TW201700633A - Dispersion of inorganic particles - Google Patents

Abstract

The invention provides a dispersion of inorganic particles that has excellent dispersion stability and high viscosity, and can be calcined at a relatively low temperature. The features of a dispersion of inorganic particles provided by the invention include: inorganic particles having a short-chain amine with 6 or fewer carbon atoms on at least a portion of the surface; a polymer dispersant including a comb-shaped structural polymer which has a pigment affinity group in a backbone chain and/or a plurality of side chains and a plurality of side chains forming a solvation portion, a polymer which has a plurality of pigment affinity portions composed of a pigment affinity group in the backbone chain, or a straight chain polymer which has a pigment affinity portion composed of a pigment affinity group in a single end of the backbone chain; and a dispersion medium, wherein the dispersion medium includes a protective dispersant which has an acid value of 1 to 200, and an added amount of the protective dispersant is 0.1 wt% to 10 wt% or less, with respect to a solid component of the inorganic particles.

Description

Inorganic particle dispersion

The present invention relates to an inorganic particle dispersion containing metal particles, and more particularly to a metal part having excellent dispersion stability and preferably used for bonding at relatively low temperatures. A wiring of an electronic material or an inorganic particle dispersion in an electrode.

Conventionally, metal nanoparticles (or metal colloidal particles) having a high specific surface area and high reactivity have been known to have a property of melting (low-temperature sintering) at a low temperature as compared with a block or a metal atom, and it is expected to utilize this property. For example, it is applied to various fields in the form of an inorganic particle dispersion (conductive paste). Here, in order to expand the range of application of the inorganic particle dispersion in various printing methods, it is extremely important to adjust the viscosity of the inorganic particle dispersion.

For example, in the patent document 1 (Japanese Patent Laid-Open Publication No. 2009-097074), etc., a metal nanoparticle paste is proposed which comprises the metal nanoparticle (A) and the coated metal nanoparticle (A) A metal colloidal particle composed of the protective colloid (B) and a paste of a dispersion medium of the metal colloidal particles, and the protective colloid (B) contains an amine (B1) and a carboxylic acid (B2) having a carbon number of 4 or more.

In the metal nanoparticle paste of Patent Document 1, the coated metal nanoparticles are formed of a specific compound that acts as a binder, which is not easily adsorbed or decomposed at a low temperature, but is not an organic binder (resin binder). The protective colloid can thus form a sintered pattern at a low temperature by a screen printing method or a gravure printing method which forms a relatively thick film.

Further, in Patent Document 2 (Japanese Laid-Open Patent Publication No. 2010-150543), an ink composition comprising silver nanoparticles, a hydrocarbon solvent, and an alcohol co-solvent is provided, and the hydrocarbon solvent has at least five An aliphatic hydrocarbon having from carbon atoms to 20 carbon atoms or an aromatic hydrocarbon having from 7 carbon atoms to 18 carbon atoms, wherein the alcohol cosolvent is a terpineol solvent which is mostly α-terpineol by weight .

In the ink composition of Patent Document 2, silver nanoparticles are dissolved or dispersed in a mixture of a hydrocarbon solvent and an alcohol co-solvent, and by the improved ink stability and uniform printing characteristics, in addition to 60 μm can be achieved. In addition to the low line width, it can also be sprayed onto various substrate surfaces having different surface energies to obtain printed features. [Prior Art Document] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-097074 (Patent Document 2) Japanese Patent Laid-Open Publication No. 2010-150543

[Problems to be Solved by the Invention] However, in the metal nanoparticle paste described in Patent Document 1, the dispersion stability of the metal nanoparticles is not sufficiently ensured. Further, in the ink composition described in Patent Document 2, in order to disperse stability, it is necessary to use a hydrocarbon solvent (carbon number: 5 to 20) or an aromatic hydrocarbon such as dodecane, with the use of the hydrocarbons. Solvent, only low viscosity inks can be achieved.

Further, previously, as a method of increasing the viscosity of an ink composition containing metal nanoparticles, it is known to increase the concentration of the metal nanoparticles or to add a tackifier, but if the concentration of the metal nanoparticles is increased, the solvent The ratio is lowered to ensure printability or moisture retention. On the other hand, when a tackifier is added, the dispersibility of the metal nanoparticles and the conductivity of the ink composition are lowered.

In view of the above circumstances, an object of the present invention is to provide an inorganic particle dispersion which has excellent dispersion stability over a wide viscosity range (especially a high viscosity range) and can be calcined at a relatively low temperature.

Here, the usual ink for inkjet or reverse lithography is usually adjusted in a low viscosity range of 5 mPa·s to 15 mPa·s. That is, when the viscosity is 15 mPa·s or more, the ink used in the printing technique can be said to have high viscosity. [Means for solving the problem]

In order to achieve the above object, the inventors of the present invention have made an effort to study the composition of the inorganic particle dispersion or the dispersant, and have found that it is extremely effective to select an appropriate solvent, add a dispersant having an acid value, and the like. invention.

That is, the present invention provides an inorganic particle dispersion comprising: inorganic particles having a short-chain amine having a carbon number of 6 or less on at least a part of the surface; and a polymer dispersant contained in the main chain and/or a plurality of side chains a polymer having a comb-affinity group having a pigment affinity group and having a plurality of side chains constituting a solvation portion, a polymer having a plurality of pigment affinity portions containing a pigment affinity group in the main chain, or a linear polymer having a pigment affinity portion containing a pigment affinity group at one end of the chain; and a dispersion medium containing a protective dispersant having an acid value in the dispersion medium, the acid value of the protective dispersant The amount of the protective dispersant added is from 1 to 200, and is 0.1% by weight to 10% by weight or less based on the solid content of the inorganic particles.

Here, in the inorganic particle dispersion of the present invention, it is preferred that the short-chain amine comprises an alkylamine and/or an alkoxyamine, more preferably selected from the group consisting of butylamine, pentylamine, hexylamine, 2 In a group consisting of methoxyethylamine, 2-ethoxyethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, 4-methoxybutylamine At least one.

Since the inorganic particle dispersion of the present invention having the above-described structure contains a low molecular weight amine, it can be sintered at a low temperature, that is, it is excellent in low-temperature sinterability, and since it contains a polymer dispersant, it is excellent in dispersibility and can ensure long-term dispersion. stability. Further, by using a component which contributes to low-temperature sinterability (mainly an alkylamine having 6 or less carbon atoms) and a component which contributes to dispersion stability (mainly a polymer dispersant), the two components are adsorbed to the inorganic particles. The surface and show their respective properties. Further, as described above, by including the polymer dispersant, dispersion stability can be ensured, and in this respect, various physical property preparation agents can be added for general printing suitability.

By using at least a part of the amine present on the surface of the inorganic particles as a short-chain amine having 6 or less carbon atoms, at least a part of the amine adhering to the surface of the inorganic particles can be easily removed by heating, and the inorganic can be ensured. Good low-temperature sinterability of particles (metal particles) (for example, sinterability at 100 ° C to 350 ° C).

In addition, the polymer dispersant is a graft structure having a side chain of a solvent-binding portion in a side chain and having a side of a solvate portion (the polymer (1) having a comb structure described below); Since the main chain has a pigment affinity base (the following polymer (copolymer) (2) and the linear polymer (3)), the dispersibility of the colloidal particles containing the inorganic particles is good, and is preferable. It is used as a protective colloid for inorganic particles. By using the polymer dispersant, an inorganic particle dispersion (conductive ink and conductive paste) containing an inorganic particle dispersion containing inorganic particles at a high concentration can be obtained.

Further, the inorganic particle dispersion of the present invention is characterized by comprising a protective dispersant having an acid value added after synthesis of the inorganic particles (that is, a protective dispersant having an acid value for dispersing the inorganic particles). Here, the "protective dispersant having an acid value" is any dispersant including an adsorbent group or a functional group which does not have an amine value or a hydroxyl value. By using the protective dispersant, the dispersion stability of the inorganic particles in the solvent can be improved. The protective dispersant has an acid value of from 1 to 200, and preferably the dispersant has a functional group derived from phosphoric acid. The reason for the "protective dispersant having an acid value" is not necessarily clear, but the inventors believe that the adsorption can be carried out in a more dense form not only by adsorption to a metal but also by interaction with a short-chain amine. And has low-temperature sinterability and exhibits high dispersibility.

The reason is that if the acid value of the protective dispersant is 1 or more, the adsorption of the metal substance which coordinates with the amine and becomes alkaline on the surface of the particle starts to be caused by the acid-base interaction, and if it is 200 or less, it does not excessively It has an adsorption point and is therefore adsorbed in a preferred form. In addition, the reason is that by protecting the dispersant from having a functional group derived from phosphoric acid, phosphorus P interacts with the metal M via oxygen O, and thus is most effective for adsorption with a metal or a metal compound, and can be minimized as necessary. The amount of adsorption gives better dispersion. Here, the "acid value" is represented by the number of mg of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample. Examples of the method for measuring the acid value include an indicator method (p-naphthol benzene indicator) or a potentiometric titration method. ISO6618-1997: Neutralization test method by indicator titration → Corresponding to indicator titration (acid value) · ISO6619-1988: potentiometric titration (acid value) → corresponding to potentiometric titration (acid value)

Further, the amount of the protective dispersant to be added is 0.1% by weight to 10% by weight or less based on the solid content of the inorganic particles. When the content of the protective dispersant is 0.1% or more, the dispersion stability of the obtained inorganic particle dispersion becomes good, but when the content is too large, the low-temperature sinterability is lowered. From such a viewpoint, a more preferable content of the protective dispersant is 0.3% by mass to 10% by mass, and a more preferable content is 0.5% by mass to 8% by mass.

Further, in the inorganic particle dispersion of the present invention, the content of the dispersion medium is preferably from 1% by mass to 90% by mass. When the content of the dispersion medium is 1% by mass or more, stable dispersibility tends to be obtained, and when it is 90% by mass or less, the film formed of the ink tends to exhibit good conductivity. A more preferable content of the dispersion medium is 20% by mass to 80% by mass, and a more preferable content is 30% by mass to 70% by mass.

Further, in the inorganic particle dispersion of the present invention, it is preferred that the dispersion medium is selected from the group consisting of diethylene glycol dibutyl ether, isotridecyl alcohol, tetrahydronaphthalene, cyclohexylbenzene, terpineol, and indoline. Terpineol, terpene dihydroacetate, p-isopropyltoluene, pinene, pinane, limonene, isobornyl acetate, carveol, caryophyllene, anthraquinone At least one of the group consisting of pinoxyethanol and dihydrofurfuryloxyethanol.

The dispersion of the present embodiment is preferably a weight reduction ratio of 5% or less when heated from room temperature to 200 ° C by thermal analysis, and a weight reduction ratio of 10% or less when heated from 200 ° C to 500 ° C. Here, the weight reduction rate up to 200 ° C mainly indicates the content of a short-chain amine which is a low-temperature component which contributes to low-temperature sinterability, and the weight reduction rate at a high temperature of 200 ° C to 500 ° C mainly indicates dispersion. The stability of the acid value of the dispersant content. If the short-chain amine or the high-temperature component is excessive, the low-temperature sinterability is impaired. In other words, when the weight loss rate when heating from room temperature to 200 ° C is 5% or less and the weight loss rate when heating from 200 ° C to 500 ° C is 10% or less, the low-temperature sintering property is further excellent.

Further, in the inorganic particle dispersion of the present invention, it is preferred that the dispersion medium contains 0.5% by mass to 10% by mass of a fatty acid having a boiling point of 150 ° C or higher, and more preferably the fatty acid is selected from the group consisting of stearic acid and oleic acid. At least one of the group consisting of linoleic acid, linoleic acid, and ricinoleic acid. By including a fatty acid in the dispersion medium, the melting rate (calcination rate) of the inorganic particles (metal particles) can be moderately delayed, and the balance between the volatilization of the organic component and the melting of the metal particles can be obtained, and the strength is stronger and stronger. Bonding layer. [Effects of the Invention]

According to the present invention, it is possible to provide an inorganic particle dispersion which has excellent dispersion stability and high viscosity and can be calcined at a relatively low temperature.

Hereinafter, a preferred embodiment of the inorganic particle dispersion of the present invention will be described in detail. In the following description, the embodiment of the present invention is not limited thereto, and the repeated description may be omitted.

The inorganic particle dispersion of the present embodiment includes: inorganic particles having a short-chain amine having 6 or less carbon atoms on at least a part of the surface; and a polymer dispersant comprising pigment affinity in the main chain and/or the plurality of side chains. A polymer having a comb structure having a plurality of side chains constituting a solvation moiety, a polymer having a plurality of pigment affinity portions containing a pigment affinity group in the main chain, or a single end of the main chain a linear polymer having a pigment affinity portion of a pigment affinity group; and a dispersion medium containing a protective dispersant having an acid value in the dispersion medium, wherein the protective dispersant has an acid value of from 1 to 200, The amount of the protective dispersant to be added is 0.1% by weight to 10% by weight or less based on the solid content of the inorganic particles.

As described above, the inorganic particle dispersion adds a protective dispersant having an acid value not only in the synthesis of the inorganic particles but also in a dispersion medium (particularly a high-viscosity dispersion medium) in which the inorganic particles are dispersed. Thereby, the dispersibility of the inorganic particles is remarkably improved. In addition, it has good low temperature sintering.

In order to form the viscosity of the inorganic particle dispersion to a high viscosity (15 mPa·s or more), a terpene-based material which is a high-viscosity or high-boiling solvent is preferably used as a dispersion medium. However, since the functional group (OH group or the like) of the terpene-based material of the inorganic particles dispersed in the organic solvent tends to destabilize the particles, it is difficult to use the terpene-based material alone or as a main solvent.

On the other hand, in the inorganic particle dispersion of the present embodiment, various studies have been made on the polymer dispersant, and a small amount of a polymer dispersant (protective dispersant) having an acid value is added after the production of the inorganic particles. The dispersibility of the inorganic particles is drastically improved while maintaining conductivity. Here, even if a protective dispersant having no acid value is used, the dispersibility is not improved, and when the acid value is too high, the effect is not obtained in the same manner.

It is considered that the protective dispersant having an acid value can adsorb not only by adsorption to inorganic particles but also by interaction with short-chain amines, and exhibits high dispersibility in a more dense form. Further, the reason why the dispersibility of the polymer dispersant having an acid value in the terpene-based material (dispersion medium) is not necessarily clarified, but the protective dispersant is added afterwards to protect the dispersant from being adsorbed on the solvent without being adsorbed to the inorganic particles. in. Here, it is considered that the protective dispersant that floats has a large effect of suppressing aggregation of inorganic particles in a high-viscosity dispersion medium which is a terpene-based material, and contributes greatly to dispersion stability of inorganic particles. Further, when the protective dispersant is not added afterwards, the cleaning dispersant adsorbed on the inorganic particles is removed by the washing operation during the precipitation purification, so that the floating protective dispersant does not substantially exist.

It is preferred to add the protective dispersant to the dispersion medium in advance, or to add the inorganic particles after dispersing the dispersion medium in the dispersion medium. Further, the method of adding the protective dispersant to the dispersion medium is not particularly limited, and may be added by various methods known in the art.

The inorganic particle dispersion of the present embodiment preferably has a weight reduction rate of 5 mass% or less when heated from room temperature to 200 ° C by thermal analysis, and a weight reduction rate of 10 mass when heated from 200 ° C to 500 ° C. %the following. Here, the weight reduction rate up to 200 ° C mainly indicates the content of a low-temperature component (mainly a short-chain amine having a carbon number of 6 or less) which contributes to low-temperature sinterability, and the weight reduction rate at 200 ° C to 500 ° C mainly indicates A high-temperature component (mainly a polymer dispersant) that contributes to dispersion stability.

When the low temperature component is excessive, the dispersion stability is impaired, and if the high temperature component is excessive, the low temperature sinterability is impaired. In other words, when the weight loss rate is 5% by mass or less when heated from room temperature to 200 ° C, the dispersion stability is further excellent, and when the weight loss rate when heating from 200 ° C to 500 ° C is 10% by mass or less, the temperature is low. Sinterability is more excellent.

In the inorganic particle dispersion of the present embodiment, metal colloidal particles obtained by colloidalizing inorganic particles (metal particles) to be described later are contained as a main component, and examples of the form of the metal colloidal particles include organic substances attached to metal particles. The metal colloidal particles which are formed by a part of the surface, the metal colloidal particles which are formed by coating the surface of the metal particles with the organic substance, and the metal colloidal particles which are formed by mixing them are not particularly limited. Among them, metal colloidal particles composed of metal particles as a core and coated with an organic substance are preferably used. Those skilled in the art can suitably prepare metal colloidal particles having the morphology described using techniques well known in the art.

The inorganic particle dispersion of the present embodiment is a fluid containing a colloidal particle containing a metal particle and an organic substance as a main component, and may contain an organic substance or a dispersion medium which does not constitute a metal colloidal particle, in addition to the metal particle and the organic substance constituting the metal colloidal particle. Or residual reducing agent, etc.

As a method of applying the inorganic particle dispersion of the present embodiment to a substrate, for example, self-immersion, screen printing, spray method, bar coating method, spin coating method, inkjet method, dispenser method, needle transfer method, The press method, the coating method by the bristles, the casting method, the flexographic method, the gravure method, the lithography method, the transfer method, the hydrophilic hydrophobic pattern method, or the syringe method are appropriately selected and used.

The viscosity can also be adjusted by adjusting the particle diameter of the metal particles, adjusting the content of the organic substance, adjusting the amount of addition of other components of the dispersion medium, adjusting the blending ratio of each component, and adding a tackifier. The viscosity of the inorganic particle dispersion of the present embodiment can be measured by a cone plate viscometer (for example, a rheometer MCR301 manufactured by Anton Paar Co., Ltd.).

Hereinafter, each component of the inorganic particle dispersion of the present embodiment will be described in more detail.

(1-1) Inorganic particles (metal particles) The inorganic particles of the inorganic particle dispersion of the present embodiment are not particularly limited, and examples thereof include gold, silver, copper, nickel, ruthenium, tin, iron, and platinum groups. At least one of the elements (钌, 铑, palladium, iridium, osmium, and platinum). As the metal, particles of at least one metal selected from the group consisting of gold, silver, copper, nickel, ruthenium, tin or a platinum group element are preferred, and copper or ionization tends to be less than copper (preferably) A noble metal, that is, at least one of gold, platinum, silver, and copper. These metals may be used singly or in combination of two or more. As a method of use in combination, there may be a case where alloy particles containing a plurality of metals are used, or a case where metal particles having a core-shell structure or a multilayer structure are used.

For example, when silver particles are used as the inorganic particles of the inorganic particle dispersion, the conductivity of the coating layer (coating film) formed using the inorganic particle dispersion of the present embodiment is good, but migration is considered (migration). The problem is that migration can be difficult to occur by using an inorganic particle dispersion containing silver and other metals. As the "other metal", a metal having a higher ionization sequence than hydrogen, that is, gold, copper, platinum, or palladium is preferable.

The average particle diameter of the metal particles (or metal colloidal particles) in the inorganic particle dispersion of the present embodiment is not particularly limited as long as it does not impair the effects of the present invention, and it is preferred to have an average particle such as a decrease in melting point. The diameter may be, for example, 1 nm to 200 nm. Especially preferred is 2 nm to 100 nm. When the average particle diameter of the metal particles is 1 nm or more, an inorganic particle dispersion which can form a favorable coating film is obtained, and the production cost of the metal particles is not high and practical. Moreover, when it is 200 nm or less, it is difficult to change the dispersibility of a metal particle over time, and it is preferable.

In addition, it is also possible to add micron-sized metal particles as needed. In this case, the metal particles of a nanometer size lower the melting point around the micron-sized metal particles, whereby a good conductive path can be obtained.

The present inventors have found that, in particular, a metal particle having a small particle diameter which exhibits a decrease in melting point is used, and an inorganic particle dispersion containing at least a part of the surface of the metal particle is attached, by a specific temperature The weight reduction rate at the time of heating in the range is optimally set to a specific range, and the low-temperature sinterability and the dispersion stability balance are improved as compared with the inorganic particle dispersion which is not.

Further, the particle diameter of the metal particles in the inorganic particle dispersion of the present embodiment may not be fixed. In addition, when the inorganic particle dispersion contains a dispersion medium, a resin component, a thickener, a surface tension adjuster, and the like to be described as an optional component, the metal colloidal particle component having an average particle diameter of more than 200 nm may be used. A component which does not cause aggregation or does not significantly impair the effects of the present invention may contain a particle component having the average particle diameter of more than 200 nm.

Here, the particle diameter of the metal particles in the inorganic particle dispersion of the present embodiment can be measured by a dynamic light scattering method, a small-angle X-ray scattering method, or a wide-angle X-ray diffraction method. In order to show a decrease in the melting point of the metal particles having a nanometer size, a crystal diameter determined by a wide-angle X-ray diffraction method is suitable. For example, in the wide-angle X-ray diffraction method, more specifically, RINT-Ultima III manufactured by Rigaku Electric Co., Ltd. can be used to measure in a range of 30 to 80 in 2θ by a diffraction method. In this case, the sample may be measured by stretching thinly on the glass plate having a depression having a depth of about 0.1 mm to 1 mm at the center portion so as to have a flat surface. Further, as long as the crystal diameter (D) is used as the particle diameter, the crystal diameter (D) is JADE manufactured using a magnetic motor, and the half width of the obtained diffraction spectrum is substituted. It is calculated by the Scherrer formula. D = Kλ / Bcos θ Here, K: Shera constant (0.9), λ: wavelength of X-ray, B: full width at half maximum of ray, θ: Bragg angle.

(1-2) Short-chain amine having a carbon number of 6 or less In the inorganic particle dispersion of the present embodiment, a short-chain amine having 6 or less carbon atoms is attached to at least a part of the surface of the inorganic particles. Further, on the surface of the inorganic particles, a trace amount of an organic substance which is first contained as an impurity in the raw material, a trace amount of an organic substance which is mixed in a production process to be described later, a residual reducing agent which is not completely removed during the cleaning process, a residual dispersant, or the like In a way, a small amount of organic matter can be attached.

The short-chain amine is not particularly limited as long as it has 6 or less carbon atoms, and may be linear or branched, or may have a side chain, and preferably contains an alkylamine and/or an alkoxy group. The amine, more preferably selected from the group consisting of butylamine, pentylamine, hexylamine, 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxypropylamine, 3-ethoxyl At least one of the group consisting of propylamine and 4-methoxybutylamine.

The short-chain amine may be, for example, a compound containing a functional group other than an amine such as a hydroxyl group, a carboxyl group, an alkoxy group, a carbonyl group, an ester group or a mercapto group. Further, the amines may be used alone or in combination of two or more. Further, the boiling point under normal pressure is 300 ° C or lower, and particularly preferably 250 ° C or lower.

In the range of the inorganic particle dispersion of the present embodiment, which does not impair the effects of the present invention, a carboxylic acid may be contained in addition to the short-chain amine having 6 or less carbon atoms. The carboxyl group in one molecule of the carboxylic acid has a relatively high polarity, and an interaction due to hydrogen bonding is liable to occur, but a portion other than the functional group has a relatively low polarity. Further, the carboxyl group is liable to exhibit acidic properties. Further, when the carboxylic acid is localized (adhered) to at least a part of the surface of the inorganic particles (that is, at least a part of the surface of the inorganic particles coated) in the inorganic particle dispersion of the present embodiment, the solvent and the inorganic particles can be sufficiently obtained. Affinity, and can prevent aggregation of inorganic particles with each other (improves dispersibility).

As the carboxylic acid, a compound having at least one carboxyl group can be widely used, and examples thereof include formic acid, oxalic acid, acetic acid, caproic acid, acrylic acid, caprylic acid, and oleic acid. A part of the carboxyl group of the carboxylic acid may form a salt with the metal ion. Further, regarding the metal ions, two or more kinds of metal ions may be contained.

The carboxylic acid may be, for example, a compound containing a functional group other than a carboxyl group such as an amino group, a hydroxyl group, an alkoxy group, a carbonyl group, an ester group or a fluorenyl group. In this case, the number of carboxyl groups is preferably at least the number of functional groups other than the carboxyl group. Further, the carboxylic acids may be used alone or in combination of two or more. Further, the boiling point under normal pressure is 300 ° C or lower, and particularly preferably 250 ° C or lower. Additionally, the amine forms a guanamine with the carboxylic acid. The guanamine group is also moderately adsorbed on the surface of the inorganic particles, so that the amide group can be attached to the surface of the inorganic particles.

When the inorganic particles and the organic substance adhering to the surface of the inorganic particles (the short-chain amine having a carbon number of 6 or less) constitute a colloid, the content of the organic component in the colloid is preferably 0.5% by mass to 50%. quality%. When the content of the organic component is 0.5% by mass or more, the storage stability of the obtained inorganic particle dispersion tends to be good, and when it is 50% by mass or less, the conductive body of the inorganic particle dispersion is heated. Good tendencies. A more preferable content of the organic component is 1% by mass to 30% by mass, and a more preferable content is 2% by mass to 15% by mass.

(1-3) Polymer dispersing agent The polymer dispersing agent contained in the inorganic particle dispersion of the present embodiment is a graft structure in which a pigment affinity group is present in a side chain and has a side chain constituting a solvating portion. The polymer (1)) having a comb structure; and the polymer affinity base (the polymer (copolymer) (2) and the linear polymer (3) described below) in the main chain. Therefore, the colloidal particles containing the inorganic particles have good dispersibility, and are preferably used as a protective colloid for the inorganic particles. By using the polymer dispersant, an inorganic particle dispersion containing an inorganic particle dispersion containing inorganic particles at a high concentration can be obtained.

In the above-mentioned polymer dispersant, the term "pigment affinity group" means a functional group having a strong adsorption force to the surface of the pigment containing the inorganic particles, and examples thereof include a tertiary amino group and a quaternary ammonium salt. a heterocyclic group having a basic nitrogen atom, a hydroxyl group, a carboxyl group or the like. In the present invention, the pigment affinity group exhibits a strong affinity for metal particles. Since the high molecular weight pigment dispersant has the pigment affinity group, it can sufficiently exhibit performance as a protective colloid of metal particles.

The polymer (1) of the comb structure is a structure in which a plurality of side chains having the pigment affinity group and a plurality of side chains constituting a solvating moiety are bonded to a main chain, and the sides are The chain is keyed to the main chain as if it were a comb. In the present specification, the structure is referred to as a comb structure. In the polymer (1) of the comb structure, the pigment affinity group is not limited to the side chain end, and may be present in a large amount in the side chain or in the main chain. Further, the solvating moiety is a moiety having affinity for a solvent and is referred to as a hydrophilic or hydrophobic structure. The solvating moiety includes, for example, a water-soluble polymeric chain, a lipophilic polymeric chain, and the like.

The polymer (1) having the above-described comb-shaped structure is not particularly limited, and examples thereof include one or more poly(carbonyl-C ₃ -C ₆ - groups disclosed in Japanese Laid-Open Patent Publication No. Hei 5-177123. An alkoxy) chain, and comprising 3 to 80 carbonyl-C ₃ -C ₆ -alkylalkoxy groups in each of the chains and bonded to the poly(ethylene) by a guanamine or a base crosslinking group A poly(ethyleneimine) or an acid salt thereof having a structure of an amine; a poly(lower alkylene)imine comprising a poly(lower alkylene)imide and a poly(carboxylic acid group) having a free carboxylic acid group as disclosed in Japanese Laid-Open Patent Publication No. SHO 54-37082 a reaction product of an ester, and at least two polyester linkers are bonded to each poly(lower alkylene) imine linkage; the amine compound is averaged as disclosed in Japanese Patent Publication No. Hei 7-24746 A pigment dispersant obtained by reacting a carboxyl group-containing prepolymer having a molecular weight of 300 to 7,000 with a high molecular weight epoxy compound having an epoxy group at the terminal or in an arbitrary order.

The polymer (1) of the comb structure preferably has two to 3,000 pigment affinity groups in one molecule. If it is less than 2, the dispersion stability is not sufficient, and if it exceeds 3,000, the viscosity is too high to be handled, and the particle size distribution of the colloidal particles containing the metal particles is wider than necessary and the dispersion stability is lowered. Happening. More preferably 25 to 1500.

The polymer (1) of the comb structure preferably has two to 1000 side chains constituting a solvating moiety in one molecule. If it is less than 2, the dispersion stability is not sufficient, and if it exceeds 1,000, the viscosity is too high and it is difficult to handle, and the particle size distribution of the colloidal particles containing the metal particles is wider than necessary and the dispersion stability is lowered. . More preferably 5 to 500.

The polymer (1) of the comb structure preferably has a number average molecular weight of from 2,000 to 1,000,000. When it is less than 2,000, the dispersion stability is not sufficient. When it exceeds 1,000,000, the viscosity is too high and it is difficult to handle, and the particle size distribution of the colloidal particles containing the metal particles is wider than necessary and the dispersion stability is lowered. More preferably, it is 4,000 to 500,000.

The polymer (copolymer) (2) having a plurality of pigment affinity portions containing a pigment affinity group in the main chain is one in which a plurality of pigment affinity groups are disposed along a main chain, for example, the pigment affinity group For those who hang from the main chain. In the present specification, the pigment affinity portion means a portion in which one or more of the pigment affinity groups are present and functions as an anchor adsorbed on the surface of the pigment containing the inorganic particles.

As the copolymer (2), for example, a mixture of a polyisocyanate, a monohydroxy compound, a monohydroxymonocarboxylic acid compound or a monoaminomonocarboxylic acid compound disclosed in Japanese Laid-Open Patent Publication No. Hei-4-210220, And a reaction product of a compound having at least one basic ring nitrogen and an isocyanate-reactive group; JP-A-60-16631, JP-A-2002-612, and JP-A-63-241018 A polymer having a plurality of tertiary amino groups or a group having a basic cyclic nitrogen atom suspended in a main chain comprising a polyurethane/polyurea disclosed in Japanese Patent Application Laid-Open No. Hei 1-279919 a copolymer comprising a steric stabilizing unit having a water-soluble poly(oxyalkylene) chain, a structural unit, and a unit containing an amine group, wherein the unitary unit containing an amine group contains a tertiary amino group or an acid thereof a base of a salt or a quaternary ammonium group, and contains 0.025 milliequivalent to 0.5 milliequivalent of an amine group per 1 g of the copolymer; the following amphiphilic medium disclosed in Japanese Patent Laid-Open No. Hei 6-100642 Polymer, etc., which is An amphiphilic copolymer comprising a backbone and a stabilized oxime unit, the backbone comprising an addition polymer, the stabilized oxime unit comprising at least one C1-C4 alkoxy polyethylene or polyethylene-co-propylene glycol ( a methyl acrylate having a weight average molecular weight of 2,500 to 20,000, wherein the amphiphilic polymer contains up to 30% by weight of a non-functional structural unit in the main chain, and a stability of up to 70% by weight in total And a functional unit which is a substituted or unsubstituted styrene-containing unit, a hydroxyl group-containing unit, and a carboxyl group-containing unit, and a hydroxyl group and a carboxyl group, a hydroxyl group, a styryl group, and a hydroxyl group. The ratio of the propyleneoxy group or the ethyleneoxy group is 1:0.10 to 26.1; 1:0.28 to 25.0; 1:0.80 to 66.1, respectively.

The copolymer (2) is preferably one having from 2 to 3,000 pigment affinity groups in one molecule. When the amount is less than two, the dispersion stability is not sufficient. When the number is more than 3,000, the viscosity is too high to be handled, and the particle size distribution of the colloidal particles containing the inorganic particles is wider than necessary and the dispersion stability is lowered. Happening. More preferably 25 to 1500.

The copolymer (2) preferably has a number average molecular weight of from 2,000 to 1,000,000. When it is less than 2,000, the dispersion stability is not sufficient. When it exceeds 1,000,000, the viscosity is too high and it is difficult to handle, and the particle size distribution of the colloidal particles containing the inorganic particles is wider than necessary and the dispersion stability is lowered. More preferably, it is 4,000 to 500,000.

The linear polymer (3) having a pigment affinity portion containing a pigment affinity group at a single end of the main chain has a pigment affinity portion containing one or more pigment affinity groups only at one end of the main chain. But for those who have sufficient affinity for the pigment surface.

The linear polymer (3) is not particularly limited, and examples thereof include an AB block type polymer which is basic as disclosed in JP-A-46-7294; The AB block type polymer in which the aromatic carboxylic acid is introduced into the A block disclosed in the specification of the patent No. 4656226; and the AB block type which is a basic functional group having a single terminal disclosed in the specification of U.S. Patent No. 4,032,698 Molecular; an AB-block type polymer having a single-terminal acidic functional group disclosed in the specification of U.S. Patent No. 4,070, 388, which is incorporated in the specification of U.S. Patent No. 4, 656, 226, which is incorporated herein by reference. The weather resistance yellowing of the AB block type polymer in which the aromatic carboxylic acid is introduced into the A block is improved.

The linear polymer (3) preferably has two to 3,000 pigment affinity groups in one molecule. When the amount is less than two, the dispersion stability is not sufficient. When the number is more than 3,000, the viscosity is too high to be handled, and the particle size distribution of the colloidal particles containing the inorganic particles is wider than necessary and the dispersion stability is lowered. Happening. More preferably 5 to 1500.

The linear polymer (3) preferably has a number average molecular weight of 1,000 to 1,000,000. When it is less than 1,000, the dispersion stability is not sufficient. When it exceeds 1,000,000, the viscosity is too high and it is difficult to handle, and the particle size distribution of the colloidal particles containing the inorganic particles is wider than necessary and the dispersion stability is lowered. More preferably, it is 2,000 to 500,000.

A commercially available one can also be used as the polymer dispersant. As the commercial item, for example, SOLSPERSE 11200, SOLSPERSE 13940, SOLSPERSE 16000, SOLSPERSE 17000, Sonupa SOLSPERSE 18000, SOSOLERS 20,000, SOLSPERS 24000, SOLSPERS 26000, SOLSPERSE 27000, SOSOLERS 28000 (made by Lubrizol (share)); DISPERBYK 102, DISPERBYK 110, DISPERBYK 111, DISPARK ( DISPERBYK) 142, DISPERBYK 160, DISPERBYK 161, DISPERBYK 162, DISPERBYK 163, DISPARK ( DISPERBYK) 166, DISPERBYK 170, DISPERBYK 174, DISPERBYK 180, DISPERBYK 182, DISPARK ( DISPERBYK) 184, DISPERBYK 190, Despabike ( DISPERBYK) 2155, BYK-P104, BYK-P105 (made by BYK-Chemie Japan); Efka (EFKA)-46, Efka (EFKA)-47, Evka ( EFKA)-48, EFKA-49 (manufactured by Efka Chemical Co., Ltd.); 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, Ajisper PA111, Ajisper PB811 , Ajisper PW911 (made by Ajinomoto Co., Ltd.); FLOWLEN DOPA-15B, FLOWLEN DOPA-22, FLOWLEN DOPA-17, Floran (FLOWLEN) TG-730W, FLOWLEN G-700, FLOWLEN TG-720W (manufactured by Kyoeisha Chemical Industry Co., Ltd.).

With respect to the polymer dispersant, among these, from the viewpoints of low-temperature sinterability and dispersion stability, the above is preferably Solopers 11200, SOLSPERS 13940, Sonupas (SOLSPERSE) 16000, SONOSPERSE 17000, SOSOLPERSE 18000, SOLSPERSE 28000, DISPERBYK 142, DISPERBYK 174 or DISPERBYK 2155.

The content of the polymer dispersant in the inorganic particle dispersion of the present embodiment is preferably from 0.1% by mass to 15% by mass. When the content of the polymer dispersant is 0.1% by mass or more, the dispersion stability of the obtained inorganic particle dispersion tends to be good, and when it is 15% by mass or less, the conductivity of the inorganic particle dispersion changes. Have a good tendency. A more preferable content of the polymer dispersant is 0.5% by mass to 5% by mass, and a more preferable content is 0.5% by mass to 4% by mass.

(1-4) Dispersion medium The inorganic particle dispersion of the present embodiment contains a dispersion medium in which inorganic particles as a pigment are dispersed. As the dispersion medium, a conventionally known one may be used, but is preferably selected from the group consisting of diethylene glycol dibutyl ether, isotridecyl alcohol, tetrahydronaphthalene, cyclohexylbenzene, terpineol, dihydroterpineol, and Terpene hydroacetate, p-isopropyltoluene, terpene, decane, limonene, isobornyl acetate, saramenol, caryophyllene, terpineyloxyethanol, dihydrofurfuryloxyethanol At least one of the groups.

In the prior art, when the inorganic particles are dispersed in a high-viscosity terpene-based solvent, a hydrocarbon-based solvent (carbon number: 5 to 20) or an aromatic hydrocarbon such as dodecane must be used for dispersion stability. By using these hydrocarbon solvents, only low viscosity inks can be obtained. Further, in order to form the inorganic particle dispersion to have a high viscosity, it is known to increase the concentration of the inorganic particles or to add a thickener. When the concentration of the inorganic particles is increased, the ratio of the solvent is lowered, so that it is difficult to maintain printability or moisture retention. Further, in the method of adding a tackifier, the dispersibility or conductivity of the inorganic particles is lowered. On the other hand, the dispersion medium is used, and the inorganic particles are dispersed by adding a protective dispersant having an acid value, whereby an inorganic particle dispersion having excellent dispersion stability and high viscosity can be obtained.

The content of the dispersion medium in the inorganic particle dispersion of the present embodiment is preferably 10% by mass to 90% by mass. When the content of the dispersion medium is 10% by mass or more, stable dispersibility tends to be obtained, and when it is 90% by mass or less, the film formed of the ink tends to exhibit good conductivity. A more preferable content of the dispersion medium is 20% by mass to 80% by mass, and a more preferable content is 30% by mass to 70% by mass.

In particular, 0.5% by mass to 10% by mass of a fatty acid having a boiling point of 150° C. or higher is added to the dispersion medium in the inorganic particle dispersion of the present embodiment. By including a fatty acid in the dispersion medium, the melting rate (calcination rate) of the inorganic particles (metal particles) can be moderately delayed, and the balance between the volatilization of the organic component and the melting of the metal particles can be obtained, and the strength is stronger and stronger. Bonding layer.

The fatty acid may have at least one carboxyl group, and may have a functional group other than a carboxyl group. The fatty acid is preferably at least one selected from the group consisting of stearic acid, oleic acid, linoleic acid, linoleic acid, and ricinoleic acid. In addition, when the carbon number of the fatty acid is 18 or more, a stronger bonding layer in which the balance between the volatilization of the organic component and the melting of the metal particles is good can be obtained.

(1-5) Protecting Dispersant The inorganic particle dispersion of the present embodiment is characterized by containing a protective dispersant having an acid value added after the synthesis of the inorganic particles (that is, an acid value-protecting agent for dispersing the inorganic particles) Dispersant). Here, the "protective dispersant having an acid value" is any dispersant including an adsorbent group or a functional group which does not have an amine value or a hydroxyl value. By using the protective dispersant, the dispersion stability of the inorganic particles in the solvent can be improved. The protective dispersant has an acid value of from 1 to 200, and preferably the dispersant has a functional group derived from phosphoric acid. The reason for the "protective dispersant having an acid value" is not necessarily clear, but the inventors believe that the adsorption can be carried out in a more dense form not only by adsorption to a metal but also by interaction with a short-chain amine. And has low-temperature sinterability and exhibits high dispersibility.

The reason is that if the acid value of the protective dispersant is 1 or more, the adsorption of the metal substance which coordinates with the amine and becomes alkaline on the surface of the particle starts to be caused by the acid-base interaction, and if it is 200 or less, it does not excessively It has an adsorption point and is therefore adsorbed in a preferred form. In addition, the reason is that by protecting the dispersant from having a functional group derived from phosphoric acid, phosphorus P interacts with the metal M via oxygen O, and thus is most effective for adsorption with a metal or a metal compound, and can be minimized as necessary. The amount of adsorption gives better dispersion.

Further, the amount of the protective dispersant to be added is 0.1% by weight to 10% by weight or less based on the solid content of the inorganic particles. When the content of the protective dispersant is 0.1% or more, the dispersion stability of the obtained inorganic particle dispersion becomes good, but when the content is too large, the low-temperature sinterability is lowered. From such a viewpoint, a more preferable content of the protective dispersant is 0.3% by mass to 10% by mass, and a more preferable content is 0.5% by mass to 8% by mass.

(1-6) Other components In addition to the above-described components, the inorganic particle dispersion of the present embodiment is provided with appropriate viscosity, adhesion, and drying in accordance with the purpose of use, without impairing the effects of the present invention. For example, an oligomer component, a resin component, an organic solvent (which can dissolve or disperse a part of a solid component), a surfactant, or an additive can be added as a binder or a function as a binder. Any component such as adhesive or surface tension modifier. The optional component is not particularly limited.

As the dispersion medium in the optional component, various dispersion media can be used within a range that does not impair the effects of the present invention, and examples thereof include a hydrocarbon or an alcohol.

Examples of the hydrocarbons include aliphatic hydrocarbons, cyclic hydrocarbons, and alicyclic hydrocarbons, and they may be used alone or in combination of two or more. Examples of the aliphatic hydrocarbons include tetradecane, octadecane, heptamethylnonane, tetramethylpentadecane, hexane, heptane, octane, decane, decane, tridecane, and A. A saturated or unsaturated aliphatic hydrocarbon such as a pentane, a normal paraffin or an isoparaffin. Examples of the cyclic hydrocarbon include toluene, xylene, and the like. Further, examples of the alicyclic hydrocarbon include limonene, dipentene, terpinene, terpinene (also known as "terpinene"), nesol (Nesol), pine oil (Cinene), and orange. Perfume, terpinolene, terpinolene (also known as "isoterenene"), water, menthalene, mentorene, tertene, dihydroisopropyltoluene, linalene (Moslene), terpinolene, isodecene (also known as "isoterenene"), γ-terpinene (Crithmene), aut (Kautschin), arylene (Cajeputene), limene (Eulimen) , terpenes, turpentine, menthaline, decane, decene, cyclohexane, and the like.

In addition, the alcohol is a compound containing one or more OH groups in the molecular structure, and examples thereof include an aliphatic alcohol, a cyclic alcohol, and an alicyclic alcohol, and they may be used alone or in combination of two or more. Further, a part of the OH group may be derived from an ethoxy group or the like within a range not impairing the effects of the present invention.

Examples of the aliphatic alcohol include heptanol, octanol (1-octanol, 2-octanol, 3-octanol, etc.), decyl alcohol (1-nonanol, etc.), lauryl alcohol, and tetradecyl alcohol. A saturated or unsaturated C _6-30 aliphatic alcohol such as cetyl alcohol, 2-ethyl-1-hexanol, stearyl alcohol, hexadecenol or oleyl alcohol. Examples of the cyclic alcohol include cresol, eugenol, and the like. Further, examples of the alicyclic alcohol include a cycloalkanol such as cyclohexanol, and terpineol (including an alpha isomer, a beta isomer, a γ isomer, or a mixture of any of these). Terpene alcohol such as hydrogen terpineol (monoterpene alcohol, etc.), dihydroterpineol, myrtenol, sobrerol, menthol, saramenol, perillyl alcohol, rosinol , Sobrerol, verbena, and the like.

Examples of the resin component include a polyester resin, a polyurethane resin such as a blocked isocyanate, a polyacrylate resin, a polypropylene amide resin, a polyether resin, a melamine resin, or a decene. Resin or the like may be used alone or in combination of two or more.

Examples of the organic solvent include, in addition to the above-mentioned dispersion medium, methanol, ethanol, n-propanol, 2-propanol, 1,3-propanediol, 1,2-propanediol, and 1,4-butane. Alcohol, 1,2,6-hexanetriol, 1-ethoxy-2-propanol, 2-butoxyethanol, ethylene glycol, diethylene glycol, triethylene glycol, weight average molecular weight of 200 or more Polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, N,N-dimethylformamide, dimethyl group having a weight average molecular weight of 300 or more and 1,000 or less in a range of 1,000 or less Azulene, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, glycerin or acetone may be used alone or in combination of two or more.

Examples of the tackifier include clay minerals such as clay, bentonite, and hectorite; and emulsions such as a polyester emulsion resin, an acrylic emulsion resin, a polyurethane emulsion resin, or a blocked isocyanate. Cellulose derivatives such as cellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, polysaccharides such as xanthan gum or guar gum; They may be used alone or in combination of two or more.

A surfactant can be added. In the multi-component solvent-based metal colloidal dispersion, roughness of the surface of the film and uneven distribution of solid components are likely to occur due to the difference in volatilization speed during drying. By adding a surfactant to the inorganic particle dispersion of the present embodiment, it is possible to obtain an inorganic particle dispersion which can suppress these disadvantages and form a uniform coating film.

The surfactant which can be used in the present embodiment is not particularly limited, and any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. For example, an alkylbenzenesulfonic acid can be used. Salt, quaternary ammonium salt, and the like. Since the effect can be obtained in a small amount of addition, a fluorine-based surfactant is preferred.

(2) Preparation of the inorganic particle dispersion In order to produce the inorganic particle dispersion of the present embodiment, inorganic particles having a short-chain amine having 6 or less carbon atoms on at least a part of the surface as a main component are adjusted.

In addition, the amount of the "short-chain amine having a carbon number of 6 or less" and the weight reduction rate are not particularly limited, and it is simple to adjust by heating. It can be carried out by adjusting the amount of "alkylamine having 6 or less carbon atoms" added when the inorganic particles are produced. It is also possible to change the cleaning conditions or the number of times the inorganic particles are adjusted. Further, the heating can be carried out by an oven or an evaporator or the like. The heating temperature may be in the range of about 50 to 300 ° C, and the heating time may be from several minutes to several hours. Heating can also be carried out under reduced pressure. The amount of organic matter can be adjusted at a lower temperature by heating under reduced pressure. When it is carried out under normal pressure, it can be carried out in the atmosphere or in an inert environment. Further, in order to finely adjust the amount of the organic component, an amine may be added thereafter.

The method of preparing the inorganic particles coated with the short-chain amine having 6 or less carbon atoms of the present embodiment is not particularly limited, and examples thereof include a method of preparing a dispersion liquid containing inorganic particles, and a method of washing the dispersion liquid. As a step of preparing a dispersion liquid containing inorganic particles, for example, a metal salt (or a metal ion) dissolved in a solvent may be reduced as described below, and the reduction order may be a procedure based on a chemical reduction method. Alternatively, a metal amine complex method can be used.

In other words, the inorganic particles coated with a short-chain amine having 6 or less carbon atoms can be a metal salt containing a metal constituting the inorganic particles, a short-chain amine having 6 or less carbon atoms, the polymer dispersant, and The raw material liquid of the dispersion medium is reduced to prepare. Further, a part of the components of the raw material liquid may be dispersed without being dissolved, and may contain water.

As a starting material for obtaining inorganic particles coated with a short-chain amine having 6 or less carbon atoms, various known metal salts or hydrates thereof can be used, and examples thereof include silver nitrate, silver sulfate, silver chloride, and silver oxide. a silver salt such as silver acetate, silver oxalate, silver formate, silver nitrite, silver chlorate or silver sulfide; for example, a gold salt such as chloroauric acid, potassium gold chloride or gold chloride; for example, chloroplatinic acid, platinum chloride, a platinum salt such as platinum oxide or potassium chloroplatinate; for example, a palladium salt such as palladium nitrate, palladium acetate, palladium chloride, palladium oxide or palladium sulfate; if it is soluble in a suitable dispersion medium and can be reduced, there is no Specially limited. In addition, these may be used alone or in combination.

In addition, the method of reducing these metal salts in the raw material liquid is not particularly limited, and examples thereof include a method of irradiating light such as ultraviolet rays, an electron beam, ultrasonic waves, or thermal energy by a method using a reducing agent. Among them, from the viewpoint of easy handling, a method of using a reducing agent is preferred.

Examples of the reducing agent include amine compounds such as dimethylaminoethanol, methyldiethanolamine, triethanolamine, phenidone, and anthracene; and hydrogen compounds such as sodium borohydride, hydrogen iodide, and hydrogen. For example, oxides such as carbon monoxide and sulfurous acid; for example, ferrous sulfate, iron oxide, ferrous fumarate, iron lactate, iron oxalate, iron sulfide, tin acetate, tin chloride, tin diphosphate, tin oxalate, oxidation a low valence metal salt such as tin or tin sulfate; for example, ethylene glycol, glycerin, formaldehyde, hydroquinone, pyrogallol, tannin, tannic acid, salicylic acid, D-glucose, etc., if It is not particularly limited as long as it can be dissolved in a dispersion medium and the metal salt can be reduced. When the reducing agent is used, light and/or heat may be applied to promote the reduction reaction.

Specific examples of the method of preparing metal particles coated with a short-chain amine having 6 or less carbon atoms using the metal salt, a short-chain amine having 6 or less carbon atoms, a dispersion solvent, and a reducing agent include, for example, the following methods: The metal salt is dissolved in an organic solvent (for example, toluene or the like) to prepare a metal salt solution, and an organic substance as a dispersing agent is added to the metal salt solution, and then a solution in which a reducing agent is dissolved is slowly added dropwise thereto.

In the dispersion liquid containing the metal particles coated with the short-chain amine having a carbon number of 6 or less obtained in the above manner, in addition to the metal particles, a counter ion of the metal salt, a residue of the reducing agent or a dispersing agent, and a solution are present. The overall electrolyte concentration or organic matter concentration tends to be high. The solution in this state causes condensation of metal particles due to high electrical conductivity and is easy to precipitate. Alternatively, if the precipitate is not precipitated, if the counter ion of the metal salt, the residue of the reducing agent, or an excess amount of the dispersant required for the dispersion is left, the conductivity may be deteriorated. Therefore, by washing the solution containing the metal particles to remove excess residue, the metal particles coated with the organic material can be reliably obtained.

As the cleaning method, for example, a method in which the dispersion liquid containing metal particles coated with a short-chain amine having 6 or less carbon atoms is left to stand for a predetermined period of time, and the resulting supernatant is removed. The liquid is then agitated by adding an alcohol (methanol or the like), and then the supernatant is removed after standing for a certain period of time; centrifugation is carried out instead of the method of standing; by means of an ultrafiltration device or an ion exchange device, etc. A method of performing desalination, and the like. By removing such excess residue by such washing and removing the organic solvent, the metal particles coated with the short-chain amine having 6 or less carbon atoms of the present embodiment can be obtained.

Further, as the solvent for cleaning for refining the precipitate, a highly polar solvent such as methanol or water may be used. However, depending on the polarity of the inorganic particles, a solvent having a low polarity may be used. For example, acetone or a mixed solvent of acetone and methanol or the like can be used.

In the present embodiment, the metal colloidal dispersion liquid can be obtained by mixing the obtained metal particles coated with a short-chain amine having 6 or less carbon atoms with the dispersion medium described in the above embodiment. The method of mixing the metal particles coated with the short-chain amine having 6 or less carbon atoms and the dispersion medium is not particularly limited, and it can be carried out by a conventionally known method using a stirrer or a stirrer. It can also be used as a suitable output ultrasonic homogenizer by stirring as a spatula.

When a metal colloidal dispersion liquid containing a plurality of metals is obtained, the method for producing the metal colloidal dispersion is not particularly limited. For example, in the production of a metal colloidal dispersion liquid containing silver and another metal, in the preparation of the metal particles coated with the organic material, The dispersion containing the metal particles and the dispersion containing the other metal particles may be separately produced and then mixed, or the silver ion solution may be mixed with other metal ion solutions and then reduced.

When the metal amine complex method is used, for example, the metal particles may be produced by the following steps: in the first step, an amine mixture containing a short-chain amine having a carbon number of 6 or less and a metal containing a metal atom The compound is mixed to form a miscible compound comprising the metal compound and an amine; and a second step is carried out by heating the miscible compound to form a metal particle.

For example, silver particles protected by an amine protective film can be produced by heating a compound compound formed of a metal compound such as silver oxalate containing silver with an amine in the presence of an amine to cause the miscible compound to be contained. The atomic silver formed by decomposition of a metal compound such as an oxalate ion is aggregated.

Thus, in the metal amine complex decomposition method of producing metal particles coated with an amine by thermally decomposing a compound compound of a metal compound in the presence of an amine, the metal amine is mismatched by a single molecule. Since the atomic metal is formed by the decomposition reaction of the substance, the atomic metal can be uniformly formed in the reaction system, and the composition of the component constituting the reaction can be suppressed from being unstable as compared with the case where the metal atom is formed by the reaction between the various components. The resulting unevenness of the reaction is particularly advantageous when manufacturing a large amount of metal powder on an industrial scale.

It is also presumed that in the metal amine complex decomposition method, an amine molecule is coordinately bonded to the generated metal atom, and the metal atom at the time of coagulation is controlled by the action of an amine molecule coordinated to the metal atom. exercise. As a result, according to the metal amine complex decomposition method, metal particles having a very fine particle size and a narrow particle size distribution can be produced.

Further, a large amount of amine molecules also generate a relatively weak force coordinate bond on the surface of the produced metal fine particles, and these form a dense protective film on the surface of the metal particles, thereby producing a surface cleaning excellent in storage stability. Covered with metal particles. Further, since the amine molecules forming the film can be easily separated by heating or the like, metal particles which can be sintered at a very low temperature can be produced.

In addition, when a solid metal compound and an amine are mixed to form a composite compound such as a compound, a short-chain amine having a carbon number of 6 or less is mixed with a long-chain amine or a medium-chain amine mainly constituting the coating of the metal particle. When used, it is easy to produce a composite compound such as a compound, and a composite compound can be produced in a short time. Further, by using the short-chain amines in combination, it is possible to produce coated metal particles having properties corresponding to various uses.

The inorganic particle dispersion of the present embodiment obtained as described above can be used as a metal bonding composition in the original state, and various inorganic components or various inorganic components can be added without impairing the dispersion stability and low-temperature sinterability of the inorganic particle dispersion. Organic ingredients.

(3) Coating method The inorganic particle dispersion of the present embodiment can be applied by various printing methods. Further, in terms of excellent dispersion stability and moisturizing effect (drying suppressing effect), for example, in inkjet printing, high discharge stability can be exhibited.

When the inorganic particle dispersion of the present embodiment is applied to a substrate, it can be heated and calcined and sintered at a relatively low temperature (for example, 300 ° C or lower, preferably 150 ° C to 250 ° C). A conductive film is obtained. When calcining, the temperature may be raised stepwise or the temperature may be lowered. Further, a surfactant, a surfactant, or the like may be applied in advance to the surface on which the inorganic particle dispersion is applied.

Here, the "coating" of the inorganic particle dispersion of the present embodiment includes the case where the inorganic particle dispersion is applied in a planar shape, and the concept of coating (drawing) into a linear shape is also included. The shape of the coating film containing the inorganic particle dispersion in the state before coating, heating, and calcination can be set as a desired shape. Therefore, the coating film of the inorganic particle dispersion of the present embodiment which is sintered by heating or calcination is a concept including any one of a planar coating film and a linear coating film, and the planar coating film and the linear coating film can be used. Continuous or discontinuous, and may include continuous portions and discontinuous portions.

The base material which can be used in the present embodiment is not particularly limited as long as it can be sintered by heating and calcining the inorganic particle dispersion, and it is preferable to have a temperature which is not damaged by heating or baking. The degree of heat resistance of the component.

Examples of the material constituting such a substrate include polyamide (PA), polyimide (PI), polyamide-imide (PAI), and polyparaphenylene. Polyethylene Terephthalate (PET), Polybutylene Terephthalate (PBT), Polyethylene Naphthalate (PEN), Polyester, Polycarbonate (PC) ), polyether sulfonate (PES), vinyl resin, fluororesin, liquid crystal polymer, ceramic, glass or metal.

Further, the substrate may have various shapes such as a plate shape or a strip shape, and may be rigid or flexible. The thickness of the substrate can also be appropriately selected. In order to improve adhesion or adhesion or other purposes, a member forming a surface layer or a member subjected to surface treatment such as a hydrophilization treatment may be used.

In the step of applying the inorganic particle dispersion to the substrate, various methods can be used, such as self-dipping, screen printing, spray, bar coating, spin coating, ink jet, dispensing, as described above. The apparatus, the needle transfer method, the press method, the coating method by the bristles, the casting type, the flexographic type, the gravure type, the lithography method, the transfer method, the hydrophilic hydrophobic pattern method, or the syringe type are appropriately selected and used.

In the present embodiment, when the inorganic particle dispersion contains the binder component, the binder component is also sintered from the viewpoint of improving the strength of the coating film, etc., but depending on the case, it can be adjusted for application to various printing methods. The viscosity of the inorganic particle dispersion is the main purpose of the binder component, and the calcination conditions are controlled to remove all of the binder components.

The method of performing the heating and the calcination is not particularly limited. For example, the temperature of the inorganic particle dispersion coated or drawn on the substrate is heated or calcined, for example, at 300 ° C or lower, using a conventionally known oven or the like. Thereby, it can be sintered. The lower limit of the temperature of the heating and the calcination is not necessarily limited, and may be a temperature within a range that does not impair the effects of the present invention. Here, in the coating film after the sintering, it is preferable that the residual amount of the organic substance is small in terms of obtaining the highest possible strength, but a part of the organic substance may remain in the range which does not impair the effect of the present invention. .

(4) Joining method When the inorganic particle dispersion of the present embodiment is used, high joint strength can be obtained in joining of members accompanying heating. That is, the first member to be joined and the second member to be joined can be joined by the following steps: a bonding composition coating step of coating the inorganic particle dispersion between the first member to be joined and the second member to be joined In the bonding step, the inorganic particle dispersion coated between the first member to be joined and the second member to be joined is calcined at a desired temperature (for example, 300 ° C or lower, preferably 150 ° C to 250 ° C). Engage.

In the joining step, the first member to be joined and the second member to be joined may also be pressed in the opposite direction, and in particular, sufficient joint strength can be obtained even without pressurization, which is one of the advantages of the present invention. Further, when calcination is carried out, the temperature may be raised stepwise or the temperature may be lowered. Further, a surfactant, a surfactant, or the like may be applied to the surface of the member to be joined in advance.

As a result of intensive research, the present inventors have found that the inorganic particle dispersion in the step of applying the inorganic particle dispersion can use the inorganic particle dispersion of the present embodiment to form the first member to be joined. The second joined member is joined more reliably with a high joint strength (a joined body can be obtained).

Here, the "coating" of the inorganic particle dispersion of the present embodiment includes the case where the inorganic particle dispersion is applied in a planar shape, and the concept of coating (drawing) into a linear shape is also included. The shape of the coating film containing the inorganic particle dispersion in the state before coating and calcination by heating can be set as a desired shape. Therefore, in the joined body of the present embodiment after being fired by heating, the inorganic particle dispersion is a concept including any one of a planar bonding layer and a linear bonding layer, and the planar bonding layer and the linear bonding layer It may be continuous or discontinuous, and may also include continuous portions and discontinuous portions.

The first member to be joined and the second member to be joined which can be used in the present embodiment are not particularly limited as long as they can be joined by firing by heating the inorganic particle dispersion, and it is preferably provided. A member having heat resistance that is not damaged by the temperature at the time of joining.

Examples of the material constituting such a member to be joined include polyacrylamide (PA), polyimine (PI), polyamidimide (PAI), and polyethylene terephthalate (PET). Polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyester, polycarbonate (PC), polyether oxime (PES), vinyl resin, fluororesin, liquid crystal polymerization A material, a ceramic, a glass or a metal, etc., among which a metal bonded member is preferable. The metal bonded member is preferably excellent in heat resistance and excellent in affinity with the inorganic particle dispersion of the present invention containing metal particles as a main component.

Further, the member to be joined may have various shapes such as a plate shape or a strip shape, and may be rigid or flexible. The thickness of the substrate can also be appropriately selected. In order to improve adhesion or adhesion or other purposes, a member forming a surface layer or a member subjected to surface treatment such as a hydrophilization treatment may be used.

In the step of applying the inorganic particle dispersion to the member to be joined, various methods can be used, as described above, for example, self-dipping, screen printing, spray, bar coating, spin coating, ink jet, Dispensing type, needle transfer method, stamping method, coating method by bristles, casting type, flexographic type, gravure type, lithography method, transfer method, hydrophilic hydrophobic pattern method, or syringe type, etc. .

The coating film coated as described above is calcined by, for example, heating to a temperature of 300 ° C or lower within a range where the bonded member is not damaged, and a joined body can be obtained. In the present embodiment, the inorganic particle dispersion of the present embodiment is used as described above, whereby a bonding layer having excellent adhesion to the member to be joined can be obtained, and strong bonding strength can be obtained more reliably.

In the present embodiment, when the inorganic particle dispersion contains the binder component, the binder component is also sintered from the viewpoint of improving the strength of the bonding layer and improving the bonding strength between the members to be joined, and depending on the case, In order to apply to various printing methods, the viscosity of the inorganic particle dispersion is adjusted as a main purpose of the binder component, and the calcination conditions are controlled to remove all of the binder components.

The method of performing the calcination is not particularly limited, and for example, it can be calcined by using a conventionally known oven or the like so that the temperature of the inorganic particle dispersion coated or drawn on the member to be joined is, for example, 300 ° C or lower. This is joined. The lower limit of the temperature of the calcination is not necessarily limited, and is preferably a temperature at which the members to be joined are joined to each other at a temperature that does not impair the effects of the present invention. Here, in the inorganic particle dispersion after the calcination, the amount of residual organic matter is preferably small in terms of obtaining the highest possible bonding strength, but the organic substance is not impaired in the range of the effect of the present invention. Some of them can also survive.

Further, the inorganic particle dispersion of the present invention contains an organic substance, and unlike the prior art, such as an epoxy resin, which is thermally cured, the joint strength after firing is not obtained by the action of the organic substance, but is as described above. The bonding of the molten metal particles gives a sufficient joint strength. Therefore, even after the bonding, the organic substance remaining in the use environment having a high temperature higher than the bonding temperature does not deteriorate or decompose or disappear, and the joint strength is not lowered, so that the heat resistance is excellent.

According to the inorganic particle dispersion of the present embodiment, it is possible to achieve bonding of the bonding layer which exhibits high conductivity by firing at a low temperature of, for example, about 150 ° C to 250 ° C. Therefore, it is possible to bond the bonding layer which is relatively weak in heat. The members are joined to each other. Further, the calcination time is not particularly limited, and the calcination temperature may be a calcination time that can be joined.

In order to further improve the adhesion between the member to be joined and the bonding layer, surface treatment of the member to be joined may be performed. Examples of the surface treatment method include a method of performing dry treatment such as corona treatment, plasma treatment, ultraviolet (UV) treatment, or electron beam treatment, and an undercoat layer or a conductive paste is previously provided on a substrate. The method of receiving the layer, etc.

Although the representative embodiments of the present invention have been described above, the present invention is not limited thereto. For example, in the above-described embodiment, a metal colloidal dispersion liquid using metal particles as inorganic particles has been described, but tin-doped indium oxide excellent in conductivity, thermal conductivity, dielectric properties, ion conductivity, and the like may be used. Inorganic particles such as alumina, barium titanate, and lithium iron phosphate.

Hereinafter, in the examples, the inorganic particle dispersion of the present invention will be further described, but the present invention is not limited to these examples. [Examples]

≪Example 1≫ butylamine (a reagent manufactured by Wako Pure Chemical Industries Co., Ltd.), carbon number: 4, logP: 1.0) 0.9 g, hexylamine (a reagent manufactured by Wako Pure Chemical Industries, Ltd.), carbon Number: 6, logP: 2.1) 2.5 g and 0.3 g of DISPARBYK-174 (manufactured by BYK Chemical Co., Ltd.) as a polymer dispersant, and stirred by a magnetic stirrer to form an amine mixture. liquid. Next, 3.0 g of silver oxalate was added while stirring. After the addition of silver oxalate, stirring was continued at room temperature, whereby silver oxalate was changed to a viscous white substance, and the stirring was terminated at the point when the change was considered to be finished (first step).

The resulting mixture was transferred to an oil bath and heated and stirred at 120 °C. The reaction accompanying the generation of carbon dioxide is started immediately after the stirring, and thereafter, the stirring is performed until the generation of carbon dioxide is completed, whereby a suspension in which the silver fine particles are suspended in the amine mixture is obtained (second step). Next, in order to replace the dispersion medium of the suspension, 10 mL of methanol was added and stirred, and silver fine particles were precipitated by centrifugation to separate, and 10 mL of methanol was added to the separated silver fine particles, and the mixture was stirred and centrifuged. In this way, silver fine particles were precipitated and separated, and dispersed in a polymer dispersant SOSOLERS 16000 (manufactured by Lubrizol Corporation) of 0.03 g (1.5% by weight based on the solid content of silver). The alcohol C was 2.4 g and mixed, thereby obtaining silver fine particle dispersion 1.

[Evaluation Test] (1) Dispersibility The silver fine particle dispersion 1 obtained as described above was allowed to stand in a container, and after standing at room temperature for 1 day, the presence or absence of the precipitate and the supernatant were visually observed. The dispersibility of the silver colloidal dispersion 1 was evaluated in the state of the liquid. The case where the precipitate was hardly found under the container was evaluated as "○", and the case where a small amount of precipitate was found was evaluated as "△", and the difference in concentration was observed in the upper and lower sides of the container, and the condition of the precipitate was clearly found as " ×". The results are shown in Table 1. Here, the room temperature was 25 °C.

(2) Dilution The dispersibility when the silver fine particle dispersion 1 obtained as described above was diluted 100 times in a dispersion medium was visually evaluated. The case where the dispersion was performed was evaluated as "○", and the case where a part of the particles were aggregated or visible was evaluated as "△", and the case where aggregation or precipitation occurred was evaluated as "X". The results are shown in Table 1.

(3) Viscosity measurement The viscosity of the silver fine particle dispersion 1 obtained as described above was measured using a cone-and-plate type viscometer (rheometer manufactured by Anton Paar Co., Ltd., MCR301). The measurement conditions were the measurement mode: shear mode, shear rate: 10 s ^-1 , measurement jig: cone and plate (CP-50-2; diameter 50 mm, angle 2°, gap 0.045 mm), measurement temperature: 25 °C. The results are shown in Table 1.

(4) Volume resistance value The silver fine particle dispersion 1 obtained in the above manner was applied to a glass slide to form a coating film in a gear oven at 150 ° C, 30 minutes or 200 ° C for 30 minutes. The film is sintered by heating and calcination to form a conductive film. The volume resistivity of the film was measured using a DC precision measuring device "Portable Double Bridge 2769" manufactured by Yokohama & Instruments (INSTRUMENTS). Specifically, the volume resistance value is converted from the distance between the measurement terminals and the thickness of the conductive film according to the following formula. The case where the volume resistance value was 20 μΩ·cm or less was evaluated as “○”, and the case where the volume resistance value was more than 20 μΩ·cm was evaluated as “×”. The results are shown in Table 1. Formula: (volume resistance value ρv) = (resistance value R) × (film width w) × (film thickness t) / (inter-terminal distance L)

(5) Measurement of organic component The content of the organic component contained in the silver fine particle dispersion 1 obtained as described above was measured by a thermogravimetric analysis. Specifically, the solid content of the silver fine particle dispersion 1 is heated at a temperature increase rate of 10 ° C / min, and the content of the organic component is determined by the weight loss of room temperature to 200 ° C and 200 ° C to 500 ° C. The results are shown in Table 1. Here, the room temperature was 25 °C.

Example 2 A silver fine particle dispersion 2 was obtained in the same manner as in Example 2 except that dihydroterpineol was used instead of the terpene dihydroacetate. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

≪Example 3≫ Using methoxyamine (a reagent manufactured by Wako Pure Chemical Industries Co., Ltd., carbon number: 4, logP: -1.5) 0.9 g instead of butylamine (Wako Pure Chemical Industries, Ltd.) Silver fine particle dispersion 3 was obtained in the same manner as in Example 2 except that the reagent was produced in the first stage, carbon number: 4, and log P: 1.0) 0.9 g. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

≪Example 4≫ A terpine-based oxyethanol (Terusolve TOE-100: Japan Terpene Chemical Co., Ltd.) was used instead of dihydroterpineol, and Example 3 was used. Silver fine particle dispersion 4 was obtained in the same manner. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

≪Example 5≫ Polymer dispersant to be added to terpine-based oxyethanol (Terusolve TOE-100: Japan Terpene Chemical Co., Ltd.) by SONOSPERSE 16000 Silver microparticle dispersion 5 was obtained in the same manner as in Example 4 except that BYK-P104 (manufactured by BYK Chemical Co., Ltd.), 0.06 g (1.5% by weight based on the silver solid content) was used as the active ingredient of 50%. . The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

≪Example 6≫ In place of terpine-based oxyethanol (Terusolve TOE-100: Japan Terpene Chemical Co., Ltd.), dihydrofurfuryloxyethanol was used, in addition to The silver fine particle dispersion 6 was obtained in the same manner as in Example 4. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

≪Example 7≫ The amount of the polymer dispersant SONOSPERS 16000 added to the dihydrofurfuryloxyethanol was changed from 0.03 g to 0.015 g (0.75 wt% with respect to the silver solid content) Except for this, the silver fine particle dispersion 7 was obtained in the same manner as in Example 6. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

≪Example 8≫ The polymer dispersant added to the dihydroterpineol was changed to SONOSPERSE 18000, and the addition amount was set to 0.03 g (1.5% by weight based on the silver solid content) Except for this, the obtained silver fine particle dispersion 8 was obtained in the same manner as in Example 2. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

Example 9 A mixture of 0.9 g of butylamine, 2.5 g of hexylamine, and 0.3 g of SONOSPERSE as a polymer dispersant was thoroughly stirred by a magnetic stirrer to form an amine mixed solution. Next, 3.0 g of silver oxalate was added while stirring. After the addition of silver oxalate, stirring was continued at room temperature, whereby silver oxalate was changed to a viscous white substance, and the stirring was terminated at the point when the change was considered to be finished (first step).

The resulting mixture was transferred to an oil bath and heated and stirred at 120 °C. The reaction accompanying the generation of carbon dioxide is started immediately after the stirring, and thereafter, the stirring is performed until the generation of carbon dioxide is completed, whereby a suspension in which the silver fine particles are suspended in the amine mixture is obtained (second step). Next, in order to replace the dispersion medium of the suspension, 10 mL of a mixed solvent of methanol/acetone (ratio 4:1) is added and stirred, and silver fine particles are precipitated by centrifugation to separate, and the separated silver fine particles are again separated. 10 mL of a mixed solvent of methanol/acetone (ratio 4:1) was added, and the mixture was stirred and centrifuged, whereby silver fine particles were precipitated and separated to be dispersed in 0.002 g (0.1% by weight relative to the solid content of silver). The polymer dispersant SONOSPERS was added in an amount of 16,000 to 2.4 g of dihydrofurfuryloxyethanol and mixed to obtain a silver fine particle dispersion 9. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

≪Example 10≫ Put 0.3 g of SONOSPERSE 16000 in place of DISPERBYK-174, and use dihydroterpineol instead of terpineol C, in addition to The obtained silver fine particle dispersion 10 was obtained in the same manner as in Example 1. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 1.

Comparative Example 1 A comparative silver fine particle dispersion 1 was obtained in the same manner as in Example 1 except that the polymer dispersant was not added to the terpineol C of the dispersion medium. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 2≫ Comparative silver particle dispersion 2 was obtained in the same manner as in Comparative Example 1, except that 0.3 g of SONOSPERSE 16000 was placed in place of DISPERBYK-174. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 3 比较 Comparative silver particle dispersion 3 was obtained in the same manner as in Comparative Example 1, except that terpineol C was used instead of the dispersion medium. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 4≫ No butylamine (a reagent manufactured by Wako Pure Chemical Industries Co., Ltd., carbon number: 4, logP: 1.0) 0.9 g, and hexylamine (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) Comparative silver particle dispersion 4 was obtained in the same manner as in Comparative Example 2 except that carbon number: 6, log P: 2.1) 2.5 g. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 5≫ In place of the dihydroterpineol of the dispersion medium, a terpene-based oxyethanol (Terusolve TOE-100: Nippon Terpene Chemical Co., Ltd.) was used. Comparative Example 2 obtained comparative silver particle dispersion 5 in the same manner. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 6≫ In addition to terpine-based oxyethanol (Terusolve TOE-100: Japan Terpene Chemical Co., Ltd.) using dihydrofurfuryloxyethanol instead of the dispersion medium, Comparative silver particle dispersion 6 was obtained in the same manner as in Comparative Example 2. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 7≫ The polymer dispersing agent added to the dihydroterpineol was changed to SONOSPERSE 11200, and the amount added was set to 0.03 g (1.5% by weight based on the silver solid content) Except for this, the obtained comparative silver fine particle dispersion 7 was obtained in the same manner as in Example 10. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 8 设为 The polymer dispersing agent to be added to the dihydroterpineol was set to 0.06 g (1.5% by weight based on the silver solid content) BYK-P105 (manufactured by BYK Chemical Co., Ltd.), and Comparative silver particle dispersion 8 was obtained in the same manner as in Example 8. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 9 量 The amount of the polymer dispersant SONOSPERS 16000 added to the dihydrofurfuryloxyethanol was changed from 0.03 g to 0.001 g (0.05% by weight relative to the silver solid content) Except for this, Comparative Silver Particles Dispersion 9 was obtained in the same manner as in Example 9. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

≪Comparative Example 10 索 A mixture of 0.9 g of butylamine, 2.5 g of hexylamine, and 0.4 g of SONOSPERSE as a polymer dispersant was thoroughly stirred by a magnetic stirrer to form an amine mixed solution. Next, 3.0 g of silver oxalate was added while stirring. After the addition of silver oxalate, stirring was continued at room temperature, whereby silver oxalate was changed to a viscous white substance, and the stirring was terminated at the point when the change was considered to be finished (first step).

The resulting mixture was transferred to an oil bath and heated and stirred at 120 °C. The reaction accompanying the generation of carbon dioxide is started immediately after the stirring, and thereafter, the stirring is performed until the generation of carbon dioxide is completed, whereby a suspension in which the silver fine particles are suspended in the amine mixture is obtained (second step). Next, in order to replace the dispersion medium of the suspension, 10 mL of methanol was added and stirred, and silver fine particles were precipitated by centrifugation to separate, and 10 mL of methanol was again added to the separated silver fine particles, and stirred and centrifuged. Thereby, silver fine particles were precipitated and separated to obtain a comparative silver fine particle dispersion 10 which was dispersed in 2.4 g of dihydrofurfuryloxyethanol.

≪Comparative Example 11 量 The amount of the polymer dispersant SONOSPERS 16000 added to the dihydrofurfuryloxyethanol was changed from 0.03 g to 0.3 g (15% by weight relative to the silver solid content) Except for this, Comparative Silver Particles Dispersion 11 was obtained in the same manner as in Example 6. The same evaluation test as in Example 1 was carried out, and the results are shown in Table 2.

[Table 1] Table 1

[Table 2] Table 2

According to the results shown in Table 2, as in the examples, the inorganic particle dispersion (silver fine particle dispersion) of the present invention is a silver fine particle dispersion (silver fine particle dispersion) which has a low viscosity diterpene dihydroacetate as a solvent. Other than 10), it has a high viscosity of 15 mPa·s or more at 25 °C. In addition, it has excellent dispersibility and dilution. Further, it is understood that a good (sufficiently low) volume resistance value is exhibited, and an inorganic particle dispersion which is excellent in dispersion stability and high viscosity and which can be calcined at a relatively low temperature can be obtained.

On the other hand, when the protective dispersant was not added later (comparative inorganic particle dispersion 1 to comparative inorganic particle dispersion 3), sufficient dispersibility and dilutability were not obtained. Further, in the comparative silver fine particle dispersion 4 in which the short-chain amine having 6 or less carbon atoms was not added, silver particles could not be obtained.

When terpene ether type (terpine-based oxyethanol, dihydrofurfuryloxyethanol) is used as a dispersion medium without adding a protective dispersant (comparison of silver fine particle dispersion 5 and comparative silver fine particle dispersion) 6) A dispersion of inorganic particles in which silver fine particles are dispersed cannot be obtained. On the other hand, after the silver fine particles are synthesized, a protective dispersing agent is added, whereby the dispersibility of the silver fine particles for the terpene ether-based (terpine-based oxyethanol, dihydrofurfuryloxyethanol) is remarkably improved (silver fine particles) Dispersion 4 to silver fine particle dispersion 7 and silver fine particle dispersion 9).

From the comparison of the silver fine particle dispersion 6, the silver fine particle dispersion 7, the silver fine particle dispersion 9, and the comparative silver fine particle dispersion 11, it is understood that the amount of the protective dispersant added affects the conductivity and the dispersibility. Specifically, when the amount of addition is too large, the dispersibility is good but not turned on, and when the amount added is too small, the volume resistivity is lowered, but the dispersibility is deteriorated.

Further, in the case where the protective dispersant did not have an acid value (compared to the silver fine particle dispersion 7) and the acid value was too high (compared with the silver fine particle dispersion 8), sufficient dispersibility was not obtained.

Further, according to the silver fine particle dispersion 9, it was found that the dispersibility was improved by optimizing the cleaning solvent.

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Claims (8)

An inorganic particle dispersion comprising: inorganic particles having a short-chain amine having a carbon number of 6 or less on at least a part of a surface; and a polymer dispersant comprising a pigment affinity group in a main chain and/or a plurality of side chains And a polymer having a comb structure constituting a plurality of side chains of a solvation portion, a polymer having a plurality of pigment affinity portions containing a pigment affinity group in the main chain, or a pigment affinity at a single end of the main chain a linear polymer having a pigment-affinity moiety; and a dispersion medium comprising a protective dispersant having an acid value in the dispersion medium, wherein the protective dispersant has an acid value of from 1 to 200, and the protection The amount of the dispersant added is 0.1% by weight to 10% by weight or less based on the solid content of the inorganic particles. The inorganic particle dispersion according to claim 1, wherein the short-chain amine comprises an alkylamine and/or an alkoxyamine. The inorganic particle dispersion according to claim 1 or 2, wherein the short-chain amine is selected from the group consisting of butylamine, pentylamine, hexylamine, 2-methoxyethylamine, 2- At least one of the group consisting of ethoxyethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, and 4-methoxybutylamine. The inorganic particle dispersion according to any one of claims 1 to 3, wherein the content of the dispersion medium is from 1% by mass to 90% by mass. The inorganic particle dispersion according to any one of claims 1 to 4, wherein the dispersion medium is selected from the group consisting of diethylene glycol dibutyl ether, isotridecyl alcohol, tetrahydronaphthalene, and cyclohexyl. Benzene, terpineol, dihydroterpineol, terpene dihydroacetate, p-isopropyl toluene, terpene, decane, limonene, isobornyl acetate, saramenol, caryophyllene, terpenoid oxygen At least one selected from the group consisting of ethanol and dihydrofurfuryloxyethanol. The inorganic particle dispersion according to any one of claims 1 to 5, wherein a weight reduction rate when heated from room temperature to 200 ° C by thermal analysis is 5% or less, and heating from 200 ° C The weight reduction rate up to 500 ° C is 10% or less. The inorganic particle dispersion according to any one of claims 1 to 6, wherein the dispersion medium contains 0.5% by mass to 10% by mass of a fatty acid having a boiling point of 150 ° C or higher. The inorganic particle dispersion according to any one of claims 1 to 7, wherein the fatty acid is selected from the group consisting of stearic acid, oleic acid, linoleic acid, linoleic acid, and ricinoleic acid. At least one of the group consisting of.