal particles are used as the metal nanoparticles. Note that the thickness and line width of the sintered pattern are in the same ranges as described above.

  Since the metal nanoparticle paste of the present invention contains metal nanoparticles at a high concentration, it is useful, for example, as a paste for forming a metal film (sintered film). In particular, it does not contain metal fillers or organic binders and can be sintered at low temperatures, so it has excellent printability. In particular, even with printing methods such as intaglio offset printing, fine patterns (circuit or wiring patterns) can be efficiently produced. Can be formed.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
2.5 g of silver nitrate, 4.9 g of n-octylamine and 2.0 g of propionic acid were added to 1.0 liter of trimethylpentane, and the mixture was stirred and dissolved. To this mixed solution, 1.0 liter of a propanol solution containing 0.03 mol / liter sodium borohydride was added dropwise over 1 hour to reduce silver. Furthermore, it stirred for 3 hours and obtained the black liquid. After the obtained black liquid was concentrated by an evaporator, 2.0 liters of methanol was added thereto to form a brown precipitate, and then the precipitate was collected by suction filtration. The resulting precipitate was redispersed in trimethylpentane, filtered and dried to obtain silver colloidal particles as a black solid. According to the transmission electron microscope (TEM), the number average particle diameter of the core part of the obtained silver nanoparticles is 3.5 nm. According to the dynamic light scattering particle size measurement (DLS), the silver colloid containing the protective colloid The number average particle size of the entire particles was 6.3 nm.

  2.0 g of the obtained silver colloid particles and 0.3 g of 1-ethylhexanol were mixed in a mortar to prepare a first silver nanoparticle paste. The obtained paste was dark blue and highly fluid. The viscosity of the first silver nanoparticle paste (E-type viscometer, measured 5 times / minute at 25 ° C.) was 17 Pa · s, and the metal content was 73.7% by mass.

  Separately from this first paste, 2.5 g of silver nitrate, 3.9 g of n-octylamine, 1.8 g of 2-aminoethanol, and 1.0 g of propionic acid are added to 1.0 liter of trimethylpentane, and mixed by stirring to dissolve. did. To this mixed solution, 1.0 liter of a propanol solution containing 0.03 mol / liter sodium borohydride was added dropwise over 1 hour to reduce silver. Furthermore, it stirred for 3 hours and obtained the black liquid. After the obtained black liquid was concentrated by an evaporator, 2.0 liters of methanol was added thereto to form a brown precipitate, and then the precipitate was collected by suction filtration.

  2.7 g of the obtained precipitate (silver colloid particles) and 0.3 g of terpionel (manufactured by Wako Pure Chemical Industries, Ltd., isomer mixture) were mixed in a mortar and stirred for about 1 hour to obtain the second silver. A nanoparticle paste was prepared. The obtained paste was black purple and low in fluidity. This second silver nanoparticle paste had a viscosity of 23 Pa · s and a metal content of 74.0% by mass.

  Next, the first paste and the second paste were mixed at a mass ratio of first paste / second paste = 2/1 to prepare a mixed paste. The viscosity of the mixed paste was 15 Pa · s, and the metal content was 73.8% by mass.

  Using the obtained mixed paste, a fine line pattern was printed (patterned) by intaglio offset printing on a polyethylene terephthalate substrate (thickness: 175 μm, manufactured by Teijin DuPont Films, Inc., “Teijin Tetron Film HS175”), and then 120 ° C. in an oven. Heat treatment was carried out at 30 ° C. for 30 minutes. No disconnection was seen in the printed fine lines. The line width of the fine wire was 12 μm, the film thickness was 1.3 μm, and the volume resistivity was 10 μΩ · cm.

Example 2
The first paste and the second paste obtained in Example 1 were mixed at a mass ratio of first paste / second paste = 1/1 to prepare a mixed paste. The viscosity of the mixed paste was 16 Pa · s, and the metal content was 73.9% by mass.

  Using the obtained mixed paste, a fine line pattern was printed (patterned) on the polyethylene terephthalate substrate by intaglio offset printing, and heat-treated in an oven at 120 ° C. for 30 minutes. No disconnection was seen in the printed fine lines. The line width of the fine wire was 15 μm, the film thickness was 1.4 μm, and the volume resistivity was 12 μΩ · cm.

Comparative Example 1
Using the first paste obtained in Example 1, intaglio offset printing was attempted on a polyethylene terephthalate substrate, but the paste was not transferred to the blanket.

Comparative Example 2
Using the second paste obtained in Example 1, an intaglio offset printing was attempted on a polyethylene terephthalate substrate. As a result, a fine line pattern could be printed. It was transferred and it was not possible to print clean fine lines.

Claims (10)

  Metal nanoparticle paste comprising metal colloid particles (A) formed of metal nanoparticles (A1) and protective colloid (A2) covering the metal nanoparticles (A1), and a dispersion medium (B) of the metal colloid particles The protective colloid (A2) has a hydroxyl group, which is a C1-C10 amine (A2-1), a C1-C3 carboxylic acid (A2-2) having no hydroxyl group, and a hydroxyl group. In the protective colloid comprising the amines (A2-3) and constituting all metal colloidal particles contained in the paste, the proportion of amines having a hydroxyl group is 1 to 10 carbon atoms having no hydroxyl group. The metal nanoparticle paste which is 1-35 mass parts with respect to a total of 100 mass parts of amines and C1-C3 carboxylic acids. The amine (A2-1) is a mono C _4-10 alkylamine, the carboxylic acid (A2-2) is a C _1-3 saturated aliphatic monocarboxylic acid, and the amine (A2-3) is C _{2. -6} alkanolamine, and the ratio of the 1 to 10 carbon amines having no hydroxyl group and amines having a hydroxyl group (mass) in the protective colloid constituting all metal colloid particles contained in the paste The metal nanoparticle paste according to claim 1, wherein the ratio is the former / the latter = 99/1 to 50/50.   The metal nanoparticle paste according to claim 1 or 2, wherein the metal constituting the metal nanoparticles (A1) is a simple silver, and the average particle diameter of the metal nanoparticles (A1) is 10 nm or less.   The proportion of the protective colloid (A2) is 1 to 60 parts by mass with respect to 100 parts by mass of the metal nanoparticles (A1), and the total amount of amines (A2-1) and amines (A2-3) The metal nanoparticle paste according to any one of claims 1 to 3, wherein a ratio with the acids (A2-2) is the former / the latter (mass ratio) = 85/15 to 50/50.   The metal nanoparticle paste according to any one of claims 1 to 4, wherein the dispersion medium (B) is a polar solvent having a boiling point of 100 to 300C.   A first paste / first paste containing no amines (A2-3) as a protective colloid and a second paste containing amines (A2-3) as a protective colloid in terms of solid content. The metal nanoparticle paste according to claim 1, which is contained at a ratio (mass ratio) of 2 paste = 10/90 to 90/10.   The pattern formation method which forms a sintered pattern by forming an electrode or a wiring pattern in the base material with the metal nanoparticle paste in any one of Claims 1-6, and baking this pattern.   The pattern forming method according to claim 7, wherein an electrode or a wiring pattern is formed by intaglio offset printing.   The pattern formation method of Claim 7 or 8 which uses a resin-made base material as a board | substrate and performs baking processing at the baking temperature of 150 degrees C or less.   The pattern forming method according to claim 7, wherein a sintered pattern having a minimum line width of 20 μm or less is formed.