JP6825170B2 - Coating particles, conductive materials containing them, and methods for producing coating particles - Google Patents

Description

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

The conductive particles in which a metal film such as nickel or gold is formed on the surface of the resin particles are used as a conductive material such as a conductive adhesive, an anisotropic conductive film, and an anisotropic conductive adhesive.
In recent years, with the further miniaturization of electronic devices, the circuit width and pitch of electronic circuits have become smaller and smaller. Along with this, as the conductive particles used in the above-mentioned conductive adhesive, anisotropic conductive film, anisotropic conductive adhesive and the like, those having a small particle size are required. When conductive particles having such a small particle size are used, the amount of the conductive particles blended in the conductive material must be increased in order to improve the connectivity. However, when the blending amount of the conductive particles is increased, a short circuit occurs due to conduction in an unintended direction, that is, conduction in a direction different from that between the counter electrodes, and it is difficult to obtain insulation in that direction. ing.

In order to solve the above-mentioned problems, the surface of the conductive particles was coated with an insulating substance having a functional group having an affinity for the metal film to prevent the metal films of the conductive particles from coming into contact with each other. Insulating layer coated conductive particles are used. There is known a technique of surface-treating such conductive particles with an organic treatment agent before coating the metal surface with an insulating substance.

For example, Patent Document 1 describes that the metal surface of conductive particles is treated with a rust preventive agent, and insulating particles having a hydroxyl group are attached to the treated conductive particles.
Further, Patent Document 2 describes that the metal surface of the conductive particles is treated with a triazole compound, and the insulating particles having an ammonium group are attached to the treated conductive particles.

Japanese Unexamined Patent Publication No. 2014-29857 International Publication No. 2016/063941 Pamphlet

In the conductive particles coated with the insulating particles, it has been an issue to improve the adhesion between the insulating particles and the conductive particles. The adhesion between the insulating particles and the conductive particles is important for conducting conduction between the counter electrodes (hereinafter, also simply referred to as connection reliability) while obtaining insulation in a direction different from that of the counter electrodes. 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 consider the adhesion between the insulating particles and the conductive particles. It's not a thing. Therefore, an object of the present invention is to provide conductive particles coated with an insulating layer that can solve the problems of the prior art.

As a result of diligent research to solve the above-mentioned problems, the present inventors have obtained a titanium-based compound having a hydrophobic group on the surface of conductive particles when an insulating layer containing a charged functional group is used. The present invention was completed by finding that the insulating layer has an excellent affinity with the conductive particles having a titanium-based compound, and the coverage of the insulating substance on the conductive particles is further increased as compared with the prior art. did.

That is, in the present invention, the conductive particles having a metal film formed on the surface of the core material, the titanium-based compound having a hydrophobic group arranged on the outer surface of the metal film, and the conductive particles having the titanium-based compound. A coated particle having an insulating layer for coating the surface of the above, wherein the insulating layer has a compound containing a functional group having an electric charge.

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

Hereinafter, the present invention will be described based on a preferred embodiment.
The coated particles of the present embodiment are coated with conductive particles in which a metal film is formed on the surface of the core material and a titanium-based compound having a hydrophobic group is arranged on the outer surface of the metal film, and the conductive particles. A coating particle having an insulating layer and
The insulating layer has a compound containing a charged functional group. The outer surface of the metal film means the surface of the metal film opposite to the core material.

As the conductive particles, known particles conventionally used for the conductive adhesive, the anisotropic conductive film, and the anisotropic conductive adhesive can be used.
The core material of the conductive particles is in the form of particles, and can be used without particular limitation whether it is an inorganic substance or an organic substance. Examples of the inorganic core particles include metal particles such as gold, silver, copper, nickel, palladium, and solder, alloys, glass, ceramics, silica, metal or non-metal oxides (including hydrous substances), and aluminosilicates. Examples thereof include metal silicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal acid salts, metal halides and carbons. On the other hand, as the core material particles of the organic substance, for example, thermoplastics such as natural fiber, natural resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic acid ester, polyacrylic nitrile, polyacetal, ionomer, polyester and the like. Examples thereof include resins, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, diallyl phthalate resins and the like. These may be used alone or in combination of two or more. Among these, core material particles made of a resin material are preferable because they have a smaller specific gravity than metal core material particles, are less likely to settle, have excellent dispersion stability, and are easy to maintain electrical connection due to the elasticity of the resin. ..

When an organic substance is used as the core material particles, it is easy to maintain the shape of the core material particles in the anisotropic conductive connection step and that the glass transition temperature does not have a glass transition temperature or the glass transition temperature exceeds 100 ° C. It is preferable because the shape of the core material particles can be easily maintained in the step of forming the film. Further, when the core material particles have a glass transition temperature, the glass transition temperature is 200 ° C. or less, which means that the conductive particles tend to soften in the anisotropic conductive connection and the contact area becomes large, so that conduction can be easily obtained. Is preferable. From this viewpoint, when the core material particles have a glass transition temperature, the glass transition temperature is more preferably more than 100 ° C. and 180 ° C. or lower, and particularly preferably more than 100 ° C. and 160 ° C. or lower. The glass transition temperature can be measured by the method described in Examples described later.

When an organic substance is used as the core material particles, when the organic substance is a highly crosslinked resin, the glass transition temperature is hardly observed even if the measurement is attempted to 200 ° C. by the method described in the following Examples. In the present specification, such particles are also referred to as particles having no glass transition point. As a specific example of the core material having no glass transition temperature as described above, it is possible to obtain by copolymerizing the monomer constituting the organic substance exemplified above with a crosslinkable monomer in combination. it can. Examples of the crosslinkable monomer include tetramethylene di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide di (meth) acrylate, and tetraethylene oxide. (Meta) acrylate, 1,6-hexanedi (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimeterol propantri (meth) acrylate, tetramethylol methandi (meth) Meta) acrylate, tetramethylol methanetri (meth) acrylate, tetramethylol methanetetra (meth) acrylate, tetramethylol propanetetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol di (meth) acrylate, glycerol tridi (meth) Polyfunctional (meth) acrylates such as meta) acrylates, polyfunctional vinyl monomers such as divinylbenzene and divinyltoluene, vinyltrimethoxysilane, trimethoxysilylstyrene, γ- (meth) acryloxipropyltrimethoxysilane, etc. Examples thereof include silane-containing monomers, triallyl isocyanurate, diallyl phthalate, diallyl acrylamide, diallyl ether and the like. Especially in the field of COG (Chip on Glass), core material particles made of such a hard organic material are often used.

The shape of the core material particles is not particularly limited. Generally, the core material particles are spherical. However, the core material particles may have a shape other than a spherical shape, for example, a fibrous shape, a hollow shape, a plate shape, or a needle shape, and may have a large number of protrusions on the surface thereof or an irregular shape. In the present invention, spherical core material particles are preferable in terms of excellent filling property and easy coating of metal.
The shape of the conductive particles 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, and may have protrusions on its surface or may be amorphous. In the present invention, it is preferable that the shape is spherical or has protrusions on the surface in terms of excellent filling property and connectivity. When the conductive particles have a shape having protrusions on the surface, it is preferable to have a plurality of protrusions on the surface, and it is more preferable to have a plurality of protrusions on a spherical surface. When the conductive particles have a shape having a plurality of protrusions, the core material particles may have a plurality of protrusions, or the core material particles do not have the protrusions and the metal film has a plurality of protrusions. It may be. Preferably, the core material particles do not have protrusions and the metal film has a plurality of protrusions.

The coated particles of the present invention are excellent in adhesion to conductive particles of the insulating layer because a titanium-based compound is arranged on the surface of the metal film and the insulating layer has a compound containing a charged functional group. In order to ensure electrical conduction, protrusions may be provided on the surface of the conductive particles. By having the protrusions on the surface of the conductive particles, when the conductive particles are compressed by the electrodes at the time of mounting, the protrusions can effectively push away the insulating layer. As for the height H of the protrusions of the conductive particles, when the thickness of the insulating layer is L, H / L is 0.1 or more, which eliminates the insulating layer at the time of mounting to ensure electrical conduction. It is preferable from the viewpoint of making it simple. Further, it is preferable that the H / L is 10 or less from the viewpoint of obtaining the filling property and the insulating property in a direction different from that of the counter electrode. From these points, it is even more preferable that the H / L is 0.2 or more and 5 or less. In these preferable ranges, the thickness L refers to the average particle size of the insulating fine particles when the insulating layer is the insulating fine particles.

The height H of the protrusions is preferably 20 nm or more, particularly preferably 50 nm or more on average. The number of protrusions depends on the particle size of the conductive particles, but it is preferably 1 to 20000, particularly 5 to 5000, per particle from the viewpoint of further improving the conductivity of the conductive particles. .. The aspect ratio of the protrusions is preferably 0.3 or more, more preferably 0.5 or more. A large aspect ratio of the protrusions is advantageous because it can easily break through the oxide film formed on the electrode surface. The aspect ratio is a value defined by the ratio of the height H of the protrusion to the length D of the base of the protrusion, that is, H / D. The height H of the protrusion and the length D of the base of the protrusion are average values measured for 20 different particles observed by an electron microscope, and the aspect ratio of the protrusion is 20 different values observed by an electron microscope. The aspect ratio of the particles was calculated and the average value was calculated. The length D of the base refers to the length of the base of the protrusion along the surface of the conductive particles in the electron microscope.

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

For conductive particles having protrusions on the surface, if the insulating layer is insulating fine particles, the coating of the protrusions may be insufficient. In the coated particles of the present invention, since the titanium compound itself used in the present invention described later exhibits insulating properties, by arranging the titanium compound on the outer surface of the metal film, the conductive particles having protrusions on the surface can be obtained. Insulation can be further improved.

The metal film in the conductive particles has conductivity, and examples of the constituent metals include gold, platinum, silver, copper, iron, zinc, nickel, tin, lead, antimony, bismuth, cobalt, and indium. Examples thereof include metals such as titanium, antimony, bismuth, germanium, aluminum, chromium, palladium, tungsten and molybdenum, alloys thereof, and metal compounds such as ITO and solder. Among them, gold, silver, copper, nickel, palladium or solder is preferable because of its low resistance, and in particular, gold, silver, copper, nickel, palladium, gold alloy, silver alloy, copper alloy, nickel alloy or palladium alloy has insulating properties. It is preferably used because of its high bondability with a charged functional group in the fine particles, and preferably contains at least one 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.

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

Further, the metal film may not cover the entire surface of the core material particles, or may cover only a part thereof. When only a part of the surface of the core material particles is covered, the covering portions may be continuous, for example, island-like discontinuous coating may be performed. 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 height of the protrusions is not included in the thickness of the metal film referred to here.

As a method for forming a metal film on the surface of the core material particles, a dry method using a vapor deposition method, a sputtering method, a mechanochemical method, a hybridization method, etc., an electrolytic plating method, a wet method using an electroless plating method, etc. are used. Can be mentioned. Further, a metal film may be formed on the surface of the core material particles by combining these methods.

The conductive particles have a titanium-based compound on the outer surface of the metal film. When the conductive particles have a titanium-based compound on the surface, they easily adhere to the insulating layer having an electric charge, whereby the coverage of the insulating layer on the surface of the conductive particles can be sufficiently increased, and the insulating layer from the conductive particles can be sufficiently coated. Peeling is effectively prevented. Therefore, the short-circuit prevention effect of the insulating layer in a direction different from that between the counter electrodes is likely to be exhibited, and improvement in the insulating property in that direction can be expected.
Therefore, the coating particles of the present invention can improve the connection reliability.

As the titanium-based compound, a compound having a hydrophobic group is preferable from the viewpoint of affinity with the insulating layer. Examples of the hydrophobic group in the titanium-based compound include an organic group, and the number of carbon atoms thereof is preferably 2 or more and 30 or less from the viewpoint of its availability and affinity with the insulating layer. From the same viewpoint, the hydrophobic groups in titanium compounds include aliphatic hydrocarbon groups having 2 to 30 carbon atoms, aryl groups having 6 to 22 carbon atoms, and arylalkyl groups having 7 to 23 carbon atoms. Is preferably mentioned. The aryl group or arylalkyl group may be substituted with an aliphatic hydrocarbon group having 1 to 18 carbon atoms.
Examples of the aliphatic hydrocarbon group having 2 or more and 30 or less carbon atoms include a linear or branched saturated aliphatic hydrocarbon group and an unsaturated aliphatic hydrocarbon group, and examples of the saturated aliphatic hydrocarbon group. Examples include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl. Examples thereof include a group, an octadecyl group, a nonadecil group, an icosyl group, a henicosyl group, a docosyl group and the like. Examples of unsaturated aliphatic hydrocarbon groups include dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, nonadesenyl group, icosenyl group, eicosenyl group, henicosenyl group and docosenyl group as alkenyl groups. Be done.
Examples of the aryl group having 6 or more and 22 or less carbon atoms include a phenyl group, a tolyl group, a naphthyl group, an anthryl group and the like.
Examples of the arylalkyl group having 7 or more and 23 or less carbon atoms include a benzyl group, a phenethyl group, and a naphthylmethyl group.
As the hydrophobic group, a linear or branched aliphatic hydrocarbon group is particularly preferable, and a linear aliphatic hydrocarbon group is particularly preferable.
From the viewpoint of enhancing the affinity between the insulating layer and the conductive particles, the aliphatic hydrocarbon group as the hydrophobic group is more preferably 4 or more and 28 or less, and most preferably 6 or more and 24 or less. preferable.

As the titanium-based compound, for example, when the compound having the structure represented by the general formula (I) is present on the surface of the conductive particles, the affinity between the insulating layer and the conductive particles can be easily obtained and the solvent. It is particularly preferable because it is easy to disperse and the surface of the conductive particles can be treated uniformly.

(R ¹² is a divalent or trivalent group, R ¹³ is an aliphatic hydrocarbon group having 4 or more and 28 or less carbon atoms, an aryl group having 6 or more and 22 or less carbon atoms, or 7 or more and 23 or less carbon atoms. If it is an arylalkyl group, p and r are integers of 1 or more and 3 or less, satisfy p + r = 4, q is an integer of 1 or 2, and R ¹² is a divalent group, q is. When it is 1 and R ¹² is a trivalent group, q is 2. When q is 2, a plurality of R ^13s may be the same or different. * Represents a bond. )

Examples of the aliphatic hydrocarbon group having 4 or more and 28 or less carbon atoms represented by R ¹³ include those mentioned as an example of the above-mentioned aliphatic hydrocarbon group in the above-mentioned hydrophobic group.

Examples of the divalent group represented by R ¹² include -O-, -COO-, -OCO-, and -OSO _2- . Examples of the trivalent group represented by R ¹² include -P (OH) (O-) ₂ , -OPO (OH) -OPO (O-) _{2, and the} like.

In the general formula (I), * is a bond, and the bond may be bonded to the metal film of the conductive particles, or may be bonded to another atom, group, or the like. Other atoms, groups, etc. in that case may be described in the general formula (I') described later.

As the titanium-based compound having the structure represented by the general formula (I), the compound having the structure in which R ¹² is a divalent group in the general formula (I) has the availability and the conductive characteristics of the conductive particles. It is preferable in that it can be processed without damage. The structure 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-, and -OSO _2- , and p, r and R ¹³ are synonymous with the general formula (I).)

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

The titanium-based compound may or may not be chemically bonded to the metal on the surface of the conductive particles. For example, the titanium-based compound may be chemically bonded to the metal film by the bonding force in the general formulas (I) and (II) as described above. Examples of chemical bonds include covalent bonds and electrostatic bonds.

The titanium-based compound may be present on the surface of the conductive particles, and in that case, it may be present on the entire surface of the conductive particles, or may be present only on a part of the surface. The titanium-based compound may form a layer that covers a part or the whole of the surface of the conductive particles. By having the titanium-based compound on the surface of the conductive particles, the affinity with the insulating layer having a charged functional group on the surface becomes high.

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

The average particle size of the conductive particles is preferably 0.1 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less. When the average particle diameter of the conductive particles is within the above range, it is easy to secure conduction between the counter electrodes without causing a short circuit in the obtained coated particles in a direction different from that between the counter electrodes. In the present invention, the average particle size of the conductive particles is an average value of the particle size measured using a scanning electron microscope (SEM). When the conductive particles are spherical in the scanning electron microscope image, the particle diameter measured by using SEM is the diameter of the circular conductive particle image. When the insulating fine particles are not spherical, the particle diameter measured using SEM refers to the largest length (maximum length) of the line segments traversing the image of the conductive particles. However, when the conductive particles have protrusions, the above-mentioned maximum length of the portion other than the protrusions is defined as the average particle diameter. This also applies to the average particle size of the insulating fine particles described later.
Specifically, the average particle size of the conductive particles is measured by the method described in Examples.

The insulating layer in the present invention is composed of a polymer and has a compound containing a charged functional group. Examples of the insulating layer include those in which a plurality of insulating fine particles are arranged in a layer, or an insulating continuous film.

First, a case where the insulating layer is made of insulating fine particles and the fine particles contain a compound having a functional group having an electric charge will be described. In this case, the insulating fine particles are melted, deformed, peeled off, or moved on the surface of the conductive particles by thermocompression bonding the coated particles between the electrodes, so that the metal surface of the conductive particles in the thermocompression bonded portion is exposed. This enables continuity between the electrodes and provides connectivity. On the other hand, since the surface portion of the coated particles facing a direction other than the thermocompression bonding direction is generally maintained in a state of being coated on the surface of the conductive particles by the insulating fine particles, conduction in a direction other than the thermocompression bonding direction is prevented.
By containing a functional group having an electric charge on its surface (hereinafter, also simply referred to as “charged functional group”), the insulating fine particles easily adhere to the conductive particles having a titanium-based compound on the surface, whereby the conductive particles The ratio of the surface covered with the insulating fine particles can be made sufficient, and the peeling of the insulating fine particles from the conductive particles can be effectively prevented. Therefore, the short-circuit prevention effect of the insulating fine particles in a direction different from that between the counter electrodes is likely to be exhibited, and improvement in the insulating property in that direction can be expected.
Further, in the coated particles of the present invention, since the charged functional groups have the same charge, the insulating fine particles repel each other, so that a single layer of insulating fine particles is easily formed on the surface of the conductive particles. Therefore, when the coated particles of the present invention are used as an anisotropic conductive material or the like, poor conduction due to thermocompression bonding due to the presence of insulating fine particles in layers is effectively prevented, and improvement in connectivity is expected. it can.
Therefore, the connection reliability can be improved by the coating particles of the present invention in which the insulating layer is composed of insulating fine particles having a charged functional group on its surface.

Insulating fine particles preferably have a charged functional group on their surface. In the present specification, if it is confirmed that the insulating fine particles have a charged functional group and that the insulating fine particles are attached to the surface of the conductive particles by observation with a scanning electron microscope, "the functionality of the insulating fine particles having a charge". It corresponds to "having a group on the surface".

The shape of the insulating fine particles is not particularly limited and may be spherical or non-spherical. Examples of the shape other than the spherical shape include a fibrous shape, a hollow shape, a plate shape, and a needle shape. Further, the insulating fine particles may have a large number of protrusions on the surface thereof or may have an amorphous shape. Spherical insulating fine particles are preferable in terms of adhesion to conductive particles and ease of synthesis.

In the insulating fine particles, the charged functional group preferably forms a part of the chemical structure of the substance as a part of the substance constituting the insulating fine particles. In the insulating fine particles, the charged functional group is preferably contained in the structure of the polymer constituting the insulating fine particles. The charged functional group is preferably chemically bonded to the polymer constituting the insulating fine particles, and more preferably bonded to the side chain of the polymer. In the present specification, if it is confirmed that the insulating fine particles have a charged functional group and that the insulating fine particles are attached to the surface of the metal-coated particles by observation with a scanning electron microscope, "the insulating fine particles have a charged functional group". It corresponds to "having a group on the surface".

Preferred examples of the charged functional group include a phosphonium group, an ammonium group, a sulfonium group, an amino group and the like as a functional group having a positive charge. Further, as the functional group having a negative charge, a carboxyl group, a hydroxyl group, a thiol group, a sulfonic acid group, a phosphoric acid group and the like are preferably mentioned.

As the charged functional group, in particular, an onium-based functional group such as a phosphonium group, an ammonium group, or a sulfonium group makes it easier for the insulating layer to adhere to conductive particles having a titanium-based compound or an amide-based compound on the surface. The phosphonium group is most preferable.

As the onium-based functional group, those represented by the following general formula (1) are preferably mentioned.
(In the formula, X is a phosphorus atom, a nitrogen atom, or a sulfur atom, and R may be the same or different, and may be a hydrogen atom, a linear, branched or cyclic alkyl group, or an aryl group. N is 1 when X is a nitrogen atom and a phosphorus atom, and is 0 when X is a sulfur atom. * Is a bonder.)

For example, a halide ion is preferably used as a counter ion for a functional group having a positive charge. Examples of halide ^{ions, Cl -, F -, Br} -, I - , and the like.

Examples of the linear alkyl group represented by R include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group and an n-octyl group. n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, Examples thereof include an n-nonadecil group and an n-icosyl group.

The branched alkyl group represented by R includes an isopropyl group, an isobutyl group, an s-butyl group, a t-butyl group, an isopentyl group, an s-pentyl group, a t-pentyl group, an isohexyl group and an s-hexyl group. , T-hexyl group, ethylhexyl group and the like.

Examples of the cyclic alkyl group represented by R include cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group and cyclooctadecyl group.

Examples of the aryl group represented by R include a phenyl group, a benzyl group, a tolyl group, an o-xylyl group and the like.

R is a point that enhances the adhesion between the conductive particles and the insulating fine particles, and when the anisotropic conductive film is thermally pressure-bonded, the insulating fine particles are easily separated from the conductive particles to ensure continuity. From this point of view, it is preferably an alkyl group having 1 or more and 12 or less carbon atoms, more preferably an alkyl group having 1 or more and 10 or less carbon atoms, and an alkyl group having 1 or more and 8 or less carbon atoms. Is the most preferable. Further, it is also preferable that R is a linear alkyl group from the viewpoint that the insulating fine particles are close to the conductive particles and easily adhere to each other.

As a method of having a charged functional group on the surface of the insulating fine particles, when the insulating fine particles are composed of a polymer of a polymerizable composition composed of a polymerizable compound having an ethylenically unsaturated bond, the polymerizable composition Preferably contains a polymerizable compound having a charged functional group and an ethylenically unsaturated bond.

Examples of the polymerizable compound having an ethylenically unsaturated bond constituting the polymerizable composition include styrenes, olefins, esters, α and β unsaturated carboxylic acids, amides, and nitriles. Examples of styrenes include nuclear-substituted styrenes such as styrene, o, m, p-methylstyrene, dimethylstyrene, ethylstyrene and chlorostyrene, and styrene derivatives such as α-methylstyrene, α-chlorostyrene and β-chlorostyrene. Can be mentioned. Examples of olefins include ethylene and propylene. Examples of the esters include vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate, and methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, phenyl (meth) acrylate and the like. Examples include esters of (meth) acrylic acid. Examples of α and β unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid and the like. Salts of these α and β unsaturated carboxylic acids are also included in the α and β unsaturated carboxylic acids. Examples of amides include acrylamide and methacrylamide. Examples of nitriles include acrylonitrile. These may be further substituted, and examples of the substituent include a phosphonium group, an amino group, a quaternary ammonium group, an amide group, a sulfonium group, a sulfonic acid group, a thiol group, a carboxyl group, a phosphoric acid group and a cyano group. Examples thereof include an aldehyde group, an ester group and a carbonyl group. These monomers can be used alone or in combination of two or more. As the polymer constituting the insulating fine particles, in particular, a polymer of at least one polymerizable monomer selected from styrenes, esters and nitriles has a high polymerization rate and is easily spherical. It is preferable in that it can be done. When the polymer constituting the insulating fine particles has a plurality of types of structural units, the mode of existence of these structural units in the polymer may be random, alternate, or block. The polymer constituting the insulating fine particles may be crosslinked or non-crosslinked. When cross-linking the polymer constituting the insulating fine particles, as a cross-linking agent, for example, an aromatic divinyl compound such as divinylbenzene or divinylnaphthalene; allyl methacrylate, triacrylicformal, 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, trimethyl propantrimethacrylate, glycerin dimethacrylate, dimethylol-tricyclodecanediacrylate, penta Elythritol tri (meth) acrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, neopentyl glycol acrylic acid benzoic acid ester, trimethylpropanacrylic acid benzoic acid ester, 2-hydroxy-3-acryloyloxypropyl methacrylate, hydroxypivalin Examples thereof include di (meth) acrylate compounds such as an acid neopentyl glycol diacrylate, ditrimethylolpropane tetraacrylate, and 2-butyl-2-ethyl-1,3-propanediol diacrylate.

Examples of the polymerizable compound containing a charged functional group and having an ethylenically unsaturated bond include N, N-dimethylaminoethyl methacrylate, N, N as a polymerizable compound having an ethylenically unsaturated bond having an onium-based functional group. -Ammonium group-containing monomer such as dimethylaminopropylacrylamide, N, N, N-trimethyl-N-2-methacryloyloxyethylammonium chloride; monomer having a sulfonium group such as phenyldimethylsulfonium methacrylate; 4- (vinyl) Benzyl) triethylphosphonium chloride, 4- (vinylbenzyl) trimethylphosphonium chloride, 4- (vinylbenzyl) tributylphosphonium chloride, 4- (vinylbenzyl) trioctylphosphonium chloride, 4- (vinylbenzyl) triphenylphosphonium chloride, 2- (Metacloyloxyethyl) trimethylphosphonium chloride, 2- (methacloyloxyethyl) triethylphosphonium chloride, 2- (methacloyloxyethyl) tributylphosphonium chloride, 2- (methacloyloxyethyl) trioctylphosphonium chloride, 2-( Examples thereof include a monomer having a phosphonium group such as metachlorooxyethyl) triphenylphosphonium chloride.

When the insulating fine particles are a copolymer of a polymerizable compound having a charged functional group and having an ethylenically unsaturated bond and a polymerizable compound having no charged functional group and having an ethylenically unsaturated bond, the insulating fine particles are charged. The polymerizable compound having a functional group and the polymerizable compound having no charged functional group may be of the same type or different types. Examples of the types referred to here include the above-mentioned styrenes, olefins, esters, unsaturated carboxylic acids, amides, and nitriles. For example, at least one polymerizable compound having a charged functional group and having an ethylenically unsaturated bond and at least one polymerizable compound having no charged functional group and having an ethylenically unsaturated bond are of the same type, for example, styrene. It may be a kind.

In particular, it is preferable that the polymer constituting the insulating fine particles has a structural unit represented by the following general formula (2) or general formula (3) from the viewpoint of easy availability of the monomer and ease of polymer synthesis. Examples of R in the formulas (2) and (3) are as described above as examples of R in the general formula (1). The charged functional group may be bonded to any of the para-position, the ortho-position, and the meta-position with respect to the CH group of the benzene ring of the formula (2), and is preferably bonded to the para-position. In the formulas (2) and (3), a halide ion is preferably mentioned as the monovalent An ⁻ . Examples of halide ^{ions, Cl -, F -, Br} -, I - , and the like.

(In the formula, X, R, n are synonymous with the general formula (1). M is an integer of 0 to 5. An ⁻ indicates a monovalent anion.)

(In the formula, X, R, n are synonymous with the general formula (1). An ⁻ represents a monovalent anion. M ¹ is an integer of ¹ to 5. R ₅ is a hydrogen atom or a methyl group. Is.)

In the polymer constituting the insulating fine particles, the ratio of the structural unit to which the charged functional group is bonded is preferably 0.01 mol% or more and 5.0 mol% or less, and 0.02 mol% or more. More preferably, it is 2.0 mol% or less. Here, the number of structural units in the polymer counts the structure derived from one ethylenically unsaturated bond as one structural unit.

In the above general formula (2), m is preferably 0 to 2, more 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 kinds, more preferably three or more kinds of constitutional units, and it is preferable that at least one kind of these constitutional units has an ester bond in the structure. As a result, the glass transition temperature of the polymer can be easily lowered to a suitable level, the ratio 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 the insulating fine particles can be increased, and the insulating property between the coated particles can be made higher.

Examples of the structural unit having an ester bond in the structure include those derived from a polymerizable compound having both an ethylenically unsaturated bond and an ester bond in the structure. Examples of such polymerizable compounds include the esters listed above, specifically, vinyl esters such as vinyl propionate and vinyl benzoate, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. Examples thereof include esters of (meth) acrylic acid such as propyl, butyl (meth) acrylate, hexyl (meth) acrylate, and phenyl (meth) acrylate. In particular, as a polymerizable compound having both an ethylenically unsaturated bond and an ester bond in its structure, a compound having a group represented by -COOR ₁ or -OCOR ₂ (R ₁ and R ₂ are alkyl groups) in its structure. In particular, these groups are H ₂ C = CH * or H ₂ C = C (CH ₃ ) * (* is the bond of the bond in the group represented by -COOR ₁ or -OCOR ₂ above. The compound bound to) above is preferable. As R ₁ and R ₂ , a linear or branched alkyl group is preferable, the number of carbon atoms is preferably 1 or more and 12 or less, and more preferably 2 or more and 10 or less. These can be used alone or in combination of two or more.

In the polymer constituting the insulating fine particles, the ratio of the structural units having an ester bond in the structure to the total structural units is from the viewpoint of setting the glass transition temperature of the insulating fine particles in a suitable range and the insulation generated during the polymerization reaction. From the viewpoint that the sex fine particles can be taken out without being melted by heat and adhering to the wall surface of the reaction vessel, it is preferably 0.1 mol% or more and 30 mol% or less, and more preferably 1 mol% or more and 25 mol% or less. .. A preferable example of the structural unit having an ester bond in the structure referred to here is represented by, for example, the following general formula (4).

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

The glass transition temperature of the insulating fine particles is preferably lower than the glass transition temperature of the core material of the conductive particles. With such a configuration, the ratio of the area of the insulating fine particles in contact with the conductive particles and the adhesiveness between the insulating fine particles 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.
Further, the glass transition temperature of the insulating fine particles is preferably 40 ° C. or higher, preferably 45 ° C. or higher from the viewpoint of shape stability of the coated particles during storage and the ease of synthesizing the insulating fine particles. It is preferable, and it is particularly preferable that the temperature is 50 ° C. or higher. The glass transition temperature can be measured by the method described in Examples described later.

From the same point as 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, preferably 120 ° C. The temperature is more preferably 100 ° C. or lower, and particularly preferably 100 ° C. or lower. 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 higher, and more preferably 10 ° C. or higher.

Examples of the method for measuring the glass transition temperature include the following methods.
Using a differential scanning calorimeter "STAR SYSTEM" (manufactured by METTLER TOLEDO), 0.04 to 0.06 g of the sample was heated to 200 ° C. and cooled from that temperature to 25 ° C. at a temperature lowering rate of 5 ° C./min. .. Next, the temperature of the sample was raised at a heating rate of 5 ° C./min, and the amount of heat was measured. When a peak is observed, the temperature of the peak is used, and when a step is observed without a peak, a tangent line indicating the maximum slope of the curve of the step portion and an extension of the baseline on the high temperature side of the step are used. The temperature at the intersection of was taken as the glass transition temperature.

The average particle size (D) of the insulating fine particles is preferably 10 nm or more and 3,000 nm or less, and more preferably 15 nm or more and 2,000 nm or less. When the average particle size of the insulating fine particles is within the above range, it is easy to ensure continuity between the counter electrodes without causing a short circuit in the obtained coated particles in a direction different from that between the counter electrodes. In the present invention, the average particle size of the insulating fine particles is a value measured by observation using a scanning electron microscope, and specifically, it is measured by the method described in Examples described later.

The particle size distribution of the insulating fine particles measured by the above method varies. Generally, the width of the particle size distribution of the powder is represented by the coefficient of variation (hereinafter, also referred to as “CV”) represented by the following formula (1).
C. V. (%) = (Standard deviation / average particle size) x 100 ... (1)
This C.I. V. Larger indicates that the particle size distribution has a range, while C.I. V. A small value indicates that the particle size distribution is sharp. The coated particles of the present embodiment are C.I. V. It is preferable to use insulating fine particles of 0.1% or more and 20% or less, more preferably 0.5% or more and 15% or less, and most preferably 1% or more and 10% or less. C. V. However, there is an advantage that the thickness of the coating layer made of the insulating fine particles can be made uniform.

Further, the insulating layer may be a continuous film made of a polymer and having a charged functional group instead of the above-mentioned insulating fine particles. When the insulating layer is a continuous film containing a compound having a charged functional group, the metal surface of the conductive particles is exposed by thermocompression bonding the coating particles between the electrodes to melt, deform or peel the continuous film. This allows conduction between the electrodes and provides connectivity. In particular, the metal surface is often exposed by tearing the continuous film by thermocompression bonding the coated particles between the electrodes. On the other hand, in the surface portion of the coated particles facing a direction different from the thermocompression bonding direction, the coating state of the conductive particles by the continuous coating is generally maintained, so that conduction in a direction other than the thermocompression bonding direction is prevented. The insulating film also preferably has a charged functional group on its surface.

Even when the insulating layer is composed of a continuous film, the insulating continuous film easily adheres to the conductive particles having a titanium-based compound on the surface because it has a charged functional group. Further, as described later, when the continuous film is formed by heating the insulating fine particles or the insulating fine particles coated with the conductive particles are dissolved in an organic solvent, the insulating fine particles which are precursors of the insulating layer Can be uniformly arranged, so that there is an effect that the film thickness obtained by melting or dissolving the insulating fine particles can be made uniform. For these reasons, even when the insulating layer is composed of a continuous film, by having a titanium compound and a charged functional group, it is easy to exert a short-circuit prevention effect in a direction different from that between the counter electrodes, and the insulating property in that direction is improved. It will be improved and the connection reliability will be high. 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. Further, the surface of the continuous film may be flat, or may have irregularities on the surface resulting from melting or dissolving insulating fine particles.

The thickness of the continuous film is preferably 10 nm or more from the viewpoint of improving the insulating property in a direction different from that between the counter electrodes, and 3,000 nm or less is preferable from the viewpoint of ease of conduction between the counter electrodes. Is preferable. From this point of view, the thickness of the continuous film is preferably 10 nm or more and 3,000 nm or less, and more preferably 15 nm or more and 2,000 nm or less.

Like the insulating fine particles, the charged functional group in the continuous film preferably forms a part of the chemical structure of the substance as a part of the substance constituting the continuous film. In the continuous film, the charged functional group is preferably contained in at least one structure of the structural unit of the polymer constituting the continuous film. The charged functional group is preferably chemically bonded to the polymer constituting the continuous film, and more preferably bonded to the side chain of the polymer.
Examples of the charged functional group of the continuous film include the same as the charged functional group of the insulating fine particles.
Further, as an example of the structural unit of the polymer constituting the continuous film and its composition, the same as the above-mentioned structural unit of the polymer constituting the insulating fine particles and the composition thereof can be mentioned. The preferred range of ratios for the building blocks also applies to all continuous films. Examples of the glass transition temperature of the continuous film include those similar to the glass transition temperature of the insulating fine particles described above. Examples of the relationship between the glass transition temperature of the continuous film and the glass transition temperature of the core material particles include the same relationship as the relationship between the glass transition temperature of the insulating fine particles and the glass transition temperature of the core material particles described above.

When the insulating layer is a continuous film, it is preferable that the conductive particles are coated with insulating fine particles having a charged functional group on the surface thereof, and then the insulating fine particles are heated to obtain a continuous film. In this case, as described above, the insulating fine particles easily adhere to the conductive particles with respect to the conductive particles, whereby the ratio of the insulating fine particles covered with the insulating fine particles on the surface of the conductive particles becomes sufficient and the conductive particles are conductive. It is easy to prevent the insulating fine particles from peeling off from the particles. Further, as described above, the insulating fine particles having a charged functional group easily cover the conductive particles with a single layer. For these reasons, the continuous film obtained by heating the insulating fine particles that coat the conductive particles can have a uniform thickness and a high coating ratio on the surface of the conductive particles.

Originally, it is desirable that all the structures and properties of the continuous coating obtained by heat-treating specific insulating fine particles are measured by some means and then directly specified in the present specification. ..
However, at least at the time of filing, the structure or properties of other continuous coatings related to the effects of the present invention could not be confirmed at the technical level of the applicant.
Even if all the factors are identified, it is necessary to establish a new measurement method to identify the structure and characteristics of the continuous coating related to those factors, which requires extremely excessive economic expenditure and time. It takes.
From the above circumstances, in view of the fact that the nature of the patent application requires quickness, etc., the applicant shall be manufactured by the above-mentioned manufacturing method as one of the preferable features of the continuous coating. Was described.

Next, a suitable method for producing the coated particles of the present embodiment will be described.
The first step of the present production method is to polymerize a polymerizable composition containing a polymerizable compound having a charged functional group to obtain insulating fine particles having a charged functional group on the surface.
The second step of having a titanium compound on the surface of the conductive particles,
It has a third step of mixing a dispersion liquid containing insulating fine particles and conductive particles having a titanium-based compound on the surface to attach the insulating fine particles to the surface of the conductive particles.
Either of the first step and the second step may be performed first, or may be performed at the same time.

(First step)
The above-mentioned polymerizable composition is composed of two or more kinds of polymerizable compounds, and examples thereof include those in which at least one kind contains a charged functional group. Examples of the polymerizable compound include a polymerizable compound having an ethylenically unsaturated bond, which is a constituent unit of the polymer constituting the above-mentioned insulating fine particles. In addition, examples of the preferable polymerizable compound and its composition ratio include those that give a preferable composition unit of the polymer constituting the insulating fine particles and a preferable amount ratio thereof.

Examples of the polymerization method include emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, suspension polymerization and the like, and any of them may be used. However, in the case of soap-free emulsion polymerization, monodisperse fine particles are used and a surfactant is used. It is preferable because it has the advantage that it can be manufactured without using it. In the case of soap-free emulsion polymerization, a water-soluble initiator is used as the polymerization initiator. The polymerization is preferably carried out in an inert atmosphere such as nitrogen or argon.
As described above, insulating fine particles having a charged functional group on the surface can be obtained.

(Second step)
Conductive particles having a titanium-based compound on the surface can be obtained by mixing with the titanium-based compound in a solvent and then filtering. Examples of the titanium-based compound used for the surface treatment include those having the above-mentioned hydrophobic group, and preferably those having the above-mentioned structure represented by the general formula (I). As the compound having the structure represented by the general formula (I), the compound represented by the general formula (I') is preferably mentioned. Before the treatment with the titanium-based compound, the conductive particles may be treated with another organic agent or may not be treated.

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

In the general formula (I'), examples of the hydrocarbon group represented by R ¹¹ include an alkyl group having 1 to 12 carbon atoms. When p is 2 or more, the linking group in which the two R ^11s are bonded to each other includes a group represented by − (CH ₂ ) _W − (w is an integer of 2 or more and 12 or less). The methylene group in the group represented by R ¹¹ may be replaced once or twice or more by -O-, -COO-, and -OCO- under the condition that the oxygen atoms are not continuous. Examples of the alkyl group represented by R ¹¹ having 1 or more and 12 or less carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group. Can be mentioned.

Examples of the solvent for mixing the conductive particles and the titanium-based compound include water and an organic solvent. Examples of the organic solvent include toluene, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran, acetonitrile, N-methylpyrrolidone, dimethylformamide and the like. In the dispersion liquid in which the conductive particles and the titanium-based compound are added to the solvent, the concentration of the titanium-based compound is 0.1% by mass or more and 20% by mass or less. The concentration of the conductive particles in this dispersion is 1% by mass or more and 50% by mass or less. By filtering the dispersion liquid after the treatment, conductive particles having a titanium-based compound on the surface can be obtained.

When the surface is treated 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 higher and 50 ° C. or lower.

(Third step)
Next, the dispersion liquid containing the insulating fine particles and the conductive particles having a titanium-based compound on the surface are mixed to attach the insulating fine particles to the surface of the conductive particles.
Examples of the liquid medium of the dispersion liquid include water, an organic solvent, and a mixture thereof, and water, ethanol, or a mixed liquid of ethanol and water is preferable.

It is preferable that the dispersion liquid contains an inorganic salt, an organic salt or an organic acid from the viewpoint that it is easy to obtain coated particles having a coverage rate of a certain level or higher. Inorganic salts, the organic salts or organic acid, is preferably used which dissociate anion, as the ^{anion, Cl -, F -, Br} -, I -, SO 4 2-, CO 3 2- _{^{, NO 3 -, COO -,}} RCOO - (R is an organic group) is preferred, and the like. As the inorganic salt, for example _{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 , 0054 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. can be used. As the organic salt, Na oxalate, Na acetate, Na citrate, Na tartrate and the like can be used. As the organic acid, amino acids such as glycine, succinic acid, oxalic acid, acetic acid, citric acid, tartaric acid, malonic acid, fumaric acid, maleic acid and the like can be used.

The preferable concentrations of the inorganic salt, the organic salt and the organic acid vary depending on how much the insulating fine particles occupy the covering area in the surface area of the conductive particles, and are described in, for example, in the dispersion liquid after mixing the conductive particles. A concentration of 1 mmol / L or more and 100 mmol / L or less is preferable because it has a suitable coating ratio and it is easy to obtain coated particles having a single layer of insulating fine particles. From this viewpoint, the concentration of the inorganic salt, the organic salt and the organic acid in the dispersion is particularly preferably 1.0 mmol / L or more and 80 mmol / L or less.

When mixing the insulating fine particles and the conductive particles in the liquid medium, the dispersion liquid containing the insulating fine particles and the conductive particles may be mixed, or the dispersion liquid containing the conductive particles and the insulating fine particles are mixed. Alternatively, the insulating fine particles and the conductive particles may be charged into the liquid medium, respectively, or the dispersion medium containing the insulating fine particles and the dispersion medium containing the conductive particles may be mixed. The dispersion liquid containing the conductive particles and the insulating fine particles preferably contains 100 ppm or more and 100,000 ppm or less of the conductive particles on a mass basis, and more preferably 500 ppm or more and 80,000 ppm or less. ..
In the dispersion liquid containing the conductive particles and the insulating fine particles, the insulating fine particles are preferably contained at 10 ppm or more and 50,000 ppm or less, more preferably 250 ppm or more and 30,000 ppm or less on a mass basis. ..

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, from the viewpoint that coated particles having constant quality can be easily obtained, and particularly preferably 40 ° C. or higher. In particular, when the glass transition temperature of the insulating fine particles is Tg ° C., the temperature of the dispersion is preferably Tg-30 ° C. or higher and Tg + 30 ° C. or lower. Within this range, the insulating fine particles adhere to the conductive particles while maintaining their shape, and it is easy to obtain a suitable contact area between the insulating fine particles and the conductive particles, which is preferable. However, since the insulating fine particles having the charged functional group of the present invention have a high affinity with the conductive particles, they can be sufficiently coated within the above temperature range.

In the dispersion liquid after mixing the conductive particles, the time for adhering the insulating fine particles to the conductive particles is preferably 0.1 hour or more and 24 hours or less. During this time, it is preferable to stir the dispersion. Then, the solid content of the dispersion liquid is washed and dried as necessary to obtain coated particles in which insulating fine particles having a charged functional group are attached to the surface of the conductive particles.

As described above, by heating the coated particles in which the insulating fine particles are attached to the surface of the conductive particles, the surface of the conductive particles can be coated in a film shape with the insulating fine particles in a molten state. By forming the insulating fine particles into a film, the insulating property becomes stronger. Examples of the heating method include a method of heating the dispersion liquid after adhering insulating fine particles to the surface of conductive particles, a method of heating the coated particles in a solvent such as water, and a method of heating the coated particles in an inert gas. Examples include a method of heating in the gas phase. The heating temperature is Tg + 1 ° C. or higher and Tg + 60 ° C. when the glass transition temperature of the polymer constituting the insulating fine particles is Tg because it is easy to form a uniform film without the insulating fine particles falling off. The following is preferable, Tg + 5 ° C. or higher and Tg + 50 ° C. or lower are more preferable, and Tg + 15 ° C. or higher is most preferable. The heating time is preferably 0.1 hour or more and 24 hours or less from the viewpoint that a uniform film shape can be easily formed. Further, when the coated particles are heated in the gas phase, the pressure condition can be under atmospheric pressure, reduced pressure or pressurized.

Further, the coated particles in which the insulating fine particles adhere to the surface of the conductive particles can be made into a fluid state by adding an organic solvent to the dispersion liquid, so that the surface of the conductive particles is in the form of a film. Can be coated on. When the insulating fine particles are dissolved, tetrahydrofuran, toluene, methyl ethyl ketone, N-methyl-2-pyrrolidone, N, N-dimethylformamide and the like can be used as the organic solvent. The amount of the organic solvent added should be 1 part by mass or more and 100 parts by mass or less with respect to 1 part by mass of the coating particles in the dispersion liquid because it is easy to form a uniform film without the insulating fine particles falling off. Is preferable, and more preferably 5 parts by mass or more and 50 parts by mass or less. The addition temperature is preferably 10 ° C. or higher and 100 ° C. or lower, and more preferably 20 ° C. or higher and 80 ° C. or lower, from the viewpoint that a uniform film shape is easily formed without the insulating fine particles falling off. The time for forming a film after the addition is preferably 0.1 hour or more and 24 hours or less from the viewpoint of forming a uniform film.

The coated particles having the surface of the conductive particles coated in a film shape may be subjected to an annealing treatment in order to further stabilize the continuous film. Examples of the annealing treatment method include a method of heating the coated particles in a gas phase such as an inert gas. The heating temperature is preferably Tg + 1 ° C. or higher and Tg + 60 ° C. or lower, and more preferably Tg + 5 ° C. or higher and Tg + 50 ° C. or lower, when the glass transition temperature of the polymer constituting the insulating fine particles is Tg. The heating atmosphere is not particularly limited, and the heating can be performed under any conditions of atmospheric pressure, reduced pressure, or pressurized in an inert gas atmosphere such as nitrogen or argon or an oxidizing atmosphere such as air.

Although the preferred production method has been described above, the coated particles of the present invention can also be produced by other production methods. For example, an insulating fine particle having no charged functional group is produced in advance by a polymerization reaction, and the obtained insulating fine particle is reacted with a compound having a charged functional group to introduce a charged functional group on the surface of the insulating fine particle. You may.

The coated particles obtained as described above have an insulating property and opposition between the coated particles due to the advantage of combining the conductive particles having a titanium-based compound on the surface and the insulating fine particles having a charged functional group or a continuous film. Utilizing the connectivity between electrodes, it is suitably used as a conductive material such as a conductive adhesive, an anisotropic conductive film, and an anisotropic conductive adhesive.

Hereinafter, the present invention will be described with reference to Examples. However, the scope of the present invention is not limited to these examples. The characteristics in the example were measured by the following method.

(1) Average particle size 200 particles are arbitrarily extracted from a scanning electron microscope (SEM) photograph (insulating fine particles have a magnification of 100,000 times and conductive particles have a magnification of 10,000 times). , The above particle size was measured for them, and the average value was taken as the average particle size.

(2) C.I. V. (Coefficient of variation)
From the measurement of the average particle size, it was calculated by the following formula.
C. V. (%) = (Standard deviation / average particle size) x 100

(3) Glass transition temperature With a differential scanning calorimetry device (METTTLER TOLEDO, STAR SYSTEM), the calorific value changes from a measured temperature of 25 ° C to 200 ° C under a nitrogen atmosphere at a lifting temperature of 5 ° C / min using the above procedure. It was measured.

(Example 1)
[Manufacturing of phosphonium-based insulating fine particles]
100 mL of pure water was put into a 200 mL four-necked flask equipped with a stirring blade having a length of 60 mm. After that, styrene monomer (manufactured by Kanto Chemical Co., Inc.) 30.00 mmol, n-butyl acrylate (manufactured by Kanto Chemical Co., Inc.) 5.3 mmol, 4- (vinylbenzyl) triethylphosphonium chloride (manufactured by Nippon Kagaku Kogyo) 0.30 mmol, and as a polymerization initiator. 2.50 mmol of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., V-50) was added. Nitrogen was aerated for 15 minutes to expel dissolved oxygen, then the temperature was raised to 60 ° C. and held for 6 hours to allow the polymerization reaction to proceed. The dispersion of fine particles after polymerization was sieved through a SUS sieve having an opening of 150 μm to remove agglomerates. The dispersion liquid from which the agglomerates had been removed was subjected to sedimentation of fine particles in a centrifuge (manufactured by Hitachi, Ltd., CR-21N) at 20,000 rpm for 20 minutes to remove the supernatant liquid. Pure water was added to the obtained solid and washed to obtain spherical fine particles of poly (styrene / n-butyl acrylate / 4- (vinylbenzyl) triethylphosphonium chloride). The average particle size of the obtained fine particles was 86 nm, and C.I. V. Was 7.4%. The glass transition temperature was about 62 ° C.
[Manufacturing of conductive particles coated with insulating fine particles]
Ni-plated particles (manufactured by Nippon Chemical Industrial Co., Ltd.) having a nickel film having 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 were made of crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. Toluene (25 mL) was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno, Plenact KR-TTS, in the above general formula (I'), p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is -OCO-, q = 1, R 0.1 g of (compound ¹³ having a heptadecyl group) was added to this dispersion and stirred at room temperature for 20 minutes for surface treatment. Then, it was filtered through a membrane filter having a mesh size of 2.0 μm, and Ni-plated particles having a layer of Ti-based coupling agent on the surface were recovered. A dispersion of Ni-plated particles was surface-treated by adding 100 mL of a mixed solution of ethanol: pure water = 75:25 to the recovered Ni-plated particles on a mass basis. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and the mixture was stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant, washing with pure water was repeated three times, and then vacuum dried at 50 ° C. to obtain insulating fine particle-coated conductive particles. The coverage of the obtained conductive particles with the insulating fine particles was determined by the following method. The results are shown in Table 1. An SEM photograph of the obtained coated particles is shown in FIG.

(Example 2)
[Manufacturing of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Manufacturing of conductive particles coated with insulating fine particles]
The surface of the spherical resin particles has 1,030 protrusions having an average height of 0.1 μm, an average base length of 0.197 μm, and an aspect ratio of 0.5, and has a thickness of 0. Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a nickel film of 125 μm and having an average particle diameter of 3 μm were prepared. The resin particles were made of crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. Toluene (25 mL) was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno, Plenact KR-TTS, in the above general formula (I'), p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is -OCO-, q = 1, R 0.1 g of (compound ¹³ having a heptadecyl group) was added to this dispersion and stirred at room temperature for 20 minutes for surface treatment. Then, it was filtered through a membrane filter having a mesh size of 2.0 μm, and Ni-plated particles having a layer of Ti-based coupling agent on the surface were recovered. A dispersion of Ni-plated particles was surface-treated by adding 100 mL of a mixed solution of ethanol: pure water = 75:25 to the recovered Ni-plated particles on a mass basis. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and the mixture was stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant, washing with pure water was repeated three times, and then vacuum dried at 50 ° C. to obtain insulating fine particle-coated conductive particles. The coverage of the obtained conductive particles with the insulating fine particles was determined by the following method. The results are shown in Table 1.

(Example 3)
[Manufacturing of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Manufacturing of conductive particles coated with insulating fine particles]
Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno, Plenact KR-41B, in the above general formula (I'), p is 3, r is 1, R ¹¹ is an isopropyl group, and R ¹² is -P (OH) (O-). _2. Insulating fine particle coating conductivity by the same method as in Example 1 except that 0.1 g of (a compound in which q = 1, R ¹³ is an octyl group) is added to a dispersion of Ni-plated particles to perform surface treatment. Obtained particles. The coverage 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)
[Manufacturing of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Manufacturing of conductive particles coated with insulating fine particles]
Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno, Plenact KR-41B, in the above general formula (I'), p is 3, r is 1, R ¹¹ is an isopropyl group, and R ¹² is -P (OH) (O-). _2. Insulating fine particle coating conductivity by the same method as in Example 2 except that 0.1 g of (a compound in which q = 1, R ¹³ is an octyl group) is added to a dispersion of Ni-plated particles to perform surface treatment. Obtained particles. The coverage 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 prepare a dispersion, and the dispersion was stirred at 95 ° C. for 6 hours. After the stirring is completed, the solid content is separated using a membrane filter having a mesh size of 2 μm, and dried to obtain coated particles coated with an insulating layer consisting of a continuous film having a maximum thickness of 50 nm and a minimum thickness of 20 nm. Obtained. The coverage of the obtained coated particles with an insulating layer composed of a continuous coating was determined by the following method. The results are shown in Table 1.

(Example 6)
[Manufacturing of phosphonium-based insulating fine particles]
100 mL of pure water was put into a 200 mL four-necked flask equipped with a stirring blade having a length of 60 mm. After that, divinylbenzene monomer (manufactured by Nippon Steel & Sumitomo Metal) 15.0 mmol as a crosslinkable monomer, styrene monomer (manufactured by Kanto Chemical Co., Ltd.) 30.00 mmol as a non-crosslinkable monomer, and n-butyl acrylate (manufactured by Kanto Chemical Co., Inc.) 5.3 mmol, 4- (Vinylbenzyl) Triethylphosphonium chloride (manufactured by Nippon Chemical Co., Ltd.) 0.03 mmol, and 2,2'-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., V-50) as a polymerization initiator 0. 50 mmol was charged. Nitrogen was aerated for 15 minutes to expel dissolved oxygen, then the temperature was raised to 60 ° C. and held for 6 hours to allow the polymerization reaction to proceed. The dispersion of fine particles after polymerization was sieved through a SUS sieve having an opening of 150 μm to remove agglomerates. The dispersion liquid from which the agglomerates had been removed was centrifuged with a centrifuge (manufactured by Hitachi, Ltd., CR-21N) at 20,000 rpm for 20 minutes to settle the fine particles, and the supernatant liquid was removed. Pure water was added to the obtained solid and washed to obtain spherical fine particles of poly (styrene / divinylbenzene / n-butyl acrylate / 4- (vinylbenzyl) triethylphosphonium chloride). The average particle size of the obtained fine particles was 220 nm, and C.I. V. Was 9.7%.
[Manufacturing of conductive particles coated with insulating fine particles]
Insulating fine particle-coated conductive particles were obtained in the same manner as in Example 1. The coverage 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)
[Manufacturing of ammonium-based insulating fine particles]
100 mL of pure water was put into a 200 mL four-necked flask equipped with a stirring blade having a length of 60 mm. After that, styrene monomer (manufactured by Kanto Chemical Co., Inc.) 30.00 mmol, n-butyl acrylate (manufactured by Kanto Chemical Co., Inc.) 5.3 mmol, 4- (vinylbenzyl) triethylammonium chloride (manufactured by Nippon Chemical Co., Ltd.) 0.30 mmol, and polymerization. As an initiator, 0.50 mmol of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., V-50) was added. Nitrogen was aerated for 15 minutes to expel dissolved oxygen, then the temperature was raised to 60 ° C. and held for 6 hours to allow the polymerization reaction to proceed. The dispersion of fine particles after polymerization was sieved through a SUS sieve having an opening of 150 μm to remove agglomerates. The dispersion liquid from which the agglomerates had been removed was centrifuged in a centrifuge (manufactured by Hitachi, Ltd., CR-21N) at 20,000 rpm for 20 minutes to settle the fine particles, and the supernatant liquid was removed. Pure water was added to the obtained solid and washed to obtain spherical fine particles of poly (styrene / n-butyl acrylate / 4- (vinylbenzyl) triethylammonium chloride). The average particle size of the obtained fine particles was 90 nm, and C.I. V. Was 8.6%. The glass transition temperature was about 59 ° C.
[Manufacturing of conductive particles coated with insulating fine particles]
Ni-plated particles (manufactured by Nippon Chemical Industrial Co., Ltd.) having a nickel film having 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 were made of crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. Toluene (25 mL) was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno, Plenact KR-TTS, in the above general formula (I'), p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is -OCO-, q = 1, R 0.1 g of (compound ¹³ having a heptadecyl group) was added to this dispersion and stirred at room temperature for 20 minutes for surface treatment. Then, it was filtered through a membrane filter having a mesh size of 2.0 μm, and Ni-plated particles having a layer of Ti-based coupling agent on the surface were recovered. A dispersion of Ni-plated particles was surface-treated by adding 100 mL of a mixed solution of ethanol: pure water = 75:25 to the recovered Ni-plated particles on a mass basis. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and the mixture was stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant, washing with pure water was repeated three times, and then vacuum dried at 50 ° C. to obtain insulating fine particle-coated conductive particles. The coverage 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)
[Manufacturing of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Manufacturing of conductive particles coated with insulating fine particles]
In Example 1, no surface treatment with a Ti-based coupling agent was performed. Specifically, Ni-plated particles (manufactured by Nippon Chemical Industrial Co., Ltd.) having a nickel film having a thickness of 0.125 μm on the surface of spherical resin particles and having an average particle diameter of 3 μm were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-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 addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant, washing with pure water was repeated three times, and then vacuum dried at 50 ° C. to obtain insulating fine particle-coated conductive particles. Table 1 shows the coverage of the insulating fine particles in the obtained conductive particles.

(Comparative Example 2)
[Manufacturing of phosphonium-based insulating fine particles]
The same insulating fine particles as in Example 1 were obtained.
[Manufacturing of conductive particles coated with insulating fine particles]
In Example 2, no surface treatment with a Ti-based coupling agent was performed. Specifically, the surface of the spherical resin particles has 1,030 protrusions having an average height of 0.1 μm, an average base length of 0.197 μm, and an aspect ratio of 0.5, and is thick. Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a nickel film having a thickness of 0.125 μm and having an average particle diameter of 3 μm were prepared. The resin particles were made of crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-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 addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant, washing with pure water was repeated three times, and then vacuum dried at 50 ° C. to obtain insulating fine particle-coated conductive particles. Table 1 shows the coverage of the insulating fine particles in the obtained conductive particles.

(Comparative Example 3)
[Manufacturing of ammonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 7.
[Manufacturing of conductive particles coated with insulating fine particles]
In Example 7, no surface treatment with a Ti-based coupling agent was performed. Specifically, Ni-plated particles (manufactured by Nippon Chemical Industrial Co., Ltd.) having a nickel film having a thickness of 0.125 μm on the surface of spherical resin particles and having an average particle diameter of 3 μm were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-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 addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant, washing with pure water was repeated three times, and then vacuum dried at 50 ° C. to obtain insulating fine particle-coated conductive particles. The coverage 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 comparing the evaluation of the conductivity and the insulating property of the coated particles with the same coverage as that of Comparative Example 2.
[Manufacturing of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Manufacturing of conductive particles coated with insulating fine particles]
The surface of the spherical resin particles has 1,030 protrusions having an average height of 0.1 μm, an average base length of 0.197 μm, and an aspect ratio of 0.5, and has a thickness of 0. Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a nickel film of 125 μm and having an average particle diameter of 3 μm were prepared. The resin particles were made of crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. Toluene (25 mL) was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno, Plenact KR-TTS, in the above general formula (I'), p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is -OCO-, q = 1, R 0.1 g of (compound ¹³ having a heptadecyl group) was added to this dispersion and stirred at room temperature for 20 minutes for surface treatment. Then, it was filtered through a membrane filter having a mesh size of 2.0 μm, and Ni-plated particles having a layer of Ti-based coupling agent on the surface were recovered. A dispersion of Ni-plated particles was surface-treated by adding 100 mL of a mixed solution of ethanol: pure water = 75:25 to the recovered Ni-plated particles on a mass basis. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and the mixture was stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 4,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant, washing with pure water was repeated three times, and then vacuum dried at 50 ° C. to obtain insulating fine particle-coated conductive particles. The coverage 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)
The coverage of the coated particles obtained in Examples 1 to 7, Comparative Examples 1 to 3 and Reference Example 1 was evaluated. The coverage was determined by the following method. Moreover, the above-mentioned average particle diameter was used for the following radius.
<Measurement method of coverage>
In Examples, Comparative Examples, and Reference Examples 1 other than Example 5, the number N of the insulating fine particles when the insulating fine particles were densely packed on the surface of the Ni-plated particles was calculated by the following formula. ..
N = 4π (R + r) ² / 2√3r ²
(R: radius of Ni-plated particles (nm), r: radius of insulating fine particles (nm))
The number n of the insulating fine particles adhering to the Ni-plated particles was counted by SEM, and the coverage was calculated from the following formula.
Coverage (%) = (n / N) x 100
The coverage used for the evaluation was an average value of 20 Ni-plated particles.
In Example 5, the reflected electron composition (COMPO) image of the SEM photographic image of the coated particles was taken into an automatic image analyzer (Nireco Corporation, Luzex® AP), and 20 coated particles in the COMPO image. Was calculated for the target.

As shown in Table 1, the coated particles coated with the insulating fine particles after treating the conductive particles with the Ti-based coupling agent as the titanium-based compound are the coated particles obtained without the treatment with the Ti-based coupling agent. It showed a good coverage in comparison.
Further, the coating particles of the present invention showed a good coverage even when conductive particles having a large number of protrusions on the surface were used.
As described above, in the coated particles in which the conductive particles are coated with the insulating layer, the conductive particles and the insulating layer are formed by having a titanium-based compound on the surface of the conductive particles and having a functional group having an electric charge in the insulating layer. It can be seen that the adhesion of the particles is synergistically improved.

(Evaluation of conductivity and insulation)
The conductivity and the insulating property were evaluated by the following methods using the coated particles of Example 2, Comparative Example 2 and Reference Example 1.

<Evaluation of continuity>
An insulating adhesive obtained by mixing 100 parts by mass of an epoxy resin, 150 parts by mass of a curing agent and 70 parts by mass of toluene is mixed with 15 parts by mass of the coated particles obtained in Example 2, Comparative Example 2 and Reference Example 1. , An insulating paste was obtained. This paste was applied onto a 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 arranged between a glass substrate on which aluminum was vapor-deposited on the entire surface and a polyimide film substrate on which copper patterns were formed at a pitch of 50 μm, and electrical connection was made. By measuring the conduction resistance between the substrates, the conductivity of the coated particles was evaluated at room temperature (25 ° C., 50% RH). It can be evaluated that the lower the resistance value, the higher the conductivity of the coated particles. The conductivity evaluation of the coated particles is "very good" when the resistance value is less than 2Ω (indicated by the symbol "○" in Table 2), and "good" when the resistance value is 2Ω or more and less than 5Ω. (Indicated by the symbol "Δ" in Table 2), and those having a resistance value of 5Ω or more were designated as "defective" (indicated by the symbol "x" in Table 2). The results are shown in Table 2.

<Evaluation of insulation>
Using the micro-compression tester MCTM-500 (manufactured by Shimadzu Corporation), 20 coated particles were coated with Example 2, Comparative Example 2 and Reference Example 1 under the condition of a load speed of 0.5 mN / sec. The insulating properties of the coated particles were evaluated by compressing the particles and measuring the compressive displacement until the resistance value was detected. It can be evaluated that the larger the compressive displacement until the resistance value is detected, the higher the insulating property of the coated particles. For the insulation evaluation of the coated particles, those having an arithmetic mean value of compressive displacement of 10% or more until the resistance value is detected are regarded as "very good" (indicated by the symbol "○" in Table 2). An arithmetic mean value of compression displacement of more than 3% and less than 10% is regarded as "good" (indicated by the symbol "△" in Table 2), and an arithmetic mean value of compression displacement of 3% or less is "good". "Defective" (indicated by the symbol "x" in Table 2). The results are shown in Table 2.

As shown in Table 2, the coated particles of Example 2 surface-treated with a Ti-based coupling agent are superior in insulating properties while maintaining conductivity as compared with the coated particles of Comparative Example 2 which are not surface-treated. You can see that. Further, Reference Example 1, which has the same coverage as Comparative Example 2, has the same coverage as Comparative Example 2 but is excellent in insulating properties, so that the insulation effect of the Ti-based coupling agent can be obtained. It turns out that it is done.

In the coating particles of the present invention, the insulating layer and the conductive particles have excellent adhesion due to the phosphonium group contained in the insulating layer and the titanium-based compound arranged on the surface of the conductive conductive particles. Such coated particles of the present invention can have high connection reliability.

Claims (13)

Conductive particles in which a metal film is formed on the surface of the core material and a titanium-based compound having a hydrophobic group is arranged on the outer surface of the metal film,
A coated particle having an insulating layer for coating the conductive particle.
Coated particles in which the insulating layer contains a compound containing a charged functional group. The coating particle according to claim 1, wherein the insulating layer is composed of a plurality of fine particles or is a continuous film. The coated particle according to claim 1 or 2, wherein the hydrophobic group is an aliphatic hydrocarbon group having 2 to 30 carbon atoms. The coated particle according to any one of claims 1 to 3, wherein the functional group having an electric charge is a phosphonium group or an ammonium group. Any of claims 1 to 4, wherein the metal film is a metal film containing at least one selected from nickel, gold, silver, copper, palladium, nickel alloys, gold alloys, silver alloys, copper alloys and palladium alloys. The coated particle according to item 1. The coating particle according to any one of claims 1 to 5, wherein the insulating layer is made of a polymer of at least one polymerizable monomer selected from styrenes, esters and nitriles. The coated particle according to any one of claims 1 to 6, wherein the conductive particle has a plurality of protrusions on the surface. A conductive material containing the coating particles according to any one of claims 1 to 7 and an insulating resin. The first step of polymerizing a polymerizable composition containing a polymerizable compound having a charged functional group to obtain insulating fine particles having a charged functional group on the surface, and a hydrophobic group on the surface of the conductive particles. The second step (the first step and the second step may be performed first or at the same time) for having the titanium-based compound to have, a dispersion liquid containing insulating fine particles, and hydrophobicity on the surface. A method for producing coated particles, which comprises a third step of mixing conductive particles having a titanium-based compound having a sex group and adhering insulating fine particles having a charged functional group to the surface of the conductive particles. The coated particles according to claim 9, further comprising a fourth step of heating the coated particles obtained in the third step to melt the insulating fine particles and coat the surface of the conductive particles in a film shape. Production method. Further, the coating particles obtained in the third step have a fourth step of coating the surface of the conductive particles in a film shape with the insulating fine particles in a dissolved state by adding an organic solvent to the dispersion liquid. The method for producing coated particles according to claim 9. The method for producing coated particles according to any one of claims 9 to 11, wherein the hydrophobic group is an aliphatic hydrocarbon group having 2 to 30 carbon atoms. The method for producing coated particles according to any one of claims 9 to 12, wherein the charged functional group is a phosphonium group or an ammonium group.