JP5431071B2 - Conductive substrate, precursor thereof, and production method thereof - Google Patents

Description

  The present invention relates to a conductive substrate (metal composite film) having a metal film formed from a dispersion containing metal nanoparticles, a precursor thereof, and a method for producing the same.

  Currently, conductive paste such as silver paste is used for forming electrodes and circuits of electronic components and the like. These pastes are made by dispersing glass frit, inorganic oxide, etc. in a solvent in addition to metal powder. After forming this paste in a predetermined pattern by printing, it is heated at a temperature of 500 ° C. or higher. The organic components are burned off and the particles are sintered to form a conductor, and at the same time, a softened glass frit forms an adhesion layer at the interface between the substrate and the conductor to ensure adhesion.

  Problems with such pastes include the use of submicron metal powders with high sintering temperatures and the addition of glass frit to ensure adhesion, which necessitates high-temperature firing. In other words, it cannot be used in a portion where the heat-resistant temperature of the electrode, circuit, or substrate is low, and the presence of glass frit inhibits interparticle sintering and increases the specific resistance of the conductor.

  On the other hand, a paste using metal nanoparticles having a low sintering temperature can produce a conductor close to a bulk even at a firing temperature of 300 ° C. or lower. Adhesion to) is weak. Therefore, as a technique for improving such adhesion, a method of adding an additive such as an inorganic binder or an organic binder or performing a surface treatment on a substrate is also known. For example, Japanese Unexamined Patent Application Publication No. 2007-257869 (Patent Document 1) discloses a conductive ink containing metal fine particles, an inorganic binder, and a solvent, and the inorganic binder is made of a coupling agent or chelate containing Ti or Al. ing. However, such a technique requires a surface treatment of a binder or a substrate, and is not sufficient in terms of simplicity and economy. In particular, the addition of a binder may reduce the conductivity of the metal film.

  On the other hand, recently, there has been reported an example in which adhesion to glass or the like can be ensured without using an additive made of an organic or inorganic substance. For example, Japanese Patent Application Laid-Open No. 2007-294730 (Patent Document 2) discloses a method for forming a reflective conductive film comprising conductive metal nanoparticles and an organic solvent (polyhydric alcohol or the like) having a boiling point of 150 ° C. or higher. A reflective conductive film formed by applying a paint and forming a film is disclosed. In this document, the high-boiling solvent is gradually volatilized during the firing process to increase the density of the nanoparticles accumulated on the base material, and as a result, adhesion to the glass base material is ensured. However, in the method of this document, it has been reported that when the film thickness of the conductive film becomes 0.2 μm or more, the adhesion is deteriorated due to the internal stress generated when the nanoparticles are sintered to each other. However, it is difficult to form a relatively thick metal film and it is difficult to apply to various uses.

  JP-A-2008-81789 (Patent Document 3) has an organic protective layer made of an amine compound having a molecular weight of 100 to 1000 having one or more unsaturated bonds in one molecule on the surface of silver particles, A silver particle powder A having an average particle diameter DTEM measured by TEM observation of 50 nm or less, a fatty acid having a molecular weight of 100 to 1000, and an amine compound having a molecular weight of 100 to 1000, wherein at least one of the fatty acid and the amine compound is in one molecule. A silver particle composite powder in which a silver particle powder B having an organic protective layer, which is a compound having one or more unsaturated bonds, is mixed with silver particle powder B having an average particle diameter DTEM of 50 nm or less is obtained. Apply a dispersion of silver particle composite powder dispersed in a non-polar or small polar liquid organic medium at ˜300 ° C. to form a coating film on the substrate, After the coating film calcined silver film obtained by calcining is disclosed. In this document, “nonpolar or low polarity” means that the relative dielectric constant at 25 ° C. is 15 or less, more preferably 5 or less. It is described that when the relative dielectric constant exceeds 15, the dispersibility of the silver particles deteriorates and precipitates, which is not preferable. Specifically, isooctane, n-decane, isododecane, isohexane, n-undecane, n -It is described that hydrocarbon solvents such as aliphatic hydrocarbons such as tetradecane, n-dodecane, tridecane, hexane and heptane, and aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, decalin and tetralin can be suitably used. ing.

  In the method of this document, silver nanoparticles A that can produce a low-resistance conductor without adhesiveness to the substrate, and silver nanoparticles B that can produce a high-resistance conductor that has high adhesion to the substrate. It has been reported that a highly conductive and highly adhesive conductor can be produced by mixing a suitable amount of the above, dispersing it in a low-polarity solvent, applying it to a substrate, and baking it. However, in the method of this document, since the organic film considered to be involved in adhesion to a substrate such as glass remains in the formed silver film after firing, the silver nanoparticles are sintered. Becomes insufficient, and becomes higher than the specific resistance of the silver nanoparticle A alone. In addition, since an organic protective layer of fatty acid or amine is used as the adhesion layer, the adhesion strength is lowered when it is used for a long time at a high temperature, and it is difficult to maintain stable quality. In addition, since the solvent used in the dispersion is limited to low polar solvents such as toluene, it is difficult to apply a solvent such as water or alcohol. Furthermore, since it is necessary to produce and mix two types of silver nanoparticles separately, there is a problem that the number of man-hours increases.

JP 2007-257869 A (Claim 1) JP 2007-294730 A (claims, paragraph number [0029]) JP 2008-81789 A (claims, paragraph numbers [0017] to [0019])

  Therefore, the object of the present invention is to use a metal film (directly on an inorganic base material such as glass) directly on a base material without using a special additive (such as glass frit) or an easy-adhesion layer. In particular, it is to provide a conductive base material (metal composite film) capable of forming a conductive film), a precursor thereof, and a method for producing the same.

  Another object of the present invention is to provide a conductive base material, a precursor thereof, and a method for manufacturing the same, which can firmly fix a metal film to the base material with high adhesion even if it is a thick film.

  Still another object of the present invention is to provide a conductive substrate, a precursor thereof, and a method for producing the same, which can easily and reliably form a metal film having conductivity equivalent to or close to that of the bulk with respect to the substrate. There is to do.

  As a result of intensive investigations to achieve the above-mentioned problems, the present inventor has found that, in metal colloid particles, a protective colloid (or dispersant) that covers or protects metal nanoparticles, an organic compound having a carboxyl group, and a polymer dispersant (For example, a polymer dispersant having a carboxyl group) and using a dispersion (paste) containing such metal colloid particles, the substrate (particularly, an inorganic substrate such as glass) is used. Even without providing an easy-adhesion layer, it is possible to form a metal film directly on the substrate with high adhesion, and the formed metal film can be securely fixed even if the thickness is increased. As a result, the present invention was completed.

  That is, the precursor of the conductive base material (metal composite film or composite film or composite or metal laminate film) of the present invention is a conductive material composed of a base material and a coating film directly formed on the base material. A coating film (or dispersion liquid containing metal colloid particles), which is a precursor of a conductive substrate, and wherein the coating film is composed of metal nanoparticles and protective colloids covering the metal nanoparticles. And the protective colloid is a precursor of a conductive substrate composed of an organic compound having a carboxyl group and a polymer dispersant.

  The substrate may be an inorganic substrate (for example, a glass substrate). The metal constituting the metal nanoparticles may be a metal (for example, silver) containing at least a noble metal.

The organic compounds include aliphatic carboxylic acids (eg, C _1-24 aliphatic carboxylic acids, especially C _1-20 alkanoic acids) and hydroxycarboxylic acids [eg, aliphatic hydroxycarboxylic acids (eg, C _{14- 34} condensed polycyclic aliphatic hydroxycarboxylic acid etc.)] and the like.

The polymer dispersant may have a carboxyl group or an amino group, particularly a carboxyl group. Typically, the organic compound may be at least one selected from C _1-20 aliphatic carboxylic acid and aliphatic C _2-34 hydroxycarboxylic acid.

  In the metal colloidal particles, the ratio between the organic compound and the polymer dispersant is, for example, about the former / the latter (mass ratio) = 99/1 to 2/98 (for example, 84/16 to 4/96). There may be.

  Typically, the ratio of the protective colloid is about 1.0 to 60 parts by mass with respect to 100 parts by mass of the metal nanoparticles, and the ratio of the organic compound and the polymer dispersant is the former / the latter ( (Mass ratio) = 90/10 to 3/97 (for example, 84/16 to 4/96).

  The thickness of the coating film (thickness of the metal film after firing) may be 0.3 μm or more (for example, 0.3 to 100 μm). In the present invention, even with such a relatively thick film, a metal film having excellent metal properties (such as conductivity) can be reliably formed with high adhesion.

  According to the present invention, there is provided a dispersion comprising metal colloid particles composed of metal nanoparticles and protective colloids covering the metal nanoparticles on the substrate, wherein the protective colloids are organic compounds having a carboxyl group. A method of manufacturing a conductive substrate by coating a dispersion composed of a compound and a polymer dispersant and then heat-treating the obtained precursor to form a metal film is also included. The polar parameter of the solvent constituting the dispersion may be 3.1 to 10.2. In the present invention, even if such a polar solvent (water, alcohols, etc.) is used, a metal film can be formed with high adhesion. Further, the present invention includes a conductive substrate obtained by this method.

  In the precursor of the conductive base material (metal composite film) according to the present invention, the protective colloid constituting the metal colloid particles is composed of an organic compound having a carboxyl group and a polymer dispersant. By using a dispersion liquid (paste) containing a metal film (especially conductive material) directly on a substrate such as glass without using a special additive (glass frit, etc.) or via an easy adhesion layer. Film). Moreover, even if such a metal film is a thick film, the metal film can be firmly fixed to the inorganic substrate with high adhesion. In the present invention, by using a specific protective colloid, a metal film having conductivity equivalent to or close to the bulk can be easily and reliably formed on the base material.

  The conductive substrate (or conductive member or metal composite film) of the present invention is a conductive substrate composed of a substrate and a metal film directly formed on the substrate, and the metal film Is a conductive substrate (conductive film) which is a metal film (or sintered film) obtained by sintering a coating film containing metal colloidal particles composed of metal nanoparticles and a specific protective colloid covering the metal nanoparticles. Substrate). That is, such a metal film is usually a metal film (coating film) obtained by coating (coating) the dispersion liquid (paste) containing the metal colloidal particles on the base material, and usually metal nanoparticles. It is a film formed by sintering.

[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 inorganic material (inorganic material) or an organic material (organic material). Examples of inorganic materials include glasses (soda glass, borosilicate glass, crown glass, barium-containing glass, strontium-containing glass, boron-containing glass, low alkali glass, alkali-free glass, crystallized transparent glass, silica glass, and quartz glass. ), 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 oxide, strontium titanate, lead titanate, niobium titanate, calcium titanate, magnesium titanate, etc.), metal zirconates (barium zirconate, calcium zirconate, lead zirconate, etc.) etc.] It is done.

  Examples of the organic material include polymethyl methacrylate resin, styrene resin, vinyl chloride resin, polyester resin [including polyalkylene arylate resin (polyethylene terephthalate, etc.), polyarylate resin and liquid crystal polymer], Examples include polyamide resins, polycarbonate resins, polysulfone resins, polyethersulfone resins, polyimide resins, cellulose derivatives, and fluororesins.

  Since these materials are subjected to a firing step, they have high heat resistance materials such as inorganic materials, engineering plastics (for example, aromatic polyester resins (polyalkylene arylate resins such as polyethylene terephthalate, polyarylate resins, etc.), Polyimide resin, polysulfone resin, etc.), liquid crystal polymer, fluororesin and the like are preferable.

  In particular, in the present invention, a metal film can be formed with high adhesion even with an inorganic substrate (a substrate formed of an inorganic material).

  In addition, although the base material may be surface-treated, it is not normally surface-treated. In the present invention, a metal film can be formed even on a base material that has not been subjected to such surface treatment (easy adhesion treatment). That is, in the conductive substrate of the present invention, a metal film is usually formed directly on a substrate that has not been subjected to an easy adhesion treatment (particularly, an inorganic substrate).

  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.

[Metallic colloidal particles]
The metal colloid particles are metal colloid particles composed of metal nanoparticles and a protective colloid covering the metal nanoparticles, and the protective colloid is an organic compound having a carboxyl group and a polymer dispersant. It is composed of a combination of By using such metal nanoparticles coated with a protective colloid, a metal film can be formed with high adhesion even on a substrate that has not been surface-treated. In addition, since a special additive such as glass frit is not required and the sinterability of the metal nanoparticles is high, a metal film having electrical conductivity close to that of the bulk can be formed. In addition, the metal colloidal particles can increase the proportion of metal nanoparticles even though there are few coarse particles due to the combination of the specific protective colloids, and the storage stability of the metal colloidal particles (and dispersions thereof) is also improved. Are better.

  The reason for this is not clear, but the following reason can be considered. The protective colloid repeatedly adsorbs and desorbs on the surface of the metal nanoparticles on a short time scale. However, when the protective colloid is protected with a polymer dispersant, even if the adsorbed part is desorbed momentarily. The steric hindrance is large, and even when desorbed, other groups are adsorbed on the surface of the metal nanoparticle instead of the groups involved in the adsorption, so that aggregation and sintering between the particles hardly occur. Therefore, while exhibiting good storage stability, due to its high protective ability and decomposition temperature, the sintering of the metal nanoparticles does not occur unless the firing temperature is high. I can't get it. On the other hand, an organic compound having a carboxyl group usually has a weak adsorption force on the surface of metal nanoparticles, and often has a low vaporization temperature. Therefore, it is easy to obtain a low-resistance conductor by low-temperature firing, but metal nanoparticles are likely to agglomerate and sinter even at low temperatures such as room temperature, and the storage stability is not sufficient, so a metal film or the like is stably formed. Is difficult.

  Therefore, in the present invention, a polymer dispersant and an organic compound having a carboxyl group are combined. By such a combination, a portion where the polymer dispersant is adsorbed and a portion where the organic compound is adsorbed are formed on the surface of the metal nanoparticles. And, the portion where the polymer dispersant is adsorbed is stabilized by strong surface protection ability, and the storage stability is improved, while the portion where the organic compound is adsorbed 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 in an atmosphere of about room temperature, but starts a sintering reaction at a relatively low firing temperature (for example, several tens of degrees or more). It seems that a low-resistance metal film can be obtained even by low-temperature firing. If the firing temperature is higher, the collision between particles and the sinterability become higher than the protective ability of the polymer dispersant, so that the conductivity becomes comparable to the bulk. In addition, the polymer dispersant has an effect of improving the adhesion to the substrate, and in the conductive substrate of the present invention, the residual amount of such a polymer dispersant can be reduced and the volume shrinkage is small. In addition, since a film having high adhesion can be formed, these points are also factors that are excellent in adhesion to the base material, are firmly fixed to the base material, and can improve the conductivity of the metal film.

  Therefore, when such metal colloidal particles are used, the above metal film can be easily and reliably formed on the substrate.

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

  The metal nanoparticles may be the simple metal, the metal alloy, the metal oxide, the metal hydroxide, the metal sulfide, the metal carbide, the metal nitride, the metal boride and the like. These metal nanoparticles can be used alone or in combination of two or more. In many cases, the metal nanoparticles are usually single metal particles or metal alloy particles. Among them, the metal constituting the metal nanoparticles 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.

  Metal nanoparticles are nanometer-sized. For example, the average particle size (average primary particle size) of the metal nanoparticles in the metal colloid particles of the present invention is 1 to 100 nm, preferably 1.5 to 80 nm, more preferably 2 to 70 nm, and particularly about 3 to 50 nm. Or it may be about 1-40 nm (for example, 2-30 nm) normally.

  Further, the metal colloid particles of the present invention may contain almost no coarse particles. Therefore, the maximum primary particle diameter of the metal nanoparticles 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).

(Protective colloid)
The protective colloid is composed of an organic compound having a carboxyl group and a polymer dispersant.

(Organic compound having a carboxyl group)
The organic compound has a carboxyl group. 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). .

  Representative organic compounds 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).

  The organic compounds may be used alone or in combination of two or more.

Among these organic compounds, aliphatic carboxylic acid (for example, C _1-24 aliphatic carboxylic acid, preferably C _1-20 aliphatic carboxylic acid, more preferably C _1-18 aliphatic carboxylic acid), aliphatic Hydroxycarboxylic acids such as hydroxycarboxylic acids (aliphatic hydroxymonocarboxylic acids and aliphatic hydroxypolycarboxylic acids such as _C2-34 aliphatic hydroxycarboxylic acids) are preferred. Among aliphatic carboxylic acids, saturated aliphatic carboxylic acids (for example, C _1-24 alkanoic acids (alkane carboxylic acids) such as formic acid, acetic acid, propionic acid, stearic acid, preferably C _1-20 alkanoic acids, more preferably C _1-18 alkanoic acid) is preferred. Among the aliphatic hydroxycarboxylic acids, alicyclic hydroxycarboxylic acids (or hydroxycarboxylic acids having an alicyclic skeleton, for example, C _6-34 alicyclic hydroxycarboxylic acids such as cholic acid, preferably C _10-34 alicyclic hydroxycarboxylic acid, more preferably _C16-30 alicyclic hydroxycarboxylic acid) is preferable.

In addition, polycyclic aliphatic hydroxycarboxylic acids such as cholic acid (for example, condensed polycyclic aliphatic hydroxycarboxylic acids, preferably _C10-34 condensed polycyclic aliphatic hydroxycarboxylic acids, preferably _C14-34 condensed). Polycyclic aliphatic hydroxycarboxylic acids, more preferably _C18-30 condensed polycyclic aliphatic hydroxycarboxylic acids), dehydrocholic acid, colanic acid, and other polycyclic aliphatic carboxylic acids (eg, condensed polycyclic aliphatic acids) Aliphatic carboxylic acids, preferably C _10-34 condensed polycyclic aliphatic carboxylic acids, preferably C _14-34 condensed polycyclic aliphatic hydroxy carboxylic acids, more preferably C _18-30 condensed polycyclic aliphatic carboxylic acids ) polycyclic aliphatic carboxylic acids _{(e.g., C 10-50} condensed polycyclic aliphatic carboxylic acids such as, preferably _{C 12-40} condensed polycyclic aliphatic Carboxylic acid, more preferably C _14-34 condensed polycyclic aliphatic carboxylic acids, particularly C _18-30 condensed polycyclic aliphatic carboxylic acids), has a bulky structure, agglomeration of the metal nanoparticles It is preferable because of the large suppression effect.

  Furthermore, the organic compound having a carboxyl group can be used in the production process of colloidal particles because the produced colloidal particles are appropriately dispersed in a solvent and can form a sintered site by decomposition 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 organic compound 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 a sintered site.

Specifically, carboxylic acids having the above carbon number, such as formic acid, acetic acid, and propionic acid, have high affinity with the surface of the metal nanoparticles and are excellent in appropriate dispersibility (cohesiveness) and sinterability. C _1-10 alkanoic acids (alkanecarboxylic acids) such as butyric acid and valeric acid are preferred, C _1-6 alkanoic acids such as acetic acid and propionic acid (preferably C _1-4 alkanoic acids, more preferably C _2-3). Alkanoic acid, especially acetic acid) is more preferred. In particular, when _C1-4 alkanoic acid such as acetic acid is used, the colloidal metal particles are appropriately dispersed and agglomerated, so that generation of cracks and voids during combustion is suppressed, and a dense and hard fired film is formed. it can.

  The molecular weight of the organic compound is, for example, 1000 or less (for example, about 46 to 900), preferably 800 or less (for example, about 50 to 700), and more preferably 600 or less (for example, about 100 to 500). Also good.

  The pKa value of the organic compound may be, for example, 1 or more (for example, about 1 to 10), preferably about 2 or more (for example, about 2 to 8).

(Polymer dispersant)
The polymer dispersant (or polymer type dispersant) is not particularly limited as long as it can coat metal nanoparticles, but an amphiphilic polymer dispersant (or oligomer type dispersant) 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 polymer (gelatin, dextrin, arabic gum, casein, etc.), polyethylene sulfonic acid or salt thereof, polystyrene sulfonic acid or salt thereof, naphthalene Formalin condensate of sulfonic acid, nitrogen atom-containing polymer compound [for example, polymer compound having amino group such as polyalkyleneimine (polyethyleneimine, etc.), polyvinylpyrrolidone, polyallylamine, polyether polyamine (polyoxyethylene polyamine, etc.) ] Etc. are included.

  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 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 preferably has an acid group or a basic group, particularly a carboxyl group.

  In addition, when the polymer dispersant has an acid group (such as a carboxyl group), at least a part or all of the acid group (such as a carboxyl group) forms a salt (such as a salt with an amine or a metal salt). In particular, in the present invention, an acid group such as a carboxyl group (particularly, all carboxyl groups) is a salt [particularly a salt with a basic compound (a salt with an amine or an amine salt)]. The polymer dispersant [that is, the polymer dispersant having a free acid group (particularly, carboxyl group)] that does not form a polymer can be suitably used.

  In the polymer dispersant having an acid group (particularly a carboxyl group), the acid value is, for example, 1 mgKOH / g or more (for example, about 2 to 1500 mgKOH / g), preferably 3 mgKOH / g or more (for example, 4 to 1200 mgKOH / g). About 5 mg KOH / g (for example, about 8 to 1000 mg KOH / g), particularly 10 mg KOH / g or more (for example, about 12 to 900 mg KOH / 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 [manufactured by Avicia Co., Ltd.]; Dispersic 160, Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 164, Dispersic 166, Dispersic 170, Dispers 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 is, for example, 1,000 to 1,000,000 (for example, 1200 to 900,000), 1500 to 800,000, preferably 2000 to 700,000, more preferably 3000 to 500,000 (for example, 5000 to 300000), particularly 7000 to 700,000. It may be about 200,000.

  In the metal colloid particles, the ratio of the protective colloid (the total amount of the organic compound and the polymer dispersant) is, for example, 0.1 to 100 parts by mass (for example, 0.5 to 80 parts by mass) with respect to 100 parts by mass of the metal nanoparticles. Part), preferably 1.0 to 60 parts by mass (for example, 1.5 to 50 parts by mass), more preferably about 2 to 40 parts by mass (for example, 3 to 30 parts by mass). Particularly, in the metal colloid particles, the proportion of the protective colloid is 0.5 to 20 parts by mass (for example, 0.8 to 18 parts by mass), preferably 1 to 15 parts by mass with respect to 100 parts by mass of the metal nanoparticles. More preferably, it may be about 1.2 to 12 parts by mass (for example, 1.5 to 10 parts by mass). In the present invention, since the protective colloid is constituted by the specific combination, even a relatively small amount of the protective colloid as described above can be formed into metal nanoparticles with few coarse particles.

  In the metal colloidal particles, the ratio of the organic compound is, for example, 0.05 to 50 parts by mass (for example, 0.1 to 40 parts by mass), preferably 0.1 to 100 parts by mass of the metal nanoparticles. It may be about 2 to 30 parts by mass, more preferably about 0.3 to 20 parts by mass. In particular, in the metal colloid particles, the proportion of the organic compound is 0.05 to 10 parts by mass (for example, 0.1 to 8 parts by mass), preferably 0.12 to 7 parts by mass with respect to 100 parts by mass of the metal nanoparticles. Part (for example, 0.15 to 5 parts by mass), more preferably about 0.18 to 4 parts by mass (for example, 0.2 to 3 parts by mass).

  In the metal colloidal particles, the ratio of the polymer dispersant is, for example, 0.01 to 50 parts by mass, preferably 0.05 to 30 parts by mass, more preferably 100 parts by mass of the metal nanoparticles. About 0.1-30 mass parts (for example, 0.5-20 mass parts) may be sufficient. In particular, in the metal colloidal particles of the present invention, the proportion of the polymer dispersant is 0.05 to 15 parts by mass (for example, 0.1 to 12 parts by mass), preferably 0 with respect to 100 parts by mass of the metal nanoparticles. .12 to 10 parts by mass (for example, 0.15 to 8 parts by mass), more preferably about 0.18 to 7 parts by mass (for example, 0.2 to 6 parts by mass). In the present invention, the content of the polymer dispersant can be made relatively small as described above. Therefore, the residue of the organic substance derived from the polymer dispersant can be reduced by baking, and a highly conductive metal film can be obtained.

  Furthermore, in the metal colloidal particles, the ratio of the organic compound to the polymer dispersant (solid content when a solvent or the like is included) is the former / the latter (mass ratio) = 99/1 to 1/99 (for example, 98/2). To 1/99), for example, 97/3 to 1/99 (for example, 96/4 to 1/99), preferably 95/5 to 2/98 (for example, 93/7 to 2 /). 98), more preferably 92/8 to 3/97 (eg 90/10 to 3/97), in particular 87/13 to 3/97 (eg 86/14 to 4/96), usually 99/1 to It may be about 2/98 (for example, 99/1 to 5/95).

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

Other protective colloids include, for example, oxygen atom-containing organic compounds {eg, alcohols [eg, alkanols (C _6-20 alkane monools such as hexanol, octanol, decanol, dodecanol, octadecanol, etc.), cycloalkanols] (Cyclohexanol, etc.), alkanediols (ethylene glycol, propylene glycol, etc.), polyalkylene glycols (diethylene glycol, triethylene glycol, polyethylene glycol, etc.), aralkyl alcohols, polyhydric alcohols, etc.], ethers (cellosolves) , Carbitols, etc.), ketones [eg, alkanones, cycloalkanones, diketones (β-diketones such as acetylacetone)], esters (eg, fatty acid esters). Ethers, such as glycol ether esters), aldehydes (capryl aldehyde, lauryl aldehyde, palmitoyl aldehydes, C _6-20 aliphatic aldehydes such as stearyl aldehyde) such}, a sulfur atom-containing organic compound [e.g., sulfoxides, sulfones Acids (eg, arene sulfonic acids such as alkane sulfonic acid, benzene sulfonic acid, toluene sulfonic acid, etc.)] and the like. These other protective colloids may be used alone or in combination of two or more.

  The ratio of the other protective colloid is, for example, 0.1 to 100 parts by weight, preferably 0.5 to 50 parts by weight, and more preferably about 1 to 30 parts by weight with respect to 100 parts by weight of the protective colloid. Also good.

  The ratio of protective colloids (for example, (B1), (B2), etc.) in the metal colloid particles is measured by a conventional method, for example, thermal analysis (for example, thermal mass / differential thermal simultaneous analysis, etc.). be able to.

[Dispersion]
A dispersion for forming a coating film (a precursor of a metal film) on a substrate contains the metal colloid particles and a solvent. In addition, a solvent may be newly mixed, may be comprised with the solvent used in manufacture of the below-mentioned metal colloid particle, and may combine these.

  The solvent is not particularly limited as long as the metal colloid particles can be dispersed. Depending on the type of protective colloid, the solvent may be a polar solvent (water-soluble solvent) or a hydrophobic solvent (water-insoluble solvent). Also good.

Examples of polar solvents include water, alcohols [aliphatic alcohols (C _1-4 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, etc.), aliphatic polyhydric alcohols (ethylene glycol, diethylene glycol, polyethylene glycol, Glycerin, etc.], amides (formamide, acylamides such as acetamide, mono- or di-C _1-4 acylamides such as N-methylformamide, N-methylacetamide, N, N-dimethylformamide, N, N-dimethylacetamide etc.), ketones (such as acetone), ethers (dioxane, tetrahydrofuran, etc.), organic carboxylic acids (such as acetic acid), cellosolves (methyl cellosolve, C _1-4 alkyl cellosolve such as ethyl cellosolve Etc.), cellosolve acetates (C _1-4 alkyl cellosolve acetates such as ethyl cellosolve acetate), carbitol (methyl carbitol, ethyl carbitol, propyl carbitol, C _1-4 alkyl carbitol such as butyl carbitol And halogenated solvents (halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane) and the like. These polar solvents can be used alone or in combination of two or more. The polar parameters of these polar solvents are usually in the range of the polar parameters described later in many cases.

  Of these polar solvents, a polar solvent containing at least water may be used from the viewpoints of environmental conservation and simplicity. Furthermore, alcohol (especially aliphatic polyhydric alcohols such as glycerin) may be combined with water from the standpoint of suppressing evaporation of the solvent depending on the application. The proportion of alcohol is, for example, about 0.1 to 50 parts by mass, preferably 1 to 30 parts by mass, and more preferably about 3 to 20 parts by mass (particularly 5 to 15 parts by mass) with respect to 100 parts by mass of water. There may be.

  Examples of the hydrophobic solvent include hydrocarbons (aliphatic hydrocarbons such as hexane, trimethylpentane, octane, decane, dodecane, and tetradecane; alicyclic hydrocarbons such as cyclohexane; aromatic carbonization such as toluene and xylene. Hydrogens: halogenated hydrocarbons such as dichloromethane and trichloroethane), esters (such as methyl acetate and ethyl acetate), ketones (such as methyl ethyl ketone and methyl isobutyl ketone), ethers (such as diethyl ether and dipropyl ether) Can be illustrated. These hydrophobic solvents can be used alone or in combination of two or more.

  The solvent is preferably composed of at least a polar solvent (particularly a non-aromatic polar solvent or an aliphatic polar solvent). 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.

  In the present invention, as the solvent, water and water-soluble solvents (alcohols and the like) can be suitably used from the viewpoint that the environmental load is small and the handling is simple.

  In such a dispersion, the metal colloid particles (or metal nanoparticles) have high dispersibility in the solvent, and maintain such high dispersion stability over a long period of time. . And by using such a dispersion liquid, a metal film can be reliably formed with high adhesiveness with respect to a base material. The density | concentration of the metal nanoparticle in a dispersion liquid can be suitably selected according to the thickness etc. of a metal film, for example, 0.1-99 mass%, Preferably it is 1-95 mass%, More preferably, it is about 3-90 mass%. It may be. In particular, when the dispersion is used as a paste (paste-like dispersion), the concentration of the metal nanoparticles in the paste-like dispersion is, for example, 30 to 95% by mass, preferably 50 to 90% by mass, and more preferably. About 70-85 mass% may be sufficient. Such a dispersion (including a paste-like dispersion) is excellent in long-term stability (storage stability) without causing precipitation or the like even if it contains metal nanoparticles at such a high concentration. Therefore, for example, even if a metal film (sintered film) is formed after a dispersion (paste, etc.) is stored for a long period of time, excellent conductivity can be maintained without increasing the resistance value in the metal film.

  In the dispersion, the metal nanoparticles coated with the protective colloid are also nanometer-sized, and the average particle size (average primary particle size) can be selected from the same range as described above.

  In the dispersion, depending on the use, conventional additives such as binder resins (hydrophilic polymers such as polyvinyl alcohol and polyethylene glycol), colorants (dyeing pigments, etc.), hue improvers, dye fixing agents, Gloss imparting agent, metal corrosion inhibitor, stabilizer (antioxidant, UV absorber, etc.), surfactant or dispersant (anionic surfactant, cationic surfactant, nonionic surfactant, amphoteric surfactant) Agents), dispersion stabilizers, thickeners or viscosity modifiers, moisturizers, thixotropic agents, leveling agents, antifoaming agents, bactericides, fillers, and the like. These additives can be used alone or in combination of two or more.

  In addition, the solid content concentration of the metal nanoparticles (or the concentration of the metal nanoparticles in the metal colloid particles) with respect to the entire solid content constituting the dispersion is, for example, 50% by mass or more (for example, 55 to 99.5% by mass), Preferably it is 60 mass% or more (for example, 70-99 mass%), More preferably, it is 80 mass% or less (for example, 85-98.5 mass%), Usually 90-99 mass% may be sufficient.

[Method of producing metal colloidal particles and dispersion]
The metal colloid particles (or the dispersion liquid) are prepared by a conventional method, for example, a metal compound corresponding to the metal nanoparticles, a solvent in the presence of a protective colloid (and the other protective colloid if necessary) and a reducing agent. It can be prepared by reducing in

  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, the solvent constituting the dispersion may be used, or a solvent different from the solvent constituting the dispersion may be used. Specifically, the reaction solvent can be selected from the polar solvent and the hydrophobic solvent according to the type of the protective colloid. Usually, when the protective colloid is a water-soluble compound, a polar solvent such as water is used. Often 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 protective colloid is a water-insoluble compound, a hydrophobic solvent such as aliphatic hydrocarbons (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 protective colloid is constituted by the specific combination, as described above, even with a relatively small amount of protective colloid, it is possible to obtain a metal nanoparticle with few coarse particles. Without it, metal colloidal particles can be prepared. The obtained dispersion containing the metal colloid particles and the solvent may be used as the dispersion as it is, and the solvent used in the reaction is removed from the obtained dispersion containing the metal colloid particles and the solvent to obtain a new different solvent. (If necessary, other additives) may be added to prepare a new dispersion. Further, a new same or different solvent or additive may be added to the dispersion.

[Conductive substrate and method for producing the same]
The conductive base material (or metal composite film) of the present invention is composed of the base material (for example, an inorganic base material) and a metal film formed on the base material. It is the film | membrane (sintered film, sintering pattern) which sintered the coating film of the dispersion liquid containing a metal colloid particle.

  The thickness of the metal film (or the coating film after sintering) can be appropriately selected depending on the application, and is, for example, about 0.01 to 10000 μm, preferably about 0.1 to 500 μm, and more preferably about 0.5 to 100 μm. May be. 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, 0.8 to 80 μm), more preferably 1 μm or more (for example, 2 ˜50 μm), in particular, a metal film having a thickness of about 3 μm or more (for example, 5 to 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.

  Such a conductive substrate of the present invention sinters a precursor (coating film) obtained by coating (coating) at least the dispersion on the substrate to form a metal film (specifically, , The metal colloidal particles or the dispersion-derived metal film). Usually, such a metal film (sintered pattern, sintered film, sintered body layer, conductor layer) can be formed by further heat-treating (baking) a coating film (or pattern) formed by coating.

  The coating method of the dispersion is not particularly limited, and various methods such as a screen printing method, a flexographic printing method, a gravure printing method, a stamping method, a casting method, a dip method, a spin coating method, an electrophoresis method, a spray method, and an ink jet method are used. This method can be adopted.

  The heat treatment can be usually performed by heating (or baking or heat treatment) the coating film at a predetermined temperature. In addition, you may perform a drying process as needed prior to heat processing. The heat treatment temperature (firing temperature) is not particularly limited as long as the metal nanoparticles can be fused to form a continuous film, and is, for example, 50 to 700 ° C., preferably 80 to 500 ° C., more preferably about 100 to 400 ° C. It may be. In particular, since the metal colloidal particles are sintered even at a relatively low temperature, the heat treatment temperature is 450 ° C. or lower (for example, about 70 to 400 ° C.), preferably 100 to 350 ° C., more preferably 120 to 330. C (for example, 150 to 320 ° C.), usually about 100 to 350 ° C. may be used.

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

  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 1)
(I) Preparation of colloidal silver particles 66.8 g of silver nitrate, 10 g of acetic acid (manufactured by Wako Pure Chemical Industries, boiling point 118 ° C., carbon number 2) as an organic compound (B1) having a carboxyl group, and poly as a polymer dispersant (B2) 3.0 g of acrylic acid (manufactured by Wako Pure Chemical Industries, degree of polymerization 5000, acid value 780 mg KOH / 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.), followed by stirring with heating 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, H-200 SERIES), and silver colloidal particles in which silver nanoparticles were protected by a protective colloid (primary particle diameter of 1 to 100 nm, number The precipitate in which the average particle diameter was 20 nm) was collected. In addition, the particle size of the silver nanoparticles was measured with a transmission electron microscope (TEM).

(II) Dispersant Amount Measurement The amount of protective colloid (dispersant) (B) contained in the silver colloid particles is measured by TG-DTA (when the temperature is raised from 30 ° C. to 550 ° C. at a rate of 10 ° C. per minute. (Calculated from the mass reduction) of 5.3% by mass, and (B1) / (B2) (mass ratio) was 25/75. The ratio of (B1) / (B2) is calculated by first calculating the amount of (B1) from the mass decrease from 30 ° C. to 200 ° C., and calculating (B2) from (B)-(B1). I asked for it.

Example 1
Alkaline glass (manufactured by Matsunami Glass Co., Ltd., microslide) prepared by adding 80% silver paste prepared by adding ethylene glycol (polarity parameter 6.9) to the colloidal silver particles obtained in Synthesis Example 1. Glass, product number 3233) was applied using an applicator, pre-dried at 120 ° C. for 30 minutes, and baked at 300 ° C. for 30 minutes. The formed silver film had a thickness of 15 μm. The specific resistance was measured and found to be 2.1 μΩ · cm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. Also, the pencil hardness (the hardness of the core immediately before the surface of the film was scratched five times with a pencil core having different hardness and the film was “teared” or “peeled from the substrate”) was 7H or more.

(Example 2)
Alkali glass (product number 1737, manufactured by Corning Co., Ltd.) obtained by adding paste of 80% silver concentration prepared by adding ethylene glycol (polarity parameter 6.9) to the silver colloidal particles obtained in Synthesis Example 1 and cut to 5 × 5 cm. The film was applied using an applicator, pre-dried at 120 ° C. for 30 minutes, and baked at 300 ° C. for 30 minutes. The formed silver film had a thickness of 15 μm. The specific resistance was measured and found to be 2.1 μΩ · cm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher.

(Example 3)
Alumina substrate (manufactured by Kyocera, purity 96%) prepared by adding ethylene glycol (polarity parameter 6.9) to the silver colloidal particles obtained in Synthesis Example 1 and cutting the paste with a silver concentration of 80% into 5 × 5 cm The film was applied using an applicator, pre-dried at 120 ° C. for 30 minutes, and baked at 300 ° C. for 30 minutes. The formed silver film had a thickness of 15 μm. The specific resistance was measured and found to be 2.2 μΩ · cm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 5H or higher.

Example 4
A silver concentration 80% paste prepared by adding ethylene glycol (polarity parameter 6.9) to silver colloid particles is applied to a glass substrate using an applicator and baked at 150 ° C. or 250 ° C. for 30 minutes to obtain a specific resistance. Was measured. The paste was allowed to stand at room temperature for 6 months and then the specific resistance was measured in the same manner to evaluate the storage stability of the silver colloidal particle paste. The formed silver film had a thickness of 5 μm. The results are shown in Table 1. The amount of the dispersant was determined by the same method as in Synthesis Example 1. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher.

( Reference Example 5)
The same procedure as in Example 4 was conducted except that (B1) was propionic acid (manufactured by Wako Pure Chemical Industries, boiling point 141 ° C., carbon number 3). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

( Reference Example 6)
The same procedure as in Example 4 was performed except that (B1) was formic acid (manufactured by Wako Pure Chemical Industries, boiling point 100.7 ° C., carbon number 1). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

( Reference Example 7)
The same procedure as in Example 4 was performed except that (B1) was cholic acid (manufactured by Wako Pure Chemicals, decomposition temperature 198 ° C.). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

(Example 8)
(B2) Dispersic 190 (manufactured by Big Chemie, amphiphilic dispersant having a polyethylene oxide chain as a hydrophilic unit and an alkyl group as a hydrophobic unit, an acid value of 10 mgKOH / g, containing 60% water) The same operation as in Example 4 was performed except that the amount was 2 g. The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

( Reference Example 9)
(B2) was performed in the same manner as Reference Example 5 except that 7.2 g was used for Dispersic 190 (manufactured by Big Chemie, acid value 10 mgKOH / g, containing 60% water). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

( Reference Example 10)
The same procedure as in Reference Example 6 was performed except that 7.2 B was used for Dispersic 190 (produced by Big Chemie, acid value 10 mg KOH / g, containing 60% water). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

( Reference Example 11)
It was carried out in the same manner as in Reference Example 7 except that 7.2B was changed to Dispersic 190 (manufactured by Big Chemie, acid value 10 mg KOH / g, containing 60% water). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

(Example 12)
The same procedure as in Example 4 was performed except that (B2) was changed to 0.12 g of Dispersic 190 (manufactured by Big Chemie, acid value of 10 mg KOH / g, containing 60% water). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

(Example 13)
(B2) was carried out in the same manner as in Example 4 except that 0.72 g of Dispersic 190 (manufactured by Big Chemie, acid value 10 mg KOH / g, containing 60% water) was used. The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

(Example 14)
The same procedure as in Example 4 was performed except that 2.12 g of (B2) was changed to Disperbic 190 (manufactured by Big Chemie, acid value 10 mgKOH / g, containing 60% water). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

(Example 15)
The same procedure as in Example 4 was performed except that (B2) was changed to Dispersic 190 (produced by Big Chemie, acid value 10 mgKOH / g, water 60% contained) 5.04 g. The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

(Example 16)
(B2) was carried out in the same manner as in Example 4 except that 14.4 g of Dispersic 190 (manufactured by Big Chemie, acid value 10 mgKOH / g, containing 60% water) was used. The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1.

(Example 17)
The same procedure as in Example 4 was conducted except that (B1) was stearic acid (manufactured by Wako Pure Chemical Industries, boiling point 376 ° C., carbon number 18). The formed silver film had a thickness of 5 μm. When the tape peel test was performed by cross-cutting the silver film on the grid with 100 squares of 10 × 10 in total, it was not peeled off at 100/100 (that is, none of the squares were peeled off) and adhered firmly. It was. The pencil hardness was 7H or higher. The results are shown in Table 1. In addition, since the boiling point of stearic acid (B1) is 200 ° C. or more, and the mass reduction due to decomposition of (B2) and the boiling point of stearic acid (B1) overlap, the ratio of (B1) / (B2) is obtained. I couldn't.

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

Claims (6)

A conductive substrate precursor composed of a substrate and a coating film directly formed on the substrate,
The coating film is a coating film containing metal colloid particles composed of metal nanoparticles and a protective colloid coating the metal nanoparticles,
The proportion of the protective colloid is 1.0 to 60 parts by mass with respect to 100 parts by mass of the metal nanoparticles,
The protective colloid is composed of acetic acid and a polymer dispersant, and the ratio of acetic acid to the polymer dispersant is the former / the latter (mass ratio) = 86/14 to 4/96. Precursor.   The precursor of a conductive substrate according to claim 1, wherein the substrate is an inorganic substrate.   The conductive substrate precursor according to claim 1 or 2, wherein the metal constituting the metal nanoparticles is a metal containing at least a noble metal.   The precursor of the electroconductive base material in any one of Claims 1-3 in which a polymer dispersing agent has a carboxyl group or an amino group. A dispersion containing metal colloid particles composed of metal nanoparticles and protective colloids covering the metal nanoparticles on a substrate, wherein the proportion of the protective colloids is 100 parts by mass of the metal nanoparticles 1.0-60 mass parts, the protective colloid is composed of acetic acid and a polymer dispersant, and the ratio of acetic acid to the polymer dispersant is the former / the latter (mass ratio) = 86 / A method of manufacturing a conductive substrate by coating a dispersion of 14 to 4/96 and then heat-treating the obtained precursor to form a metal film. A conductive substrate obtained by the method according to claim 5 .