TWI820245B - Coated particles, conductive material containing the same, and method for producing coated particles - Google Patents

Abstract

An object of the present invention is to provide coated particles with an insulating layer covering the surface of conductive particles and excellent adhesion between the surface of the conductive particles and the insulating layer. The coated particles of the present invention are conductive particles that have a metal film formed on the surface of a core material and a titanium-based compound having a hydrophobic group disposed on the surface of the metal film opposite to the core material, and the conductive particles are coated The particles are coated with an insulating layer, and the insulating layer has a compound containing a charged functional group. The insulating layer is preferably composed of a plurality of fine particles arranged in a layered manner, or is a continuous film. In addition, the hydrophobic group may be an aliphatic hydrocarbon group having 2 to 30 carbon atoms.

Description

Coated particles, conductive material containing the same, and method for producing coated particles

The present invention relates to coated particles in which conductive particles are covered with an insulating layer.

Conductive particles in which a metal film of nickel, gold, or the like is formed on the surface of resin particles are used as conductive materials such as conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives. In recent years, as electronic equipment has been further miniaturized, the circuit width and pitch of electronic circuits have gradually become smaller. Therefore, the conductive particles used for the above-mentioned conductive adhesive, anisotropic conductive film, anisotropic conductive adhesive, etc. need to have a small particle size. When using conductive particles with such a small particle diameter, in order to improve continuity, it is necessary to increase the amount of conductive particles blended in the conductive material. However, if the amount of conductive particles is increased, electricity is supplied in an undesired direction, that is, in a different direction between the counter electrode and the electrode, causing a short circuit and making it difficult to obtain insulation in that direction.

In order to solve the above problem, the surface of the conductive particles is covered with an insulating substance having a functional group having affinity for the metal film, and the conductive particles are coated with an insulating layer that prevents the metal films of the conductive particles from coming into contact with each other. It is known that the surface of such conductive particles is previously treated with an organic treatment agent before the metal surface is covered with an insulating substance.

For example, Patent Document 1 describes that the metal surface of conductive particles is treated with a rust inhibitor, and insulating particles having hydroxyl groups are allowed to adhere to the treated conductive particles. Patent Document 2 describes that the metal surface of conductive particles is treated with a triazole compound, and insulating particles having ammonium groups are adhered to the treated conductive particles. [Patent Document]

Patent Document 1: Special Publication No. 2014-29857 Patent Document 2: International Publication No. 2016/063941

Regarding the conductive particles covered with insulating particles, improvement of the adhesion between the insulating particles and the conductive particles is an issue. The adhesion between the insulating particles and the conductive particles is important in order to obtain insulation in different directions from the counter electrode and achieve electrical conduction between the counter electrodes (hereinafter also simply referred to as connection reliability). In this regard, Patent Documents 1 and 2 treat the metal surface of the conductive particles with an organic treatment agent for the purpose of preventing rust and oxidation, and do not consider the adhesion between the insulating particles and the conductive particles. Therefore, an object of the present invention is to provide insulating layer-coated conductive particles that can solve the problems of the conventional technology described above.

As a result of intensive research by the present inventors in order to solve the above problems, when an insulating layer containing a functional group having a charge is used, and a titanium-based compound having a hydrophobic group is provided on the surface of the conductive particles, the insulating layer and the titanium-based compound will be The conductive particles have excellent affinity, and the coverage ratio of the conductive particles with the insulating material is further increased compared to the conventional technology, and thus the present invention was completed.

That is, the present invention provides conductive particles having a metal film formed on the surface of a core material, a titanium-based compound having a hydrophobic group disposed on the outer surface of the metal film, and the conductive particles coating the titanium-based compound. The particles are coated with an insulating layer on the surface of the particles, and the insulating layer has coated particles containing a compound containing a functional group having a charge.

[Mode for carrying out the invention]

Below, description will be given based on preferred embodiments of the present invention. The coated particles in this embodiment include conductive particles in which a metal film is formed on the surface of a core material, a titanium-based compound having a hydrophobic group is disposed on the outer surface of the metal film, and an insulating layer covering the conductive particles. covered particles, The insulating layer has a compound containing a charged functional group. The outer surface of the metal film means the surface on the opposite side of the metal film and the core material.

As the conductive particles, those conventionally used for conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives can be used. The core material of the conductive particles may be in the form of particles, or may be inorganic or organic, and is not particularly limited. Inorganic core particles such as metal particles of gold, silver, copper, nickel, palladium, solder, alloys, glass, ceramics, silica, metal or non-metal oxides (including hydrates), aluminum-containing silicic acid Salts include metal silicate, metal carbide, metal nitride, metal carbonate, metal sulfate, metal phosphate, metal sulfide, metal acid salt, metal halide and carbon, etc. On the other hand, organic core particles include natural fibers, natural resins, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutylene, polyamide, polyacrylate, polyacrylonitrile, polyacetal, Thermoplastic resins such as ionomers and polyesters, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, and diene phthalates Diallylphthalate resin, etc. These can be used individually or in combination of 2 or more types. Among these, core particles made of a resin material are preferred because they have a smaller specific gravity and are less likely to settle than core particles made of metal, have excellent dispersion stability, and can easily maintain electrical connection due to the elasticity of the resin. .

When an organic substance is used as the core particle, there is no glass transition temperature or glass transition from the viewpoint that the shape of the core particle can be easily maintained in the anisotropic conductive connection step and the shape of the core particle can be easily maintained in the metal film forming step. The temperature is better than 100℃. When the core material particles have a glass transition temperature, the glass transition temperature is preferably 200°C or less from the viewpoint that the conductive particles are easily softened during the anisotropic conductive connection, thereby enlarging the contact area and making it easier to conduct electricity. From this point of view, when the core material particles have a glass transition temperature, the glass transition temperature is preferably in the range of 100°C to 180°C, and particularly preferably in the range of 100°C to 160°C. The glass transition temperature can be measured by the method described in the Examples described below.

When an organic substance is used as the core particle, and the organic substance is a highly cross-linked resin, even if the glass transition temperature is measured to 200°C as described in the following examples, it is almost never observed. In this specification, such particles are also called particles without a glass transition point. The above-mentioned specific example of the core particle material having no glass transition temperature can be obtained by copolymerizing the monomer constituting the organic substance and the cross-linkable monomer as exemplified above. Cross-linking monomers such as tetramethylene di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate Ester, ethylene oxide di(meth)acrylate, tetraethylene oxide (meth)acrylate, 1,6-hexane di(meth)acrylate, neopentyl glycol di(meth)acrylate Ester, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, tetramethylolmethane tri(meth)acrylate Methacrylate, tetramethylolmethane tetra(meth)acrylate, tetramethylolpropane tetra(meth)acrylate, dineopenterythritol penta(meth)acrylate, glycerol di(meth)acrylate ) polyfunctional (meth)acrylates such as acrylate and glyceryl tri(meth)acrylate; multifunctional vinyl monomers such as divinylbenzene and divinyltoluene; vinyltrimethoxysilane, trimethoxysilane, etc. Silane-containing monomers such as silyl styrene, γ-(meth)acryloxypropyltrimethoxysilane; triallyl isocyanurate (triallyl isocyanurate), diallyl orthophenyl Monomers such as dicarboxylate, diallyl acrylamide, diallyl ether, etc. Especially in the COD (Chip on Glass) field, core particles made of such hard organic materials are often used.

The shape of the core particles is not particularly limited. Generally speaking, core particles are spherical. However, the core particle may have a shape other than spherical shape, such as fiber shape, hollow shape, plate shape, or needle shape, or may have a plurality of protrusions on the surface or may be amorphous. In the present invention, spherical core particles are preferred from the viewpoint of excellent filling properties and easy metal coating. The shape of the conductive particles also depends on the shape of the core material particles, but is not particularly limited. For example, it may be fibrous, hollow, plate-shaped or needle-shaped, or may have protrusions or irregular shapes on its surface. In the present invention, from the viewpoint of excellent filling properties and continuity, a spherical shape or a shape with protrusions on the surface is preferred. When the conductive particles have a shape with protrusions on the surface, it is preferable that the surface has a plurality of protrusions, and it is more preferable that the conductive particles have a plurality of protrusions on the surface. When the conductive particles have a shape with a plurality of protrusions, the core material particles may have a plurality of protrusions, or the core material particles may have no protrusions and the metal film may have a plurality of protrusions. Preferably, the core material particles have no protrusions and the metal film has a plurality of protrusions.

In the coated particles of the present invention, a titanium-based compound is disposed on the surface of the metal film, and the insulating layer has a compound containing a functional group with charge. The insulating layer has excellent adhesion to the conductive particles. In order to ensure reliable conduction of electricity, the surface of the conductive particles is also May have protrusions. By having protrusions on the surface of the conductive particles, when the conductive particles are compressed by the electrodes during packaging, the insulating layer can be effectively pushed out through the protrusions. From the viewpoint of eliminating the insulating layer during packaging and ensuring reliable conduction of electricity, when the height of the protrusions of the conductive particles is denoted as H and the thickness of the insulating layer is denoted as L, H/L is preferably 0.1 or more. From the viewpoint of obtaining filling properties and insulation properties in different directions from the counter electrode, H/L is preferably 10 or less. From these viewpoints, H/L is more preferably 0.2 or more and 5 or less. In these preferred ranges, the thickness L refers to the average particle size of the insulating fine particles when the insulating layer is made of insulating fine particles.

The height H of the protrusions is preferably 20 nm or more on average, particularly 50 nm or more. The number of protrusions may be 1 to 20,000 per particle, particularly 5 to 5,000, depending on the particle size of the conductive particles, from the viewpoint of further increasing the conductivity of the conductive particles. Moreover, the aspect ratio of the protrusion is preferably 0.3 or more, more preferably 0.5 or more. A larger aspect ratio of the protrusion is advantageous because it can easily break through the oxide film formed on the electrode surface. The aspect ratio is the ratio of the height H of the protrusion to the length D of the base of the protrusion, that is, the value defined by H/D. The height H of the protrusions and the length D of the base of the protrusions are the average values measured for 20 different particles observed with an electron microscope. The aspect ratio of the protrusions is the calculated length-to-width ratio of 20 different particles observed with an electron microscope. Ratio and find the average value. The length D of the base is the length of the protruding base along the surface of the conductive particle under an electron microscope.

The aspect ratio of the protrusions formed on the surface of the conductive particles is as described above. The base length D of the protrusions is preferably 5 to 500 nm, particularly 10 to 400 nm. The height H of the protrusions is 20 to 500 nm, particularly 50 to 50 nm. 400nm is better.

Conductive particles with protrusions on their surface, and when the insulating layer is insulating fine particles, some of the protrusions are insufficiently covered. Since the titanium-based compound used in the coated particles of the present invention itself exhibits insulating properties as will be described later, by arranging the titanium-based compound on the outer surface of the metal film, the insulating properties of the conductive particles having protrusions on the surface can be further improved.

The metal film of the conductive particles is conductive, and its constituent metals include gold, platinum, silver, copper, iron, zinc, nickel, tin, lead, antimony, bismuth, cobalt, indium, titanium, germanium, aluminum, chromium, Metals such as palladium, tungsten, and molybdenum or alloys thereof, or metal compounds such as ITO and solder, etc. Among these, gold, silver, copper, nickel, palladium or solder are preferred because of their low resistance, and particularly gold, silver, copper, nickel, palladium, gold alloy, silver alloy, copper alloy, nickel alloy or palladium alloy. It is preferably used because it has high bonding properties with the charged functional groups in the insulating fine particles, and it is preferable to include at least one kind selected from these metals. The metal in the metal film of the conductive particles may be used alone or in combination of two or more types.

The metal film may have a single-layer structure or a laminated structure composed of multiple layers. In the case of a laminated structure composed of a plurality of layers, it is preferable that the outermost layer is made of gold, silver, copper, nickel, palladium, gold alloy, silver alloy, copper alloy, nickel alloy or palladium alloy.

The metal film may not cover the entire surface of the core particle, or may cover only a part thereof. When only a part of the core particle surface is covered, the covered portion may be continuous or discontinuously covered like an island. The thickness of the metal film is preferably 0.001 μm or more and 2 μm or less. When the metal film has protrusions, the thickness of the metal film here does not include the height of the protrusions.

Methods for forming a metal film on the surface of core particles include, for example, dry methods such as vapor deposition, sputtering, mechanochemical methods, and mixing methods, and wet methods such as electroplating and electroless plating. Furthermore, these methods may be combined to form a metal film on the surface of the core particle.

The conductive particles have a titanium-based compound on the outer surface of the metal film. When the titanium-based compound is present on the surface of the conductive particles, it is easy to adhere to the insulating layer having charge. Therefore, the coverage ratio of the surface of the conductive particles with the insulating layer can be sufficient and the separation of the insulating layer from the conductive particles can be effectively prevented. Therefore, the effect of preventing a short circuit in a direction different from that of the counter electrode due to the insulating layer is easily exerted, and improvement in insulation properties in this direction can be expected. Therefore, the connection reliability is further improved through the coated particles of the present invention.

The titanium-based compound is preferably a compound having a hydrophobic group from the viewpoint of affinity with the insulating layer. The hydrophobic group of the titanium-based compound is, for example, an organic group, and the number of carbon atoms is preferably 2 or more and 30 or less, for example, from the viewpoint of easy availability and affinity with the insulating layer. From the same viewpoint, preferred examples of the hydrophobic group of the titanium-based compound include an aliphatic hydrocarbon group having 2 to 30 carbon atoms, an aryl group having 6 to 22 carbon atoms, and an aralkyl group having 7 to 23 carbon atoms. base. The above-mentioned aryl group or aralkyl group may be substituted with an aliphatic hydrocarbon group having 1 to 18 carbon atoms. The above-mentioned aliphatic hydrocarbon group having 2 to 30 carbon atoms includes, for example, a linear or branched saturated aliphatic hydrocarbon group and an unsaturated aliphatic hydrocarbon group. Examples of the saturated aliphatic hydrocarbon group include methyl, ethyl, and propyl. , butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl , octadecyl, nonadecyl, eicosyl, twenty-eicosyl, behenyl, etc. Examples of unsaturated aliphatic hydrocarbon groups, such as alkenyl groups, such as dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, nonadecenyl, tetradecenyl Alkenyl (icosenyl), eicosenyl (eicosenyl), icosenyl, icosenyl. Aryl groups having 6 to 22 carbon atoms include, for example, phenyl, tolyl, naphthyl, anthracenyl, etc. Aralkyl groups having 7 to 23 carbon atoms include benzyl, phenethyl, naphthylmethyl, and the like. A linear or branched aliphatic hydrocarbon group is particularly preferred as the hydrophobic group, and a linear aliphatic hydrocarbon group is particularly preferred. From the viewpoint of improving the affinity between the insulating layer and the conductive particles, the aliphatic hydrocarbon group as the hydrophobic group is particularly preferably one having 4 or more and 28 or less carbon atoms, and most preferably 6 or more and 24 or less carbon atoms.

The titanium-based compound, for example, has the general formula (I) from the viewpoint that affinity between the insulating layer and the conductive particles can be easily obtained by existing on the surface of the conductive particles, and it can be easily dispersed in a solvent to uniformly treat the surface of the conductive particles. The compound of the structure shown is particularly preferred.

(R ¹² is a divalent or trivalent group, R ¹³ is an aliphatic hydrocarbon group with 4 to 28 carbon atoms, an aryl group with 6 to 22 carbon atoms, or an aromatic group with 7 to 23 carbon atoms. Alkyl group, p and r are integers above 1 and below 3 respectively, satisfying p+r=4, q is an integer of 1 or 2, when R ¹² is a divalent base, q is 1, when R ¹² is 3 When the basis of valence is 2, q is 2. When q is 2, the plural R ¹³ can be the same or different. * indicates bonding.)

The aliphatic hydrocarbon group having 4 to 28 carbon atoms represented by R ¹³ is an example of the aliphatic hydrocarbon group of the hydrophobic group.

The divalent base represented by R ¹² is, for example, -O-, -COO-, -OCO-, -OSO ₂ -, etc. The trivalent group represented by R ¹² is, for example, -P(OH)(O-) ₂ , -OPO(OH)-OPO(O-) ₂ , etc.

In the general formula (I), * represents a bond, and the bond can be connected to the metal film of the conductive particle or to other atoms or groups. Other atoms or groups in this case are, for example, those described in the general formula (I') described below.

The titanium-based compound having the structure represented by the general formula (I) has a structure in which R ¹² in the general formula (I) is a divalent group from the viewpoint of being easily available and being able to be processed without impairing the conductive properties of the conductive particles. Compounds are better. The structure of a group in which R ¹² is a divalent group in the general formula (I) is represented by the following general formula (II).

(R ¹² is a group selected from -O-, -COO-, -OCO-, -OSO ₂ -, p, r and R ¹³ are as defined in general formula (I).)

In the general formulas (I) and (II), from the viewpoint of improving the adhesion between the insulating layer and the conductive layer, r is preferably 2 or 3, and r is 3 most optimally.

The titanium-based compound may or may not be chemically connected to the metal on the surface of the conductive particles. For example, the titanium-based compound may be chemically connected to the metal film through the bonds of the general formulas (I) and (II) mentioned above. In addition, chemical connection includes covalent bonding, electrostatic bonding, etc.

The titanium-based compound only needs to be present on the surface of the conductive particles. In this case, the titanium-based compound may be present on the entire surface of the conductive particles, or may be present on only a part of the surface. The titanium-based compound may form a layer covering part or all of the surface of the conductive particles. By having a titanium-based compound on the surface of the conductive particles, the particles have high affinity with the insulating layer having charged functional groups on the surface.

In order to have a titanium-based compound on the outer surface of the metal film of the conductive particles, a surface treatment of the conductive particles with a titanium-based compound may be performed in a preferable manufacturing method of coated particles described below.

The average particle diameter of the conductive particles is preferably from 0.1 μm to 50 μm, more preferably from 1 μm to 30 μm. When the average particle diameter of the conductive particles is within the above range, short circuits in different directions between the coated particles and the counter electrode will not occur, and it is easy to ensure electrical conduction between the counter electrodes. In addition, in the present invention, the average particle diameter of the conductive particles is the average value of the particle diameters measured using a scanning electron microscope (Scanning Electron Microscope: SEM). When the conductive particles are spherical under a scanning electron microscope, the particle diameter measured using the SEM is the diameter of the round conductive particles. When the insulating fine particles are not spherical, the particle diameter measured using SEM is the maximum length (maximum length) in the transverse line of the image of the conductive particles. However, when the conductive particles have protrusions, the above-mentioned maximum length is used as the average particle diameter for the portions other than the protrusions. Here, the average particle diameter of the insulating fine particles described below is also the same. Specifically, the average particle diameter of the conductive particles is measured according to the method described in the Examples.

The insulating layer of the present invention is composed of a polymer and has a compound containing a charged functional group. The insulating layer is composed of, for example, a plurality of insulating fine particles arranged in a layered manner, or is an insulating continuous film.

First, a description will be given of a case where the insulating layer is composed of insulating fine particles and the fine particles contain a compound having a charged functional group. In this case, by hot-pressing the coated particles between the electrodes, the insulating fine particles are melted, deformed, peeled off or moved on the surface of the conductive particles, and the metal surfaces of the conductive particles in the hot-pressed parts are exposed, thereby enabling electrical conduction between the electrodes. and gain continuity. On the other hand, the surface portions of the coated particles in directions other than the hot pressing direction usually maintain the coating state of the conductive particle surface with the insulating fine particles, thereby preventing the conduction of electricity in directions other than the hot pressing direction. Insulating fine particles contain charged functional groups on their surfaces (hereinafter simply referred to as "charged functional groups"), and are easily adhered to conductive particles having titanium-based compounds on their surfaces. Therefore, insulating particles can be insulated on the surface of the conductive particles. The coating ratio of the fine particles is sufficient, and the separation of the insulating fine particles from the conductive particles is effectively prevented. Therefore, the effect of preventing short circuits in different directions between the insulating fine particles and the counter electrode can be easily exhibited, and improvement in insulation properties in this direction can be expected. In addition, since the coated particles of the present invention have the same electric charge as the charged functional group, the insulating particles repel each other, so it is easy to form a single layer of insulating particles on the surface of the conductive particles. Therefore, when the coated particles of the present invention are used as anisotropic conductive materials, it is possible to effectively prevent poor conduction due to thermal stress caused by the presence of multiple layers of insulating fine particles, and it is expected that the continuity will be improved.

Therefore, according to the coated particles of the present invention in which the insulating layer is composed of insulating fine particles containing charged functional groups on the surface, the connection reliability is improved.

Insulating fine particles are preferably those having charged functional groups on their surfaces. In this specification, if the insulating microparticles have charged functional groups and it is confirmed that the insulating microparticles are adhered to the surface of the conductive particles by observation with a scanning electron microscope, it is equivalent to "the surface of the insulating microparticles has a charged functional group."

The shape of the insulating fine particles is not particularly limited, and may be spherical or may be in a shape other than spherical. Shapes other than spherical, such as fiber, hollow, plate or needle. The insulating fine particles may have a plurality of protrusions on the surface or may be amorphous. From the viewpoint of adhesion to conductive fine particles and ease of synthesis, spherical insulating fine particles are preferred.

The charged functional group of the insulating fine particles is preferably a part of the substance constituting the insulating fine particles and becomes a part of the chemical structure of the substance. It is preferable that the charged functional group of the insulating fine particles is included in the structure of the polymer constituting the insulating fine particles. The charged functional group is preferably chemically connected to the polymer constituting the insulating fine particles, and more preferably is connected to the side chain of the polymer. In this specification, if the insulating microparticles have charged functional groups and it is confirmed that the insulating microparticles are adhered to the surface of the conductive particles through scanning electron microscopy observation, it is equivalent to "the surface of the insulating microparticles has charged functional groups."

Among the charged functional groups, functional groups having a positive charge are preferably, for example, a phosphonium group, an ammonium group, a sulfonium group, an amine group, and the like. Furthermore, the functional group having a negative charge is preferably a carboxyl group, a hydroxyl group, a mercapto group, a sulfonic acid group, a phosphoric acid group, etc.

The charged functional group is particularly preferably an onium-based functional group such as a phosphonium group, an ammonium group, a sulfonium group, etc., from the viewpoint that conductive particles having a titanium-based compound or an amide-based compound on the surface adhere more closely to the insulating layer. Phosphonium base is the best.

The onium functional group is preferably represented by the following general formula (1), for example.

(In the formula, When X is a phosphorus atom, n is 1, and when X is a sulfur atom, n is 0. * is a bond.)

For example, as a counter ion having a positively charged functional group, a halide ion is preferred. Halide ions include Cl ^- , F ^- , Br ^- and I ^- .

R represents a linear alkyl group, such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-decyl Monoalkyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl base, n-eicosanyl, etc.

The branched alkyl group represented by R, such as isopropyl, isobutyl, second butyl, third butyl, isopentyl, second pentyl, third pentyl, isohexyl, second hexyl, Third hexyl, ethylhexyl, etc.

The cyclic alkyl group represented by R includes, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclooctadecyl and other cycloalkyl groups.

The aryl group represented by R includes, for example, phenyl, benzyl, tolyl, o-xylyl, etc.

From the viewpoint of improving the adhesion between the conductive particles and the insulating fine particles, and from the viewpoint that the insulating fine particles are detached from the conductive particles when the inside of the anisotropic conductive film is hot-pressed, making it easier to ensure electricity supply, R is a carbon number of 1 An alkyl group having a carbon number of 1 to 12 is preferred, an alkyl group having a carbon number of 1 to 10 is preferred, and an alkyl group having a carbon number of 1 to 8 is preferred. In addition, R may be a linear alkyl group from the viewpoint of making it easier for the insulating fine particles to approach and adhere closely to the conductive particles.

In the method of having a charged functional group on the surface of insulating fine particles, when the insulating fine particles are constituted by a polymer via a polymerizable composition composed of a polymerizable compound having an ethylenically unsaturated bond, the polymerizable composition contains a charged functional group. A polymerizable compound having a functional group and an ethylenically unsaturated bond is preferred.

The polymerizable compound having an ethylenically unsaturated bond constituting the polymerizable composition includes, for example, styrenes, olefins, esters, α,β unsaturated carboxylic acids, amides, nitriles, and the like. Styrenes such as styrene, o,m,p-methylstyrene, dimethylstyrene, ethylstyrene, chlorinated styrene and other core-substituted styrenes, or α-methylstyrene, α- Styrene derivatives such as chlorinated styrene and β-chlorinated styrene, etc. Olefins such as ethylene, propylene, etc. Esters include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate, and methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylate. Esters of (meth)acrylic acid such as phenyl acrylate, etc. α,β unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc. The salts of these α,β unsaturated carboxylic acids are also included in α,β unsaturated carboxylic acids. Amides include acrylamide, methacrylamide, etc. Nitriles such as acrylonitrile, etc. These may also be further substituted with substituents such as phosphonium group, amine group, quaternary ammonium group, amide group, sulfonyl group, sulfonate group, mercapto group, carboxyl group, phosphate group, cyano group, aldehyde group, ester group, carbonyl group, etc. . These monomers can be used 1 type or in combination of 2 or more types. The polymer constituting the insulating fine particles is preferably a polymer of at least one polymerizable monomer selected from the group consisting of styrenes, esters, and nitriles, in view of a high polymerization rate and ease of forming into a spherical shape. . When the polymer constituting the insulating microparticles has a plurality of structural units, the existence state of the structural units in the polymer may be random, alternating, or block-like. The polymer constituting the insulating fine particles may be cross-linked or not cross-linked. When the polymer constituting the insulating fine particles is cross-linked, the cross-linking agent may be aromatic divinyl compounds such as divinylbenzene or divinylnaphthalene; allyl methacrylate, hexahydro-1,3, 5-Tris(1-oxo-2-propenyl)-1,3,5-triazine (triacrylformal), triallyl isocyanate, ethylene glycol di(meth)acrylate, diethylene glycol di( Meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1, 10-Decanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate Ester, trimethylolpropane trimethacrylate, glyceryl dimethacrylate, dimethyloltricyclodecane diacrylate, neopentylerythritol tri(meth)acrylate, neopentylerythritol tetraacrylate Ester, dipenterythritol hexaacrylate, neopentyl glycol acrylate benzoate, trimethylolpropane acrylate benzoate, 2-hydroxy-3-propenyloxypropyl methacrylate, hydroxyl Di(meth)acrylate compounds such as trimethylacetate neopentyl glycol diacrylate, ditrimethylolpropane tetraacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, etc. .

Polymerizable compounds that contain charged functional groups and have ethylenically unsaturated bonds, such as polymeric compounds that have onium functional groups and have ethylenically unsaturated bonds, such as N,N-dimethylaminoethyl methacrylic acid Ammonium-containing monomers such as ester, N,N-dimethylaminopropylacrylamide, N,N,N-trimethyl-N-2-methacryloyloxyethylammonium chloride; Monomers containing strontium groups such as phenyldimethylsonium methacrylate methyl hydrochloride; 4-(vinylbenzyl)triethylphosphonium chloride, 4-(vinylbenzyl)trimethylphosphonium chloride compound, 4-(vinylbenzyl)tributylphosphonium chloride, 4-(vinylbenzyl)tributylphosphonium chloride, 4-(vinylbenzyl)triphenylphosphonium chloride, 2-( Methacryloxyethyl)trimethylphosphonium chloride, 2-(methacryloxyethyl)triethylphosphonium chloride, 2-(methacryloxyethyl)tributyl Phosphonium group-containing monomers such as phosphonium chloride, 2-(methacryloyloxyethyl)trioctylphosphonium chloride, 2-(methacryloyloxyethyl)triphenylphosphonium chloride, etc.

When the insulating fine particles are a copolymer of a polymerizable compound having a charged functional group and an ethylenically unsaturated bond, and a polymerizable compound having an ethylenically unsaturated bond that does not have a charged functional group, the polymerization of the charged functional group The polymerizable compound and the polymerizable compound having no charged functional group may be the same or different types. Such types include the aforementioned styrenes, olefins, esters, unsaturated carboxylic acids, amides, nitriles, etc. For example, at least one polymerizable compound having a charged functional group and an ethylenically unsaturated bond, and at least one polymerizable compound having no charged functional group and an ethylenically unsaturated bond may be of the same type, for example, styrene class.

In particular, from the viewpoint of easy availability of monomers or ease of polymer synthesis, the polymer constituting the insulating fine particles preferably has a structural unit represented by the following general formula (2) or general formula (3). Examples of R in formula (2) and formula (3) are the same as the examples of R in general formula (1) described above. The charged functional group can be connected to the CH group of the benzene ring of formula (2) in any of the para position, ortho position, and meta position, preferably in the para position. In formula (2) and formula (3), monovalent An ^- is preferably a halide ion. Halide ions include Cl ^- , F ^- , Br ^- and I ^- .

(In the formula, X, R, and n have the same definitions as in general formula (1). m is an integer from 0 to 5. ^{An -} represents a monovalent anion.)

(In the formula, X, R, and n have the same definitions as in general formula (1). An ^- represents a monovalent anion. m ¹ is an integer from 1 to 5. R ₅ is a hydrogen atom or a methyl group.)

In the polymer constituting the insulating fine particles, the proportion of the structural units connected to the charged functional groups is preferably 0.01 mol% or more and 5.0 mol% or less among the total structural units, and is preferably 0.02 mol% or more and 2.0 mol% or less. Better. Here, the number of structural units in the polymer is calculated using a structure derived from one ethylenically unsaturated bond as one structural unit.

In the above general formula (2), m is preferably 0 to 2, preferably 0 or 1, and particularly preferably 1. In the above general formula (3), m ¹ is preferably 1 to 3, more preferably 1 or 2, and most preferably 2.

The polymer constituting the insulating fine particles is a copolymer having two or more types of structural units, more preferably three or more types of structural units, and it is preferable that at least one of these structural units has an ester bond in the structure. According to this, the glass transition temperature of the polymer can be easily set to a preferably low one, the proportion of the area of the insulating fine particles in contact with the conductive particles can be increased, and the adhesion between the insulating fine particles and the conductive particles can be improved. The degree of bonding between insulating particles can further increase the insulation between coated particles.

The structural unit having an ester bond in the structure is, for example, derived from a polymerizable compound having an ethylenically unsaturated bond and an ester bond in the structure. Examples of the polymerizable compound include the esters listed above, specifically vinyl esters such as vinyl propionate and vinyl benzoate, or methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate. , (meth)acrylic acid esters such as butyl (meth)acrylate, hexyl (meth)acrylate, phenyl (meth)acrylate, etc. In particular, polymerizable compounds having ethylenically unsaturated bonds and ester bonds in their structure are preferred, and those having groups represented by -COOR ₁ or -OCOR ₂ (R ₁ and R ₂ are alkyl groups) in their structure are particularly preferred. Compounds connected to H ₂ C=CH* or H ₂ C=C(CH ₃ )* (* is the bonding position of the group represented by -COOR ₁ or -OCOR ₂ above) are preferred. R ₁ and R ₂ are preferably linear or branched alkyl groups, and preferably have a carbon number of 1 or more and 12 or less, and more preferably 2 or more and 10 or less carbon atoms. These can be used 1 type or in combination of 2 or more types.

In the polymer constituting the insulating fine particles, the proportion of the structural units having an ester bond in the structure among all the structural units, from the viewpoint of making the glass transition temperature of the insulating fine particles into a preferable range, and the From the viewpoint that the insulating fine particles are melted by heat and can be taken out without adhering to the wall surface of the reaction vessel, 0.1 mol% or more and 30 mol% or less is preferred, and 1 mol% or more and 25 mol% or less is more preferred. A preferred example of the structural unit having an ester bond in the above-mentioned structure is shown in the following general formula (4).

(In the formula, R ₃ is a hydrogen atom or a methyl group. _{R 4} is a group represented by -COOR ₁ or -OCOR _2. )

It is preferable that the glass transition temperature of the insulating fine particles is lower than the glass transition temperature of the core material of the conductive particles. Through such a structure, the ratio of the contact area between the insulating fine particles and the conductive particles can be easily increased, and the adhesion of the insulating fine particles to each other can be easily increased.

More specifically, the glass transition temperature of the insulating fine particles is preferably 100°C or lower, more preferably 95°C or lower, and particularly preferably 90°C or lower. From the viewpoint of the shape stability of the coated particles during storage and the ease of synthesis of the insulating fine particles, the glass transition temperature of the insulating fine particles is preferably 40°C or higher, more preferably 45°C or higher, and particularly preferably 50°C or higher. The glass transition temperature can be measured by the method described in the examples below.

From the same point of view as mentioned above, when the core material has a glass transition temperature, the difference between the glass transition temperature of the insulating fine particles and the glass transition temperature of the core material of the conductive particles is preferably 160°C or less, more preferably 120°C or less, and 100°C or less. Temperatures below ℃ are particularly good. The difference between the glass transition temperature of the insulating fine particles and the glass transition temperature of the core material of the conductive particles is preferably 5°C or more, and more preferably 10°C or more.

Measurement methods of glass transition temperature, such as the following method. Using a differential scanning calorimeter "STAR SYSTEM" (manufactured by METTLER TOLEDO), 0.04g~0.06g of the sample was heated to 200°C, and then cooled from this temperature to 25°C at a cooling rate of 5°C/min. Then, the sample was heated at a heating rate of 5°C/min, and the heat was measured. The peak temperature when a wave peak is observed, and when a step difference is observed without a wave peak, the intersection point of the tangent line showing the maximum slope of the curve showing the step difference part and the extension line of the baseline on the high temperature side of the step difference Temperature is the glass transition temperature.

The average particle diameter (D) of the insulating fine particles is preferably from 10 nm to 3,000 nm, and preferably from 15 nm to 2,000 nm. When the average particle diameter of the insulating fine particles is within the above range, short circuits in different directions between the coated particles and the counter electrode will not occur, and it is easy to ensure electrical conduction between the counter electrodes. In the present invention, the average particle diameter of the insulating fine particles is a value measured by observation using a scanning electron microscope, specifically by the method described in the Examples described below.

The particle size distribution of the insulating fine particles measured by the aforementioned method has a wide range. Generally speaking, the width of the particle size distribution of powder is represented by the coefficient of variation (Coefficient of Variation (hereinafter also referred to as "C.V.") represented by the following equation (1)). C.V.(%)=(standard deviation/average particle size)×100…(1) Those with a larger C.V. show a wider particle size distribution, while those with a smaller C.V. show a narrower particle size distribution. The coated particles in this embodiment preferably use insulating fine particles whose C.V. is preferably 0.1% or more and 20% or less, preferably 0.5% or more and 15% or less, and most preferably 1% or more and 10% or less. Since the C.V. is in this range, there is an advantage that the thickness of the coating layer formed by the insulating fine particles can be made uniform.

In addition, the insulating layer may be a continuous film formed of a polymer and having a charged functional group, instead of being formed of the above-mentioned insulating fine particles. When the insulating layer is a continuous film containing a compound with a charged functional group, the coated particles are hot-pressed between electrodes to melt, deform or peel off the continuous film to expose the metal surface of the conductive particles, thereby allowing the space between the electrodes to be exposed. Power up and get continuity. In particular, by hot-pressing coated particles between electrodes, the continuous film is often broken and the metal surface is exposed. On the other hand, since the surface portions in different directions from the hot-pressing direction of the coated particles generally maintain the covering state of the conductive particles formed by the continuous film, conduction in directions other than the hot-pressing direction can be prevented. It is preferable that the insulating film also has charged functional groups on the surface.

Even when the insulating layer is composed of a continuous film, since it has a charged functional group, the insulating continuous film easily adheres to the conductive particles having a titanium-based compound on the surface. Furthermore, when the continuous film is formed by heating insulating fine particles as described later or when the insulating fine particles covering the conductive particles are dissolved in an organic solvent, the insulating fine particles that become the precursor of the insulating layer can be uniformly arranged and the insulation can be penetrated. The melting or dissolving of the organic fine particles has the effect of making the film thickness of the resulting film uniform. For these reasons, even when the insulating layer is composed of a continuous film, since it contains a titanium-based compound and a charged functional group, it is easy to exert the effect of preventing short circuits in different directions between the counter electrode and the opposite electrode, thereby improving the insulation in that direction. Improve and become a continuous reliability improver. When the insulating layer is a continuous film containing a compound having a charged functional group, the film may cover the entire surface of the conductive particles, or may cover a part of the surface. The surface of the continuous film may be flat, or may have an uneven surface resulting from the melting or dissolution of the insulating fine particles.

From the viewpoint of improving insulation in different directions from the counter electrode, the thickness of the continuous film is preferably 10 nm or more, and from the viewpoint of easy conduction of electricity between the counter electrodes, the thickness is preferably 3,000 nm or less. From this point of view, the thickness of the continuous film is preferably from 10 nm to 3,000 nm, and more preferably from 15 nm to 2,000 nm.

Like the insulating fine particles, the charged functional groups in the continuous film are preferably part of the substance constituting the continuous film and become part of the chemical structure of the substance. In the continuous film, it is preferable that the charged functional group is included in at least one structure of the structural unit of the polymer constituting the continuous film. The charged functional group is preferably chemically connected to the polymer constituting the continuous film, and more preferably is connected to the side chain of the polymer. The charged functional groups of the continuous film are the same as the charged functional groups of the insulating fine particles described above. Examples of the structural units and compositions of the polymer constituting the continuous film are the same as the structural units and compositions of the polymer constituting the insulating microparticles described above. The preferred ratio ranges of the above structural units are all applicable to the continuous film. The glass transition temperature of the continuous film, such as the glass transition temperature of the above-mentioned insulating particles. The relationship between the glass transition temperature of the continuous film and the glass transition temperature of the core particles is the same as the relationship between the glass transition temperature of the insulating fine particles and the glass transition temperature of the core particles.

When the insulating layer is a continuous film, it is preferable to coat the conductive particles with insulating fine particles having charged functional groups on the surface, and then heat the insulating fine particles to obtain a continuous film. In this case, as described above, for the conductive particles, the insulating fine particles are easily adhered to the conductive particles. Therefore, the surface of the conductive particles is covered with a sufficient proportion of the insulating fine particles and it is easy to prevent the insulating fine particles from being peeled off from the conductive particles. Moreover, as mentioned above, insulating fine particles having a charged functional group can easily cover conductive particles with a single layer. For these reasons, the continuous film obtained by heating the insulating fine particles covering the conductive particles can have a uniform thickness and a high coating ratio on the surface of the conductive particles.

In addition, it was originally hoped that all the structures and properties of the continuous film obtained by heat treatment of specific insulating fine particles would be directly described in this description after being measured using a certain method. However, at least at the time of filing, the applicant's technical level was unable to confirm the structure or characteristics of other continuous films related to the effects of the present invention. Furthermore, even if all the factors are investigated, it will be necessary to establish a new measurement method and determine the structure and characteristics of the continuous film related to these factors, so obviously excessive economic expenditure and time will be required. Based on the above-mentioned facts and considering the nature of patent application, which requires expeditiousness, etc., the applicant states that the above-mentioned manufacturing method is one of the preferred features of the continuous film.

Hereinafter, a preferred method for manufacturing the coated particles according to this embodiment will be described. This production method has a first step of polymerizing a polymerizable composition containing a charged functional group to obtain insulating fine particles having a charged functional group on the surface, The second step of providing a titanium-based compound on the surface of conductive particles, and The third step is to mix a dispersion liquid containing insulating microparticles and conductive particles with a titanium-based compound on the surface to adhere the insulating microparticles to the surface of the conductive particles. Either step 1 or step 2 can be performed first or at the same time.

(Step 1) The polymerizable composition is composed of two or more polymerizable compounds, and for example, at least one of them contains a charged functional group. The polymerizable compound is, for example, a polymerizable compound having an ethylenically unsaturated bond as a structural unit of the polymer constituting the insulating fine particles. Furthermore, preferable polymerizable compounds and their structural proportions include the preferable structural units of the polymer constituting the insulating fine particles and their preferable quantitative ratios.

Any polymerization method may be used, such as emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, suspension polymerization, etc. However, soap-free emulsion polymerization is preferred because it can produce monodispersed microparticles without using surfactants. In the case of soap-free emulsion polymerization, a water-soluble initiator is used as the polymerization initiator. The polymerization is preferably carried out under an inert atmosphere such as nitrogen or argon. Through the above, insulating fine particles having charged functional groups on the surface are obtained.

(Step 2) Conductive particles having a titanium-based compound on their surface are obtained by mixing the titanium-based compound in a solvent and then filtering. The titanium-based compound used for surface treatment has, for example, the above-mentioned hydrophobic group, and preferably has the structure represented by the above-mentioned general formula (I). The compound having the structure represented by the general formula (I) is preferably a compound represented by the general formula (I'). Before being treated with a titanium-based compound, the conductive particles may be treated with other organic agents, or may not be treated.

(R ¹² , R ¹³ , p, q and r have the same definitions as in the general formula (I) above. R ¹¹ is a hydrocarbon group. When p is 2 or more, the plurality of R ¹¹ may be the same or different, or there may be two R ¹¹ connected to each other, the methylene group in the group represented by R ¹¹ can also be substituted by -O-, -COO- or -OCO-.)

In the general formula (I′), the hydrocarbon group represented by R ¹¹ is, for example, an alkyl group having 1 to 12 carbon atoms. When p is 2 or more, the connecting group of two R ¹¹ to each other is, for example, a group represented by -(CH ₂ ) _W - (w is an integer from 2 to 12). The methylene group in the group represented by R ¹¹ may be substituted once or twice or more by -O-, -COO- or -OCO-, provided that the oxygen atoms are discontinuous. The alkyl group having 1 to 12 carbon atoms represented by R ¹¹ includes, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, third butyl, etc.

A solvent for mixing conductive particles and a titanium-based compound, such as water or an organic solvent. Organic solvents include toluene, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran, acetonitrile, N-methylpyrrolidone, dimethylformamide, etc. In the dispersion liquid in which the conductive particles and the titanium-based compound are put into a solvent, the concentration of the titanium-based compound is, for example, 0.1 mass % or more and 20 mass % or less. The concentration of the conductive particles in this dispersion liquid is, for example, 1 mass% or more and 50 mass% or less. The treated dispersion liquid was filtered to obtain conductive particles having a titanium-based compound on the surface.

In the case of surface treatment with a titanium-based compound, the treatment can be performed by mixing conductive particles, a titanium-based compound, and a solvent at room temperature. Alternatively, the conductive particles and the titanium-based compound may be mixed in a solvent and then heated to promote hydrolysis. The heating temperature is, for example, 30°C or more and 50°C or less.

(Step 3) Next, the dispersion liquid containing the insulating fine particles and the conductive particles having the titanium-based compound on the surface are mixed, so that the insulating fine particles are adhered to the surface of the conductive particles. The vehicle for the dispersion liquid is water, organic solvents and their mixtures, preferably water, ethanol, or a mixture of ethanol and water.

From the viewpoint of easily obtaining coated particles with a coverage ratio of a certain level or more, the dispersion liquid preferably contains an inorganic salt, an organic salt or an organic acid. Inorganic salts, organic salts or organic acids are preferably used to dissociate anions. The anions are preferably Cl ^- , F ^- , Br ^- , I ^- , SO ₄ ^2- , CO ₃ ^2- , NO ₃ ^- , COO ^- , RCOO ^- (R is organic group) etc. Examples of inorganic salts that can be used include NaCl, KCl, LiCl, MgCl ₂ , BaCl ₂ , NaF, KF, LiF, MgF ₂ , BaF ₂ , NaBr, KBr, LiBr, MgBr ₂ , BaBr ₂ , NaI, KI, LiI, MgI ₂ , BaI ₂ , Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO ₄ , MgSO ₄ , Na ₂ CO ₃ , NaHCO ₃ , K ₂ CO ₃ , KHCO 3 , Li ₂ CO ₃ , LiHCO ₃ , MgCO _{3 ,} NaNO ₃ , KNO ₃ , LiNO ₃ , MgNO ₃ , BaNO ₃ , etc. Moreover, sodium oxalate, sodium acetate, sodium citrate, sodium tartrate, etc. can be used as an organic salt. As the organic acid, amino acids such as glycine, or succinic acid, oxalic acid, acetic acid, citric acid, tartaric acid, malonic acid, fumaric acid, maleic acid, etc. can be used.

Preferable concentrations of inorganic salts, organic salts, and organic acids vary depending on the coverage area occupied by the insulating fine particles in the surface area of the conductive particles. However, in the dispersion liquid after the conductive particles are mixed, for example, they are 0.1 mmol/L or more. , a concentration of 100 mmol/L or less is preferred because it has a better coverage rate and can easily obtain a single layer of coated particles with insulating fine particles. From this point of view, it is particularly preferred that the concentration of the inorganic salt, organic salt and organic acid in the dispersion is 1.0 mmol/L or more and 80 mmol/L or less.

When insulating fine particles and conductive particles are mixed in a vehicle liquid, a dispersion liquid containing insulating fine particles and conductive particles may be mixed, a dispersion liquid containing conductive particles and insulating fine particles may be mixed, or a dispersion liquid containing conductive particles may be mixed with insulating fine particles. The insulating fine particles and the conductive particles may be separately added to the vehicle liquid, or a dispersion liquid containing the insulating fine particles and a dispersion liquid containing the conductive particles may be mixed. In a dispersion containing conductive particles and insulating fine particles, it is preferable that the conductive particles contain 100 ppm or more and 100,000 ppm or less on a mass basis, and it is more preferable that the conductive particles contain 500 ppm or more and 80,000 ppm or less. In a dispersion containing conductive particles and insulating fine particles, it is preferable that the insulating fine particles contain 10 ppm or more and 50,000 ppm or less on a mass basis, and preferably 250 ppm or more and 30,000 ppm or less.

The temperature of the dispersion liquid at the time of mixing with the conductive particles is generally preferably 20°C or higher and 100°C or lower, and preferably 40°C or higher, from the viewpoint of easily obtaining coated particles of constant quality. In particular, when the glass transition temperature of the insulating fine particles is expressed as Tg°C, the temperature of the dispersion liquid is preferably Tg-30°C or more and Tg+30°C or less. This range is preferable because the insulating fine particles can maintain their shape and adhere closely to the conductive particles, making it easier to obtain a better contact area between the insulating fine particles and the conductive particles. In particular, the insulating fine particles having a charged functional group of the present invention have high affinity with the conductive particles, so they can be fully covered within the above temperature range.

In the dispersion liquid after mixing the conductive particles, the time required for adhesion of the insulating fine particles to the conductive particles is preferably 0.1 hour or more and 24 hours or less. It is best to stir the dispersion during this period. Next, if necessary, the solid content of the dispersion is washed and dried to obtain coated particles in which insulating fine particles having charged functional groups adhere to conductive particles.

As mentioned above, by heating the coating particles where the insulating particles adhere to the surface of the conductive particles, the insulating particles are brought into a molten state, and the surface of the conductive particles can be coated in a film form. Since the insulating particles are in the form of a film, the insulation becomes stronger. The heating method includes, for example, a method of heating the dispersion liquid after the insulating fine particles have adhered to the surface of the conductive particles, a method of heating the coated particles in a solvent such as water, and a method of heating the coated particles in a gas phase such as an inert gas. methods etc. The heating temperature is preferably Tg + 1°C or more and Tg + 60°C or less, when the glass transition temperature of the polymer constituting the insulating fine particles is expressed as Tg, so that the insulating fine particles do not fall off and are easily formed into a uniform film. It is better to have Tg+5℃ or above and below Tg+50℃, and it is best to exceed Tg+15℃. The heating time is preferably 0.1 hour or more and 24 hours or less from the viewpoint of easy formation of a uniform film. When the coated particles are heated in the gas phase, the pressure condition may be atmospheric pressure, reduced pressure, or increased pressure.

Coated particles in which insulating fine particles adhere to the surface of conductive particles can cause the insulating fine particles to flow even if an organic solvent is added to the dispersion, thereby coating the surface of the conductive particles in a film-like manner. When the insulating fine particles are dissolved, tetrahydrofuran, toluene, methyl ethyl ketone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, etc. can be used as the organic solvent. The added amount of the organic solvent is preferably 1 part by mass or more and less than 100 parts by mass relative to 1 part by mass of the coated particles in the dispersion liquid, and 5 parts by mass or more, from the viewpoint of preventing the insulating fine particles from falling off and easily forming a uniform film. , 50 quality parts or less is preferred. The addition temperature is preferably not less than 10°C and not more than 100°C, and more preferably not less than 20°C and not more than 80°C, from the viewpoint that the insulating fine particles do not fall off and are easily formed into a uniform film shape. The time from addition to film formation is preferably 0.1 hour or more and 24 hours or less from the viewpoint of forming a uniform film.

The coated particles that cover the surface of the conductive particles in a film form may be annealed in order to further stabilize the continuous film. An example of the annealing treatment method is a method of heating the coated particles in a gas phase such as an inert gas. When the glass transition temperature of the polymer constituting the insulating fine particles is expressed as Tg, the heating temperature is preferably Tg+1°C or more and Tg+60°C or less, and more preferably Tg+5°C or more and Tg+50°C or less. The heating atmosphere is not particularly limited, and the heating may be performed in an inert gas atmosphere such as nitrogen or argon or an oxidizing atmosphere such as air, under atmospheric pressure, reduced pressure, or increased pressure.

The preferred manufacturing method has been described above, but the coated particles of the present invention can also be manufactured by other manufacturing methods. For example, insulating fine particles having no charged functional groups may be produced by a polymerization reaction in advance, and the resulting insulating fine particles may be reacted with a compound having a charged functional group to introduce charged functional groups onto the surface of the insulating fine particles.

The coated particles obtained as above effectively utilize the insulation between the coated particles and the connection between the counter electrodes formed by combining the advantages of conductive particles having a titanium-based compound on the surface and insulating fine particles or a continuous film having a charged functional group. properties, it can be preferably used as a conductive material such as a conductive adhesive, an anisotropic conductive film, an anisotropic conductive adhesive, and the like. [Example]

The present invention is illustrated below through examples. However, the scope of the present invention is not limited to these examples. The characteristics in the example were measured using the following methods.

(1)Average particle size From a scanning electron microscope (SEM) photograph of the measurement object (magnification: 100,000 times for insulating fine particles and 10,000 times for conductive particles), 200 particles are randomly selected, and the above particle diameters are measured for these particles, and the average value is taken as the average particle diameter.

(2)C.V. (coefficient of variation) From the above measurement of the average particle diameter, it is determined according to the following formula. C.V.(%)=(standard deviation/average particle size)×100

(3)Glass transition temperature The heat change at a temperature of 25°C to 200°C was measured using a differential scanning calorimetry measuring device (STAR SYSTEM, manufactured by METTLER TOLEDO Co., Ltd.) at a heating and cooling rate of 5°C/min and a nitrogen atmosphere, and was measured according to the above steps.

(Example 1) [Production of phosphonium-based insulating fine particles] 100 mL of pure water was added to a 200 mL four-necked flask equipped with a 60 mm long stirrer. Thereafter, 30.00 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), 0.30 mmol of 4-(vinylbenzyl)triethylphosphonium chloride (manufactured by Nippon Chemical Industry Co., Ltd.), and and 0.50 mmol of the polymerization initiator 2,2'-azobis(2-methylpropionamidyl)dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.). Nitrogen was introduced for 15 minutes to remove dissolved oxygen, and then the temperature was raised to 60°C and maintained for 6 hours to carry out polymerization reaction. The dispersion liquid of the polymerized fine particles was passed through a SUS sieve with a mesh size of 150 μm to remove aggregates. The dispersion from which aggregates were removed was placed in a centrifuge (Hitachi Kogen, CR-21N) at 20,000 rpm for 20 minutes to sediment the fine particles, and the supernatant was removed. The obtained solid was washed with pure water to obtain spherical microparticles of poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride). The average particle diameter of the obtained microparticles was 86 nm, and the CV was 7.4%. The glass transition temperature is approximately 62°C. [Production of insulating fine particle-coated conductive particles] Nickel-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having a nickel film with a thickness of 0.125 μm and an average particle diameter of 3 μm on the surface of spherical resin particles were prepared. The resin particles are composed of cross-linked acrylic resin and have a glass transition temperature of 120°C. Add 5.0 g of the above-mentioned nickel-plated particles to 25 mL of toluene, and stir to obtain a dispersion of nickel-plated particles. Titanium-based coupling agent (Plenact KR-TTS manufactured by Ajinomoto Fine-Techno Co., Ltd., in the above general formula (I'), p is 3, r is 1, R ¹¹ is isopropyl, R ¹² is -OCO-, q= 1, R ¹³ is heptadecanyl compound) 0.1g, add this dispersion, stir at room temperature for 20 minutes to perform surface treatment. Thereafter, the particles were filtered through a membrane filter with a mesh size of 2.0 μm, and the nickel-plated particles having a titanium-based coupling agent layer on the surface were collected. Add 100 mL of a mixture of mass standard ethanol: pure water = 75:25 to the collected nickel-plated particles, perform surface treatment, and obtain a dispersion of nickel-plated particles. The insulating fine particles and Na ₂ SO ₄ obtained above were added to this dispersion, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the Na ₂ SO ₄ concentration was 5 mmol/L. After removing the supernatant, washing was repeated three times with pure water, and then vacuum dried at 50° C. to obtain insulating microparticle-coated conductive particles. The coverage ratio of the insulating fine particles in the obtained conductive particles was determined by the following method. The results are shown in Table 1. The SEM photograph of the obtained coated particles is shown in Figure 1.

(Example 2) [Production of phosphonium-based insulating fine particles] Insulating fine particles were obtained in the same manner as in Example 1. [Production of insulating fine particle-coated conductive particles] A nickel film having an average height of 0.1 μm on the surface of the spherical resin particles, an average bottom length of 0.197 μm, an aspect ratio of 0.5, 1,030 protrusions, and a thickness of 0.125 μm was prepared. , Nickel plating particles with an average particle diameter of 3 μm (manufactured by Nippon Chemical Industry). The resin particles are composed of cross-linked acrylic resin and have a glass transition temperature of 120°C. Add 5.0 g of the above-mentioned nickel-plated particles to 25 mL of toluene, and stir to obtain a dispersion of nickel-plated particles. Titanium-based coupling agent (Plenact KR-TTS manufactured by Ajinomoto Fine-Techno Co., Ltd., in the above general formula (I'), p is 3, r is 1, R ¹¹ is isopropyl, R ¹² is -OCO-, q= 1, R ¹³ is heptadecanyl compound) 0.1g, add this dispersion, stir at room temperature for 20 minutes to perform surface treatment. Thereafter, the particles were filtered through a membrane filter with a mesh size of 2.0 μm, and the nickel-plated particles having a titanium-based coupling agent layer on the surface were collected. Add 100 mL of a mixture of mass standard ethanol: pure water = 75:25 to the collected nickel-plated particles, perform surface treatment, and obtain a dispersion of nickel-plated particles. The insulating fine particles and Na ₂ SO ₄ obtained above were added to this dispersion, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the Na ₂ SO ₄ concentration was 5 mmol/L. After removing the supernatant, washing was repeated three times with pure water, and then vacuum dried at 50° C. to obtain insulating microparticle-coated conductive particles. The coverage ratio of the insulating fine particles in the obtained conductive particles was determined by the following method. The results are shown in Table 1.

(Example 3) [Production of phosphonium-based insulating fine particles] Insulating fine particles were obtained in the same manner as in Example 1. [Production of insulating microparticle-coated conductive particles] In addition to titanium-based coupling agent (Plenact KR-41B manufactured by Ajinomoto Fine-Techno Co., Ltd.), in the above general formula (I'), p is 3, r is 1, and R ¹¹ is different. Propyl, R ¹² is -P(OH)(O-) ₂ , q=1, R ¹³ is an octyl compound) 0.1g is added to the dispersion of nickel plated particles for surface treatment, the same method as in Example 1, Insulating fine particles coated conductive particles are obtained. The coverage ratio of the insulating fine particles in the obtained coated particles was determined by the following method. The results are shown in Table 1.

(Example 4) [Production of phosphonium-based insulating fine particles] Insulating fine particles were obtained in the same manner as in Example 1. [Production of insulating microparticle-coated conductive particles] In addition to titanium-based coupling agent (Plenact KR-41B manufactured by Ajinomoto Fine-Techno Co., Ltd.), in the above general formula (I'), p is 3, r is 1, and R ¹¹ is different. Propyl, R ¹² is -P(OH)(O-) ₂ , q=1, R ¹³ is an octyl compound) 0.1g is added to the dispersion of nickel plated particles for surface treatment, the same method as in Example 2, Insulating fine particles coated conductive particles are obtained. The coverage ratio of the insulating fine particles in the obtained coated particles was determined by the following method. The results are shown in Table 1.

(Example 5) 1.0 g of the insulating fine particle-coated conductive particles obtained in Example 1 was added to 20 mL of pure water to form a dispersion, and the dispersion was stirred at 95° C. for 6 hours. After stirring, the solid content was separated using a membrane filter with a mesh size of 2 μm and dried to obtain coated particles covered with an insulating layer formed by a continuous film with a maximum thickness of 50 nm and a minimum thickness of 20 nm. The coverage ratio of the insulating layer formed by the continuous film in the obtained coated particles was determined by the following method. The results are shown in Table 1.

(Example 6) [Production of phosphonium-based insulating fine particles] Add 100 mL of pure water to a 200 mL four-necked flask equipped with a 60 mm long stirrer. Thereafter, 15.0 mmol of divinylbenzene monomer (manufactured by Nippon Steel & Sumitomo Metal Co., Ltd.) as a cross-linkable monomer, 30.00 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.) as a non-cross-linkable monomer, and n-butyl acrylate ( Kanto Chemical Co., Ltd.) 5.3 mmol, 4-(vinylbenzyl)triethylphosphonium chloride (Nihon Chemical Industry Co., Ltd.) 0.03 mmol, and polymerization initiator 2,2'-azobis(2-methylpropionamidine) base) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.) 0.50 mmol. Nitrogen was introduced for 15 minutes to remove dissolved oxygen, and then the temperature was raised to 60°C and maintained for 6 hours to carry out polymerization reaction. The dispersion liquid of the polymerized fine particles was passed through a SUS sieve with a mesh size of 150 μm to remove aggregates. The dispersion from which aggregates were removed was placed in a centrifuge (Hitachi Kogen, CR-21N) at 20,000 rpm for 20 minutes to sediment the fine particles, and the supernatant was removed. The obtained solid was washed with pure water to obtain spherical microparticles of poly(styrene/divinylbenzene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride). The average particle size of the obtained microparticles was 220 nm, and the C.V. was 9.7%. [Production of conductive particles coated with insulating fine particles] In the same manner as in Example 1, insulating microparticle-coated conductive particles were obtained. The coverage ratio of the insulating fine particles in the obtained coated particles was determined by the following method. The results are shown in Table 1.

(Example 7) [Production of ammonium-based insulating fine particles] 100 mL of pure water was added to a 200 mL four-necked flask equipped with a 60 mm long stirrer. After that, 30.00 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), 0.30 mmol of 4-(vinylbenzyl)triethylammonium chloride (manufactured by Nippon Chemical Industry Co., Ltd.), and 0.50 mmol of the polymerization initiator 2,2'-azobis(2-methylpropionamidyl)dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.). Nitrogen was introduced for 15 minutes to remove dissolved oxygen, and then the temperature was raised to 60°C and maintained for 6 hours to carry out polymerization reaction. The dispersion liquid of the polymerized fine particles was passed through a SUS sieve with a mesh size of 150 μm to remove aggregates. The dispersion from which aggregates were removed was placed in a centrifuge (Hitachi Kogen, CR-21N) at 20,000 rpm for 20 minutes to sediment the fine particles, and the supernatant was removed. The obtained solid was washed with pure water to obtain spherical microparticles of poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylammonium chloride). The average particle size of the obtained microparticles was 90 nm, and the CV was 8.6%. The glass transition temperature is approximately 59°C. [Production of insulating fine particle-coated conductive particles] Nickel-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having a nickel film with a thickness of 0.125 μm and an average particle diameter of 3 μm on the surface of spherical resin particles were prepared. The resin particles are composed of cross-linked acrylic resin and have a glass transition temperature of 120°C. Add 5.0 g of the above-mentioned nickel-plated particles to 25 mL of toluene, and stir to obtain a dispersion of nickel-plated particles. Titanium-based coupling agent (Plenact KR-TTS manufactured by Ajinomoto Fine-Techno Co., Ltd., in the above general formula (I'), p is 3, r is 1, R ¹¹ is isopropyl, R ¹² is -OCO-, q= 1, R ¹³ is heptadecanyl compound) 0.1g, add this dispersion, stir at room temperature for 20 minutes to perform surface treatment. Thereafter, the particles were filtered through a membrane filter with a mesh size of 2.0 μm, and the nickel-plated particles having a titanium-based coupling agent layer on the surface were collected. Add 100 mL of a mixture of mass standard ethanol: pure water = 75:25 to the collected nickel-plated particles, perform surface treatment, and obtain a dispersion of nickel-plated particles. The insulating fine particles and Na ₂ SO ₄ obtained above were added to this dispersion, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the Na ₂ SO ₄ concentration was 5 mmol/L. After removing the supernatant, washing was repeated three times with pure water, and then vacuum dried at 50° C. to obtain insulating microparticle-coated conductive particles. The coverage ratio of the insulating fine particles in the obtained coated particles was determined by the following method. The results are shown in Table 1.

(Comparative Example 1) [Production of phosphonium-based insulating fine particles] Insulating fine particles were obtained in the same manner as in Example 1. [Production of insulating fine particle-coated conductive particles] In Example 1, surface treatment with a titanium-based coupling agent was not performed. Specifically, nickel-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having a nickel film with a thickness of 0.125 μm and an average particle diameter of 3 μm were prepared on the surface of the spherical resin particles. The resin particles are composed of cross-linked acrylic resin and have a glass transition temperature of 120°C. Add 5.0 g of the above-mentioned nickel-plated particles to 100 mL of pure water, and stir to obtain a dispersion of nickel-plated particles. The phosphonium-based insulating fine particles obtained in Example 1 and Na ₂ SO ₄ were added to this dispersion, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the Na ₂ SO ₄ concentration was 5 mmol/L. After removing the supernatant, washing was repeated three times with pure water, and then vacuum dried at 50° C. to obtain insulating microparticle-coated conductive particles. Table 1 shows the coverage ratio of the insulating fine particles in the obtained conductive particles.

(Comparative Example 2) [Production of phosphonium-based insulating fine particles] Insulating fine particles were obtained in the same manner as in Example 1. [Production of insulating fine particle-coated conductive particles] In Example 2, surface treatment with a titanium-based coupling agent was not performed. In detail, a nickel film having an average height of 0.1 μm on the surface of the spherical resin particles, an average bottom length of 0.197 μm, an aspect ratio of 0.5, 1,030 protrusions, a thickness of 0.125 μm, and nickel plating with an average particle diameter of 3 μm were prepared. Particles (manufactured by Nippon Chemical Industries). The resin particles are composed of cross-linked acrylic resin and have a glass transition temperature of 120°C. Add 5.0 g of the above-mentioned nickel-plated particles to 100 mL of pure water, and stir to obtain a dispersion of nickel-plated particles. To this dispersion, the phosphonium-based insulating fine particles obtained in Example 1 and Na ₂ SO ₄ were added, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the Na ₂ SO ₄ concentration was 5 mmol/L. After removing the supernatant, washing was repeated three times with pure water, and then vacuum dried at 50° C. to obtain insulating microparticle-coated conductive particles. Table 1 shows the coverage ratio of the insulating fine particles in the obtained conductive particles.

(Comparative Example 3) [Production of ammonium-based insulating fine particles] Insulating fine particles were obtained in the same manner as in Example 7. [Production of insulating fine particle-coated conductive particles] In Example 7, surface treatment with a titanium-based coupling agent was not performed. Specifically, nickel-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having a nickel film with a thickness of 0.125 μm and an average particle diameter of 3 μm were prepared on the surface of the spherical resin particles. The resin particles are composed of cross-linked acrylic resin and have a glass transition temperature of 120°C. Add 5.0 g of the above-mentioned nickel-plated particles to 100 mL of pure water, and stir to obtain a dispersion of nickel-plated particles. The ammonium-based insulating fine particles obtained in Example 7 and Na ₂ SO ₄ were added to this dispersion, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the Na ₂ SO ₄ concentration was 5 mmol/L. After removing the supernatant, washing was repeated three times with pure water, and then vacuum dried at 50° C. to obtain insulating microparticle-coated conductive particles. The coverage ratio of the insulating fine particles in the obtained coated particles was determined by the following method. The results are shown in Table 1.

(Reference Example 1) Reference Example 1 is for comparison and evaluation of the electrical conductivity and insulation properties of coated particles having the same coverage ratio as Comparative Example 2. [Production of phosphonium-based insulating fine particles] Insulating fine particles were obtained in the same manner as in Example 1. [Production of insulating fine particle-coated conductive particles] A nickel film having an average height of 0.1 μm on the surface of the spherical resin particles, an average bottom length of 0.197 μm, an aspect ratio of 0.5, 1,030 protrusions, and a thickness of 0.125 μm was prepared. , Nickel plating particles with an average particle diameter of 3 μm (manufactured by Nippon Chemical Industry). The resin particles are composed of cross-linked acrylic resin and have a glass transition temperature of 120°C. Add 5.0 g of the above-mentioned nickel-plated particles to 25 mL of toluene, and stir to obtain a dispersion of nickel-plated particles. Titanium-based coupling agent (Plenact KR-TTS manufactured by Ajinomoto Fine-Techno Co., Ltd., in the above general formula (I'), p is 3, r is 1, R ¹¹ is isopropyl, R ¹² is -OCO-, q= 1, R ¹³ is heptadecanyl compound) 0.1g, add this dispersion, stir at room temperature for 20 minutes to perform surface treatment. Thereafter, the particles were filtered through a membrane filter with a mesh size of 2.0 μm, and the nickel-plated particles having a titanium-based coupling agent layer on the surface were collected. Add 100 mL of a mixture of mass standard ethanol: pure water = 75:25 to the collected nickel-plated particles, perform surface treatment, and obtain a dispersion of nickel-plated particles. The insulating fine particles and Na ₂ SO ₄ obtained above were added to this dispersion, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 4,000 ppm on a mass basis, and the Na ₂ SO ₄ concentration was 5 mmol/L. After removing the supernatant, washing was repeated three times with pure water, and then vacuum dried at 50° C. to obtain insulating microparticle-coated conductive particles. The coverage ratio of the insulating fine particles in the obtained coated particles was determined by the following method. The results are shown in Table 1.

(Evaluation of coverage ratio) The coverage ratio of the coated particles obtained in Examples 1 to 7, Comparative Examples 1 to 3, and Reference Example 1 was evaluated. The coverage rate is obtained by the following method. The following radii use the above average particle size. >Measurement method of coverage ratio> For Examples other than Example 5, Comparative Examples and Reference Example 1, the following calculation formula is used to calculate the individual insulating fine particles when the insulating fine particles on the surface of the nickel plated particles are arranged in the most densely packed manner. Count N. N=4π(R+r) ² /2√3r ² (R: radius of nickel-plated particles (nm), r: radius of insulating fine particles (nm)) Counting insulating fine particles attached to nickel-plated particles in SEM The number n, the coverage rate is calculated by the following formula. Coverage rate (%) = (n/N) × 100 The coverage rate used for evaluation is the average value of 20 nickel-plated particles. In Example 5, the reflected electron composition (COMPO) image of the SEM photographic image of the coated particles was input into an automatic image analysis device (LUZEX (registered trademark) AP manufactured by NIRECO), and the calculation was performed using the 20 coated particles in the COMPO image as the object. .

[Table 1] insulating particles Whether there are protrusions surface treatment agent Coverage rate (%) Example 1 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) without KR-TTS 68.3 Example 2 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) have KR-TTS 60.2 Example 3 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) without KR-41B 68.0 Example 4 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) have KR-41B 59.0 Example 5 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) without KR-TTS 80.2 Example 6 Poly(styrene/divinylbenzene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) without KR-TTS 70.9 Example 7 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylammonium chloride) without KR-TTS 23.0 Comparative example 1 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) without without 18.4 Comparative example 2 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) have without 15.4 Comparative example 3 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylammonium chloride) without without 3.8 Reference example 1 Poly(styrene/n-butyl acrylate/4-(vinylbenzyl)triethylphosphonium chloride) have KR-TTS 15.6

As shown in Table 1, after the conductive particles are treated as a titanium-based compound via a titanium-based coupling agent, the coated particles coated with the insulating fine particles show a better coverage rate compared with the coated particles not treated with the titanium-based coupling agent. Furthermore, the coated particles of the present invention show a good coverage rate even when conductive particles having many protrusions on the surface are used. Based on the above, in coated particles with an insulating layer covering conductive particles, a titanium compound is present on the surface of the conductive particles, and the insulating layer has a charged functional group. It can be seen that the adhesion between the conductive particles and the insulating layer is added. increase.

(Evaluation of electrical conductivity and insulation properties) Using the coated particles of Example 2, Comparative Example 2, and Reference Example 1, electrical conductivity and insulation properties were evaluated by the following method.

>Evaluation of electrical conductivity> An insulating adhesive containing 100 parts by mass of epoxy resin, 150 parts by mass of hardener and 70 parts by mass of toluene was mixed with 15 parts by mass of the coated particles obtained in Example 2, Comparative Example 2 and Reference Example 1 to obtain an insulating paste. . This paste was applied to the silicone-treated polyester film using a bar coater, and then the paste was dried to form a thin film on the film. The obtained thin film-forming film was placed between a glass substrate with aluminum vapor-deposited on the entire surface and a polyimide film substrate with a copper pattern formed at intervals of 50 μm, and electrical connection was performed. By measuring the conductive resistance between the substrates, the electrical conductivity of the coated particles was evaluated at room temperature (25°C, 50%RH). It can be estimated that the lower the resistance value, the higher the electrical conductivity of the coated particles. When evaluating the electrical conductivity of coated particles, those with a resistance value of less than 2Ω were scored as "very good" (indicated by "○" in Table 2), and those with a resistance value of 2Ω or more and less than 5Ω were rated as "good" (indicated by "△" in Table 2 ” indicates), and those with a resistance value of 5Ω or more are recorded as “defective” (indicated by “╳” in Table 2). The results are shown in Table 2.

>Insulation Measurement> Micro-compression testing machine MCTM-500 (manufactured by Shimadzu Corporation) was used to compress the coated particles of Example 2, Comparative Example 2, and Reference Example 1 at a load speed of 0.5 mN/second using 20 coated particles as objects. The insulation properties of the coated particles are evaluated by measuring the compression deformation until the resistance value is detected. It can be estimated that the greater the compression deformation until the resistance value is detected, the higher the insulation properties of the coated particles are. To evaluate the insulation properties of coated particles, if the arithmetic mean of the compression deformation when the resistance value is detected is 10% or more, it is recorded as "very good" (indicated by "○" in Table 2). The arithmetic mean of the compression deformation is If the value is greater than 3% and less than 10%, it is recorded as "good" (indicated by "△" in Table 2). If the arithmetic mean compression deformation is less than 3%, it is recorded as "poor" (indicated by "╳" in Table 2). express). The results are shown in Table 2.

[Table 2] Electrification Insulation Example 2 ○ ○ Comparative example 2 ○ ╳ Reference example 1 ○ △

As shown in Table 2, compared with the coated particles of Comparative Example 2 that were not surface-treated, the coated particles of Example 2 that were surface-treated with a titanium-based coupling agent maintained electrical conductivity and were excellent in insulation properties. Reference Example 1, which has the same coverage rate as Comparative Example 2, has excellent insulation properties, and it can be seen that the insulation effect is obtained by the titanium-based coupling agent. [Industrial availability]

The coated particles of the present invention have excellent adhesion between the insulating layer and the conductive particles due to the phosphonium group contained in the insulating layer and the conductive titanium-based compound disposed on the surface of the conductive particles. The coated particles of the present invention have high connection reliability.

without.

Figure 1 is a scanning electron microscope image of the coated particles obtained in Example 1.

Claims (13)

A coated particle having: a metal film formed on the surface of a core material, conductive particles having a titanium compound having a hydrophobic group arranged on the outer surface of the metal film, and an insulating layer covering the conductive particles, the insulating layer having Compounds containing charged functional groups. The coated particle as claimed in claim 1, wherein the insulating layer is composed of a plurality of microparticles or is a continuous film. The coated particle according to claim 1, wherein the hydrophobic group is an aliphatic hydrocarbon group with a carbon number of 2 to 30. The coated particle as claimed in claim 1, wherein the charged functional group is a phosphonium group or an ammonium group. The coated particles according to claim 1, wherein the metal film is a metal film containing at least one selected from the group consisting of nickel, gold, silver, copper, palladium, nickel alloy, gold alloy, silver alloy, copper alloy, and palladium alloy. . The coated particle according to claim 1, wherein the insulating layer is composed of a polymer of at least one polymerizable monomer selected from the group consisting of styrenes, esters and nitriles. The coated particle as claimed in claim 1, wherein the surface of the conductive particle has a plurality of protrusions. A conductive material including the coated particles as described in any one of claims 1 to 7 and an insulating resin. A method for producing coated particles, including the first step of polymerizing a polymerizable composition including a polymerizable compound having a charged functional group to obtain insulating fine particles having a charged functional group on the surface, and The second step of providing a titanium-based compound with a hydrophobic group on the surface of the conductive particles (either the first step and the second step may be performed first or at the same time), and the dispersion liquid containing the insulating fine particles, and The third step is to mix conductive particles having a titanium-based compound having a hydrophobic group on the surface, and attach insulating fine particles having a charged functional group to the surface of the conductive particles. The manufacturing method of coated particles according to claim 9 further includes a fourth step of heating the coated particles obtained in the third step to bring the insulating particles into a molten state and coating the surface of the conductive particles in a film-like manner. The manufacturing method of coated particles according to claim 9 further includes: adding an organic solvent to the dispersion of the coated particles obtained in the third step, so that the insulating fine particles are in a dissolved state, and the surface of the conductive particles is coated in a film shape. Step 4. The method for producing coated particles according to any one of claims 9 to 11, wherein the hydrophobic group is an aliphatic hydrocarbon group with a carbon number of 2 to 30. The method for producing coated particles according to any one of claims 9 to 11, wherein the charged functional group is a phosphonium group or an ammonium group.