JP6290402B2 - Inorganic particle dispersion - Google Patents

Description

  The present invention relates to an inorganic particle dispersion containing metal particles, and more specifically, has excellent dispersion stability, and is suitable for joining metal parts at relatively low temperatures, wiring of electronic materials, and electrodes. The present invention relates to an inorganic particle dispersion that can be used for the above.

  Conventionally, it has been known that metal nanoparticles (or metal colloid particles) having a large specific surface area and high reaction activity have a property of being fused (low temperature sintering) at a lower temperature than bulk or metal atoms. Taking advantage of the properties, for example, inorganic particle dispersion (conductive paste) is expected to be applied to various fields. Here, in order to expand the application range of the inorganic particle dispersion to various printing methods, it is very important to adjust the viscosity of the inorganic particle dispersion.

  For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2009-097074) and the like, metal colloid particles composed of metal nanoparticles (A) and protective colloid (B) covering the metal nanoparticles (A), And a paste containing the dispersion medium of the metal colloidal particles, wherein the protective colloid (B) is composed of amines (B1) and a carboxylic acid (B2) having 4 or more carbon atoms. , Has been proposed.

  In the metal nanoparticle paste of Patent Document 1, the protective colloid covering the metal nanoparticles is not an organic binder (resin binder) but a specific compound that easily evaporates or decomposes at a low temperature and also acts as a binder. Therefore, the sintered pattern can be formed at a low temperature even by a screen printing method for forming a relatively thick film or an intaglio printing method.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-150543) is an ink composition containing silver nanoparticles, a hydrocarbon solvent, and an alcohol cosolvent, and the hydrocarbon solvent contains at least five hydrocarbon solvents. An aliphatic hydrocarbon having 20 to 20 carbon atoms or an aromatic hydrocarbon having 7 to 18 carbon atoms, and the alcohol cosolvent is mostly α-terpineol by weight. Ink compositions that are certain terpineol solvents have been proposed.

  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 a line as low as 60 μm is obtained due to improved ink stability and uniform printing characteristics. In addition to being able to achieve width, it is said that it can be jetted onto various substrate surfaces with different surface energies to obtain printing characteristics.

JP 2009-097074 A JP 2010-150543 A

  However, in the metal nanoparticle paste described in Patent Document 1, the dispersion stability of the metal nanoparticles is not sufficiently ensured. In the ink composition described in Patent Document 2, it is essential to use a hydrocarbon solvent (carbon number 5 to 20) such as dodecane or an aromatic hydrocarbon for dispersion stability. With the use of these hydrocarbon solvents, only low viscosity inks can be realized.

  Conventionally, as a technique for increasing the viscosity of an ink composition containing metal nanoparticles, it has been known to increase the concentration of the metal nanoparticles or to add a thickener. The ratio decreases, and the printability and moisture retention cannot be ensured. On the other hand, when a thickener is added, the dispersibility of the metal nanoparticles and the conductivity of the ink composition are reduced.

  In view of the circumstances as described above, an object of the present invention is to provide an inorganic particle dispersion that has excellent dispersion stability in a wide viscosity range (particularly a high viscosity range) and can be fired at a relatively low temperature. It is in.

  Here, in general, ink for inkjet or reverse offset printing is adjusted in a low viscosity range of 5 to 15 mPa · s. That is, when the viscosity is 15 mPa · s or more, it can be said that the ink used in the printing technique has a high viscosity.

  As a result of intensive studies on the composition and dispersant of the inorganic particle dispersion to achieve the above object, the present inventor has selected an appropriate solvent and added a dispersant having an acid value. The inventors have found that it is effective and have reached the present invention.

That is, the present invention
Inorganic particles having a short-chain amine having 6 or less carbon atoms on at least a part of the surface;
A polymer having a comb-like structure having a pigment affinity group in the main chain and / or a plurality of side chains and having a plurality of side chains constituting a solvation part, a plurality of pigment affinity groups in the main chain A polymer dispersant containing a polymer having a pigment affinity part, or a linear polymer having a pigment affinity part composed of a pigment affinity group at one end of the main chain;
A dispersion medium,
A polymer protective dispersant having an acid value in the dispersion medium,
The acid value of the protective dispersant is 1 to 200,
The addition amount of the protective dispersant is 0.1 to 10% by weight or less based on the solid content of the inorganic particles,
The dispersion medium is a terpene material;
The viscosity is 15 mPa · s or more,
Obtained by adding the protective dispersant to the inorganic particles after the production of the inorganic particles,
An inorganic particle dispersion is provided.

  Here, in the inorganic particle dispersion of the present invention, the short chain amine is preferably composed of alkylamine and / or alkoxyamine, and includes butylamine, pentylamine, hexylamine, 2-methoxyethylamine, 2-ethoxyethylamine, More preferably, it is at least one selected from the group consisting of 3-methoxypropylamine, 3-ethoxypropylamine, and 4-methoxybutylamine.

  The inorganic particle dispersion of the present invention having the above-described configuration can be sintered at a low temperature because it contains a low molecular weight amine, that is, has excellent low temperature sinterability, and has excellent dispersibility because it contains a polymer dispersant. Long-term dispersion stability. In addition, by using a component that contributes to low-temperature sinterability (mainly an alkylamine having 6 or less carbon atoms) and a component that contributes to dispersion stability (mainly a polymer dispersant), both components are adsorbed on the surface of the inorganic particles. , Express each property. In addition, since dispersion stability can be ensured by including a polymer dispersant as described above, various physical property preparation agents can be added for general-purpose printing suitability.

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

  The polymer dispersant has a graft structure in which a pigment-affinity group is present in the side chain and has a side chain constituting a solvation part (the following comb-shaped polymer (1)); Since it has a pigment affinity group (the following polymer (copolymer) (2) and the above linear polymer (3)), the dispersibility of colloidal particles composed of inorganic particles is good, and inorganic Suitable as protective colloid for particles. By using the polymer dispersant, an inorganic particle dispersion (conductive ink and conductive paste) composed of an inorganic particle dispersion containing inorganic particles at a high concentration can be obtained.

  Furthermore, the inorganic particle dispersion of the present invention includes a protective dispersant having an acid value added after the synthesis of the inorganic particles (that is, a protective dispersant having an acid value for dispersing the inorganic particles). . The “protective dispersant having an acid value” here includes all dispersants having no amine value or hydroxyl value as an adsorbing group or a functional group. By using such a protective dispersant, the dispersion stability of the inorganic particles in the solvent can be improved. The acid value of the protective dispersant is 1 to 200, and the dispersant preferably has a functional group derived from phosphoric acid. The reason why the “protective dispersant having an acid value” is preferable is not necessarily clear, but the present inventors have not only adsorbed the metal but also interacted with a short-chain amine in a denser form. It can be adsorbed and is considered to exhibit high dispersibility while having low-temperature sinterability.

If the acid value of the protective dispersant is 1 or more, adsorption by an acid-base interaction starts to occur on a metal substance coordinated with an amine and the particle surface is basic. This is because it is adsorbed in a suitable form because it does not have any. In addition, since the protective dispersant has a functional group derived from phosphoric acid, phosphorus P interacts with and attracts the metal M through the oxygen O, so it is most effective for adsorption to metals and metal compounds, and is the minimum necessary. It is because suitable dispersibility can be obtained with the adsorbing amount. Here, the “acid value” is expressed in mg of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample. Examples of the acid value measurement method include an indicator method (p-naphtholbenzein indicator) and a potentiometric titration method.
ISO6618-1997: Neutralization titration method by indicator titration method → Corresponding to indicator titration method (acid value) ISO6619-1988: Corresponding to potentiometric titration method (acid value) → Potentiometric titration method (acid value)

  Moreover, the addition amount of the said protective dispersant is 0.1 to 10 weight% or less with respect to solid content of the said inorganic particle. If the content of the protective dispersant is 0.1% or more, the dispersion stability of the resulting inorganic particle dispersion is improved. However, if the content is too large, the low-temperature sinterability is lowered. From such a viewpoint, the more preferable content of the protective dispersant is 0.3 to 10% by mass, and the more preferable content is 0.5 to 8% by mass.

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

  Moreover, in the inorganic particle dispersion of the present invention, the dispersion medium is diethylene glycol dibutyl ether, isotridecanol, tetralin, cyclohexylbenzene, terpineol, dihydroterpineol, dihydroterpinyl acetate, p-cymene, pinene, pinane, It is preferably at least one selected from the group consisting of limonene, isobornyl acetate, carveol, caryophyllene, terpinyloxyethanol, dihydroterpinyloxyethanol.

  The dispersion of this embodiment further has a weight reduction rate of 5% or less when heated from room temperature to 200 ° C. by thermal analysis, and a weight reduction rate of 10% when heated from 200 ° C. to 500 ° C. The following is preferable. Here, the weight reduction rate up to 200 ° C. mainly indicates the content of the short-chain amine, which is a low-temperature component contributing to low-temperature sinterability, and the weight reduction rate of the high-temperature property at 200 to 500 ° C. is mainly dispersion stability. The content of the dispersant having an acid value that contributes to If the short-chain amine or the high temperature component is excessive, the low temperature sintering property is impaired. That is, if the weight reduction rate when heated from room temperature to 200 ° C. is 5% or less and the weight reduction rate when heated from 200 ° C. to 500 ° C. is 10% or less, the low temperature sinterability is more excellent.

  Furthermore, in the inorganic particle dispersion of the present invention, it is preferable that the dispersion medium contains 0.5 to 10% by mass of a fatty acid having a boiling point of 150 ° C. or higher. The fatty acid is stearic acid, oleic acid, linoleic acid, More preferably, it is at least one selected from the group consisting of linolenic acid and ricinoleic acid. By containing fatty acids in the dispersion medium, the fusion rate (firing rate) of inorganic particles (metal particles) can be moderately delayed, and the balance between volatilization of organic components and fusion of metal particles is improved. Thus, a stronger bonding layer can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, while having the outstanding dispersion stability and high viscosity, the inorganic particle dispersion which can be baked at a comparatively low temperature can be provided.

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

The inorganic particle dispersion of this embodiment is
Inorganic particles having a short-chain amine having 6 or less carbon atoms on at least a part of the surface;
A polymer having a comb-like structure having a pigment affinity group in the main chain and / or a plurality of side chains and having a plurality of side chains constituting a solvation part, a plurality of pigment affinity groups in the main chain A polymer dispersant containing a polymer having a pigment affinity part, or a linear polymer having a pigment affinity part composed of a pigment affinity group at one end of the main chain;
A dispersion medium,
A polymer protective dispersant having an acid value in the dispersion medium,
The acid value of the protective dispersant is 1 to 200,
The addition amount of the protective dispersant is 0.1 to 10% by weight or less based on the solid content of the inorganic particles,
The dispersion medium is a terpene material;
The viscosity is 15 mPa · s or more,
Obtained by adding the protective dispersant to the inorganic particles after the production of the inorganic particles,
It is characterized by.

  As described above, the inorganic particle dispersion is added not only to the synthesis of the inorganic particles, but also to a dispersion medium having an acid value added to a dispersion medium having a viscosity (particularly a high viscosity dispersion medium) in which the inorganic particles are to be dispersed. As a result, the dispersibility of the inorganic particles is remarkably improved. It also has good low temperature sintering.

  In order to increase the viscosity of the inorganic particle dispersion to a high viscosity (15 mPa · s or more), it is preferable to use a terpene-based material or the like which is a high viscosity / high boiling point solvent as a dispersion medium. However, since inorganic particles dispersed in an organic solvent tend to destabilize the functional groups (OH groups, etc.) of the terpene material, it is difficult to use the terpene material alone or as a main solvent.

  On the other hand, in the inorganic particle dispersion of the present embodiment, various investigations are 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. While maintaining the above, the dispersibility of the inorganic particles is drastically improved. Here, even if a protective dispersant having no acid value is used, the dispersibility is not improved, and if the acid value is too high, the same effect cannot be obtained.

  It is considered that the protective dispersant having an acid value can be adsorbed in a denser form by interacting with the short-chain amine as well as adsorbing to the inorganic particles, and exhibits high dispersibility. The reason why the dispersibility of the polymer dispersant having an acid value in the terpene-based material (dispersion medium) is not necessarily clear, but the protective dispersant can be added to the inorganic particles by adding the protective dispersant after the addition. It is not adsorbed on and floats in the solvent. Here, the floating protective dispersant has a large inhibitory effect on the aggregation of inorganic particles in the high-viscosity dispersion medium that is a terpene-based material, and is caused by a large contribution to the dispersion stability of the inorganic particles. Conceivable. In the case where the protective dispersant is not added later, since the protective dispersant other than the protective dispersant adsorbed on the inorganic particles is removed by the washing operation during the precipitation purification, there is basically no floating protective dispersant.

  The protective dispersant is preferably added to the dispersion medium in advance, but may be added after the inorganic particles are dispersed in the dispersion medium. The method for adding the protective dispersant to the dispersion medium is not particularly limited, and may be added by various conventionally known methods.

  The inorganic particle dispersion of the present embodiment has a weight reduction rate of 5% by mass or less when heated from room temperature to 200 ° C. by thermal analysis, and a weight reduction rate of 10% when heated from 200 ° C. to 500 ° C. It is preferable that it is below mass%. Here, the weight reduction rate up to 200 ° C. mainly indicates the content of low temperature components (mainly short chain amines having 6 or less carbon atoms) that contribute to low temperature sintering, and the weight reduction rate at 200 to 500 ° C. is mainly dispersed. The content of the high temperature component (mainly polymer dispersant) that contributes to stability is shown.

  When the low temperature component is excessive, the dispersion stability is impaired, and when the high temperature component is excessive, the low temperature sinterability is impaired. That is, if the weight reduction rate when heated from room temperature to 200 ° C. is 5% by mass or less, the dispersion stability is more excellent, and if the weight reduction rate when heated from 200 ° C. to 500 ° C. is 10% by mass or less. Low temperature sinterability is better.

  The inorganic particle dispersion of the present embodiment includes, as a main component, metal colloid particles in which inorganic particles (metal particles) described later are colloided. Regarding the form of the metal colloid particles, for example, the surface of the metal particles Metal colloidal particles composed of organic materials attached to a part of them, metal colloidal particles composed of the above metal particles as a core, and the surface of which is coated with organic materials, and a metal composed of them mixed Although colloidal particles etc. are mentioned, it is not specifically limited. Among these, metal colloidal particles having a metal particle as a core and a surface coated with an organic substance are preferable. A person skilled in the art can appropriately prepare the metal colloid particles having the above-described form using a well-known technique in this field.

  The inorganic particle dispersion of the present embodiment is a fluid mainly composed of colloidal particles composed of metal particles and organic matter. In addition to metal particles and organic matter constituting metal colloidal particles, metal colloidal particles are constituted. May contain an organic substance, a dispersion medium, a residual reducing agent, or the like.

  Examples of the method for applying the inorganic particle dispersion of the present embodiment on the substrate include dipping, screen printing, spray method, bar coating method, spin coating method, ink jet method, dispenser method, pin transfer method, stamping method, It can be appropriately selected from a brush application method, a casting method, a flexo method, a gravure method, an offset method, a transfer method, a hydrophilic / hydrophobic pattern method, or a syringe method.

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

  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, bismuth, tin, iron, and platinum. And at least one of group elements (ruthenium, rhodium, palladium, osmium, iridium and platinum). The metal is preferably particles of at least one metal selected from the group consisting of gold, silver, copper, nickel, bismuth, tin, or platinum group elements, and more preferably has a tendency to ionize than copper or copper. Is preferably a small (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. The methods for using these metals in combination include the case of using alloy particles containing a plurality of metals, the metal having a core-shell structure or a multilayer structure. Particles may be 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 issues are considered. Thus, migration can be made difficult to occur by using an inorganic particle dispersion made of silver and other metals. The “other metal” is preferably a metal in which the ionization column is more noble than hydrogen, that is, gold, copper, platinum, or palladium.

  The average particle diameter of the metal particles (or metal colloid particles) in the inorganic particle dispersion of the present embodiment is not particularly limited as long as the effect of the present invention is not impaired, but a melting point drop occurs. It is preferable to have an average particle diameter, for example, it may be 1 to 200 nm. Furthermore, it is preferable that it is 2-100 nm. If the average particle diameter of the metal particles is 1 nm or more, an inorganic particle dispersion capable of forming a good coating film can be obtained, and the production of metal particles is practical without increasing the cost. Moreover, if it is 200 nm or less, the dispersibility of a metal particle hardly changes with time, and it is preferable.

  If necessary, micrometer-sized metal particles can be added in combination. In such a case, a favorable conductive path can be obtained by the melting point drop of the nanometer-sized metal particles around the micrometer-sized metal particles.

  In particular, the present inventor uses a metal particle having a small particle diameter that exhibits a melting point drop as described above, and an inorganic particle dispersion containing an amine adhering to at least a part of the surface of the metal particle has a specific temperature range. It was found that by optimizing the weight reduction rate during heating in a specific range, the low-temperature sinterability and dispersion stability are improved in a balanced manner as compared with inorganic particle dispersions that are not.

  Note that the particle size of the metal particles in the inorganic particle dispersion of the present embodiment may not be constant. In addition, when the inorganic particle dispersion includes a dispersion medium, a resin component, a thickener, a surface tension adjuster, or the like, which will be described later, as an optional component, it may include a metal colloid particle component having an average particle size of more than 200 nm. As long as the component does not cause aggregation and does not significantly impair the effects of the present invention, a particle component having an average particle diameter of more than 200 nm may be included.

Here, the particle size 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, and a wide angle X-ray diffraction method. In order to show the melting point drop of the nano-sized metal particles, the crystallite diameter determined by the wide-angle X-ray diffraction method is appropriate. For example, in the wide-angle X-ray diffraction method, more specifically, Rθ-UtimaIII manufactured by Rigaku Corporation can be used to measure 2θ in the range of 30 to 80 ° by the diffraction method. In this case, the sample may be measured by extending it thinly so that the surface is flat on a glass plate having a depression of about 0.1 to 1 mm in depth at the center. The crystallite diameter (D) calculated by substituting the half width of the obtained diffraction spectrum into the following Scherrer equation using JADE manufactured by Rigaku Corporation may be used as the particle diameter.
D = Kλ / Bcos θ
Here, K: Scherrer constant (0.9), λ: wavelength of X-ray, B: half width of diffraction line, θ: Bragg angle.

(1-2) Short-chain amine having 6 or less carbon atoms In the inorganic particle dispersion according to this 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. In addition, on the surface of the inorganic particles, like a trace amount organic substance contained as an impurity from the beginning of the raw material, a trace amount organic substance mixed in the manufacturing process described later, a residual reducing agent that could not be removed in the cleaning process, a residual dispersant, etc. A trace amount of organic matter may be attached.

  The short-chain amine is not particularly limited as long as it has 6 or less carbon atoms. The short-chain amine may be linear or branched, and may have a side chain. Or an alkoxyamine, preferably selected from the group consisting of butylamine, pentylamine, hexylamine, 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, 4-methoxybutylamine. More preferably, it is at least one kind.

  The short chain amine may be 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. Moreover, the said amine may be used independently, respectively and may use 2 or more types together. In addition, the boiling point at normal pressure is preferably 300 ° C. or lower, more preferably 250 ° C. or lower.

  The inorganic particle dispersion of the present embodiment may contain a carboxylic acid in addition to the short-chain amine having 6 or less carbon atoms as long as the effects of the present invention are not impaired. The carboxyl group in one molecule of the carboxylic acid has a relatively high polarity and tends to cause an interaction due to a hydrogen bond, but a portion other than these functional groups has a relatively low polarity. Furthermore, the carboxyl group tends to exhibit acidic properties. In addition, when the carboxylic acid is localized (attached) to at least a part of the surface of the inorganic particle (that is, covers at least a part of the surface of the inorganic particle) in the inorganic particle dispersion of this embodiment, the solvent And the inorganic particles can be sufficiently made to adhere to each other, and aggregation between the inorganic particles can be prevented (dispersibility is improved).

  As the carboxylic acid, compounds having at least one carboxyl group can be widely used, and examples thereof include formic acid, oxalic acid, acetic acid, hexanoic acid, acrylic acid, octylic acid, and oleic acid. A part of carboxyl groups of the carboxylic acid may form a salt with a metal ion. In addition, about the said metal ion, 2 or more types of metal ions may be contained.

  The carboxylic acid may be 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 mercapto group. In this case, the number of carboxyl groups is preferably equal to or greater than the number of functional groups other than carboxyl groups. Moreover, the said carboxylic acid may be used independently, respectively and may use 2 or more types together. In addition, the boiling point at normal pressure is preferably 300 ° C. or lower, more preferably 250 ° C. or lower. Also, amines and carboxylic acids form amides. Since the amide group is also adsorbed moderately on the surface of the inorganic particles, the amide group may be attached to the surface of the inorganic particles.

  When the colloid is composed of inorganic particles and organic substances (such as the short-chain amine having 6 or less carbon atoms) attached to the surface of the inorganic particles, the content of the organic component in the colloid is 0.5 to 50. It is preferable that it is mass%. If the organic component content is 0.5% by mass or more, the storage stability of the obtained inorganic particle dispersion tends to be improved, and if it is 50% by mass or less, the inorganic particle dispersion is obtained by heating. There exists a tendency for the electroconductivity of a sintered body to be good. The more preferable content of the organic component is 1 to 30% by mass, and the more preferable content is 2 to 15% by mass.

(1-3) Polymer Dispersant The polymer dispersant contained in the inorganic particle dispersion of the present embodiment has a graft structure in which a pigment affinity group is present in a side chain and a side chain that constitutes a solvation part. Those having a pigment affinity group in the main chain (the following polymer (copolymer) (2) and the above-mentioned linear polymer (3)). . For this reason, the dispersibility of colloidal particles made of inorganic particles is good, and it is suitable as a protective colloid for inorganic particles. By using the polymer dispersant, an inorganic particle dispersion composed of an inorganic particle dispersion containing inorganic particles at a high concentration can be obtained.

  Here, with respect to the polymer dispersant, the pigment affinity group refers to a functional group having a strong adsorptive power to the surface of a pigment made of inorganic particles, such as a tertiary amino group or a quaternary ammonium group. And a heterocyclic group having a basic nitrogen atom, a hydroxyl group, a carboxyl group, and the like. In the present invention, the pigment affinity group exhibits a strong affinity for metal particles. The high molecular weight pigment dispersant can exhibit sufficient performance as a protective colloid of metal particles by having the pigment affinity group.

  The comb-shaped polymer (1) has a structure in which a plurality of side chains constituting a solvation portion are bonded to a main chain together with a plurality of side chains having the pigment affinity group. It is connected to the main chain like a comb tooth. In the present specification, the above structure is referred to as a comb structure. In the comb-shaped polymer (1), the pigment affinity group may be present not only at the end of the side chain but also in the middle of the side chain or in the main chain. In addition, the said solvation part is a part which has affinity to a solvent, Comprising: A hydrophilic or hydrophobic structure is said. The solvation part is composed of, for example, a water-soluble polymer chain, a lipophilic polymer chain, and the like.

The comb-shaped polymer (1) is not particularly limited, and has, for example, one or more poly (carbonyl-C ₃ -C ₆ -alkyleneoxy) chains disclosed in JP-A-5-177123. Each of these chains has ₃ to 80 carbonyl-C ₃ -C ₆ -alkyleneoxy groups and is bonded to poly (ethyleneimine) by an amide or salt bridging group. Or a salt thereof; comprising a reaction product of a poly (lower alkylene) imine disclosed in JP-A-54-37082 and a polyester having a free carboxylic acid group, and each poly (lower alkylene) ) At least two polyester chains bonded to an imine chain; a high molecular weight compound having an epoxy group at the end as disclosed in JP-B-7-24746 The epoxy compound, and pigment dispersing agent obtained by reacting a carboxyl group-containing prepolymer of the amine compound having a number average molecular weight from 300 to 7000 concurrently or in any order.

  The comb-shaped polymer (1) is preferably one having 2 to 3000 pigment affinity groups in one molecule. If it is less than 2, the dispersion stability is not sufficient, and if it exceeds 3000, the viscosity is too high and handling becomes difficult, and the particle size distribution of the colloidal particles made of metal particles becomes unnecessarily wide. Stability may be reduced. More preferably, it is 25 to 1500.

  The comb-shaped polymer (1) is preferably one in which 2 to 1000 side chains constituting the solvation portion are present in one molecule. If it is less than 2, the dispersion stability is not sufficient, and if it exceeds 1000, the viscosity is too high and handling becomes difficult, and the particle size distribution of the colloidal particles made of metal particles becomes wider than necessary, and the dispersion stability. May decrease. More preferably, it is 5-500.

  The comb-shaped polymer (1) preferably has a number average molecular weight of 2,000 to 1,000,000. If it is less than 2,000, the dispersion stability is not sufficient, and if it exceeds 1,000,000, the viscosity is too high and handling becomes difficult, and the particle size distribution of the colloidal particles made of metal particles becomes wider than necessary, and the dispersion stability. May decrease. More preferably, it is 4000-500000.

  The polymer (copolymer) (2) having a plurality of pigment-affinity moieties consisting of pigment-affinity groups in the main chain is one in which a plurality of pigment-affinity groups are arranged along the main chain, The pigment affinity group is, for example, pendant to the main chain. In the present specification, the pigment-affinity part refers to a part that has one or more pigment-affinity groups and functions as an anchor that adsorbs to the pigment surface made of inorganic particles.

  Examples of the copolymer (2) include a polyisocyanate disclosed in JP-A-4-210220, a mixture of a monohydroxy compound and a monohydroxymonocarboxylic acid or monoaminomonocarboxylic acid compound, and at least Reaction product of one basic ring nitrogen and a compound having an isocyanate reactive group; disclosed in JP-A-60-16631, JP-A-2-612, and JP-A-63-24410 A polymer in which a plurality of tertiary amino groups or groups having a basic cyclic nitrogen atom are pendant on a main chain made of polyurethane / polyurea; a water-soluble poly (oxyalkylene) disclosed in JP-A-1-279919 A copolymer comprising a steric stabilizing unit having a chain, a structural unit and an amino group-containing unit, and containing an amine group A unit containing a tertiary amino group or a group of an acid addition salt thereof or a quaternary ammonium group, and containing 0.025 to 0.5 milliequivalent amino group per gram of the copolymer. A polymer; a main chain composed of an addition polymer disclosed in JP-A-6-1000064, and a stabilizer unit composed of at least one C1-C4 alkoxy polyethylene or polyethylene-copropylene glycol (meth) acrylate; An amphiphilic copolymer having a weight average molecular weight of 2500 to 20000, the main chain comprising up to 30% by weight of non-functional structural units and a total of up to 70% by weight of stabilizer Units and functional units, the functional units being substituted or unsubstituted styrene-containing units, hydroxyl group-containing units and carboxylic acids. The ratio of hydroxyl group and carboxyl group, hydroxyl group and styrene group, and hydroxyl group and propyleneoxy group or ethyleneoxy group is 1: 0.10 to 26.1; 1: 0. Examples include amphiphilic polymers such as 28 to 25.0; 1: 0.80 to 66.1.

  The copolymer (2) preferably has 2 to 3000 pigment-affinity groups in one molecule. If it is less than 2, the dispersion stability is not sufficient, and if it exceeds 3000, the viscosity is too high and handling becomes difficult, and the particle size distribution of the colloidal particles made of inorganic particles becomes wider than necessary. Stability may be reduced. More preferably, it is 25 to 1500.

  The copolymer (2) preferably has a number average molecular weight of 2000 to 1000000. If it is less than 2000, the dispersion stability is not sufficient, and if it exceeds 1000000, the viscosity is too high and handling becomes difficult, and the particle size distribution of the colloidal particles made of inorganic particles becomes wider than necessary, and the dispersion stability. May decrease. More preferably, it is 4000-500000.

  The linear polymer (3) having a pigment affinity portion composed of a pigment affinity group at one end of the main chain is a pigment affinity portion composed of one or more pigment affinity groups only at one end of the main chain. Have sufficient affinity for the pigment surface.

  The linear polymer (3) is not particularly limited, and for example, an AB block type polymer, one of which is basic disclosed in JP-A-46-7294; US Pat. No. 4,656,226 AB block type polymer in which an aromatic carboxylic acid is introduced into the A block disclosed in the specification of U.S. Pat. No. 4,032,698, one end of which is a basic functional group Block type polymer: AB block type polymer having one end of an acidic functional group disclosed in US Pat. No. 4,070,388; US Pat. No. 4,656,226 disclosed in JP-A-1-204914 What improved the weather yellowing of AB block type polymer which introduce | transduced aromatic carboxylic acid into A block as described in a specification etc. can be mentioned.

  The linear polymer (3) is preferably one having 2 to 3000 pigment affinity groups in one molecule. If it is less than 2, the dispersion stability is not sufficient, and if it exceeds 3000, the viscosity is too high and handling becomes difficult, and the particle size distribution of the colloidal particles made of inorganic particles becomes wider than necessary. Stability may be reduced. More preferably, it is 5 to 1500.

  The linear polymer (3) preferably has a number average molecular weight of 1,000 to 1,000,000. If it is less than 1000, the dispersion stability is not sufficient, and if it exceeds 1000000, the viscosity is too high and handling becomes difficult, and the particle size distribution of the colloidal particles made of inorganic particles becomes wider than necessary, and the dispersion stability. May decrease. More preferably, it is 2000-500000.

  As the polymer dispersant, commercially available ones can also be used. Examples of the commercially available products include Solsperse 11200, Solsperse 13940, Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 20000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000 (manufactured by Nippon Lubrizol Co., Ltd .; Disperse) DISPERBYK 102; Dispersic 110, Dispersic 111, Dispersic 142, Dispersic 160, Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 166, Dispersic 170, Dispersic 174, Dispersic 180, Dispersic 182 184, Dispersic 190, Dispersic 2155, BYK-P104, BYK-P105 (manufactured by BYK Chemie Japan); EFKA-46, EFKA-47, EFKA-48, EFKA-49 (manufactured by EFKA Chemical); 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); Azisper PB711, Azisper PA111, Azisper PB811, Azisper PW911 ( Ajinomoto Co., Inc.); Florene DOPA-15B, Florene DOPA-22, Florene DOPA-17, Floren TG-730W, Floren G-700, Floren TG-720 And W (manufactured by Kyoeisha Chemical Industry Co., Ltd.).

  Among these, the polymer dispersant may be Solsperse 11200, Solsperse 13940, Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 28000, Dispersic 142, Dispersic 174 or Dispersic 2155 at a low temperature. It is preferable from the viewpoints of sinterability and dispersion stability.

  The content of the polymer dispersant in the inorganic particle dispersion of the present embodiment is preferably 0.1 to 15% by mass. If the content of the polymer dispersant is 0.1% by mass or more, the dispersion stability of the resulting inorganic particle dispersion tends to be improved. If the content is 15% by mass or less, the conductivity of the inorganic particle dispersion is likely to be improved. Tend to be better. The more preferable content of the polymer dispersant is 0.5 to 5% by mass, and the more preferable content is 0.5 to 4% by mass.

(1-4) Dispersion medium The inorganic particle dispersion of the present embodiment includes a dispersion medium that disperses inorganic particles that are pigments. As the dispersion medium, conventionally known ones can be used, but diethylene glycol dibutyl ether, isotridecanol, tetralin, cyclohexylbenzene, terpineol, dihydroterpineol, dihydroterpinyl acetate, p-cymene, pinene, pinane, It is preferably at least one selected from the group consisting of limonene, isobornyl acetate, carveol, caryophyllene, terpinyloxyethanol, dihydroterpinyloxyethanol.

  In the conventional technology, when inorganic particles are dispersed in a high-viscosity terpene solvent, a hydrocarbon solvent (carbon number 5 to 20) such as dodecane or an aromatic hydrocarbon may be used in combination for dispersion stability. Since these hydrocarbon solvents are used, only low viscosity inks can be obtained. In order to increase the viscosity of the inorganic particle dispersion, it is known to increase the concentration of inorganic particles or to add a thickener. However, if the concentration of inorganic particles is increased, Since the ratio decreases, it is difficult to maintain printability and moisture retention. Moreover, in the method of adding a thickener, the dispersibility and conductivity of the inorganic particles are lowered. On the other hand, an inorganic particle dispersion having both excellent dispersion stability and high viscosity can be obtained by dispersing inorganic particles with the addition of a protective dispersant having an acid value using the dispersion medium. .

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

  It is preferable that 0.5 to 10% by mass of a fatty acid having a boiling point of 150 ° C. or higher is further added to the dispersion medium in the inorganic particle dispersion of the present embodiment. By containing fatty acids in the dispersion medium, the fusion rate (firing rate) of inorganic particles (metal particles) can be moderately delayed, and the balance between volatilization of organic components and fusion of metal particles is improved. Thus, a stronger bonding layer can be obtained.

  The said fatty acid should just have at least one carboxyl group, and may have functional groups 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, linolenic acid and ricinoleic acid. Further, if the fatty acid has 18 or more carbon atoms, the balance between the volatilization of the organic component and the fusion of the metal particles is improved, and a stronger bonding layer can be obtained.

(1-5) Protective dispersant The inorganic particle dispersion of the present embodiment is a protective dispersant having an acid value added after synthesis of inorganic particles (that is, a protective dispersant having an acid value for dispersing inorganic particles). It is characterized by including. The “protective dispersant having an acid value” here includes all dispersants having no amine value or hydroxyl value as an adsorbing group or a functional group. By using such a protective dispersant, the dispersion stability of the inorganic particles in the solvent can be improved. The acid value of the protective dispersant is 1 to 200, and the dispersant preferably has a functional group derived from phosphoric acid. The reason why the “protective dispersant having an acid value” is preferable is not necessarily clear, but the present inventors have not only adsorbed the metal but also interacted with a short-chain amine in a denser form. It can be adsorbed and is considered to exhibit high dispersibility while having low-temperature sinterability.

  If the acid value of the protective dispersant is 1 or more, adsorption by an acid-base interaction starts to occur on a metal substance coordinated with an amine and the particle surface is basic. This is because it is adsorbed in a suitable form because it does not have any. In addition, since the protective dispersant has a functional group derived from phosphoric acid, phosphorus P interacts with and attracts the metal M through the oxygen O, so it is most effective for adsorption to metals and metal compounds, and is the minimum necessary. It is because suitable dispersibility can be obtained with the adsorbing amount.

  Moreover, the addition amount of the said protective dispersant is 0.1 to 10 weight% or less with respect to solid content of the said inorganic particle. If the content of the protective dispersant is 0.1% or more, the dispersion stability of the resulting inorganic particle dispersion is improved. However, if the content is too large, the low-temperature sinterability is lowered. From such a viewpoint, the more preferable content of the protective dispersant is 0.3 to 10% by mass, and the more preferable content is 0.5 to 8% by mass.

(1-6) Other components In addition to the above-described components, the inorganic particle dispersion of the present embodiment has an appropriate viscosity, adhesion, and drying properties in accordance with the intended use within a range that does not impair the effects of the present invention. Alternatively, in order to impart functions such as printability, a dispersion medium, an oligomer component that serves as a binder, for example, a resin component, an organic solvent (a part of the solid content may be dissolved or dispersed), a surface activity. You may add arbitrary components, such as an agent, a thickener, or a surface tension modifier. Such optional components are not particularly limited.

  As the dispersion medium of the optional components, various types can be used as long as the effects of the present invention are not impaired, and examples thereof include hydrocarbons and alcohols.

  Examples of the hydrocarbon include aliphatic hydrocarbons, cyclic hydrocarbons and alicyclic hydrocarbons, and each may be used alone or in combination of two or more. Examples of the aliphatic hydrocarbon include saturated or unsaturated aliphatic hydrocarbons such as tetradecane, octadecane, heptamethylnonane, tetramethylpentadecane, hexane, heptane, octane, nonane, decane, tridecane, methylpentane, normal paraffin, and isoparaffin. Is mentioned. Examples of the cyclic hydrocarbon include toluene and xylene. Further, examples of the alicyclic hydrocarbon include limonene, dipentene, terpinene, terpinene (also referred to as terpinene), nesol, sinene, orange flavor, terpinolene, terpinolene (also referred to as terpinolene), ferrandylene, mentadiene, teleben, Examples thereof include dihydrocymene, moslen, isoterpinene, isoterpinene (also referred to as isoterpinene), clitomen, kautssin, cajeptene, oilimene, pinene, turpentine, menthane, pinane, terpene, and cyclohexane.

  Alcohol is a compound containing one or more OH groups in the molecular structure, and examples thereof include aliphatic alcohols, cyclic alcohols and alicyclic alcohols, and each may be used alone or in combination of two or more. Also good. Moreover, a part of OH group may be induced | guided | derived to the acetoxy group etc. in the range which does not impair the effect of this invention.

Examples of the aliphatic alcohol include heptanol, octanol (1-octanol, 2-octanol, 3-octanol, etc.), decanol (1-decanol, etc.), lauryl alcohol, tetradecyl alcohol, cetyl alcohol, 2-ethyl-1- Examples thereof include saturated or unsaturated C _6-30 aliphatic alcohols such as hexanol, octadecyl alcohol, hexadecenol and oleyl alcohol. Examples of the cyclic alcohol include cresol and eugenol. Further, as the alicyclic alcohol, for example, cycloalkanol such as cyclohexanol, terpineol (including α, β, γ isomers, or any mixture thereof), terpene alcohol such as dihydroterpineol (monoterpene alcohol etc. ), Dihydroterpineol, myrtenol, sobrerol, menthol, carveol, perillyl alcohol, pinocarveol, sobrerol, berbenol and the like.

  Examples of the resin component include polyester resins, polyurethane resins such as blocked isocyanate, polyacrylate resins, polyacrylamide resins, polyether resins, melamine resins, and terpene resins. May be used alone or in combination of two or more.

  As the organic solvent, except for those mentioned as the above dispersion medium, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, 2-propyl alcohol, 1,3-propanediol, 1,2-propanediol, 1 , 4-butanediol, 1,2,6-hexanetriol, 1-ethoxy-2-propanol, 2-butoxyethanol, ethylene glycol, diethylene glycol, triethylene glycol, weight average molecular weight in the range of 200 to 1,000 Polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol having a weight average molecular weight in the range of 300 to 1,000, N, N-dimethylformamide, dimethyl sulfoxide, N- Chill-2-pyrrolidone, N, N- dimethylacetamide, glycerin, or acetone and the like may be used each of which alone or in combination of two or more.

  Examples of the thickener include clay minerals such as clay, bentonite or hectorite, for example, emulsions such as polyester emulsion resins, acrylic emulsion resins, polyurethane emulsion resins or blocked isocyanates, methyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose. , Cellulose derivatives such as hydroxypropylcellulose and hydroxypropylmethylcellulose, polysaccharides such as xanthan gum and guar gum, and the like. These may be used alone or in combination of two or more.

  A surfactant may be added. In a multi-component solvent-based metal colloidal dispersion, roughness of the coating surface and uneven solid content are likely to occur due to differences in volatilization rate during drying. By adding a surfactant to the inorganic particle dispersion of the present embodiment, these disadvantages are suppressed, and an inorganic particle dispersion that can form a uniform coating film is obtained.

  The surfactant that 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 alkylbenzene sulfonate. A quaternary ammonium salt etc. are mentioned. Since the effect can be obtained with a small addition amount, a fluorosurfactant is preferable.

(2) Preparation of 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 prepared. .

  The adjustment of the amount of “short-chain amine having 6 or less carbon atoms” and the weight reduction rate are not particularly limited, but it is easy to adjust by heating. You may carry out by adjusting the quantity of the "C6 or less alkylamine" added when producing an inorganic particle. You may change the washing | cleaning conditions and frequency | counts after inorganic particle adjustment. Heating can be performed with an oven, 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 several minutes to several hours. Heating may be performed under reduced pressure. By heating under reduced pressure, the amount of organic matter can be adjusted at a lower temperature. When performed under normal pressure, it can be performed in air or in an inert atmosphere. In addition, amines can be added later for fine adjustment of the organic content.

  A method for preparing inorganic particles coated with a short-chain amine having 6 or less carbon atoms according to the present embodiment is not particularly limited. For example, a dispersion containing inorganic particles is prepared, and then the dispersion is washed. The method of performing etc. are mentioned. As a step of preparing a dispersion containing inorganic particles, for example, a metal salt (or metal ion) dissolved in a solvent may be reduced as described below, and the reduction procedure is based on a chemical reduction method. A procedure may be adopted. Moreover, a metal amine complex method can also be used.

  That is, the inorganic particles coated with the short-chain amine having 6 or less carbon atoms as described above, the metal salt of the metal constituting the inorganic particles, the short-chain amine having 6 or less carbon atoms, the polymer dispersant, It can prepare by reducing the raw material liquid containing the said dispersion medium. In addition, a part of component of the raw material liquid may be dispersed without dissolving, and water may be contained.

  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. For example, silver nitrate, silver sulfate, silver chloride, Silver salts such as silver oxide, silver acetate, silver oxalate, silver formate, silver nitrite, silver chlorate and silver sulfide; for example, gold salts such as chloroauric acid, potassium gold chloride and sodium gold chloride; for example, chloroplatinic acid Platinum salts such as platinum chloride, platinum oxide and potassium chloroplatinate; for example, palladium salts such as palladium nitrate, palladium acetate, palladium chloride, palladium oxide, palladium sulfate, etc., but are dissolved in a suitable dispersion medium. It is not particularly limited as long as it can be obtained and reduced. These may be used alone or in combination.

  The method for reducing these metal salts in the raw material liquid is not particularly limited, and examples thereof include a method using a reducing agent, a method of irradiating light such as ultraviolet rays, electron beams, ultrasonic waves, or thermal energy. Among these, a method using a reducing agent is preferable from the viewpoint of easy operation.

  Examples of the reducing agent include amine compounds such as dimethylaminoethanol, methyldiethanolamine, triethanolamine, phenidone, and hydrazine; for example, hydrogen compounds such as sodium borohydride, hydrogen iodide, and hydrogen gas; for example, carbon monoxide. Oxides such as sulfurous acid; for example, ferrous sulfate, iron oxide, iron fumarate, iron lactate, iron oxalate, iron sulfide, tin acetate, tin chloride, tin diphosphate, tin oxalate, tin oxide, sulfuric acid Low valent metal salts such as tin; for example, sugars such as ethylene glycol, glycerin, formaldehyde, hydroquinone, pyrogallol, tannin, tannic acid, salicylic acid, D-glucose, etc. There is no particular limitation as long as it can be reduced. When the reducing agent is used, light and / or heat may be added to promote the reduction reaction.

  As a specific method for 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, for example, the above metal A method in which a salt is dissolved in an organic solvent (for example, toluene) to prepare a metal salt solution, an organic substance as a dispersant is added to the metal salt solution, and then a solution in which the reducing agent is dissolved is gradually added dropwise. Is mentioned.

  In the dispersion liquid containing the metal particles coated with the short-chain amine having 6 or less carbon atoms obtained as described above, in addition to the metal particles, a metal salt counterion, a reducing agent residue and a dispersing agent are contained. It exists and tends to have a high electrolyte concentration and organic matter concentration in the entire liquid. Since the liquid in such a state has high conductivity, the metal particles are likely to coagulate and precipitate easily. Alternatively, even if precipitation does not occur, the conductivity of the metal salt may deteriorate if the counter ion of the metal salt, the residue of the reducing agent, or an excessive amount of dispersant remaining in the amount necessary for dispersion remains. Therefore, by washing the solution containing the metal particles to remove excess residues, the metal particles coated with an organic substance can be reliably obtained.

  As the washing method, for example, a dispersion containing metal particles coated with a short-chain amine having 6 or less carbon atoms is allowed to stand for a certain period of time, and the resulting supernatant is removed, and then alcohol (methanol or the like) is added. The method of repeating the process of removing the supernatant liquid after standing again for a certain period of time and removing the supernatant is repeated several times, the method of centrifuging instead of the above-mentioned standing, the ultrafiltration device, the ion exchange device, etc. Examples include a salting method. By removing excess residues and removing the organic solvent by such washing, the metal particles coated with the short-chain amine having 6 or less carbon atoms according to the present embodiment can be obtained.

  In addition, as a washing solvent for purifying the precipitate, a highly polar solvent such as methanol or water is often used, but a solvent having a lower polarity can be used in accordance with the polarity of the inorganic particles. For example, acetone or a mixed solvent of acetone and methanol can be used.

  Among the embodiments, the metal colloid dispersion is obtained by mixing the metal particles coated with the short-chain amine having 6 or less carbon atoms obtained above and the dispersion medium described in the embodiment. . The method for 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 can be performed by a conventionally known method using a stirrer or a stirrer. An ultrasonic homogenizer with an appropriate output may be applied by stirring with a spatula or the like.

  When obtaining a metal colloid dispersion liquid containing a plurality of metals, the production method is not particularly limited. For example, when producing a metal colloid dispersion liquid composed of silver and other metals, the metal colloid dispersion liquid is coated with the above organic substance. In the preparation of metallic particles, a dispersion containing metal particles and a dispersion containing other metal particles may be produced separately and then mixed, or a silver ion solution and other metal ion solution may be mixed. Thereafter, reduction may be performed.

  When the metal amine complex method is used, for example, an amine mixed solution containing a short-chain amine having 6 or less carbon atoms and a metal compound containing a metal atom are mixed, and the complex compound containing the metal compound and the amine is mixed. What is necessary is just to manufacture a metal particle by the 1st process which produces | generates, and the 2nd process which decomposes | disassembles and produces | generates a metal particle by heating the said complex compound.

  For example, atoms generated by decomposing a metal compound such as oxalate ion contained in the complex compound by heating a complex compound formed from a metal compound such as silver oxalate containing silver and an amine in the presence of the amine Silver particles protected by an amine protective film can be produced by aggregating the silver particles.

  Thus, in the metal amine complex decomposition method for producing metal particles coated with amine by thermally decomposing a complex compound of a metal compound in the presence of amine, decomposition of the metal amine complex which is a single kind of molecule is performed. Since the atomic metal is generated by the reaction, it is possible to generate the atomic metal uniformly in the reaction system, and the reaction is configured as compared with the case where the metal atom is generated by the reaction between multiple components. Inhomogeneity of the reaction due to fluctuations in the composition of the components is suppressed, which is particularly advantageous when a large amount of metal powder is produced on an industrial scale.

  In the metal amine complex decomposition method, an amine molecule is coordinated to the metal atom to be generated, and the movement of the metal atom during aggregation is controlled by the action of the amine molecule coordinated to the metal atom. Inferred. As a result, according to the metal amine complex decomposition method, it is possible to produce metal particles that are very fine and have a narrow particle size distribution.

  Furthermore, a large number of amine molecules also form a relatively weak coordination bond on the surface of the metal fine particles to be produced, and these form a dense protective film on the surface of the metal particles, so that the storage stability is excellent. It becomes possible to produce coated metal particles having a clean surface. In addition, since the amine molecules forming the film can be easily desorbed by heating or the like, metal particles that can be sintered at a very low temperature can be produced.

  In addition, when a solid metal compound and an amine are mixed to produce a complex compound such as a complex compound, the number of carbon atoms is 6 or less with respect to the long-chain / medium-chain amine that mainly constitutes the coating of the coated metal particles. By mixing and using a short-chain amine, it is easy to produce a complex compound such as a complex compound, and the complex compound can be produced by mixing in a short time. In addition, by using a mixture of the short-chain amines, coated metal particles having characteristics according to various uses can be produced.

  The inorganic particle dispersion of this embodiment obtained as described above can be used as it is as a metal bonding composition, but does not impair the dispersion stability and low-temperature sinterability of the inorganic particle dispersion. Various inorganic components and organic components can be added within a range.

(3) Coating method The inorganic particle dispersion of this embodiment can be coated using various printing methods. Moreover, since it has the outstanding dispersion stability and the moisture retention effect (drying suppression effect), high discharge stability can be exhibited at the time of inkjet printing, for example.

  If the inorganic particle dispersion of this embodiment is used, after applying to a substrate, it is heated and fired at a relatively low temperature (for example, 300 ° C. or less, preferably 150 to 250 ° C.) and sintered to obtain a conductive film. be able to. When firing, the temperature can be raised or lowered stepwise. Moreover, it is also possible to apply | coat a surfactant or surface active agent etc. previously to the surface which apply | coats an inorganic particle dispersion.

  Here, “application” of the inorganic particle dispersion of the present embodiment is a concept including both cases where the inorganic particle dispersion is applied in a planar form and applied (drawn) in a linear form. The shape of the coating film made of the inorganic particle dispersion before being applied and heated and baked can be made into a desired shape. Therefore, the coating film of the inorganic particle dispersion of the present embodiment sintered by heating / firing is a concept including both a planar coating film and a linear coating film. The coating film may be continuous or discontinuous, and may include a continuous part and a discontinuous part.

  The substrate that can be used in the present embodiment is not particularly limited as long as it can be applied with an inorganic particle dispersion, heated, fired, and sintered. The temperature at the time of heating and firing is not particularly limited. It is preferable that the member has a heat resistance sufficient to prevent damage.

  Examples of the material constituting such a base material include polyamide (PA), polyimide (PI), polyamideimide (PAI), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and the like. Polyester, polycarbonate (PC), polyethersulfone (PES), vinyl resin, fluororesin, liquid crystal polymer, ceramics, glass or metal can be used.

  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 selected as appropriate. In order to improve adhesion or adhesion, or for other purposes, a member on which a surface layer is formed or a member subjected to a surface treatment such as a hydrophilic treatment may be used.

  In the step of applying the inorganic particle dispersion to the substrate, various methods can be used. As described above, for example, dipping, screen printing, spraying, bar coating, spin coating, ink jet , Dispenser method, pin transfer method, stamping method, brush coating method, casting method, flexo method, gravure method, offset method, transfer method, hydrophilic / hydrophobic pattern method, syringe method, etc. Can do.

  In the present embodiment, when the inorganic particle dispersion includes a binder component, the binder component is also sintered from the viewpoint of improving the strength of the coating film, etc., but in some cases, for application to various printing methods. The main purpose of the binder component is to adjust the viscosity of the inorganic particle dispersion, and the binder component may be completely removed by controlling the firing conditions.

  The method for performing the heating and baking is not particularly limited. For example, the temperature of the inorganic particle dispersion applied or drawn on the substrate using a conventionally known oven or the like is, for example, 300 ° C. or less. It can be sintered by heating and baking. The lower limit of the heating / firing temperature is not necessarily limited as long as the temperature is within a range not impairing the effects of the present invention. Here, in the coating film after sintering, it is better that the remaining amount of the organic matter is small in terms of obtaining as high strength as possible, but a part of the organic matter remains within a range not impairing the effect of the present invention. It doesn't matter.

(4) Joining method If the inorganic particle dispersion of this embodiment is used, high joining strength can be obtained in joining of members accompanied by heating. That is, between the 1st to-be-joined member and the 2nd to-be-joined member, the bonding composition application | coating process which apply | coats an inorganic particle dispersion between the 1st to-be-joined member and the 2nd to-be-joined member, A first bonding member and a second bonding member by bonding the inorganic particle dispersion applied to the substrate by firing at a desired temperature (for example, 300 ° C. or less, preferably 150 to 250 ° C.) And can be joined.

  During this joining step, the first and second members to be joined can be pressurized in the direction in which they face each other, but sufficient joining strength can be obtained without any particular pressure. This is one of the advantages of the present invention. In addition, when firing, the temperature can be raised or lowered stepwise. It is also possible to apply a surfactant or a surface activator to the surface of the member to be joined in advance.

  As a result of intensive studies, the inventor used the above-described inorganic particle dispersion of the present embodiment as the inorganic particle dispersion in the inorganic particle dispersion coating step. It was found that the member to be joined can be more reliably joined with high joining strength (a joined body is obtained).

  Here, “application” of the inorganic particle dispersion of the present embodiment is a concept including both cases where the inorganic particle dispersion is applied in a planar form and applied (drawn) in a linear form. The shape of the coating film made of the inorganic particle dispersion before being applied and fired by heating can be made into a desired shape. Therefore, in the joined body of the present embodiment after firing by heating, the inorganic particle dispersion is a concept including both a planar joining layer and a linear joining layer. The bonding layer may be continuous or discontinuous, and may include a continuous portion and a discontinuous portion.

  The first member and the second member that can be used in the present embodiment are not particularly limited as long as they can be applied by applying an inorganic particle dispersion and baking by heating. However, it is preferable that the member has a 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 polyamide (PA), polyimide (PI), polyamideimide (PAI), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN). Examples thereof include polyester, polycarbonate (PC), polyethersulfone (PES), vinyl resin, fluororesin, liquid crystal polymer, ceramics, glass, metal and the like, and among them, a metal joined member is preferable. The metal bonded member is preferable because it is excellent in heat resistance and affinity with the inorganic particle dispersion of the present invention containing metal particles as a main component.

  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 selected as appropriate. In order to improve adhesion or adhesion, or for other purposes, a member on which a surface layer is formed or a member subjected to a surface treatment such as a hydrophilic 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, dipping, screen printing, spraying, bar coating, spin coating, ink jetting , Dispenser method, pin transfer method, stamping method, brush application method, casting method, flexo method, gravure method, offset method, transfer method, hydrophilic / hydrophobic pattern method, syringe method, etc. be able to.

  The coated film after coating as described above can be baked by heating to a temperature of 300 ° C. or less, for example, within a range that does not damage the member to be bonded, and a bonded body can be obtained. In the present embodiment, as described above, since the inorganic particle dispersion of the present embodiment is used, a bonding layer having excellent adhesion to a member to be bonded is obtained, and a strong bonding strength is more reliably ensured. can get.

  In the present embodiment, when the inorganic particle dispersion includes a binder component, the binder component is also sintered from the viewpoint of improving the strength of the bonding layer and the bonding strength between the bonded members. The main purpose of the binder component is to adjust the viscosity of the inorganic particle dispersion for application to various printing methods, and all the binder component may be removed by controlling the firing conditions.

  The method for performing the firing is not particularly limited. For example, the temperature of the inorganic particle dispersion applied or drawn on the bonded member using a conventionally known oven or the like is, for example, 300 ° C. or less. It can join by baking. The lower limit of the firing temperature is not necessarily limited, and is preferably a temperature at which the members to be joined can be joined and does not impair the effects of the present invention. Here, in the inorganic particle dispersion after firing, it is better that the residual amount of the organic matter is small in terms of obtaining as high a bonding strength as possible, but a part of the organic matter remains within the range not impairing the effect of the present invention. It does not matter.

  The inorganic particle dispersion of the present invention contains an organic substance. However, unlike the conventional one using thermosetting such as an epoxy resin, it does not obtain the bonding strength after firing by the action of the organic substance. As described above, sufficient bonding strength can be obtained by fusing the fused metal particles. For this reason, even after bonding, even if the remaining organic matter is deteriorated or decomposed / dissipated in a use environment higher than the bonding temperature, there is no risk of the bonding strength being lowered, and therefore the heat resistance is excellent. Yes.

  According to the inorganic particle dispersion of the present embodiment, since it is possible to realize a bonding having a bonding layer that exhibits high conductivity even by firing at a low temperature of, for example, about 150 to 250 ° C., it is relatively weak to heat. Members can be joined together. Further, the firing time is not particularly limited, and may be any firing time that can be bonded according to the firing temperature.

  In order to further enhance the adhesion between the member to be bonded and the bonding layer, a surface treatment of the member to be bonded may be performed. Examples of the surface treatment method include a method of performing dry treatment such as corona treatment, plasma treatment, UV treatment, and electron beam treatment, and a method of previously providing a primer layer and a conductive paste receiving layer on a substrate.

  As mentioned above, although typical embodiment of this invention was described, this invention is not limited only to these. For example, in the above embodiment, the metal colloid dispersion liquid using metal particles as inorganic particles has been described. For example, tin-doped indium oxide having excellent conductivity, thermal conductivity, dielectric property, ion conductivity, alumina, Inorganic particles such as barium titanate and iron iron phosphate can also be used.

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

Example 1
0.9 g of butylamine (Wako Pure Chemical Industries, Ltd., reagent grade 1, carbon number: 4, log P: 1.0) and hexylamine (Wako Pure Chemical Industries, Ltd. reagent grade, carbon number: 6, log P: 2.1) 2.5 g and 0.3 g of DISPERBYK-174 (manufactured by Big Chemie), which is a polymer dispersant, were mixed and stirred well with a magnetic stirrer to produce an amine mixture. Next, 3.0 g of silver oxalate was added while stirring. After the addition of silver oxalate, stirring was continued at room temperature to change the silver oxalate to a viscous white substance, and stirring was terminated when the change was found to be apparently finished (first step) ).

  The obtained mixed solution was transferred to an oil bath and heated and stirred at 120 ° C. The reaction with the generation of carbon dioxide started immediately after the start of stirring, and then stirring was performed until the generation of carbon dioxide was completed, thereby obtaining a suspension in which silver fine particles were suspended in the amine mixture (No. 1). 2 steps). Next, in order to replace the dispersion medium of the suspension, 10 mL of methanol is added and stirred, and then silver fine particles are precipitated and separated by centrifugation, and 10 mL of methanol is added to the separated silver fine particles, followed by stirring and centrifugation. Silver fine particles are precipitated and separated by separation, and 0.03 g (1.5% by weight based on silver solid content) of polymer dispersant SOLPERSE 16000 (made by Lubrizol) is added to 2.4 g of terpineol C. The mixture was dispersed in a mixture to obtain a silver fine particle dispersion 1.

[Evaluation test]
(1) Dispersibility The silver fine particle dispersion 1 obtained as described above is allowed to stand in a container, and after 1 day at room temperature, the presence or absence of precipitation and the state of the supernatant are visually observed. Dispersibility was evaluated. “○” when almost no sediment is observed under the container, “△” when a small amount of sediment is observed, and “×” when there is a clear difference in concentration between the top and bottom of the container and sediment is clearly observed. It was evaluated. The results are shown in Table 1. Here, room temperature is 25 ° C.

(2) Dilutability 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 particles were dispersed was evaluated as “◯”, the case where partial aggregation or a silver mirror was observed was evaluated as “Δ”, and the case where aggregation / precipitation occurred was evaluated as “×”. 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 plate viscometer (Anton Paar rheometer, MCR301). The measurement conditions were: measurement mode: shear mode, shear rate: 10 s ⁻¹ , measurement jig: cone 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 as described above is brush-coated on a slide glass to form a coating film, and conditions of 150 ° C. for 30 minutes or 200 ° C. for 30 minutes in a gear oven Was heated and fired to form a conductive film. The volume resistance value of this film was measured using a DC precision measuring instrument “portable double bridge 2769” manufactured by Yokogawa Meter & Instruments Co., Ltd. Specifically, based on the following formula, the volume resistance value was converted from the distance between the measurement terminals and the thickness of the conductive coating. The case where the volume resistance value was 20 μΩ · cm or less was evaluated as “◯”, and the case where the volume resistance value exceeded 20 μΩ · cm was evaluated as “X”. The results are shown in Table 1.
Formula: (Volume resistance value ρv) =
(Resistance value R) × (film width w) × (film thickness t) / (terminal distance L)

(5) Organic content measurement The content of the organic component contained in the silver fine particle dispersion 1 obtained as described above was measured by thermogravimetric analysis. Specifically, the solid content of the silver fine particle dispersion 1 was heated at a rate of temperature increase of 10 ° C./min, and the content of the organic component was specified as a weight loss amount from room temperature to 200 ° C. and 200 to 500 ° C. The results are shown in Table 1. Here, room temperature is 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 in place of dihydroterpinyl acetate. The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 3
Instead of 0.9 g of butylamine (Wako Pure Chemical Industries, Ltd., reagent grade 1, carbon number: 4, log P: 1.0), 3-methoxypropylamine (Wako Pure Chemical Industries, Ltd. reagent grade 1, carbon number) : 4, log P: -1.5) Silver fine particle dispersion 3 was obtained in the same manner as in Example 2 except that 0.9 g was used. The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 4
A silver fine particle dispersion 4 was obtained in the same manner as in Example 3 except that terpinyloxyethanol (Telsolve TOE-100: Nippon Terpene Chemical Co., Ltd.) was used instead of dihydroterpineol. The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 5
The polymer dispersant added to terpinyloxyethanol (Telsolve TOE-100: Nippon Terpene Chemical Co., Ltd.) is 0.06 g of BYK-P104 (produced by BYK Chemie) with an active ingredient of 50% from SOLPERSE 16000 (based on the silver solid content). A silver fine particle dispersion 5 was obtained in the same manner as in Example 4 except that 1.5 wt%). The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 6
A silver fine particle dispersion 6 was obtained in the same manner as in Example 4 except that dihydroterpinyloxyethanol was used instead of terpinyloxyethanol (Telsolve TOE-100: Nippon Terpene Chemical Co., Ltd.). The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 7
Except that the amount of the polymer dispersant SOLPERSE 16000 added to dihydroterpinyloxyethanol was changed from 0.03 g to 0.015 g (0.75 wt% based on the silver solid content), in the same manner as in Example 6. A silver fine particle dispersion 7 was obtained. The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 8
Dispersion of silver fine particles obtained in the same manner as in Example 2 except that the polymer dispersant added to dihydroterpineol was changed to SOLSPERSE18000 and the addition amount was 0.03 g (1.5 wt% based on silver solid content). Body 8 was obtained. The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 9
0.9 g of butylamine, 2.5 g of hexylamine and 0.3 g of SOLSPERSE16000 which is a polymer dispersant were mixed and stirred well with a magnetic stirrer to produce an amine mixture. Next, 3.0 g of silver oxalate was added while stirring. After the addition of silver oxalate, stirring was continued at room temperature to change the silver oxalate to a viscous white substance, and stirring was terminated when the change was found to be apparently finished (first step) ).

  The obtained mixed solution was transferred to an oil bath and heated and stirred at 120 ° C. The reaction with the generation of carbon dioxide started immediately after the start of stirring, and then stirring was performed until the generation of carbon dioxide was completed, thereby obtaining a suspension in which silver fine particles were suspended in the amine mixture (No. 1). 2 steps). 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 then silver fine particles are precipitated and separated by centrifugation. Again, 10 mL of a mixed solvent of methanol / acetone (ratio 4: 1) was added, and the mixture was stirred and centrifuged to precipitate and separate silver fine particles. The polymer dispersant was added to 2.4 g of dihydroterpinyloxyethanol. The amount of SOLPERSE 16000 was dispersed in a mixture of 0.002 g (0.1% by weight based on the silver solid content) and mixed to obtain a silver fine particle dispersion 9. The same evaluation test as in Example 1 was performed, and the results are shown in Table 1.

Example 10
A silver fine particle dispersion 10 obtained in the same manner as in Example 1 was obtained except that 0.3 g of SOLPERSE 16000 was added instead of DISPERBYK-174 and dihydroterpineol was used instead of terpineol C. The same evaluation test as in Example 1 was performed, 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 as a dispersion medium. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

≪Comparative example 2≫
Comparative silver fine particle dispersion 2 was obtained in the same manner as in Comparative Example 1 except that 0.3 g of SOLPERSE 16000 was added instead of DISPERBYK-174. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

«Comparative Example 3»
Comparative silver fine particle dispersion 3 was obtained in the same manner as in Comparative Example 1 except that dihydroterpineol was used in place of terpineol C as the dispersion medium. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

<< Comparative Example 4 >>
0.9 g of butylamine (Wako Pure Chemical Industries, Ltd., reagent grade 1, carbon number: 4, log P: 1.0) and hexylamine (Wako Pure Chemical Industries, Ltd. reagent grade, carbon number: 6, log P: 2.1) Comparative silver fine particle dispersion 4 was obtained in the same manner as Comparative Example 2 except that 2.5 g was not used. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

<< Comparative Example 5 >>
Comparative silver fine particle dispersion 5 was obtained in the same manner as in Comparative Example 2 except that terpinyloxyethanol (Telsolve TOE-100: Nippon Terpene Chemical Co., Ltd.) was used instead of the dispersion medium dihydroterpineol. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

<< Comparative Example 6 >>
Comparative silver fine particle dispersion 6 was obtained in the same manner as Comparative Example 2 except that dihydroterpinyloxyethanol was used instead of the dispersion medium terpinyloxyethanol (Telsolve TOE-100: Nippon Terpene Chemical Co., Ltd.). It was. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

<< Comparative Example 7 >>
Comparative silver fine particles obtained in the same manner as in Example 10 except that the polymer dispersant added to dihydroterpineol was changed to SOLSPERSE11200 and the addition amount was 0.03 g (1.5% by weight based on the silver solid content). Dispersion 7 was obtained. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

«Comparative Example 8»
Comparative silver fine particle dispersion was carried out in the same manner as in Example 8 except that 0.06 g (1.5 wt% based on silver solid content) of BYK-P105 (manufactured by Big Chemie) was used as the polymer dispersant added to dihydroterpineol. Body 8 was obtained. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

<< Comparative Example 9 >>
Except that the amount of the polymer dispersant SOLPERSE 16000 added to dihydroterpinyloxyethanol was changed from 0.03 g to 0.001 g (0.05% by weight based on the silver solid content), in the same manner as in Example 9. A comparative silver fine particle dispersion 9 was obtained. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

<< Comparative Example 10 >>
0.9 g of butylamine, 2.5 g of hexylamine and 0.4 g of SOLSPERSE16000, which is a polymer dispersant, were mixed and stirred well with a magnetic stirrer to produce an amine mixture. Next, 3.0 g of silver oxalate was added while stirring. After the addition of silver oxalate, stirring was continued at room temperature to change the silver oxalate to a viscous white substance, and stirring was terminated when the change was found to be apparently finished (first step) ).

  The obtained mixed solution was transferred to an oil bath and heated and stirred at 120 ° C. The reaction with the generation of carbon dioxide started immediately after the start of stirring, and then stirring was performed until the generation of carbon dioxide was completed, thereby obtaining a suspension in which silver fine particles were suspended in the amine mixture (No. 1). 2 steps). Next, in order to replace the dispersion medium of the suspension, 10 mL of methanol is added and stirred, and then silver fine particles are precipitated and separated by centrifugation. Then, 10 mL of methanol is added again to the separated silver fine particles, and the mixture is stirred. Centrifugation was performed to precipitate and separate the silver fine particles, thereby obtaining a comparative silver fine particle dispersion 10 dispersed in 2.4 g of dihydroterpinyloxyethanol.

<< Comparative Example 11 >>
Comparative silver fine particles in the same manner as in Example 6 except that the amount of the polymer dispersant SOLPERSE 16000 added to dihydroterpinyloxyethanol was changed from 0.03 g to 0.3 g (15 wt% based on the silver solid content). Dispersion 11 was obtained. The same evaluation test as in Example 1 was performed, and the results are shown in Table 2.

  As can be seen from 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 particles) using dihydroterpinyl acetate having a low viscosity as a solvent. Except for the dispersion 10), it has a high viscosity of 15 mPa · s or more at 25 ° C. In addition, it has excellent dispersibility and dilutability. Furthermore, it shows a good (sufficiently low) volume resistivity value, and it has been found that an inorganic particle dispersion that has both excellent dispersion stability and high viscosity and can be fired at a relatively low temperature is obtained. .

  On the other hand, when no protective dispersant is added afterwards (comparative inorganic particle dispersions 1 to 3), sufficient dispersibility and dilutability are not obtained. Further, in the comparative silver fine particle dispersion 4 to which no short-chain amine having 6 or less carbon atoms is added, silver particles cannot be obtained.

  When a terpene ether type (terpinyloxyethanol, dihydroterpinyloxyethanol) is used as a dispersion medium without adding a protective dispersant (comparative silver fine particle dispersions 5 and 6), the inorganic fine particles are dispersed. A particle dispersion could not be obtained. On the other hand, the dispersibility of silver fine particles with respect to terpene ethers (terpinyloxyethanol, dihydroterpinyloxyethanol) is remarkably improved by adding a protective dispersant after the synthesis of silver fine particles (silver fine particle dispersion). Body 4-7, 9).

  From the comparison of the silver fine particle dispersions 6, 7, 9 and the comparative silver fine particle dispersion 11, it can be seen that the addition amount of the protective dispersant affects the conductivity and dispersibility. Specifically, when the addition amount is too large, the dispersibility is good, but it is not conductive. When the addition amount is too small, the volume resistance value is lowered but the dispersibility is inferior.

  Further, when the protective dispersant has no acid value (comparative silver fine particle dispersion 7) and when the acid value is too high (comparative silver fine particle dispersion 8), sufficient dispersibility is not obtained.

  It can be seen from the silver fine particle dispersion 9 that the dispersibility is improved by optimizing the cleaning solvent.

Claims (9)

Inorganic particles having a short-chain amine having 6 or less carbon atoms on at least a part of the surface;
A polymer having a comb-like structure having a pigment affinity group in the main chain and / or a plurality of side chains and having a plurality of side chains constituting a solvation part, a plurality of pigment affinity groups in the main chain A polymer dispersant containing a polymer having a pigment affinity part, or a linear polymer having a pigment affinity part composed of a pigment affinity group at one end of the main chain;
A dispersion medium,
A polymer protective dispersant having an acid value in the dispersion medium,
The acid value of the protective dispersant is 1 to 200,
The addition amount of the protective dispersant is 0.1 to 10% by weight or less based on the solid content of the inorganic particles,
The dispersion medium is a terpene material;
The viscosity is 15 mPa · s or more,
Obtained by adding the protective dispersant to the inorganic particles after the production of the inorganic particles,
An inorganic particle dispersion characterized by the above. The short-chain amine comprises an alkylamine and / or an alkoxyamine;
The inorganic particle dispersion according to claim 1. The short chain amine is at least one selected from the group consisting of butylamine, pentylamine, hexylamine, 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, 4-methoxybutylamine. There is,
The inorganic particle dispersion according to claim 1, wherein: The content of the dispersion medium is 1 to 90% by mass,
The inorganic particle dispersion according to any one of claims 1 to 3. The dispersion medium is a group consisting of terpineol, dihydroterpineol, dihydroterpinyl acetate, p-cymene, pinene, pinane, limonene, isobornyl acetate, carveol, caryophyllene, terpinyloxyethanol, dihydroterpinyloxyethanol. Being at least one kind selected,
The inorganic particle dispersion according to any one of claims 1 to 4. The weight reduction rate when heated from room temperature to 200 ° C. by thermal analysis is 5% or less, and the weight reduction rate when heated from 200 ° C. to 500 ° C. is 10% or less,
The inorganic particle dispersion according to any one of claims 1 to 5. The dispersion medium contains 0.5 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 6. The fatty acid is at least one selected from the group consisting of stearic acid, oleic acid, linoleic acid, linolenic acid and ricinoleic acid;
The inorganic particle dispersion according to claim 7 . The terpene material is a terpene ether material,
The inorganic particle dispersion according to any one of claims 1 to 8.