JP5632176B2 - Laminated body, conductive substrate using the laminated body, and method for producing the same - Google Patents

Description

  The present invention relates to a laminate using a conductive paste containing conductive particles and a binder resin, a conductive substrate and a precursor thereof, and a method for producing a conductive substrate.

  Currently, conductive paste such as silver paste is used for forming electrodes and circuits of electronic components and the like. These pastes are pastes in which a binder resin such as an epoxy resin is dispersed in a solvent in addition to metal powder. After forming this paste in a predetermined pattern by printing, the organic components are removed by heating to form particles. At the same time, a softened resin or the like forms an adhesion layer at the interface between the base material and the conductor to ensure the adhesion.

  As an electrically conductive paste using such a resin binder, for example, Japanese Patent Application Laid-Open No. 2002-109957 (Patent Document 1) discloses conductive particles (A) and a solvent having a surface tension of 30 to 50 mN / m ( A conductive paste containing B) and a binder resin (C) is disclosed. The purpose of this conductive paste is to improve the separation of the paste by using a solvent having a high surface tension, reduce bleeding, and create a high-definition wiring pattern. In this document, examples of the binder resin include a thermosetting type such as an epoxy resin and a baking type such as a (meth) acrylic resin. The amount of the epoxy resin added is 100 parts by mass of the conductive particles (A). It is described that the range of 1 to 20 parts by mass is preferable.

  However, in order to form a conductive layer having high adhesion to the substrate using a paste containing a binder resin, it is necessary to increase the ratio of the binder resin, but when the ratio of the binder resin increases, A large amount of resin binder remains after firing, and the resistivity increases.

JP 2002-109957 A (Claim 1, paragraphs [0018] [0022] [0039])

  Accordingly, an object of the present invention is to provide a conductive substrate and a precursor thereof capable of forming a conductive layer having high adhesion to both organic and inorganic substrates and low resistivity even when fired at a low temperature. And providing a method for producing a conductive substrate.

  Another object of the present invention is to provide a conductive base material capable of forming a conductive film having high adhesion to the base material and low resistivity under severe conditions such as high temperature and high humidity even if the ratio of the binder resin is small. It is in providing the manufacturing method and the electroconductive base material obtained by the manufacturing method.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors formed an adhesive layer made of a thermoplastic resin on a base material, and then applied and baked a conductive paste containing a binder resin. The inventors have found that even when baked at a low temperature, a conductive film having high adhesion and low resistivity can be formed on both organic and inorganic substrates, and the present invention has been completed.

  That is, the laminate of the present invention is a laminate in which a coating film is formed on a substrate via an adhesive layer, the adhesive layer is composed of a thermoplastic resin, and the coating film is electrically conductive. The conductive paste includes conductive particles, a binder resin, and a dispersion medium. The thermoplastic resin may contain an aqueous polyester resin. The adhesive layer may have a thickness of about 0.1 to 10 μm. The substrate may be a substrate made of polyester resin (for example, polyethylene naphthalate resin), polycarbonate resin or polyimide resin, or a substrate made of glass, alumina, silicon or carbon. May be. The conductive particles may be metal colloid particles and metal fillers. The metal colloidal particles may be composed of silver nanoparticles and a dispersing agent in which an aggregating aid and a polymer dispersing agent are combined. The metal filler may be a silver filler. The binder resin may be an epoxy resin. About 0.1-5 mass parts may be sufficient as the ratio of the said binder resin with respect to 100 mass parts of electroconductive particle. When the substrate is composed of an organic material, the ratio of the binder resin may be about 0.1 to 2 parts by mass with respect to 100 parts by mass of the conductive particles.

  The present invention also includes a method for producing a conductive substrate in which the laminate is fired at 150 to 300 ° C. When the substrate is composed of an organic material, the firing temperature may be about 150 to 200 ° C. Further, the present invention includes a conductive substrate obtained by this method.

  In the laminate of the present invention, the conductive paste is laminated on the organic and inorganic base materials via the adhesive layer composed of the thermoplastic resin. A conductive layer having high adhesion to the material and low resistivity can be formed. Furthermore, even if the ratio of the binder resin is small, a conductive film having high adhesion and low resistivity can be formed on both organic and inorganic substrates under severe conditions such as high temperature and high humidity.

  The laminate of the present invention comprises a base material, an adhesive layer formed on the base material, and a coating film (conductive paste) formed on the adhesive layer. It is a precursor.

[Base material]
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 organic material (organic material) or an inorganic material (inorganic material).

  Examples of the organic material include polymethyl methacrylate resin, styrene resin, vinyl chloride resin, polyester resin [polyalkylene arylate resin (polyalkylene arylate resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. Etc.), polyamide resins, polycarbonate resins, polysulfone resins, polyethersulfone resins, polyimide resins, cellulose derivatives, fluororesins, and the like.

  Since these materials go through a baking process, they are highly heat-resistant materials, for example, inorganic materials such as semiconductors, glasses, and metals, engineering plastics [for example, aromatic polyester resins (polyalkylene arylate resins such as polyethylene naphthalate, etc.) , Polyarylate resins, etc.), polycarbonate resins, polyimide resins, polysulfone resins, etc.], plastics such as liquid crystal polymers and fluororesins are preferred. Of these, polyethylene naphthalate resin, polyimide resin, and polycarbonate resin are preferable from the viewpoint of heat resistance, and in particular, when used in highly transparent applications such as solar cells, transparency is impaired by firing. Materials such as polyethylene naphthalate resin and polycarbonate resin are preferable.

  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. ), Ceramics {metal oxide (silicon oxide, quartz, alumina or aluminum oxide, zirconia, sapphire, ferrite, titania or titanium oxide, zinc oxide, niobium oxide, mullite, beryllia, etc.), metal nitride (nitriding) Aluminum, silicon nitride, boron nitride, carbon nitride, titanium nitride, etc.), metal carbide (silicon carbide, boron carbide, titanium carbide, tungsten carbide, etc.), metal boride (titanium boride, zirconium boride, etc.), metal double oxidation [Titanate metal salt Barium, strontium titanate, lead titanate, niobium titanate, calcium titanate, magnesium titanate, etc.), zirconate metal salts (barium zirconate, calcium zirconate, lead zirconate, etc.) etc.], etc.], metal (Aluminum, copper, gold, silver, etc.), carbon materials (carbon such as amorphous carbon, graphite, etc.) and semiconductors (conductors formed of conductors, semiconductors, insulators, etc.).

  The surface of the base material is subjected to oxidation treatment [surface oxidation treatment such as discharge treatment (corona discharge treatment, glow discharge, etc.), acid treatment (chromic acid treatment, etc.), ultraviolet irradiation treatment, wrinkle treatment, etc., surface unevenness treatment (solvent Surface treatment such as treatment, sandblast treatment, etc.).

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

[Adhesive layer]
The adhesive layer is made of a thermoplastic resin, can improve the adhesion of the metal particles to the base material, and can firmly fix the base material and the conductive layer. In the present invention, by forming an adhesive layer made of a thermoplastic resin on the base material, the thermoplastic resin follows the shrinkage deformation when the conductive paste is baked, and a gap generated between the substrate and the substrate. And a high contact ratio can be secured even in a microscopic region, and it is estimated that a high adhesion force can be obtained.

  Examples of the thermoplastic resin include olefin resins [eg, polyethylene (linear low density polyethylene, low density polyethylene, etc.), ethylene-acrylate ester copolymers (ethylene-ethyl acrylate copolymers, etc.), ethylene -Polyethylene such as methacrylic acid ester copolymer, ethylene- (meth) acrylic acid copolymer, ionomer resin, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-acrylonitrile-acrylic acid copolymer Resin, amorphous polypropylene resin, etc.], vinyl chloride resin (vinyl chloride-vinyl acetate copolymer, etc.), vinylidene chloride resin (vinylidene chloride-vinyl chloride copolymer, vinylidene chloride- (meth) acrylic acid) Ester copolymer, vinylidene chloride-acrylonitrile Copolymer or the like), acrylic resin [for example, (meth) acrylic monomer (for example, (meth) acrylic acid, (meth) acrylic acid ester, etc.)] or a copolymer, these (meth) Copolymers of acrylic monomers and copolymerizable monomers (styrene monomers, vinyl ester monomers such as vinyl acetate, unsaturated dicarboxylic acids or their esters, etc.)], vinyl acetate Resin [polyvinyl acetate or saponified product thereof, vinyl acetate and other copolymerizable monomers (olefinic monomer (ethylene etc.), (meth) acrylic acid ester, unsaturated dicarboxylic acid or ester thereof etc.)) Copolymer or saponified product thereof, polyvinyl acetal resin, etc.], styrene resin [for example, styrene- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid Stealth- (meth) acrylic acid copolymer], polyester resin [aliphatic polyester resin, amorphous polyester resin (eg, amorphous aliphatic or aromatic polyester)], urethane resin (thermoplastic urethane) Resin, isocyanate group-containing polymer, etc.), rubbery polymer (styrene-butadiene copolymer, etc.), imino group-containing polymer (polyalkyleneimine, such as polyethyleneimine), and the like. These thermoplastic resins can be used alone or in combination of two or more.

  Among these thermoplastic resins, aqueous or hydrophilic (water-soluble) from the viewpoint that it has high affinity with the binder resin and dispersant in the conductive paste and can improve the adhesion of the conductive layer (metal nanoparticles) to the substrate. Or water dispersible) resins, for example, aqueous vinyl polymers (for example, vinyl polymers containing units composed of poly (meth) acrylic acid or a salt thereof or vinyl alcohol), aqueous polyester resins ( Polyester resins with sulfonate groups or carboxylate groups introduced into the molecule), aqueous urethane resins (urethane resins with ionic functional groups such as free carboxyl groups or tertiary amino groups introduced into the molecule) Etc.). These aqueous resins can be used alone or in combination of two or more, but preferably contain at least an aqueous polyester-based resin from the viewpoint of improving the adhesion between the metal colloid particles constituting the conductive paste and the binder resin. For example, an aqueous polyester resin alone or a combination of an aqueous polyester resin and an aqueous vinyl polymer can be used.

Examples of the aqueous polyester resin include dicarboxylic acid components (aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid and naphthalenedicarboxylic acid, C _6-12 aliphatic dicarboxylic acids such as adipic acid and sebacic acid), and the like. Diol components (ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, C _2-8 alkanediol such as neopentyl glycol, cyclohexane-1,4-dimethanol, etc. In a polyester resin obtained by reaction with an alicyclic diol or the like, a polyester resin having a hydrophilic group introduced can be used. As a method for introducing a hydrophilic group, for example, a dicarboxylic acid component having a sulfonic acid group or a carboxylic acid group as a dicarboxylic acid component [for example, sulfoisophthalic acid (5-sodium sulfoisophthalic acid, etc.) a method using a valence such as carboxylic acids (such as pyromellitic anhydride)], as the diol component, polyalkylene glycols (e.g., diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, poly C _2-4, such as polytetramethylene glycol Alkylene glycol, etc.), dihydroxycarboxylic acid (dimethylolpropionic acid, etc.), dihydroxyamine (N-methyldiethanolamine, etc.), polyol (trimethylolpropane, pentaerythritol, etc.), etc. The method etc. can be illustrated. The number average molecular weight of the water-based polyester resin is, for example, about 1,000 to 100,000, preferably about 5,000 to 50,000, and more preferably about 10,000 to 30,000. Moreover, the glass transition temperature of water-based polyester-type resin may be about 0-100 degreeC, for example, Preferably it is 10-80 degreeC, More preferably, about 20-60 degreeC may be sufficient.

  Examples of the aqueous vinyl polymer include carboxyl group-containing monomers [(meth) acrylic acid, maleic acid, etc.], hydroxyl group-containing monomers [hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate. , Hydroxybutyl (meth) acrylate, vinyl acetate as a saponified product], amide group-containing monomers [(meth) acrylamide, N-methyl (meth) acrylamide, etc.], sulfonic acid group-containing monomers [vinyl sulfone And vinyl polymers containing a hydrophilic vinyl monomer such as an acid as a polymerization component. Specifically, aqueous acrylic resin [for example, poly (meth) acrylic acid, (meth) acrylic acid ester- (meth) acrylic acid copolymer, (meth) acrylic acid-vinyl acetate copolymer, (meth) Acrylic acid-polyvinyl alcohol copolymer, (meth) acrylic acid-ethylene copolymer, or salts of these (co) polymers], vinyl alcohol polymers (for example, polyvinyl alcohol, ethylene-vinyl alcohol copolymer) And the like, and polyvinyl acetal resins (for example, polyvinyl formal, polyvinyl butyral, etc.).

  The thickness of the adhesive layer can be selected from a range of about 0.01 to 20 μm, and is, for example, 0.05 to 15 μm, preferably 0.1 to 10 μm, and more preferably 0.3 to 5 μm from the viewpoint of improving adhesiveness. It is about (especially 0.5-3 micrometers). In the present invention, the thickness of the adhesive layer is 0.05 to 2 μm in the case where the electrical connection with the substrate is required (for example, when a conductive substrate such as a carbon substrate is used as the substrate). Preferably it may be 0.1-1 micrometer, More preferably, it may be about 0.1-0.5 micrometer (especially 0.05-0.3 micrometer), and while being able to implement | achieve high electroconductivity, adhesiveness is also securable.

[Conductive paste]
The conductive paste of the present invention contains conductive particles, a binder resin, and a dispersion medium.

(1) Conductive particles The conductive particles preferably include conductive metal particles. For example, metal colloid particles having a dispersant, metal filler (powder), and the like can be used. The metal colloid particles (A) and the metal filler (B) can be used alone, but it is preferable to use both in combination.

(A) Metal colloid particles The metal colloid particles are composed of metal nanoparticles (A1) and a dispersant (A2).

(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 dispersant, 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. Among them, the metal constituting the metal nanoparticles (A1) is a metal (metal simple substance and metal alloy) containing at least a noble metal such as silver (especially Group 1B metal of the periodic table), particularly a noble metal simple substance (for example, silver simple substance). Is preferred.

  The metal nanoparticles (A1) are nanometer size. The number average particle diameter (number average primary particle diameter) of the metal nanoparticles (A1) in the metal colloid particles is, for example, 1 to 100 nm, preferably 1.5 to 80 nm, more preferably 2 to 70 nm, and particularly about 3 to 50 nm. It may be about 10 to 40 nm (for example, about 20 to 35 nm).

  In addition, the metal colloid particles may contain almost no coarse particles. Therefore, the maximum primary particle diameter of the metal nanoparticles (A1) is, for example, 200 nm or less, preferably 150 nm or less, and more preferably 100 nm or less. Furthermore, in the metal nanoparticles (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, 0 to 8% by mass) based on the mass of the metal (or metal component). Degree), 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).

(A2) Dispersant The dispersant (A2) may cover the metal nanoparticle surface, and is composed of an agglomeration aid (A2-1) and a polymer dispersant (A2-2).

(A2-1) Aggregation aid (low molecular aggregation aid)
The aggregation aid (A2-1) is a component that acts on the metal nanoparticles and controls the dispersibility of the colloidal particles by the polymer dispersant (A2-2) described later in the solvent, such as a low molecular organic compound. And a component having a physical or chemical affinity for the metal nanoparticle or having a site capable of bonding (chemical bond such as hydrogen bond, ionic bond, and coordinate bond). In particular, in order to moderately promote the aggregation of colloidal particles while suppressing the growth of metal nanoparticles (increase in particle size) in a solvent, a low molecular organic compound having a carboxyl group is preferable.

  The number of such carboxyl groups is not particularly limited as long as it is 1 or more per molecule of the organic compound, and may be, for example, 1 to 10, preferably 1 to 5, and more preferably about 1 to 3.

  In the organic compound, some or all of the carboxyl groups may form a salt (a salt with an amine, a metal salt, or the like). In particular, in the present invention, an organic compound in which a carboxyl group (particularly, all carboxyl groups) does not form a salt [particularly, a salt with a basic compound (a salt with an amine or an amine salt)] The organic compound having a carboxyl group can be preferably used.

Moreover, as long as the organic compound has a carboxyl group, it may have a functional group other than the carboxyl group (or a coordinating group for the metal compound or the metal nanoparticles). The functional group (or coordinating group) other than the carboxyl group is selected from, for example, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), nitrogen atom, oxygen atom, and sulfur atom. A group having at least one heteroatom {or a functional group such as a group having a nitrogen atom [amino group, substituted amino group (dialkylamino group etc.), imino group (—NH—), nitrogen ring group (pyridyl group) 5-8 membered nitrogen ring group, carbazole group, morpholinyl group, etc.), amide group (—CON <), cyano group, nitro group etc.), group having oxygen atom [hydroxyl group, alkoxy group (for example, methoxy group, etc.) , An ethoxy group, a propoxy group, a butoxy group and other C _1-6 alkoxy groups), a formyl group, a carbonyl group (—CO—), an ester group (—COO—), oxygen A cyclic group (such as a 5- to 8-membered oxygen ring group such as a tetrahydropyranyl group)], a group having a sulfur atom [for example, a thio group, a thiol group, a thiocarbonyl group (—SO—), an alkylthio group (a methylthio group, C _1-4 alkylthio group such as ethylthio group, etc.), sulfo group, sulfamoyl group, sulfinyl group (—SO ₂ —) and the like], groups forming these salts (such as ammonium base), etc.}. These functional groups may be contained in the organic compound alone or in combination of two or more.

  Of these functional groups, the organic compound is preferably a compound that does not have a basic group capable of forming a salt with a carboxyl group (in particular, an amino group, a substituted amino group, an imino group, an ammonium base, or the like). .

  Typical aggregation aids include carboxylic acids. Examples of such carboxylic acid include monocarboxylic acid, polycarboxylic acid, and hydroxycarboxylic acid (or oxycarboxylic acid).

Examples of monocarboxylic acids include aliphatic monocarboxylic acids [saturated aliphatic monocarboxylic acids (eg, formic acid, acetic acid, propionic acid, butyric acid, caprylic acid, caproic acid, hexanoic acid, capric acid, lauric acid, myristic acid, C _1-34 aliphatic monocarboxylic acid such as stearic acid, cyclohexanecarboxylic acid, dehydrocholic acid, colanic acid, preferably _C1-30 aliphatic monocarboxylic acid), unsaturated aliphatic monocarboxylic acid (for example, olein) _C4-34 unsaturated aliphatic carboxylic acid such as acid, erucic acid, linoleic acid, and abietic acid, preferably _C10-30 unsaturated aliphatic carboxylic acid)], aromatic monocarboxylic acid (benzoic acid, naphthoic acid, etc.) C _7-12 aromatic monocarboxylic acid, etc.).

Examples of polycarboxylic acids include aliphatic polycarboxylic acids [for example, aliphatic saturated polycarboxylic acids (for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, etc. C _2-14 aliphatic saturated polycarboxylic acid, preferably C _2-10 aliphatic saturated polycarboxylic acid, etc., aliphatic unsaturated polycarboxylic acid (eg maleic acid, fumaric acid, itaconic acid, sorbic acid, tetrahydro C _4-14 aliphatic unsaturated polycarboxylic acid such as phthalic acid, preferably C _4-10 aliphatic unsaturated polycarboxylic acid etc.], aromatic polycarboxylic acid (eg phthalic acid, trimellitic acid etc.) C _8-12 aromatic polycarboxylic acid and the like).

Hydroxycarboxylic acids include hydroxymonocarboxylic acids [aliphatic hydroxymonocarboxylic acids (eg, glycolic acid, lactic acid, oxybutyric acid, glyceric acid, 6-hydroxyhexanoic acid, cholic acid, deoxycholic acid, chenodeoxycholic acid, 12-oxo C _2-50 aliphatic hydroxymonocarboxylic acids, preferably C _2-34 aliphatic hydroxymonocarboxylic acids such as chenodeoxycholic acid, glycocholic acid, lithocholic acid, hyodeoxycholic acid, ursodeoxycholic acid, apocholic acid, taurocholic acid More preferably, C _2-30 aliphatic hydroxy monocarboxylic acid, etc.), aromatic hydroxy monocarboxylic acid (eg, C _7-12 aromatic hydroxy monocarboxylic acid such as salicylic acid, oxybenzoic acid, gallic acid, etc.)], hydroxy Polica Rubonic acid [aliphatic hydroxypolycarboxylic acid (for example, C _2-10 aliphatic hydroxypolycarboxylic acid such as tartronic acid, tartaric acid, citric acid, malic acid and the like)] and the like.

  These carboxylic acids may form a salt, and may be anhydrides, hydrates, and the like. As described above, the carboxylic acid often does not form a salt (in particular, a salt with a basic compound such as a salt with an amine).

These carboxylic acids may be used alone or in combination of two or more. Among these carboxylic acids, C _1-24 saturated aliphatic monocarboxylic acid (eg, acetic acid, propionic acid, stearic acid, etc.), C _4-24 unsaturated aliphatic monocarboxylic acid (eg, linoleic acid, oleic acid, etc.) ), C _10-34 condensed polycyclic aliphatic hydroxycarboxylic acid (eg, cholic acid), C _10-34 condensed polycyclic aliphatic carboxylic acid (eg, dehydrocholic acid, colanic acid, etc.), C _{2− 10} aliphatic hydroxy monocarboxylic acids (eg, glycolic acid, lactic acid, oxybutyric acid, etc.), C _2-10 aliphatic hydroxy polycarboxylic acids (eg, tartaric acid, citric acid, malic acid, etc.), C _2-6 aminocarboxylic acid (e.g., glycine, _{alanine), C 1-4} alkyl _{C 2-6} amino acids (e.g., N, N-dimethylamino acetate, N, N Dimethylamino such acid) and the like are preferable. Furthermore, among these carboxylic acids, hydrophilic or water-soluble carboxylic acids are particularly preferable.

  The molecular weight of the aggregation aid (A2-1) is, for example, 1000 or less (for example, about 46 to 900), preferably 800 or less (for example, about 50 to 500), and more preferably 300 or less (for example, about 55 to 200). ).

  Further, the pKa value of the aggregation aid (A2-1) may be, for example, 1 or more (for example, about 1 to 10), preferably about 2 or more (for example, about 2 to 8).

The aggregation assistant (A2-1) may be not only the same type of compound but also a combination of different types of compounds. However, since the carboxyl group of the carboxylic acid has a high affinity with the metal nanoparticles, at least carboxylic acids are used. It is preferable to include. Carboxylic acids may be used alone or as other agglomeration aids such as amines (for example, C _1-10 alkylamines such as dimethylamine and octylamine, N-methyldiethanolamine and N, N-dimethylethanolamine). C _1-3 alkyl C _2-6 alkanol tertiary amine, etc.), amides (eg, N, N-dimethylformamide, etc.), hydroxy compounds (eg, C _1-4 alkanols such as ethanol, etc.) and the like A combination of these may be used.

  Furthermore, the agglomeration aid (A2-1) is a colloidal particle production process in which the produced colloidal particles agglomerate in a solvent and can form a sintered site by being decomposed at a low temperature in the formation of a sintered film. The number of carbon atoms is preferably 1 to 18, preferably 1 to 10, more preferably about 1 to 6 (particularly 1 to 4). Such an agglomeration aid can be desorbed or disappeared from the metal particles at the firing temperature to improve the continuity and conductivity of the metal film by forming sintered sites.

Specifically, from the point of high affinity with the surface of the metal nanoparticles, excellent cohesiveness and sinterability, carboxylic acids having the above carbon number, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, etc. C _1-10 alkanoic acid (alkanecarboxylic acid) of C _1-6 alkanoic acid such as acetic acid and propionic acid (preferably C _1-4 alkanoic acid, more preferably C _2-3 alkanoic acid, especially acetic acid) Is more preferable. In particular, when a _C1-4 alkanoic acid such as acetic acid is used, the generation of cracks and voids during combustion is suppressed because the metal colloidal particles are appropriately aggregated, and a dense and hard fired film can be formed.

  The boiling point of the aggregation aid (A2-1) is preferably, for example, 200 ° C. or less, for example, 80 to 180 ° C., preferably 90 to 170 ° C., more preferably 100 to 150 ° C. (particularly 110 to 130 ° C.). There may be.

(A2-2) Polymer dispersing agent In this invention, a dispersing agent (A2) is comprised combining with the said aggregation adjuvant (A2-1) and a polymer dispersing agent (A2-2). By configuring the dispersant (A2) in such a combination, metal colloidal particles containing metal nanoparticles with extremely few coarse particles can be obtained. In particular, the combination of the dispersing agent (A2) can increase the proportion of metal nanoparticles, and can stably produce metal colloid particles in the reduction reaction step. Since it aggregates or precipitates by centrifugation, it can be easily removed from the reaction solution. The reason why such an excellent colloidal metal particle is obtained and agglomerated by the combination is not clear, but the following reasons are conceivable.

  First, the polymer dispersant (A2-2) is excellent in the effect of stabilizing the dispersion of relatively large particles due to its structure, but the effect of stabilizing the relatively small particles is not sufficient. When the concentration of the raw material is increased, the generated particles cannot be sufficiently stabilized. On the other hand, the agglomeration aid (B1) stabilizes dispersion of relatively small particles generated in the initial synthesis stage of such nanoparticles. It is considered that metal nanoparticles can be generated even when the concentration of the raw material of the metal nanoparticles is high due to the synergistic action of the aggregation assistant (A2-1) and the polymer dispersant (A2-2). It is done.

  In the present invention, if the proportion of the dispersant (A2) is relatively small, the dispersion stability of the relatively large metal colloid particles produced cannot be maintained, and the binding of the aggregation aid (A2-1). It is considered that the site becomes a weak point, colloidal metal particles are generated, and aggregation starts. In particular, in the present invention, although aggregation of metal colloid particles occurs, the aggregation aid (A2-1) and polymer dispersant (A2-2) combined at a specific ratio appropriately coat the metal nanoparticles. Therefore, the growth of metal nanoparticles is moderately suppressed, and metal particles with a unit of several hundred nm are not generated. Therefore, in this invention, it can be estimated that nanometer-sized metal colloidal particles can be easily taken out as a precipitate by such an action mechanism.

  Furthermore, in the present invention, even if the metal colloid particles are aggregated, the metal particles maintain a nanometer size, and therefore, by firing, a highly conductive, hard and dense sintered film can be formed. In particular, cracking of the fired film and generation of voids can be suppressed because the metal colloidal particles are aggregated before firing and the nanoparticles are close to each other. That is, by the combination, an adsorption part of the polymer dispersant (A2-2) and an adsorption part of the aggregation aid (A2-1) are formed on the surface of the metal nanoparticles. And while the adsorbing part of the polymer dispersant (A2-2) is stabilized by strong surface protection ability, the adsorbing part of the aggregation aid (A2-1) is easily detached from the surface of the metal nanoparticles, It plays a role as a reaction site for low-temperature sintering. Such a reaction site is protected by the action of the polymer dispersant (A2-2) in an atmosphere of about room temperature, but between the nanoparticles at a relatively low firing temperature (for example, about 50 ° C. or more). As a result, it seems that a low resistance metal film can be obtained even by low-temperature firing. In particular, the higher the firing temperature, the higher the interparticle collision and sinterability than the protective ability of the polymer dispersant, so that the conductivity is comparable to that of a bulk metal. In addition, the polymer dispersant not only has an effect of improving the adhesion to the transparent conductive film, but also can reduce the residual amount of the polymer dispersant in the transparent conductive film in the present invention. Therefore, in the present invention, a dense and highly adhesive film with small volume shrinkage can be formed, so that these points are also excellent in adhesion to the substrate and firmly fixed to the substrate, and the conductivity of the metal film is improved. It is a possible factor.

  The polymer dispersant (or polymer type dispersant) (A2-2) is not particularly limited as long as the metal nanoparticles can be coated or interposed between the particles, but the amphiphilic polymer dispersant (or oligomer) Type dispersing agent) can be preferably used.

  Examples of the polymer dispersant include polymer dispersants usually used for dispersing colorants in the paint and ink fields. Such dispersants include styrene resins (styrene- (meth) acrylic acid copolymers, styrene-maleic anhydride copolymers, etc.), acrylic resins ((meth) methyl acrylate- (meth) acrylic acid). Copolymers, (meth) acrylic resins such as poly (meth) acrylic acid), water-soluble urethane resins, water-soluble acrylic urethane resins, water-soluble epoxy resins, water-soluble polyester resins, cellulose derivatives (nitrocellulose; ethyl cellulose Cellulose ethers such as alkylcelluloses such as alkyl-hydroxyalkylcelluloses such as ethylhydroxyethylcellulose, hydroxyalkylcelluloses such as hydroxyethylcellulose, hydroxypropylcellulose, carboxyalkylcelluloses such as carboxymethylcellulose ), Polyvinyl alcohol, polyalkylene glycol (liquid polyethylene glycol, polypropylene glycol, etc.), natural polymers (polysaccharides such as gelatin, dextrin, arabic gum, casein), polyethylene sulfonic acid or salts thereof, polystyrene sulfonic acid or Salt, formalin condensate of naphthalenesulfonic acid, nitrogen atom-containing polymer compound [for example, polyalkyleneimine (polyethyleneimine etc.), polyvinylpyrrolidone, polyallylamine, polyether polyamine (polyoxyethylene polyamine etc.) Polymer compound] and the like.

  As a typical polymer dispersant (amphiphilic polymer dispersant), a resin (or water-soluble resin, water-dispersible resin) containing a hydrophilic unit (or hydrophilic block) composed of a hydrophilic monomer. Is included.

  Examples of the hydrophilic monomer include carboxyl group or acid anhydride group-containing monomers ((meth) acrylic monomers such as acrylic acid and methacrylic acid, unsaturated polycarboxylic acids such as maleic acid, and maleic anhydride. Acid), hydroxyl group-containing monomers (hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, vinylphenol, etc.) and other addition polymerization monomers; condensation monomers such as alkylene oxide (ethylene oxide, etc.) Etc. can be exemplified. The condensed monomer may form a hydrophilic unit by a reaction with an active group such as a hydroxyl group (for example, the hydroxyl group-containing monomer). The hydrophilic monomers may form a hydrophilic unit alone or in combination of two or more.

The polymer dispersant only needs to contain at least a hydrophilic unit (or hydrophilic block), and may be a homopolymer or a copolymer of a hydrophilic monomer (for example, polyacrylic acid or a salt thereof). It may be a copolymer of a hydrophilic monomer and a hydrophobic monomer, such as an exemplary styrene resin or acrylic resin. Examples of hydrophobic monomers (nonionic monomers) include (meth) acrylic acid esters [methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate. , (Meth) acrylic acid lauryl, (meth) acrylic acid C _1-20 alkyl such as stearyl (meth) acrylate, (meth) acrylic acid cycloalkyl such as cyclohexyl, (meth) acrylic acid phenyl, etc. (Meth) acrylic monomers such as aryl (meth) acrylate, benzyl (meth) acrylate, aralkyl (meth) acrylate such as 2-phenylethyl (meth) acrylate, etc .; styrene, α-methylstyrene, styrenic monomers such as vinyl toluene; _{α-C 2-20} olefin (ethylene , Propylene, 1-butene, isobutylene, 1-hexene, 1-octene, 1-dodecene, etc.) olefin monomers such as, vinyl acetate, and the like carboxylic acid vinyl ester monomers such as vinyl butyrate. Hydrophobic monomers may constitute a hydrophobic unit alone or in combination of two or more.

  When the polymeric dispersant is a copolymer (eg, a copolymer of a hydrophilic monomer and a hydrophobic monomer), the copolymer can be a random copolymer, an alternating copolymer, a block copolymer (eg, a hydrophilic block composed of hydrophilic monomers). And a copolymer composed of a hydrophobic block composed of a hydrophobic monomer), a star polymer (or a star block copolymer), a comb copolymer (or a comb graft copolymer), and the like. The structure of the block copolymer is not particularly limited, and may be a diblock structure, a triblock structure (ABA type, BAB type), or the like. In the comb copolymer, the main chain may be composed of the hydrophilic block, the hydrophobic block, or the hydrophilic block and the hydrophobic block.

  As described above, the hydrophilic unit may be composed of a condensation block such as a hydrophilic block (polyalkylene oxide such as polyethylene oxide or polyethylene oxide-polypropylene oxide) composed of alkylene oxide (such as ethylene oxide). it can. The hydrophilic block (such as polyalkylene oxide) and the hydrophobic block (such as polyolefin block) may be bonded via a linking group such as an ester bond, an amide bond, an ether bond, or a urethane bond. For example, the hydrophobic block (polyolefin, etc.) is modified with a modifying agent [unsaturated carboxylic acid or its anhydride ((anhydrous) maleic acid), lactam or aminocarboxylic acid, hydroxylamine, diamine, etc.]. Later, it may be formed by introducing a hydrophilic block. In addition, a polymer obtained from a monomer having a hydrophilic group such as a hydroxyl group or a carboxyl group (such as the hydroxyalkyl (meth) acrylate) is reacted (or bonded) with the condensed hydrophilic monomer (such as ethylene oxide). By doing so, a comb-type copolymer (comb-type copolymer having a main chain composed of a hydrophobic block) may be formed.

  Furthermore, the balance between hydrophilicity and hydrophobicity may be adjusted by using a hydrophilic nonionic monomer as a copolymerization component. Examples of such components include monomers having alkyleneoxy (particularly ethyleneoxy) units such as 2- (2-methoxyethoxy) ethyl (meth) acrylate and polyethylene glycol monomethacrylate (for example, a number average molecular weight of about 200 to 1,000). An oligomer etc. can be illustrated. Further, the balance between hydrophilicity and hydrophobicity may be adjusted by modifying (for example, esterifying) a hydrophilic group (such as a carboxyl group).

  The polymer dispersant (A2-2) may have a functional group. Examples of such functional groups include acid groups (or acidic groups such as carboxyl groups (or acid anhydride groups) and sulfo groups (sulfonic acid groups)), basic groups (such as amino groups), A hydroxyl group etc. are mentioned. These functional groups may be contained in the polymer dispersant alone or in combination of two or more.

  Among these functional groups, the polymer dispersant (A2-2) preferably has an acid group or a basic group, particularly a carboxyl group.

  When the polymer dispersant (A2-2) has an acid group (such as a carboxyl group), at least a part or all of the acid group (such as a carboxyl group) is a salt (a salt with an amine, a metal In particular, in the present invention, an acid group such as a carboxyl group (especially all carboxyl groups) is a salt [especially a salt with a basic compound (a salt with an amine or a salt). A polymeric dispersant that does not form an amine salt or the like] [that is, a polymeric dispersant having a free acid group (particularly a carboxyl group)] can be suitably used.

  In the polymer dispersant (A2-2) having an acid group (particularly a carboxyl group), the acid value has no lower limit as long as the surface of the nanoparticle generated when the nanoparticle is produced can be protected, but the lower one Is preferred. If the acid value is too high, a large number of functional groups derived from the polymer are adsorbed or present on the surface of the nanoparticle, so that the number of sintering points decreases, and there is a possibility of inhibiting the sintering between the nanoparticles. For example, it can be selected from a range of 1 mgKOH / g or more (for example, about 2 to 1500 mgKOH / g), particularly 10 mgKOH / g or more (for example, about 12 to 900 mgKOH / g). In particular, when the polymer dispersant having an acid group (particularly a carboxyl group) is a compound having a hydrophilic unit and a hydrophobic unit, the acid value is, for example, 1 mgKOH / g or more (for example, 2 to 100 mgKOH / g). Degree), preferably 3 mgKOH / g or more (for example, about 4 to 90 mgKOH / g), more preferably 5 mgKOH / g or more (for example, about 6 to 80 mgKOH / g), particularly 7 mgKOH / g or more (for example, 8 to 70 mgKOH / g). g), or about 3 to 50 mg KOH / g (for example, 5 to 30 mg KOH / g). In the polymer dispersant having an acid group, the amine value may be 0 (or almost 0).

  In the polymer dispersant, the position of the functional group as described above is not particularly limited, and may be a main chain, a side chain, or a main chain and a side chain. Good. Such a functional group may be, for example, a hydrophilic monomer or a functional group derived from a hydrophilic unit (for example, a hydroxyl group), or a copolymerizable monomer having a functional group (for example, maleic anhydride). It can also be introduced into the polymer by copolymerization.

  The polymer dispersant may be used alone or in combination of two or more.

  As the polymer dispersant, a polymer dispersant (high molecular weight pigment dispersant) described in JP-A No. 11-80647 may be used.

  The polymer dispersant may be a synthesized one or a commercially available product. Specific examples of commercially available polymer dispersants (or dispersants composed of at least an amphiphilic dispersant) include Solsperse 13240, Solsperse 13940, Solsperse 32550, Solsperse 31845, Solsperse 24000, Solsperse 26000, Solsperse series such as Solsperse 27000, Solsperse 28000, Solsperse 41090, etc. [manufactured by Avicia Co., Ltd.]; Big 180, Dispersic 182, Dispersic 184, Dispersic 190, Dispersic 191, Dispersic 92, Dispersic 193, Dispersic 194, Dispersic 2001, Dispersic 2010, Dispersic 2050, Dispersic 2090, Dispersic 2091, etc. Dispersic series [manufactured by BYK Chemie Corp.]; EFKA-46, EFKA-47, EFKA-48, EFKA-49, EFKA-1501, EFKA-1502, EFKA-4540, EFKA-4550, polymer 100, polymer 120, polymer 150, polymer 400, polymer 401, polymer 402, polymer 403, polymer 450, polymer 451 , Polymer 452, polymer 453 [manufactured by EFKA Chemical Co., Ltd.]; Ajisper PB711, Azisper PAl11, Azisper PB811, Ajisper P 821, Ajisper series such as Ajisper PW911 [manufactured by Ajinomoto Co., Inc.]; Floren DOPA-158, Floren DOPA-22, Floren DOPA-17, Floren TG-700, Floren TG-720W, Floren-730W, Floren-740W, Florene series such as Floren-745W [manufactured by Kyoeisha Chemical Co., Ltd.]; John Kuryl series such as John Kuril 678, John Kuryl 679, and John Kuryl 62 [Johnson Polymer Co., Ltd.].

  Among these, polymer dispersants having typical acid groups include poly (meth) acrylic acids [or polyacrylic resins such as poly (meth) acrylic acid and (meth) acrylic acid. Polymers mainly composed of (meth) acrylic acid, such as copolymers with monomers (for example, (meth) acrylate, maleic anhydride, etc.), and salts thereof (for example, alkali metal salts such as sodium polyacrylate) Etc.), Dispersic 190, Dispersic 194 and the like. Examples of the polymer dispersant having a typical basic group (amino group) include polyalkyleneimine (polyethyleneimine etc.), polyvinylpyrrolidone, polyallylamine, polyether polyamine (polyoxyethylene polyamine etc.) and the like. .

  The number average molecular weight of the polymer dispersant (A2-2) is, for example, 1000 to 1000000 (for example, 1200 to 900000), 1500 to 800000, preferably 2000 to 700000, and more preferably 3000 to 500000 (for example, 5000 to 300000). ), Especially about 7000-200000.

  In the metal colloidal particles, the ratio of the dispersant (A2) [the total amount of the coagulation aid (A2-1) and the polymer dispersant (A2-2)] is 100 parts by mass of the metal nanoparticles (A1) in terms of solid content. From the point which can be selected from the range of about 0.1-15 mass parts, and is excellent in the balance of operativity and the electroconductivity of a sintered film, for example, 0.5-12 mass parts (for example, 0.5-10 mass parts). Part by mass), preferably 1 to 10 parts by mass (for example, 2 to 10 parts by mass), more preferably about 3 to 8 parts by mass (particularly 4 to 6 parts by mass). Furthermore, the ratio of the dispersing agent (B) is, for example, 0.5 to 5 parts by mass with respect to 100 parts by mass of the metal nanoparticles (A) from the viewpoint of obtaining a highly dense and highly conductive fired film. Preferably it may be about 1 to 4 parts by mass, more preferably about 1.5 to 3 parts by mass.

  The ratio of the coagulation aid (A2-1) and the polymer dispersant (A2-2) (the ratio of the solid content when a solvent or the like is included) is, for example, the former / the latter (mass ratio) = 99/1 to 1. For example, 90/10 to 1/99, preferably 80/20 to 3/97 (for example, 70/30 to 5/95), and more preferably 50/50 to 10/90. (Especially 40/60 to 15/85) may be sufficient. Furthermore, the former / the latter (mass ratio) = 90/10 to 10/90, preferably 70/30 to the point that a sintered film of colloid is enlarged to obtain a highly dense and highly conductive fired film. It may be about 20/80, more preferably about 60/40 to 30/70. In order to increase the proportion of the aggregation assistant (A2-1), it is effective to add an aggregation assistant (particularly an alkanecarboxylic acid) in addition to the reducing agent.

  In the present invention, by setting the ratio of the dispersing agent (A2) in such a range, as described above, colloidal particles containing metal nanoparticles can be obtained as aggregates.

  The proportion of the coagulation aid (A2-1), the polymer dispersant (A2-2), etc. in the metal colloidal particles is a conventional method, for example, thermal analysis (for example, thermal mass / differential thermal simultaneous analysis, etc.). Can be measured.

(A) Method for producing metal colloidal particles Metal colloidal particles (A) can be obtained by a conventional method, for example, reduction of a metal compound corresponding to the metal nanoparticles in a solvent in the presence of a dispersant (A2) and a reducing agent. Can be prepared.

  Examples of metal compounds corresponding to the metal nanoparticles include metal oxides, metal hydroxides, metal sulfides, metal halides, metal acid salts [metal inorganic acid salts (sulfates, nitrates, perchlorates, etc. Oxo acid salts, etc.), metal organic acid salts (acetates, etc.), etc.]. 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). Salts), boranes (diborane, dimethylamine borane, etc.), hydrazine, formalin, amines, alcohols (the alcohols exemplified above, such as ethylene glycol), carboxylic acids having a phenolic hydroxyl group (eg, tannic acid) And the like.

Examples of amines include aliphatic amines (for example, propylamine, butylamine, hexylamine, diethylamine, dipropylamine, dimethylethylamine, diethylmethylamine, triethylamine, ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine). 1,3-diaminopropane, alkaneamines such as N, N, N ′, N′-tetramethyl-1,3-diaminopropane; polyalkylene polyamines such as triethylenetetramine and tetraethylenepentamine), and alicyclic rings Formula amines (eg piperidine, N-methylpiperidine, piperazine, N, N′-dimethylpiperazine, pyrrolidine, N-methylpyrrolidine, morpholine, etc.), aromatic amines (eg aniline, N-methylaniline, N, N-dimethyl Nilin, toluidine, anisidine, phenetidine, etc.), araliphatic amines (for example, benzylamine, N-methylbenzylamine, N, N-dimethylbenzylamine, phenethylamine, xylylenediamine, N, N, N ′, N ′ Aralkylamines such as tetramethylxylylenediamine), alcohol amines [especially alkanolamines such as methylaminoethanol, dimethylaminoethanol (2- (dimethylamino) ethanol), ethanolamine, diethanolamine, triethanolamine, methyl diethanolamine, propanolamine, 2- (3-aminopropyl amino) ethanol, butanol amine, hexanol amine, _{C 2-10} alkanol amines such as dimethylamino propanol, preferably May be mentioned is _{C 2-6} alkanolamine.

  Among these, sodium borohydride, tertiary amine (for example, tertiary alkanolamine such as 2- (dimethylamino) ethanol and N-methyldiethanolamine), ethylene glycol, tannic acid and the like can be preferably used. In view of safety, amines, particularly alcohol amines such as alkanolamines are preferred. Alkanolamines are usually water-soluble in many cases, and are suitable when water or an aqueous solvent is used as a solvent.

  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). Moreover, you may perform reaction under stirring (or stirring) normally.

  In addition, the solvent (for example, water etc.) similar to the above can be used for the reaction solvent. As the reaction solvent, a dispersion medium constituting the conductive paste described later may be used, or a solvent different from the dispersion medium constituting the conductive paste may be used. Specifically, the reaction solvent can be selected from a polar solvent and a hydrophobic solvent depending on the type of the dispersant (A2). Usually, when the dispersant is a water-soluble compound, the reaction solvent is polar such as water. Often a solvent is used. The polar solvent may be derived from a component added to the reaction system, for example, a solvent such as a reducing agent. On the other hand, when the dispersant is a water-insoluble compound, a hydrophobic solvent such as an aliphatic hydrocarbon (such as trimethylpentane) is often used, and if necessary, a hydrophobic solvent and a polar solvent (for example, ethanol, Alcohols such as isopropanol, ketones such as acetone, cyclic ethers such as dioxane and tetrahydrofuran, and amides such as dimethylacetamide) may be used. In addition, the density | concentration of the said metal compound in a reaction solvent is the density | concentration similar to the density | concentration of the metal nanoparticle in the said dispersion liquid in conversion of the mass of a metal, for example, 5 mass% or more (for example, 6-50 mass%), The high concentration is preferably 8% by mass or more (for example, 9 to 40% by mass), more preferably 10% by mass or more (for example, 12 to 30% by mass), and usually about 5 to 30% by mass. In the present invention, even when the reaction is performed at such a high concentration, metal nanoparticles can be obtained efficiently while suppressing the generation of coarse particles.

  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 or phosphoric acid, an organic acid such as acetic acid), an alkali [an inorganic base such as sodium hydroxide or ammonia, or an amine (for example, an alkyl). Bases such as organic bases such as tertiary amines such as amines and alkanolamines].

  After completion of the reduction reaction, the reaction mixture is concentrated and purified by conventional methods (for example, centrifugation, membrane filter, ultrafiltration, etc.), so that the metal colloid has dispersibility in the solvent. Particles can be prepared. In the present invention, since the dispersant is constituted by the specific combination, as described above, even with a relatively small amount of the dispersant, metal nanoparticles with few coarse particles can be obtained and purified. Without it, metal colloidal particles can be prepared. Further, the obtained dispersion containing the metal colloid particles and the solvent may be blended into the conductive paste as it is, and the solvent used in the reaction is removed from the dispersion containing the obtained metal colloid particles and the solvent to obtain a new one. A different type of solvent (other additives as required) may be added to prepare a new dispersion.

(B) Metal filler (powder)
In the present invention, by combining the metal colloid particles (A) with the metal filler (B), the paste can be given fluidity and the conductivity of the sintered film can be improved.

  In the paste containing the metal colloidal particles (A), as the particle concentration in the paste increases, the distance between the particles decreases, interaction due to entanglement of the dispersing agent existing between the particles or on the surface occurs, and the viscosity rapidly increases. As a result, the handleability decreases. In this invention, high fluidity | liquidity can be provided even if it is a high concentration paste by adding the metal filler (B) of a large particle size. In addition, the following reasons can be considered as a mechanism in which fluidity develops.

  (I) The distance D between the surfaces of the particles is expressed by the formula: D = [{(√2π) / (6f)} 1 / 3-1] × d (where, f: volume fraction of fine particles in the paste, d: particle diameter), when compared with pastes having the same metal concentration, it is estimated that the dispersion containing the component having a larger particle diameter has a larger distance between the particle surfaces, so that the viscosity is lowered.

  (Ii) The sedimentation rate D of particles is expressed by the formula: D = kT / (3πηd) (wherein, k: Boltzmann constant, T: absolute temperature, η: solvent viscosity, d: particle size), and the same metal Since large particles have a large sedimentation speed in a paste having a concentration, if large particles are present in the dispersion, it is presumed that the aggregated structure is easily broken and fluidity is developed.

  Furthermore, in the present invention, by adding the metal filler (B) having a larger particle diameter to the paste containing the metal colloidal particles (A), the proportion of the dispersant contained in the paste is reduced, and the dispersion generated during firing is reduced. The amount of gas derived from the agent is reduced, and the occurrence of blistering and cracking due to outgassing from the film can be suppressed. Furthermore, a coating film having high conductivity can be obtained even if firing is performed at a low temperature (for example, 150 ° C. or less) because the filling efficiency is improved by the combination of the nanoparticles and the metal filler.

  The number average particle diameter of such a metal filler (B) may be 200 nm or more, for example, 0.2 to 10 μm, preferably 0.3 to 8 μm (for example, 0.5 to 7 μm), more preferably. It is about 0.7-6 micrometers (especially 1-5 micrometers). The particle size range of the metal filler (B) is, for example, 0.1 to 30 μm, preferably 0.2 to 20 μm (for example, 0.25 to 10 μm), more preferably 0.3 to 8 μm (particularly 0.5 to About 7 μm). If the particle diameter of the metal filler is too large, clogging is likely to occur in screen printing, for example. On the other hand, when the particle diameter is too small, the dispersibility of the metal filler is lowered, so that the amount of the dispersant used is increased, and the amount of gas generated during firing is also increased.

  The ratio of the average particle diameter of the metal colloid particles (A) and the metal filler (B) is as follows: metal colloid particles (A) / metal filler (B) = 1/1000 to 1/5, preferably 1/500 to 1 / 10 (for example, 1/300 to 1/20), more preferably 1/200 to 1/30 (particularly 1/100 to 1/40). When the ratio between the two is in this range, the filling efficiency of the metal colloid particles and the metal filler is improved, so that the conductivity of the fired film can be improved.

  Examples of the metal constituting the metal filler (B) include simple metals, alloys, and metal compounds exemplified in the section of metal nanoparticles (A1). Among these metals, a metal (a simple metal and a metal alloy) including at least a noble metal such as silver or gold (particularly a Group 1B metal of the periodic table), particularly a simple noble metal (for example, a simple gold) is preferable. The metal constituting the metal nanoparticles and the metal constituting the metal filler may be different, but are preferably the same or the same group metals (particularly the same metal) from the viewpoint of easy sintering.

  The ratio (mass ratio) between the metal colloid particles (A) and the metal filler (B) is as follows: metal colloid particles (A) / metal filler (B) = 90/10 to 10/90, preferably 80/20 to 20 / 80, more preferably about 70/30 to 30/70 (particularly 60/40 to 40/60). If the ratio between the two is in this range, the sintering of the two is densely performed, so that the conductivity of the fired film can be improved.

(2) Binder resin As the binder resin, any conductive binder resin can be used as long as the conductive particles can be fixed to the base material. However, since it is necessary to develop an adhesive action by heating in the firing step, hot melt resin or heat A curable resin is preferred. Examples of the hot melt resin that can be used include polyamide resins, polyester resins, styrene resins, olefin resins, polyvinyl acetate resins, acrylic resins, vinyl chloride resins, and thermoplastic urethane resins. On the other hand, as the thermosetting resin, for example, resol type or novolac type phenol resin, polyurethane resin, urea resin, melamine resin, furan resin, epoxy resin, vinyl ester resin, unsaturated polyester resin, diallyl phthalate Resins, thermosetting acrylic resins, polyimide resins, silicone resins and the like can be used. Furthermore, the thermosetting resin may be used in combination with a conventional curing agent.

  Among these binder resins, from the viewpoint of adhesiveness, the hot melt resin is preferably a polyester resin such as aliphatic or amorphous polyester, or a polyvinyl acetal resin such as polyvinyl butyral, and the thermosetting resin is phenol. Of these, epoxy resins, epoxy resins and unsaturated polyester resins are preferred. Furthermore, in the present invention, thermosetting resins (for example, epoxy group-containing thermosetting resins such as epoxy (meth) acrylates and epoxy resins) can be used to adhere the conductive particles to the base material even at a low temperature and in a small amount. Etc.) is preferable, and an epoxy resin is particularly preferable from the viewpoint of excellent adhesion and heat resistance.

  Examples of the epoxy resin include conventional epoxy resins such as a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, an alicyclic epoxy resin, and a glycidyl amine type epoxy resin.

Examples of glycidyl ether type epoxy resins include bisphenol type epoxy resins [for example, epoxy resins having a bis (hydroxyphenyl) C _1-10 alkane skeleton such as bisphenol A type, bisphenol F type, and bisphenol AD type epoxy resins, and bisphenol S type epoxy. Resin etc.], novolac type epoxy resin (eg phenol novolak type, cresol novolak type epoxy resin etc.), aliphatic type epoxy resin (eg hydrogenated bisphenol A type epoxy resin, propylene glycol mono to diglycidyl ether, pentaerythritol mono To tetraglycidyl ether), monocyclic epoxy resin (for example, resorcing ricidyl ether), heterocyclic epoxy resin (for example, triglycid having a triazine ring) Examples thereof include diisocyanurate, hydantoin-type epoxy resin having a hydantoin ring, and tetrakis (glycidyloxyphenyl) ethane.

  Examples of the glycidyl ester type epoxy resin include glycidyl esters of carboxylic acids (particularly polyvalent carboxylic acids) such as diglycidyl phthalate, diglycidyl terephthalate, dimethyl glycidyl phthalate, diglycidyl tetrahydrophthalate, and diglycidyl hexahydrophthalate.

  Examples of the alicyclic epoxy resin include alicyclic diepoxy acetal, alicyclic diepoxy adipate, alicyclic diepoxycarboxylate, vinylcyclopentadiene dioxide, vinylcyclohexene mono-dioxide, and the like.

  Examples of the glycidylamine type epoxy resin include reaction products of amines (particularly polyamines) and epichlorohydrin, such as tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, diglycidylaniline, diglycidyltoluidine, and the like.

  These epoxy resins can be used alone or in combination of two or more. Among these epoxy resins, a bisphenol type epoxy resin having a bisphenol A skeleton is preferable from the viewpoint of heat resistance, adhesiveness, and the like.

  The molecular weight of the epoxy resin is 70 to 10000, preferably 100 to 5000, and more preferably about 200 to 1000 in terms of number average molecular weight. The epoxy equivalent is 50 to 5000 g / eq, preferably 100 to 3000 g / eq, and more preferably 150 to 2000 g / eq (particularly 150 to 1500 g / eq).

  Examples of the curing agent include amine-based curing agents [for example, aliphatic polyamines (ethylenediamine, diethylenetriamine, triethylenediamine, tetraethylenepentamine, diethylaminopropylamine, hexamethylenediamine, etc.), alicyclic polyamines (mensendiamine, isophorone). Diamine, etc.), aromatic polyamines (xylene diamine, metaphenylene diamine, etc.)], polyaminoamide-based curing agents (for example, polycondensates of polyethylene polyamine and fatty acids), acid and acid anhydride-based curing agents [for example, fat Aromatic carboxylic acid anhydrides (dodecenyl succinic anhydride, polyadipic acid anhydride, etc.), alicyclic carboxylic acid anhydrides (methyltetrahydrophthalic anhydride, methyl hymitic anhydride), aromatic carboxylic acid anhydrides (phthalic anhydride, Anhydrous trime Etc. preparative acid), etc.], and others. These curing agents can be used alone or in combination of two or more. Of these curing agents, amine-based curing agents such as the amine-based curing agents or modified products thereof (epoxy adducts, Mannich reaction products, Michael reaction products, thiourea reaction products, etc.) are preferred.

  The ratio of a hardening | curing agent is 1-30 mass parts with respect to 100 mass parts of epoxy resins, Preferably it is 2-20 mass parts, More preferably, it is a 3-15 mass part (especially 5-10 mass part) grade. .

  The ratio of the binder resin can be used at a ratio of about 10 parts by mass or less with respect to 100 parts by mass of the conductive particles (when the conductive particles are composed of metal colloid particles and a metal filler, the total of both), A small amount is preferable from the viewpoint of improving conductivity, for example, 0.1 to 5 parts by mass, preferably 0.2 to 4 parts by mass, more preferably 0.3 to 3 parts by mass (particularly 0.5 (About 2 parts by mass). In particular, when the substrate is composed of an organic material, the ratio of the binder resin is, for example, 0.1 to 2 parts by mass, preferably 0.5 to 2 parts by mass, with respect to 100 parts by mass of the conductive particles. More preferably, it may be about 0.7 to 1.5 parts by mass. In the present invention, since the adhesive layer is formed, even when the amount of the binder resin is small, the conductive particles can be firmly attached to the substrate, so that high conductivity can be realized.

  In the present invention, since the adhesive layer is formed, the conductive paste itself does not require a high adhesive force, so that the ratio of the binder resin in the conductive paste can be reduced and a low resistivity can be realized. Further, when an adhesive layer is formed on the substrate and the conductive paste contains metal colloid particles, a certain amount of adhesion can be obtained even if the conductive paste does not contain a binder resin, but a small amount of binder. It is estimated that by adding the resin, the voids in the fired film will be reduced moderately and the contact efficiency with the adhesive layer will improve, or the adhesive force will improve due to the synergistic effect of the adhesive layer, metal colloid particles and binder resin it can.

(3) Dispersion medium The dispersion medium is not particularly limited as long as it is a solvent that generates a sufficient viscosity in the paste by combining the conductive particles and the binder resin, and a general-purpose solvent can be used. Examples of the dispersion medium (dispersion solvent) include water, alcohols {eg, aliphatic alcohols [eg, methanol, ethanol, propanol, isopropanol, butanol, hexanol, heptanol, octanol (1-octanol, 2-octanol, etc.)]. , Decanol (such as 1-decanol), lauryl alcohol, tetradecyl alcohol, cetyl alcohol, 2-ethyl-1-hexanol, octadecyl alcohol, hexadecenol, oleyl alcohol and the like saturated or unsaturated C _1-30 aliphatic alcohol, preferably such as saturated or unsaturated C _8-24 aliphatic alcohols, alicyclic alcohols [e.g., cycloalkanols such as cyclohexanol; terpineol, terpene Al such dihydro terpineol Such as monoterpene alcohols], araliphatic alcohols (eg benzyl alcohol, phenethyl alcohol, etc.), polyhydric alcohols (ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, etc.) Glycols such as (poly) C _2-4 alkylene glycol; polyhydric alcohols having three or more hydroxyl groups such as glycerin, 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, trie (Poly) alkylene glycol monoalkyl ethers such as lenglycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol butyl ether; (poly) alkylene glycol monoaryl ethers such as 2-phenoxyethanol), glycol esters (For example, (poly) alkylene glycol acetate such as carbitol acetate), glycol ether esters (for example, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol) Monomethyl ether (Poly) alkylene glycol monoalkyl ether acetates such as acetate), hydrocarbons [eg, aliphatic hydrocarbons (eg, hexane, trimethylpentane, octane, decane, dodecane, tetradecane, octadecane, heptamethylnonane, tetramethylpentadecane) Saturated or unsaturated aliphatic hydrocarbons), alicyclic hydrocarbons (such as cyclohexane), halogenated hydrocarbons (such as methylene chloride, chloroform, dichloroethane), aromatic hydrocarbons (eg, toluene, xylene) Etc.], esters (for example, methyl acetate, ethyl acetate, benzyl acetate, isoborneol acetate, methyl benzoate, ethyl benzoate, etc.), amides (formamide, acylamides such as acetamide, N-methylformamide, N Methylacetamide, N, N-dimethylformamide, N, N- dimethylacetamide mono- or _{di-C 1-4} acyl amides such like), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone), ethers (diethyl ether, di Propyl ether, dioxane, tetrahydrofuran, etc.) and organic carboxylic acids (acetic acid, etc.). These solvents may be used alone or in combination of two or more.

As the solvent, the polar solvent and the hydrophobic solvent described as the reaction solvent can be used according to the type of the dispersant (A2) constituting the metal colloidal particles (A). To prepare a homogeneous paste It is preferable to use a solvent having an affinity for the dispersant (A2). For example, when the dispersant (A2) is hydrophilic, at least a solvent having a polar group (particularly a non-aromatic solvent) is used. It is preferable to configure. Such solvents include aliphatic alcohols (e.g., saturated or unsaturated _C6-30 aliphatic alcohols such as ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, 2-ethyl-1-hexanol, octanol, decanol, etc.) ), Cellosolves (C _1-4 alkyl cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve), cellosolve acetates (C _1-4 alkyl cellosolve acetates such as ethyl cellosolve acetate), carbitols (methylcarbitol) C _1-4 alkyl carbitols such as ethyl carbitol, propyl carbitol and butyl carbitol), aliphatic polyhydric alcohols (for example, ethylene glycol, diethylene glycol, propylene, etc.) Lenglycol, dipropylene glycol, 1,4-butanediol, glycerin, etc.), alicyclic alcohols [for example, cycloalkanols such as cyclohexanol; terpene alcohols such as terpineol, dihydroterpineol (eg, monoterpene alcohol, etc.) ) Etc.] are widely used. The polarity parameter (polarity parameter by Snyder) of such a solvent may be, for example, 2.8 to 11, preferably 3 to 10.5, and more preferably about 3.1 to 10.2.

Among these solvents, saturated or unsaturated C _6-20 aliphatic alcohols such as octanol, aliphatic polyhydric alcohols such as ethylene glycol, and alicyclics such as terpineol, because of their excellent affinity for the dispersant (A2). Alcohol is particularly preferred.

  Moreover, although the boiling point of a dispersion medium (in the case of a mixed solvent, the boiling point of each solvent) changes according to the use of an electrically conductive paste, it is preferable that it is 100 degreeC or more (for example, about 100-300 degreeC), for example, 100 to 400 ° C. (for example, 120 to 380 ° C.), preferably 130 to 370 ° C. (for example, 150 to 350 ° C.), more preferably about 170 to 320 ° C. (for example, 180 to 300 ° C.). Usually, about 180-270 degreeC (for example, 185-250 degreeC) may be sufficient.

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

  In such a paste, the conductive particles present at a high concentration have a high dispersibility in the solvent, and maintain such a high dispersion stability for a long period of time. And by combining such a paste and an adhesive layer, a metal film (conductive layer or conductive pattern) can be reliably formed with high adhesion to the substrate. Furthermore, since the paste is excellent in long-term stability (storage stability) without causing sedimentation, even if a metal film (sintered film) is formed after long-term storage, the resistance value increases in the metal film. And excellent conductivity can be maintained.

  Depending on the application, the paste contains conventional additives such as colorants (dyeing pigments, etc.), hue improvers, dye fixing agents, gloss imparting agents, metal corrosion inhibitors, stabilizers (antioxidants, UV absorbers). Agents), surfactants or dispersants (anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc.), dispersion stabilizers, thickeners or viscosity modifiers, moisturizing agents Agents, thixotropic agents, leveling 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 conductive paste is not particularly limited as long as the paste having the above configuration can be obtained, but it can be usually obtained by dispersing the conductive particles and the binder resin in the dispersion medium.

[Laminate (conductive substrate precursor) and method for producing conductive substrate]
The laminate of the present invention can be produced by forming an adhesive layer on the substrate and then forming a coating film on the adhesive layer using a conductive paste.

  The method for forming the adhesive layer is not particularly limited, and for example, a coating method, a laminating method (extrusion laminating method, dry laminating method), an extrusion molding method, a casting method, or the like can be used. Among these methods, a method of coating a solution obtained by dissolving or dispersing a thermoplastic resin constituting the adhesive layer in a solvent is preferable from the standpoint of simplicity.

  The solvent used for the dope for forming the adhesive layer can be selected according to the type of thermoplastic resin. For example, when the thermoplastic resin is a hydrophilic (aqueous) polyester resin, the hydrophilic polyester resin is dissolved. Alternatively, a dispersible polar solvent can be used. As a polar solvent, the polar solvent illustrated by the dispersion medium of the said electrically conductive paste other than water is mentioned, for example. These polar solvents can be used alone or in combination of two or more. For example, water alone, alcohols alone (for example, aliphatic alcohols such as ethanol and octanol alone, alicyclic alcohols such as terpineol alone), water and A mixed solvent with alcohols (for example, a mixed solvent of water and aliphatic alcohols) may be used. The density | concentration of the thermoplastic resin in dope can be selected from the range of about 0.1-50 mass%, for example according to the thickness of an adhesion layer, Preferably it is 0.5-40 mass%, More preferably, it is 1-30. It is about mass% (especially 2-20 mass%).

  Examples of the coating method include, for example, a flow coating method, a spin coating method, a spray coating method, a screen printing method, a flexographic printing method, a casting method, a bar coating method, a curtain coating method, a roll coating method, a gravure coating method, and a dipping method. , Slit method, photolithography method, ink jet method and the like. The adhesive layer may be formed on the entire surface of the base material in a pattern or the like, but is formed on the entire surface from the viewpoint of improving the adhesion with the conductive layer obtained by baking the conductive paste. Is preferred.

  After application, it may be naturally dried, but may be dried by heating. The heating temperature can be selected according to the type of solvent, and is, for example, about 50 to 200 ° C, preferably about 80 to 180 ° C, and more preferably about 100 to 150 ° C (particularly about 110 to 140 ° C). The heating time is, for example, about 1 minute to 3 hours, preferably about 5 minutes to 2 hours, and more preferably about 10 minutes to 1 hour.

  A method of forming a coating film using a conductive paste can be selected according to the type of the substrate, but can be coated on the adhesive layer using the above-described coating method. Among the coating methods, a pattern may be formed (drawn) with a coating film, and a sintered pattern (sintered film, metal film, sintered body layer, conductor is formed by firing the formed pattern (drawn pattern). Layer). 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.

  The obtained laminate is a precursor of a conductive substrate, and is subjected to a firing step in which the coating film is heated (or baked or heat-treated) at a predetermined temperature. In addition, you may perform a drying process as needed prior to heat processing.

  In the present invention, even at a relatively low temperature, the binder resin exhibits a curing or adhesive action, and the metal nanoparticles are fused to form a continuous film. Even a substrate composed of can be fired. The heat treatment temperature is, for example, about 330 ° C. or less (for example, about 100 to 330 ° C.), preferably about 120 to 320 ° C., and more preferably about 150 to 300 ° C. (particularly about 180 to 250 ° C.). In particular, when the substrate is composed of an organic material, it may be, for example, 250 ° C. or lower (for example, 100 to 250 ° C.), preferably 120 to 220 ° C., and more preferably about 150 to 200 ° C. The heat treatment time (heating time) may be, for example, 10 minutes to 5 hours, preferably 15 minutes to 3 hours, and more preferably about 20 minutes to 1 hour, depending on the heat treatment temperature and the like.

  The thickness of the obtained fired film or metal film (coating after sintering, sintered pattern) can be appropriately selected from the range of about 0.01 to 10000 μm depending on the application, for example, 0.01 to 100 μm, preferably May be about 0.1 to 50 μm, more preferably about 0.3 to 30 μm (particularly 0.5 to 10 μm). In the present invention, a relatively thick film, for example, 0.3 μm or more (for example, 0.3 to 100 μm), preferably 0.5 μm or more (for example, 0.5 to 50 μm), more preferably 1 μm or more (for example, 1 A metal film having a thickness of about 30 μm may be formed. Even if it is such a thick film, it can be set as a highly electroconductive metal film, without impairing the adhesiveness with respect to a base material.

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

(Synthesis example of colloidal silver particles)
66.8 g of silver nitrate, 10 g of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 118 ° C., carbon number 2) as an agglomeration aid (A2-1), and a carboxyl group as a polymer dispersant (A2-2) Molecular dispersant (manufactured by Big Chemie, “Disperbic 190”, amphiphilic dispersant having a polyethylene oxide chain as a hydrophilic unit and an alkyl group as a hydrophobic unit, solvent: water, non-volatile component 40%, acid value 10 mgKOH / G, amine value 0) 2 g was added to 1000 g of ion-exchanged water and stirred vigorously. To this was added 100 g of 2-dimethylaminoethanol (manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was heated and stirred at 70 ° C. for 2 hours. This reaction product was centrifuged at 7000 rpm for 1 hour using a high-speed centrifuge (manufactured by Kokusan Co., Ltd., H-200 SERIES), and silver colloidal particles in which silver nanoparticles were protected by a protective colloid (number average) The precipitate in which the particle diameter was aggregated was recovered. In addition, the particle size of the silver nanoparticles was measured with a transmission electron microscope (TEM).

  When the temperature of the dispersant (A2) is increased from 30 ° C. to 550 ° C. at a rate of 10 ° C. per minute with a thermogravimetric measurement device (TG / DTA, manufactured by Seiko Instruments Inc., EXSTAR 6000) When calculated from the mass reduction), it contained 2.0 parts by mass of the dispersant (A2) with respect to 100 parts by mass of silver, and the coagulant aid (A2-1) / polymer dispersant (A2-2) = 35. / 65. The (A2-1) / (A2-2) ratio is calculated by first calculating the amount of (A2-1) from the mass decrease from 30 ° C. to 200 ° C., and calculating the amount of (A2-2) by the formula [(A2) -(A2-1)] and obtained from these values (A2-1) and (A2-2).

(Paste preparation example 1)
51 parts by mass of silver colloidal particles prepared according to the above synthesis example, 50 parts by mass of silver filler (average particle size (D50) 1.6 μm), 10 parts by mass of terpineol (produced by Wako Pure Chemical Industries, Ltd., isomer mixture) To prepare a silver particle paste 1.

(Paste preparation examples 2 to 7)
In Preparation Example 1 of the paste, binder resin [mixture of bisphenol A type epoxy resin and modified polyamine curing agent, epoxy resin / curing agent (mass ratio) = 15/1] was further added to 0.5, 1, 2 respectively. 3, 5, 10 parts by mass were added to prepare silver pastes 2-7.

Examples 1-4
A polyethylene terephthalate (PET) substrate having a thickness of 150 μm is coated with an aqueous solution of an aqueous polyester resin having a resin concentration of 3 mass% by spin coating, and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.1 μm. Formed. Silver pastes 2 to 5 were screen-printed on this substrate and baked at 150 ° C. for 30 minutes to produce a baked film.

Examples 5-8
An aqueous layer of an aqueous polyester resin having a resin concentration of 15% by mass is applied to a polyethylene naphthalate (PEN) substrate having a thickness of 100 μm by spin coating, and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.5 μm. Formed. Silver pastes 2 to 5 were screen-printed on this substrate and baked at 170 ° C. for 30 minutes to produce a baked film.

Examples 9-11
An aqueous polyester resin solution having a resin concentration of 30% by mass was applied to a polyimide substrate having a thickness of 125 μm by spin coating, and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 1 μm. Silver pastes 2 to 4 were screen-printed on this substrate and fired at 200 ° C. for 30 minutes to produce a fired film.

Comparative Example 1
A fired film was produced in the same manner as in Example 1 except that the silver paste 1 was used in place of the silver paste 2.

Comparative Example 2
A fired film was produced in the same manner as in Example 5 except that the silver paste 1 was used instead of the silver paste 2.

Comparative Example 3
In Example 3, a fired film was produced without forming an adhesive layer.

Comparative Example 4
In Example 11, a fired film was produced without forming an adhesive layer.

  The volume resistivity (specific resistance) of the fired films obtained in these examples and comparative examples was measured. Also, the adhesion of the fired film was evaluated according to the JIS K 5600-5-6 cross-cut method, and the evaluation result was a grade 1 (peeling 5% or less) or less, and a grade 2 (peeling exceeded 5% and 15%). Less than%) was rated as Δ, and classification 3 (more than 15% but less than 35%) was marked as x. Further, a moisture resistance test was performed by exposing to a temperature of 85 ° C. and a humidity of 85% for 1000 hours, and “x” indicates that peeling was observed in a tape peeling test without a cross cut according to the cross cut method. The results are shown in Table 1.

  From the results shown in Table 1, the fired films of Examples 1 to 11 have high adhesion, and in particular, the fired films of Examples 1 to 3, 5 to 7, and 9 to 11 have high conductivity. In contrast, the fired film of the comparative example has low adhesion.

Example 12
An aqueous polyester resin solution having a resin concentration of 3% by mass was applied by spin coating on a silicon substrate having a thickness of 0.5 mm and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.1 μm. . Silver paste 3 was screen-printed on this substrate and baked at 150 ° C. for 30 minutes to produce a fired film having a thickness of 8.5 μm.

Example 13
An aqueous polyester resin solution having a resin concentration of 15% by mass was applied onto a glass substrate having a thickness of 1 mm by spin coating and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.5 μm. Silver paste 3 was screen-printed on this substrate and baked at 200 ° C. for 30 minutes to produce a 8.6 μm thick fired film.

Examples 14-15
An aqueous polyester resin solution having a resin concentration of 30% by mass was applied to a glass substrate having a thickness of 1 mm by spin coating, and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 1 μm. Silver paste 3 or 5 was screen-printed on this substrate and baked at 250 ° C. for 30 minutes to produce a baked film.

Examples 16-17
An aqueous polyester resin solution having a resin concentration of 30% by mass was applied to a glass substrate having a thickness of 1 mm by spin coating, and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 1 μm. Silver paste 6 or 7 was screen-printed on this substrate and baked at 300 ° C. for 30 minutes to produce a baked film.

Example 18
An aqueous polyester resin solution having a resin concentration of 30% by mass was applied to an alumina substrate having a thickness of 1 mm by spin coating, and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 1 μm. Silver paste 6 was screen-printed on this substrate and baked at 300 ° C. for 30 minutes to produce a baked film.

Comparative Example 5
A fired film was produced in the same manner as in Example 16 except that the silver paste 1 was used in place of the silver paste 6.

Comparative Example 6
In Comparative Example 5, a fired film was produced without forming an adhesive layer.

Comparative Example 7
In Example 2, a fired film was produced without forming an adhesive layer.

Reference example 1
A fired film was produced in the same manner as in Example 16 except that the paste firing temperature was changed to 350 ° C.

  The volume resistivity (specific resistance) of the fired films obtained in these examples, reference examples and comparative examples was measured, and the adhesion of the fired films was evaluated by the method described above. The results are shown in Table 2.

  From the results of Table 2, the fired films of Examples 12 to 18 have high adhesion, and in particular, the fired films of Examples 12 to 16 and 18 have high conductivity. In contrast, the fired films of the comparative example and the reference example have low adhesion.

Example 19
An aqueous polyester resin solution having a resin concentration of 8% by mass was applied to a carbon substrate having a thickness of 1 mm by spin coating and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.2 μm. Silver paste 3 was screen-printed on this substrate and baked at 160 ° C. for 30 minutes.

Example 20
An aqueous polyester resin solution having a resin concentration of 8% by mass was applied to a carbon substrate having a thickness of 1 mm by spin coating and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.2 μm. Silver paste 5 was screen-printed on this substrate and baked at 160 ° C. for 30 minutes.

Example 21
An aqueous polyester resin solution having a resin concentration of 4% by mass was applied to a carbon substrate having a thickness of 1 mm by spin coating and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.1 μm. Silver paste 3 was screen-printed on this substrate and baked at 160 ° C. for 30 minutes.

Example 22
An aqueous polyester resin solution having a resin concentration of 4% by mass was applied to a carbon substrate having a thickness of 1 mm by spin coating and dried at 120 ° C. for 30 minutes to form an adhesive layer having a thickness of about 0.1 μm. Silver paste 5 was screen-printed on this substrate and baked at 160 ° C. for 30 minutes.

Comparative Example 8
A fired film was produced in the same manner as in Example 19 except that the silver paste 1 was used in place of the silver paste 3.

Comparative Example 9
In Example 19, a fired film was produced without forming an adhesive layer.

Comparative Example 10
In Example 20, a fired film was produced without forming an adhesive layer.

  The surface resistance of the fired films obtained in these Examples and Comparative Examples was measured by the four-probe method, and the adhesion of the fired films was evaluated by the above-described method. The results are shown in Table 3.

  From the results of Table 3, the fired films of the examples have high adhesion and high conductivity. In addition, although there exists contribution of the resistance of a fired film, the resistance of a carbon substrate, and the contact resistance between both in surface resistance, it is a comparison with Example 19 and Comparative Example 9, and between Example 20 and Comparative Example 10. From the comparison, it was revealed that in Examples 19 and 20, high adhesion was obtained without the presence of the adhesive layer increasing the contact resistance between the fired film and the carbon substrate.

  The conductive substrate of the present invention includes various conductors such as a plasma display panel (PDP), a fluorescent display tube (VFD), a liquid crystal display (LCD), an organic electroluminescence display (ELD), etc., a touch panel type It can be used as an electrode such as a display device, an RFID tag, an electromagnetic wave shield, a conductive film used in a home or learning wiring kit, a conductive bonding agent, and the like.

Claims (9)

A method for producing a conductive substrate in which a laminate in which a coating film is formed on a substrate via an adhesive layer having a thickness of 0.1 to 10 μm is fired at 150 to 300 ° C. ,
The adhesive layer is composed of an aqueous polyester resin,
The coating film is composed of a conductive paste containing conductive particles, an epoxy resin and a dispersion medium,
Production in which the conductive particles include metal colloidal particles composed of metal nanoparticles and a dispersant in which an agglomeration aid and a polymer dispersant are combined, and the agglomeration aid is C _1-10 alkanoic acid. Way . Substrate, The method according to claim 1 Symbol mounting a substrate made of a polyester resin, polycarbonate resin or polyimide resin. The process according to claim 1 Symbol mounting substrate is a substrate composed of a polyethylene naphthalate resin. Substrate, glass, alumina, a manufacturing method of claim 1 Symbol mounting a substrate made of silicon or carbon. Conductive particles, The process according to any one of claims 1-4 further comprising a metal filler. 6. The method according to claim 5 , wherein the metal nanoparticles constituting the metal colloid particles are silver nanoparticles, and the metal filler is a silver filler. The production method according to any one of claims 1 to 6 , wherein a ratio of the epoxy resin is 0.1 to 5 parts by mass with respect to 100 parts by mass of the conductive particles. The manufacturing method according to any one of claims 1 to 7 , wherein the base material is composed of an organic material, and the ratio of the epoxy resin is 0.1 to 2 parts by mass with respect to 100 parts by mass of the conductive particles. The manufacturing method in any one of Claims 1-8 which bakes the laminated body in which the base material was comprised with the organic material at 150-200 degreeC.